Event Notification Report for May 26, 2003
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
05/25/2003 - 05/26/2003
Power Reactor
Event Number: 39881
Facility: COOPER
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: WILLIAM B. GREEN
HQ OPS Officer: ERIC THOMAS
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: WILLIAM B. GREEN
HQ OPS Officer: ERIC THOMAS
Notification Date: 05/26/2003
Notification Time: 21:47 [ET]
Event Date: 05/26/2003
Event Time: 17:27 [CDT]
Last Update Date: 05/26/2003
Notification Time: 21:47 [ET]
Event Date: 05/26/2003
Event Time: 17:27 [CDT]
Last Update Date: 05/26/2003
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(iv)(A) - ECCS INJECTION 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)(A) - ECCS INJECTION 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Person (Organization):
TROY PRUETT (R4)
CYNTHIA CARPENTER (NRR)
TROY PRUETT (R4)
CYNTHIA CARPENTER (NRR)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | M/R | Y | 92 | Power Operation | 0 | Hot Shutdown |
MANUAL REACTOR SCRAM
This report is being made in accordance with 10CFR50.72 section (b)(2)(iv)(A), (b)(2)(iv)(B), and (b)(3)(iv)(A).
At 1727 on 5/26/03 a manual Reactor Scram was inserted from approximately 90 percent power due to high vibration on the main turbine. This action was taken in accordance with station procedures. The subsequent shrink caused reactor water level to lower to approximately -42 inches below instrument zero on the wide range level instruments. This level was low enough to cause the actuation of: Primary Containment Group Isolations 2, 3, and 6, High Pressure Coolant Injection (HPCI) system, Reactor Core Isolation Cooling (RCIC) system, and the Alternate Rod Insertion (ARI) system. The HPCI and RCIC systems injected for less than one minute. After Reactor water level recovered HPCI and Reactor Feed Pumps (RFP) were tripped prior to receiving the high water level trip of these pumps. The RCIC turbine tripped automatically on high reactor water level. A single RFP has been restarted and is currently providing feed water to the Reactor.
On the Scram all rods inserted and all systems appear to have functioned as designed. The Nebraska Public Power Load Dispatcher reports that the electrical grid is stable. The plant is currently in Mode 3 and is being cooled down to Mode 4.
When operators first noted the high turbine vibration, reactor power was lowered from 100 percent to 90 percent. The maximum specification for turbine vibration is 14 mils, and the operators noted a maximum indication of 12.5 mils prior to the scram. The cause of the excessive vibration is believed to be the number 5 bearing on the low pressure turbine. All Emergency Core Cooling Systems and Emergency Diesel Generators are operable.
The licensee notified the NRC Resident Inspector
This report is being made in accordance with 10CFR50.72 section (b)(2)(iv)(A), (b)(2)(iv)(B), and (b)(3)(iv)(A).
At 1727 on 5/26/03 a manual Reactor Scram was inserted from approximately 90 percent power due to high vibration on the main turbine. This action was taken in accordance with station procedures. The subsequent shrink caused reactor water level to lower to approximately -42 inches below instrument zero on the wide range level instruments. This level was low enough to cause the actuation of: Primary Containment Group Isolations 2, 3, and 6, High Pressure Coolant Injection (HPCI) system, Reactor Core Isolation Cooling (RCIC) system, and the Alternate Rod Insertion (ARI) system. The HPCI and RCIC systems injected for less than one minute. After Reactor water level recovered HPCI and Reactor Feed Pumps (RFP) were tripped prior to receiving the high water level trip of these pumps. The RCIC turbine tripped automatically on high reactor water level. A single RFP has been restarted and is currently providing feed water to the Reactor.
On the Scram all rods inserted and all systems appear to have functioned as designed. The Nebraska Public Power Load Dispatcher reports that the electrical grid is stable. The plant is currently in Mode 3 and is being cooled down to Mode 4.
