Yesterday the spent fuel rod pool at Fukushima Daiichi reactor 4 caught fire. About that time instruments at the plant showed an exponential increase in radiation levels. After the fire was quenched, radiation levels fell. In the hour before I sat down to write this, there was an explosion at the same spent fuel rod pool. As I write, another fire is burning there. NHK reports the radiation level – 300 to 400 milliSieverts – is so high that firefighters cannot approach the area.