Four items from this morning’s NRC Event Reports:
1. Late Saturday, operators were performing valve bypass testing on Unit 1 at the Monticello nuclear power plant in Minnesota, when the reactor scrammed and the Reactor Protective System activated on low water level. Following the scram, the water temperature in the discharge canal exceeded the plant’s Technical Specifications, and a report to the state of Minnesota and local agencies was made on the incident. Cause of the scram is still under investigation.
2. Sunday afternoon, during restart of Unit 3, operators at the Millstone nuclear power plant in Connecticut detected a loss of condensor vacuum and manually scrammed the reactor. The loss of vacuum was the resutl of the failure of the auxiliary steam boiler. The reactor is currently shutdown pending further investigation.
3. Another incident report from Monticello in Minnesota concerns a missing Local Power Range Monitor. The Range Monitor, which plant officials say somewhat vaguely had “greater than 1 gram of Uranium-233,” was moved to the spent fuel pool during a previous refueling operation. According to the Event Report: “There is no indication at this time that the detector has been inadvertently removed from the spent fuel pool and disposed of. The licensee believes that the detector is still in the pool and just needs to be located.”
4. And on Saturday, operators at the Palo Verde nuclear power plant in Arizona declared inoperable both trains of the Unit 2 Low Pressure Safety Injection System, following increasing pressure in four lines in the system. The reactor is currently in Hot Standby.