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{{#Wiki_filter:Dominion Nuclear Connecticut, Inc.Rope Ferry Rd., Waterford, CT 06385 JWEEE.E..W.. | {{#Wiki_filter:Dominion Nuclear Connecticut, Inc. | ||
Mailing Address: P.O. Box 128 JAN 28 2014 Waterford, CT 06385 don .conm U.S. Nuclear Regulatory Commission Serial No. 14-043 Attention: | Rope Ferry Rd., Waterford, CT 06385 JWEEE.E..W.. | ||
Document Control Desk MPS Lic/MLC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.MILLSTONE POWER STATION UNIT 3 REQUEST FOR ENFORCEMENT DISCRETION FROM TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM In a teleconference call on January 26, 2014, Dominion Nuclear Connecticut, Inc.(DNC) informed the NRC staff of the need for a notice of enforcement discretion (NOED) from the requirements of Millstone Power Station Unit 3 (MPS3) Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater System, which states, "At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE," with ACTION c. stating for Inoperable Equipment, "One auxiliary feedwater pump in MODE 1, 2, or 3 for reasons other than a. or b. above. Restore the auxiliary feedwater pump to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." This NOED request (regular) is being made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension period of 36 hours prior to initiating shutdown of the unit.The Facility Safety Review Committee has reviewed and concurs with this request.This NOED request was verbally approved by the NRC on January 26, 2014 at approximately 1245 hours. Per NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC is required to submit a written request for the NOED within two working days of the oral request for a regular NOED. This letter and its attachments provide the information documenting DNC's request.The turbine driven auxiliary feedwater pump was restored to OPERABLE status at 0505 on January 27, 2014. The compensatory actions to review existing transient combustible permits, existing ignition sources, racking breakers and perform area walkdowns for the affected fire areas, and to brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas were completed at 1800 January 26, 2014.There are no regulatory commitments contained in this letter.bP-Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Page 2 of 2 If you should have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.Sincel S. E. Scace Site Vice President | Mailing Address: P.O. Box 128 JAN 28 2014 Waterford, CT 06385 don .conm U.S. Nuclear Regulatory Commission Serial No. 14-043 Attention: Document Control Desk MPS Lic/MLC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC. | ||
-Millstone | MILLSTONE POWER STATION UNIT 3 REQUEST FOR ENFORCEMENT DISCRETION FROM TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM In a teleconference call on January 26, 2014, Dominion Nuclear Connecticut, Inc. | ||
(DNC) informed the NRC staff of the need for a notice of enforcement discretion (NOED) from the requirements of Millstone Power Station Unit 3 (MPS3) Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater System, which states, "At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE," with ACTION c. stating for Inoperable Equipment, "One auxiliary feedwater pump in MODE 1, 2, or 3 for reasons other than a. or b. above. Restore the auxiliary feedwater pump to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." | |||
This NOED request (regular) is being made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension period of 36 hours prior to initiating shutdown of the unit. | |||
The Facility Safety Review Committee has reviewed and concurs with this request. | |||
This NOED request was verbally approved by the NRC on January 26, 2014 at approximately 1245 hours. Per NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC is required to submit a written request for the NOED within two working days of the oral request for a regular NOED. This letter and its attachments provide the information documenting DNC's request. | |||
The turbine driven auxiliary feedwater pump was restored to OPERABLE status at 0505 on January 27, 2014. The compensatory actions to review existing transient combustible permits, existing ignition sources, racking breakers and perform area walkdowns for the affected fire areas, and to brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas were completed at 1800 January 26, 2014. | |||
There are no regulatory commitments contained in this letter. | |||
bP- | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Page 2 of 2 If you should have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687. | |||
Sincel S. E. Scace Site Vice President - Millstone | |||
==Attachment:== | ==Attachment:== | ||
: 1. Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2 -Auxiliary Feedwater System cc: U.S. Nuclear Regulatory Commission Region 1 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager -Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08-C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Serial No. 14-043 Docket No. 50-423 ATTACHMENT 1 REQUEST FOR ENFORCEMENT DISCRETION FROM THE REQUIREMENTS OF TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC. (DNC) | : 1. Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2 - Auxiliary Feedwater System cc: U.S. Nuclear Regulatory Commission Region 1 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08-C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1 Page 1 of 18 Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2, Auxiliary Feedwater System Introduction Dominion Nuclear Connecticut, Inc. (DNC) hereby requests the NRC staff to exercise discretion not to enforce compliance with the Millstone Power Station Unit 3 (MPS3)Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater (AFW) System.Discussion of the Requirements for which Enforcement Discretion is Requested Consistent with NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC herein provides a supporting description and justification for issuance of the requested notice of enforcement discretion (NOED).a. Specifically address what type of NOED is being requested (regular or natural event), which of the NOED criteria for appropriate plant conditions specified in subsection 03.03 of this guidance is satisfied, and how the licensee satisfied those criteria. (also reference subsection 06.02 of this IMC)A regular NOED is being requested in accordance with NOED Criterion 03.03(b) of NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion". | |||
