Event Notification Report for September 05, 1999
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
09/04/1999 - 09/05/1999
EVENT NUMBERS
36128
Power Reactor
Event Number: 36128
Facility: MILLSTONE
Region: 1 State: CT
Unit: [] [2] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: STEVE BRINKMAN
HQ OPS Officer: LEIGH TROCINE
Region: 1 State: CT
Unit: [] [2] []
RX Type: [1] GE-3,[2] CE,[3] W-4-LP
NRC Notified By: STEVE BRINKMAN
HQ OPS Officer: LEIGH TROCINE
Notification Date: 09/05/1999
Notification Time: 08:03 [ET]
Event Date: 09/05/1999
Event Time: 07:00 [EDT]
Last Update Date: 09/05/1999
Notification Time: 08:03 [ET]
Event Date: 09/05/1999
Event Time: 07:00 [EDT]
Last Update Date: 09/05/1999
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(1)(i)(A) - PLANT S/D REQD BY TS
10 CFR Section:
50.72(b)(1)(i)(A) - PLANT S/D REQD BY TS
Person (Organization):
JOHN ROGGE (R1)
JOHN ROGGE (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 85 | Power Operation | 84 | Power Operation |
TECH SPEC REQUIRED SHUTDOWN DUE TO HIGH ULTIMATE HEAT SINK TEMPERATURES
The unit's ultimate heat sink is Long Island Sound, and the technical specifications require the licensee to monitor service water temperatures every 6 hours. The licensee monitors these temperatures every 3 hours. The 0600 reading taken in a switchgear cooling room (the hottest point) indicated a service water temperature of 77°F, which was 2°F above the ultimate heat sink limit specified in the technical specifications. As a result, an investigation was initiated to determine whether or not this was an instrument problem. Temperatures measured at the intake structure (in the bay) remained in the low 70s. At 0700, the licensee determined that the high service water temperature readings were not an instrument problem, and a technical specification required shutdown was initiated at 0710. (With the ultimate heat sink inoperable, Technical Specification 3.7.11 required the unit to be placed in Hot Standby within 6 hours or Cold Shutdown within 30 hours.) Service water temperature was under 75°F at 0721, and the technical specification required shutdown was exited.
The licensee stated that the affect on the plant was negligible. Current weather conditions are hot and humid, and it is expected to cloud up this afternoon. The cause of the high service water temperature readings is currently under investigation.
Prior to discovery of this issue, the licensee was holding the unit at 85% power to clean mussels out of the circulating water bays.
The licensee notified the NRC resident inspector and the applicable state and local officials.
The unit's ultimate heat sink is Long Island Sound, and the technical specifications require the licensee to monitor service water temperatures every 6 hours. The licensee monitors these temperatures every 3 hours. The 0600 reading taken in a switchgear cooling room (the hottest point) indicated a service water temperature of 77°F, which was 2°F above the ultimate heat sink limit specified in the technical specifications. As a result, an investigation was initiated to determine whether or not this was an instrument problem. Temperatures measured at the intake structure (in the bay) remained in the low 70s. At 0700, the licensee determined that the high service water temperature readings were not an instrument problem, and a technical specification required shutdown was initiated at 0710. (With the ultimate heat sink inoperable, Technical Specification 3.7.11 required the unit to be placed in Hot Standby within 6 hours or Cold Shutdown within 30 hours.) Service water temperature was under 75°F at 0721, and the technical specification required shutdown was exited.
The licensee stated that the affect on the plant was negligible. Current weather conditions are hot and humid, and it is expected to cloud up this afternoon. The cause of the high service water temperature readings is currently under investigation.
Prior to discovery of this issue, the licensee was holding the unit at 85% power to clean mussels out of the circulating water bays.
The licensee notified the NRC resident inspector and the applicable state and local officials.