Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Fukushima accident was preventable

rsta.royalsocietypublishing.org

Post reply on HN
Print view View original

21–30 of 112 posts

Re: The Fukushima accident was preventable

#21

Post by nickff »

PaulHoule wrote: post #15
nickff wrote: post #4

As I understand it, the Fukushima plant was never designed or rated to sustain such a large earthquake or tsunami. If this understanding is correct, we should not have expected it to survive the damage, and the problems were not with the design, but perhaps with the specification (depending on whether you think this should have been foreseen). It seems to be a common thread with all tragedies and disasters that peopl…

If you read closely you see that the accident was so bad because of one simple problem. If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. It doesn't take a huge amount of energy to do this, but it does take some. If the power goes out at the station and they can't get emergency power, the outcome…

I have read that many times, and it makes some sense. The issue with this line of reasoning is that the move would be a design change which is not required by the specification (as I have read and understood it), which would have been seen as unnecessary waste at the time.

A study which I would find more important and useful than the one here would be a cost/benefit analysis of increasing all specifications relating to all (similar) low probability events. In other words, if you had been a designer of the plant looking to spend an extra $500000 to make the plant safer, would you have spent it on moving the generators? How many other contingencies would have been higher priorities than this one (if any)? What would be the total cost/benefit of applying this heightened standard to all new facilities? Would this be statistical murder?

Re: The Fukushima accident was preventable

#22

Post by bsder »

Of course it was, as were things like the explosions afterward.

However, management always gets in the way--either up front, because there is profit pressure, or on the backend, because there is profit and/or political pressure. This paper covers the up front failures.

However, backend failures, like spraying water on the core (NOT one of the established procedures because calm engineers knew that the reactor could dissociate the hydrogen and oxygen) rather than letting the core melt into the bottom of the containment area which was designed to deactivate and contain the core, were also rampant.

This was just like Three Mile Island. If people had sat on their hands, done nothing, and let the engineered last-chance safety systems do their job, things would have turned out better.

Reactors should not be for-profit. Rickover showed us all how to do it right, but we lack the stomach.

Here is his quote about real reactors: "On the other hand, a practical reactor plant can be distinguished by the following characteristics: (1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated."

Re: The Fukushima accident was preventable

#23

Post by jfoutz »

bsder wrote: post #22

Of course it was, as were things like the explosions afterward. However, management always gets in the way--either up front, because there is profit pressure, or on the backend, because there is profit and/or political pressure. This paper covers the up front failures. However, backend failures, like spraying water on the core ( NOT one of the established procedures because calm engineers knew that the reactor could…

That almost sounds like a human interaction problem. Maybe a codebook with keys, that gives you access to a room with a big lever, that doesn't really do much other than kick in the emergency last chance safety systems a little early is the right way to go.

edit

And they should really hollywood it up. all the lights in the building dim, the siren from alien blaring, maybe a fog machine in the room with the lever.

Re: The Fukushima accident was preventable

#24

Post by ansible »

PaulHoule wrote: post #15
nickff wrote: post #4

As I understand it, the Fukushima plant was never designed or rated to sustain such a large earthquake or tsunami. If this understanding is correct, we should not have expected it to survive the damage, and the problems were not with the design, but perhaps with the specification (depending on whether you think this should have been foreseen). It seems to be a common thread with all tragedies and disasters that peopl…

If you read closely you see that the accident was so bad because of one simple problem. If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. It doesn't take a huge amount of energy to do this, but it does take some. If the power goes out at the station and they can't get emergency power, the outcome…

If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core.

This is the one simple problem.

There are now reactor designs that are passively fail-safe. So that even if all the pumps and everything stop, it will still not result in an explosion or otherwise serious release of radioactive material.

I don't know how much those sorts of designs were developed at the time Fukushima was commissioned though.

Re: The Fukushima accident was preventable

#25

Post by monochromatic »

bsder wrote: post #22

Of course it was, as were things like the explosions afterward. However, management always gets in the way--either up front, because there is profit pressure, or on the backend, because there is profit and/or political pressure. This paper covers the up front failures. However, backend failures, like spraying water on the core ( NOT one of the established procedures because calm engineers knew that the reactor could…

> Reactors should not be for-profit.

Maybe. The motivations are different for a government project, but I'm not convinced that they're better.

Re: The Fukushima accident was preventable

#26

Post by thescriptkiddie »

jonknee wrote: post #3

In hindsight all accidents are preventable.

