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25th Anniversary Of Three Mile Island
fbform writes "March 28, 2004 is the 25th anniversary of the Loss Of Coolant Accident (LOCA) at the nuclear power plant on Three Mile Island, Pennsylvania. It's a good time to reflect on the impact it has had on our nuclear safety policy and interface design in general."
Oblinks to related wikipedia articles:
Three Mile Island
List of nuclear accidents
Fusion power is the way to go. It's potentially much safer and can generate a ton of electricity without air pollution.
Especially pebble bed reactors.
That would make things much worse in the event of a meltdown. The radioactivity has to go somewhere, and instead of being pelted into the air or lingering in and around the reactor it would wind up getting leached into the soil and causing massive contamination of any watercourses within a few kilometres, which would probably be even worse and slow down long-term dispersal of radioactive particles.
Groundwater. Contaminated groundwater, and LOTS of it.
Well, Chernobyl blew its 12 foot thick reinforced concrete lid far enough into the air to flip over. And all that heat has to go somewhere - you'd probably end up with a local volcano.
Then, when it all cools down, groundwater will get into it and spread radiation throughout the watershed. If it didn't boil of as radioactive steam first. Think of the problems if a reactor in the upper reaches of the Missouri explodes, and radioactive water contaminates the whole Mississippi-Missouri water system. Not fun.
Consciousness is an illusion caused by an excess of self consciousness.
Compare the Soviets worst accident- dozens dead in the short term, thousands dead early from long term effects- with the United States worst accident- Three Mile Island. The radioactivity release from TMI was projected to cause less than 1 premature death from the hundreds of thousands of people potentially exposed to anything, and in twenty five years since, no one has been able to prove that they were adversly affected by the accident, healthwise.
Including the people who work there.
Nuclear Power is perfectly safe when done right, and it's done right in the US. The worst that could happen in the US in an accident condition is that parts of the power plant are destroyed. And for even that to happen, so many very closely watched things would have to go wrong that it's basically not going to happen.
So shut off your lights if you don't like nuclear power, and go back to your cave.
Alcohol, Tobacco and Firearms should be the name of a store, not a government agency.
Chernobyl was a completely different animal to TMI. Operators at the plant brought that disaster entirely upon themselves. They were doing an "experiment" to see what the minimal resources were to keep the plant operating, overriding automatic shutoffs and other alarms in the process. Eventually, they overrode one alarm too many.
TMI was much more of a true accident. A valve malfunctioned to start the whole thing, something that didnt require a direct human action to occur.
The One Rule Of Chess You'll Ever Need: Don't play someone who carries a kit in their bookbag.
If they had used analog dials instead of digital readouts, the operators would have seen a bunch of dials all pegged high, instead of seeing what looked like an instrument failure.
Given that data, there's chance that when steam bubbles started forming in the primary system outside of the pressurizer (your "voids"), the operators would not have shut down the primary reactor coolant pumps (the big pumps that circulate water between the core and steam generators). The operators shut down those expensive pumps because the steam bubbles caused them to start cavitating, which would eventually destroy them. If those pumps had been kept running, the core would have received some cooling, and the operators would have known that more was wrong...
Maybe if the operators had known that core temps were going through the roof they would have acted totally differently.
PS - I have no idea how the operators could have missed a stuck-open relief valve - even a steam relief valve from the top of the pressurize. When those things lift, it sounds and feels like a train going by...
The statement "(t)he coolant doubles as the moderator" is also true of American light-water designs.
The Earth's core is all melted. You know why it's so hot? It's because of the enormous quantities of uranium within it that is undergoing radioactive decay. Yes, the Earth is a big radioisotope heater.
Mod down posts with a "Free Mac Mini/iPod" sig, they're spam!
Yeah, that would suck for all those people living under the earth's crust.
PS: Ca-48 half-life 6e+18 y abundance 0.1874%
People do not realize that:
1) 80% of electricity in France is nuclear (Paris vacation, anyone?)
