Nuclear Plant Taken Down In Anticipation of Snowstorm

mdsolar writes Pilgrim Power Plant in Plymouth was taken offline in anticipation of the weekend snowstorm. According to a statement from Entergy, the owner of Pilgrim, the plant was taken off line in preparation of "a potential loss of offsite power or the grid's inability to accept the power Pilgrim generates." This is the second time this season the plant has been shut down due to storm conditions. On January 27 the facility was taken offline after the two main power transmission lines were knocked out by blizzard conditions. Although the transmission lines were restored within a few days, the plant remained offline until February 7 at which time it was reconnected to the grid.

Comments

A precaution when done ahead of time.

[Anonymous Coward]

An emergency measure when done after the fact.

Re:A precaution when done ahead of time.

[Mr D from 63]

The plant will be shut down in anticipation that the transmission grid will suffer problems and not be able to take the power. It has nothing to do with the plant itself or inability to run through the storm. Plants all over the northeast have kept the lights on for millions throughout that rash of harsh winter weather we have been having. Pilgrim is a reliable station still going strong after many years.

Snow covered solar panels won't be very useful, that is for certain. Windmills are shut down in blizzard conditions. Thankfully other sources are available.

Re:A precaution when done ahead of time.

[peragrin]

Snow covered solar panels aren't an issue. Try solar panels covered by 12-18 inches of ice. I have seen many of those in Massachusetts.

Re:A precaution when done ahead of time.

[Rei]

"Potential loss of offsite power" was listed as one of the two reasons for taking it down; the inability of the grid to accept power is only one. I would presume based on this that offsite power is part of their scenario for dealing with emergencies wherein the plant can no longer supply power for cooling its reactor, and hence the risk of loss of offsite power means an unacceptable meltdown risk should a disaster occur at the plant in the coming days.

Re:A precaution when done ahead of time.

[Mr D from 63]

True.

Loss of offsite power is an analyzed condition and the plant's license requires it to shut down when offsite power is lost. The safety analysis shows that the plant is in a higher risk level as it becomes reliant on its emergency diesels should another severe accident occur at that time. (Even though in those situations, the plant is designed to still be able to cope with all design basis accidents)

There is no license requirement to shut down in anticipation of a loss of offsite power, and the plant is designed to handle it safely.

Plants keep running through major storms all the time. This is particular to the local grid.

Re:A precaution when done ahead of time.

[Mr D from 63]

I'd like to correct my statement above which says "There is no license requirement to shut down in anticipation of a loss of offsite power".

Actually, there is a generic requirement to monitor grid reliability, and an unreliable grid determination could force a licensee to shut down. That is typically based on actual performance, not on anticipation, but I wanted to be accurate.

Re:A precaution when done ahead of time.

[confused one]

That's basically the idea. Shut down now, and use grid power to bring it down in a controlled fashion... Or, shut down later, and rely on the diesel backup generators to bring it down in a controlled fashion. Either works. Either is safe. Using grid power is safer.

Re:A precaution when done ahead of time.

[TubeSteak]

Pilgrim is a reliable station still going strong after many years.

Lol @ reliable. Pilgrim has been on the NRC's worst-ten shit list for a few years now.

The same day the storm hit, the NRC sent Pilgrim a letter.
http://pbadupws.nrc.gov/docs/ML1502/ML15026A069.pdf

Overall, the NRC has determined that your act ions have not provided the assurance level to fully meet all of the inspection objectives and have correspondingly determined that Pilgrim will remain in the Degraded Cornerstone of the Action Matrix by the assignment of two parallel White PI inspection findings. [Green, White, Yellow, Red, in increasing order of severity] [...] . Additionally, for one of the
root cause evaluations, inspectors determined that Entergy failed to investigate a deficient condition in accordance with corrective action program (CAP) requirements to ensure they fully understood all of the causes of one of the [four unplanned] scram events [that happened in 2013].

Reliable != multiple unplanned SCRAMs per year.

Anyways, on January 27, while the reactor was SCRAMing, these three things happened:

The High Pressure Coolant Injection System had to be secured due to failure of the gland seal motor.
The station diesel air compressor failed to start.
One of the four safety relief valves could not be operated manually from the control room.

Those safety relief valves are the ones that get used to vent pressure after the coolant injection system fails.

Pilgrim has problems. On top of all those problems, locals are spitting mad because the disaster plans fail to include scenarios like "giant blizzard shuts down all the roads and nobody can evacuate."

Re:A precaution when done ahead of time.

[Anonymous Coward]

You're an idiot.

Fukushima (most likely, there is some debate) would have survived the earthquake. The problem was loss of off site power, which means loss of cooling for decay heat. The pumps were flooded, it's not clear what would have happened even if the diesel generators would have been operable, but the cascade of things was the loss of power. That caused the disaster.

Pilgrim is a GE BWR3 Mark 1, very similar to Fukushima Diichi. Fukushima proves conclusively that the Mark 1 containment is too small, and unsafe. THAT is why this thing is shutdown, because they now know with pretty good certainty what happens when loss of cooling (off site power) happens.

Re:A precaution when done ahead of time.

[angel'o'sphere]

The problem is not 'bringing it down'.
The plant needs cooling after it shut down for MONTHS!

Re:A precaution when done ahead of time.

[Luckyo]

The primary cause was the failure of backup generators that got flooded by the tsunami. Earthquake was actually not a problem - it didn't damage anything crucial even though it was a hundred times more powerful than what plant was built to withstand. Secondary cause was loss of all regional infrastructure, including loss off off-site power, loss of ability to easily access to plant to get replacement power from mobile generators and other similar problems related to logistical difficulty of trying to get cooling when entire region is devastated with over 30.000 dead and hundreds of thousands displaced due to the massive flood. They had the plans, but having no easy access to anything in the region due to the massive flood made those plans impossible to implement.

Re:A precaution when done ahead of time.

[Luckyo]

Those are pretty severe problems, likely related to the age of the plant and the lack of necessary maintenance. Strange that regulator cannot force plant overhaul to newer safety hardware.

Re:A precaution when done ahead of time.

[Anonymous Coward]

What sealed Fukushima's fate was that it wasn't upgraded with hydrogen vents. If not for the explosion, those reactors would have been rendered inoperable but would not have damaged anything else.

Anyway, it's too bad, because Boston needs some way to get rid of snow, and nuclear power plants have a lot of heat.

Re:A precaution when done ahead of time.

[slashdot_commentator]

People have no clue how nuclear power plants work. The power that gets generated has to go somewhere, which is the power grid. If the nuclear power plant's connection to the grid gets severed (by bad weather, in this case), the power still has to go somewhere, or else it melts down the connecting infrastructure, and eventually triggers a nuclear meltdown situation. This is readily avoided by shutting down the reactor (before the problem starts) but since it can take a day before the reactor can be put back to operation, its a pain in the ass that management likes to avoid. Its like trying to stop a train in motion; you can't stop it with 30 seconds of advance notice.

Re:A precaution when done ahead of time.

[Mr D from 63]

Reliable from a generation standpoint, which seems to be the focus of the article. Historically, it has a good capacity factor.

None of the failures you mention above are acceptable, and that is why increased oversight is warranted. Yes, from a safety standpoint Pilgrim has lagged.

Re:A precaution when done ahead of time.

[LordLimecat]

The plant will be back online well before that though. Theres no "problem" here.

Re:A precaution when done ahead of time.

[LordLimecat]

I would think if you had nowhere else to send it, you could dump it into ground. Surely theres sufficient capacity there.

Re:A precaution when done ahead of time.

[Anonymous Coward]

Tubesteak you are more likely to choke to death on a Banana than to even so much as being injured by nuclear power, there or anywhere else.

Re:A precaution when done ahead of time.

[fnj]

If you had any understanding of electrical engineering whatever - or even a layman's nodding acquaintance with electricity - you would know you can't just short circuit the output. Sheesh.

Re:A precaution when done ahead of time.

[AmiMoJo]

Actually the earthquake damaged part of the emergency cooling system and thus prevented effective cooling that would have averted a meltdown. This did not become apparent until months after the disaster when it was possible to examine the pipes and valves that make up the system. They were pumping water in with fire engines, but it was being syphoned off by a broken valve and never made it to the reactor. Even if the valve had been okay, pipes further down were leaking anyway.

Search YouTube for NHK documentaries on the subject. NHK is like the Japanese version of the BBC, pretty reliable and they have done a lot of work examining what went wrong at Fukushima. Their documentaries are available in English.

Re:A precaution when done ahead of time.

[Aereus]

Known inadequate seawall led to flooding of the generators, which in a highly faulty design, were placed in the basement rather than behind the plant uphill. Another plant had made the necessary seawall upgrades and successfully repelled the tsunami wave and had no issues. Amongst a litany of other oversights, these were the two crucial ones.

Re:A precaution when done ahead of time.

[Anonymous Coward]

That's incorrect. The plant is designed to withstand a loss of offsite power and to be able to perform all shutdown and accident response functions using only the onsite diesel generators. However, if the plant operators think a loss of offsite power (LOSP) is likely, it's only prudent to take the unit offline. I'm a nuclear engineer with 30 years experience at commercial nuclear power plants.

Re:A precaution when done ahead of time.

[bluefoxlucid]

Seawall was adequate to anything Japan had seen for 1000 years. Japan is a 6.0 earthquake region, and took a 9.7; everything was built to handle at least 8.0, which was considered ridiculous. Resulting tsunami from the localized 9+ earthquake was out of scope, and never supposed to happen, in the same way a 15.0 earthquake is never supposed to happen.

Re:A precaution when done ahead of time.

[Anonymous Coward]

you can run it through a resistor into the ground though. Dumping excess power isn't exactly rare.

Re:A precaution when done ahead of time.

[Andy Dodd]

Yeah but the first day or two is the most critical. Decay heat declines exponentially.

Get through the first day or two and you have MUCH more time to respond to any subsequent issues.

Re:A precaution when done ahead of time.

[Anonymous Coward]

No, the big problem with large plants like this is that they have lots of "momentum", and it takes a long time to ramp up or down. When one of the main transmission lines goes down, they have lots of power that they need to dump somewhere.

Of course they can do it, but it's not something they want to do if they can avoid it. To make an analogy, it's like a freight train. They have an emergency brake, but it's not pleasant to use, so it's better to stop the train in anticipation of a problem on the track ahead.

dom

Re:A precaution when done ahead of time.

[leonardluen]

Windmills are shut down in blizzard conditions.

it seems rather ironic that windmills don't work when it is windy.

Re:A precaution when done ahead of time.

[Mr D from 63]

It is ironic. It is an engineering challenge to balance blade weight and strength. Sometimes even stopping them doesn't protect them enough;

http://www.utsandiego.com/news...

Re:A precaution when done ahead of time.

[Anonymous Coward]

" This is particular to the local grid." False. This is particular to this moment in time, this location and impending storm analysis.

Re:A precaution when done ahead of time.

[ChumpusRex2003]

That's not quite correct. There was no some damage to the emergency cooling systems, but it wasn't catastrophic.

At unit 1, the emergency isolation (condenser) cooling system (UPS powered) were manually turned off about 20-30 minutes after the earthquake, because they didn't want to "cold shock" the reactor, and switched instead to alternate methods of cooling (which required AC power). In the confusion that followed loss of AC power, they relied on staff to run outside and check the emergency cooling vents for steam. Staff were not familiar with the volume of steam which should flow from the isolation cooling system (should completely engulf the plant in thick cloud) and reported "faint steam" which was presumed to be due to operation of the isolation cooling system - but was, in fact, residual heat in the vent stacks, as they cooled following shutdown of the isolation condensers. Unit 1 likely suffered total core meltdown within 3-4 hours of the earthquake.

At plants 2 and 3, the emergency cooling system failed after the UPS systems powering the control systems depleted their batteries - a period of about 9 hours after the earthquake. Partial meltdown likely occurred within a few hours of core cooling loss. The extent of core damage is much lower than occurred in unit 1 because the first few hours are when decay heat is highest, and therefore severity of meltdown drops dramatically once through this period.

Fire pumps were brought in to inject water into the reactors at units 2 and 3. In this case, the water pooled in a tank and never reached the reactor. This was not due to a valve fault. The plan to inject water using fire pumps was an ad hoc plan, and the assumption was that the tank was connected to the injection line via a "positive displacement" pump (which would act as an obstruction to flow when unpowered), in fact, the pump was an impeller pump, through which the water could flow with ease. Even if this had worked, this was too late anyway, meltdown would have been near complete by the time the pumps were brought on site, and connections made.

The main lessons learned were: Don't turn off safety systems during an emergency Make sure staff are able to recognise the correct operation of safety systems Ensure that plans for the emergency provision of cooling water are pre-prepared, validated and well rehearsed. Ensure that emergency portable pumps are available near (but not too near) to site, and that their performance has been validated as acceptable Ensure adequate redundancy of hydrogen-oxygen catalytic recombiners Don't forget about the fuel pools.

Re:A precaution when done ahead of time.

[ChumpusRex2003]

The key point is to allow the reactor to cool for 24 hours or so in a maximally controlled environment - grid power, with backup diesel generators and full tanks for fuel. Once you're through the first 24 hours, the thermal load of decay heat is almost an order of magnitude lower, and much easier to handle.

It is also undesirable to expose the plant to grid transients. Short circuits on the grid, can cause severe mechanical disturbances to the alternator and turbomachinery. In a nuke plant, the LP turbines are typically very large, low speed machines with huge blades. These are susceptible to shock loadings due to their high moment of inertia. In fact, in nuke plant turbines, grid transients are one of the most important factors in determining fatigue life of the turbine assembly.

More over, there is a degree of thermo-hydraulic coupling between the turbine and reactor (or at least the steam generators) - these pressure and heat transients are also a contributor to fatigue life of the primary coolant circuit.

Re:A precaution when done ahead of time.

[Mr.CRC]

I don't buy this The generators have electrically excited field windings. Take down the exciter fields, and there is no electrical power output.

Generator fields can be taken down in milliseconds. A resistor to dump the inductive energy stored is of manageable size, vs. a resistor to load the entire generator output for a long period. Once you drop the exciter fields, you have a mechanically unloaded steam turbine, which still presents a risk of over speed.

SCRAM takes a few seconds, so the thermal output of the reaction can be halted in this time. But there is stored heat from the reaction left in the core. Plus, there is still power output, equivalent to the initial value of the decay heat release rate, typically about 7% of total thermal power output.

It may take a few minutes, or at best a few 10s of seconds to actuate a steam valve of the massive size which controls the turbine feed. Presumably there is an alternate path to divert this steam, such as to additional heat exchangers in the cooling towers, right?

What I anticipate would be done if the grid tie were severed, is that instead of completely cutting generation, within a few milliseconds the exciter field may be ramped down to reduce power output to 10-20% or so, while a resistor (of more manageable size vs. one able to take full power) is switched in. Mechanical braking can also be applied, to consume another 10-20% of the turbine power. Now you are not completely unloaded, but still under-loaded 60-80%.

The problem now consists of a transient turbine speed rise then decay to stop, based on the competing dynamics of combined partial braking and power dumping working against the time it takes to divert the steam. I would expect that this control problem has been designed and validation tested to death for any plant. But I am speculating a bit here (not about the generator field, but about how the power take down is accomplished. So, since you asserted that:

"power that gets generated has to go somewhere, which is the power grid. If the nuclear power plant's connection to the grid gets severed (by bad weather, in this case), the power still has to go somewhere, or else it melts down the connecting infrastructure, and eventually triggers a nuclear meltdown situation."

Then please explain why the situation as I anticipate it is incorrect, and things will go all to hell anyway?

Re:A precaution when done ahead of time.

[angel'o'sphere]

It is not days, it is weeks.

The Fukushima Reactors did not melt down a few days after the cooling was cut but roughly a week later.

They had also melted down if the cooling had failed 4 weeks later ...

Re:A precaution when done ahead of time.

[david_bonn]

A highly recommended, if a bit dated, book is _Normal Accidents_ by Charles Perrow. The sections on nuclear power plants are hair-raising reading.

The NRC used to have a rather frightening periodical called _Nuclear Safety_ which was also such hair-raising reading that it has been discontinued.

My observation is that accidents at nuclear plants seem to follow a power law, like earthquakes, where more severe incidents a less frequent. To me that means the people who argue that we really haven't had a "bad" accident yet or make special-case explanations for Chernobyl or Fukushima are missing the point -- we haven't had enough time yet to determine if far more catastrophic accidents are possible or not. A study of less major accidents, and accounts of the major ones, leads me to believe that we have just been very lucky so far. A great many of the accidents at nuclear power plants fall under what Feynman called "failure of design" where the system is not behaving in the way the engineers who designed the thing expected it to. That means we shouldn't have very much confidence at all in our ability to predict the probability of a catastrophic accident.

Some of the accidents and screwups at nuclear plants described in Perrow's book are just plain loony. One of the reactors at San Onofre was installed 180 degrees out of alignment and it took Southern California Edison seven months to notice. To correct this mistake they reversed the wiring in the control room. And such mistakes are by no means unique. At another plant overpressure in the reactor coolant led operators to somehow redirect hot, radioactive water into the drinking-water system at the plant -- what is a mystery to me is how can the two systems (reactor coolant and drinking water) possibly be connected? What is even more alarming is that there are such a bewildering array of ways for things to go wrong that there is very little commonality that lets us figure out how to do things better (not connecting drinking water to reactor coolant wouldn't be a bad start, and making sure the people building the plant read the plans wouldn't hurt either).

Re:A precaution when done ahead of time.

[Anonymous Coward]

Needless to say, none of the Fukushima, Chernobyl, or even 3-Mile Island accidents can even occur if you design your reactor correctly, so that it fails safely.

