Robert Engel, former IAEA inspector and Swiss nuclear engineer told Reuters Sunday that a partial meltdown of a reactor “is not a disaster” and that he doubted a complete meltdown is possible. And the details of the current Japanese reactor crisis bear little similarity to the Soviet-era meltdown at Chernobyl, which came about through design flaws and human error before it spread a radioactive cloud across much of Europe and Asia 25 years ago.
Experts at the IAEA “aren’t planning for the next Chernobyl” says a mid-level Western diplomat familiar with how the organization works. “But nor do [they] think we are out of the woods yet. The reactors are still hot. But this situation has no relation to Chernobyl, even though I realize that in the popular lore, if you say ‘Chernobyl,’ it means 'catastrophic meltdown.' ”
Key differencesThe Chernobyl Soviet RBMK-1000 reactor exploded on April 26, 1986 after inexperienced handlers took the power down and then tried to power it up too quickly in an effort to discover whether a 40-second power gap in the cooling system could be bridged.
The Chernobyl reactor was new, it was undergoing tests, and it had very little structural containment measures to ward off a meltdown.
The Japanese reactors are a completely different design known as Boiling Water Reactors, which are old and tested, and have three quite elaborate systems of containment designed to constrain radioactive leakage, points out Josef Oehmen, a research scientist at the Massachusetts Institute of Technology (MIT) in Cambridge, Mass. “The third containment is designed, built, and tested for one single purpose: To contain, indefinitely, a complete core meltdown,” he writes.
Robin Grimes, director of the Centre for Nuclear Engineering at Imperial College London, told Reuters that the core of the Japanese reactors may be still intact.
"After it's all cooled down, it may well still be possible to simply remove the fuel and dispose of it in a relatively normal procedure," said Mr. Grimes. "What's clear, because of the incidental radiation being released at the moment, which is significant but not overwhelming, is that the structure of the core is probably still intact. So it's not as bad as Three Mile Island."
13 March 2011
Chernobyl as Precedent?
the Christian Science Monitor has an interesting post up as to why the unfolding events in Japan are not best compared with Chernobyl, though it is clear that the event is not over yet.