2) There is more radiation in the U.S. Congress due to its granite construction than is permitted outside a nuclear plant
3) If you take 4 cross-country airplane trips, you get more radiation than allowed at nuclear plants
4) If you live in mountains (Colorado) you also get more radiation, due to the altitude
5) Best estimates are for 325 long term general population deaths arising out of the Chernobyl radiation escape. Guess how many cancers due to oil/coal burning plants elsewhere?
6) Current nuke plant designs have a bias for automatically stopping the reaction at the slightest or even gravest out of spec situation. Imagine your car's engine designed to stop every time you rev up/speed/your dome light burns out.
Fact is, greenies have scared the public, we are currently poisoning our air with oil/coal power plants, creating thousands of new cancers every year. Thanks, tree-huggers.
The next pasture is always greener
BNFL (British Nuclear Fuels Ltd) reprocess spent fuel rods to recover fissile material (and waste):
www.bnfl.com
Sorry about the lack of detail, but I couldn't find anything more specific on their site.
Many people are unaware that on January 3, 1961, SL-1, a small (about 3 MW) nuclear reactor was destroyed due to a "reactor explosion" at the National Reactor Testing Station in Idaho Falls, Idaho, killed one navy technician and two army technicians, and released radioactivity "largely confined" to the reactor building.
.01 seconds, causing the plate-type fuel to melt. The molten fuel interacted with the water in the vessel, producing an explosive formation of steam that caused the water above the core to rise with such force that when it hit the lid of the pressure vessel, the vessel itself rose 3 meters in the air before dropping back down.
One technician was blown to the ceiling of the containment dome and impaled on a control rod. His body remained there until it was taken down six days later. The men were so heavily exposed to radiation that their hands had to be buried separately with other radioactive waste, and their bodies were interred in lead coffins.
One of the victims was interred at Arlington National Cemetery:
SUBJECT: Internment of Radioactive Remains
TO: Superintendent
Arlington National Cemetery
Arlington 11, Virginia
1. Radioactive remains of SP4 Richard L. McKinley were interred at Arlington National Cemetery on 25 January 1961.
2. It is desired that the following remark be placed on the permanent record, DA Form 2122, Record ofInternment:
"Victim of nuclear accident. Body is contaminated with long-life radio-active isotopes. Under no circumstances will the body be moved from this location without prior approval of the Atomic Energy Commission in consultation with this headquarters."
A careful examination of the remains of the core and the vessel concluded that the control rod was manually withdrawn by about 50 centimeters (40 centimeters would have been enough to make the reactor critical), largely increasing the reactivity. The resulting power surge caused the reactor power to reach 20,000MW in about
TMI wasn't the first or only nuclear reactor accident in the US.
In spite of this 'negative publicity', I still strongly support nuclear power.
You can find the E2 writeups here.
(not the same anonymous user)
Thousands of pieces of gear were individually checked, tested, or analyzed via engineering computations. The NRC required a report to be delivered for each plant with all these qualifications individually listed. IIRC, the reports we generated were over 5 inches thick.
Never heard what happened after that...
Not quite true...SL-1 (the army's abortive attempt at developing a mobile reactor) killed 3 or 4 people when it become prompt-critical and exploded from a rapid increase in pressure due to the formation of steam in the coolant channels inside the pressure vessel. The power excursion was something on the order of 10,000 times the rated power. I saw another post on SL-1 somewhere in here, it had much more specific information.
Si hoc legere scis nimium eruditionis hebes
The parent is correct.. if worded badly.
TMI was a case of automatic safety systems being overrided by undertrained human operators. As the story paragraph mentioned, TMI was a stark lesson in control systems design.
