Significant portions of major geological faults running under Tohoku Electric Power Co.’s one-reactor Higashidori nuclear power plant in Aomori Prefecture are probably active, a Nuclear Regulation Authority panel said in a draft report Monday.
The faults apparently do not run directly beneath the complex’s reactor but the assessment indicates the unit may have to remain offline for quite some time because the utility will need to reassess the plant’s quake resistance and take measures to reinforce the facilities.
The draft report, which was a summary of discussions among panel members, also touched on the need to further study other smaller faults that run underneath an area close to the reactor building.
Nuclear plant operators are banned from building reactors and related facilities important for safe atomic power output directly above active faults, and it’s possible that some faults were not detected or identified as active at the time plants were built, as suggested by recent fault probes at other atomic facilities.
Officials of Tohoku Electric, who also attended the discussions, said the utility will conduct additional geological surveys, taking into account the opinions it has received from the panel.
But the utility maintained its argument that there are no active faults on the plant’s premises. Executive Vice President Takeo Umeda said later in the day that one of the major purposes of the surveys is to “properly explain that there are no activities” in the faults. The utility plans to compile the results of the surveys in December.
The panel plans to finalize the draft report after listening to the opinions of other experts who have been tasked by the NRA to cooperate in the investigation of faults at other nuclear plants.
Government in lawsuit
The central government was named Monday in a lawsuit filed by local residents seeking the decommissioning of Chubu Electric Power Co.’s Hamaoka nuclear power plant.
The plaintiffs are demanding that the government bar Chubu Electric from restarting the nuclear plant in the coastal city of Omaezaki, Shizuoka Prefecture.
The demand on the government was added to the complaint when it was updated the same day. The update, the lawsuit’s fifth, was submitted by the plaintiffs’ lawyers to the Hamamatsu branch of the Shizuoka District Court.
The update listed an additional 155 plaintiffs, bringing the total number suing to 336.