In its mid-year review of safety at American power reactors, the Nuclear Regulatory Commission reported that 91 of the 104 reactors in operation fell within the agency's highest safety rating. Six plants are slated to receive further inspections following up on items of low safety significance. And a further four plants will receive more intensive scrutiny following events that the agency feels represent a degraded safety cornerstone.
NRC 2011 Mid-Cycle Assessment: U.S Nuclear Plants Subject to Additional Oversight as of Sept. 6
NRC Action Matrix Column:
(One or two items of low safety significance)
The NRC issues yearly, biannual and quarterly assessments of plant safety, updating its Action Matrix continuously as operators address issues to inspectors' satisfaction. The 2010 annual assessment did not include any plants in the Multiple/Repetitive Degraded Cornerstone column. This time around, though, Browns Ferry and Fort Calhoun will receive what NRC describes as its "highest level of attention" following events in 2010 and the first half of this year.
The Omaha Public Power District's Fort Calhoun received a yellow finding in June, 2010, when the NRC determined its plan for sandbagging to protect the plant's intake structure and auxiliary building in the event of a flood failed to meet technical specifications. NRC also issued the plant a white finding in January after an M2 trip contactor failed from damaged caused by loose shading coils. The plant has put in place a corrective action plan, and an OPPD spokesman was quoted as saying much of the work to resolve the issues has been completed, although plant staff faced delays following flooding that shut down the reactor for much of the summer.
Browns Ferry unit 1, operated by the Tennessee Valley Authority, was issued a red finding by regulators last October after a broken valve was discovered in its emergency core cooling system - injection/spray subsystem. The NRC found the safety equipment was not fixed in a timely fashion. In response, an NRC official told Nashville Public Radio that a team of 14 inspectors will visit the site for two weeks this month, with additional inspections scheduled for the following three months.
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