U.S. Nuclear Regulatory Commission finds errors in Inspector General’s report on Diablo Canyon
SAN LUIS OBISPO COUNTY, Calif. – The U.S. Nuclear Regulatory Commission (NRC) released a response on Tuesday to the Office of the Inspector General's March report finding that the NRC failed to properly inspect an important component at the Diablo Canyon Nuclear Power Plant, saying that the initial investigation was faulty.
“After reviewing the Inspector General’s event inquiry, our technical staff determined that the Reactor Oversight Program and its associated inspection program continue to provide reasonable assurance of adequate protection of public health and safety,” said NRC Executive Director for Operations Dan Dorman.
“Resident inspectors are vital to the NRC safety mission. I have full confidence in the qualification, abilities, and professionalism of the inspectors involved in this event inquiry as well as all of our inspectors.”
The original report by the Inspector General alleged that, among other things, the plant's auxiliary feedwater system failure that required one nuclear reactor to shut down for eight days was not properly inspected by the NRC prior to the shutdown.
The NRC's response highlights multiple "factual errors and takes issue with several portions" of the Inspector General's report, according to the NRC Office of Public Affairs.
The NRC's response claims that the leak in the auxiliary feedwater system did not cause the nuclear plant to shut down or compromise the plant's safety as stated by the Inspector General.
It also states that staff found no evidence that the auxiliary feedwater pipe corrosion hidden under the metal jacketed insulation should have been located by NRC inspectors before the leak occurred.
"The resident inspectors then assigned to Diablo Canyon followed appropriate guidance during their inspection of the system and regional and headquarters management appropriately determined that the leak had very low safety significance," the NRC's response states.
"Corrosion under insulation, which caused this leak, is known to the industry and the NRC."
A spokesman from PG&E, who operates the plant, said that it identified this issue while Unit 2 was shut down for maintenance in 2020.
"(PG&E) 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," PG&E spokesman Jim Jennings said in a statement to News Channel 3-12.
"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," Jennings added.
The NRC said that it remains confident in the effectiveness of its inspection programs, which is one of the many ways it verifies nuclear power plant safety.
It said that other methods include the Reactor Oversight Program performance indicators, robust design margins for every plant, and operator and training requirements to enable plant operators to respond to equipment malfunctions, among other methods.
Central Coast Congressman Salud Carbajal was still reviewing the NRC's response on Tuesday afternoon and a spokesperson for Carbajal said that the congressman intends to have further conversations with the NRC to learn more about the difference in conclusions between the two bodies.
"The congressman believes it is of the utmost importance to understand why there are conflicting conclusions in these documents and what can be done to communicate those reasons clearly to Central Coast communities," the spokesperson said.
