Event Notification Report for January 08, 2008
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
01/07/2008 - 01/08/2008
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 43885
Facility: PILGRIM
Region: 1 State: MA
Unit: [1] [] []
RX Type: [1] GE-3
NRC Notified By: FRANK CLIFFORD
HQ OPS Officer: STEVE SANDIN
Region: 1 State: MA
Unit: [1] [] []
RX Type: [1] GE-3
NRC Notified By: FRANK CLIFFORD
HQ OPS Officer: STEVE SANDIN
Notification Date: 01/08/2008
Notification Time: 16:47 [ET]
Event Date: 01/08/2008
Event Time: 10:40 [EST]
Last Update Date: 03/06/2008
Notification Time: 16:47 [ET]
Event Date: 01/08/2008
Event Time: 10:40 [EST]
Last Update Date: 03/06/2008
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
10 CFR Section:
50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Person (Organization):
ANTHONY DIMITRIADIS (R1)
ANTHONY DIMITRIADIS (R1)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
RCIC INOPERABLE DUE TO MIN FLOW VALVE INABILITY TO REPOSITION
"This report is being made in accordance with 10 CFR 50.72 (b) (3) (v) due to the Reactor Core Injection Cooling (RCIC) system being determined to be inoperable on 01/08/08 at 1040 EST. During a planned RCIC system outage, an instrument calibration surveillance identified a flow switch failure that would have prevented automatic closure of the pump minimum flow valve. Insufficient data is immediately available to assess the ability to achieve design basis flow rates with the minimum flow valve open. This event is an eight-hour notification. The RCIC instrument is currently under repair and will be completed prior to return to service.
"Plant is in a stable condition. Investigation is continuing.
"The resident NRC inspector has been notified of this event."
This event places them in a 14-day LCO per ACT-1-08-002. HPCI verified operable.
* * * UPDATE FROM RICHARD PROBASCO TO HOWIE CROUCH ON 03/06/08 @ 1656 EST * * *
BASIS FOR RETRACTION:
"Event Notification 43885 was conservatively made to ensure that the Eight-Hour Non Emergency reporting requirements of 10 CFR 50.72 were satisfied pending the evaluation of RCIC System operability.
"On 1/8/08, during performance of Attachment 5 to 8.E.13, 'RCIC System Instruments Calibration', RCIC flow switch FS-1360-7, contact number 2 failed to close as expected on increasing test pressure. This switch is expected to close while increasing test pressure between 13.7 to 14.3 inWC [inches of Water Column]. Contact number 2 closes when RCIC flow exceeds 100 gpm signaling [minimum] flow valve MO-1301-60 to close. Failure of the switch to close prevents automatic closure of the [minimum] flow valve on a system flow of 100 gpm increasing. Failure of the [minimum] flow valve to close during RCIC system operation would allow about 70 gpm to 170 gpm of RCIC pump discharge flow to go directly to the torus bypassing the reactor vessel.
"The switch was replaced and the flow switch was returned to service. The defective switch was evaluated and the cause of the failure was determined to be carbon buildup on the switch contacts.
"A functional failure review was performed to assess the impact of the flow switch failure on the RCIC System design basis functions. The RCIC System is required to automatically provide makeup water to the reactor vessel following vessel isolation. This review identifies that 400 gpm is adequate to meet reactor vessel makeup requirements. With the flow controller in 'AUTO' and the minimum flow valve open, the flow controller would increase turbine speed until the flow rate setpoint of 400 gpm is achieved. Based on evaluation of the RCIC System flow controller configuration, turbine speed limits, and hydraulic modeling, it was determined that the required 400 gpm flow rate could have been delivered under worst case conditions with a failed open minimum flow valve.
"These evaluations concluded that the RCIC System was capable of performing its intended safety functions during the time when FS-1360-7 failure prevented automatic closure of the pump minimum flow valve. The RCIC System would have started and supplied design basis flow to reactor vessel under design basis conditions. Thus there would have [been] no impact on nuclear safety. Therefore, this event was not reportable pursuant to 10 CFR 50.72(b)(3)(v).
"Event Number 43885, made on 01/08/2008, is being retracted."
The licensee will be notifying the NRC Resident Inspector. Notified R1DO (Caruso).
"This report is being made in accordance with 10 CFR 50.72 (b) (3) (v) due to the Reactor Core Injection Cooling (RCIC) system being determined to be inoperable on 01/08/08 at 1040 EST. During a planned RCIC system outage, an instrument calibration surveillance identified a flow switch failure that would have prevented automatic closure of the pump minimum flow valve. Insufficient data is immediately available to assess the ability to achieve design basis flow rates with the minimum flow valve open. This event is an eight-hour notification. The RCIC instrument is currently under repair and will be completed prior to return to service.