In the control room the operators had no feedback about how much water was in the reactor core, just one gauge showing the level of water in the pressurizer tank near the top of the system. When a valve near the top of the pressurizer stuck open (referred to as the PORV or pressure operated relief value) the steam that normally kept the water near the bottom of the pressuizer tank started leaking out. More water flashes to steam.... and TMI is now losing water. The operators saw the opposite, the water level was rising on the level gauge for the pressurizer and they started reducing and eventually draining water out of the system thinking some malfunction was causing water to be introduced. None of the operators was able to step back from the initial theory that water levels were rising, despite large amounts of contradicting information. (Hours into the incident an off-duty operator arrived and with a fresh set of eyes figured out what was happening)
There are a lot more things that went wrong that night... (the initial shutdown was caused by water accidentially getting into the compressed air supply for the pneumatic control systems in the steam room, a valve closed at the wrong time and burst one of the steam lines to the power turbines)
TMI is a fascinating example of how multiple redundant systems still can fail, given a long string of "coincidences" One can argue that failures of this type are like winning the lotto, their is little chance of it happening on on particular day, but given enough days it is certain to happen to someone. Hence the need for "fail safe" designs.
You said: "The truth is that the better designs of forty years ago could have made safe nuclear power. The CANDU heavy water system is genuinely fail-safe. The coolant doubles as the moderator. That means if you loose one you loose the other and the reaction is halted."
This shows the naivety of some people who are not nuclear scientists or reactor operators regrarding nuclear power. Let me give you a quick lesson.
A reactor can be in several operational states: shutdown, starting up, at power, or shutting down. During startup the reactor will in a state known as supercritical. This means that for every neutron that causes fission in a uranium atom, more than 1 will cause fission in others. This allows reactor power to increase. Once desired power is attained the reactor will again be made critical (where there is a 1 to 1 ratio). When you want to shut down the reactor you make it subcritical. All of this can be controlled by control rods (among other things).
Chernobyl blew up because they had an accident that made the reactor very very supercritical. Power increased until the core exploded, shutting it down.
Now here's the shocker: TMI-2 was shut down when it partially melted down. Control rods were fully inserted. This means that the fission reactons for the most part had stopped (though they would still be occuring at trillionths the rate that they occured while critical). So fission was not generating any heat.
So what partially melted and reorganized the core? Decay heat. When fission occurs fission fragments are the result. These fragments fall away from the line of stability, hence rapidly beta- decay. Obviously this is governed by thier half-lives and the resulting fission products from any fission are pretty much random (though there are statistical proportions). This means some products will have short half-lives, others long, etc. And most products will probably go through many beta and perhaps alpha decays before reaching a stable point. This means that decay heat will be greatest right after shutdown, but will decrease over time.
This is why TMI-2 partially melted down. The reactor was critical, it was shut down, but the decay heat wasn't removed, so the reactor melted. It could happen to CANDU just as easily if they lost the ability to remove decay heat (which is why loss of coolant or loss of pressure control casualities in nuclear plants are big casualities).
You said: "Today there are vastly better designs, like the pebble bed reactor that MIT and others have been looking at."
There is no design that magics away decay heat. Sorry.
Suddenly, the hairy finger of a familiar monkey tapped me on the shoulder. It was time.--G. T.
As an ex-nuclear machinist's mate aboard a US Navy sub I can tell you for a fact that the record is perfect. The 2 subs lost (Thresher & Scorpian) were not due to nuclear accidents. The original design and construction of the USS Enterprise included 9 reactors (9? whew!) in which 7 were subsequently removed. Each could power a city of about 250,000 people effectively. And by the way, most nuclear power plants ARE run by ex-Navy personnel. Most of them hire no one but ex-Navy.
[SIG] Remember Mattel handheld games?
CANDU is also a breeder reactor that creates material that can be used in bombs, and was used as such by India and North Korea.
For years now, the folks guarding nuclear plants have been armed to the teeth.
They have no-fly zones around nuclear plants now. Not really because flying inside the line gets you shot down, but so they can aim a SAM at an incoming threat without worrying about hitting the wrong plane (not that they're worried about hitting the wrong plane - it's really that they're worried about missing the right one).
So let's pretend we're mad as hell and not going to take it any more. What's the plan?
