Reactions to Shika 1 criticality

20 March 2007

[Reuters, 15 March; Asahi, IHT, 17 March] Two Japanese nuclear utilities, Chubu and Tohoku, have admitted incidents involving fallen control rods similar to that which caused a criticality at Hokuriku's Shika 1 in 1999. In all three events, boiling water reactors were shut down for inspections when control rods slipped from their proper positions. In the case of Shika 1, this initiated a criticality that lasted 15 minutes and should have been reported by law. Hokuriku's Toshihiko Takahashi described his company's actions as a "cover up." In the other incidents, which occurred eight and 11 years earlier under different legislation, the fallen rods were too far apart for criticality to occur. Both the Japan Atomic Energy Commission and the Ministry of Economy Trade and Industry condemned past secrecy of nuclear operations and called for increased sharing of experience, which they said could have prevented the Shika 1 incident.

Further information

Chubu Electric Power Company
Hokuriku Electric Power Company
Tohoku Electric Power Company

Japan Atomic Energy Commission
Ministry of Economy Trade and Industry

---