TAKAHAMA, Fukui -- A large crane fell on a reactor auxiliary building and a fuel handling building at the No. 2 reactor of the Takahama Nuclear Power Plant in Fukui Prefecture on the night of Jan. 20, damaging part of their roofs, Kansai Electric Power Co. said.
There were no injuries in the incident, nor were there any leakages of radiation to the outside environment, the power company said. A storm warning had been issued in the prefecture, with strong winds at a speed of about 15 meters per second (54 kilometers per hour) observed near the plant at the time of the incident, which occurred at around 9:50 p.m.
The 112.75-meter mobile crane, as well as three other similar cranes, was installed for work to refurbish plant facilities in accordance with the new safety standards introduced in the wake of the Fukushima No. 1 Nuclear Power Plant disaster. The collapsed crane was intended for work to install a new dome above the No. 2 reactor's containment vessel. After the incident, the framework of the collapsed crane was seen bent along the buildings on which it fell, and the metal rails on the edges of the roofs of the two affected buildings were damaged.
According to Kansai Electric Power Co., a worker at the plant's central control room heard a loud sound and checked to find one of the four cranes collapsed. When a Kansai Electric employee visually checked the inside of the fuel handling building, where 259 nuclear fuel rods are stored in a pool, there were no objects that had fallen upon them. The utility said there were no effects from the accident on the fuel pool or the fuel rods.
"We are sorry for causing concern," said Masakazu Takashima, a senior official at the Takahama plant, at a press conference, suggesting that work involving large cranes would be suspended at the plant for the time being. With regards to the strong winds in the area at the time, he said, "We thought it would be all right after calculating the effects from the wind. However, we hadn't taken wind direction into consideration." Takashima said the cause of the incident had yet to be identified.
The Nuclear Regulation Authority (NRA) in June last year granted permission to extend the operation of the plant's No. 1 and No. 2 reactors, making them the country's first reactors to be allowed to operate beyond 40 years.
According to the NRA, the management methods for protecting nuclear plant facilities are provided for by each plant's safety code. Nuclear safety inspectors stationed at each plant monitor to see if work is in progress as specified by the safety code and conduct safety inspections four times a year. While no work was underway at the time of the crane collapse as it was during the night time, the NRA will investigate if work and equipment were properly managed in accordance with the rules as a storm warning had been issued in the prefecture at the time.
"We will check if the series of work involving the cranes had been properly managed to the effect that it wouldn't affect nuclear reactor facilities," said an NRA official.