9/11 style air attack won't work. You'll either get SAMed or the containment building will likely survive the impact.
Armed assault will be met with armed resistance. The minute the attack starts, someone presses the panic button and the cavalry arrives.
No, the only credible terrorist threat in my mind is an inside job - someone gets a job as a plant worker and sabotages the plant. If the plant were a fail-safe design, however (as a previous posted pointed out, current plants are designed with redundant systems, but are not fail-safe), the worst the criminal could do is shut the plant down and perhaps try and disperse the fuel with explosives (note that due to a failsafe system, he won't get any help dispersing the fuel from the plant itself). His ability to smuggle explosives into the plant without being detected will limit the effectiveness of that plan. Never mind that he'd have to be able to breach the containment building (yes, even a fail-safe reactor will likely have one).
Sabotage is certainly a threat at current nuclear facilities, just as it is a threat at, for example, petrolium refineries (I'd actually put Richmond, CA ahead of, say, San Onofre on a threat list). Better design mitigates that risk, just as it mitigates so many other risks.
After rocky flats, the detroit reactor neer explosion, hanfords non stop spew of radiation and of course after the nation had been glowing with nuke test fallout for 30 years, THEN they decide to wimp out because a reactors failsafes actually began working to the point where there was little radiation leakage ? WTF ?
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The russians on the other hand, their main food production area is not EPA weenie HOT, its will I die of this THIS year hot. And they keep all the reactors of the same type going because if they shut them down they'll FREEZE to death.
In the US most of our energy problems are self inflicted, political scams to run up energy sales prices, the oil companies sticking it to the consumer every time the EPA sticks it to them, calfornia sucking up all the cheap natural gas so they can have "clean" power and then the people in the northern states who relied on that for home heating now have their bills tripple or more. While those using heating oil and some cases even just electricity are now paying less while carbon fouling the air like crazy. And don't think that coal is "non-nuclear" the ash from burning that doesn't go up in the air is contains enough uranium and thorium to be a potential source of reactor fuel. http://www.ornl.gov/info/ornlreview/rev26-34/text
At least in a nuclear plant they keep the waste and fuel contained, not blasted out of a smoke stack or floating around on some barge until they can find a country to unload it in.
The energy has to come from some place. And it HAS to come from YOUR BACK YARD because the grid wasn't made to have power generated in a designated dirty state like kentucy, or tennessee and transmitted all the way to the east coast. The question is, do you want CO2 and thorium ash spewing plant in every city, or a reactor powering 12 cities and giving some neurotic mommies a panic attack 6 times a day.
As for alternate energy, solar cells take a lot of power to make, windmills take energy to machine and transport to the location, micro-turbines/water wheels require a certain type of landscape and water supply. All these are great if you live in the middle of nowhere. Solar heating/cooling is great if you can afford to have it worked into your house.
But the bulk of your power needs still come from coal and nuclear power. And nuclear power can't continue if you have to bury every ton of concrete ever touched by 12 extra neutrons in some dump. And coal burning can't go on for another hundred years or we'll run out of air. This means we have to come up with some sort of reasonable nuclear regulation, acceptable loses, etc.
Sorry 'bout that all-caps, but this is important. The exhaust of a gas drier is not only carying the evaporated water from the drying clothes, it is also carrrying the combustion exhaust from the gas heater. You DO NOT want to be running those combustion gasses to the interior of your home, where people would like to remain alive.
The core is not entirely liquid. Geophysicists have determined using seismic readings (since certain waves will not travel through liquids but will travel through solids) that the inner core is solid and the outer core is liquid. This is because as the pressure in the earth increases as depth increases, the melting point decreases.
The core is not the only place that spontaneous fission is occuring. It is occuring throughout the mantle. This is the main reason that the average temperature of the earth is 800 C. The reason the core is the hottest is because the only real heat sink that the earth has is the crust (so logically temperature will decrease from the core outward). Obviously this incredible amount of stored heat does many things, including plate tectonics, vulcanism, and in the case of the outer core with its moving currents--the earth's magnetic field which operates your compass to point to the earth's magnetic south pole (which coincidentally is near the north pole, but hasn't always been there).
