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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.
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.
there are 3 kinds of people:
* those who can count
* those who can't
https://en.wikipedia.org/wiki/...
Right...
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...
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.
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.
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.
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.
Maw! Fire up the karma burner!
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.
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."
[Fuck Beta]
o0t!
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.
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.
'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.
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.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
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.