When operators first noted the high turbine vibration, reactor power was lowered from 100 percent to 90 percent. The maximum specification for turbine vibration is 14 mils, and the operators noted a maximum indication of 12.5 mils prior to the scram. The cause of the excessive vibration is believed to be the number 5 bearing on the low pressure turbine. All Emergency Core Cooling Systems and Emergency Diesel Generators are operable.
The licensee notified the NRC Resident Inspector
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 39882
Facility: COOPER
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: WILLIAM GREEN
HQ OPS Officer: CHAUNCEY GOULD
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: WILLIAM GREEN
HQ OPS Officer: CHAUNCEY GOULD
Notification Date: 05/27/2003
Notification Time: 05:32 [ET]
Event Date: 05/26/2003
Event Time: 22:15 [CDT]
Last Update Date: 06/17/2003
Notification Time: 05:32 [ET]
Event Date: 05/26/2003
Event Time: 22:15 [CDT]
Last Update Date: 06/17/2003
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
10 CFR Section:
50.72(b)(3)(ii)(A) - DEGRADED CONDITION
Person (Organization):
TROY PRUETT (R4)
TROY PRUETT (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | N | 0 | Hot Shutdown | 0 | Hot Shutdown |
REACTOR COOLANT SYSTEM PRESSURE/TEMPERATURE TS LIMITS WERE EXCEEDED
At 2215 on 5/26/03 it was noted that Reactor Coolant System (RCS) Pressure/Temperature Limits for Non-Nuclear Heatup or Cooldown Following Nuclear Shutdown, Figure 3.4.9-1 of Technical Specifications, had been exceeded. This condition occurred due to Bottom Head Temperature being low due to a loss of forced circulation when Reactor Recirculation Pumps tripped during the manual scram reported in notification 39881. Reactor pressure was lowered and compliance with the curves has been reestablished. An analysis of this condition is required to be conducted in accordance with Technical Specification Required Action 3.4.9 A.2 to determine RCS acceptability for continued operation. The Reactor is required, as per LCO action statement, to be placed in Mode 4 by 1045 on 5/28/03.
The NRC Resident Inspector was notified.
* * * UPDATE 1614EDT ON 6/17/03 FROM ED McCUTCHEN TO S. SANDIN * * *
The licensee is retracting this event based on the following:
"Retraction of Event Notification 39882:
"On May 27, 2003, Cooper Nuclear Station reported that Reactor Coolant System (RCS) Pressure/Temperature (P/T) Limits for Non-Nuclear Heatup or Cooldown Following Nuclear Shutdown, Figure 3.4.9-1 of Technical Specifications, had been exceeded (Reference Event 39882). This condition occurred when Reactor Recirculation Pumps tripped during the manual scram reported in Event 39881. With the loss of forced circulation, stratification of the reactor coolant occurred and the resultant bottom head (Lower Plenum) temperatures were below the Technical Specification limit.
"The condition was reported in accordance with 10 CFR 50.72(b)(3)(ii)(A) as an event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.
"CNS was in Mode 3 (Hot Shutdown) when the P/T Limits were exceeded. Reactor pressure was lowered and compliance with the curve was reestablished. Per Limiting Condition for Operation (LCO) 3.4.9, Condition B, required Action B.2, the reactor was required to be in Mode 4 (Cold Shutdown) by 1045 on May 28, 2003. The reactor was placed in Mode 4 at 0844 on May 27, 2003.
"The Technical Specification required evaluation to determine that the RCS is acceptable for operation prior to entering Mode 2 (Startup) or Mode 3 has been completed. The evaluation determined that pressure and temperature data recorded during the condition demonstrate that the P/T Limits were maintained for the Upper Vessel/Steam Dome and Beltline Regions for the duration of the event.
"The recorded data for the Lower Plenum exceeded TS Figure 3.4.9-1 which is a composite curve established by superimposing limits derived from stress analyses of those portions of the reactor vessel and head that are the most restrictive. The analysis developed a bottom head (Lower Plenum) specific P/T curve using bottom head specific stresses and material properties. Considering this bottom head P/T curve, the evaluation results demonstrate that region specific P/T Limits for the Lower Plenum region of the vessel were maintained for the duration of the event.
