California’s Embrittled Diablo Nuclear Plant Now in Court

Diablo Canyon Power Plant, on the coast of California.

Diablo Canyon Power Plant, on the coast of California. Photo by Doc Searls.

The infamous atomic reactors at Diablo Canyon are headed to federal court. Their epic case could decide the economic and ecological fate of the nation.

The key issue—-embrittlement—-may seem obscure. But it’s at the center of whether a melting atomic reactor will calmly cool down or explode in a violent planetary apocalypse.

To support forcing full scrutiny of all of Diablo’s critical safety issues, go to

The twin Diablo atomic cores, burning about nine miles west of San Luis Obispo on the central California coast, were designed and largely built in the 1960s and ‘70s. Over the decades, fierce public opposition has made them the site of more civil disobedience arrests (around 10,000) than any other US reactors.

In 1984, as the protests were winding down, Pacific Gas & Electric had to admit it had installed a major multi-ton component backward. Already hugely unpopular, PG&E ignored the uproar, flipped the machinery, and forced the plant online anyway.

In 2010 the company’s badly maintained gas lines in San Bruno exploded, incinerating 19 homes and 8 humans. It later admitted to 8 federal charges of involuntary manslaughter.

In 2017 the company’s badly maintained power lines ignited fires throughout northern California that incinerated the town of Paradise and killed more than 80 people. It later admitted to more than 80 federal charges of involuntary manslaughter.

The company agreed to phase out the two Diablo reactors a year prior. In a high-profile blue ribbon ceremony, PG&E signed an extensive contract with then-Governor Jerry Brown, then Lieutenant-Governor Gavin Newsom, the state legislature, the California Public Utilities Commission, local town governments, major labor unions, local, state and national environmental groups and others. The unprecedented agreement said the reactors would shut in 2024 and 2025, when their 40-year Nuclear Regulatory Commission licenses would expire. Their power would be replaced by renewables, primarily wind and solar.

But last year Newsom—-now Governor—-strong-armed the legislature and the CPUC into a deal meant to keep both reactors running for at least five more years, probably longer.

The reversal has infuriated California’s renewable energy community—and will now face the nation’s most critical federal court challenge in decades.

Its focus on embrittlement dates back thirty years. In 1991, lighting struck the Yankee Rowe atomic reactor on Massachusetts’ Deerfield River. At thirty years of age, Rowe was then among the oldest nuclear plants running in the US. Experts worried that the intense heat, pressure and radiation inside the reactor core had changed the chemical composition of key metal components, making them so brittle that if hit with the cold water needed to stop a runaway meltdown, they would shatter.

Under such circumstances, steam, hydrogen, and radiation could combine for an explosion of apocalyptic proportions, with incalculable human, ecological, and economic costs.

In a contentious hearing (at which I testified) before US House committee, Rep. Peter Kostmayer (D-PA), told incoming NR C Chair Ivan Sellin that Rowe should not re-start without first passing a test for embrittlement. Its owners did not run the tests. Rowe stayed forever shut.

A parallel issue now faces Diablo. Unit One was built with copper and other amalgams that were abandoned in ensuing reactors as being unsafe. Tests in 2002 showed it to be among the most dangerously embrittled nukes in the US. It has not been tested since.

On September 14, the San Luis Mothers for Peace and Friends of the Earth sued in federal court, demanding that Unit One cease operations at least until core embrittlement tests have proven it safe to operate. The groups’ Washington-based attorney, Diane Curren, represented the victorious environmentalists at Yankee Rowe in the 1990s.

Diablo One is scheduled to shut down within the next few weeks for periodic re-fueling, which should take about 50 days.

PG&E has said it will test for embrittlement during the outage. But it’s unclear how quickly they can get definitive results and what those results will be.

The NRC has long been infamous for adjusting its regulations to meet industry needs. The Commission has already committed to stretching its long-established timelines to provide Diablo with the license extensions it might need to continue operating. It allowed Indian Point Units Two and Three to operate for years without valid licenses before then-Governor Andrew Cuomo forced them to shut down because of the danger they posed to the New York City environs..

Like Indian Point and all other commercial US reactors, Diablo operates without liability insurance. A petition circulated in 2019 gathered more than 2400 signatures demanding that Unit One be thoroughly inspected before reopening from that year’s refueling outage.

Gov. Newsom ignored the request, spewing arguments that as per the 2016 agreement, both reactors would soon close.

In the interim, the administration has heavily assaulted California’s solar industry, radically reducing homeowner paybacks, crippling the economics of multiple-tenant installations and moving to heavily tax micro-grids that could allow neighborhoods to become independent of central utilities like PG&E.

PG&E has also been allowed to avoid routinely mandated reactor maintenance, safety upgrades and environmental regulation, assuming that Diablo would soon close.

That began in 2016. Despite its criminal histories at San Bruno and Paradise, Newsom says PG&E can safely clean up its maintenance short-falls without impacting the likelihood of catastrophe explosions. He’s also letting the company ignore many vital ecological protections on the books since at least the Reagan 1970s.

The Mothers/Friends lawsuit has major national implications. More than 90 US reactors now operate with an average age of 40. It’s a virtual certainty that all or most are dangerously embrittled. To support their work and to sign a petition demanding Diablo meet basic safety standards, go to

Will the federal courts now intervene to say they, too, must meet the same engineering standards Yankee Rowe failed to face three decades ago?

Stay tuned. And support both the Mothers for Peace and our Mother Earth.

Harvey Wasserman wrote THE PEOPLE’S SPIRAL OF US HISTORY: FROM JIGONSASEH TO SOLARTOPIA.  Most Mondays @ 2-4pm PT, he co-convenes the Green Grassroots Election Protection Zoom (www.electionprotection2024).  The Mothers for Peace ( could use your help in the struggle to shut the Diablo Canyon nukes.