The U.S Inspector General (IG) issued a report this week with respect to the way that the Nuclear Regulatory Commission (NRC) handled the failure of an auxiliary feedwater system that required one of the nuclear reactors at the Diablo Canyon Nuclear Power Plant near San Luis Obispo on the coast of California to be shut down for eight days. The report stated that the IG found that the NRC had not properly inspected the feedwater system prior the shutdown.
     Dan Dorman is the NRC Executive Director for Operations. He said, “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. 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 response of the NRC to the IG report highlights multiple “factual errors and takes issue with several portions” in the IG report according to the NRC Office of Public Affairs. The NRC states that the leak in the auxiliary feedwater system did not cause the nuclear plant to shut down or compromise the plant’s safety as claimed by  the NRC. The NRC also said that the staff at Diablo Canyon found no evidence that auxiliary feedwater system pipe corrosion hidden under the metal jacketed insulation should have been located by NRC inspectors before the leak occurred.
      The NRC response states that “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. Corrosion under insulation, which caused this leak, is known to the industry and the NRC.”
      A spokesperson for Pacific Gas & Electric (PG&E) who operates Diablo Canyon claims that it identified the issue while the Unit 2 reactor was shut down for maintenance in 2020. Jim Jennings is a PG&E spokesman. He said, “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. 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.”
     The NRC said that it is confident in the effectiveness of its inspection programs. This is one of the many ways that it verifies nuclear power plant safety. It went on to say 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.
      Salud Carbajal is a Central Coast Congressman for California. He is reviewing the NRC response and a spokesperson for Carbajal said that the congressman intends to have further conversation with the NRC to learn more about the differences in conclusions between the two agencies. The spokesperson said, “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.”