"Plant is in a stable condition. Investigation is continuing.
"The resident NRC inspector has been notified of this event."
This event places them in a 14-day LCO per ACT-1-08-002. HPCI verified operable.
* * * UPDATE FROM RICHARD PROBASCO TO HOWIE CROUCH ON 03/06/08 @ 1656 EST * * *
BASIS FOR RETRACTION:
"Event Notification 43885 was conservatively made to ensure that the Eight-Hour Non Emergency reporting requirements of 10 CFR 50.72 were satisfied pending the evaluation of RCIC System operability.
"On 1/8/08, during performance of Attachment 5 to 8.E.13, 'RCIC System Instruments Calibration', RCIC flow switch FS-1360-7, contact number 2 failed to close as expected on increasing test pressure. This switch is expected to close while increasing test pressure between 13.7 to 14.3 inWC [inches of Water Column]. Contact number 2 closes when RCIC flow exceeds 100 gpm signaling [minimum] flow valve MO-1301-60 to close. Failure of the switch to close prevents automatic closure of the [minimum] flow valve on a system flow of 100 gpm increasing. Failure of the [minimum] flow valve to close during RCIC system operation would allow about 70 gpm to 170 gpm of RCIC pump discharge flow to go directly to the torus bypassing the reactor vessel.
"The switch was replaced and the flow switch was returned to service. The defective switch was evaluated and the cause of the failure was determined to be carbon buildup on the switch contacts.
"A functional failure review was performed to assess the impact of the flow switch failure on the RCIC System design basis functions. The RCIC System is required to automatically provide makeup water to the reactor vessel following vessel isolation. This review identifies that 400 gpm is adequate to meet reactor vessel makeup requirements. With the flow controller in 'AUTO' and the minimum flow valve open, the flow controller would increase turbine speed until the flow rate setpoint of 400 gpm is achieved. Based on evaluation of the RCIC System flow controller configuration, turbine speed limits, and hydraulic modeling, it was determined that the required 400 gpm flow rate could have been delivered under worst case conditions with a failed open minimum flow valve.
"These evaluations concluded that the RCIC System was capable of performing its intended safety functions during the time when FS-1360-7 failure prevented automatic closure of the pump minimum flow valve. The RCIC System would have started and supplied design basis flow to reactor vessel under design basis conditions. Thus there would have [been] no impact on nuclear safety. Therefore, this event was not reportable pursuant to 10 CFR 50.72(b)(3)(v).
"Event Number 43885, made on 01/08/2008, is being retracted."
The licensee will be notifying the NRC Resident Inspector. Notified R1DO (Caruso).
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
!!!!! THIS EVENT HAS BEEN RETRACTED !!!!!
Power Reactor
Event Number: 43886
Facility: FT CALHOUN
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] CE
NRC Notified By: SCOTT LINDQUIST
HQ OPS Officer: JEFF ROTTON
Region: 4 State: NE
Unit: [1] [] []
RX Type: [1] CE
NRC Notified By: SCOTT LINDQUIST
HQ OPS Officer: JEFF ROTTON
Notification Date: 01/08/2008
Notification Time: 20:33 [ET]
Event Date: 01/08/2008
Event Time: 11:42 [CST]
Last Update Date: 02/20/2008
Notification Time: 20:33 [ET]
Event Date: 01/08/2008
Event Time: 11:42 [CST]
Last Update Date: 02/20/2008
Emergency Class: NON EMERGENCY
10 CFR Section:
50.72(b)(3)(v)(B) - POT RHR INOP
10 CFR Section:
50.72(b)(3)(v)(B) - POT RHR INOP
Person (Organization):
RUSSELL BYWATER (R4)
RUSSELL BYWATER (R4)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
POTENTIAL LOCA INJECTION FLOW RATE ISSUE
"At 11:42 CST, a condition report was initiated that questioned the specified flow path for simultaneous hot and cold leg injection following a large break loss of coolant accident (LOCA). When an unisolated LOCA event exists, simultaneous hot leg and cold leg injection should be implemented if the plant cannot be placed on shutdown cooling within six hours of the LOCA initiation and RCS pressure is less than 120 psia. The procedure is implemented at five and one-half hours to provide adequate time to align simultaneous hot/cold leg injection before the six hour time limit. Injecting to each side of the reactor vessel at an injection rate greater than 165 gpm, ensures that fluid from the reactor vessel (where the boric acid is being concentrated) flows out of the break regardless of the break location and is replenished with a dilute solution of borated water from the other side of the reactor vessel. The action is taken between 5.5 and 6 hours after the LOCA in order to ensure that the buildup of boric acid is terminated well before the potential for boric acid precipitation occurs which could restrict coolant flow through the core. Once the RCS is refilled, the boric acid is dispersed throughout the RCS via natural circulation. If entry into shutdown cooling system operation is anticipated before the 5.5 hour limit, then the realignment to hot/cold leg injection is unnecessary.
