WASHINGTON, June 19 (Kyodo) — U.S. Nuclear Regulatory Commission officials said Monday that faulty computer modeling caused problems with steam generators made by Japan's Mitsubishi Heavy Industries Ltd. for a nuclear plant, the Los Angeles Times reported Tuesday.
The problems are expected to force the San Onofre nuclear plant in California to remain out of service through the summer, according to the report.
The plant has been offline since early this year when a small leak was discovered in one of the thousands of steam generator tubes that carry radioactive water to create steam for turning turbines.
"That led to the discovery that other tubes were rubbing against support structures and adjacent tubes, and wearing out more quickly than expected," the newspaper said.
NRC officials were quoted as saying it appears that simulations by Mitsubishi underestimated the velocity of steam and water flowing among the tubes.
The high rate of flow caused the tubes to vibrate and knock against each other, leading to the wear, the newspaper said.
The paper quoted one NRC official as saying ultimate responsibility lies with Southern California Edison which has operated the nuclear plant.
An environmental group contends that when Southern California Edison replaced the steam generators, it failed to report a series of design changes that should have been reviewed by the NRC and sidestepped public scrutiny of the changes, the paper said.
