Two Missteps at San Onofre Nuke Plant Didn't Pose Threats, NRC Says

According to a Nuclear Regulatory Commission report from the most recent inspection of the San Onofre Nuclear Generating Station, two minor problems surfaced.

One was that workers had incorrectly hooked up a water line to a refueling water tank so it would feed the spent-fuel rod cooling pools, but workers didn’t write down that they did it. The line remained hooked up wrong for a few months, rendering the safety function of the system ineffective during that time.

Victor Dricks of the NRC said this wasn’t that big of a problem because first, it was quickly remedied. Second, the safety system wouldn’t have gone into action except during a certain highly improbable level of earthquake in the area, according to seismic data.

But perhaps most important, Dricks said, is that other systems were designed to fill the role of the water tank if it, too, were to fail. Southern California Edison spokesman

“Although San Onofre’s first-quarter performance showed improvement compared to previous quarters, we are not satisfied,” Alexander said in response to the May NRC report. “We will continue to identify and correct instances of worker and management behavior that are not consistent with industry excellence.”

Another finding showed that rain had leaked through the roof of one of the San Onofre plant’s emergency diesel generator buildings because no one cleaned leaves out of the gutters. In response, workers had covered the mechanics with plastic tarps.

The NRC report said that the functioning of the equipment wasn’t compromised but that the incident showed that the plant hadn’t planned for “seasonal readiness” and that its maintenance program, at least for that diesel building, seemed “reactive.”

The report linked this to but that the NRC says have improved drastically since the beginning of the year.

Dricks reiterated that the two findings were of low safety significance and that the fact that the NRC found them shows the inspection system works.

"We maintain a high level of oversight," Dricks said. "We have rigorous standards and a low threshold for concern."

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