"The potential concern is associated with a charging line thermal relief valve CH-202 bypassing flow from hot leg injection and preventing the required flow rate needed to prevent boron precipitation from occurring. A minimum injection rate of 147 gpm to the cold legs and 159 gpm to the hot legs is required to prevent boric acid precipitation. Total hot leg injection flow is measured at FIA-236. Cold leg injection flow is the total of the four HPSI flow instruments, FI-313, FI-316, FI-319, and FI-322 with 50 gpm the minimum flow indication. A total cold leg injection flow of at least 200 gpm ensures at least 150 pm flow into the core, assuming 25% spillage out the break. This meets the required minimum of 147 gpm. It could not be determined through a review of the design basis documents and associated calculations what, if any, bypass flow is assumed through CH-202.
"Current procedural guidance in the emergency operating procedures is to align a high pressure safety injection pump to the charging header and provide hot leg injection from auxiliary pressurizer spray valves attached to the charging headers through the pressurizer and into the hot leg. The current procedural guidance does not isolate CH-202 and due to the location of flow instrument FIA-236, it cannot be guaranteed that all the flow through the charging system is being injected into the hot leg or being diverted through the normal charging line. As a result the potential existed which could have prevented the fulfillment of the safety function of a system needed to remove residual heat. Therefore this report is being made in reference to 10 CFR 50.72 (b) (3) (v) (B).
"Efforts are continuing to review design basis documents and calculations to determine if bypass flow was assumed past CH-202 when determining the minimum hot leg injection rate. As a compensatory measure, Operations management has restricted the use of hot and cold leg injection via the charging header until the design basis review confirms the adequacy of the current procedural guidance or the procedural guidance is revised. Pre-approved alternative methods will be utilized via the emergency operating procedures to perform simultaneous hot and cold leg injection if required."
No LCO condition exists. The licensee notified the NRC Resident Inspector.
* * UPDATE FROM ERICK MATZKE TO JOHN KNOKE AT 1619 EST ON 02/20/08 * *
"On January 8, 2008, (Event Number 43886) Fort Calhoun Station reported that there could be a potential reduction of injection flow to the hot leg during Long Term Core Cooling (LTCC) simultaneous hot and cold leg injection. The charging line thermal relief valve/check valve CH-202 could potentially divert flow from hot leg injection and reduce hot leg flow below the required flow rate needed to prevent boron precipitation from occurring. On January 8, 2008 it could not be determined through a review of design basis documents and associated calculations if bypass flow has been assumed through CH-202.
"Divergence of flow through CH-202 would result if a valve failure occurred. Assuming flow is diverted through CH-202, the operators would not realize that flow was going through the wrong flow path (cold leg) as their flow indication (FE-326) is located upstream of where the flow path to the hot leg and cold legs branch off. Therefore, there was nothing to alert the operator to isolate CH-202 or go to alternate hot leg injection. Previous procedural guidance was not adequate to address this condition. Current procedural guidance is adequate to address this condition as the procedures now require isolating CH-202 for LTCC.
"A reanalysis was performed to evaluate the required flow rate needed to prevent boron precipitation and ensure adequate LTCC. Calculations performed assumed full flow (failure) through CH-202. Under postulated design scenarios it was determined that adequate flow would have been provided to the hot legs during simultaneous hot and cold leg injection during LTCC. The calculations determined that under the evaluated scenarios, divergence of flow through CH-202 was acceptable, and that the requirements to maintain adequate flow to the core for LTCC decay heat removal and boron flushing would have been met.
"As a result of the analysis that were performed, it has been determined that the system was capable of performing its design function even under bypass flow conditions through CH-202. Therefore, this event is NOT reportable under 10 CFR 50.72( b) (3) (v) (B) as previously reported."
