Alarm forces Unit 6 at Kashiwazaki-Kariwa offline hours after restart

Tokyo Electric Power Company took Unit 6 at the Kashiwazaki-Kariwa nuclear plant in Niigata Prefecture offline less than six hours after restarting it, after an alarm was triggered just after midnight on Thursday. TEPCO said the unit had been restarted at 7 p.m. on Wednesday and that the alarm sounded while technicians were adjusting control rods, the cylinders used to regulate or stop a reactor's power output.

Because the cause of the alarm could not be immediately identified, the utility halted the reactor to conduct inspections and said the plant was in a stable condition with no radioactive impact to the outside. The restart ended more than a decade of dormancy following the 2011 Fukushima Daiichi triple meltdown.

The Niigata facility, at full capacity one of the world’s largest nuclear complexes, was seen as a milestone in Japan’s effort to revive nuclear energy to meet growing demand for cleaner, stable and lower-cost electricity. TEPCO said safety was its "top priority" and that it would announce the results of its investigation as soon as possible.

The restart was a high-stakes test for TEPCO, which has struggled to regain public trust; a Niigata Prefecture survey in October found 60 percent of residents believed conditions for a restart had not been met and 70 percent expressed concerns about TEPCO’s management.

Key Topics

Business, Tepco, Kashiwazaki-kariwa, Niigata Prefecture, Fukushima Daiichi, Control Rods