Canadian Manufacturing

Design changes blamed for California nuclear plant shutdown

The idled San Onofre nuclear power plant is facing new scrutiny from U.S. Congress



LOS ANGELES—Looks like Ontario isn’t the only jurisdiction with costly, broken-down nuclear reactors.

The idled San Onofre nuclear power plant is facing new scrutiny from U.S. Congress as its operator Southern California Edison (SCE) moves toward meeting federal benchmarks that could open the way for a restart of at least one of the reactors, perhaps in time to meet summer power demand.generators

At issue is whether Edison sidestepped any federal requirements by conducting extensive design changes, a claim leveled by an environmental group that said the alterations are at the heart of the plant’s problems.

The chair of the U.S. Senate’s environment committee pressed federal regulators to disclose details about the design of the plant’s troubled steam generators, in which hundreds of tubes that carry radioactive water have been damaged by unexpected vibration and friction.

The twin reactors, located along the coast between San Diego and Los Angeles, have been shut down for more than three months while investigators try to determine the cause of the unusual tube wear.

Sen. Barbara Boxer asked Nuclear Regulatory Commission (NRC) Chairman Gregory Jaczko for documentation on how the federal agency reviewed a series of modifications to the generators, which might be the culprit in the mechanical trouble. Boxer, who chairs the Environment and Public Works Committee, sent a similar letter to SCE parent Edison International.

“Concerns have been raised that design changes in the steam generators contributed to accelerated wear in tubes carrying radioactive water,” wrote Boxer.

Earlier this month Edison asked to restart the seaside reactors at lower power—at least for several months—because engineers believe that will ease vibration that could be eroding tubes.

However, a 13-page report issued by Friends of the Earth, a group critical of the nuclear industry, warned that running the plant at reduced power would not resolve problems with worn tubing.

The report, written by Vermont-based nuclear consultants Fairewinds Associates, suggested the best alternatives might be scrapping and replacing the costly equipment, or spending as much as $400 million on repairs.

The four generators at San Onofre each have nearly 10,000 alloy tubes that carry radioactive water.

The NRC says there is no timetable to restart the reactors, which were replaced in 2009 and 2010 in a $670-million overhaul.

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