Criterion 03.03(b) involves the following condition: "an unnecessary down-power or the shutdown of a reactor without a corresponding health and safety benefit." This enforcement discretion is requested until 0150 hours on January 28, 2014, for TS 3.7.1.2 -Auxiliary Feedwater System.The request for enforcement discretion was made to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of 36 hours to the existing allowed outage time (AOT) of 72 hours for an inoperable auxiliary feedwater pump. The 36 hour duration is needed to support repair and testing activities which are in progress. | Serial No. 14-043 Docket No. 50-423 ATTACHMENT 1 REQUEST FOR ENFORCEMENT DISCRETION FROM THE REQUIREMENTS OF TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC. (DNC) | ||
See detailed information in section'e' below: b. Provide a description of the TS or other license conditions that will be violated, and, if applicable, state that adhering to the license would cause an unnecessary transient. | |||
This description shall include the time remaining before the TS or license condition will be violated. | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1 Page 1 of 18 Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2, Auxiliary Feedwater System Introduction Dominion Nuclear Connecticut, Inc. (DNC) hereby requests the NRC staff to exercise discretion not to enforce compliance with the Millstone Power Station Unit 3 (MPS3) | ||
When a "regular" NOED is requested, the licensee must show that granting the NOED request would avoid an unnecessary transient. | Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater (AFW) System. | ||
The TS that will be violated is MPS3 Technical Specification (TS) 3.7.1.2 -Auxiliary Feedwater System. The TS requires: | Discussion of the Requirements for which Enforcement Discretion is Requested Consistent with NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC herein provides a supporting description and justification for issuance of the requested notice of enforcement discretion (NOED). | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 2 of 18"At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE with: a. Two motor-driven auxiliary feedwater pumps, each capable of being powered from separate emergency busses, and b. One steam turbine-driven auxiliary feedwater pump capable of being powered from an OPERABLE steam supply system." If one auxiliary feedwater pump in MODE 1, 2, or 3, for reasons other than in ACTIONs a. or b. is inoperable, ACTION c. of this TS requires the auxiliary feedwater pump be restored to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours.The basis of the TS requirement is to ensure a makeup water supply to the steam generators (SGs) is available to support decay heat removal from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply, assuming the worst case single failure. The AFW system consists of two motor driven AFW pumps and one steam turbine driven AFW pump. Each motor driven AFW pump provides at least 50% of the AFW flow capacity assumed in the accident analysis. | : a. Specifically address what type of NOED is being requested (regular or natural event), which of the NOED criteria for appropriate plant conditions specified in subsection 03.03 of this guidance is satisfied, and how the licensee satisfied those criteria. (also reference subsection 06.02 of this IMC) | ||
After reactor shutdown, decay heat eventually decreases so that one motor driven AFW pump can provide sufficient SG makeup flow. The steam driven AFW pump has a rated capacity approximately double that of a motor driven AFW pump and is thus defined as a 100%capacity pump.Given the worst case single failure, the AFW System is designed to mitigate the consequences of numerous design basis accidents, including Feedwater Line Break, Loss of Normal Feedwater, Steam Generator Tube Rupture, Main Steam Line Break, and Small Break Loss of Coolant Accident.In addition, given the worst case failure, the AFW is designed to supply sufficient makeup water to replace SG inventory loss as the RCS is cooled to less than 350°F at which point the Residual Heat Removal System may be placed into operation. | A regular NOED is being requested in accordance with NOED Criterion 03.03(b) of NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion". Criterion 03.03(b) involves the following condition: "an unnecessary down-power or the shutdown of a reactor without a corresponding health and safety benefit." | ||
Enforcement discretion is requested to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of 36 hours to the AOT. The additional 36 hour duration is needed to support repair and testing activities which are in progress.At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was GREEN. MPS3 was in TS Action statement 3.7.1.2.c., Auxiliary Feedwater System -One auxiliary feedwater pump inoperable which states: "Restore the auxiliary feedwater pump to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." | This enforcement discretion is requested until 0150 hours on January 28, 2014, for TS 3.7.1.2 - Auxiliary Feedwater System. | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 3 of 18 c. Provide a description of the circumstances, including as a minimum: likely causes; the need for prompt action; the action taken to avoid the need for a NOED; and any relevant historical events. The historical events must include as a minimum, any other similar events at the plant, the last maintenance performed on the equipment or similar equipment, any outstanding amendment or TS change requests related to the NOED, and the last NOED request from the plant.On January 23, 2014 the MPS3 Turbine Driven Auxiliary Feedwater (TDAFW) pump tripped during the performance of surveillance procedure SP3622.3 as documented in condition report CR537862. | The request for enforcement discretion was made to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of 36 hours to the existing allowed outage time (AOT) of 72 hours for an inoperable auxiliary feedwater pump. The 36 hour duration is needed to support repair and testing activities which are in progress. See detailed information in section | ||
The likely cause of this test failure was insufficient force being applied to the TDAFW pump control valve via the linkage to the governor. | 'e' below: | ||
