Defects at San Onofre Nuclear Power Plant far from resolved

The problems faced by operators of the San Onofre power plant appear to be just beginning:

California’s utility regulator may investigate how much the outage at the San Onofre Nuclear Generating Station is going to cost electricity customers.

A 95-page report released by the U.S. Nuclear Regulatory Commission on Thursday states that the generators were not properly designed to resist internal vibrations and that changes will have to be made.

Via NC Times

More details from the Nuclear Regulatory Commission’s report:

Vibrations that damaged steam generator tubes at the San Onofre Nuclear Generating Station were the result of inaccurate computer modeling by their manufacturer, according to a report released Thursday by a Nuclear Regulatory Commission inspection team. The nuclear has been shut down since Jan. 31, when a tube in one of its two reactor units sprang a leak. The other unit was inoperative at the time for planned maintenance. The NRC sent what it calls an “augmented inspection team” to the plant to investigate the cause of the leak and the response by the plant’s operator, Rosemead-based Southern California Edison. The inspection team agreed with the utility’s findings that vibrations from fluid elastic instability caused excess wear in the tubes that were less than two years old. The team further concluded that computer modeling by the manufacturer, Mitsubishi Heavy Industries, did not result in a design that provides a safety margin for vibrations, according to the report.