Kyushu Electric Power Co. and Chugoku Electric Power Co. decided Wednesday to decommission two aging reactors, following a similar move the previous day by the operators of two other nuclear power plants, amid safety concerns in the wake of the 2011 Fukushima nuclear crisis.
Kyushu Electric’s board decided to scrap the No. 1 reactor at the Genkai plant in Saga Prefecture, and Chugoku Electric Power Co. decided to decommission the No. 1 reactor at the Shimane plant in Matsue, Shimane Prefecture.
A regulation brought in following the March 2011 nuclear disaster at Tokyo Electric Power Co.’s Fukushima No. 1 plant forbids nuclear reactors from operating for more than 40 years in principle, but they may be allowed to continue operating for another 20 years if the operators make safety upgrades and the unit passes the regulator’s screening.
Demolishing the five aging nuclear reactors would generate more than 20,000 cu. meters of radioactive waste, but no decision has been made on possible disposal sites.
The waste that needs to be buried underground would fill more than 100,000 barrels, said officials at the Agency for Natural Resources and Energy. Unless sites are chosen, the waste will need to be temporarily stored within nuclear power plant sites after the reactors are dismantled.
Operators of aging plants are facing a tough decision as huge amounts of additional investment are needed to meet the new safety requirements to keep reactors operating beyond 40 years.
On Tuesday, Kansai Electric Power Co. and Japan Atomic Power Co. decided to scrap a total of three old reactors.
Kansai Electric will decommission the No. 1 and No. 2 reactors at its Mihama power plant. Japan Atomic Power Co. plans to decommission the No. 1 reactor at its Tsuruga power station. Both plants are in Fukui Prefecture.
According to the agency, low-level waste generated during demolition of the five reactors would total 21,788 cu. meters, based on estimates by the power firms as of the end of March 2014.
So-called L1 category items, the most radioactive, such as the control rods inserted into the fuel to halt criticality, must be buried at least 50 meters below ground. A total of 533 cu. meters of such waste is expected to be generated by the five reactors.
L2 category items, such as filters and waste liquid, would total 5,105 cu. meters. L3 category items, which are the least radioactive, would amount to 16,150 cu. meters, according to the estimates.