The TDAFW pump was declared inoperable at 1350 on January 23, 2014 and MPS3 entered into T.S. 3.7.1.2 ACTION c., which states, "Restore the auxiliary feedwater pump to OPERABLE within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." Timely action is needed to avoid an unnecessary plant transient (i.e., plant shutdown to MODE 4) which would begin commencing at 1350 on January 26, 2014.Previous failed operational tests occurred on November 4, 2013 and December 18, 2013. The investigation of these failures identified inadequate condensate removal from the steam supply lines servicing the TDAFW pump as the primary cause of failure. Compensatory actions to improve condensate removal capability were implemented as described in operability determination OD 000561 and remain in effect. Additionally, the testing frequency for the TDAFW pump was increased to monitor its reliability until such time as repairs or redesign of the drain system could be accomplished. | : b. Provide a description of the TS or other license conditions that will be violated, and, if applicable, state that adhering to the license would cause an unnecessary transient. This description shall include the time remaining before the TS or license condition will be violated. When a "regular" NOED is requested, the licensee must show that granting the NOED request would avoid an unnecessary transient. | ||
It was also determined that Terry Turbine Main Steam Control Valve 3MSS*MCV5 should be disassembled and inspected as a near term action. The maintenance activity on 3MSS*MCV5 was scheduled to commence on January 30, 2014.Following the over speed trip of January 23, 2014, site resources were mobilized to investigate and correct the cause of failure on an around the clock basis. Extensive troubleshooting has been performed to focus repair and testing activities. | The TS that will be violated is MPS3 Technical Specification (TS) 3.7.1.2 - Auxiliary Feedwater System. The TS requires: | ||
Vendor representatives and Dominion Fleet experts have also been onsite supporting this effort.There are no outstanding amendment or TS change requests related to this NOED.Additionally, DNC has not previously requested enforcement discretion for MPS3.d. Provide information that shows the licensee fully understands the cause of the situation that has led to the NOED request. The licensee must understand and detail all safety and security concerns when operating outside of its TS or license conditions. | |||
Review of troubleshooting data identified insufficient force being transferred via the linkage to the Terry Turbine Steam Supply Control Valve as the likely cause of the Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 4 of 18 over speed trip on January 23, 2014. The following actions have been performed to investigate and correct any deficiencies | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 2 of 18 "At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE with: | ||
: 1) the Terry Turbine governor has been replaced, 2) the Terry Turbine Main Steam Supply Control Valve (3MSS*MCV5) has been disassembled, inspected, critical dimensions verified and re-installed with vendor support, and 3) the linkage from the governor has been inspected. | : a. Two motor-driven auxiliary feedwater pumps, each capable of being powered from separate emergency busses, and | ||
Binding in the full open position likely due to an incorrectly oriented Heim joint (Linkage element R2) and bearing wear at two additional points in the linkage were identified. | : b. One steam turbine-driven auxiliary feedwater pump capable of being powered from an OPERABLE steam supply system." | ||
These deficiencies were addressed by removal and reinstallation of the Heim joint in the correct orientation, replacement of Linkage R1 including its spherical bearings, and replacement of the cam roller spherical bearing. Freedom of movement was verified following reassembly with no instances of binding throughout the full range of motion.The reassembly of the linkage was verified to be in accordance with its design configuration. | If one auxiliary feedwater pump in MODE 1, 2, or 3, for reasons other than in ACTIONs a. or b. is inoperable, ACTION c. of this TS requires the auxiliary feedwater pump be restored to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours. | ||
Basis Condition report CR537862 documented the "Terry Turbine tripped on over speed" that occurred on January 23, 2014. Review of the surveillance data identified that the valve stem of the Terry Turbine Main Steam Supply Control Valve did not receive sufficient force to properly modulate the steam supply. As a result, the control valve did not adequately control the turbine speed resulting in the over speed trip.Complex troubleshooting was performed using a Terry Turbine Tripped on Over speed Fault Tree which identifies the following possible causes for the over speed trip: 1. AOV Steam Supply stroke rate 2. Moisture in main the steam supply 3. Trip Valve (3MSS*MSV5) performance | The basis of the TS requirement is to ensure a makeup water supply to the steam generators (SGs) is available to support decay heat removal from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply, assuming the worst case single failure. The AFW system consists of two motor driven AFW pumps and one steam turbine driven AFW pump. Each motor driven AFW pump provides at least 50% of the AFW flow capacity assumed in the accident analysis. After reactor shutdown, decay heat eventually decreases so that one motor driven AFW pump can provide sufficient SG makeup flow. The steam driven AFW pump has a rated capacity approximately double that of a motor driven AFW pump and is thus defined as a 100% | ||
: 4. Turbine operation 5. Work practices 6. Pump operation 7. Procedure weaknesses | capacity pump. | ||
: 8. Human Error 9. Linkage performance | Given the worst case single failure, the AFW System is designed to mitigate the consequences of numerous design basis accidents, including Feedwater Line Break, Loss of Normal Feedwater, Steam Generator Tube Rupture, Main Steam Line Break, and Small Break Loss of Coolant Accident. | ||
In addition, given the worst case failure, the AFW is designed to supply sufficient makeup water to replace SG inventory loss as the RCS is cooled to less than 350°F at which point the Residual Heat Removal System may be placed into operation. | |||
