RALEIGH, N.C. – Federal regulators said Wednesday that they are conducting a special inspection of a nuclear power plant outside North Carolina's capital city that was forced to shut down last week after operators discovered corrosion and cracking in the reactor vessel's covering.
Two Nuclear Regulatory Commission specialist inspectors will join the on-site NRC inspectors "to assess the circumstances surrounding the discovery," the agency said in a news release.
Plant operator Duke Energy said last week it found a quarter-inch mark of corrosion and cracking in the covering of the reactor vessel, which contains heat produced by the nuclear core's energy. The crack did not penetrate the vessel head and there was no evidence of radiation leakage, the NRC and Duke Energy said.
"There was no immediate threat to the public or plant workers, but because the discovery is on the vessel head and was not seen in the original review, we are sending specialists from our Atlanta office to further evaluate the issue," said Victor McCree, the NRC's Southeast regional manager. "The special inspection team will work to analyze and understand all the details."
Duke Energy has started the repair process, the agency said. The company expects to have the reactor back in production within weeks, Duke Energy said in a filing with the U.S. Securities and Exchange Commission last week.
Charlotte-based Duke Energy took over the Harris plant after it acquired Raleigh-based Progress Energy last year, which made it the country's largest electric company. The utility is cooperating with the NRC inspection, Duke Energy spokeswoman Rita Sipe said in an email.
"We have a team that is also performing our own evaluation to determine why this was not identified in previous reviews," Sipe said.
The shutdown came as plant operators prepared for an upcoming refueling outage by reviewing results from ultrasonic testing gathered during a refueling outage last spring.
The on-site portion of the inspection at the southern Wake County nuclear plant is expected to take about a week and a half, with a report to be issued within 45 days after the inspection is completed, the NRC said.
The inspection team will review Duke Energy's actions leading up to the discovery of the problem, examine the previous ultrasonic testing records, evaluate the company's repair plans, and decide whether the discovery highlights any broader issues that other nuclear plant operators should be aware of, the regulatory agency said.
Progress Energy was cited last year for two safety violations at the Harris plant considered to be of low to moderate significance, which an NRC spokesman said last week has since been corrected. Regulators found problems with ventilation systems that would be needed if there were a nuclear emergency.