Event Notification Report for March 03, 2001
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
03/02/2001 - 03/03/2001
Power Reactor
Event Number: 37804
Facility: SUMMER
Region: 2 State: SC
Unit: [1] [] []
RX Type: [1] W-3-LP
NRC Notified By: DAN GOLDSTON
HQ OPS Officer: LEIGH TROCINE
Region: 2 State: SC
Unit: [1] [] []
RX Type: [1] W-3-LP
NRC Notified By: DAN GOLDSTON
HQ OPS Officer: LEIGH TROCINE
Notification Date: 03/03/2001
Notification Time: 03:37 [ET]
Event Date: 03/03/2001
Event Time: 02:50 [EST]
Last Update Date: 03/03/2001
Notification Time: 03:37 [ET]
Event Date: 03/03/2001
Event Time: 02:50 [EST]
Last Update Date: 03/03/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(2)(i) - PLANT S/D REQD BY TS
10 CFR Section:
50.72(b)(2)(i) - PLANT S/D REQD BY TS
Person (Organization):
STEPHEN CAHILL (R2)
STEPHEN CAHILL (R2)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 12 | Power Operation | 11 | Power Operation |
TECHNICAL SPECIFICATION REQUIRED SHUTDOWN DUE TO FAILURE OF TWO FEEDWATER FLOW CHANNELS TO RESPOND DURING A PLANT STARTUP
The following text is a portion of a facsimile and E-mail received from the licensee:
"While performing a plant startup two channels of feedwater flow on [the] B Main Feed line failed to respond. Investigation showed that both transmitter's output was too low to support operability. These transmitters provide the feed flow signal that, in conjunction with low steam generator water level, provide a reactor trip. At 0225, [Technical Specification] 3.0.3 was entered, and power was reduced at 0250 to a nominal 11%."
"We expect to complete calibration/repairs on at least one of the transmitter loops prior to 0725. If at least one transmitter loop is not repaired, we must be in Hot Shutdown by 0925."
The licensee notified the NRC resident inspector.
The following text is a portion of a facsimile and E-mail received from the licensee:
"While performing a plant startup two channels of feedwater flow on [the] B Main Feed line failed to respond. Investigation showed that both transmitter's output was too low to support operability. These transmitters provide the feed flow signal that, in conjunction with low steam generator water level, provide a reactor trip. At 0225, [Technical Specification] 3.0.3 was entered, and power was reduced at 0250 to a nominal 11%."
"We expect to complete calibration/repairs on at least one of the transmitter loops prior to 0725. If at least one transmitter loop is not repaired, we must be in Hot Shutdown by 0925."
The licensee notified the NRC resident inspector.
Power Reactor
Event Number: 37805
Facility: COOPER
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: JOHN MYERS
HQ OPS Officer: STEVE SANDIN
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] GE-4
NRC Notified By: JOHN MYERS
HQ OPS Officer: STEVE SANDIN
Notification Date: 03/03/2001
Notification Time: 18:48 [ET]
Event Date: 03/03/2001
Event Time: 10:28 [CST]
Last Update Date: 03/13/2001
Notification Time: 18:48 [ET]
Event Date: 03/03/2001
Event Time: 10:28 [CST]
Last Update Date: 03/13/2001
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION 50.72(b)(3)(v)(B) - POT RHR INOP
10 CFR Section:
50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION 50.72(b)(3)(v)(B) - POT RHR INOP
Person (Organization):
LINDA HOWELL (R4)
LINDA HOWELL (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 |
VARIOUS SAFETY SYSTEM ACTUATIONS DURING A PLANNED SHUTDOWN
"While performing a planned shutdown for maintenance, an automatic scram and group isolations occurred due to low Reactor water level.
