20 Décembre 2012
December 20, 2012
TOKYO (Kyodo) -- Japan's nuclear regulatory authority said Wednesday that recently confirmed trouble with fuel rods stored in a spent nuclear fuel pool at Tokyo Electric Power Co.'s Kashiwazaki-Kariwa plant is a level 1 incident on a 7-point international scale.
A pair of fuel rods was touching as a result of deformation in the bundle of fuel rods, leading the Nuclear Regulation Authority to determine that the fuel had likely been loaded to the reactor core "in an abnormal situation." The NRA's assessment of the incident is provisional.
According to the NRA, the flow of the coolant water through the bundle of fuel rods could be hampered if rods stick together, making it easier for heat to accumulate. The authority, however, said no leakage of radioactive substances was observed.
Level 1 on the International Nuclear and Radiological Event Scale is a stage defined as an "anomaly." The Fukushima Daiichi nuclear power plant crisis last year and the 1986 Chernobyl disaster have been assessed as level 7 accidents.
TEPCO said it found on Oct. 16 deformed sections of spent nuclear fuel assemblies in the spent fuel tank of the No. 5 unit of the Kashiwazaki-Kariwa plant in Niigata Prefecture on the Sea of Japan coast.