I simply do not understand our continued use of PWR's, they are inefficient, use a horribly toxic fuel cycle, and do not fail safe under certain conditions (ie they can meltdown in an uncontrolled way).

LFTR's are superior, in that they are more more thermally efficient (operating at higher temperatures, but at atmospheric pressure, or even below atmospheric pressure), use a much better fuel cycle (thorium is 10x more abundant than uranium, and these reactors can even reprocess existing radioactive waste as fuel), and cannot meltdown (even if you turn off all power to the reactor, the fuel will simply solidify in place, slowing the reaction down, and at worst, would melt through the freeze plug and drain into a subcritical passively cooled storage facility). The low pressure also reduces the possibility of leaks, since you do not need the high tolerances that high pressure requires.

We really need to start building 4th generation LFTR's if we want any chance of switching away from CO2 based energy for our electrical grid.

We could even use the energy from LFTR's to manufacture liquid fuel, so these could even help us get away from our current dependance on liquid fuel for transportation.

Re:A precaution when done ahead of time.

[LordLimecat]

If I had the understanding of an electrical engineer, I wouldnt have posed post as a query (albeit without a question mark).

WHY cant you just dump it into the ground?

Re:A precaution when done ahead of time.

[macpacheco]

Very interesting. I never read this before. Do you have a solid article explaining this ?
The type of argument the anti nuclear types will never accept. Need to get this world out, after I'm convinced it's solid.

Re:A precaution when done ahead of time.

[bluefoxlucid]

In lieu of looking for all that--which will be hard to find--I present you this for your amusement.

The April 11 aftershock was a magnitude 6.6. Aftershock. The original March earthquake was a 9.0 (not a 9.7; it was followed up by 6.0 and some 7.0+ aftershocks). According to Wikipedia, it was the most powerful earthquake ever recorded to have hit Japan, and the fourth most powerful earthquake in the world since modern record-keeping began in 1900.

There was an 8.9 in 869, 1150 years ago; an 8.6 in 1707; and an 8.4 in 1933. Some 8.3 quakes have hit Japan as recently as 2006. The Fukushima Daiichi plant managed to survive the 9.0 earthquake, mostly, enough for safety systems to stay online; unfortunately, the seawall was for a 5.5 meter high tsunami, and Japan took a 13-meter high tsunami instead. The 8.3 quakes in 2006 and thereabouts, as well as any storms coming from the Pacific Ocean to the Japanese coast, never managed to breach the seawall; the waves resulting from this event were substantially larger and more energetic.

The Fukushima region itself wasn't considered prone to massive quakes--the reactor wasn't designed for more than 0.45g, but took 0.55g forces when the 9.0 quake hit. They did ignore an internal risk assessment warning of tsunami waves up to 10 meters in height, claiming those numbers were ridiculous; nobody ever suggested ginormous earthquakes might happen right under the plant. Everything on the Events section of the Wikipedia page is fascinating, especially the diagram showing the inadequate seawall, 10 meter height the waves didn't fall short of, and 15 meter height the waves actually reached. Even a risk assessment considered unrealistic and alarmist fell 50% short of predicting the actual disaster.

Fukushima may be a good study of risk. In hindsight, we're guaranteed to find piles of flawed assessment methods and procedural issues that should have gotten attention; we'll likely realize these are routinely mishandled everywhere, or even indicative of a poor grasp of how certain environmental factors impact risk assessment industry-wide. As for gross mishandling and blame, Fukushima was hit with a massive disaster which even the most risk-averse estimates failed to predict or protect against: it was never going to survive that disaster, because we never through a disaster like that could happen. You may as well plan for a meteor strike or an alien invasion while you're at it.

Re:A precaution when done ahead of time.

[macpacheco]

Another good reason to go to a molten salt reactor (MSR).
Regular reactors are very lousy at load following (if they can do it at all).
MSRs are also much, much safer, so they could be deployed to handle a local city + export power to neighboring cities.
With its load following and much safer operation, just keep it online, only shutdown if 100% of its grid connections are finished.
Also it's higher temperature operation allow for making hydrogen, amonia and other chemicals from CO2, H2O and N2, instead of petroleum. Dessalinating sea water. General process heat for factories.
For dual (or triple) usage reactors, if they can't make a whole lot of electricity, turn up the chemical plant side.
Zero need for diesel generators, as decay heat dissipation is totally passive.
The fear of nuclear prevent reactors from being installed close to cities where they could provide massive district heating, like they do in the Baltic states.

Re:A precaution when done ahead of time.

[macpacheco]

The problem wasn't lack of heat decay weeks later. It was a cascade of problems that started with a full disruption in decay heat removal early on.
The tsunami hit 50 minutes after the shutdown.

Right after shutdown, decay heat produces 6.5% of pre shutdown power settings.
After one hour its down to 1.5%.
After a day its down to 0.4%.
After a week its down to 0.2%.
Assuming a large 4GWt reactor at full power prior to shutdown, 0.2% is less than 10MWt.
http://en.wikipedia.org/wiki/D...

After a week a reactor can probably survive another week without cooling power. It's not a usual condition, but it can be handled.
The most critical aspect is having electricity to operate the plants monitoring systems to know when to do small steam releases. Some radioactivity might be released, but it will be TMI levels of radioactivity (inconsequential). The critical aspect is avoiding the meltdown and avoiding hydrogen buildups. Water doesn't hold radioactivity, the concerns are releasing radioactivity sources (radio nuclides) which stay inside the reactor as long as it doesn't meltdown.

Days passed between loosing electricity for cooling and the hydrogen explosion. You should focus on when power was lost instead of when the explosion happened.
http://en.wikipedia.org/wiki/F...

Re:A precaution when done ahead of time.

[macpacheco]

Began operation december 9th 1972, or weeks from my birthday. I'm 42. Of course some of those ultra old reactors will have some issues.
I hope the NRC forces a shutdown of this one in the next license renewal.
But having those issues doesn't mean an accident waiting to happen.
Nuclear is robust. It's crazy robust.
Its easy to focus on Fukushima or Chernobyl.
And ignore the fact that if all of those 40+ year old reactors weren't built there would a whole lot more CO2 in the atmosphere, along with millions of tons of coal ash filled with Mercury, Cadmium, Arsenic, Uranium, Thorium in a format prime to fly with strong winds, be washed with strong rain.
By far the highest threat to nuclear reactors in the USA is earthquakes. Because they often come without any prior warning. A few hours at most.
Everything else is manageable, and new england has no earthquakes remotelly threatening to a nuke.
It's like trying to use Fukushima as a reason to get rid of Brazil's Angra I reactor. About as old a design as Pilgrim. But started operation in the early 80s. Its built in one of the safest possible nuclear sites in the world. It's 100km away from the nearest metro area (Rio de Janeiro). Brazil is actually building a Gen II nuclear reactor (Angra 3), materials were purchased 30+ years ago, and due to Brazilian incompetence it was left in storage, construction started 10 years ago. Am I concerned, hell no, cause it's built on the very same optimal site. No quakes, hurricanes, tornadoes, in a site impervious to floods, cooled with sea water.
Lets progressively replace those Gen II reactors, but then we have the problem that nuclear is crazy expensive to build today. It doesn't have to be expensive. But with the certainty of a costly and lenghty lawsuit from green peace and others (at least in the USA), with the people paranoid against any nuclear power, and politicians following the ignorant masses. And the NRC absolutelly unwilling to make it cost reasonable to do it the French way (absolute standardization leading to mass certification, only site specific issues must be reviewed on a site by site basis), but the NRC gets its money by the hour of regulatory services rendered, so they are vested in making regulatory services as lenghty (and expensive) as possible. Something like US$ 300 / hr this days.

Re:A precaution when done ahead of time.

[angel'o'sphere]

Sorry, bluntly: I don't grasp what you want to say.
Heat increases, it does not decrease, after a power failure accounting cooling.
The reason is decay of the waste products of the original reaction.
Hydrogene explosions have no influence on melt downs.
No idea what merits your analyzis had ... it is unclear to me what you want to express.

Re:A precaution when done ahead of time.

[macpacheco]

Your words:
> They had also melted down if the cooling had failed 4 weeks later ...

No. If the cooling was fine for 4 weeks and subsequently failed, cooling requirements would be small enough the reactor would survive without a meltdown or a hydrogen explosion. After 4 weeks decay heat is down to less than 0.1% of pre shutdown power. Or 15 times less heat than 1 hour after shutdown (around 1.5%), or 65 times less than immediately after the shutdown.

I'm pretty sure 0.1% power levels can be dealt with without damage to the reactor or radioactivity release, even without cooling for a whole other 4 weeks.

Re:A precaution when done ahead of time.

[angel'o'sphere]

No. If the cooling was fine for 4 weeks and subsequently failed, cooling requirements would be small enough the reactor would survive without a meltdown
No it would not. You can read that up in any book.

After 4 weeks decay heat is down to less than 0.1% of pre shutdown power.
The original waste products are still decaying, they decay for months until the thermal power is down.

I'm pretty sure 0.1% power levels 0.1% of what? We are talking about simple heat hot enough to melt the fuel elements, if it is not "removed". If there is no cooling the heat piles up. So if you only can "convect" away 0.05% of your 0.1% you have still to deal with the remaining 0.05% ... which will melt the reactor eventually.

The german wikipedia site is pretty clear about that, I don't find an english one quickly, however.

Re:A precaution when done ahead of time.

[macpacheco]

Except there are emergency systems to vent excess heat. Involving secondary containment. You know that huge space outside the real reactor but inside that huge concrete dome.
That's why I said "it can be dealt with", instead of the reactor would convect everything by itself.
Plus the reactor looses some heat to its surrounding environment. Convection is only the heat that reaches the heat exchangers. There's radiation from the reactor into the secondary containment too. As secondary containment is huge, there's quite a bit of air to heat up.
Plus convection capability is a function of temperature gradients, instead of power levels. The hotter the coolant is, the higher convection is. It's not by accident that AP1000 and ESBWR can do that without any pumps passively (even right after an emergency shutdown from full power). We're talking 65x less power, and dropping. Part of this process is continuously (but slowly) loosing coolant water into secondary containment (replenished from a large overhead tank).
The other aspect I couldn't find an answer to, is how long until a reactor shutdown from full power reaches a safe enough state for refuelling, or cold enough that fuel rods can be moved to cooling pools. But I doubt its even 2 months. Refuelling doesn't shutdown a reactor for months (and it's done ONLINE with CANDU reactors).
You are assuming 0.1% is a lot of power. It's not a little, but it's not a lot.
Finally what matters isn't coolant temps, but core fuel temps (meltdown happens at the interface between fuel and cladding, melting the Zr, hydrogen is primarily produced by Zr + H2O reactions). This means the coolant could reach a higher temperature under very low power with the cladding still within limits, further increasing heat losses.
I'm not a nuclear engineer, but those principles aren't nuclear specific, plus I have studied generalities about BWR and PWR in a formal class. It's basic thermodynamics.

Re:A precaution when done ahead of time.

[angel'o'sphere]

My point is: the literature claims it takes months to be on the safe side.

And I doubt that has anything to do with changing fuel rods. No one prevents you to simply pull out a rod and place a new one into a rector that has working cooling.

Re:A precaution when done ahead of time.

[macpacheco]

If this were possible with 4 week shutdown, the overheating problem would be fully prevented. If its fresh fuel, or a rod that has been cooled for a long enough time, it would have essentially zero decay heat. We move the decay heat problem from inside the reactor (which is designed to minimize heat loss except to the primary heat exchanger), to the spent fuel pool, which is designed to maximize heat dissipation.
Besides, on a shutdown reactor, you don't even need to replace fuel rods, those could be left empty, just remove all rods into the spent fuel pool, and decay heat power = zero.

Re:A precaution when done ahead of time.

[macpacheco]

Got confirmation from a nuclear professional. A refueling shutdown is around 4 weeks anyways. So in the discussed scenario, as long as the reactor didn't meltdown, just move the fuel to the spent fuel pool. This suggests it could be done even 2 weeks after an emergency shutdown, as decay heat is 0.2% @ 1wk and 0.1% @4wks, so in 2 wks it's around 0.15%.
Remember this has been stated again and again, the first week is critical. I would add that the 2nd week is still a little delicate, but from the 3rd week on, the reactor is safe (even without emergency cooling).

Re:A precaution when done ahead of time.

[angel'o'sphere]

Except for the 'if' correct.
If the hot rods where that easy to handle you could simply pull them out of the reactor and drop them into the water pools.
Obviously they are even after weeks to hot to handle them that simple, at least that is the most straight forward explanation.

Re:A precaution when done ahead of time.

[angel'o'sphere]

Note the last line of the article: http://www.scientificamerican....

Laymen article: http://www.quora.com/How-long-... ... spent fuel is in pools for about 10 years.

That is more interesting: http://www.nrc.gov/waste/spent...

This is a german article: http://de.m.wikipedia.org/wiki...Ãrme (contains umlaut a) ... http://en.wikipedia.org/wiki/D... the numbers vary a bit, the german one has a table in the middle, saying after a month the heat is 0.13% and after three months it is 0.07%

The next paragraph after that table states: fuel rods create enough decay heat to melt themselves _months_ after shutdown, if they are not cooled obviously.

Well, to get real numbers I guess we need a anti radiation suit, wait for the next melt down, and measure our selves ^_^ would you volunteer for the first two weeks?

Re:A precaution when done ahead of time.

[macpacheco]

If you remove a fuel rod one month after a shutdown, and leave it without water cooling, it will eventually melt. But I'm pretty sure it take in the order of a full day of more before it melts.

That's why there's this thing called a spent fuel pool. Water cools it. But that water needs NO forced circulation.

I don't know what kind of equipment is used to effect that in typical reactors. In a CANDU reactor (not a typical reactor), it's all robotics, as the process is done online, fuel rods are taken from the reactor even at full power. If decay heat was that critical that the rod would melt in minutes, this process wouldn't be possible.

I'm just explaining nuclear engineering facts that can't be questioned. If decay heat was anything like you try to pretend it is, those processes wouldn't be possible, yet they are done around the world many times per months.

Please go study nuclear facts. Nuclear engineering. Not anti nuclear propaganda you seems to like so much. bellona doesn't count. nuclear-news.net doesn't count. green peace doesn't count. Caldicott's blog doesn't count.

Re:A precaution when done ahead of time.

[macpacheco]

That's what I expected from you. Just FUD. You aren't interested in facts. Anti nuclear types can't accept simple logical facts. If you were right and I was wrong, refuelling within a month just wouldn't be possible. But IT is. The over 400 reactors in the world (except those that have online refuelling) must stop every 18 months or so, for a month to refuel. The one month shutdown is exactly due to decay heat. But the shutdown itsn't 2 months. It's not even 6 weeks. It's just one month.
Of course if fuel must be handled by people, they use radiation suits, dosimeters, thick gloves. And long tools.
If you stop to analyze this logically, you will start finding many of the crazy lies the anti type nukes created around Fukushima, to predict end of the world scenarios. Same thing for TMI. Guess what, 99% of predictions didn't happen. And the bulk of the remaining ones will fall down with another 10 years or so. It's all based on not knowing enough nuclear engineering or perverting nuclear engineering facts.

Re:A precaution when done ahead of time.

[macpacheco]

The sole reason you can't remove fuel rods from a recently shutdown PWR/BWR is this:
    The reactor must be depressurized before fuel can be removed.
    But after the reactor is down to 0.1% power, it can be depressurized, even without emergency cooling. There's a big water tank above the reactor that can be used to provide enough cooling after depressurization to allow for removing the fuel rods.
    Handling fuel rods shutdown 4 weeks prior is normal operations. They will be radioactive, but within limits for removal from the reactor to the spent fuel pool. Perhaps you don't know about radiation suits, and special tools nuclear operators use to deal with spent fuel.
    A spent fuel pool is big. Big enough to handle a couple times the full fuel load of a reactor. As long as one fuel pool has only old spent fuel or no fuel, freshly removed fuel will not boil off the pool. The spent fuel pool is normally a closed environment using fans to circulate the air, but in emergencies doors can be open which provide natural air circulation. Those are not my conclusions. Those are US NRC detailed scenarios, which have been confirmed by multiple nuclear regulatory agencies.

Re:A precaution when done ahead of time.

[angel'o'sphere]

I guess the links are selfexplanating.

Spent fuel rods are not the same as "unspent fuel rods" that remain after a shut down.

Spent fuel rods get removed from the reactor after they have sticked there for months. So your analysis that it is safe to remove them without them melting down in minutes is correct. And I never claimed anything otherwise.

We only talked about the fact that the whole reactor, can melt down without cooling even months after shut down. And I guess this topic is settled now after we both read the links I gave, or not?

Re:A precaution when done ahead of time.

[angel'o'sphere]

Sorry,
no idea where your hate is coming from.

Removing fuel rods has nothing to do with reactor melt downs and decay heat. No idea where you get that stupid idea from.

As you explained yourself a spent fuel rod still creates about 0.2% heat (in relation to a running rod) ... so what is your problem?

The one month shutdown is exactly due to decay heat. But the shutdown itsn't 2 months. It's not even 6 weeks. It's just one month.
What has that to do with the argument? Nothing.
The argument is: what happens if the cooling fails after that month. Can the reactor still melt down? Yes? No?

The facts I posted clearly state: YES.

Re:A precaution when done ahead of time.

[angel'o'sphere]

Again: removing rods never was an issue/topic of the discussion.

The question was: if the cooling fails after 4, 6, 8 weeks AFTER the reactor was shut down, can a melt down still happen?

Answer: YES:

If you still don't agree on that, you are beyond help.

Re:A precaution when done ahead of time.

