As of the afternoon of Jan. 6, no U.S. power reactors were reporting any problems of note related to the “frigid extremes,” but ongoing monitoring will continue, the Nuclear Regulatory Commission (NRC) said.
The NRC’s regional offices in the Midwest and Northeast are keeping an eye on plant owners’ responses to the unusually low temperatures, NRC said in a Jan. 6 blog posting.
The NRC blog post said that the nuclear regulator is prepared to keep an eye on things during the so-called “polar vortex.” The National Weather Service said late Jan.6 that wind chill values from the northern Plains to the Central Appalachians could drop as low as negative -20 degrees F to -50 F.
“Plants in the affected areas have entered off-normal procedures that entail minimizing regular surveillance activities and increasing the frequency of checks and walk downs (visual evaluations) of equipment that could be impacted by the temperatures,” NRC said. NRC Resident Inspectors, who are assigned to specific sites, will continue to monitor the situation.
The inspectors use an “Adverse Weather Protection” inspection procedure to guide their assessments of whether plants are ready for extreme temperatures, including the bitter cold. Those reviews are typically done at the start of the season, NRC said.
NRC said it follows a 1998 protocol on cold weather problems and protective measures. Past winter problems at nuclear plants have included icing problems in cooling water systems; formation of an “ice plug” in a strainer backwash drain line and other issues.
“Licensees continue to find that icing and freezing from extreme cold weather conditions is a common-cause failure mechanism that can quickly affect a variety of systems unless mitigating actions are taken in a timely manner,” according to the 1998 NRC policy.