Debunking Nuclear Reactor Fears

by Christopher Paul on March 14, 2011

Like many of us, I’m concerned for Japan in light of the massive 9.0 earthquake (revised from an earlier 8.9) that hit last week and the ensuing tsunami and nuclear cooling issues. Some might use this as an excuse to stop research into non-fossil fuel power plants in the US which would be a shame. But for those who are unaware of what could happen, you might want to read this comment left by Newsvine reader, Sam W.

Current nuclear power plants are designed around subcritical masses of radioactive material, which are manipulated into achieving sustained fission through the use of neutron moderators. The heat from this fission is used to convert water to steam, which drives electric generator turbines. (This is a drastic simplification.) They are not capable of achieving supercritical levels; the nuclear fuel would melt before this could occur, and a supercritical reaction is required for an explosion to occur.

When the earthquakes in Japan occurred on March 11th, all ten reactor cores “scrammed”, which means that their control rods were inserted automatically. This shut down the active fission process, and the cores have remained shut down since then.

The problem is that even a scrammed reactor core generates “decay heat”, which requires cooling. When the tsunami arrived shortly after the earthquake, it damaged the external power generators that the sites used to power their cooling systems. This meant that while the cores were shut down, they were still boiling off the water used as coolant.

I suspect he has some education on nuclear reactors (either being in the industry or a physicist) or is a really good government plant (conspiracy theory alert!). But either way, his comment is worth the read and I learned a lot about nuclear power plants, reactions, cooling, & the current crisis compared to other disasters like Chernobyl.

I should also point out that Sam W is a recent Newsvine member and only had one comment before the earthquake but it doesn’t make his ideas any less informative. It would have been nicer if he was a long time member to help show he wasn’t there for PR damage control.

Sam W. – Newsvine

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