NRC cites Diablo Canyon over emergency core cooling system

The Nuclear Regulatory Commission (NRC) has cited the PG&E (NYSE:PCG) Diablo Canyon nuclear plant in California with a white finding of low to moderate safety significance for failing to adequately maintain the emergency core cooling system.

The NRC announced the white finding against the two-reactor plant in in San Luis Obispo, California in a Dec. 29 news release.

In 2016 the company announced that it would not seek 20-year license renewals for the two reactor units at California’s remaining nuclear station, Diablo Canyon. The two pressurized water reactor (PWR) units, which together have a capacity of 2,200 MW, will both be retired by the end of 2025.

Each reactor at Diablo Canyon is equipped with two emergency core cooling systems that are used to provide cooling water to a reactor under certain accident conditions. During a scheduled test conducted in May, workers discovered that a maintenance problem had rendered one of the Unit 2 emergency core cooling systems inoperable for an extended period of time, beginning as early as October 2014.

A second emergency core cooling system was available if needed. The licensee has corrected the condition and changes have been made to maintenance procedures to prevent recurrence. The issue is described in an NRC inspection report. NRC staff held a regulatory conference with representatives from Pacific Gas & Electric on Nov. 15, in Arlington, Texas, to discuss the issue.

The finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the NRC enforcement policy.

The NRC evaluates regulatory performance at commercial nuclear plants with a color-coded process that categorizes inspection findings as green, white, yellow or red in order of increasing safety significance.

The NRC has determined that this inspection finding has low to moderate (white) safety significance. The NRC will conduct an inspection to verify the licensee’s corrective actions have been properly implemented.

About Wayne Barber 4201 Articles
Wayne Barber, Chief Analyst for the GenerationHub, has been covering power generation, energy and natural resources issues at national publications for more than 20 years. Prior to joining PennWell he was editor of Generation Markets Week at SNL Financial for nine years. He has also worked as a business journalist at both McGraw-Hill and Financial Times Energy. Wayne also worked as a newspaper reporter for several years. During his career has visited nuclear reactors and coal mines as well as coal and natural gas power plants. Wayne can be reached at