Wed. Oct 4th, 2023
    Environmental Groups Petition for Immediate Shutdown of Diablo Canyon Nuclear Power Plant

    Mothers for Peace and Friends of the Earth, two environmental advocacy groups, have filed a joint petition calling for the immediate shutdown of Diablo Canyon Unit 1. The petition urges the Nuclear Regulatory Commission (NRC) to order tests and inspections of the power plant’s pressure vessel, which have been postponed for twenty years.

    The pressure vessel, which encases the highly radioactive reactor core, is a critical component of the reactor system. If the vessel were to fail, it could lead to a catastrophic meltdown. This risk is further heightened by the power plant’s proximity to earthquake faults. In the event of a major earthquake, a vessel failure could breach containment and amplify the potential consequences.

    Diablo Canyon’s operator, Pacific Gas and Electric Co. (PG&E), has repeatedly delayed essential metallurgical tests and ultrasound inspections on the pressure vessel over the past two decades. The last inspections took place in 2003-2005, but the results were deemed “not credible” by PG&E. They argued that data from similar reactors was sufficient to justify ongoing operation, despite indications of embrittlement.

    Dr. Digby Macdonald, a professor at UC Berkeley, has been retained by the advocacy groups to evaluate the status of Unit 1. Macdonald asserts that the test results from 2003-2005 were valid and should have prompted further inquiry instead of postponing future inspections. He criticizes PG&E’s reliance on data from other reactors, stating that each nuclear plant develops unique conditions and histories.

    Macdonald also highlights a prior warning to PG&E regarding defects in Unit 1, which were discovered during construction and called for additional testing. The failure to conduct surveillance and inspection of the pressure vessel, including beltline welds, has led to grave safety risks, according to Macdonald.

    The advocacy groups are appealing to the NRC commissioners to take charge of the situation, reverse the regulatory lapse, and ensure that the required tests and inspections are conducted immediately. They argue that Unit 1 must be shut down until the condition of the pressure vessel is thoroughly evaluated and justified through a public hearing.

    This petition is part of a broader legal strategy by the environmental groups to address safety concerns at Diablo Canyon. They aim to hold PG&E accountable for any cutting of corners that compromise safety, while urging the NRC to enhance oversight and transparency. The groups also raise concerns about the California State legislature’s decision to extend the plant’s operation without adequate safety assurances from the federal government agency responsible for regulatory oversight.


    – Mothers for Peace and Friends of the Earth joint petition to the Nuclear Regulatory Commission
    – Statement from Dr. Digby Macdonald, UC Berkeley Professor in Residence
    – Statements from Diane Curran, attorney for Mothers for Peace; Hallie Templeton, Legal Director for Friends of the Earth; and Linda Seeley, spokesperson for Mothers for Peace.