The fire followed an explosion Tuesday at the plant's No. 2 reactor and a fire in a storage pond used for spent nuclear fuel at the No. 4 reactor. Radiation levels at the plant increased to about 167 times the average dose during that fire, according to the International Atomic Energy Agency.
That dose quickly diminished with distance from the plant, and radiation fell back to levels where it posed no immediate public health threat, Chief Cabinet Secretary Yukio Edano said.