Enforcement discretion is requested to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of 36 hours to the AOT. The additional 36 hour duration is needed to support repair and testing activities which are in progress. | |||
At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was GREEN. MPS3 was in TS Action statement 3.7.1.2.c., Auxiliary Feedwater System - One auxiliary feedwater pump inoperable which states: "Restore the auxiliary feedwater pump to OPERABLE status within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 3 of 18 | |||
: c. Provide a description of the circumstances, including as a minimum: likely causes; the need for prompt action; the action taken to avoid the need for a NOED; and any relevant historical events. The historical events must include as a minimum, any other similar events at the plant, the last maintenance performed on the equipment or similar equipment, any outstanding amendment or TS change requests related to the NOED, and the last NOED request from the plant. | |||
On January 23, 2014 the MPS3 Turbine Driven Auxiliary Feedwater (TDAFW) pump tripped during the performance of surveillance procedure SP3622.3 as documented in condition report CR537862. The likely cause of this test failure was insufficient force being applied to the TDAFW pump control valve via the linkage to the governor. The TDAFW pump was declared inoperable at 1350 on January 23, 2014 and MPS3 entered into T.S. 3.7.1.2 ACTION c., which states, "Restore the auxiliary feedwater pump to OPERABLE within 72 hours. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours and in HOT SHUTDOWN within the following 12 hours." Timely action is needed to avoid an unnecessary plant transient (i.e., plant shutdown to MODE 4) which would begin commencing at 1350 on January 26, 2014. | |||
Previous failed operational tests occurred on November 4, 2013 and December 18, 2013. The investigation of these failures identified inadequate condensate removal from the steam supply lines servicing the TDAFW pump as the primary cause of failure. Compensatory actions to improve condensate removal capability were implemented as described in operability determination OD 000561 and remain in effect. Additionally, the testing frequency for the TDAFW pump was increased to monitor its reliability until such time as repairs or redesign of the drain system could be accomplished. It was also determined that Terry Turbine Main Steam Control Valve 3MSS*MCV5 should be disassembled and inspected as a near term action. The maintenance activity on 3MSS*MCV5 was scheduled to commence on January 30, 2014. | |||
Following the over speed trip of January 23, 2014, site resources were mobilized to investigate and correct the cause of failure on an around the clock basis. Extensive troubleshooting has been performed to focus repair and testing activities. Vendor representatives and Dominion Fleet experts have also been onsite supporting this effort. | |||
There are no outstanding amendment or TS change requests related to this NOED. | |||
Additionally, DNC has not previously requested enforcement discretion for MPS3. | |||
: d. Provide information that shows the licensee fully understands the cause of the situation that has led to the NOED request. The licensee must understand and detail all safety and security concerns when operating outside of its TS or license conditions. | |||
Review of troubleshooting data identified insufficient force being transferred via the linkage to the Terry Turbine Steam Supply Control Valve as the likely cause of the | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 4 of 18 over speed trip on January 23, 2014. The following actions have been performed to investigate and correct any deficiencies: 1) the Terry Turbine governor has been replaced, 2) the Terry Turbine Main Steam Supply Control Valve (3MSS*MCV5) has been disassembled, inspected, critical dimensions verified and re-installed with vendor support, and 3) the linkage from the governor has been inspected. Binding in the full open position likely due to an incorrectly oriented Heim joint (Linkage element R2) and bearing wear at two additional points in the linkage were identified. These deficiencies were addressed by removal and reinstallation of the Heim joint in the correct orientation, replacement of Linkage R1 including its spherical bearings, and replacement of the cam roller spherical bearing. Freedom of movement was verified following reassembly with no instances of binding throughout the full range of motion. | |||
The reassembly of the linkage was verified to be in accordance with its design configuration. | |||
Basis Condition report CR537862 documented the "Terry Turbine tripped on over speed" that occurred on January 23, 2014. Review of the surveillance data identified that the valve stem of the Terry Turbine Main Steam Supply Control Valve did not receive sufficient force to properly modulate the steam supply. As a result, the control valve did not adequately control the turbine speed resulting in the over speed trip. | |||
Complex troubleshooting was performed using a Terry Turbine Tripped on Over speed Fault Tree which identifies the following possible causes for the over speed trip: | |||
: 1. AOV Steam Supply stroke rate | |||
: 2. Moisture in main the steam supply | |||
: 3. Trip Valve (3MSS*MSV5) performance | |||
: 4. Turbine operation | |||
: 5. Work practices | |||
: 6. Pump operation | |||
: 7. Procedure weaknesses | |||
: 8. Human Error | |||
: 9. Linkage performance | |||
: 10. Control Valve performance | : 10. Control Valve performance | ||
: 11. Design weaknesses | : 11. Design weaknesses | ||
: 12. Governor performance The subject fault tree evaluates the twelve (12) possible causes of over speed trip.Items one (1) -eight (8), ten (10) and eleven (11) are determined as "not a factor" and the basis is documented on the subject fault tree. Item 2, moisture in the main steam supply was identified as a factor in the previous over speed trips on November 4, 2013 and December 18, 2013. Item 2 (moisture) is not considered a contributor to the January 23, 2014 over speed trip as the compensatory measures established as a result of the previous trips were still in place. Video taken during the January 23, 2014 test also showed a reduction in the amount of condensate being ejected from the valve packing area during TDAFW pump startup. | : 12. Governor performance The subject fault tree evaluates the twelve (12) possible causes of over speed trip. | ||
