The Nuclear Regulatory Commission is beginning a special inspection this week at Duke Energy’s Catawba nuclear power plant to assess the circumstances surrounding the abnormal rotation of piston crankshaft bearings on the Unit 1 emergency diesel generators.
The plant is located near York, S.C., about 18 miles south of Charlotte, N.C.
During planned maintenance in early March, workers at the Catawba plant found that a connecting rod bearing on one of the two Unit 1 diesel generators had rotated from its normal position. A check of the other Unit 1 diesel generator led to the discovery of one of its bearings in a rotated position. Both of the bearings were replaced, but Duke Energy believes that the original bearings would have performed their function in the rotated position.
“While there was no event where the diesel generators were needed, they are extremely important should the plant lose offsite power,” said Victor McCree, NRC Region II Administrator. “Based on the need to gather more information and determine if there are generic issues that may apply to other plants, we felt a special inspection was warranted.”
The on-site inspectors for the special inspection are the senior resident inspector from the Harris nuclear plant and an inspector from the NRC’s Region II office in Atlanta. Another NRC expert from the agency’s headquarters in Rockville, Md., will not travel to the site but will assist in reviewing the nformation.
The team will review the circumstances surrounding the rotated bearings and the company’s actions after they were identified. It will also look at maintenance practices, assess any previous bearings issues at the plant and evaluate the company’s conclusions about whether the bearing would have operated in the abnormal position.
The on-site portion of the inspection will take several days. A report documenting the results should be issued within 45 days of the completion of the inspection.