2019 - 02 - 02 Mothers for Peace asks Governor Newsom to address embrittlement at Diablo Canyon

Mothers for Peace points out that there are serious questions about the safety and reliability of Unit One of Diablo Canyon nuclear plant. Embrittlement, cracking of the reactor vessel, and waste management require tests and close monitoring.

February 2, 2019 

TO:    Governor Newsom                 

RE:    Safety issues at Diablo Canyon nuclear plant 

Dear Governor Newsom:

San Luis Obispo Mothers for Peace (SLOMFP), a 501c3 nonprofit organization, has been the legal intervenor in matters regarding Diablo Canyon nuclear plant since 1973. We mailed a letter to you on December 26, 2018 regarding embrittlement of Diablo’s reactor vessel in Unit 1 (copy attached). We have not yet heard back from you about our concerns – and we have other issues to share as well.

Pacific Gas & Electric Company (PG&E) filed for bankruptcy on January 29, and that certainly complicates safe operation.

Here are several of the key issues:

EMBRITTLEMENT:  Since 2003 Diablo Canyon Unit One has a documented history of having a dangerously embrittled reactor vessel.  Because the internal components of all nuclear reactors are subjected to intense heat, pressure, and radiation, critical metals and welds can lose their resiliency.  Should a loss-of-coolant-accident necessitate emergency flooding of cooling water, embrittled components would shatter, leading to catastrophe.  The degree of embrittlement at Unit One can be easily and cheaply tested while the reactor is shut down for refueling.  

COMPONENT CRACKING:  All reactor pressure vessels and other key components can crack over time.  Unit One’s age makes it imperative that remotely controlled ultrasound devices be deployed to inspect the reactor internally, which can be done relatively easily and inexpensively. In 2013, PG&E applied for and received permission to delay testing for cracking, and so the ultrasound test has not been conducted since 2005.

WASTE MANAGEMENT: It is essential to conduct a full evaluation of waste management issues at Diablo. PG&E's contract with the Holtec Corporation for dry cask storage ends in December of 2019. PG&E can and should extend a Request for Proposal to seek a more robust and longer-lived dry cask storage option.

PG&E has recently proposed keeping the remaining spent fuel in the storage pools until 2032. This proposal is completely unacceptable because the tightly packed spent fuel pools are the plant components most vulnerable to terrorist attack. High-level radioactive waste would be better protected in improved dry cask storage.

Given PG&E’s pending bankruptcy, the company’s financial and managerial competence to operate the Diablo Canyon nuclear plant safely is in question. San Luis Obispo Mothers for Peace calls on the Governor, the legislature, and the California Public Utilities Commission (CPUC) to exercise responsibility on behalf of the safety and welfare of the people of California. PG&E must test the Unit One reactor vessel for embrittlement and cracking during the upcoming refueling outage.

If PG&E and the Nuclear Regulatory Commission fail to take the precautionary actions described above, then the CPUC must exercise its powers to determine the energy sources that are in the best interests of the people of the state. The CPUC should rule that PG&E may no longer charge the rate-payers for operations at the Diablo Canyon nuclear plant. Renewable sources, complemented by increasing energy efficiency and conservation, are coming on line at such a rate that there are days when California must PAY neighboring states to siphon off excess energy to avoid overloading the grid.

The people of California deserve reliable and safe energy resources.


San Luis Obispo Mothers for Peace

Board of Directors          


Liz Apfelberg

Elizabeth Brousse

Elaine Holder

Molly Johnson

Sherry Lewis

Linda Seeley

Jane Swanson

Jill ZamEk


CC:    California Senator Bill Monning

         California Assemblyman Jordan Cunningham

         CPUC President Picker

         U.S. Congressman Salud Carbajal