Items one (1) - eight (8), ten (10) and eleven (11) are determined as "not a factor" and the basis is documented on the subject fault tree. Item 2, moisture in the main steam supply was identified as a factor in the previous over speed trips on November 4, 2013 and December 18, 2013. Item 2 (moisture) is not considered a contributor to the January 23, 2014 over speed trip as the compensatory measures established as a result of the previous trips were still in place. Video taken during the January 23, 2014 test also showed a reduction in the amount of condensate being ejected from the valve packing area during TDAFW pump startup. | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 5 of 18 Prior to the commencement of the January 23, 2014 test, a strain gauge was installed to measure the force being applied to the actuator control valve stem from the linkage of 3MSS*MCV5 (Terry Turbine Main Steam Control Valve). Data collected via the strain gauge indicated insufficient force being transferred through the linkage. Since there was insufficient force on the stem to properly operate the control valve, possible causes 9 (linkage performance) and 12 (governor performance) were selected for further evaluation. | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 5 of 18 Prior to the commencement of the January 23, 2014 test, a strain gauge was installed to measure the force being applied to the actuator control valve stem from the linkage of 3MSS*MCV5 (Terry Turbine Main Steam Control Valve). Data collected via the strain gauge indicated insufficient force being transferred through the linkage. Since there was insufficient force on the stem to properly operate the control valve, possible causes 9 (linkage performance) and 12 (governor performance) were selected for further evaluation. | ||
The steam supply to the Terry Turbine results in Terry Turbine rotor rotation, which turns a spline within the governor. | The steam supply to the Terry Turbine results in Terry Turbine rotor rotation, which turns a spline within the governor. This rotational force provides hydraulic pressure to generate linear governor output. The linear output controls the turbine control valve position; thereby controlling Terry Turbine speed. Governor output is transmitted to the control valve stem via linkage. Consequently, the low force measured within the control valve stem was the result of either low output from the governor or a loss of force measured in the transfer from the governor to the stem (i.e., within the linkage). | ||
This rotational force provides hydraulic pressure to generate linear governor output. The linear output controls the turbine control valve position; thereby controlling Terry Turbine speed. Governor output is transmitted to the control valve stem via linkage. Consequently, the low force measured within the control valve stem was the result of either low output from the governor or a loss of force measured in the transfer from the governor to the stem (i.e., within the linkage).Low Governor Output To address the low governor output concern, the governor was replaced with a newly refurbished governor. | Low Governor Output To address the low governor output concern, the governor was replaced with a newly refurbished governor. This alleviates any concerns with the governor. Potential causes of low governor output are: | ||
This alleviates any concerns with the governor. | " Incorrect oil used within the governor | ||
Potential causes of low governor output are: " Incorrect oil used within the governor" Contaminants within the oil" Governor internal failures Oil samples were taken and sent to laboratory for analysis with testing to be expedited. | " Contaminants within the oil | ||
This will determine if there were contaminants present or if the incorrect oil was used. The replaced governor will be sent to the governor supplier ESI for refurbishment. | " Governor internal failures Oil samples were taken and sent to laboratory for analysis with testing to be expedited. This will determine if there were contaminants present or if the incorrect oil was used. The replaced governor will be sent to the governor supplier ESI for refurbishment. Prior to refurbishment the governor will be inspected and tested to verify proper operation (i.e., expected output). | ||
Prior to refurbishment the governor will be inspected and tested to verify proper operation (i.e., expected output).Linkage Inspection (e.g., high drag, binding)Troubleshooting included a "pull test" of the linkage. Three performances of this test resulted in recorded forces (i.e., 19.7, 24.5, and 23.3 pounds) less than the maximum acceptance criteria of 26 pounds. However, during full stroking of the linkage the cam-plate linkage Heim joint was binding at the full open position. | Linkage Inspection (e.g., high drag, binding) | ||
Visual inspection of this linkage identified the Heim joint was installed backwards (i.e., threaded end installed on bottom versus on top) and corresponding potential binding imprints on the associated clevis. The Heim joint was reinstalled to the correct orientation. | Troubleshooting included a "pull test" of the linkage. Three performances of this test resulted in recorded forces (i.e., 19.7, 24.5, and 23.3 pounds) less than the maximum acceptance criteria of 26 pounds. However, during full stroking of the linkage the cam-plate linkage Heim joint was binding at the full open position. Visual inspection of this linkage identified the Heim joint was installed backwards (i.e., threaded end installed on bottom versus on top) and corresponding potential binding imprints on the associated clevis. The Heim joint was reinstalled to the correct orientation. | ||
Afterwards, freedom of linkage movement was verified subsequent to establishing the correct orientation with no signs of binding throughout the full movement. | Afterwards, freedom of linkage movement was verified subsequent to establishing the correct orientation with no signs of binding throughout the full movement. Pull tests performed following linkage adjustment and control valve maintenance resulted in as left values of 13.3, 12.8, 13.2, and 12.9 pounds indicating a reduction in resistance. | ||
