A lot of people have been saying a lot of things about the nuclear emergency in Japan, much of it conflicting, and therefore much of it wrong. I see no reason why I shouldn’t get involved. As with almost everything else I talk about here, I claim no expertise beyond an amateur interest in the subject. Make of that what you will.
To start with, Dr Josef Oehmen, a research scientist at MIT, originally posted a pretty good description of the situation in Fukushima at the Morgsatlarge blog, explaining “Why I am not worried about Japan’s nuclear reactors.” That document has since been taken over and expanded by some folks at the MIT Department of Nuclear Science and Engineering, and it’s now available at the MIT NSE Nuclear Information Hub here, although the new authors disavow the original title.
Scott Greenfield has of course expressed a bit of skepticism:
[B]eliefs in the promise of science and safety have been certain before, and ultimately proven wrong. Afterward, everybody says how obvious is was that the work was shoddy, the systems inadequate, the science lacking. It’s always afterward that everybody knows better.
I’ve seen that a few times myself. I think the most common cause is that expert opinions are being filtered. Sometimes it’s intentional manipulation by interested parties, but sometimes it’s just the news media going with the story that’s easiest to tell.
Is anybody else old enough to remember the comet Kohoutek? It was detected in the spring of 1973, and some experts thought it would be an incredible sight in the night sky when it arrived at the end of the year–a big beautiful “Christmas Comet.” Other experts were predicting a much less spectacular show. Guess which ones got the most airtime?
When Kohoutek proved to be little more than another speck in the night sky, the news story changed. Early on, scientists had had different theories about whether Kohoutek was a new comet, which would give off a lot off a large gaseous tail when it arrived, or an old comet, which had already given off most of its gases in previous passes around the sun. Once Kohoutek arrived, scientists knew it was an old comet which couldn’t possibly have produced a big showy tail. The comet’s arrival provided actual data, which killed the alternative theories.
On the other hand, sometimes the experts are just ignorant: Nobody knew the thing could happen that way, but now that it’s happened, we understand it, and it seems obvious. Wind loading on tall buildings is a good example: Hundreds of years ago, a lot of tall church towers crumbled to the ground before people figured out that wind was rocking the tower back and forth, grinding away the mortar between the bricks. Nowadays, planning for wind loading is a routine part of structural engineering.
In the comments, Jeff Gamso adds his own cynical twist:
When the experts tell me everything is under control and there’s no need to worry, my worry increases exponentially.
I know exactly what he means. Those pronouncements are never as reassuring as the speaker thinks they are. I cringe whenever I hear that authorities are trying to “reassure the public” or “calm fears.” I don’t want to be reassured, and I don’t want to be calmed. I want to be informed and, if necessary, helped. I don’t want to be manipulated into trusting some “authority” who’s obviously trying to spin a disaster.
In my admittedly limited experience, however, it’s not the actual experts who give false reassurances. Doctors will tell you when you’re really sick. Accountants will tell you when you’re really broke. Engineers will tell you when the bridge is going to fail. The people who will try to soften the news are the public information officers, the industry spokesmen, the public relations flacks, the executives, and the politicians.
Worst of all, however, are the people with political axes to grind. Thankfully, most Americans–myself included–are completely ignorant of Japanese politics, so the media was unable find clear sides to turn this into a horse-race issue. All we’ve had until now is the basic nuclear power debate, in which the anti-nuclear folks shout and point at the dangerous happenings in Japan, and the pro-nuclear folks “tut, tut” that everybody is worried about a little steam and some radiation only slightly above the background.
Lately, however, I’ve noticed that pundits have hit upon the idea of tying the Japanese nuclear emergency to the future of U.S. nuclear energy policy, thus pulling the debate into a familiar and wasteful left v.s. right argument.
All of this makes it kind of hard for those of us watching from a distance to figure out what’s going on, which is why a relatively technical source like the aformentioned MIT NSE Nuclear Information Hub is useful for people who want to figure this stuff out. The MIT folks seem fairly sure that this isn’t going to turn into a big accident, but despite what they’ve written, there are four things that worry me.
My first worry is in regard to this statement from the MIT engineers:
The entire primary loop of the nuclear reactor–the pressure vessel, pipes, and pumps that contain the coolant (water)–are housed in the containment structure. This structure is the fourth barrier to radioactive material release. The containment structure is a hermetically (air tight) sealed, very thick structure made of steel and concrete. This structure is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown.
It’s the “tested” part that concerns me. I’m sure the engineers did all the simulations to test the design, and I’m sure they conducted a variety of heat and pressure tests on the components of the containment, but I’m also quite sure that no one has ever subjected a containment structure to a full-scale test with a full load of reactor fuel. That would be insanely dangerous, anywhere on on Earth. So nobody knows for sure that the containment will function as planned.
That leads to my second concern:
The earthquake that hit Japan was several times more powerful than the worst earthquake the nuclear power plant was built for (the Richter scale works logarithmically; for example the difference between an 8.2 and the 8.9 that happened is 5 times, not 0.7).
Some people have taken the reactor’s survival of such a severe quake as an engineering triumph, and in a way they’re right. However, I’m pretty sure the containment structures haven’t been carefully inspected since the quake, so all we know is that the containments were still standing and still pressure-tight. But just because the containment buildings didn’t collapse and spill out their contents during the quake doesn’t mean they haven’t suffered serious damage. The real question we need to answer is whether the containments are still up to spec. Can they still to the job they were designed for? Can they still contain a nuclear meltdown?
(Some people believe that the containment of reactor 2 has sprung a leak–it lost pressure after an internal explosion, and the external radiation levels shot up.)
My third concern:
All of this, however shocking it seems to us, is part of the day-to-day training you go through as an operator.
I don’t think that’s true anymore. I think this situation is not one covered by the training manuals, as evidenced by the fact that the plant workers are making mistakes, like letting the seawater pump for reactor 2 run out of fuel, causing the core to be exposed.
Finally, there’s the question of the spent fuel pools.
When reactors are shut down, the decay heat slowly tapers off, and after a month or so, the fuel rods can be removed and placed in storage at the reactor site. They are still giving off heat, so they have to be submerged in a pool of cooling water for several years until they can be transfered to long-term storage.
These pools have to be cooled and evaporated water has to be replaced. I don’t think the fuel inside can produce enough energy to melt down, but if the water is allowed to evaporate, the fuel rods will be uncovered and heat up enough catch fire, which will damage the rods and spread radioactive materials.
The spent fuel pools at the Fukushima Daiichi plant are located inside the reactor buildings, on top of the outer containment structure. That’s the top third or so of the reactor building where the hydrogen explosions took place at reactors 1 and 3. As far as I know, none of the spent fuel pools at reactors 1, 2, and 3 have caused trouble.
The fire at reactor 4 (which had been shutdown for inspection at the time of the quake) took place near the spent fuel pools, but plant officials are now saying that the fuel was not involved. They’re talking about the need to replenish the water for the pools sometime over the next couple of days.
In any case, it looks like Fukushima Daiichi is now a member of the exclusive club that includes such names as Windscale, Brown’s Ferry, Three Mile Island, and Chernobyl.
If you want to know more, I’ve found pretty good coverage of the incident by scanning CNN, Reuters, and the New York Times. If you’d like some more technical information, there are interesting stories at World Nuclear News, and the aformentioned MIT NSE site has some good explanations.