Japan’s largest builder of nuclear power plants plans to check for defective workmanship at five reactors, following an extortion bid by a former subcontractor employee who claimed he had deliberately underwelded parts.
A spokesman for Tokyo-based Mitsubishi Heavy Industries Ltd. described the checks as precautionary, stating that computer simulations indicate there are no safety risks even if the man’s claims are true.
Mitsubishi Heavy recently received three letters from a man who used to work for one of the company’s subcontractors in Hyogo Prefecture. The letters state that the man had underwelded plates used to support pumps in the steam generators of nuclear plants, according to MHI spokesman Hiroyuki Yamakado.
The man threatened to inform the utilities that operate the plants unless Mitsubishi Heavy instructed the subcontractor to pay him 40 million yen, Yamakado said.
He added that Mitsubishi Heavy had alerted police and was preparing to carry out safety checks in conjunction with the operators of five reactors in western Japan that may have used parts from the subcontractor.
One of the operators, Kansai Electric Power Co., said Wednesday its workers have already visually inspected the plates in question at two of its reactors and found nothing unusual. The company will conduct ultrasound checks on the welds, Kepco spokesman Kimihito Kawabata said.
A Hyogo police spokesman confirmed that Mitsubishi Heavy reported the threatening letters, but he declined further comment.
Yamakado declined to name the subcontractor or its former worker.