KAGOSHIMA - Japan restarted its first nuclear power plant on Tuesday morning under stricter safety standards that were introduced in July 2013 after the Fukushima disaster in 2011.
Kyushu Electric Power Co. restarted the No. 1 reactor at its Sendai nuclear power plant (see below) in Satsumasendai, Kagoshima Prefecture, ending a 23-month period in which no nuclear reactors were operating in Japan after the No. 4 reactor was shut down at Kansai Electric Power Co.'s Oi nuclear power plant in Oi, Fukui Prefecture.
The No. 1 reactor reached a self-sustaining chain reaction, or criticality, at around 11 p.m. on Tuesday.
Workers at the Sendai plant started raising control rods, which suppress nuclear fission reactions, at 10:30 a.m. by remote control from a central control room.
Kyushu Electric will then drive the reactor's turbine to generate and transmit electricity on Friday before reaching its full capacity of 890,000 kilowatts sometime around Aug. 20.
The No. 1 reactor remained dormant since it was brought offline for regular checkups in May 2011.
Kyushu Electric could have restarted the reactor on Monday when all necessary inspections were complete, but decided to wait until Tuesday because of concerns over possible teething problems since the reactor had remained idle for an unprecedentedly extended period.
The nation's nuclear reactors were shut down after the March 2011 earthquake and tsunami damaged Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant.
The Nuclear Regulation Authority rolled out new regulation standards two years later. Operators have applied for safety screenings to be conducted for 25 reactors at 15 power plants.
Sendai's No. 1 reactor, along with its No. 2 reactor, became the first to pass the NRA screening in September last year. Kyushu Electric is aiming to restart the No. 2 reactor in mid-October.
Screenings have been under way for other reactors, with three already approved - the Nos. 3 and 4 reactors at KEPCO's Takahama plant in Fukui Prefecture and the No. 3 reactor at Shikoku Electric Power Co.'s Ikata complex in Ehime Prefecture.
The time frame to restart the Takahama reactors remains unclear since the Fukui District Court issued an injunction in April ordering KEPCO not to do so.
Japan has increasingly relied on thermal power generation as more and more nuclear reactors were suspended.
Faced with soaring costs to purchase crude oil, liquefied natural gas and other fossil fuels, operators were forced to hike household electricity rates. KEPCO and Hokkaido Electric Power Co. had to raise their electricity charges twice because of their deteriorating financial state.
■ Sendai nuclear power plant
The facility houses two reactors. The plant's No. 1 reactor became operational in July 1984, and the No. 2 reactor went online in November 1985. Each can generate 890,000 kilowatts. Unlike the boiling-water reactors at the Fukushima No. 1 nuclear power plant, Sendai's are pressurized light-water reactors featuring relatively large containment vessels