"This event is bounded by the existing fatigue analysis for a loss of Feedwater Pumps. The transient has been captured in the fatigue monitoring program. The vessel usage factor of 1.0 has not been exceeded. Consequently, the reactor vessel maintains adequate structural integrity for continued operation.
"CNS is retracting this event based on the evaluation which demonstrates that the plant safety barrier (RCS) was not degraded."
The licensee informed the NRC resident inspector. Notified R4DO(Powers).
At 2215 on 5/26/03 it was noted that Reactor Coolant System (RCS) Pressure/Temperature Limits for Non-Nuclear Heatup or Cooldown Following Nuclear Shutdown, Figure 3.4.9-1 of Technical Specifications, had been exceeded. This condition occurred due to Bottom Head Temperature being low due to a loss of forced circulation when Reactor Recirculation Pumps tripped during the manual scram reported in notification 39881. Reactor pressure was lowered and compliance with the curves has been reestablished. An analysis of this condition is required to be conducted in accordance with Technical Specification Required Action 3.4.9 A.2 to determine RCS acceptability for continued operation. The Reactor is required, as per LCO action statement, to be placed in Mode 4 by 1045 on 5/28/03.
The NRC Resident Inspector was notified.
* * * UPDATE 1614EDT ON 6/17/03 FROM ED McCUTCHEN TO S. SANDIN * * *
The licensee is retracting this event based on the following:
"Retraction of Event Notification 39882:
"On May 27, 2003, Cooper Nuclear Station reported that Reactor Coolant System (RCS) Pressure/Temperature (P/T) Limits for Non-Nuclear Heatup or Cooldown Following Nuclear Shutdown, Figure 3.4.9-1 of Technical Specifications, had been exceeded (Reference Event 39882). This condition occurred when Reactor Recirculation Pumps tripped during the manual scram reported in Event 39881. With the loss of forced circulation, stratification of the reactor coolant occurred and the resultant bottom head (Lower Plenum) temperatures were below the Technical Specification limit.
"The condition was reported in accordance with 10 CFR 50.72(b)(3)(ii)(A) as an event or condition that results in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.
"CNS was in Mode 3 (Hot Shutdown) when the P/T Limits were exceeded. Reactor pressure was lowered and compliance with the curve was reestablished. Per Limiting Condition for Operation (LCO) 3.4.9, Condition B, required Action B.2, the reactor was required to be in Mode 4 (Cold Shutdown) by 1045 on May 28, 2003. The reactor was placed in Mode 4 at 0844 on May 27, 2003.
"The Technical Specification required evaluation to determine that the RCS is acceptable for operation prior to entering Mode 2 (Startup) or Mode 3 has been completed. The evaluation determined that pressure and temperature data recorded during the condition demonstrate that the P/T Limits were maintained for the Upper Vessel/Steam Dome and Beltline Regions for the duration of the event.
"The recorded data for the Lower Plenum exceeded TS Figure 3.4.9-1 which is a composite curve established by superimposing limits derived from stress analyses of those portions of the reactor vessel and head that are the most restrictive. The analysis developed a bottom head (Lower Plenum) specific P/T curve using bottom head specific stresses and material properties. Considering this bottom head P/T curve, the evaluation results demonstrate that region specific P/T Limits for the Lower Plenum region of the vessel were maintained for the duration of the event.
"This event is bounded by the existing fatigue analysis for a loss of Feedwater Pumps. The transient has been captured in the fatigue monitoring program. The vessel usage factor of 1.0 has not been exceeded. Consequently, the reactor vessel maintains adequate structural integrity for continued operation.
"CNS is retracting this event based on the evaluation which demonstrates that the plant safety barrier (RCS) was not degraded."
The licensee informed the NRC resident inspector. Notified R4DO(Powers).