Pull tests performed following linkage adjustment and control valve maintenance resulted in as left values of 13.3, 12.8, 13.2, and 12.9 pounds indicating a reduction in resistance. | Subsequent to the pull test, the linkage was further adjusted to set up correct valve | ||
Subsequent to the pull test, the linkage was further adjusted to set up correct valve Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 6 of 18 stroke and seating. After the linkage adjustment, three additional pull tests were performed to demonstrate continued freedom of movement. | |||
The results from that test were 13.6, 12.9, and 13.3 pounds. The consistent repeatability of the pull test results are considered indicative of effective resolution of linkage binding deficiencies. | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 6 of 18 stroke and seating. After the linkage adjustment, three additional pull tests were performed to demonstrate continued freedom of movement. The results from that test were 13.6, 12.9, and 13.3 pounds. The consistent repeatability of the pull test results are considered indicative of effective resolution of linkage binding deficiencies. | ||
Security concerns related information is included in Section J.e. Detail the proposed course of action to resolve the situation, so enforcement discretion is no longer required.The actions to replace the governor, rebuild the control valve, and rebuild the control valve linkage to the governor have been completed. | Security concerns related information is included in Section J. | ||
The TDAFW pump has been run for some operational checks and governor grooming with satisfactory results. The initial operational test identified the need to replace the associated discharge relief valve. The final test sequence will be conducted after the relief valve repair and testing and when the turbine TDAFW pump has returned to standby conditions. | : e. Detail the proposed course of action to resolve the situation, so enforcement discretion is no longer required. | ||
A full flow test will be performed to satisfy the In Service Testing (IST) retest requirements and validate proper governor operation and control after the maintenance activity. | The actions to replace the governor, rebuild the control valve, and rebuild the control valve linkage to the governor have been completed. The TDAFW pump has been run for some operational checks and governor grooming with satisfactory results. The initial operational test identified the need to replace the associated discharge relief valve. The final test sequence will be conducted after the relief valve repair and testing and when the turbine TDAFW pump has returned to standby conditions. A full flow test will be performed to satisfy the In Service Testing (IST) retest requirements and validate proper governor operation and control after the maintenance activity. If the results of this test indicate that additional tuning of the governor is required then the TDAFW pump will be shutdown and restarted in a maintenance mode to make the necessary adjustments. This process of retesting and adjusting is iterative and may involve multiple cycles to obtain satisfactory performance. Each cycle takes approximately 10 hours to implement. Additionally a quarterly operational test, time response testing, and over speed testing will be performed. Successful execution of the adjustment and retest sequence will lead to acceptable turbine performance and will result in an operable TDAFW pump at which time enforcement discretion will no longer be necessary. | ||
If the results of this test indicate that additional tuning of the governor is required then the TDAFW pump will be shutdown and restarted in a maintenance mode to make the necessary adjustments. | |||
This process of retesting and adjusting is iterative and may involve multiple cycles to obtain satisfactory performance. | |||
Each cycle takes approximately 10 hours to implement. | |||
Additionally a quarterly operational test, time response testing, and over speed testing will be performed. | |||
Successful execution of the adjustment and retest sequence will lead to acceptable turbine performance and will result in an operable TDAFW pump at which time enforcement discretion will no longer be necessary. | |||
: f. Explain that the resolution itself will not result in a different, unnecessary transient. | : f. Explain that the resolution itself will not result in a different, unnecessary transient. | ||
Repairs of the TDAFW pump will not result in a different, unnecessary transient as the TDAFW pump is not an initiator of any event.Following repairs, a full flow/operational readiness test of the TDAFW pump will be performed in Mode 1 to demonstrate operability. | Repairs of the TDAFW pump will not result in a different, unnecessary transient as the TDAFW pump is not an initiator of any event. | ||
This test will be conducted as an Infrequently Conducted or Complex Evolution. | Following repairs, a full flow/operational readiness test of the TDAFW pump will be performed in Mode 1 to demonstrate operability. This test will be conducted as an Infrequently Conducted or Complex Evolution. A safety analysis review of this testing has concluded that there is no more than a minimal increase in the consequences of an accident previously evaluated. | ||
A safety analysis review of this testing has concluded that there is no more than a minimal increase in the consequences of an accident previously evaluated. | : g. Explain that the licensee did not have time to process an emergency license amendment, or that a license amendment is not needed. | ||
: g. Explain that the licensee did not have time to process an emergency license amendment, or that a license amendment is not needed.A license amendment is not needed since this is a one-time request to allow repair and testing of the TDAFW pump. No permanent change to the operating license or the TSs is required. | A license amendment is not needed since this is a one-time request to allow repair and testing of the TDAFW pump. No permanent change to the operating license or the TSs is required. | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 7 of 18 h. Describe the condition and operational status of the plant, including safety-related equipment out of service or otherwise inoperable, and nonsafety-related equipment that is degraded or out of service that may have risk significance and that may increase the probability of a plant transient or may complicate the recovery from a transient or may be used to mitigate the condition. | |||
