12 March 2011: Women, Japan, Nuclear Reactors

I am drinking my coffee and will go for a short “before breakfast” run soon. I am a bit stiff from yesterday’s afternoon 8 mile walk.

Japan’s nuclear plant trouble

Here is a relevant article

My take: disclaimer: I haven’t worked with nuclear power plants since 1984 and I worked on a different type of plant. So, I am no expert.
The plant in question is the Fukushima reactor plant; this plant has several “boiling water reactors”. These reactors use water which goes through a reactor and boils; this steam (which is radioactive) turns the blades of a turbine which generates electricity. The steam is then condensed into water and pumped through the core again.

The problem: while the reactor has been shut down (no more fissions) by the control rods, there is a significant amount of heat that comes from the radioactive decay of the so-called “fission products” (the newly formed atoms that are left after the uranium atoms split); depending on reactor design this can amount to well over 10 percent of full power. I don’t know what percent of full power that decay heat makes up in this particular design.

A lack of cooling water could cause the reactor to overheat thereby causing the fuel pellets to melt down, at least partially. Of course there are other issues: steam pressure in the primary circuit (the steam-water circuit that normally runs between the reactor and the turbines), radioactive gasses in the steam that are released, etc.

Of course many things could have caused the explosion that you just saw, and many of the possible causes are not-nuclear related.
So we’ll have to wait and see.