Earthquake-damaged Fukushima nuclear power plant triggers evacuation

Friday, March 11, 2011

Japan’s government has declared its first ever “nuclear emergency” after pressure rises in the No. 1 reactor at the Fukushima Daiichi power plant, combined with a minor radiation leak, caused a 10 km radius around the plant to be evacuated. An attempt to relieve the pressure inside the containment vessels of the plant has been delayed.

The Tokyo Electric Power Company’s 40-year old nuclear facility, 270 km NE of Tokyo, reported mechanical difficulties with its cooling system, although the automated shutdown systems worked correctly. With the core reaction shut down the plant is no longer actively generating heat, but the fuel rods continue to generate excess heat and radiation and need constant cooling.

The cooling system runs a constant flow of water to take the heat away from the submerged fuel rods, but the pumping system requires electricity to operate even after the plant is no longer producing electricity itself—generally from back-up diesel or natural gas generators.