There have been several reports of a fire at a spent fuel facility at the Fukushima nuclear power plant in Japan, where plant operators are struggling to cool down reactors. There were also spikes in radiation measurements in the area. The fire has since been extinguished.

From the New York Times:

Japan’s nuclear watchdog said a pool storing spent fuel rods at [a] fourth reactor had overheated and reached boiling point and had become unapproachable by workers. The fire earlier Tuesday morning was sparked by a hydrogen explosion caused by rising temperatures at the fuel pool, which released radioactivity directly into the atmosphere. The government said late Tuesday that radiation levels at the plant also appeared to be falling sharply from levels earlier in the day.

The fourth reactor had been turned off and was under refurbishment for months before the earthquake and tsunami hit the plant on Friday. But the plant contains spent fuel rods that were removed from the reactor. If these rods had become dry, they could overheat and catch fire.

That is almost as dangerous as the fuel in working reactors melting down because the spent fuel can also spew radioactivity into the atmosphere.Shigekatsu Oomukai, a spokesman for the Nuclear and Industrial Safety Agency, said the substantial capacity of the pool at reactor No. 4 meant that the water in it was unlikely to evaporate soon. But he said workers were having difficulty reaching the pool to cool it because of the high temperature of the water.Worryingly, temperatures appeared to be rising in the spent fuel pools at two other reactors at the plant, No. 5 and No. 6, said Yukio Edano, the chief cabinet secretary.