At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was Green. MPS3 was in TS Action Statement 3.7.1.2. Action c., Auxiliary Feedwater System.Additional Protected Equipment: | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 7 of 18 | ||
* 'B' and 'C' Reactor Plant Chillers and 'A' and 'B' Containment Vacuum Pumps (for'A' CDS Chiller overhaul)" 'B' Emergency Diesel Generator Fuel Oil Transfer Pump ('D' Fuel Oil Transfer Pump breaker maintenance)" 'B' Circulating Water Pump and VFD, 'B' Screen Wash Pump ('A' Circulating Water Bay Outage)* 'B' Control Building Chiller and support equipment | : h. Describe the condition and operational status of the plant, including safety-related equipment out of service or otherwise inoperable, and nonsafety-related equipment that is degraded or out of service that may have risk significance and that may increase the probability of a plant transient or may complicate the recovery from a transient or may be used to mitigate the condition. | ||
('A' Control building chiller outage)* 'A' and 'B' EDGs and both MDAFW pumps (TDAFW pump outage). Per OP-MP-601, Protected Equipment, when 3FWA*P2 is Out of Service: o Place Protected Equipment Barrier around 3FWA*P1A.o Place Protected Equipment Sign on Breaker 34C1 6-2.o Place Protected Equipment Barrier around 3FWA*P1 B.o Place Protected Equipment Sign on Breaker 34D1 5-2.o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-1.o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-3.o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCA. | At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was Green. MPS3 was in TS Action Statement 3.7.1.2. Action c., Auxiliary Feedwater System. | ||
o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-2.o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-4.o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCB." Protect all safety related DC and AC sources in both trains (TSs 3.8.2.1 and 3.8.3.1).Time to Spent Fuel Pool heating to 200°F on loss of all cooling: -92 hours Current Spent Fuel Pool Temperature: | Additional Protected Equipment: | ||
92.0°F Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 8 of 18 Active LCO Actions requiring shutdown within 7 days:* T/S 3.7.1.2 action c. -72 hours for TDAFW Pump Inoperable (tripped on over speed) (expires 1/26/14 at 13:50)Abnormal conditions | * 'B' and 'C' Reactor Plant Chillers and 'A' and 'B' Containment Vacuum Pumps (for | ||
/ Key equipment out of service (OOS): " TDAFW Pump tripped on over speed during testing" 480V non-vital bus 32H intermittent Ground on 'C' Phase" 3SSR*RE08 non-functional due to 3SSR*CTV19B out of service" Non-safety related Battery 6 variable ground The PRA condition is GREEN and it is expected to be GREEN for the duration of the TDAFW pump outage except for a brief period during TDAFW Pump Full Flow testing where it will be YELLOW. Risk significant equipment which is not or will not be available: " 'D' Steam Line to TDAFW Pump" 'D' Diesel Fuel Oil Transfer Pump* 'A' Circ Bay* TDAFW Pump Core Damage Frequency (CDF) Allowed Condition Time (ACT) is 100.2 days and Large Early Release Frequency (LERF) ACT is 159.6 days.i. Request a specific time period for the NOED, including a justification for the duration of the noncompliance. | 'A' CDS Chiller overhaul) | ||
The licensee shall include information that shows its proposed course of action has a high likelihood of being completed within the proposed NOED period. The licensee must show the requested time for the NOED is directly related to the time to resolve the situation. | " 'B' Emergency Diesel Generator Fuel Oil Transfer Pump ('D' Fuel Oil Transfer Pump breaker maintenance) | ||
This enforcement discretion is requested until 0150 hours on January 28, 2014, for TS 3.7.1.2 -Auxiliary Feedwater System.The request for enforcement discretion was made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of the 72 hour AOT. The additional 36 hour duration is needed to support repair and testing activities which are in progress.j. Detail and explain compensatory actions the plant has both taken and will take to reduce the risk associated with the specified configuration. | " 'B' Circulating Water Pump and VFD, 'B' Screen Wash Pump ('A' Circulating Water Bay Outage) | ||
All compensatory actions must be completed before the NOED CT begins.Compensatory measures used to reduce plant vulnerabilities shall focus on both event mitigation and initiating event likelihood. | * 'B' Control Building Chiller and support equipment ('A' Control building chiller outage) | ||
The objectives are to achieve the following: | * 'A' and 'B' EDGs and both MDAFW pumps (TDAFW pump outage). Per OP-MP-601, Protected Equipment, when 3FWA*P2 is Out of Service: | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 9 of 18 1. Reduce the likelihood of initiating events, and 2. Reduce the likelihood of the unavailability of trains redundant to equipment that is out-of-service during the period of enforcement discretion, and 3. Increase the likelihood of successful operator recovery actions in response to initiating events.An example is a situation in which a motor-driven auxiliary feedwater (AFW)pump has failed and risk insights have established that plant transient initiators may be risk-significant events because the plant has no primary feed-and-bleed capability and only limited secondary feed capability is available. | o Place Protected Equipment Barrier around 3FWA*P1A. | ||
As a compensatory measure during the period of enforcement discretion, the licensee may defer non-essential surveillances or other maintenance activities in which human error contributes to the likelihood of a plant trip and subsequent demand on the remaining AFW pumps. Another example of appropriate compensatory measures would be actions that increase the likelihood of success in the manual alignment or start-up of equipment in response to an initiating event (e.g., positioning operators locally at equipment,"just-in-time training", or additional contingency plans).The compensatory actions listed below are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events. To reduce the risk during the duration of the NOED, DNC will take the following compensatory actions: Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components for areas affected when TDAFW pump is OOS: o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are: " CB-1, Control Building West Switchgear Room -El. 4' 6"" CB-2, Control Building East Switchgear Room -El. 4' 6"" CB-8, Control Building Cable Spreading Area -El. 24' 6"" CB-9, Control Building Control Room -El. 47' 6" SCR- 1 .rC frnl Ri lrlinn Inftrllmant I nk-k Pnnm I Indlr flnnr 1=1 | o Place Protected Equipment Sign on Breaker 34C1 6-2. | ||
