The Nuclear Regulation Authority will prioritize air conditioning and ventilation pipe checks at key facilities of nuclear power reactors that have passed safety screenings, including plants already brought back online.
The decision Wednesday came after significant corrosion and holes were found in ventilation pipes in the central control room for the No. 2 reactor of Chugoku Electric Power Co.’s Shimane nuclear plant in Matsue, Shimane Prefecture.
The problem was discovered when the power company last month removed heat-insulating covers from the pipes for the first time since the reactor went into operation in 1989. Chugoku Electric reported this to the NRA, concluding that the pipes were not functioning properly.
The secretariat for the NRA plans to urge utilities to swiftly inspect pipes at important facilities by removing heat-insulating materials that cover the pipes. The key facilities in question are the central control rooms and rooms to be used as emergency centers in the event of a severe accident.
The firms will also be asked to carry out the pipe checkups for reactors that have not cleared the NRA’s safety screenings.
The inspections can also be conducted at operating reactors, according to the NRA.
New nuclear safety standards were introduced in July 2013, following a triple reactor meltdown at Tokyo Electric Power Company Holdings Inc.’s Fukushima No. 1 nuclear plant, which was heavily damaged in the March 2011 earthquake and tsunami.
Among reactors that have passed the authority’s safety checks are the No. 1 and No. 2 units at Kyushu Electric Power Co.’s Sendai plant in Kagoshima Prefecture, and the No. 3 unit at Shikoku Electric Power Co.’s Ikata plant in Ehime Prefecture.
Currently, only two reactors — the Sendai No. 1 reactor and the Ikata No. 3 reactor — are in service.
The regulator said that if a hole is found in a pipe at a key nuclear reactor facility, its operator must fix it within 10 days. If it fails to do so, operations at the reactor must be suspended.
Toyoshi Fuketa, an NRA official in charge of screenings, called on power company officials to check pipes by removing the covers and viewing them in person.
Also subject to the checks are pipes at Japan Nuclear Fuel Ltd.’s spent fuel reprocessing plant in Aomori Prefecture and the Japan Atomic Energy Agency’s Monju prototype fast-breeder reactor in Fukui Prefecture, which the government recently decided to decommission.