Twenty to thirty years ago a power plant failure or serious problem could lead to fallout spreading for hundreds of mile like it did in Chernobyl and almost did at three mile island. I assume there are close to a five hundred nuclear plants on earth and so far only two meltdowns have occured, are the newer ones being built built so that the problems of three mile Island or Chernobyl are near impossible or has nuclear safety technology not changed much? From what I know of those two meltdowns, they occured because a series of mistakes was made back to back, would the new generation be able to avoid even the problems due to a series of mistakes that lead to too much pressure building up?
For starters, TMI was a “partial meltdown” with very small release of radioactive material. More of a “Gee it’s getting hot in here.” Chernobyl was a catastrophic meltdown with significant release.
The US Nuclear Regulatory Commission says that safety at US plants has been improved as a result of lessons learned at TMI.
It is believed that a Chernobyl-type accident will not happen at US plants, primarily because the design of the core is completely different. There’s nothing inherently wrong with the Russian RMBK cores, but they are less “forgiving” of operational errors and overall, less robust.
Forgot to add - There are currently 140 reactors in the US - 104 commercial power plants and 36 research reactors, mostly at universities.
Globally, there are 439 operatinng reactors - unfortunately, this isn’t described as all types, or just commercial power.
I know, but from what I remember Three mile island could’ve spread nuclear material for hundreds of miles had they not gotten it under control.
As a high school student, I researched the Chernobyl accident and the best source I found (in an admittedly small library) stated that:
- The Chernobyl accident was an escalating mess of endless jumbles over a period of 24[sup]1[/sup] hours
- that could still have been prevented up until 30 seconds before actual meltdown
The problem[sup]2[/sup] with Chernobyl wasn’t one of insufficient security measures (since until quite late in the game, you can still just say the heck with it and turn the sucker off) but simply the influence of Russian Communism on the workers there with no one being willing to stand up and say “Heck with it” and just turn the sucker off.
[sup]1[/sup] It wasn’t necessarily 24 hours, but I do recall that it was a very lengthy period of time.
[sup]2[/sup] According to my recollection of the one book.
Well, anything could happen if the operators don’t get it under control. But there wasn’t a meltdown at TMI and one wasn’t likely to have occurred under any scenario outside an action movie.
Chernobyl and the entire old USSR nuclear power program were so different from plants anywhere else in the world as to not be talked about in the same topic. They built those plants without containment. Nobody else did it then, and obviously nobody would do so now.
So asking if things are safer now is misleading. Chernobyl is in no way representative. The technical answer is that, yes, every single year they add new safety devices, protocols, and procedures to nuclear plants, so they are theoretically safer every year. Small leaks have occurred in various places - there was just one in Japan, IIRC. But if you’re looking for meltdown comparisons in the western world, the real answer is that nuclear plants are as safe today as they were then because they weren’t really unsafe then.
Yeah, I saw a history channel documentary on Chernobyl where there was a really, really incompetent manager who was brought in to run an experiment and who threatened all the underlings why tried to put a stop to his dangerous experiments by pointing out how dangerous it was.
I think you will find that power structures incompatible with good safety management are a common feature of most organisations. Indeed, I’ve heard it suggested that American Capitalism has occasionally suffered from them. Allegedly.
The early nuke plants were essentially prototypes. It’s really hard to get something close to optimal on the first cut.
I got a tour by the chief engineer at the Ringhals (Sweden) power station. This comprises 4 reactors (3 PWR, 1 BWR) totatling about 3.8GW electrical capacity. This was not the show for tourists. It was a “heres a hard-hat, ear protectors, dosimeter…and don’t touch nothing” kind of tour.
One fact that really amazed me is that I was told (by the guy who’s buisness it was to know) that the cost of fuel amounts to around 2% (no, that is not a typo…TWO) of thier cost of production. The biggest cost was capital equipment, thus they operated to maximise lifetime of the reactors, which meant lower core (and more importantly steam generator) temperatures, and well below peak design neutron flux…thus providing additional safety margins. This reduced fuel effiency somewhat, but even if they were able to be twice as fuel efficient (impossible) it would have decreased thier cost of generation by only 1% and actually raised the long-term cost due to increased stress/wear on the steam generators (A heat exchanger in a BWR, apparently the first thing that wears out)
Though these are fairly dated, they were built around the time of the LAST of the US plants.They were purchased, effectivly, as stock catalog items from GE and Westinghouse. Pretty much every detail of the design and fabrication had been through several iterations of improvements. They were adding on a few improvements to the generation side, (like ceramic ball injection/capture to clean the condensors in service) but the reactor, controls, etc was considered a mature system.
This station was running for decades (still is AFAIK) with near zero unplanned downtime. MUCH more reliable than typical coal or gas fired plants. The steam generators had reached thier rated service life, so Ringals was pioneering the replacement procedure.
