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Investigation finds NRC inspectors failed to identify issue at Diablo Canyon Power Plant in 2020

Posted at 5:47 PM, Mar 28, 2022

The Office of the Inspector General (OIG) for the Nuclear Regulatory Commission (NRC) says NRC inspectors failed to identify a problem at the Diablo Canyon Nuclear Power Plant (DCNPP) in Avila Beach that led to a reactor shutdown in 2020.

In a report issued on March 25, the OIG said it launched an investigation after receiving multiple allegations regarding the NRC's oversight of the plant.

Those allegations reportedly involved oversight of the auxiliary feedwater (AFW) system, described as "a backup water supply that can be used to cool the reactor if normal feedwater is out of service."

According to the report, PG&E had to shut down one of Diablo Canyon's two reactors for eight days in July 2020 because of an AFW system failure. The OIG's investigation found that NRC inspectors failed to identify degraded piping insulation that led to a leak. They apparently did not inspect the area where the leak occurred even though an inspection report indicated that inspectors had conducted a complete walkdown of the system three months prior to the leak. In addition, the OIG says NRC staff did not spend the recommended number of hours inspecting the plant's AFW systems.

The OIG says the AFW system failure at Diablo Canyon has since been fixed, complies with regulatory requirements, "and DCNPP continues to operate safely."

"Safety is and always will be our most important responsibility at PG&E and Diablo Canyon, and the plant has an excellent safe operating record," said Suzanne Hosn, PG&E spokesperson. "We identified this issue while Unit 2 was shut down for maintenance in 2020, made the repairs and conducted thorough inspections before the unit was returned to service. Additionally, we performed similar inspections on Unit 1 and identified no further conditions requiring repair."

In a statement released Monday, Congressman Salud Carbajal, whose district includes the power plant, said he found the report to be "unsettling and unacceptable."

"The safety and wellbeing of the entire San Luis Obispo community relies on federal inspectors adhering to those safety protocols, and the negligence detailed in this report will erode the public trust in those who are tasked with keeping us safe," Carbajal said. "It is critically important that the NRC make a clear and convincing case to the Central Coast how it will hold their inspectors accountable for breaking protocol and how it intends to restore confidence in their operations at DCPP. In the coming days, I will be formally asking NRC leaders for specific details on why required inspections were not completed, what corrective actions will be taken, and what steps the NRC will take to enforce its regulations in the remaining time that DCPP is operational."

The OIG says it has forwarded its report to the NRC's executive leadership for review and response.

Click here to view the full report.