Tokyo Electric Power Co. started its first plutonium-thermal power generation, known as "pluthermal," at its Fukushima No. 1 nuclear power plant Saturday morning, the utility company said.
The launch came after Tepco had trouble starting up the No. 3 reactor at the power plant in Okuma, Fukushima Prefecture, and postponed the activation initially scheduled for Friday evening.
Tepco said the alarm light indicating the conditions of the pipe valve for the emergency core cooling system didn't function properly. There were no problems with the pipe or the valve, according to the company.
The No. 3 reactor achieved a self-sustaining nuclear chain reaction in the early afternoon and actual power generation is expected to begin in several days, Tepco said.
The reactor is the third in Japan used for pluthermal generation, following Kyushu Electric Power Co.'s Genkai plant in Saga Prefecture and Shikoku Electric Power Co.'s Ikata plant in Ehime Prefecture.
Tepco plans to start commercial operations at its reactor after a final government inspection scheduled for Oct. 26.
Pluthermal, a Japanese word that combines "plutonium" and "thermal," uses plutonium-uranium mixed oxide fuel, known as MOX.
Tepco had initially intended to start pluthermal operations in 2000, but the plan was suspended in the wake of mismanagement involving some power companies.
Fukushima Gov. Yuhei Sato finally approved pluthermal power generation at the plant in August.