Federal regulators announced Monday they will conduct a special inspection at the Harris nuclear plant in North Carolina following equipment malfunctions during a planned shutdown last month.
At 5:15 a.m. on April 21, operators had just finished bringing the 900 megawatt Westinghouse pressurized water reactor to 0 percent power for a scheduled refueling outage. According to an NRC event report, two of the reactor’s main steam isolation valves then failed to close from the main control board during an operability test. One shut at 6:48 a.m. after the instrument air supply was isolated. The second closed nearly three hours later after its instrument air supply was isolated. Other equipment, including the turbine isolation valves, functioned as expected.
The valves in question are important for controlling steam releases under certain accident conditions, the NRC said in a release. While there was no immediate threat to public safety following the shutdown, the NRC will send four additional inspectors from its headquarters and its Atlanta office to study the event’s timeline, the valves’ performance history and the response by Progress Energy. The inspectors will issue a report in about 45 days.