[Luckyo]

To be fair, it almost did survive it. Other reactors at Fukushima in fact did survive it.

mdsolar strikes again

[peon_a-z,A-Z,0-9$_ !]

He probably wouldn't post something about a 'renewable' going offline, based on his posting history.

Re:mdsolar strikes again

[Anonymous Coward]

Hmm, yes, I was wondering how many windmills and solar panels can produce power when a very windy snowstorm blankets them with a thick layer of snow? You know, right when having a reliable supply of power is crucial for life-saving needs all around the country?

I would bet $100 it's pretty close to zero.

Re:mdsolar strikes again

[Gadget_Guy]

He probably wouldn't post something about a 'renewable' going offline, based on his posting history.

What difference does that make? You are attempting to discredit this story by maligning the submitter. That is known as playing the man, not the ball. Nothing that mdsolar wrote was untrue, and it didn't even sound judgemental.

Rest assured that if a renewable power station went offline there would be plenty of other people who would submit stories about it, and I'm sure lots of them would have similar partisan posting histories (albeit with an anti-renewable agenda). The question is, would you write a similar complaint about those submitters or is it just those who fail to talk in gushing tones about nuclear power that incur your wrath?

Re:mdsolar strikes again

[peon_a-z,A-Z,0-9$_ !]

While you're right, I am guilty of attacking the submitter, he has a history of posting "facts" with no further comment or context.

Is this story relevant? Maybe. Is this story abnormal? No. What is the first thing that will happen when an uninformed person reads this story? They'll probably post something like the AC with the headline "Devil's advocate" a few posts below after having formed an unjustified negative opinion.

There's a difference between posting pure "facts" and "just posting something with minimal information" with the intent to foster a negative viewpoint that supports his personally chosen cause. Borderline malicious.

Re:mdsolar strikes again

[Mr D from 63]

Well, read the article and realize it is the anticipated loss of the transmission system for which the plant is being shut down. That should have been the headline.

Re:mdsolar strikes again

[AK Marc]

So the windy snowstorm will cause the windmills to fail? How is that?

Re: mdsolar strikes again

[Anonymous Coward]

Yeah, fuck the planet. Why even bother.

Re:mdsolar strikes again

[Mr D from 63]

Windmills are shut down in very high winds to prevent damage.

Re:mdsolar strikes again

[Anonymous Coward]

>Rest assured that if a renewable power station went offline there would be plenty of other people who would submit stories about it

There would be? Topaz Solar Farm goes "offline" every single night, but there's no stories about that one, are there?

Re:mdsolar strikes again

[Mr D from 63]

Nothing that mdsolar wrote was untrue, and it didn't even sound judgemental.

To be fair, the title was changed by samzenpus. mdsolar's submittal title said something like "unreliable nuclear plant shut down....". An attempt to mislead on the reason for the shutdown.

Re:mdsolar strikes again

[ganjadude]

renewable power sources go offline all the time. Its called night time.

in all seriousness though you are spot on. this article didnt have any political tones on it, i didnt even think politically until the previous posters comment

Re: mdsolar strikes again

[Anonymous Coward]

On the bright side, many slashtards will freeze to death.

Re:mdsolar strikes again

[dbIII]

No. What is the first thing that will happen when an uninformed person reads this story?

They will take it on face value, most likely that it's both a good idea and standard operating procedure, unless of course they have an agenda to push.

Re:mdsolar strikes again

[AK Marc]

If the wind is that high, the snow won't collect on the solar panels that easily. It drifts off of high places, like roofs, and collects at fences and other things that catch the air. The stated combination won't happen as needed for the AC horror scenario to happen.

Re:mdsolar strikes again

[OhPlz]

Exactly. That's why during this time of wind gusts over 60mph, greater Boston has seen dozens of roof collapses.

Re:mdsolar strikes again

[Anonymous Coward]

Windmills, maybe. Wind turbines on the other hand have had variable pitch blades for decades and they are feathered in very high winds to prevent damage. i.e.: they're still turning to produce power.

Re:mdsolar strikes again

[Mr D from 63]

Maybe the snow won't collect on the panels, as another poster stated ice is a bigger issue where he/she lives. But it really doesn't matter under cloudy, blizzard conditions anyhow, not much sunlight is reaching those panels.

Re:mdsolar strikes again

[Tailhook]

You are attempting to discredit this story by maligning the submitter.

The story is FUD. That's mdsolar's MO; post transparently stupid, fear mongering stories about nuclear power. He deserves to be maligned; he's earned it.

Re:mdsolar strikes again

[Anonymous Coward]

1 foot of snow falls on top a solar panel.

Dead in the water.

Re:mdsolar strikes again

[AK Marc]

Flat roofs will collapse. They generally have walls around the edge, and will catch lots of snow. Almost all panels are elevated slightly, so they do a better job of letting the snow flow around them in a wind, especially when mounted on slanted roofs. Also, I haven't been following Boston weather, but there's a difference between a snow, followed by 60 mph winds, and snow *in* 60 mph winds.

Re:mdsolar strikes again

[AK Marc]

I've seen snow-proof (and ice-proof) solar panels. A very small amount of heat will melt just the lowest layer, and the snow will (if unimpeded) slide off. Cleaning the panels off for a tiny fraction of the power they collect.

Re:mdsolar strikes again

[rtb61]

The problem here is infrastructure design and it's vulnerability to inclement weather. Perhaps they should consider revising infrastructure design and start putting buildings over major routes. Not only will this protect access routes, private and public (private vehicles, trucks and trains) but also energy and communications built into those structure. By distributing accommodation, residential, commercial, retail and light industrial along and above major access route leading from points of major value to points of major value (mining, farming, leisure and manufacturing) you reduce constriction points by distributing demand along its length and at distributed focal points.

Of course in the US nothing at all will be done, as it is all tax cuts, tax cuts, tax cuts and collapsing infrastructure with dreams of bankrupting government and privatising the assets for cents on the dollar and then, gees, the idiots haven't really thought beyond that point, perhaps fighting like rabid dogs over the scraps of a once was empire.

Re:mdsolar strikes again

[jklovanc]

Even variable pitch wind turbines have a max speed. It is called the cutout speed;

Gamesa's wind turbines are equipped with a variable pitch technology. This technology allows for feathering the angle of the blades for each wind speed, whereby controlled extraction is made of the maximum energy in the wind flow. Thus, in below normal conditions the pitch is tailored to derive the maximum energy potential, and in above normal conditions the pitch is altered to derive a controlled amount of energy, so that the machine produces the rated power in a controlled and stable manner up to cut out wind speed.

Re:mdsolar strikes again

[OhPlz]

The snow is light-weight powder and we haven't had a thaw/freeze cycle, so when the wind hit makes no difference. Only about half of the roofs have been flat. There's a huge multi-building apartment complex down the street from me that evacuated because one building did have a roof collapse. The roof was nearly as pitched as my own. A number of others in other towns with similar style roofs have had the same problem.

Wind can relocate snow, but high wind doesn't mean roofs or anything else gets cleared off. It just means the snow gets put wherever nature feels like it. Get some gloppy slushy snow and that stuff will stick to anything like glue. Your panels would be doing about as good as our roofs, which isn't very good. The best part is that houses with panels would have to bear the weight of the roof, the weight of the panels, plus the weight of the snow. Not to mention the wind when it really gets ripping up here will want to tear those panels right off. Wind gets strong enough here to remove roofs if there's enough imperfection in them, or shoddy maintenance, or stuff attached to them that wasn't meant to be there.

Re:mdsolar strikes again

[OhPlz]

Ever drive in a snow storm? It refreezes. Constantly.

Re:mdsolar strikes again

[AK Marc]

What do you think the AK in my name stands for?

Would you like to try another question?

Re:mdsolar strikes again

[AK Marc]

The OP said "a very windy snowstorm " not a very windy day after lots of snow.

Re:mdsolar strikes again

[Anonymous Coward]

Check under the "You may like to read:" links on the story's page. One of those links usually goes to the submissionas page. In this case, http://tech.slashdot.org/submi...

Unreliable nuclear plant down for snowstorm

Re:mdsolar strikes again

[OhPlz]

It was windy the whole time. But what the fuck would I know, I just live in the area.

Re:mdsolar strikes again

[OhPlz]

AK47 seems most likely. Gun nut. Possibly a libertarian.

BTW, we're seeing more snow than you. Please come get it.

If you do actually live in Alaska, you must not go outside much. The second you stop moving in traffic everything refreezes. You must have magical snow.

Re:mdsolar strikes again

[Hognoxious]

By his own admission, he just does whatever the vehicle in front does; he claims it's safer. So as long as he can see tail-lights 20 feet in front of him he's fine.

Re:mdsolar strikes again

[Anonymous Coward]

Utterly delusional. Why don't you come to Boston and inspect some solar panels and pointy roofs. Snow does not work that way.

A pointy roof will be able to avoid carrying more than a few feet of snow, and will have a way for the meltwater to drain (though there is the "ice dam" problem).

Now you know. And knowing is half the battle.

Re:mdsolar strikes again

[AK Marc]

Yes, it's so magical in AK that the Eskimos have hundreds of words for snow. How does something re-freeze at -40? It never un-freezes. Why does it freeze in traffic? Does your heater not work if you aren't moving? In Alaska, it's cold. You don't turn your heater on, or if you do, you turn it on your feet. So long as your windshield stays below freezing, no snow will ever accumulate on it.

Have you ever seen snow?

Re:mdsolar strikes again

[AK Marc]

Are you lying about some argument you lost with me a long time ago? I don't remember it, or you, so I have no idea what you are talking about, so I can only assume you are lying to try to get the last word a few years after the conversation ended. Are you one of the idiots that would come back to elementary the next day with a comeback for a comment nobody remembers from the day before? If you are that slow, it's better to just try to remain unnoticed, than to announce it. One would have thought that by age 12 you'd have figured that out, so you are what, 9?

Re:mdsolar strikes again

[AK Marc]

So you are saying that it was so windy that the wind turbines in the area were all shut down?

Re:mdsolar strikes again

[AK Marc]

Ice dam is indicative of incompetent engineering. In cold climes, a "cold roof" is a better option. This consists of having the plywood base of the roof be under the studs, not above, and has almost no effect on the heat-trapping of the attic, but allows air to flow under the roof so that the roof is always ambient temperature. This eliminates the possibility of ice damning. For greater cost and complexity, there are the roof heaters for those who live in incompetently engineered homes.

Now you know, and knowing is half the battle.

Re:mdsolar strikes again

[ultranova]

So the windy snowstorm will cause the windmills to fail? How is that?

Windspeed variance (wind blows slower near the ground than high up to do drag) across the rotor causes twisting forces, which destroy the bearings. To prevent this, the rotor needs to be locked still in high winds.

Re:mdsolar strikes again

[AmiMoJo]

A lot of people on Slashdot like to paint nuclear as the solution to all are problems, but as stories like this demonstrate it does have limitations. If this were a renewable energy source there would be endless comments about how people advocating its use were really advocating more coal to back it up, and how it would never work because it isn't 100% reliable, and how we can't build many more because there are only so many locations in the US and NIMBYs will lawsuit it to death etc.

In other words there are interesting points to be discussed, but both sides are so polarized and focused on logical fallacies that it's nearly impossible to have a good debate.

Re:mdsolar strikes again

[Anonymous Coward]

I think mdsolar may have some skin in the game.

Best to ignore him as a shill in my personal opinion.

Re:mdsolar strikes again

[Anonymous Coward]

Yes it should have been the headline, but then again you would not get the idea that the nuclear plant was dangerous which is what he wanted you to think in the first place, despite being wrong about it. The fact that you are about 10000x more likely to die in a plane crash, the safest way to travel, does not dawn on such an elf.

Re:mdsolar strikes again

[fnj]

That was perfectly obvious as ONE of two reasons. So? Do you have any point whatsoever?

Re:mdsolar strikes again

[fnj]

And there is zero chance for a nuclear holocaust when a solar array stops outputting. None of that nasty decay heat whatsoever. No emergency cooling measures necessary.

Re:mdsolar strikes again

[fnj]

Bit touchy?

Re:mdsolar strikes again

[fnj]

That depends a lot on temperature conditions. If it is right around freezing, even with frightful winds you get horrendous sticky snow, and icing which is even worse. Spend a winter on Cape Cod. Spend THIS winter on Cape Cod.

Re:mdsolar strikes again

[fnj]

Only in an imaginary unicorn world can you eliminate the POSSIBILITY of ice damming. Lower the probability, sure, but eliminate, just no. When the ambient temperature itself is flirting with the freezing point you've still got problems.

Re:mdsolar strikes again

[Mr D from 63]

The point is that 1) the grid is predicted to have problems due to the storm, and 2) the plant is being shut down in anticipation of grid problems, but the headline says neither.

Re:mdsolar strikes again

[yusing]

He probably wouldn't post something about a 'renewable' going offline

I guess since that's been the tactic of the Nuclear Industry since inception (no lead-lined coffins to be found anywhere), perhaps he's just learned from the pros.

And hey, at least when renewables go offline, they don't throw temper tantrums.

Re:mdsolar strikes again

[yusing]

he has a history of posting "facts" with no further comment or context.

Much as the Industry has a long history of posting "Myths" without further comment or context. Once again, sauce for the goose ...

Re:mdsolar strikes again

[Anonymous Coward]

Wind turbines shut down when there is any really significant wind. The wind we've had around here lately would destroy any turbine.

Re:mdsolar strikes again

[Anonymous Coward]

An attic is supposed to be well ventilated in order to keep the roof cold as you say.

I've not seen a roof with plywood under the studs. What goes on top of the studs? A metal roof? More plywood?

Re:mdsolar strikes again

[Anonymous Coward]

So your solar panels have a heater constantly pumping heat onto them? Because I've certainly seen where the partly melted snow freezes back up on the windshield, and that's with heat blasting the glass.

Re:mdsolar strikes again

[JeffAtl]

Yes, it's so magical in AK that the Eskimos have hundreds of words for snow.

That's actually a myth. Like German, the Eskimo language attaches modifiers to the subject.

Re:mdsolar strikes again

[phorm]

Seems to be a backfire to me. I'm actually happy that they're cautious enough to go offline in such a scenario.

Re:mdsolar strikes again

[Anonymous Coward]

I live down the street from Pilgrim - believe me, there are plenty of steep roofs that are covered with 12+ inches of snow after the storm this past weekend - and that's *with* the strong wind gusts blasting the powder everywhere.

Off of a local road the other day, I saw someone trying to clear snow off of some panels at a small solar farm. He wasn't having a whole lot of luck.

Re:mdsolar strikes again

[Anonymous Coward]

Ice dam is indicative of incompetent engineering. In cold climes, a "cold roof" is a better option. This consists of having the plywood base of the roof be under the studs, not above, and has almost no effect on the heat-trapping of the attic, but allows air to flow under the roof so that the roof is always ambient temperature. This eliminates the possibility of ice damning. For greater cost and complexity, there are the roof heaters for those who live in incompetently engineered homes.

Now you know, and knowing is half the battle.

You can't just handwave away a real problem. Whatever you want to call it engineering wise, lots of homes in the real world suffer ice damming.
Want drive through Maine and tell people "Hey, I noticed your home is incompetently engineered, you should fix that"? You'll learn lots of different ways to say "No shit" without words.

I don't know what you were trying to argue above, that solar panels won't collect snow??
EVERYTHING DOES! Deck railings, trees, pointy roofs, flat roofs, you name it.

Re:mdsolar strikes again

[AK Marc]

It's a partial myth. The big lie in the myth is that English has one word for snow. I've seen more than that. Snow. Flurry. Blizzard. Slush. And others. It's just for triviality, someone pretended that all the words for snow in English didn't exist.

Re:mdsolar strikes again

[AK Marc]

Depends on the roof design. You can spend more in materials on a cold roof than hot. I guess that's why all the cheap bastards are complaining about ice dams now. It's not like it was unknown at the time. They just bought a crappy house.

Re:mdsolar strikes again

[OhPlz]

How does something re-freeze at -40? It never un-freezes. Why does it freeze in traffic? Does your heater not work if you aren't moving?

Sure it does. The cabin of the vehicle gets warm therefore the windows get warm. When you slow down or stop, the wind tunnel effect goes away and it accumulates. If it accumulates too much, it lowers the temperature of the glass enough to freeze. Same thing with body panels. You can leave the defroster running, but it is only capable of so much, the weather can exceed its capability.

I have a difficult time accepting that you're in Alaska. Is there some part of the state that never sees cold weather? Anyone anywhere in New England could describe all of this the exact same way.

Re:mdsolar strikes again

[AK Marc]

The cabin of the vehicle gets warm therefore the windows get warm. When you slow down or stop, the wind tunnel effect goes away and it accumulates.

So when you are moving, it unfreezes? How is that? When I'm moving, the air (well below freezing) is cooling the window faster than the heater can heat it. Only when stopped is the heater capable of melting anything.

Perhaps the problem is that people in New England see snow at temperatures above freezing. Something that was quite common when I lived in the lower 48. In Alaska, it gets cold enough, that you don't have the re-freeze problem unless you are talking about a flat driveway that's heated, which is rare, as they are quite popular with people with 20-degree drives, undrivable when icy, but flat drives don't need it.

And everyone is picking a different problem to indicate that I've never seen snow.

I don't turn on the heater when it's cold. It will melt or partially melt things, but it'll re-freeze if I drive fast, or turn off the car. It's better to let the windshield stay below freezing and no snow can stick.

Re:mdsolar strikes again

[OhPlz]

So when you are moving, it unfreezes? How is that?