I’m pretty sure the station was run by the Swedish government. But it was real obvious that ALL the workers were extreamly conciencious and took pride in thier work. It must be a cultural thing…I don’t know any US govenment workers that exude that attitude.
Anyway, my impression was that here was a really mature, really safe operation. I’ve discussed this with some others, and our concensus is that maybe this would not work in the US, where private companys run the plant. At Ringhals, the chief engineer was the one making the decisions on how the station would be operated. With a private company running it, there will be some bean counter trying to make his quarterly numbers, and that doesn’t work. I’ve seen our DOE at work, and they ain’t going to get it done either. The other problem in the US is that cheap Pu fuel is part of what enabled thier operating philosphy.
Maybe it can work though. The hydoelectric dams seem to run pretty well.
I never saw a French plant. They seem to be doing it pretty successfully…and while I generalize, Frenchman and Swedes seem to be pretty far apart culturally.
Eh, if you’d rather he said “Russian communist dictatorship” instead, feel free. Under capitalism your boss can threaten to fire you, under actually existing communism he could threaten to send you to the gulags.
U.S. government workers - who would probably dispute your characterization - don’t run nuclear power plants in the U.S. They’re all civilian unless there are some serving military needs.
And the workers in U.S. nuclear plants have a culture of almost fanatic meticulousness in their work, partly as a way of combating the negative images of nuclear power.
Lemur866, say anything negative you want about Communism and I’ll probably agree, but in recent years there have been several thousand examples of Americans not standing up to their bosses, both in the corporate world, and rather notoriously in the political world.
regardless, modern designs have several nifty tricks to make a meltdown not only ridiculously unlikely, but physically impossible under any conceivable scenario.
My work involves ship casualties. I’ve seen a junior officer at the helm of a small naval vessel at night turn directly into the side of a bulk carrier (which he was pretty sure was there) at 25 knots because a senior officer (who’d just come onto the bridge and didn’t have night vision) ordered him to. I’ve seen a 3rd officer on a container vessel say nothing even though she was pretty certain that the pilot had just ordered a hard starboard turn into a sandbank. In both cases the person in question would have suffered no major sanction at all if they’d queried the position.
Forget communism, forget capitalism. Try “human nature”.
And if a modern ship’s systems which supposedly make an operational oil spill “not only ridiculously unlikely, but physically impossible under any conceivable scenario” actually made operational oil spills ridiculously unlikely (let alone impossible) I’d be out of a job.
If I recall correctly, at Chernobyl they were trying to find out if the last spins of the turbines, as the reactor is shut down, could power the water pumps that cool the reactor for the time it would take for the emergency generators to take over. They had to disable many safeties to perform the experiment and it didn’t go too well, obviously.
If you’re talking only about nuclear power plants, and only in the U.S., it’s hard to say. They’ve learned a lot from accidents and experience, and they all have containment domes. The newer (relatively speaking) plants are also better designed. However, no new reactors have been built for decades and the current ones are getting old. So in that respect, the reactors are getting more dangerous, even if only slightly. Some areas have a shortage of electrical generation capacity, so nuclear reactors might get pushed beyond their original retirement dates, with NRC approval I would guess. If a company wants to run an old power plant until something major breaks, it’s usually not a big deal, but it is when it’s a nuclear plant. When the plants get to a certain age, we don’t know what might happen. Failures may occur in unexpected places.
They found a large crack at the Davis-Besse plant that nearly penetrated the nuclear vessel, which contains the highly pressurized and radioactive coolant water. It was caused by boric acid. Had it not been discovered in time, it may have caused a serious accident. There was also a less serious problem at South Texas Project. I know we are talking about the U.S., but there were four deaths in a 2004 Japanese accident (no radiation leakage, killed by steam), so it’s not just the Soviet Union that has had accidents. Although it was an experimental reactor and is very different from today’s commercial reactors, three people were killed by an explosion at the SL-1 reactor in Idaho in 1961. Like Chernobyl, that type of accident cannot happen at current U.S. plants.
If you’re talking about all power plant, nuclear and non-nuclear, I would say that it has gotten much safer, especially in plant construction.
Basically the problem with Chernobyl was its design. Chernobyl 4 used graphite as the moderator (used to slow down the neutrons so that they can trigger the chain reaction). The problem with graphite as a moderator is that a loss of cooling will increase the power output. This can go so far as to cause a meltdown/explosion. At Chernobyl the fuel rods ruptured, and the resultant steam actually lifted the roof of the reactor containment. The air that rushed in actually caused the graphite to catch fire, and a second even stronger explosion followed.
In western reactor design, water is used as a coolant AND as the moderator. this means that a loss of coolant will actually cause the power to go down, because the neutrons are no longer slowed down, and the chain reaction is stopped. This means that the design inherently prevents a meltdown/explosion.