Look -for example - at the Sellafield plant in West Britain. It has a ludicrously, disgracefully bad safety record. As a reprocessing plant also, Sellafield is slowly poisoning the Irish sea. Nuclear waste is buried beneath the waves in containers which are - allegedly - likely to rupture within 50 years of storage. It'll be a HELL of a lot longer before the waste stops polluting the sea and killing the fish and plants in the vicinity. Nuclear power could be a very viable source of power if there was any viable long term solution for storage of waste products. When one takes in security there are currently NO viable methods for disposing of nuclear waste.
And by the way, to all the rednecks who pronounce it "nucular", learn to enunciate!!!
Bzzzzzt..."AAAAaaaaarrrgh!!!" Thud.
Austrailia must not have HOAs (Home Owners Associations) similar to those in the U.S.?
It took ages for my friend from Arizona to explain HOAs to me. At first I thought he was talking about a kind of a vigilante action group. Here we just have a local council of elected officials that make up housing regulations.
They generally let people access the sun using ropes for the purpose of drying their washing.
No, that's simply not true.
Union Carbide in Bhopal: 3000 to 8000 dead; over 100000 injured.
Chisso Corporation at Minimata: mercury poisoning kills hundreds, with at least 3000 people afflicted.
The Grandcamp in Texas: Fertilizer explosion kills nearly 600; over 3500 injured.
Chernobyl: fewer than 100 deaths to date; fewer than 1500 known attributable radiation-related illnesses. Potential premature deaths due to excess radiation exposure estimated to be 3000, but we'll have to wait and see.
Nuclear power is dangerous, but there's a lot worse out there. Look up deaths attributable to coal-fired power plants sometime.
So, because there's less energy per gram, CANDU system have online fueling, which means that the reactor is fueled/refueled while it's still producing power. This actually happens (ideally) everyday. A LWR runs for ~18 months, then shuts down as it gets defueled/refueled.
Contrary to popular belief, CANDU isn't any more "safer" due to this design. If you're purely talking from a physics point of view, CANDU does look safer because of the lower amount of fission that goes on (thus less heat), and the design is pretty good. BUT.. you run into problems when you're constantly opening up channels on on-power, due to wear and tear on machinery (high-doses of radiation isn't great for most metals, eletronics, etc) and the possibility that you might get fuel in air (even though it's spent) exists.
So, nothing is failproof (duh!), even with the newer designs. But what you can do is limit the likelihood of something bad happening, and be prepared for it if and when it does (defense in depth), and limit the damage.
That being said, I think the nuclear industry does have problems, but there have been some MASSIVE improvements over the last 15 years. No civilian has yet to die due to a nuclear accident in north america which is pretty amazing looking at any other industry out there (dams kill a surprising # of people every year). But you have be vigilant... it only takes seconds to mess things up all over agin.
>But the consequences of nuclear power station failure are more severe than any other category of civilian accident.
Dam failure in China, 80,000 dead.
You don't even want to think about worst-case failures of LNG tankers.
you make a fine case for going with renewable energy sources like wind turbines, solar power, wave energy and the like. I can only suppport that.
However, you got one thing wrong with fossil fuels. They don't contain radioactive carbon-14 (C-14). C-14 is steadily produced in the the upper parts of the athmosphere by cosmic radiation bombarding nitrogen atoms. C-14 has a half life of ~5730 years, and any C-14 in the original organic material that formed oil and coal millions of years ago is long gone. That's how you make C-14 dating. The less C-14 in a sample, the older it is.
Not to pick but as a former MM on the Enterprise she was originally designed, and currently contains 8 reactors. All Nimitz class carriers contain 2 reactors.