It doesn't. You clear the snow and ice off before setting off. The defroster or heater keeps it from refreezing with the help of the slipstream of air helping to keep the stuff from accumulating on the glass. You slow or stop, it can accumulate, it becomes more than the defroster or heater can handle, it freezes. Maybe once you're moving the wind plus the defroster can knock it loose, maybe you have to pull over and scrape it off again, maybe the wiper fluid will help if it doesn't just make it worse.

In Alaska, it gets cold enough, that you don't have the re-freeze problem

You don't get road slop from treated roads from other vehicles? I've been up to Canadian provinces where it's ungodly below zero and the same problems exist.

 

I don't turn on the heater when it's cold.

That could be the big difference between you and everyone else. I'd rather deal with the windows than freeze.

Re:mdsolar strikes again

[Anonymous Coward]

Methinks you have never built a roof. Studs are part of walls. Do you mean rafters? Ceiling joists?

Re:mdsolar strikes again

[toddestan]

Around here, typical new construction makes sure there is a decent sized gap between the roof and the ceiling under it. Dump a bunch of insulation on the ceiling, and then put plenty of vents in the attic. The idea is that keep heat from escaping into attic as much as possible, but make sure that any heat that makes it up there doesn't linger (same with humidity). I've never seen plywood on the bottom side of the rafters.

Ice dams are still possible and can happen. For example, snow melts in the sun, and the water runs down to a shaded part. One thing no one pays any attention to anymore when building is how the house is oriented with regards to the sun, prevailing winds, etc.

any spin there?

[lophophore]

That plant is not known for being run well.

More likely, they wanted to shut it down to cover their asses in case something bad happened, e.g. storm surge. Not a bad idea, considering.

Re:any spin there?

[jonnythan]

Storm surge? It's 4 degrees in Plymouth right now.

Re:any spin there?

[Mr D from 63]

That plant is not known for being run well.

A quick Google on Pilgrim Capacity Factor yields a spreadsheet that shows 6 recent years of operation with an average capacity factor of 90$. That is quite good.

Re:any spin there?

[Mr D from 63]

RE I meant 90%, not 90$

Re:any spin there?

[Anonymous Coward]

More likely, they wanted to shut it down to cover their asses in case something bad happened, e.g. storm surge. Not a bad idea, considering.

I would say the shutdown is a non-issue.

They are almost certain offsite power will be lost, so it makes sense to shut it down.

Otherwise, they'll probably have to go through the expense of burning massive quantities of backup fuel that more than make up for any lost revenues from generation and still shutting it down after the storm has severed it from the grid.

Re:any spin there?

[towermac]

You sure? They did say 'too cheap to meter' at one time.

Re:any spin there?

[Mr D from 63]

Actually, that is a myth perpetuated by critics with no real point, and repeated by idiots that think it is clever. The industry never made such a claim. But, if you logic is that if a single statement from a single person, taken out of context, can be shown to not be accurate that proves some kind case, then you will find that nothing on this planet is credible.

So, please make a real point.

Re:any spin there?

[towermac]

That might have been a lame joke, but then you're not that much fun at parties either, are you?

Re:any spin there?

[Mr D from 63]

Oh man, I totally missed it......Sorry, sometimes I get caught up in it. I can laugh at myself for that one.

Re:any spin there?

[lophophore]

a storm surge comes with the eye or wind wall of a cyclone coinciding with the high tide. It causes extreme high tides.

temperature does not have anything to do with it, at least above 0F, the typical freezing point of seawater.

The U.S.A. is now a third world country

[Anonymous Coward]

This is the second time this season the plant has been shut down due to storm conditions. On January 27 the facility was taken offline after the two main power transmission lines were knocked out by blizzard conditions. Although the transmission lines were restored within a few days, the plant remained offline until February 7 at which time it was reconnected to the grid.

Holy hell, it took roughly 11 days to repair the power transmission lines? Did anyone die from the cold?

If such a thing happened in Canada you can be sure we wouldn't take over a week to repair the government-owned power lines.

Re:The U.S.A. is now a third world country

[Anonymous Coward]

If such a thing happened in Canada you can be sure we wouldn't take over a week to repair the government-owned power lines.

https://en.wikipedia.org/wiki/...

Right...

Re:The U.S.A. is now a third world country

[Anonymous Coward]

I would like canadians a lot better if the majority of you that i see are spewing shit about canada being better than the US

We get it. We know. There's not a thing we can do about it.

Re:The U.S.A. is now a third world country

[Anonymous Coward]

AC above just proved that the parent is full of shit, eh? I even think that the parent post wasn't even made by a Canadian, eh?

Re:The U.S.A. is now a third world country

[BarbaraHudson]

I guess your reading skills are not up to snuff. It did NOT take 11 days to repair the transmission lines. You even quoted it - "Although the transmission lines were restored within a few days".

I went through the ice storm of 98 - a month with no power. 25 people died of hypothermia.

Re:The U.S.A. is now a third world country

[BarbaraHudson]

Probably someone suffering from cabin fever because it's -21, or -32 with the wind chill up here. Canadian winters absolutely suck. Heck, even Poland and Germany are above freezing today.

Re: The U.S.A. is now a third world country

[Anonymous Coward]

Die from the cold? Probably, there's always some idiot out there or some poor soul, or whatever

But no, overall grid power was fine. This power plant, perhaps they were just cycling through some maintenance while they had a chance.

Re:The U.S.A. is now a third world country

[Anonymous Coward]

This is the second time this season the plant has been shut down due to storm conditions. On January 27 the facility was taken offline after the two main power transmission lines were knocked out by blizzard conditions. Although the transmission lines were restored within a few days, the plant remained offline until February 7 at which time it was reconnected to the grid.

Holy hell, it took roughly 11 days to repair the power transmission lines? Did anyone die from the cold?

If such a thing happened in Canada you can be sure we wouldn't take over a week to repair the government-owned power lines.

I had some Chinese food tonight.

Your fortune was in a cookie :

You will be diagnosed with anal cancer this year.

Re:The U.S.A. is now a third world country

[dbIII]

Maybe taking advantage of the shutdown to do a bit of inspection and maintainance turned up something that took a while to fix. I'm sure a few people on this site have experience of a server that had been on for over a year with no problems but would not power back on after a full shutdown and cold start. Mechanical systems can act that way as well, especially if there is a bit of heat involved and the size difference between parts when cold or in operation is significant.
I've seen a wide variety of broken components in even well run thermal power plants (I've never worked with nukes but anything after the water is heated is pretty similar). I've seen even more on the way to breaking and getting cut out before they can fail.
So to sum up I don't think there's much to take away from a single outage - if all you've got is outage times you'd have to get statistical with more info before a sensible judgement.

I went through the ice storm of 98 - a month with no power. 25 people died of hypothermia.

A month and a serious death toll, that does indeed suck. I'd wonder why they didn't truck in a pile of the container sized generators or a similar disaster plan as done by utilities after hurricanes.

Re:The U.S.A. is now a third world country

[X0563511]

That certainly was a fun experience. I use the term "fun" loosely.

One of the trees in the front yard exploded. The trunk just... blew. Wood shards everywhere. Not to mention all the transformer lightshows to rival a 4th of July celebration!

Re:The U.S.A. is now a third world country

[Anonymous Coward]

My power (western Ontario) was out for a 10 day srtech last winter. The one before that, 7 days. I, and everyone in my neighborhood, keep a generator.

Re:The U.S.A. is now a third world country

[TubeSteak]

Maybe taking advantage of the shutdown to do a bit of inspection and maintainance turned up something that took a while to fix.

Entergy's Pilgrim plant has been consistently ranked by the NRC as one of the worst in the country.

It's much more likely that Entergy took advantage of the shutdown to fix things they should have taken care of a long time ago, but refused to deal with, because the plant could be unprofitable in the near future and they're trying to milk as much profit out of it as possible. It'll all show up in some NRC filing(s) sooner or later.

Re:The U.S.A. is now a third world country

[angel'o'sphere]

I'd wonder why they didn't truck in a pile of the container sized generators or a similar disaster plan as done by utilities after hurricanes.
Because it is 'the states'. They have no 'they' there. The only 'heroes' doing anything 'active' (proactive even) are the fire fighters.
Look at the (non) evacuation of New Orleans. Hu? You could use a school bus to evacuate people? No, that is not in the competence of the majour to 'confiscate' school busses and/or to press drivers into service to rescue people.
Where do you believe emergency generators would/should come from to deploy in every town/area after such a blizzard event?
It is so typical USA. Never being prepared for anything, because that involves 'government', and it seems everything is so corrupt in the USA it would never work even if you where prepared. But as soon as something happens the President is telling everyone how he is fixing that actual crisis ... wow, in hindsight there is always money and resources (somewhat) but you can never be prepared?

Not even in a run down country like Greece stuff like this would ever happen.

Re:The U.S.A. is now a third world country

[dbIII]

Where do you believe emergency generators would/should come from to deploy in every town/area after such a blizzard event?

Another area where they don't need them at the moment - just like the firefighting gear. I get your point that FEMA or whatever does not have their shit together like the fire fighters who even share their stuff between countries in the off season.

Re:The U.S.A. is now a third world country

[dbIII]

Good post. I'm tempted to quote it to libertarians as an example of why their small government/I've got mine bullshit is insane, but that would end up sending loonies in your direction.

Re:The U.S.A. is now a third world country

[fnj]

Could you please stop sending it down here? How about we send a lot of 110 F, 100% humidity air up there next summer?

Re:The U.S.A. is now a third world country

[yusing]

If such a thing happened in Canada

Don't worry, we can still send Jimmy Carter up there again to help you guys out with ur nukes, eh.

Re:The U.S.A. is now a third world country

[Anonymous Coward]

Holy hell, it took roughly 11 days to repair the power transmission lines? Did anyone die from the cold?

No, because the power grid is redundant and losing a plant doesn't knock it off end to end.

Re:The U.S.A. is now a third world country

[BarbaraHudson]

Generators from all over north america were trucked in. Unfortunately, that takes time, especially when you're trying to make up for the loss of 16,000 megawatts of transmission capacity from James Bay (almost 10 Pilgrim nukes) and further losses from other sources.

They also took diesel-electric locomotives off their tracks and drove them on the streets to where they could be hooked up to the mains. That's enough juice for a small town.

Re:The U.S.A. is now a third world country

[BarbaraHudson]

All nice and good, but this took place in Canada. The continent was scoured for generators - anything available was shipped in - but that takes time, especially when I saw city roads that had to be scraped free of more than a foot of ice with a bulldozer, and 15,000 troops helped out.

Re:The U.S.A. is now a third world country

[BarbaraHudson]

No thanks - being at 45 degrees latitude it gets HOT in the summer (especially in traffic), and being a big island in the St. Laurence, very humid.

Re:The U.S.A. is now a third world country

[rhazz]

To be fair, the comparison you are doing here is:

This story: "two main power transmission lines were knocked out"
1998 ice storm: "over 1,000 transmission towers collapsed"

This is not apples to apples...

Re:The U.S.A. is now a third world country

[rhazz]

Or rather, it is comparing a basket of apples to an orchard of apples...

Re:The U.S.A. is now a third world country

[rhazz]

A month and a serious death toll, that does indeed suck. I'd wonder why they didn't truck in a pile of the container sized generators or a similar disaster plan as done by utilities after hurricanes.

Actually they did. Even moreso, citizens who had their power restored early then donated or lent their own generators to areas that needed them. I actually recall a at least one person being upset because their generator was never returned. Also while they say the 25 deaths were "primarily" hyptothermia, some of the deaths were caused by CO/CO2 poisoning and fires because people brought their barbeques inside to heat the home.

Re:The U.S.A. is now a third world country

[angel'o'sphere]

Don't know why terms like liberals and libertarians etc. show up all the time.

I doubt anyone outside of the USA has an idea what americans do mean with that :D

Somebody shut the snow machine off!

[The New Guy 2.0]

We could have a replay of this event as the Boston area is dealing with a similar weekend storm this week too.

Re:Devil's advocate

[The New Guy 2.0]

The "national gird" is set up so they can handle the loss of a plant or two (or maybe even three) without disruption, it just causes the online plants to spin up stronger. If your power company is claiming to be National Grid, they're indicating that they're sometimes using power from outside the area they serve.

Re:Devil's advocate of the Devil's advocate?

[peon_a-z,A-Z,0-9$_ !]

However, in this case, the customers don't lose power because the generation isn't there. Customers would lose power because the grid fails. Entergy has power from other sources or purchasing agreements to make up for this temporarily.

Similarly, it is unsafe (and illegal, technically) to run your nuclear powerplant with no access to the grid. If you have a coal plant that gets disconnected from the grid, you'd shut it down too with no way to generate revenue from burning additional fuel.

Devil's advocate to your misguided devil's advocate...The problem is the electrical grid not the source.

Nuclear plants don't like sudden shutdowns

[ZombieEngineer]

Sounds like this is a "preventative measure".

Normally there is some time between neutron capture and actual nuclear fission (I have heard a figure of 15 minutes). This means that even if the control rods are slammed in when the power transmission lines were cut the previous heat load would still be generated for a period of time. Often this means resorting to drastic measures to reduce the neutron flux to zero ASAP (certain salts are added to cooling loops which achieve this but requires a good flush to get rid of).

Controlled shutdown means the reactor can be restarted in "a couple of hours"
Emergency shutdown means the reactor can be restarted in "a couple of weeks"

Burnt once, twice shy...

Re:Nuclear plants don't like sudden shutdowns

[Shakrai]

This means that even if the control rods are slammed in when the power transmission lines were cut the previous heat load would still be generated for a period of time.

The cooling system is designed with such considerations in mind. The plant isn't going to melt down even if you cut the transmission lines directly at the plant and have to quickly power the reactors down. The line about "a potential loss of offsite power" is perhaps more telling, they use offsite power to operate the control mechanisms and cooling systems if they have to shut the reactors down, though one would presume that they also have UPSes and diesel generators on site.

Re:Nuclear plants don't like sudden shutdowns

[rmdingler]

Absolutely. Entergy has multiple options to power the grid, and this was a sane, safe way to react to another bout of record snowfall.

But hell, if you put it like that, there's no controversy.

FWIW, I an a big fan of renewable power generation too, but I recognize that we're not there yet for reliable grid electricity generation. The nuclear option should not be off the table.

Re:Nuclear plants don't like sudden shutdowns

[Mr D from 63]

Emergency shutdown means the reactor can be restarted in "a couple of weeks"

Absolutely not true. It can restart rather quickly, it depends on the reason for shutdown.

And beside that irrelevant point, don't forget that nuclear plants all over the north-east have kept running reliably through the recent rash of heavy winter storms. The shutdown at Pilgrim is because of reliability issues with the local transmission/distribution network and expectation that it will go down.

Re:Nuclear plants don't like sudden shutdowns

[Mr D from 63]

Yeah, snow covered solar panels and windmills shut down during blizzards aren't much help in these conditions. We need diversity.

Re:Nuclear plants don't like sudden shutdowns

[Dan East]

But that has nothing to do with the generation of electricity, only the generation of heat. Surely the system can simply bypass the generators when the power is not needed. The cooling towers and ponds cool the steam / water back down before cycling back into the reactor anyway, regardless of whether the generators are part of the loop or not. An "emergency shutdown" of the reactor should not be necessary just because the electricity is not needed. Sounds like they think there is a high probability of a significant part the grid going down and not requiring all of the available power generation, so they're saving money by shutting it down now and shifting production to the natural gas / coal plants (which can be "turned off" and "turned on" much faster, to save even more money when the grid goes down).

Re:Nuclear plants don't like sudden shutdowns

[Mashiki]

Emergency shutdown means the reactor can be restarted in "a couple of weeks"

When we had that massive power outage around the great lakes a few years back due to the transmission line issue. Bruce Nuclear here in Ontario did an emergency shutdown. It was back up and running in 8 hours after the initial outage.

Re:Nuclear plants don't like sudden shutdowns

[AK Marc]

Yes, that was the problem with Fukushima. The design guaranteed a meltdown in the case of loss of power. If you lost mains power, and your generator didn't start, you have a 100% chance of a meltdown. The tsunami took out the mains and the generators. So a meltdown was guaranteed, because they didn't restore power. Nothing else matters from that point. If they had requested a generator and fuel from someone and gotten it in the 12 or so hours the batteries lasted, then we'd know for sure whether the loss of containment was guaranteed by a breach caused by the earthquake. But Japan never asked, so nobody even tried.

I'd assume that the plant in question is of a similar design.

What I'd do is that because a meltdown makes more than enough power for a secondary, smaller generator to make enough power to prevent a meltdown. Sort of an active-verson of a passively cooled reactor. But cost and liability are more important than safety.

Re:Nuclear plants don't like sudden shutdowns

[Shakrai]

One would assume that a snowstorm isn't going to destroy the on-site backup generations as a tsunami can. This seems like an overabundance of caution to, though IANANP, and if the grid can absorb the shutdown I suppose there's nothing wrong with excessive caution. There's a bit in TFA about them doing maintenance that required a shutdown during the last forced shutdown, so maybe they're planning to do the same here rather than do it over the summer months when energy prices and demand are higher.

Since you bought up Fukushima, I've long wondered how a modern first world nation-state could not manage to get generators on-site before the batteries went flat. I've read that the utility tried but could not get them there in time due to traffic jam and destroyed infrastructure on the ground. Did nobody think of picking up the phone and calling someone at the military to dispatch some bloody helicopters? I can't fathom that you need so much power to run cooling pumps as to render the required generators too heavy to fly in.

Re:Nuclear plants don't like sudden shutdowns

[Anonymous Coward]

The design guaranteed a meltdown in the case of loss of power.

Damn ... that means we can't even sue the designers for breaching their guarantee. Clever ... very clever.

