Nuclear regulators have decided to gear up the safety assessment of two reactors operated by Tokyo Electric Power Company Holdings Inc. in central Japan, raising the possibility of finishing the process by next March, sources said Tuesday.
Reactor Nos. 6 and 7 at the Kashiwazaki-Kariwa plant in Niigata Prefecture are boiling water reactors, the same type as the ones that suffered core meltdowns in 2011 at Tepco’s Fukushima No. 1 complex.
All reactors in Japan — either BWRs or pressurized water reactors — are required to meet tougher safety criteria imposed after the Fukushima crisis, but the BWR assessment has been delayed due to the need to install safety equipment that involves extensive work.
If reactors 6 and 7 clear the assessment, they will become the first BWRs technically qualified to resume operation under the post-Fukushima rules.
Facing massive decommissioning costs and compensation payments after the Fukushima disaster, Tepco applied for the safety assessment of the two reactors in September 2013, hoping that restarting the units will help turn around its business.
But it is unclear whether the development will lead to their swift restart because Niigata Gov. Hirohiko Izumida has said he will “not talk about restarting” the reactors unless a study on the Fukushima calamity is sufficiently carried out.
The Kashiwazaki-Kariwa complex on the Sea of Japan coast is one of the world’s largest nuclear power plants in capacity if all of its seven reactors were in operation.
Allowing Tepco to reactivate its reactors can be controversial, as the utility is still struggling to scrap the crippled reactors at the Fukushima plant. Tens of thousands of people who lived nearby also remain displaced evacuees.
The Nuclear Regulation Authority decided last August to prioritize checking the two Kashiwazaki-Kariwa reactors, hoping to make them a model case of the BWR assessment process. But it retracted the decision in March after Tepco failed to offer sufficient explanation on questions raised by the regulators.
But Tepco has come up with the necessary documents and the NRA decided to reinstate the priority status of the Kashiwazaki-Kariwa reactors at least until mid-September. The NRA has conveyed its plan to other utilities whose BWRs are being checked, the sources said.
Under the new safety requirements, BWRs must be equipped with filtered venting systems so that radioactive substances will be reduced when gas and steam need to be released to prevent damage to containment vessels.
The venting facilities are not an immediate requirement for PWRs as they are housed in containers larger than those of BWRs, allowing more time until pressure rises inside the containers.
Currently, two reactors at Kyushu Electric Power Co.’s Sendai plant and another reactor at Shikoku Electric Power Co.’s Ikata plant are operating in Japan after passing the safety checks. They are all BWRs.