"The sequence of events was as follows: Initial manual scram was inserted at 09:42 CST to complete the shutdown as part of the plant shutdown procedure. Following the initial manual scram, 'B' Reactor Feed Pump (RFP) tripped on high water level. 'A' RFP was previously secured as part of the shutdown procedure. For undetermined reasons, 'B' RFP was unable to be returned to service. An attempt was made to start the 'A' RFP but efforts were stopped due to high vibrations received on 'A' RFP. Reactor Core Isolation Cooling (RCIC) was manually started to provide make up to the RPV [Reactor Pressure Vessel]. The subsequent shrink due to the relatively cool water being added caused water level to lower to the low level scram set point (level 3), and at 10:28 CST an automatic scram initiated, together with Group 2 (Primary Containment), Group 3 (Reactor Water Cleanup) and Group 6 (Secondary Containment) isolations. The Scram and automatic isolations functioned as designed, except Group 3 had been previously actuated due to high Non-regenerative Heat Exchanger temperature while initiating blowdown to the main condenser for level control. Level was restored to approximately 17 inches above the low level scram set point and the scram was reset. RCIC flow was lowered in anticipation of swell due to heating, and level again lowered. A manual scram was inserted approximately 4 inches prior to the low level scram set point. Level was recovered using RCIC, and, following resetting of the scram, water level was restored to the normal level, RCIC secured, and condensate system used to raise level to the shutdown level band. Level is presently being maintained using the condensate system.
"Investigation is on-going for the cause of being unable to restore 'B' RFP to service following the high level trip, and the reason for the high temperature isolation of RWCU [Reactor Water Cleanup].
"The Senior Resident Inspector has been notified."
The licensee is making preparations to place the unit in cold shutdown in the next 2-4 hours.
* * * UPDATE 1215EST ON 3/13/01 FROM DAVID VANDERKAMP TO S. SANDIN * * *
The licensee is providing the following clarification as an update:
"This is a follow-up report for event #37805 which was reported 3/3/2001 by Cooper Nuclear Station (CNS). The purpose of this follow-up is to clarify information provided in the initial eight hour report and to provide additional event information.
"The initial report described reactor water level anomalies during a normal planned shutdown for a scheduled mid-cycle outage. The initial report indicated that the 'B' reactor feedwater pump could not be reset and restarted. It was also reported that the 'A' reactor feedwater pump was unavailable. However, a more accurate characterization of the condition is that the 'A' reactor feedwater pump was started after being shutdown for some time. Due to the cold condition, vibration levels higher than expected were observed. The highest vibrations seen were well below the procedural limit requiring turbine trip. Operators made a conscious decision not to use the 'A' reactor feedwater pump other injection sources were available. The 'A' reactor feedwater pump was available and operators were aware of its availability, if needed.
"The shrink of water level that caused the automatic scram on low water level was initially attributed to the injection of cold water by RCIC. Subsequent evaluation has found that the shrink was due to a combination of the RCIC injection and that of steaming down due to normal pressure control via the Main Turbine Bypass Valves. Operators did not fully understand this interaction at the time of its occurrence.
"An additional condition not described in the initial report is concerned with a transient on the Reactor Equipment Cooling (REC) System. In an attempt to control high reactor water level, a blowdown was established via the Reactor Water Cleanup (RWCU) System. This blowdown was excessive and caused boiling in the REC system at the RWCU Non-Regenerative Heat Exchanger. This boiling resulted in a rapid expansion of the REC system volume with the excess spilling out the REC surge tank vent. An automatic isolation of the RWCU system due to high temperature terminated the condition. Subsequent collapse of the steam voids in the REC System caused the level in the REC surge tank to drop below the Technical Specifications allowed value for 5 minutes. During this time period the REC System was declared inoperable and then was returned to operable status after operators refilled the surge tank. The REC System continued to operate during this transient.
"The REC System is designed to provide cooling water for the removal of heat from equipment, such as the room coolers for the core spray pump rooms and HPCI pump room, required for a safe reactor shutdown following a Design Basis Accident or transient. With a loss of room cooling, the ability of the Emergency Core Cooling Systems to perform their required safety functions can no longer be assured. The investigation into the REC surge tank event continues, and the evidence to date indicates that the REC System transient was very short and REC remained available during the entire event. In addition, the reactor was shutdown during this transient. This potential loss of safety function is reportable as an eight hour report under 10CFR50.72(b)(3)(v)(B) pending a final evaluation. This is in addition to the eight hour report (Event #37805) previously made due to the valid actuation of the Reactor Protection System and Containment Isolation Systems. Both of these reports will be discussed in one Licensee Event Report (LER)."
The licensee will inform the NRC resident inspector. Notified R4DO(Johnson).
"While performing a planned shutdown for maintenance, an automatic scram and group isolations occurred due to low Reactor water level.