Re:Nuclear plants don't like sudden shutdowns

[Xylantiel]

Even if they had gotten the generators, you can't just rewire things on the spur of the moment like that, especially not when a significant section of the country has also been wiped out. Of course if they had proper hardened vents like are required in the US, there wouldn't have been any explosions. Still would have been a technical loss of containment due to the necessity of venting, and probably still a meltdown, but the destruction of the outer containment and cooling systems by the explosions was the real disaster.

Re:Nuclear plants don't like sudden shutdowns

[TechyImmigrant]

>FWIW, I an a big fan of renewable power generation too

Sometimes renewable energy comes from a big fan.

Re:Nuclear plants don't like sudden shutdowns

[AK Marc]

Since you bought up Fukushima, I've long wondered how a modern first world nation-state could not manage to get generators on-site before the batteries went flat. I've read that the utility tried but could not get them there in time due to traffic jam and destroyed infrastructure on the ground. Did nobody think of picking up the phone and calling someone at the military to dispatch some bloody helicopters? I can't fathom that you need so much power to run cooling pumps as to render the required generators too heavy to fly in.

I didn't want to say, because it sounds like the "depend on the US" cliche, but I could have driven to work, chained up a generator (not sure what they needed, but I had a 40kVA that I could have sent), and driven it to a C130 (nearby military base) and gotten it on the ground in Japan well under the 12 hours battery they had (presuming the US military would give civilian aid). Then arrange some helicopter transport to the site.

My understanding is that Tepco lied to everyone. They lied about it being under control, and whether it would be "saved" and what they needed and such. An international call for generators, and I'm sure there are hundreds (or thousands) that could have come from South Korea in time, even if they couldn't find a single one in Japan. And there would have been many options to getting it there. Tanks don't mind mud so much, and you can hook a civilian trailer to one. So tow the damn thing. On the road, where you can, on the shoulder where you can, over fields and through houses where you have to. It's a fucking nuclear meltdown.

But Tepco said "it's under control". "There was an incident, but it's currently contained". At least that's how I understand it from the information I saw released. Everyone with a "C" in their job title should be in jail, or working from the reactor floor.

Re:Nuclear plants don't like sudden shutdowns

[AK Marc]

Even if they had gotten the generators, you can't just rewire things on the spur of the moment like that, especially not when a significant section of the country has also been wiped out.

The last time I replaced the generator and UPS at the (not a real) datacenter I work at, there was about 10 seconds of downtime, and 4 hours of electrical work. Had we de-powered everything during the work, it'd have been done in under 30 minutes.

Yes, better to let the meltdown happen than take the time to wire it in the middle of a flood. But if you were right, why did they have generators on the way, stuck in traffic? The failure was they were to cheap (and afraid of people knowing how many screw ups they had to that point) to fly them on (well, under) helicopters.

Vents don't matter. If they had an underwater generator (they exist) and the fuel stored above ground, like on a small water-tower (or even on the roof of a building), then there's have been no meltdown. $10k and proper planning would have prevented the meltdown.

That's why people don't trust nuclear power. The jackasses building them would rather kill everyone with a meltdown than spend $10k to secure the backup from natural disasters considered "likely" for the area.

Re:Nuclear plants don't like sudden shutdowns

[Anonymous Coward]

Other than the shitty title of this posting, there's nothing to indicate the the plant is being "taken down" or "shut down." The statement quoted is that the plant will be disconnected from the grid to protect the plant from problems that may be caused by downstream grid failures.

Re:Nuclear plants don't like sudden shutdowns

[hankwang]

"Normally there is some time between neutron capture and actual nuclear fission (I have heard a figure of 15 minutes)."

The fact that you can detonate a nuclear bomb by bringing together two subcritical pieces of U-235 shows that this can't be true.

In a nuclear reactor, 7% of the heat output is from the decay of the fission products (alpha and beta decay). This 7% will continue to be generated regardless of control rods or neutron absorbers. It will last hours to weeks, depending on where you put the threshold for "finished". Remember Fukushima: it became a disaster when the water circulation backup pumps failed 12 hours after the reactor shutdown.

Re:Nuclear plants don't like sudden shutdowns

[angel'o'sphere]

What you write is complete nonsense.

There is no 'neutron capture' taking 15 minutes.
Either it smashes an uranium atom, that is called fission, or it is captured by boron ...

There is absolutely no difference if a reactor is shut down by emergency or 'controlled'. If it is down longer than 30 mins, the time to reactivate it is days. The reason is neutron poisoning ... or xenon poisoning, depending how you want to call it.

That means, the decaying products of the fission reaction produce so much Xenon and Boron that the neutrons of an start attempt get captured by them. Hence a new 'controlled' fission reaction is not possible, until those elements decay further.

That takes hours, up to days. This is the main reason why nuclear plants can only be used very limited for load following (if you power it down considerably, you have to make sure you either don't need it full powered soon, or you know you will power it back up VERY soon)

Re:Nuclear plants don't like sudden shutdowns

[angel'o'sphere]

There is nothing to 'rewire'. You simply connect the flown in generator to the same connections the flooded generators use.
Pretty simple.

Re:Nuclear plants don't like sudden shutdowns

[uncqual]

To be fair, you do probably have to disconnect the wiring from the flooded generators as you don't want the electricity from the temporary generators shorting to ground through the flooded generators. And, you do need to connect the temporary generators somehow and, if that contingency was not considered in the existing wiring, you probably need to do some "rewiring".

So, some rewiring may consist of bolt cutters while some may consist of clamping existing cables to the cables of the temporary generators. Neither should be a big deal for on-site electricians though.

Re:Nuclear plants don't like sudden shutdowns

[AmiMoJo]

Actually there was emergency cooling provided by fire engines and mobile pump vehicles, as per the emergency plan. A meltdown was by no means guaranteed. What caused it was the fact that a broken valve, which no-one knew about at the time due the fact that it was inaccessible and the monitoring equipment had failed because of earthquake and tsunami damage, was stuck in the wrong position so most of the water being pumped in never made it to the reactors. Instead it was found weeks later in storage tanks.

So in fact they had already implemented your plan. They had mobile pumping equipment - better than generators because even if the plant's pumps failed they had their own. They had an ample supply of fuel and water for their pumps, but like your plan it was all reliant on the emergency cooling system still being intact and able to deliver the pumped water where it needed to go.

That is the fundamental flaw with all existing plants. The emergency cooling system can be damaged, and there is no other way to pump coolant in when you can't physically get to the reactors due to a damaged plant or radiation.

Re:Nuclear plants don't like sudden shutdowns

[AmiMoJo]

See my other comments, generators were available but would not have helped. In fact they had extra pumps attached and working, but it didn't do anything.

TEPCO were confused due to the difficult situation on the ground, and didn't want to start doing press released for every bit of data that came in and creating a lot of wild speculation in the media. The surrounding area had already been evacuated and as I mentioned there was little anyone could have done to help, so there wasn't much point saying anything until they were certain.

It was still badly handled of course, but there was also a genuine belief that things were not that bad due to flawed operating procedures. Much of the monitoring equipment had failed due to lack of power and earthquake/tsunami damage, so the plan to make manual readings was put into place. That was hampered by lack of access to critical areas due to high radiation and damage to the plant. The procedures were written with the assumption that data could be relied on and that a lack of data was not a cause for action or assuming the worst. Note that TEPCO didn't write the procedures, they were standard on that type of plant.

Sticking to procedure is viewed as best practice in many industries. For example, on the bullet trains the drivers are taught to always refer to the manual. If there is any kind of fault they never rely on memory, they always open the manual and follow it step by step. They actually read out each step as they are doing it. That helps prevent mistakes, and so far they have an unblemished safety record with zero deaths or serious injuries despite constant operation since 1964. Clearly, it is less suitable for nuclear plant operation.

Basically, this is the problem with most current plants. If something goes wrong it is hard to understand what is happening, and even with experts on hand a lack of data leads to bad decisions and mistakes.

Re:Nuclear plants don't like sudden shutdowns

[DerekLyons]

What you write is complete nonsense.

There is no 'neutron capture' taking 15 minutes.
Either it smashes an uranium atom, that is called fission, or it is captured by boron ...

Not entirely nonsense, he just gets the mechanism wrong - what's actually delayed is neutron release.
 
 

That means, the decaying products of the fission reaction produce so much Xenon and Boron that the neutrons of an start attempt get captured by them. Hence a new 'controlled' fission reaction is not possible, until those elements decay further.

That takes hours, up to days. This is the main reason why nuclear plants can only be used very limited for load following (if you power it down considerably, you have to make sure you either don't need it full powered soon, or you know you will power it back up VERY soon)

You're correct in your assertion that daughter products can inhibit or delay reactor restart - but you're incorrect in asserting this is why nuclear power plants can't be used except for minimal load following. That's a design choice, not a law of nature. Civilian power plants are can't be used for load following because they're designed to run under more-or-less steady state conditions for safety and economic reasons. Naval power plants on the other hand are designed to operate as load followers because of the need to respond quickly to throttle commands and other demands on the plant. Even though they work on the same physical principles, the detailed engineering is different.

Re:Nuclear plants don't like sudden shutdowns

[angel'o'sphere]

You are wrong about the design choice.

As I explained piling up waste products prevent powering up if you have to much of them.

This is an inherent 'problem' of the technology. I suggest to google and read up how france is coping with that problem e.g.

There is no design that avoids having decay products like Xenon that prevent you from holding down the reactor in the wrong tome window. Sorry that is a /. myth. Even if it was true it would not matter, as we are talking about current reactors and why the current ones either have to power up quickly or have to wait a few hours to do so.

Re:Nuclear plants don't like sudden shutdowns

[Anonymous Coward]

In fact, the company I work for has a:
- battery room,
- a large diesel generator that is tested every few weeks,
- holes in the side of the building to pull power cables through from a generator that can be placed on the parking lot.

A junction box designed to connect an external generator and switch to it without loosing power to the building.

We just do this in the eventuality that power get lost and we can't do our work, there will be no natural disasters or loss of life if the power fails completely. It is in the Netherlands so grid-failure is extremely rare (in Amsterdam less than once every decade).

Re:Nuclear plants don't like sudden shutdowns

[DerekLyons]

You are wrong about the design choice.

[[Citation Needed]].
 

I suggest to google

You rely on Google. I'll rely on actual experience with nuclear power plants and decades of research.
 

There is no design that avoids having decay products like Xenon that prevent you from holding down the reactor in the wrong tome window. Sorry that is a /. myth. Even if it was true it would not matter, as we are talking about current reactors and why the current ones either have to power up quickly or have to wait a few hours to do so.

Google the operating history of Hanford plutonium production reactors - which were completely shut down by xenon poisoning when they were first started. Then consider modern civilian reactors - which can run for months or years without being shut down by xenon poisoning.

And then kindly fuck off. Because you have no clue what you're talking about - you're a parrot mouthing words you do not understand.

Re:Nuclear plants don't like sudden shutdowns

[angel'o'sphere]

Ofc modern reactors can run for years without Xenon poisoning.
Silly!

The Xenon poisoning happens when you _shut it down_ or _power it down_ to a lower power output level. It is kept in control during normal operation due to high neutron flux, neutrons get captured in an "stable" reaction during ordinary operation. If the neutron fux lowers, as it does when you _power down_ the reactor then Xenon is piling up.

This happens with _all_ reactors currently in use.

If you know a certain one which behaves different and is in use: point it out. Cant actually be as Xenon is a mandatory decay product in both plutonium based as uranium based reactors, so good luck!!

Because you have no clue what you're talking about - you're a parrot mouthing words you do not understand.
Unfortunately you are an idiot. I understand very well about what I talk. After all I work in that area since decades. Literature is plenty available, too. But good luck with your claim you would also work in that area. You post certainly does not support this :D

Re:Nuclear plants don't like sudden shutdowns

[DNS-and-BIND]

The U.S. DID provide a big emergency airlift for the tsunami, called "Operation Tomodachi". Thirty thousand people died and a huge area was devastated. It was big, they could have done precisely as you described. It's a sad story.

MDSolar must be disappointed...

[dfenstrate]

...that it didn't melt down. We get it, MD, you don't like nuclear power.

Re:MDSolar must be disappointed...

[bill_mcgonigle]

...that it didn't melt down. We get it, MD, you don't like nuclear power.

He probably lives in the Northeast where everybody is doing what they can to bring on some global warming.

If you think Nuclear is unreliable...

[Anonymous Coward]

... my goddamn solar system goes offline every goddamn day for HOURS AND HOURS, and always during the coldest part of these frigid winter days...

Mod parent down

[Anonymous Coward]

Parent misses the point that giving the mdsolar troll a bone every now and then encourages his behaviour.

Re:Devil's advocate of the Devil's advocate?

[RightwingNutjob]

Local power lines routed through trees. High tension lines on rotting wooden towers. Welcome to the People's Republic of Massachusetts, where the buses are always on time, the subways never stop running, and town-owned sections of the sidewalk are always the first to be shovelled.

strange circumstance.

[nimbius]

Pilgrim Power Plant in Plymouth was taken offline line Saturday in anticipation of the weekend snowstorm.

I can understand concerns about grid underservice...thats capitalism. What i cant understand is cycling down a nuclear facility because you're worried about power supplied from external source. you are a nuclear facility power is in and of your nature. This is the second time you've done this, so stop placating investors and be truthful: either the state of Massachusetts is no longer capable if funding a power grid that can endure normal weather patterns, or global climate change is an immediate concern we should all address.

Re:strange circumstance.

[peon_a-z,A-Z,0-9$_ !]

Nuclear plants of the design mentioned in the article must legally have offsite power to continue operation. As soon as offsite power is lost, the plant is required to shutdown. An emergency shutdown is more paperwork than a planned shutdown such as this.

The reason for this is that in an accident scenario, you would like to rely on offsite power to run your emergency coolant pumps for this particular design.

Newer reactor designs don't have this issue, but this is a pretty economic decision considering an emergency shutdown if/when the offsite power does eventually trip. The grid seems pretty unreliable based on past experience, as the article even notes.

Re:strange circumstance.

[fuzzyfuzzyfungus]

Nuclear power plants generate net positive energy(or they wouldn't be power plants at all); but they still have numerous systems(from relatively important sensors, control systems, pumps, etc. down to boring stuff like the bathroom lights) that need to be powered to work properly. They do have backup generators on site; but, for reasons of safety(and because it's hard to sell the output of a plant that isn't connected to the grid) you aren't supposed to run them when they have been disconnected or are expected to be disconnected.

Nuclear plants are a trifle more dramatic, because shutting them down isn't just a matter of not shovelling more coal into the furnace; but it's my understanding that no power plant types are really supposed to be run off grid. Even a perfectly well behaved design is still a waste of money if the power can't reach customers, and nobody likes depending on backup power to keep every electric device in the facility online.

They might well need to review the qualify of the grid connection, if only because an idling nuclear reactor is a punchy opportunity cost; but there isn't much reason to leave it on. (Unless you managed to get the NRC drunk and obtain approval for a madcap scheme to convert the reactor to a snow-melter for the duration of the storm. We really are starting to run out of places to put the stuff, and a nuclear reactor would be very well qualified for melting duties.)

Re:strange circumstance.

[TapeCutter]

What i cant understand is cycling down a nuclear facility because you're worried about power supplied from external source

Does the phrase "fail safe" ring any bells?

Re:strange circumstance.

[Joe_Dragon]

to bad MB wanted to much to melt the snow.

Please explain...

[TapeCutter]

How does using FF stop bad weather from taking out transmission lines?

Re:Please explain...

[ColdWetDog]

You can burn little pots of diesel fuel under the power lines to melt the snow. Like they do in Florida to keep oranges warm.

Try that with nuclear!

Unreliable indeed

[mdsolar]

Unreliable refers to Pilgrim's sorry history. http://www.patriotledger.com/a... It is typical of Entergy's "fleet."

Re:Unreliable indeed

[Mr D from 63]

Pilgrim's capacity factor, even on a bad year, kills anything solar could ever dream of. Pilgrim is at the bottom of an elite group of plants that perform best in the power industry. Its all relative.

Re:Unreliable indeed

[cyberjock1980]

What's funny mdsolar is that your last 6 posts (and counting) have been to *this* story, and every single one (except one) is rated a 0, or -1, 1/2 of them are identied as "troll".

The one exception post... the one I just replied to.

Hahaha. Sounds like you got exactly what you deserve for your ignorance.

Re:Unreliable indeed

[angel'o'sphere]

'Capacity' factor is a word that is only used in the climate denier scene and recently by marketing droids.

A plant has no capacity factor. It has a 'load utilization' measured in hours, where 100% is ~8600 (the amount of hours in a year).

But thanx for spreading your ignorance.

Re:Unreliable indeed

[angel'o'sphere]

That is not funny, but sad reality of the /. modding 'community'.

I guess he will challenge the modding and if the supervisors figure it was abuse, the modders get deprived of their ability to mod, for ever.

Hahaha. Sounds like you got exactly what you deserve for your ignorance.
I guess the ignorant guy is you. Click on him and check his posting history :) (I doubt anyone will ever do that on your idiotic posts, though)

Re:Unreliable indeed

[Mr D from 63]

Capacity factor = equivalent hours generating at rated capacity during a given year divided by the number of hours in the year. It is a very common measure for electrical generating plant performance and reliability. If you had simply done a web search you would not have looked so stupid in your response.

Re:Unreliable indeed

[LordLimecat]

'Capacity' factor is a word that is only used in the climate denier scene and recently by marketing droids.

I know you have a massive anti-nuclear streak, but lets be real here. Solar couldnt cope with the storm either, gets awful generation during winter especially at latitutes where these types of storms are common due to insolation, and cant provide base load.

