30 Dec (NucNet): The US Nuclear Regulatory Commission has issued a white finding of low to moderate safety significance to the two-unit Diablo Canyon nuclear power station in California for failing to adequately maintain the emergency core cooling system at the plant.
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.
The NRC said that during a scheduled test conducted in May 2016, 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 NRC said the licensee, PG&E, has corrected the condition and changes have been made to maintenance procedures to prevent any recurrence.
The NRC evaluates regulatory performance at commercial nuclear plants with a color-coded process that categorises inspection findings as green, white, yellow or red in order of increasing safety significance.