"The sequence of events was as follows: Initial manual scram was inserted at 09:42 CST to complete the shutdown as part of the plant shutdown procedure. Following the initial manual scram, 'B' Reactor Feed Pump (RFP) tripped on high water level. 'A' RFP was previously secured as part of the shutdown procedure. For undetermined reasons, 'B' RFP was unable to be returned to service. An attempt was made to start the 'A' RFP but efforts were stopped due to high vibrations received on 'A' RFP. Reactor Core Isolation Cooling (RCIC) was manually started to provide make up to the RPV [Reactor Pressure Vessel]. The subsequent shrink due to the relatively cool water being added caused water level to lower to the low level scram set point (level 3), and at 10:28 CST an automatic scram initiated, together with Group 2 (Primary Containment), Group 3 (Reactor Water Cleanup) and Group 6 (Secondary Containment) isolations. The Scram and automatic isolations functioned as designed, except Group 3 had been previously actuated due to high Non-regenerative Heat Exchanger temperature while initiating blowdown to the main condenser for level control. Level was restored to approximately 17 inches above the low level scram set point and the scram was reset. RCIC flow was lowered in anticipation of swell due to heating, and level again lowered. A manual scram was inserted approximately 4 inches prior to the low level scram set point. Level was recovered using RCIC, and, following resetting of the scram, water level was restored to the normal level, RCIC secured, and condensate system used to raise level to the shutdown level band. Level is presently being maintained using the condensate system.
"Investigation is on-going for the cause of being unable to restore 'B' RFP to service following the high level trip, and the reason for the high temperature isolation of RWCU [Reactor Water Cleanup].
"The Senior Resident Inspector has been notified."
The licensee is making preparations to place the unit in cold shutdown in the next 2-4 hours.
* * * UPDATE 1215EST ON 3/13/01 FROM DAVID VANDERKAMP TO S. SANDIN * * *
The licensee is providing the following clarification as an update:
"This is a follow-up report for event #37805 which was reported 3/3/2001 by Cooper Nuclear Station (CNS). The purpose of this follow-up is to clarify information provided in the initial eight hour report and to provide additional event information.
"The initial report described reactor water level anomalies during a normal planned shutdown for a scheduled mid-cycle outage. The initial report indicated that the 'B' reactor feedwater pump could not be reset and restarted. It was also reported that the 'A' reactor feedwater pump was unavailable. However, a more accurate characterization of the condition is that the 'A' reactor feedwater pump was started after being shutdown for some time. Due to the cold condition, vibration levels higher than expected were observed. The highest vibrations seen were well below the procedural limit requiring turbine trip. Operators made a conscious decision not to use the 'A' reactor feedwater pump other injection sources were available. The 'A' reactor feedwater pump was available and operators were aware of its availability, if needed.
"The shrink of water level that caused the automatic scram on low water level was initially attributed to the injection of cold water by RCIC. Subsequent evaluation has found that the shrink was due to a combination of the RCIC injection and that of steaming down due to normal pressure control via the Main Turbine Bypass Valves. Operators did not fully understand this interaction at the time of its occurrence.
"An additional condition not described in the initial report is concerned with a transient on the Reactor Equipment Cooling (REC) System. In an attempt to control high reactor water level, a blowdown was established via the Reactor Water Cleanup (RWCU) System. This blowdown was excessive and caused boiling in the REC system at the RWCU Non-Regenerative Heat Exchanger. This boiling resulted in a rapid expansion of the REC system volume with the excess spilling out the REC surge tank vent. An automatic isolation of the RWCU system due to high temperature terminated the condition. Subsequent collapse of the steam voids in the REC System caused the level in the REC surge tank to drop below the Technical Specifications allowed value for 5 minutes. During this time period the REC System was declared inoperable and then was returned to operable status after operators refilled the surge tank. The REC System continued to operate during this transient.
"The REC System is designed to provide cooling water for the removal of heat from equipment, such as the room coolers for the core spray pump rooms and HPCI pump room, required for a safe reactor shutdown following a Design Basis Accident or transient. With a loss of room cooling, the ability of the Emergency Core Cooling Systems to perform their required safety functions can no longer be assured. The investigation into the REC surge tank event continues, and the evidence to date indicates that the REC System transient was very short and REC remained available during the entire event. In addition, the reactor was shutdown during this transient. This potential loss of safety function is reportable as an eight hour report under 10CFR50.72(b)(3)(v)(B) pending a final evaluation. This is in addition to the eight hour report (Event #37805) previously made due to the valid actuation of the Reactor Protection System and Containment Isolation Systems. Both of these reports will be discussed in one Licensee Event Report (LER)."
The licensee will inform the NRC resident inspector. Notified R4DO(Johnson).