Nuclear on the other hand has caused-- past, present, and anticipated future-- FAR fewer deaths than hydro or coal. Heres a question for you: Do you protest as vigorously when a new hydro plant opens? Because a single dam event around 20 years ago killed ~triple the number of people expected to die from Chernobyl, and well over double the number of people who have died or are expected to die from nuclear since its inception till now.

A plant has no capacity factor.

From the Energy Information Administration:
Capacity factor is a measure of how often an electric generator runs for a specific period of time. It indicates how much electricity a generator actually produces relative to the maximum it could produce at continuous full power operation during the same period.

For example, if a one megawatt generator produced 5,000 megawatthours the entire year, its capacity factor would be 0.57 or 57%

In fact they provide capacity factor information for various technologies if you so desire.

Im really not sure where you get your information but it seems terribly off.

Re:Unreliable indeed

[fnj]

Er, math check. There are 8760 hours in a year. 8784 in a leap year.

Re:Unreliable indeed

[fnj]

Commiseration with mdsolar. There are a whole lot of really clueless assholes with axes to grind moderating on slashdot.

Re:Unreliable indeed

[Anonymous Coward]

Oh boo-fucking-hoo. What's wrong? Getting so pissed that you are leaving your mommy's basement to cry to her because of the ass kicking you got from your downmods on /.? Get a fucking clue, it is what you are saying but how you are presenting your fucking information dumbfuck poster child of why abortion should be legal. FWIW, I fucked your mommy good and hard last night while you were jacking off to a photo of Richard Stallman and she loved it so much she not only wants me to return but also wants to kick you out on the street. Since you are hated by everyone as the downmods prove you will remain on the streets till you starve to death. Oh, you will be kicked out once you get to your mommy.

Re:Unreliable indeed

[angel'o'sphere]

Yes, I know? And? Was my quickshot out of my mind: 8600 hours to unprecise for you?
At my age I unfortunately need a calculator to calc 24*365 precisely in my mind ... or well, actually not, but I'm out of practice.

So thanks for pointing out the obvious :D

But now I see the nice decreasing line of numbers: 876 ... I guess I can memorize that. Astonishing that I never noticed that as I'm working in that business since decades.

Re:Unreliable indeed

[angel'o'sphere]

As I said before, this is a relatively new "factor" brought in during the AGW discussion.

As I also pointed out, (in various posts) the energy industry is not using this "metric" as it is pointless for any decisions.

The problem basically is that laymen believe you can simply set up two "57% capacity factor" plants and then you have up to 114% power available. Obviously you can have as many PV solar plants as you want and have no solar power at night.

No idea why a .gov site suddenly uses that term, too. Likely because the editors are laymen :D In the energy company I work for, no one is using it (and no database contains a field with that name, or a different name with that meaning).

Re:Unreliable indeed

[angel'o'sphere]

No, it is not a common measure at all.

It is a measure that came up the recent ten years in the AGW discussions especially in the USA.

I work in the power industry. That term is not used at all by any power company in Europe I'm aware of.

Reason: it is meaningless for every operation a power company does.

The term got invented by "anti renewable" protagonists who want to have a nice easy number to squash down on.

However it is spreading now, I admit even GE uses it now (wrongly ofc) in its marketing brochures for wind turbines.

If you had simply done a web search you would not have looked so stupid in your response.
I suggest that to you :D Easy to figure that I'm right.

Re:Unreliable indeed

[Mr D from 63]

Don't be ignorant. Its been used long before Global Warming was even talked about. We used it in the 80s and 90s.

http://www.eia.gov/tools/faqs/...

Re:Unreliable indeed

[angel'o'sphere]

I don't see a date on your link :)

Anyway, the term is irrelevant for plant owners/operators. No one uses it in the energy company I worked for, and I never saw it in any european publication.

And I really doubt it was used in the 80s or 90s in the USA.

Care to explain a situation where it makes sense using 'capacity factors', except calculation the ROI of a wind mill?

Re:Unreliable indeed

[Mr D from 63]

Here is an article written in 1995 that uses capacity factor, and if you used a little effort you could find more, I found this in one quick google. It is a standard term, and a useful measure. You can find it defined in IEEE and other standards, and has been used for quite a long time.

http://www.hks.harvard.edu/hep...

You can choose to "doubt", but that would be willful ignorance.

Capacity Factor is quite useful in determining ROI for a windmill. If you know the average capacity factor, you know how much electricity the windmill would likely produce in a year, and therefore how much $$ you would make on power sales in a year.

Re:Unreliable indeed

[Mr D from 63]

No one uses it in the energy company I worked for,

You know everything everybody at your company used? Impressive. OK, tell me what performance measures your asset management group did use then.

Re:Unreliable indeed

[LordLimecat]

That "metric" is provided by every national agency that studies / regulates energy. I linked you directly to a .gov address, which indicates that it comes from a US federal agency.

Im also not interested in what the "industry" says, Im interested in the facts as compiled by reputable agencies. The facts show that solar is a great supplement, and that nuclear is the most cost effective and scalable energy source if you want "carbon neutral". If you dont, it falls back to coal and natural gas.

The problem basically is that laymen believe you can simply set up two "57% capacity factor" plants and then you have up to 114% power available.

I dont know of anyone who thinks that. Capacity factor simply means you may have a 1GW nuclear plant-- that is, at peak it can generate 1GW (what its rated at)-- but over the course of the year it may generate an average of 700MW/h for every hour of the year. This would represent a 0.70 capacity factor.

If you have 2 0.57 capacity factor plants, you will get 114% of the capacity of one plant, or 0.57 of the two combined.

No idea why a .gov site suddenly uses that term, too.

Ive been having these discussions for years, and linking to the same wikipedia articles for years which use that term. Some quick googling indicates that its been tracked since at least the 90s for at least coal power. Theres a good article on it here.

Re:Unreliable indeed

[angel'o'sphere]

As I said before: this term is first of all an american term and secondly a NEW term since the AGW discussion came up.

Capacity Factor is quite useful in determining ROI for a windmill. If you know the average capacity factor, you know how much electricity the windmill would likely produce in a year, and therefore how much $$ you would make on power sales in a year.

Yes, laymen believe that.
Care to explain how you figure the capacity factor of a wind mill? And after you have figured it, why don't you use the raw data, that lead you to that figure instead of the CF? Wow ... I guess you don't know how to figure CPs correctly, does not matter.

Figuring an ROI is the only thing you can do with a CF, but it is much more easy and straight forward to actually use the expected power generated instead.

Does not make any sense to figure my windmill with 10MW yield will produce 40GWh per year and that is .... erm, let me check, if it was 100% it would be 87,6 GWh, so lets divide it wow, it is 45%.

So and now to figure how much energy I will produce I have to take the yield of the plant per year and multiply it with the CF, which is 87,6 GWh * 45% which is 40GWh.

Wow, surprisingly after I know that my plant will produce 40GWh, I for fuck sake don't need the CF for anything anymore!!! It is a useless number!

But well, I guess that was to easy ... and please spare me the idea that a wind plant has a CF of less than 45%. Baltic I and Baltic II, two wind parks in the Baltic sea, run by my ex employer have a CF of 250%. Wow, contradicts your 'knowledge' doesn't it?

Anyway, no one uses CFs in real life, as I said before they only pop up in web articles mainly written by laymen.

If you built a windmill at a place where it has not a CF of 100% you must have good reasons for that ...

Re:Unreliable indeed

[angel'o'sphere]

Yes I do.

As I was the main "architect" in an reengineering project where all data bases got "unified" and a glossary about all terms used in the energy business was established.

OK, tell me what performance measures your asset management group did use then.

No idea. That does not belong to the energy production department :D nor to energy sales.

Also your question is pretty vague, performance of what?

Re:Unreliable indeed

[angel'o'sphere]

My point is that the metric is
1) useless.
2) rather new
3) not really relevant for power companies

Power companies don't measure a power plant with a CF. A CF does not help you in any way to plan how much power you want to generate tomorrow with your fleet of plants. It does not help you in any way to plan the plants in question for the rest of the year, their maintenance etc.

The only conclusion you could draw from long term CFs is by comparing two plants of same technology and figuring one is more down than the other ... but even that you do by a term called "load utilization".

Re:Unreliable indeed

[Mr D from 63]

Its clear you don't know what the fuck you are talking about. I am done.

Re:Unreliable indeed

[Mr D from 63]

So, you have no clue that asset management uses, but claim to know that you would have heard of performance measures such as capacity factor.

You don't know what the fuck you are talking about. Just stop and quit making a fool of yourself. You probably don't even know what asset management folks do.

Re:Unreliable indeed

[angel'o'sphere]

I know what I'm talking about, pfft.

I worked over ten years in that area. And likely will be agin in future :D

Re:Unreliable indeed

[angel'o'sphere]

Capacity factor is not a performance measure.

So far you did not tell me what kind of performance measure you are interested in.

There is/are no asset management folks ... but we have janitors and dispatchers :D if that is what you mean.

There are three main things counted for power plants:
o power produced (raw production and own usage)
o fuel used
o cost

This is visualized in a kind of spread sheet with 25 columns
First column is the power plant (block) name, the rest ore numbered from 1 to 24 for each hour of the day.
Obviously you have a row for every plant. And a sum.
Every hour can be displayed as four quarter hour values. If the value did not change it is obviously the same every 1/4 hour.

So, there is obviously no capacity factor involved ...

The exact same view is used to plan my schedule for tomorrow, with the difference that the sums are already filled and I adjust my fleet of plants in a cost effective way to get the required sum.

If you want to know that stuff I suggest to work a year or two in the industry and stop insulting people that actually did that.

Re:Unreliable indeed

[Mr D from 63]

You can't even use CF properly after I showed you the definition.

Re:Unreliable indeed

[Mr D from 63]

Capacity factor is not a performance measure.

Add that to the list of ignorant, stupid things you post here. That is exactly what CF is, a performance measure.

And with that, you confirm that you are not only ignorant in the energy area, but also most likely making fraudulent claims regarding your experience. At the very least, it explains why you no longer work in the industry.

Re:Unreliable indeed

[angel'o'sphere]

The definition is simple. Maximum production (capability) divided by actual production.

Thank you. As I pointed out, and you seem to reject to follow my argumentation, so you don't grasp it, no one in the industry uses that metric. The metric we use is either "load utilization" or: the actual produced power. Percentages are irrelevant.

I suggest strongly to check what a "load profile" or a "load curve" is. As the demand on the grid is changing over day, a plant that "technically" has a CF of 95% or more, can't yield 95% of its rated capacity all day because it has to follow actual demand. That is true for minimum 50% of all plants a power company has in use. So: having any numbers like your beloved CF are irrelevant for planning my tomorrows plant schedule ...

Re:Unreliable indeed

[angel'o'sphere]

Sure, if you don't want to listen. That is your problem.
I gave you now enough examples: WHY CF CAN NOT BE A PERFORMANCE MEASURE, and you keep ignoring it.

Good luck in your career, and I sincerely hope you once work in the power industry and then you figure: oh my gosh, Angelo was right!

At the very least, it explains why you no longer work in the industry.

How idiotic are you? I'm a free lancer ... wow, another super simple explanation why things are not as you think they are.
Good luck in your career! You need it. Jumping to simple conclusions is not very helpful in an high tech environment :D

Re:Unreliable indeed

[Mr D from 63]

Any one that says "100% Capacity Factor" in the context you used it in is just plain ignorant to how it is used to start with. Please stop embarrassing yourself.

It is quite easy to adjust for load demand, if needed, why you didn't realize that is quite amazing given your claimed expertise.

Re:Unreliable indeed

[Mr D from 63]

You continue to embarrass yourself. Even if I showed you how it is clearly defined as a performance measure, you would deny what I present, or make some weaselly excuse, so why should I even bother?

Re:Unreliable indeed

[angel'o'sphere]

Of course it is easy to adjust to load demand.

But according to your logic it corrects the CF downwards.

So a coal plant that is load following (as in: not a base load plant) will have a CF of less than 50%. (Because it will be 8h down over night and then vary over 16h between 50% and 90%)

The same coal plant used as base load plant will have a CF of 90%.

So, the CF is meaningless ... or how do you explain that the exact same plant has a different CF depending for what I use it? (And I really don't want to know what CFs are listed in your magical list of american coal plants :D )

is just plain ignorant to how it is used to start with
Still your mistake that you don't grasp: CF is not used at all in the power industry. Hence there is no ignorance involved on my part, but plenty of it on your part. The annoying thing however is that you did not read what I posted or somehow rejected it and did not try to understand it.

Again, if you missed it: to plan my schedule for my power plants tomorrow, I use the ACTUAL power they will generate. Per hour! Because the projected demand tomorrow will change: per hour. I don't use a projected "name plate" value and multiply that with a CF. Why? Because I NEED the concrete number of MW a plant will produce at 10:00 at 11:00 at 12:00 etc. I don't CARE if that is done by a plant that has a CF of 50% or 95% ... CFs never ever show up in any planning or settlement calculations.

If you believe otherwise, why don't you show one? You believed that in Asset Management you need it, can't be so hard to find a spread sheet showing that you are right! Actually, as you are not right, you won't find any ... but you could try to see that I'm right :D

Re:Unreliable indeed

[Mr D from 63]

You just don't understand the concept, because it is a well established performance measure.

And, you don't even seem to understand how to predict performance. The best single thing to predict performance is????

I'll give you a hint... its two words.

Re:Unreliable indeed

[angel'o'sphere]

No one is predicting performance.

Only you want to do that.

I have a coal plant yielding 1GW (4 blocks with 250MW each).

I want to use that tomorrow to produce 800MW between 8:00h in the morning and 20:00h in the evening.

What exactly do you want me to predict? I simply give the plant operator a schedule to power up the plant so that it is at a 800MW level in time (8:00) and power it down after 20:00.

There is no magical CF involved.

If the plant dispatcher has the authority to trade at the energy market he has 20% of the plant capacity left over for trading.

It is as simple as that. Good luck in your continuous ranting. Insulting other /. posters does not really make you look bright, so good luck in that, too.

Re:Unreliable indeed

[Mr D from 63]

I new you could not answer the question, a question that even a young inexperienced professional could answer. I'll ask again, and even clarify where it shouldn't have been needed, but no matter because you'll avoid answering, I'm sure.
....
The best single thing to predict performance, of any kind, is????

Re:Unreliable indeed

[angel'o'sphere]

The answer you seek is not there, get over it and face that you have no clue about energy production.
No idea why you insist anyone would use a CF for 'predictions' when the owner of the plant exactly knows 'whith out predictions' how much power the plant is producing.
But thanx for not even trying to understand the simple concept :)

Re:Unreliable indeed

[Mr D from 63]

Let me answer it for you;

"Past Performance"

and performance measures, like CF and others, are quite useful in that regard, and for other uses as well. Case Closed.

Re:Unreliable indeed

[LordLimecat]

Power companies don't measure a power plant with a CF. A CF does not help you in any way to plan how much power you want to generate tomorrow with your fleet of plants.

Capacity factor is a compiled statistic from past data. It is useful for determining the performance of a particular form of energy, and for predicting future output. If for the past 20 years your 20MW solar farm has gotten a 0.2 capacity factor, its a pretty safe bet that you're going to generate somewhere in the range of ~4MWh every hour of the year.

Plants arent "rated" in capacity factor because it isnt a static piece of datum. If you have 5 nuclear plant shutdowns over the year, that will impact that year's capacity factor.

You're essentialy arguing that statistics like the GDP are worthless because theyre not a hard, fixed number. But compiled statistics like the GDP measure past performance and are a good measure of relative strength of a country; in the same way, capacity factor combined with "cost per mwh" and "average plant size" are very helpful for understanding what scale of generation we are talking about. If I tell you that a 1GW nuclear plant was just built, that really doesnt help you determine how much power it will likely produce unless I also tell you that nuclear plants in the area generally hit 0.65 capacity factor.

The reason people bring it up with solar is because solar averages an extremely low 0.2 capacity factor. So when someone mentions that a 10MW solar farm was built for ~1/100th the cost of a 1GW nuclear plant, it sounds really viable (equal cost per MWh)-- until you realize that the solar farm will generate, on average, 1/3rd the power of the nuclear plant because solar has an inherently lower capacity factor.

Re:Unreliable indeed

[angel'o'sphere]

No, I'm arguing that a CF is worthless.

As it is not helpful in any way to plan power generation for a big power company that has more than a single plant.

I gave enough examples for that in my other posts.

If I tell you that a 1GW nuclear plant was just built, that really doesnt help you determine how much power it will likely produce unless I also tell you that nuclear plants in the area generally hit 0.65 capacity factor.
E.g. that is nonsense. As I as the plant owner have full control (besides accidents) how much power I want to create with it. I can run it as a base load plant at 95% for 5 years ... obviously I then have a nearly 95% CF. Or I can run it as a load following plant, that varies its out put from 40% over night to 95%. Then my CF is about 55%.

The reason people bring it up with solar is because solar averages an extremely low 0.2 capacity factor.
Absolutely irrelevant. No one is using that number, not even one who is building a new plant. It is only "helpfull" (I doubt that)/ "interesting" (perhaps) for laymen to get an idea how much they need to invest if they want to have a solar plant with a certain yield.

I as a power plant owner are absolutely not interested in that number. What I want to know is the MW (not the CF) the plant will produce tomorrow at a certain point in time, considering the weather report for tomorrow.

And when I'm running the plant tomorrow, I want the yield in MW life forecasted (that is called a prognosis) using various weather services that give me an hourly updated localized fore cast for that plant. My software actually transforms such forecasts directly into MW yields, using the properties of the plant (like orientation, declination, max yield etc.).