Only under an overly broad definition of "preventable". In the context of this article, "preventable" means that the failure mode was foreseen and not accounted for in the design. If the failure mode had not been foreseen then the accident would not be preventable, because how can you protect against something you can't even imagine?

Re: The Fukushima accident was preventable

#27

Post by nickff »

ansible wrote: post #24
PaulHoule wrote: post #15

Earlier quoted context omitted.

If you read closely you see that the accident was so bad because of one simple problem. If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. It doesn't take a huge amount of energy to do this, but it does take some. If the power goes out at the station and they can't get emergency power, the outcome…

If a nuclear reactor has a cooling failure, the fuel will eventually heat up and then melt down. To prevent this you have to keep water circulating around the reactor core. This is the one simple problem. There are now reactor designs that are passively fail-safe. So that even if all the pumps and everything stop, it will still not result in an explosion or otherwise serious release of radioactive material. I don't k…

This all misses the point of my first post.

You could have a much safer design available, but if the 'less safe' design is more cost effective, and meets all specifications, it would still be the preferred design. This means that the any problem is with the specifications/requirements. The next question is whether the standard of safety which would require choosing the 'failsafe' (or at least failsafer) design would cause statistical murder.

Re: The Fukushima accident was preventable

#28

Post by dredmorbius »

bsder wrote: post #22

Of course it was, as were things like the explosions afterward. However, management always gets in the way--either up front, because there is profit pressure, or on the backend, because there is profit and/or political pressure. This paper covers the up front failures. However, backend failures, like spraying water on the core ( NOT one of the established procedures because calm engineers knew that the reactor could…

The point that it's organisational and management issues which so frequently seem to be behind major disasters -- four of the larger nuclear accidents (Fukushima, the earlier Japanese criticality incident at Tokaimura, Chernobyl, Three Mile Island), as well as numerous other large-scale industrial accidents, of which energy systems play a large role: the BP Gulf Oil spill, Exxon Valdez, Banqiao Dam (China, 1975), recent South Carolina flooding and dam bursts, the Union Carbide Bhopal, India, disaster.

You cannot engineer out human nature. This isn't a root cause for which there are technical solutions.

I hugely recommend Charles Perrow's Normal Accidents and The Next Catastrophe. As well as other writings.

Note that Rickover also wished we'd never gone to the nuclear option. He defended his choice for lack of options, but would have preferred to see all plants mothballed.

"Paper Reactors", which you quote in part, is excellent.

Re: The Fukushima accident was preventable

#29

Post by dredmorbius »

maxerickson wrote: post #20
ChuckMcM wrote: post #19

Earlier quoted context omitted.

I'm not sure if you agree that the findings are unsustainable or not. Two things that the IAEA had established were that 1) Fukishima survived the earthquake as designed, and was in the process of shutting down when the tsunami hit. 2) The tsunami disabled primary and backup power to the cooling systems which was the proximate cause of the failure. Further, at the time of its commissioning, the tsunami it experienced…

This report directly disagrees with Further, at the time of its commissioning, the tsunami it experienced was accepted by the best engineering data at the time to be impossible. Directly. This part uses scare quotes to describe the 'quality' of the work: Its initial application was based on the 3.122 m measurement local tsunami height (above Onahama Peil (O.P.) reference sea level), observed during the 1960 Great Chi…

British use of quotes is typically distinguished from American, in that where emphasis using language from the original document is intended, those words are typically quoted. You'll see this extensively in BBC headlines.

They're not "scare quotes", to quote you. They're direct quotations, for emphasis.

Re: The Fukushima accident was preventable

#30

Post by lucozade »

WalterBright wrote: post #12
Johnny555 wrote: post #7

Isn't every accident preventable in hindsight since you know exactly what the failure mode was? If they'd built the generators on a hillside that was washed away in a mudslide the article would read "Critical backup generators were built on unstable hillside despite warnings from scientists".

The idea with building safe systems is not to imagine what could cause subsystem X to fail, but to figure out how to cope when subsystem X fails. The most obvious design failure at Fukushima was not "how big a tsunami we should protect against" but not asking "how will we cope when the seawall fails". If the critical backup generators had been in a bunker designed to protect them from a seawall breach, the disaster w…

Although it's been a very long time since I did engineering that could actually kill people, this idea that you focus on what can go wrong and how you mitigate it has stuck with me and has proved useful in lots of things.

Having said that, the next questions are usually: what is the likelihood of it going wrong and what is the cost of mitigation? I don't envy the people making those decisions on something like a nuclear reactor, with or without hindsight.

Post reply on HN