Event Notification Report for December 25, 2001
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
12/24/2001 - 12/25/2001
EVENT NUMBERS
38592
Power Reactor
Event Number: 38592
Facility: HATCH
Region: 2 State: GA
Unit: [] [2] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: STEVE HOWARD
HQ OPS Officer: JOHN MacKINNON
Region: 2 State: GA
Unit: [] [2] []
RX Type: [1] GE-4,[2] GE-4
NRC Notified By: STEVE HOWARD
HQ OPS Officer: JOHN MacKINNON
Notification Date: 12/25/2001
Notification Time: 20:40 [ET]
Event Date: 12/25/2001
Event Time: 18:19 [EST]
Last Update Date: 12/27/2001
Notification Time: 20:40 [ET]
Event Date: 12/25/2001
Event Time: 18:19 [EST]
Last Update Date: 12/27/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
LEONARD WERT (R2)
JOSEPH HOLONICH (IRO)
LEONARD WERT (R2)
JOSEPH HOLONICH (IRO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | A/R | Y | 100 | Power Operation | 0 | Hot Shutdown |
AUTOMATIC REACTOR SCRAM DUE TO 'A' RECIRCULATION PUMP SPEED UNEXPECTEDLY INCREASING
"At 18:19 Eastern on 12/25/01, Hatch Nuclear Plant Unit 2 reactor tripped. The cause is presently under investigation. Preliminary indications are that the 'A' Recirculation Pump speed increased. Reactor power increased causing the all four channels in the Neutron Monitoring System to trip. Group 2 Primary Containment isolation occurred. All group 2 isolated as expected. No other group isolations were required. RFPTs were used to maintain reactor water level, and Main Turbine Bypass valves maintained reactor pressure. No initiation signals required ECCS or RCIC to initiate."
On the automatic reactor scram, one control rod inserted to the 01 position and drifted to the 00 position. The swing Emergency Diesel Generator, 1B, is degraded but fully operable. The only other problem was that the Main Generator Output breakers did not automatically open but were manually opened from the control room. This problem has occurred before, and the control room operators are watching the output breakers.
The NRC resident inspector was notified of this event by the licensee.
***** UPDATE FROM GUY S. GRIFFIS TO LEIGH TROCINE AT 1217 ON 12/27/01 *****
This update was made to correct/clarify the cause of the automatic reactor scram from 100% power and to provide additional information.
It was initially reported that 'A' recirculation pump speed increased and caused all four channels in the neutron monitoring system to trip. However, further review determined that decreased main steam line 'B' flow caused the neutron monitoring system trip due to increased flux. Initial diagnostics indicate the 2B21-F028B main steam isolation valve as the failure.
The licensee's investigation is still ongoing. The licensee plans to provide additional detailed information in a Licensee Event Report.
NOTE: Cold Shutdown was achieved at 0255 on 12/27/01 in compliance with Technical Specification 3.6.1.3.e.
The licensee notified the NRC resident inspector. The NRC operations officer notified the R2DO (Boland) and IRO (Holonich).
"At 18:19 Eastern on 12/25/01, Hatch Nuclear Plant Unit 2 reactor tripped. The cause is presently under investigation. Preliminary indications are that the 'A' Recirculation Pump speed increased. Reactor power increased causing the all four channels in the Neutron Monitoring System to trip. Group 2 Primary Containment isolation occurred. All group 2 isolated as expected. No other group isolations were required. RFPTs were used to maintain reactor water level, and Main Turbine Bypass valves maintained reactor pressure. No initiation signals required ECCS or RCIC to initiate."
On the automatic reactor scram, one control rod inserted to the 01 position and drifted to the 00 position. The swing Emergency Diesel Generator, 1B, is degraded but fully operable. The only other problem was that the Main Generator Output breakers did not automatically open but were manually opened from the control room. This problem has occurred before, and the control room operators are watching the output breakers.
The NRC resident inspector was notified of this event by the licensee.
***** UPDATE FROM GUY S. GRIFFIS TO LEIGH TROCINE AT 1217 ON 12/27/01 *****
This update was made to correct/clarify the cause of the automatic reactor scram from 100% power and to provide additional information.
It was initially reported that 'A' recirculation pump speed increased and caused all four channels in the neutron monitoring system to trip. However, further review determined that decreased main steam line 'B' flow caused the neutron monitoring system trip due to increased flux. Initial diagnostics indicate the 2B21-F028B main steam isolation valve as the failure.
The licensee's investigation is still ongoing. The licensee plans to provide additional detailed information in a Licensee Event Report.
NOTE: Cold Shutdown was achieved at 0255 on 12/27/01 in compliance with Technical Specification 3.6.1.3.e.
The licensee notified the NRC resident inspector. The NRC operations officer notified the R2DO (Boland) and IRO (Holonich).