The licensee notified the NRC Resident Inspector. Notified R4 DO (Miller)
"At 11:42 CST, a condition report was initiated that questioned the specified flow path for simultaneous hot and cold leg injection following a large break loss of coolant accident (LOCA). When an unisolated LOCA event exists, simultaneous hot leg and cold leg injection should be implemented if the plant cannot be placed on shutdown cooling within six hours of the LOCA initiation and RCS pressure is less than 120 psia. The procedure is implemented at five and one-half hours to provide adequate time to align simultaneous hot/cold leg injection before the six hour time limit. Injecting to each side of the reactor vessel at an injection rate greater than 165 gpm, ensures that fluid from the reactor vessel (where the boric acid is being concentrated) flows out of the break regardless of the break location and is replenished with a dilute solution of borated water from the other side of the reactor vessel. The action is taken between 5.5 and 6 hours after the LOCA in order to ensure that the buildup of boric acid is terminated well before the potential for boric acid precipitation occurs which could restrict coolant flow through the core. Once the RCS is refilled, the boric acid is dispersed throughout the RCS via natural circulation. If entry into shutdown cooling system operation is anticipated before the 5.5 hour limit, then the realignment to hot/cold leg injection is unnecessary.
"The potential concern is associated with a charging line thermal relief valve CH-202 bypassing flow from hot leg injection and preventing the required flow rate needed to prevent boron precipitation from occurring. A minimum injection rate of 147 gpm to the cold legs and 159 gpm to the hot legs is required to prevent boric acid precipitation. Total hot leg injection flow is measured at FIA-236. Cold leg injection flow is the total of the four HPSI flow instruments, FI-313, FI-316, FI-319, and FI-322 with 50 gpm the minimum flow indication. A total cold leg injection flow of at least 200 gpm ensures at least 150 pm flow into the core, assuming 25% spillage out the break. This meets the required minimum of 147 gpm. It could not be determined through a review of the design basis documents and associated calculations what, if any, bypass flow is assumed through CH-202.
"Current procedural guidance in the emergency operating procedures is to align a high pressure safety injection pump to the charging header and provide hot leg injection from auxiliary pressurizer spray valves attached to the charging headers through the pressurizer and into the hot leg. The current procedural guidance does not isolate CH-202 and due to the location of flow instrument FIA-236, it cannot be guaranteed that all the flow through the charging system is being injected into the hot leg or being diverted through the normal charging line. As a result the potential existed which could have prevented the fulfillment of the safety function of a system needed to remove residual heat. Therefore this report is being made in reference to 10 CFR 50.72 (b) (3) (v) (B).
"Efforts are continuing to review design basis documents and calculations to determine if bypass flow was assumed past CH-202 when determining the minimum hot leg injection rate. As a compensatory measure, Operations management has restricted the use of hot and cold leg injection via the charging header until the design basis review confirms the adequacy of the current procedural guidance or the procedural guidance is revised. Pre-approved alternative methods will be utilized via the emergency operating procedures to perform simultaneous hot and cold leg injection if required."
No LCO condition exists. The licensee notified the NRC Resident Inspector.
* * UPDATE FROM ERICK MATZKE TO JOHN KNOKE AT 1619 EST ON 02/20/08 * *
"On January 8, 2008, (Event Number 43886) Fort Calhoun Station reported that there could be a potential reduction of injection flow to the hot leg during Long Term Core Cooling (LTCC) simultaneous hot and cold leg injection. The charging line thermal relief valve/check valve CH-202 could potentially divert flow from hot leg injection and reduce hot leg flow below the required flow rate needed to prevent boron precipitation from occurring. On January 8, 2008 it could not be determined through a review of design basis documents and associated calculations if bypass flow has been assumed through CH-202.
"Divergence of flow through CH-202 would result if a valve failure occurred. Assuming flow is diverted through CH-202, the operators would not realize that flow was going through the wrong flow path (cold leg) as their flow indication (FE-326) is located upstream of where the flow path to the hot leg and cold legs branch off. Therefore, there was nothing to alert the operator to isolate CH-202 or go to alternate hot leg injection. Previous procedural guidance was not adequate to address this condition. Current procedural guidance is adequate to address this condition as the procedures now require isolating CH-202 for LTCC.
"A reanalysis was performed to evaluate the required flow rate needed to prevent boron precipitation and ensure adequate LTCC. Calculations performed assumed full flow (failure) through CH-202. Under postulated design scenarios it was determined that adequate flow would have been provided to the hot legs during simultaneous hot and cold leg injection during LTCC. The calculations determined that under the evaluated scenarios, divergence of flow through CH-202 was acceptable, and that the requirements to maintain adequate flow to the core for LTCC decay heat removal and boron flushing would have been met.
"As a result of the analysis that were performed, it has been determined that the system was capable of performing its design function even under bypass flow conditions through CH-202. Therefore, this event is NOT reportable under 10 CFR 50.72( b) (3) (v) (B) as previously reported."
The licensee notified the NRC Resident Inspector. Notified R4 DO (Miller)