You are correct that each reactor could power a small city. The prototype I attended in Idaho at the INEL (now INEEL) actually supplied power from the A1W and S1W reactors to a small local city. The power companies did not like this and had congress stop this in the 60s.
Additionally, as of this posting, no one has mentioned that the Navy's reactors contain highly enriched reactors. It would be cost prohibitive for civilian reactors to enrich their fuel to the levels of the USN.
BTW I am posting anonymously due to mod points that I have all ready doled out on this thread. I post as Yazheirx
Yeah, yeah, I have a doctorate from Oxford Univ. Nuclear Physics Lab. Where is yours from? I have also worked as a control engineer.
From your tone you sound like an ex-nuclear power employee who just has to spend their time writing self-justifications on the Internet. Sorry, you have no more credibility with me than the rentacops who used to do airport security here in Boston before 9/11. You guys screwed up real bad, you lost the public trust, that is because you deserved to.
You might be correct in claiming that it would be possible to design a safe PWR. I don't care, if anything that looks like a PWR is built it will be run and staffed by the same discredited establishment that gave us Three Mile Island and Chernobyl.
I think the public has it wrong, nuclear power deserves a second chance. But no, the nuclear power industry does not.
Looking for an Information Security student project suggestion?
Try http://dotcrimeManifesto.com/
Deuterium (D-D) based fusion is just approaching its break even point, IF some as yet unconfirmed results in sonogram induced fusion at ORNL (Oak RIdge National Labs), Lawrence-Livermore, and other locales check out.
The "apparently benign gas" you are referring to is radioactive helium. It's benign in that 1. We're talking about radiation levels of 1/1,000th or so of the more serious fission byproducts. 2. Helium is chemically inert, so living things can't incorporate it into their tissues and it can't be concentrated up the food chain. 3. Helium leaks don't lay around on the ground where people can walk through them, pick some up on their shoes, etc.
Who is John Cabal?
I wouldn't say exactly perfect, unless you don't have a problem with dumping out radioactive waste.
There's 7 incidents we know about. Given the secrecy of the military who knows if there's more that we don't.
from: http://en.wikipedia.org/wiki/Nuclear_disaster
1954 - The submarine USS Seawolf (SSN-575) scuttles an experimental sodium-cooled reactor in 9,000 ft (2,700 m) of water off the Delaware/Maryland coast. At 33 kCi it's likely the most radioactive single object ever deliberately sunk, and has not been retrieved as of 2003. The reactor had problems with corrosion from the coolant, and was replaced by a conventional light-water reactor.
October 1959 - One killed and 3 seriously burned in explosion and fire of prototype reactor for the USS Triton (SSRN/SSN-586) at the United States Navy's training center in West Milton, New York. The Navy stated "The explosion was completely unrelated to the reactor or any of its principal auxiliary systems," but sources familiar with the operation claim that the high-pressure air flask that exploded was to feed a crucial reactor-problem backup system.
1961 - The USS Theodore Roosevelt (SSBN-600) attempts to dump the depleted resin from its demineralization system (used to remove dissolved radioactive minerals and particles from the primary coolant loops of submarines). The ship is contaminated when wind blows resin back onto the ship.
December 12, 1971 - In the Thames River near New London, Connecticut, radioactive coolant water is being transferred from the submarine USS Dace (SSN-607) to the submarine tender USS Fulton when five hundred gallons are spilled into the river.
1975 - The USS Guardfish attempts to dump the depleted resin from its demineralization system (used to remove dissolved radioactive minerals and particles from the primary coolant loops of submarines). The ship is contaminated when the wind blows resin back onto the ship. This type of accident is fairly common (see 1961).
October-November 1975 - While disabled, the submarine tender USS Proteus discharges radioactive coolant water into Apra Harbor, Guam. A Geiger counter at two of the harbor's public beaches showed 100 millirems/hour, fifty times the allowable dose.
May 22, 1978 - Aboard the USS Puffer near Puget Sound, Washington, a valve was mistakenly opened, releasing up to 500 gallons of radioactive water.
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