[updated below]
The answer apparently is that the techniques used to design for risk are just completely broken; and do not account for the fact that a single event can cause multiple problems; they assumed independence of risks that were in fact highly correlated. This is amazing to me, but oddly the exact same mistake seems to have been made by financial risk modelers.
I don't know why I'm surprised at this kind of stunning mistake. I guess at some level you assume that people capable of constructing and running a nuclear plant would also be capable of basic probabilistic reasoning; but; but it is never safe to assume competence, especially in the face of economic pressures.
[update: hm, here's a very detailed post by someone who sounds like he knows what he's talking about that says that basically things worked according to plan; despite some failures of some stages of containment and some safety procedures, there was enough backup to ensure that minimal radiation was released. OK.]
7 comments:
Hmm. He sounds like he knows what he is talking about, but he has absolutely no relevant experience or publications. I could have sounded as convincing after half an hour reading the Wikipedia. (And I have an MIT PhD, so obviously I know all about nukes.)
I've been carrying KIO3 tablets around with me for a decade, and am using this as an excuse to finally open the bottle.
Well, in my defense I did say "sounds like" for a reason.
Actually I also have to take back my remark about Japan as being comptent and not corrupt. Their institutions have plenty of incompetence and corruption, despite a lingering reputation for efficiency.
Getting the truth about what's going on over there is just about impossible. Pass the iodine.
Yes, the situation is totally under control, three reactors have melted down, there has been no significant radiation release, the US has moved its ships (which were 100 miles away) to a more distant location, numbers of people varying from 7 to a few thousand have been exposed to dangerous levels of radioactivity, there's no danger of radiation exposure, and France has told all its nationals to leave the whole of Japan.
Taking iodine is excessively paranoid, but I've been feeling silly for carrying the stuff around, and now I feel vaguely vindicated!
Your IEEE link is broken. It has excess end-quotes.
I predict that no deaths in the coming decade will be attributable to radiation resulting from the disaster. There was apparently somebody killed by a crane at one of the plants though.
I predict that no deaths in the coming decade will be attributable to radiation resulting from the disaster.
That's ridiculous. The people working at the plants have probably already absorbed enough radiation to cause them serious problems and some statistically certain deaths. But as to how wide an area will be contaminated and to what level, nobody seems to know much. Here's some more expert commentary.
Everybody's sold out of iodide here in CA and online, my wife is trying to get her sister on the East Coast to score some.
You write: "...you assume that people capable of constructing and running a nuclear plant would also be capable of basic probabilistic reasoning; but it is never safe to assume competence..."
I found it hard to believe that the Japanese did not consider the probability of earthquakes, considering that Japan is known to be earthquake-prone. It seemed to me more likely that their 'probabilistic reasoning' planned for a quake of lesser magnitude than the one that happened, which at 9.0 was a very severe and very rare occurrence.
Today, L. Gordon Crovitz confirms this in his "Information Age" column in the Wall Street Journal. Apparently the last earthquake of comparable severity to the one that just took place happened in the year 869. Crovitz writes:
"Its location on the so-called Pacific Ring of Fire has long made Japan one of the most earthquake-prone places on earth, but even so, no one thought to build its nuclear power plants to the specifications based on the accounts of monks more than a millennium ago.
"The plants were therefore built to withstand quakes of a magnitude 8.2, not the 9.0 that struck earlier this month, The difference sounds small, but given the logarithmic scale, this represents a 15-fold increase in force. The Japanese pride themselves on their engineering expertise, and despite the horrific scenes and leaked radiation, the engineering seems to have been fine. The plants would have withstood expected earthquakes and tsunamis. It was the assumptions about the risks of what might happen that turned out to have been faulty."
I am reminded of the experience of an old family friend, now long deceased, who back in the 1950s bought some undeveloped land along a riverbank, and thought it would be a nice place to build a house. He knew that the area was prone to flooding, so he consulted with a professor at the state university who was supposed to be an expert on the local topography. The prof examined the local records and plat maps, and assured him that the site he had chosen was above the 100-year flood mark. Our friend then proceeded to build his house. The very next spring, it was flooded.
He told us that the next time he saw the professor, he braced him with this fact, and the learned man replied: "All I can tell you is that you have 100 years coming!"
So much for "basic probabilistic reasoning."
The Fukushima power plants were required by regulators to withstand a certain height of tsunami. At the Daiichi plant the design basis was 5.7 metres and at Daini this was 5.2 metres.
Tepco has now released tentative assessments of the scale of the tsunami putting it at over 10 metres at Daiichi and over 12 metres at Dainii.
The plant sites were inundated, causing the loss of residual heat removal systems at both sites as well as emergency diesel generators at Daiichi.
I think if you look at nuclear energy purely in isolation you’d probably conclude maybe it’s best not to use it, but the fact is there’s no perfect way of generating electricity and we have to take an objective look at pros and cons on a comparative basis.
What you will see now is that all Nuke power stations in Japan will be upgraded to withstand a 9.0 earthquake and corresponding tsunami.And remember no one has died from the reactor , in fact only one worker has been exposed to dangerous level of radiation.
Every unqualified alarmist was given a free run to spread fear, and the few true nuclear experts were given little opportunity to speak and none to contradict the wildest scaremongering claims.
Soon this will go down the main stream media memory plug hole...
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