The Nuclear Regulatory Commission on Dec. 29 issued a white inspection finding at the Diablo Canyon Power Plant, confirming that operator Pacific Gas & Electric (PG&E) failed to “adequately maintain the (plant’s) emergency core cooling system.”
Located about 12 miles southwest of San Luis Obispo, Diablo Canyon is the last operating nuclear plant in California and is scheduled to close by 2025. A white inspection finding represents a “low to moderate” safety issue.
According to the NRC, Diablo Canyon personnel discovered during a scheduled test in May that one of the plant’s Unit 2 emergency cooling systems was inoperable for a lengthy period of time, potentially dating as far back as October 2014. The reactor unit did have a backup cooling system available, as each reactor at Diablo Canyon is equipped with two emergency cooling systems in case of emergencies.
Following PG&E’s discovery in May, the NRC completed an inspection at the plant on Sept. 12 and a regulatory conference with the company on Nov. 15. The regulator said PG&E has since corrected the issue and implemented maintenance changes to ensure the problem doesn’t recur. The regulator will inspect the plant at a later, unspecified date to ensure the company has properly addressed the matter.
PG&E spokeswoman Blair Jones said by email Wednesday the company is considering appealing the NRC’s ruling, though she did not say when it might reach a decision. If the white finding is finalized, it could mean increased NRC oversight and inspections at the plant. Jones said management believes that in the unlikely event that the system would be needed, the plant’s professional operators would “have successfully responded to ensure the equipment met its function,” noting that redundant cooling sources were also available.
“We are absolutely committed to the highest safety standards,” Jones wrote. “This relentless focus on safety led us to discover this issue and make immediate repairs. We believe it is not reflective of current plant performance.”
PG&E announced in June that Diablo Canyon’s two units will shut down by 2024-25, when their operating licenses expire, as the company shifts toward “greenhouse-gas-free resources.” The utility said California’s shifting energy policies significantly reduce the need for electricity output at Diablo Canyon, citing the state’s goal of increasing its renewable portfolio standard — the amount of energy produced by renewable sources — to 50 percent by 2030. The Diablo Canyon decommissioning is expected to cost about $3.8 billion, according to a study PG&E delivered in March.
