Nuclear, Reactors

Poor design choices blamed for San Onofre nuclear shutdown

Designers attempting to stop one kind of vibration in steam generator tubes at the San Onofre nuclear power plant inadvertently created another kind that led ultimately to the plant’s shutdown, the LA Times reports.

Designers working on the new system in 2005 focused on controlling one type of vibration and reducing wear on the tubes by adding more anti-vibration bars, said Mitsubishi Nuclear Energy Systems senior vice president Frank Gillespie. According to the paper, in reactor Unit 3, the most heavily damaged reactor, there was half the amount of pressure between the bars and tubes as in Unit 2 because the bars were flatter.

“What they didn’t understand at the time is, some of the steps…actually made in plane [vibration] worse,” Gillespie said according to LA Times. “…There was an underappreciation for the fact that the pressure of the bars against the tubes actually performed a very important function.”

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