The only thing a dispatcher of a fleet of plants is interested in are actual MW/GW yields. No one who actually is working with power plants is using a CF (well, no one might be exaggerated, in the USA many people do dumb things all the time, no idea if there are power companies that indeed find using a CF useful)

1/3rd the power of the nuclear plant because solar has an inherently lower capacity factor.
Irrelevant. Completely irrelevant. The main difference between a solar plant (regardless if PV or thermal) is: it is not dispatchable. If anyone uses a CF for serious comparison he makes a mistake.

Re:Unreliable indeed

[angel'o'sphere]

Past performance, as I explained to you, is measured in actual MW yields, actual fuel spends, actual water levels, actual money spent and actual money earned etc.

There is no CF involved as the CF can not be used for anything meaningful a power plant owner is doing with his plant.

Yes, case closed. As I explained the mechanics and economics how plants are operated now several times. If you have problems grasping my explanations, perhaps I'm not good in translating my knowledge into english, then ask questions.

Reiterating over your misconceptions makes them not true.

Re:Unreliable indeed

[Mr D from 63]

Well, here is your statment, your words;

'Capacity' factor is a word that is only used in the climate denier scene and recently by marketing droids.

I proved this to be a statement of ignorance. You then felt compelled to backpedal and shift the discussion to other performance measures. There are many performance measures, and they have their uses. They are tools. You don't say "a wrench is useless because it can't drive a screw". But that is they type of argumentative logic you are trying to pass off, and that is why I largely ignore it. I know perfectly well there are a variety of performance measures and tools. You can pine away at them all day, and I can add more.

But, back to the whole point of your original contention, it was simply ignorant, case closed.

Re:Unreliable indeed

[angel'o'sphere]

I proved this to be a statement of ignorance
No, you did not prove anything, except perhaps that I'm right.
You then felt compelled to backpedal and shift the discussion to other performance measures.
That is wrong. You asked about performance measures. Need me to link your inquiry?
and that is why I largely ignore it.
I guessed that. That is the reason you don't learn :D

The original point was: CF is not used in the power industry (my stand point).
CF is used in the power industry (your standpoint).

I explained why it is useless in the power industry.
You gave fluffy comments why it should be used as it looks so interesting for you on paper.

I carefully explained how you plan a day ahead with your plant, and you easy can extend that to a month ahead (longer timeframes for planning rarely exist). Obviously a CF is not helpful in both scenarios. So even you should easily conclude that no one is using a not helpful metric.

I repeat: the metric showed up a few years ago, as you gave reference probably around 1995, it is mainly used to ditch the usefulness of renewable plants as on paper a 20% CF of a solar (PV) plant looks really bad in comparison to a 95% nuclear plant. Neglecting the fact that the first plant is designed to produce power when it is needed (mid day) and the second one is designed to run for years at the same level.

So: tomorrow I need 1GW extra around noon. Do I power up the nuclear plant from 95% to 104% to get that? No, because that is only 111MW and not a GW. Do I power up the solar plant? No, it powers up itself. I actually power down the nuclear plant to 85% and get the rest of the energy from my solar plant.
Which CF was helpful in that decision? None obviously. To figure how much power I feed into the grid tomorrow at noon, I need to know how much power both plants in question produce tomorrow at noon. There is no CF available to calculate that.

So again: in my daily business decisions a metric like CF is irrelevant, hence no one is even attempting to calculate it.

The only point where you are right is the calculation of ROI for a planned Solar or Wind plant. But then again: as soon as you have the prognosed amount of power, why would anyone in his sane mind calculate a CF from that? It is a self fulfilling formula: "max yield" (nameplate yield per year) / "yield according to weather conditions (per year)" -> CF. Now I get something like 40%. or 20%, who cares. Now to do a prognosis of the yield for next year I do a multiplication: "max yield" * CF. Wow: surprisingly the result is exactly the same I got in the division above as a divisor. (*facepalm*) WTF should I calculate a damn CF, when I have the prognosis of the yield for next year as a hard number?
All plant planing works with hard numbers like that.

Re:Unreliable indeed

[Mr D from 63]

Two of your ignorant quotes;

Capacity' factor is a word that is only used in the climate denier scene and recently by marketing droids.

It is not a performance measure.

Capacity Factor is a standard industry measure that has been used for quite some time. Here is an ANSI/IEEE standard from way back in 1987 which clearly defines Capacity Factor under Performance Indexes. You cannot deny this unless you are an utter fool.

http://www.scribd.com/doc/1688...

Unfortunately, you will still deny it, and continue with your willful ignorance. For that reason I will no longer read any of your replies, but I might just keep reminding you of your ignorant contention.

Re:Unreliable indeed

[angel'o'sphere]

Thanx for linking the PDF. So I stand corrected that there is an american standard that defines the term. Nevertheless my claim that the term is not used in planning for power production stands.

The pdf defines Gross Capacity Factor and Net Capacity Factor, I'm indeed surprised about that. Note: "Net capacity factor calculated using this equation can be negative during a period when the unit is shutdown. Formeaningful pooling of data on several units, net capacity factor can be deïned to be zero when the unit is shutdown." From the PDF. So, obviously that factor varies over time and is hence as - I mentioned, if I may point out, useless for any practical planning purpose.
Nevertheless: the PDF is from 1998 not from 1987, based on older versions from 1980, who knows if there was a "capcacity factor " mentioned at that time. Furthermore except for "defining" the two terms, the terms are not further used, so it is unclear what the purpose is.

Anyway, regarding the term and its usefulness, or lack there of I give you a simple problem to solve.

I have two power plants, a PV solar plant, which I call S, and a dispatch able plant, does not matter if it is coal or any other variable source, which I call D. Both have a maximum yield of 1GW.

Tomorrow from 9:00 AM till 04:00PM (16:00) I'm supposed to feed exactly 1GW into the grid.

Note, local noon is 12:30, so it is easy to figure when solar has its peak production. Please tell me how much power I feed in each hour from each plant. We simply assume we have a clear sky and perfect conditions for the solar plant.

You can assume what ever CFs you feel convenient. I would ofc stick to (your) the previous introduced CFs like 0.2 for S and 0.85 for D ... if that helps you :D ... or was it 0.65 you mentioned for D?

Example:

                  08:00 | 09:00 | 10:00 11:00 ....
Total: 1GW | 1GW | 1GW
S: xMW | yGW | zGW
D: XGW | YGW | ZGW

Should be a no brainer that no CF will help you in filling that table.

Anyway if you find an example how american plant operators actually use the term CF then I would give you points.

Re:Unreliable indeed

[Mr D from 63]

The standard is from 1987, it is right in the title "ANSI IEEE-762-1987". You again show ignorance, now ignorant on how standards are revised, again proving your contentions about your experience are false, that is why I won't be reading any more of your bullshit. You should stop making a fool of yourself.

Two of your ignorant quotes;

Capacity' factor is a word that is only used in the climate denier scene and recently by marketing droids.

It is not a performance measure.

Capacity Factor is a standard industry measure that has been used for quite some time. Here is an ANSI/IEEE standard from way back in 1987 which clearly defines Capacity Factor under Performance Indexes. You cannot deny this unless you are an utter fool.

http://www.scribd.com/doc/1688...

Unfortunately, you will still deny it, and continue with your willful ignorance. For that reason I will no longer read any of your replies, but I might just keep reminding you of your ignorant contention.

Re:Brittle

[cheesybagel]

France seems to handle their plants fine. And wind power and solar power have capacity factors so low than it won't work for grid generation without excess generation capacity and storage to begin with.

Both the top news you posted here and your second link in the parent post are about transmission grid failures. Not nuclear power plant failures. As for graceful powering up and down it can be done. France for example has nuclear power plants with load-following mode. The US doesn't bother with this because the faction of power generated with nuclear is low enough that it isn't worth doing the retrofits. As for the heat sink being too hot you would have the same problem with any other thermal power plant which uses a cooling tower. Coal, natural gas, whatever. It isn't a nuclear power specific problem either. It's a thermal power plant issue.

They could have splurged when it was built --

[Anonymous Coward]

and paid for a "ROOF" - that way when it snows, it could keep running....but noooo... :)

Re:Devil's advocate of the Devil's advocate?

[epyT-R]

The People salute you for your commonwealth's stewardship, comrade!

Relative terms.

[jklovanc]

Relative terms can be missleading. The slowest cheetah is still much faster than the fastest turtle. While it may be among the worst nuclear plants it is still extremely reliable. From the article you referenced

Pilgrim performed at nearly 97 percent capacity in 2014

Re:Relative terms.

[AmiMoJo]

Reliability includes how many safety issues were identified and had to be fixed outside the normal maintenance cycle. It also includes how many times the reactor had to SCRAM unexpectedly, which is a rather expensive operation both for the plant itself and the owners who have to cover the sudden loss of hundreds of megawatts of output on the energy market.

Re:Relative terms.

[jklovanc]

Which is all taken into account in the 97% figure. In this case all your doom and gloom scenarios caused a less than 3% decrease in output. Similar things happen to solar and wind installations too. Low wind or high wind days shut down wind farms and clouds decrease solar output. Take a look any any real life production graphs and you will see that, while it is predictable, wind and solar is not dispatchable. One can not turn the sun or wind up when one needs it.

Re:Relative terms.

[amorsen]

Take a look any any real life production graphs and you will see that, while it is predictable, wind and solar is not dispatchable. One can not turn the sun or wind up when one needs it.

Which is exactly the problem with nuclear power as well.

Re:Relative terms.

[jklovanc]

You really need to know how conventional power works before you comment. No nuclear plant always runs at 100% capacity. There is always a reserve that can be utilized if needed. When one plant goes down other plants increase production to compensate. When the down plant comes back on the other plants decrease output. Solar and wind are usually used completely to their capacity. If you don't use wind/solar power you lose it. Weather/time of day is the governing factor in how much electricity is produced by wind/solar. Human choice governs how much power is produced by nuclear. There is a big difference.

Take a look at this report about the problems with integrating solar into the grid.

Re:Relative terms.

[amorsen]

Insults do not help your arguments.

If you don't use nuclear power (once the power station is built) you lose it. Exactly the same as solar and wind. You can turn solar and wind off if you want, exactly the same as nuclear power, but economic reasons make it infeasible to do so very often, again exactly the same as nuclear power.

Nuclear power is notoriously difficult to integrate into the grid; you need a lot of fossil fuel or hydro plants to handle the peak load that nuclear cannot handle economically.

Re:Relative terms.

[jklovanc]

Insults do not help your arguments.

Calling you on your lack of knowledge is not an insult. It is fact. Then you immediately prove my point.

If you don't use nuclear power (once the power station is built) you lose it.

Nuclear reactors have control rods which are used to regulate the output. You can run a nuclear plant at any percentage of maximum capacity as you want at any time of day or year. Wind and solar are regulated by weather, season and time of day. In effect you get what you get. You really need to understand what dispatchable generation is. Nuclear is dispatchable. Solar/wind is not. Dispatchable power can be regulated to provide power when it is needed. Non-dispatchable power does not have that ability to control output. Nuclear power is very different than solar/wind.

Nuclear power is notoriously difficult to integrate into the grid; you need a lot of fossil fuel or hydro plants to handle the peak load that nuclear cannot handle economically.

Again you are pulling statements out of the air. If your statement is true then how can France produce over 80% of their power using nuclear reactors.

You completely ignore the report about the duck graph. It shows how reliance on PV panels can cause an problem at dusk when PVs stop producing and conventional has to take over. If that slope gets too step then conventional power may not be able to compensate for the rapid loss of PV power.

Power lines

[rossdee]

Maybe if they put Power lines underground they wouldn't come down every time there is a storm, which seems to be twice a week in New England

Re:Power lines

[Anonymous Coward]

I've heard an estimate of x25 in cost to put power lines underground vs above ground on pylons. Who would pay ?

Re:Entergy

[Anonymous Coward]

Bias revealed. Submitter hates Entergy.

Low hanging fruit.

[Anonymous Coward]

Unreliable refers to Pilgrim's sorry history

From the linked article: "Pilgrim Nuclear Power Station in Plymouth will continue to be classified by the federal government as one of the worst performers among nuclear power plants in the country, at least for now, based on a recent inspection."

Which invites the question of how the best nuclear power plants in the country are faring?

Re:Low hanging fruit.

[Luckyo]

Likely pushing close to 100% load utilization. This one is apparently sitting at 97%, which is considered fairly low for a properly maintained nuclear plant which are usually around 99%.

They murder everything else on the numbers though, because that's what nuclear power plants do.

Re:Low hanging fruit.

[fnj]

To be fair, let's also point out that it is a huge headache shutting down a nuclear plant for any reason, and every shutdown adds a little bit of a chance for a disaster. That contributes to bad decisions.

Re:Low hanging fruit.

[Anonymous Coward]

Yo, I heard Chernobyl managed actually beat those numbers by getting over 100% load. I guess that makes it even better in your books!

Re:Low hanging fruit.

[Luckyo]

Same applies to any large plant. Spinning down and spinning up turbine unit alone can take a day.

But it's worth it because of just how economical these large units are due to economy of size.

Re:Low hanging fruit.

[Luckyo]

I know that you think you're being a smartass, but you should really look up what the terms used actually mean, rather than what you think they mean.

Then you won't like like a dumbass to others.

Mod Parent Down

[Anonymous Coward]

This post may contain factual INFORMATION. Quick mod this down as a TROLL!!!

It was for grid stability reasons

[Anonymous Coward]

Actually, emergency or not, reactors have to be shut down for a few days. Just like they were in the case when power lines went down. When reactor shuts down, it is T-0, irrelevant of reason. It needs to wait for a few days until all the Xe-135 decays.

http://en.wikipedia.org/wiki/N...

These things need to decay before you can restart. If you try to be cleaver about it, especially with bad reactor designs, you end up with Chernobyl. Literally. (And if you don't understand what the above means, don't try to spin this as some sort of "nuclear is dangerous" bullshit. It's the same as cooling blast furnace at a smelter - you can't speed up cooling by using things like water, or you'll cause an explosion and people will die - it doesn't mean blast furnace is unsafe!).

So if you shut down proactively, and power lines go down or another plant goes down, you can restart the nukes as soon as power lines are repaired and before other plants are ready, if those suffer damage from the storm. All they did was proactive shutdown of excess capacity to deal with possible grid disturbances later. Imagine if grid connections collapsed to 2 other power plants and the nuclear plant, but nuclear plant grid could be repaired within a day but others took weeks.

This was done to increase reliability of the grid after the storm, not because of "omg, nukular plant and storm". Shameful on mdsolar that he tries to spin proactive action relative to grid stability as something that has anything to do with any single power plant.

Or you can just wait....

[Anonymous Coward]

Wait for it.... Tsunami !

SyntaxError: invalid syntax

[Anonymous Coward]

Too bad MB wanted too much to melt snow. What do they teach the kids in school these days?

Re:Brittle

[Uecker]

France has to shut down nuclear power plants every few years when there is a heat wave in Europe. Google is your friend.

The problem with load-following is economics. Nuclear power is already uneconomical. Load-following does not help.

Re:Brittle

[angel'o'sphere]

It isn't a nuclear power specific problem either. It's a thermal power plant issue.
Ofc it is! Since when can a coal plant melt down?

Your wind/solar nitpicking is idiocy. Who cares about 'capacity' factors as long as a plant yields energy when it is needed or is planned for?

Actually, no one in the industry uses that term. It is only used by marketing droids after fanboys like you made it popular in the internet. The term used by power companies is load utilization, and it is not measured in % ... up to you to figure. Google might (or might not) be your friend.

Re:Brittle

[Luckyo]

Not only is nuclear power economical, it's currently by far the most profitable investment you can make in a lot of countries.

Here in Finland, the best private investment in terms of ROI are nuclear reactors at Loviisa, followed by nuclear reactors at Olkiluoto. Everything else is far behind those. This is because once you repay the debt on the plant, you have about 50-60 years of pure profit with minimal expenses in comparison to amount of energy you can sell. And those plants were built several decades ago, so they're basically printing money for the owners right now.

Of course we have a functional infrastructure, reliable grid and ability to sell power to all of our neighbours which helps profitability of nuclear power plants with ~99% load utilization significantly.

Re:NRC ranks Pilgrim among worst US nuclear plants

[uncqual]

Of course, if the United States has nine or more nuclear power plants, nine of them will be "among nine of the poorest performing nuclear plants" -- even if those plants have a exemplary record and exceed every safety requirement. If the United States had exactly nine nuclear power plants, each of them would be "among nine of the poorest performing nuclear plants" AND "among nine of the best performing nuclear plants"

Uh, OK

[cascadingstylesheet]

"Nuclear plan takes reasonable - or possibly even excessive - precaution." Eek. My skirts are all aflutter ...

Re:Entergy

[towermac]

Yeah, but that's like hating Verizon or Monsanto.

He may be on the wrong side of the nuclear debate, but the only people that like Entergy are Entergy execs.

There's no need to

[Anonymous Coward]

Morons like yourself will always, even when it's nothing to do with shutting down or failure of a renewable power station, bleat on about "it's unreliable! what will you do when the wind stops, huh?".

Posting a cutout of a nuclear power station IS required. And again it's morons like yourself that make it a requirement. You appear to think that only renewables demand backup power, nuclear never. Therefore this incident which indicates that nuclear needs backup MUST be pushed forward so that there's even a TINY chance of it breaking through your idiocy that all power stations are unreliable and require backup.

You are whining about this because you don't want to consider nuclear unreliability.

who cares?

[Anonymous Coward]

This isn't news.
Why do I even visit this site anymore...

97% of load while operating.

