Planned and unplanned shutdown at Diablo Canyon halts all electricity generation

Nov 10, 2020

In San Luis Obispo County, Pacific Gas & Electric says it still can’t say when Diablo Canyon will restart sending electricity to California’s grid. The nuclear power plant has been completely offline since mid-October, generating no electricity while workers do maintenance and do repairs.

Update: PG&E announced on Nov. 9 that Unit 1 is once again online after workers finished a "planned refueling and maintenance outage that began in early October."

The partially unplanned shutdown doesn’t pose a radiological danger, says PG&E—and David Weisman of the Alliance for Nuclear Responsibility (A4NR). But according to plant watchers, a stator—a part in the main electrical generator—failed, for the second time since it was installed last year, according to Weisman.

The failed part was replaced “at a cost of over $100,000,000 dollars to ratepayers, because we were told it was integral for those remaining few years of the plan to make this investment,” Weisman said. “Well, this new piece of equipment has failed for pretty much the same reason as the piece it replaced had failed—It seems to have developed a hydrogen leak.”

PG&E spokesperson Susanne Hosn said “at this time, there are no indications of a stator malfunction.” Hosn also confirmed the utility is “continuing inspections and developing repair plans as both Unit 1 and Unit 2 of the nuclear power plant are removed from service.”

Asked when Unit 2 would be fixed, Hosn replied in an email, “for market considerations, we are not able to answer your question regarding how long the unit will be offline. We will issue a media release when the unit is returned to service.”

Weisman said the shutdown serves to contradict arguments from groups like the nuclear power advocates Californian for Green Nuclear Power for keeping the plant in operation beyond its planned decommissioning in 2024 and 2025. Those arguments include the position that commercial nuclear power plants are more reliable than renewable energy sources like solar and wind.

But more worrisome to the A4NR and other anti-nuclear groups is what they say is a lack of oversight of the plant in its few remaining years before it’s shuttered for good. This year, the federal Nuclear Regulatory Commission (NRC) made moves to relax regulations on commercial nuclear power plants.

“And then we have Pacific, Gas and Electric, a company that's barely emerged from bankruptcy [and] has been found guilty of gas explosions [and] fire-related deaths,” Weisman said. “We have a utility that needs to be watched by the very regulators who don't seem to be watching it.”

PG&E’s Hosn says there are on-site NRC inspectors at Diablo Canyon Power Plant, and that PG&E will “perform additional tests as part of the process to return the unit to service.”