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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
It's a shame that incidents such as this have contributed to the overall bad image of nuclear power. There is still a lot of potential which will probably never be revealed because the public at large are scared of what could happen if something went wrong.
The truth is that modern techniques could probably make nuclear power an extremely safe alternative.
Free iPods - now in the UK!
...is seeing how the fuck these accidents actually happen. Both Chernobyl and TMI seem to be based on a ridiculous chain of events fuelled by unfortunate coincidence, fallible mensuration equipment and human idiocy.
For instance, at TMI, there was a massive chain of events going like this (I'm taking this from the Wikipedia article). If any of these steps were omitted an accident never would've happened:
1. "The plant's main feedwater pumps in the secondary non-nuclear cooling system failed at about 4:00 a.m. on March 28, 1979"
2. "This failure was due to either a mechanical or electrical failure and prevented the steam generators from removing heat."
3. "First the turbine, then the nuclear reactor automatically shut down. Immediately, the pressure in the primary system (the nuclear portion of the plant) began to increase."
4. "to prevent that pressure from becoming excessive, the pressurizer relief valve (a valve located at the top of the pressurizer) opened."
5. "The valve should have closed when the pressure decreased by a certain amount, but it did not. Signals available to the operator failed to show that the valve was still open. As a result, the stuck-open valve caused the pressure to continue to decrease in the system."
6. "Meanwhile, another problem appeared elsewhere in the plant. The emergency feedwater system (backup to main feedwater) was tested 42 hours prior to the accident. As part of the test, a valve is closed and then reopened at the end of the test. But this time, through either an administrative or human error, the valve was not reopened -- preventing the emergency feedwater system from functioning."
7. "As the system pressure in the primary system continued to decrease, voids (areas where no water is present) began to form in portions of the system other than the pressurizer."
8. "Because of these voids, the water in the system was redistributed and the pressurizer became full of water."
9. "The level indicator, which tells the operator the amount of coolant capable of heat removal, incorrectly indicated the system was full of water."
10. "Thus, the operator stopped adding water. He was unaware that, because of the stuck valve, the indicator could, and in this instance did, provide false readings."
And so on and so forth. This is terrific shit. Seeing how many stages the thing went through just makes me glad this happened somewhere other than the decomposing USSR. With better engineering of measurement tools the whole thing would never have happened.
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.
How DARE you suggest that we pollute the pristine magma of the earths core with your unnatural nuclear waste. It would be a crime against nature to bury radioactve material under the earths crust.
People like you make me sick.
All Troll + "offtopic" mods are meta moderated as "Unfair", because you abused the system.
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
Reminds me of a quote by Terry Pratchett:
I once absend-mindedly ordered Three Mile Island dressing in a restaurant and, with great presence of mind, they brought Thousand Island Dressing and a bottle of chili sauce.
With the posting of the Chernobyl story yesterday, this should make some of us pause and think about what could have been...
Very true. It allows us to realize how fortunate it is that our engineers rejected the open-pile design which caused Chernobyl to be so dangerous. It also makes me thankful that, due to the skillful design, the TMI incident is a disaster only in the terms of public-relations among those who don't understand, or want to understand the science.
I don't think that anyone who isn't rabidly anti-nuclear power would consider these to events to be anywhere near equivalent. It says a lot for the systems that, despite the chain of human and mechanical failures, the incident at TMI was limited to such a small environmental impact. That wasn't by luck, it was by design decisions, choosing a much safer way to use nuclear energy to create power.
Bringing Chernobyl into the context of TMI shows that the person doing so either doesn't understand the science, or is trying to use fear of Chernobyl to convince others who don't understand the differences.
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.
No, it [nuclear power] is not safe
.
Nothing is completely safe. Thing is, the alternatives - the real, viable alternatives -- to nuclear power are even less safe.
You may recall the recent FDA advisory warning pregnant women and children to limit their intake of several types of fish because of mercury contamination in those fish.
The FDA guidelines call for children and pregnant women -- and women who "may become pregnant" to abstain completely from shark, swordfish, king mackerel, or tilefish, and to limit intake to six onces of albacore tuna a week.
What you might not have heard is that the panel that made the recommendation contained two members who were former lobbyists for the fishing industry -- or that another member, a scientist, not a lobbyist, resigned in protest because he believes that even six onces a week of albacore tuna is dangerous, and that that recommendation was only made because of industry lobbying.
What you also might not have heard is that the primary source of mercury in fish is from "mercury rain" -- and the primary source of mercury rain is from coal fired power plants
As it happens, the EPA is retreating from plans to more closely regulate mercury pollution from power plants, and "just coincidently" some of the language justifying that retreat is word-for-word the same as language in utility company memos.
So on the one hand, the fishing industry influences the FDA to soft-pedal its warnings to children and pregnant women, and on the other hand the power industry gets the EPA to continue to allow pollution.
And this is not to mention the other dangers of coal: despoiling the environment by digging it up, despoiling the air with smog when it's burnt, giving miners black-lung, etc.
I grew up a few miles from Three Mile Island, and I was still there when the accident happened, and I'll take clean nuclear power any day. Even in the worst case, we can contain a nuclear plant accident -- but we can't contain an ocean of mercury contaminated fish.
Opinions on the Twiddler2 hand-held keyboard?
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.