NRC to hold discuss proposed violation at Diablo Canyon

The Nuclear Regulatory Commission will meet with officials from the Pacific Gas & Electric Company on Nov. 15, to discuss a preliminary finding regarding the licensee’s failure to adequately maintain the emergency core cooling system at the Diablo Canyon nuclear power plant in San Luis Obispo, Calif.

The public meeting, scheduled for 12:30 p.m., will be held at the NRC’s Region IV office at 1600 E. Lamar Blvd., Arlington, Texas. NRC officials will answer questions from the public following the business portion of the meeting. A telephone bridge will be available for the meeting by calling 888-790-5880 and entering passcode 4630080.


Each reactor at Diablo Canyon is equipped with two emergency core cooling systems that are used to provide cooling water to a reactor under some 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 had it been 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.

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 preliminarily determined that the inspection finding has low to moderate (white) safety significance, which may require additional inspections, regulatory actions and oversight.

No decision on the final safety significance of the finding or any additional NRC actions are expected to be made at the conference. That decision will be announced at a later time and documented in an NRC inspection report.