March 16, 2011

Nuke nomenclature

As the MSM commentariat has become stupider and stupider, it becomes increasingly difficult to tell just what the hell is going on in Fukushima, or, alternatively, just what the Fukushima is going on in Hell.

Terms seem to get used interchangeably. "Containment vessel," "reactor building," "containment structure," et cetera. At the bottom of all this ambiguity is the simple reality that the reporters don't really understand what they're talking about. This has become a major problem in recent years as one tries to follow a big story like the nuclear disaster in Japan.

I do not profess to be any kind of expert on Japanese nuclear plant design, but just looking at the pictures and diagrams, it doesn't really seem all that complicated. Working from the inside out, you have the reactor pressure vessel, which is built along the lines of a tank car in a railroad train. It is made out of very thick steel. Inside the reactor vessel you have the nuclear fuel rod arrays which are immersed in water (to slow the neutron exchange and to cool the fissile process).

At the next level, you have the secondary concrete shield wall. This is an added level of safety which was not present, for example, at Chernobyl. This is a steel-reinforced concrete structure surrounding the reactor vessel.

Lastly, you have the reactor building, which is another, larger box (a building) surrounding the other two structures. It's also made out of concrete. One might think of the whole thing as Satan's Russian Doll.

The fuel storage pool is apparently inside the reactor building and above the containment structure, sort of like a shelf or drawer built below the reactor building roof. These are approximate cubes about 40 feet on a side, filled with bluish, boronated water.

Somehow or other, there have been a number of violent explosions at Fukushima reactors Nos. 1,2 & 4, and in one case at least it apparently blew the roof off the reactor building (No. 2) and in No. 4 blew two 8-meter holes in the side of the reactor building. Here is what (among many things) is troubling about the explosion in Reactor #4: it apparently originated in the spent fuel pool. Trying to reason through this logically, how does an explosion blow holes in the side of the reactor building (see diagram above) without blowing holes in the side of the spent fuel pool?

I suppose it's technically possible, but the confused reporting about what's going on never attempts to explain this clearly. This would appear to be the most severe threat posed to Japan, since the spent fuel rods (or nuclear waste) are huge repositories of all kinds of radioactive stuff. If, as the nuclear site reports, there is extensive damage to nuclear cores within several reactor pressure vessels, but the vessels themselves are still intact (as appears to be the case), then the most logical explanation for the very high levels of radiation being recorded onsite would seem attributable not to the occasional steam releases intentionally performed by the staff but to exposed (uncovered by water) spent fuel rods in one or more storage pools fizzing away their radioactive cesium, iodine, strontium, plutonium and other diabolical stuff. Quite understandably, it's hard for the onsite staff to observe what's going on directly because they don't want to go near the thing.

I don't know, and I know the New York Times will never be able to tell me in comprehensible terms. But I suspect that what's really going on is that there is at least one spent fuel pool with holes in the wall, to put the matter simply, and that the coolant water is leaking through those walls faster than it can be replaced (since the Japanese have no good options for replacing it rapidly). And that the spent fuel rods, as a result, are exposed to air, the zirconium cladding is oxidizing away, and a witch's brew of toxic crap is spewing into the atmosphere.

Only a hunch. Nuclear power plants. As one guy said way back in 1980, it's a lot like using a pile driver to crack walnuts, this business of employing a nuclear chain reaction to boil water. Absolutely fraught with risk, at every stage of production.

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