[Anonymous Coward]

However it's out of action for maintenance or failure for about 40% of the time.
      DAWES report includes many nuclear power plants assessed for utility.

Plymouth

[Anonymous Coward]

Oh!... Plymouth in the US somewhere (apparently the Northwest, according to comments above). So not the Plymouth in the South West of England then. Okay, no worries - no snow coming our way, carry on...

(it would be nice if USians would realise most places in the US are named after places in and around the UK, the remainder are mostly taken from more native sources and so sound a bit different.)

Re:Brittle

[radl33t]

Here in Finland, the best private investment in terms of ROI are nuclear reactors at Loviisa, followed by nuclear reactors at Olkiluoto

Source? I was under the impression Olkiluoto #3 was a colossal failure and 300% over budget. Oh yes, from wikipedia,

"Unit 3, an EPR reactor, is still under construction, but various problems with workmanship and supervision have created costly delays which have been the subject of an inquiry by the Finnish nuclear regulator Säteilyturvakeskus (STUK).[1] In December 2012, Areva estimated that the full cost of building the reactor will be about €8.5 billion, or almost three times the delivery price of €3 billion.[2][3] A license for a fourth reactor to be built at the site was granted by the Finnish parliament in July 2010,[4][5][6] but discontinued by the government in September 2014. TVO has the option to reapply for the license in the future.[7]"

Are you claiming at 300% over budget it has the among the best ROI? I mean even in Finland you could build out solar energy with a better ROI than a $10/WAC nuclear plant (or gas, oil, wood, steam, wind, biomass) nothing costs this much except a nuclear boondoogle.

Deaths by hydro or coal?

[phorm]

Out of curiosity, what deaths have hydro caused?

Re:Deaths by hydro or coal?

[chihowa]

He's probably referring to the Banqiao Dam failure in 1975, which killed around 170,000 people.

High capacity hydroelectric plants involve dams, which are incredibly destructive when they fail. Even when they don't cause fatalities, dam failures often cause massive ecological damage (aside from the damage caused by damming a river in the first place).

Re:Deaths by hydro or coal?

[phorm]

Hmm, an underdesigned dam in China initially constructed in the 1950's - with safety features reduced from what was recommended - which had issues that were patched with assistance from soviet consultants. Apparently they were also communicating by telegraph and messages were lost...

That's a lot of deaths, but also in a country with a high population (meaning incidents have higher potential fatalities).

Re:Deaths by hydro or coal?

[chihowa]

A fair analysis, but he was directly comparing it to Chernobyl, which can be described similarly (except for the population issues and the correspondingly lower death toll). The 1975 failure was also enormously more damaging because it was a cascade failure, with one initial failure causing several downstream failures.

Dam failures in general tend to claim pretty big death tolls and extremely large property damage because of the amount of stored energy and the short time over which it is released. From the few US samples available, a recent failure caused enormously more damage than the most recent nuclear incident (and the same death toll, zero).

Hell, the same earthquake and tsunami that caused the Fukushima reactor failures caused a dam to fail, which killed 7 people.

While hydroelectric power is historically a new thing, dams have been around for ages and large pools of water held back by human devices are nothing to scoff at.

Re:Deaths by hydro or coal?

[LordLimecat]

Hmm, an underdesigned dam in China initially constructed in the 1950's

Why doesnt this argument fly when people apply it to Chernobyl?

Fact is, generating energy kills people. Around 1000 coal miners die a year. Less than 500 die a year from nuclear if you annualize all expected future deaths from Chernobyl, Fukushima, and TMI. If you DONT annualize it, less than 100 die a year.

The only rational conclusion one could form from looking at the facts and listening to the arguments used against nuclear is that there is a phenomenal amount of FUD.

Re:Deaths by hydro or coal?

[phorm]

I didn't say it rationalizes it, just that it's not all that surprising.

Flawed process

[phorm]

You know, I'm not sure "we thought things were less bad than they were because we didn't even have a proper assessment process" isn't exactly a positive note in their favour.

Re:Brittle

[Luckyo]

Olkiluoto #3 is, as the name implies, the THIRD unit. Other two are the most profitable endeavours ever, after two units at Loviisa.

I can't find you the source right away, however this was a part of investigative story made by YLE, our state broadcaster. They were doing an analysis of profitability of investments, I believe as a part of their story on which of our traditional industries are competitive and which are not, and then they hit the fact that there were four extreme outliers in their statistics which were extremely profitable. Loviisa unit 1, Loviisa unit 2, Olkiluoto unit 1 and Olkiluoto unit 2.

Olkiluoto unit 3 is the experimental new reactor Areva was selected to build, and they failed at it. It's fairly obvious to even a casual observer that I could not have been talking about Olkiluoto unit 3 because it's not operating yet - as a result it can post no revenue.

Re:Brittle

[Uecker]

Olkiluoto #3 is, as the name implies, the THIRD unit. Other two are the most profitable endeavours ever, after two units at Loviisa.

I can't find you the source right away, however this was a part of investigative story made by YLE, our state broadcaster. They were doing an analysis of profitability of investments, I believe as a part of their story on which of our traditional industries are competitive and which are not, and then they hit the fact that there were four extreme outliers in their statistics which were extremely profitable. Loviisa unit 1, Loviisa unit 2, Olkiluoto unit 1 and Olkiluoto unit 2.

Maybe this is true - but is rather irrelevant. I don't doubt that some nuclear power plant built at sometime somewhere was/is profitable. Those plants have been build at a time where electricity market was highly regulated in Finland. The price of electricity is determined by the least efficient plant (in terms of marginal cost) which is needed to satisfy demand. In the past, and without much competition this may have been a rather expensive source of power. Nuclear power plants only needed to be cheaper than this plant to be a good investment. Nowadays, this is unlikely to be true even in Finland.

Olkiluoto unit 3 is the experimental new reactor Areva was selected to build, and they failed at it. It's fairly obvious to even a casual observer that I could not have been talking about Olkiluoto unit 3 because it's not operating yet - as a result it can post no revenue.

But I guess it eats all profts from the other plants.

You're both right, and both wrong.

[DerekLyons]

"Normally there is some time between neutron capture and actual nuclear fission (I have heard a figure of 15 minutes)."

The fact that you can detonate a nuclear bomb by bringing together two subcritical pieces of U-235 shows that this can't be true.

Actually, the grandparent is partially correct - he's describing what is called slow fission, and it's what makes fission reactors practical. Though to be fair, you're partially correct as well - you're describing fast fission (prompt criticality) which is what makes nuclear bombs possible. The difference between the two lies in the engineering, I.E. the presence of a moderator, the amount and type of nuclear materiel present, etc..., etc...
 
What makes you both partially correct is that there isn't a delay in fission, but a delay in neutron release.
 
  Decay heat in reactors comes partially from these delayed neutrons, partially from the fission of daughter products. (Right after shutdown, the former predominates, over time they cross over until the latter predominates.)
 

In a nuclear reactor, 7% of the heat output is from the decay of the fission products (alpha and beta decay). This 7% will continue to be generated regardless of control rods or neutron absorbers.

No. Under normal operating conditions, about 7% comes from various delayed sources - but when the reactor is shut down, the neutrons creating those sources are essentially shut down as well. Thus, over time the amount of energy released from those sources falls off over time (reaching .02% of normal operating power within a week) as the delayed neutrons are exhausted and short half life fission products decay.

Re:You're both right, and both wrong.

[hankwang]

What makes you both partially correct is that there isn't a delay in fission, but a delay in neutron release.

From reading the linked Wikipedia page, I get that the delayed neutrons are responsible for 0.6% of all neutrons emitted from fission, and most of them with half-life times between 2 and 20 seconds. While this makes for some nice control bandwidth (you can afford to be 0.6% off with the control rods without getting an instantaneous nuclear explosion), I don't see how these delayed neutrons can be responsible for the majority of the 7% decay heat.

Re:You're both right, and both wrong.

[DerekLyons]

I don't see how these delayed neutrons can be responsible for the majority of the 7% decay heat.

It doesn't all come from delayed neutrons. It's a combination of delayed neutrons, fissions due to the delayed neutrons, and decay of the daughter products. It's both in what I wrote and the Wikipedia article on decay heat which I linked to.

Re:Brittle

[Luckyo]

Actually the price of electricity in Finland is among the lowest in Europe. This is one of the chief reasons how our system works. You see, we have a lot of traditionally extremely energy-intensive industry related to forestry (i.e. paper, carton and cellulose production), metalworks (both smelting and advanced machining such as shipbuilding) and so on. As a result, one of the primary goals of the entire country's energy policy is to ensure that electricity would be as cheap as possible.

This kind of forward planning is what allows for those record profits. Not electricity prices, that are very cheap in Finland by European standards to the point that it was one of the chief reasons why most of the heavy industry stays in the country, and why modern energy intensive industries like heavy datacenters (i.e. Google) find Finland so interesting for their European operations.

Some other things you should understand before arguing on the topic of "eating profits".
1. Loviisa site is owned by a different power company, Fortum. Olkiluoto is owned by TVO. The third planned nuclear plant site is by a third company, Fennovoima at Pyhäjoki.
2. Financing in modern world is done through credit rather than through running profits.
3. Areva has actually agreed to fixed price delivery. Which is why Areva has done huge write downs for the plant. Most of the losses related to Olkiluoto 3 that TVO, the company that runs Olkiluoto site come from having no ability to produce power as planned and having to source energy elsewhere. Luckily we have solid interconnects with Russia (mainly Sosnovy Bor nuclear plant), Estonia (Narva's shale rock plant) and Sweden (Hydro across northern Sweden) to pick up the slack when needed.
4. Nuclear industry is considered so profitable here in Finland that third site by a separate company is in advanced planned stages. Fennovoima has selected a Rosatom reactor for a Pyhäjoki site just recently. To give you an understanding of how far decision making is on this, our government had anti-nuclear Green party as one of the smaller parties within it, and it ended up resigning from government when other parties, including much of opposition parties voted to proceed with the granting of necessary permits.

Re:Brittle

[cheesybagel]

I see. You didn't get it when you learned themodynamics. A heat pump needs a cold reservoir to work. Much like a car needs a radiator. It doesn't matter if the car is gasoline or diesel powered. If the radiator isn't working and providing cooling for the engine either you shut down the engine or you melt the engine. Simple as that. If it was a coal power plant you would have to shut it down as well if the cooling water became too hot. Unless you want to wreck the power plant. There are alternative cooling systems to cooling towers but they are inefficient so they are not used in large scale thermal power plants. Also as you should remember from when you learned the Carnot cycle the higher the temperature you run an heat engine the more efficient it gets. So high efficiency thermal power plants, regardless of how they generate the heat, will always operate as close to the limits of the materials as they can.

Are you claiming that wind or solar have more availability than nuclear power? Try generating solar power in the night time or wind power when there is either no wind or too much wind (which forcibly shuts down windmills to prevent break down). Anyone with two brain cells knows renewables like solar and wind have less availability than nuclear power.

Re:Brittle

[cheesybagel]

Yeah. The costs were higher because it was a prototype nuclear power plant. Besides a lot of people back then doubted Areva's construction cost estimates. Among the third generation nuclear power plants they are the most complex. The Westinghouse APs in China seem to be building more or less on schedule though. I think there was like 1-2 year delay at most.

As they get used to manufacturing these kinds of power plants the construction time and cost goes down.

Re:Brittle

[Luckyo]

I believe the biggest problem was identified as the fact that for Areva, this was actually the first project they managed on their own. Before that, another french state energy company did the top level management and coordination and Areva was more of an executor than manager.

Areva lacked know-how in this area, and that is where the biggest problem with the project lied.

Read the whole message asswipe.

[DerekLyons]

Ofc modern reactors can run for years without Xenon poisoning.
Silly!

You have the reading comprehension of used wad of chewing gum.

The Xenon poisoning happens when you _shut it down_ or _power it down_ to a lower power output level.

Absolutely incorrect - xenon accumulates in the reactor (to a level determined by a variety of complex factors) and poisons the reaction even during steady state operations, and this must be accounted for in the design of the reactor. (As I said, for an example of this, look up the first run of the Hanford plutonium production reactors - which were completely shut down by xenon poisoning.) Xenon does not magically appear or magically start absorbing neutrons just because power has been reduced or the reactor has been shut down.
 

This happens with _all_ reactors currently in use.

I never claimed that xenon did not accumulate in all reactors currently in use - I merely pointed out that the behavior of civilian reactors with regards to xenon poisoning is the result of a deliberate design choice and operating philosophies, not a law of nature. Again, consider the difference in behavior between the first run of the Hanford plants and a modern plant.
 

I understand very well about what I talk. After all I work in that area since decades.

No, you very obviously do not know what you're talking about.

Re:Read the whole message asswipe.

[angel'o'sphere]

The steady production of Xenon does not matter.
It is compensated by enough neutron production. Hence it only accumulates till a balance of Xenon versus neutrons is reached. Silly, sigh.

There are absolutely no complex factors involved. Xenon is product of the fission process, pretty far back in the line of decay.
There is no physical, fission related way to influence that.
The only thing you could influence is to get it faster out of the reactor (it is gas, you could collect it somehow, but I consider that difficult, you had to get it somehow 'out of' the fuel).
So the only way to deal with it is either to produce more neutrons 'somehow' or to reflect neutrons back into the reaction or to finetune the speed of the neutrons so that they still trigger fission but don't get captured.

Against Xenon that is piling up when you power down a reactor: you can't do anything at all. Stop claiming that nonsens, or please file a paper and farm in your Nobel price!

Laws of physics hold for you the same as for anybody else ...

When all nukes are shut down

[mdsolar]

There won't be meltdowns.

Re:Brittle

[angel'o'sphere]

I see.
You never figured how a coal plant actually works. I suggest to visit one. They have guided tours.

No idea why you jump to wind and solar in the end of your post. I know like anybody else that solar works to 100% during daytime and to 0% at night time. What exactly is your point? (That is for PV)
I also know that wind plants don't produce electric energy when there is no wind, silly! Again, what is your point?

Thanx for pointing out the obvious, must have been important to you. You where not allowed to talk much as a child, I assume? Pitty! But time to get over it. Now you can talk, are allowed to tell long stories etc. So perhaps try to tell us something that matters. Thanx for the short introduction into Carnot again. There are so many people here on /. who get that guy wrong. Btw, very small correction: the heat is not that relevant. It is the heat difference.

So you want to claim, a coal plant can melt down like a nuclear plant, if it is not cooled, I mean you still want to claim that? Silly boy ...

Are you really that stupid?

[DerekLyons]

Against Xenon that is piling up when you power down a reactor: you can't do anything at all.

I never claimed otherwise. Are you really so fucking stupid that you think I am making that claim?
 

The steady production of Xenon does not matter.
It is compensated by enough neutron production. Hence it only accumulates till a balance of Xenon versus neutrons is reached.

This is so fucked up and backwards I don't even know where to begin...

I'm done replying to you as you very obviously have no reading comprehension and no clue what you're talking about.

Re:Are you really that stupid?

[angel'o'sphere]

The guy who does not know what he is talking about is you.
I never claimed otherwise. Are you really so fucking stupid that you think I am making that claim?

Of course you did. That is the whole topic of our discussion.
But nice you admitted now that you where wrong.
I'm done replying to you as you very obviously have no reading comprehension and no clue what you're talking about. Sorry, that I'm not able to read between your lines. I knly read what you write, might be my fault. Regarding, not knowing what I'm talking about, I believe I made crystal clear that I in fact do know what I'm talking about.

Have a nice day.

That NOT how it works in the movies

[adam_j_bradley]

That's not how it happens, that's not how any of this happens...

Re:Brittle

[Uecker]

Actually the price of electricity in Finland is among the lowest in Europe. This is one of the chief reasons how our system works. You see, we have a lot of traditionally extremely energy-intensive industry related to forestry (i.e. paper, carton and cellulose production), metalworks (both smelting and advanced machining such as shipbuilding) and so on. As a result, one of the primary goals of the entire country's energy policy is to ensure that electricity would be as cheap as possible. This kind of forward planning is what allows for those record profits. Not electricity prices, that are very cheap in Finland by European standards to the point that it was one of the chief reasons why most of the heavy industry stays in the country, and why modern energy intensive industries like heavy datacenters (i.e. Google) find Finland so interesting for their European operations.

The thing is: Cheap electricity prices make nuclear (and everything else) less economical. So the question still is why should nuclear plants be more profitable in Finland than elsewhere. Weren't the current plants not build by a government-owned power company (Imatran Voima Oy) which was then privatized later? Considering this, I assume that the existing nuclear plants in Finland were probably not really economical, but if nobody does an audit of how much this government-owned power company actually has spent when building these plants this will never become apparent. Looking at old press articles about how Loviisa started out has a hybrid of Sowijet and Western technology and needed costly repairs and changes, I somehow doubt that it was so economical as claimed.

Some other things you should understand before arguing on the topic of "eating profits".

....
Ok. But my point was that you should not sectively pick the successful projects while ignoring the cost of the failures when discussing the overall economics of nuclear. If the French tax payers pick up the bill for that disaster this is certainly good new for Fins, but does not really make nuclear more economical in the overall scheme of things.

Re:Brittle

[Luckyo]

1. Because even with cheap electricity prices, they are still very profitable. This is really not that hard to comprehend. Lower operating costs per unit of electricity produced = more profit.

2. Except that it's not "French tax payers" but "Areva". And Areva is in fact a multinational corporation, not a French government subsidiary even though approximately 90% of ownership is in French state's hands.
Their main problems right now are German decision to phase out nuclear power, reduction of nuclear design and building contracts due to Fukushima accident as well as Olkiluoto 3 problems. This has caused French government to increase capitalisation of the company.