Japan’s Nuclear Regulation Authority (NRA) has decided that operators of boiling water reactors (BWRs) will be required to install new emergency cooling systems to be activated in the event of a severe accident.

The new regulation means that emergency cooling systems must be installed at some BWRs that are currently undergoing checks in preparation to restart. They include Tohoku Electric Power Co’s Higashidori nuclear plant in Aomori Prefecture and its Onagawa plant in Miyagi Prefecture, as well as Chubu Electric Power Co’s Hamaoka plant in Shizuoka Prefecture.

While several pressurised water reactors have cleared the stricter safety standards introduced after the Fukushima disaster, two reactors at Tokyo Electric Power Company’s (Tepco’s) Kashiwazaki-Kariwa power station in Niigata Prefecture were the first BWRs units to be approved earlier this month. Tepco, which also operates the Fukushima plants, had already planned to install the new emergency cooling system for Kashiwazaki-Kariwa 6&7, which NRA has now made a requirement. It will formalise the decision after soliciting public comment on the rule change.