The licensee must identify any specific transmission line configurations that must be maintained to ensure the availability of the grid for safe operation of the plant.Currently, MPS3 has no offsite or onsite power sources out of service, nor are any planned to be taken out of service during the time period when the proposed NOED will be used. Both MPS3 Emergency Diesel Generators, along with the SBO Diesel Generator, are available with no planned maintenance activities for the proposed NOED time period.1. Include the safety basis for the request and an evaluation of the safety significance and licensee should address the quantitative and qualitative aspects noted below. The numerical guidance for acceptance was established to augment qualitative arguments that continued operation of the plant during the period of enforcement discretion will not cause risk to exceed the level determined acceptable during normal work controls and, therefore, there is no net increase in radiological risk to the public. For licensee provided quantitative risk analysis, the licensee shall provide the effects on LERF. The following information should be provided to support this evaluation: | o Place Protected Equipment Barrier around 3FWA*P1 B. | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 11 of 18 1. Use the zero maintenance PRA model to establish the plant's baseline risk and the estimated risk increase associated with the period of enforcement discretion. | o Place Protected Equipment Sign on Breaker 34D1 5-2. | ||
For the plant-specific configuration the plant intends to operate in during the period of enforcement discretion, the ICCDP and ICLERP should be quantified and compared with guidance thresholds of less than or equal to an ICCDP of 5E-7 and an ICLERP of 5E-8. These numerical guidance values are not pass-fail criteria. | o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-1. | ||
For the degraded case with the subject equipment out of service, the model should reflect, as best as possible, current equipment unavailability states (i.e., if other equipment is unavailable because of T&M, this should also be reflected in the analysis). | o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-3. | ||
This risk calculation should not be limited to the specific TS relief in question, but rather, the total risk of continued operation for the specific configuration of the plant.The MPS3 zero-maintenance internal events risk monitor PRA model, M310R02, was used to estimate the impact on plant risk. The risk impact is associated with the TDAFW pump out-of-service for the duration of the enforcement discretion. | o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCA. | ||
o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-2. | |||
o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-4. | |||
o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCB. | |||
" Protect all safety related DC and AC sources in both trains (TSs 3.8.2.1 and 3.8.3.1). | |||
Time to Spent Fuel Pool heating to 200°F on loss of all cooling: - 92 hours Current Spent Fuel Pool Temperature: 92.0°F | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 8 of 18 Active LCO Actions requiring shutdown within 7 days: | |||
* T/S 3.7.1.2 action c. - 72 hours for TDAFW Pump Inoperable (tripped on over speed) (expires 1/26/14 at 13:50) | |||
Abnormal conditions / Key equipment out of service (OOS): | |||
" TDAFW Pump tripped on over speed during testing | |||
" 480V non-vital bus 32H intermittent Ground on 'C' Phase | |||
" 3SSR*RE08 non-functional due to 3SSR*CTV19B out of service | |||
" Non-safety related Battery 6 variable ground The PRA condition is GREEN and it is expected to be GREEN for the duration of the TDAFW pump outage except for a brief period during TDAFW Pump Full Flow testing where it will be YELLOW. Risk significant equipment which is not or will not be available: | |||
" 'D' Steam Line to TDAFW Pump | |||
" 'D' Diesel Fuel Oil Transfer Pump | |||
* 'A' Circ Bay | |||
* TDAFW Pump Core Damage Frequency (CDF) Allowed Condition Time (ACT) is 100.2 days and Large Early Release Frequency (LERF) ACT is 159.6 days. | |||
: i. Request a specific time period for the NOED, including a justification for the duration of the noncompliance. The licensee shall include information that shows its proposed course of action has a high likelihood of being completed within the proposed NOED period. The licensee must show the requested time for the NOED is directly related to the time to resolve the situation. | |||
This enforcement discretion is requested until 0150 hours on January 28, 2014, for TS 3.7.1.2 - Auxiliary Feedwater System. | |||
The request for enforcement discretion was made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of the 72 hour AOT. The additional 36 hour duration is needed to support repair and testing activities which are in progress. | |||
: j. Detail and explain compensatory actions the plant has both taken and will take to reduce the risk associated with the specified configuration. All compensatory actions must be completed before the NOED CT begins. | |||
Compensatory measures used to reduce plant vulnerabilities shall focus on both event mitigation and initiating event likelihood. The objectives are to achieve the following: | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 9 of 18 | |||
: 1. Reduce the likelihood of initiating events, and | |||
: 2. Reduce the likelihood of the unavailability of trains redundant to equipment that is out-of-service during the period of enforcement discretion, and | |||
: 3. Increase the likelihood of successful operator recovery actions in response to initiating events. | |||
An example is a situation in which a motor-driven auxiliary feedwater (AFW) pump has failed and risk insights have established that plant transient initiators may be risk-significant events because the plant has no primary feed-and-bleed capability and only limited secondary feed capability is available. As a compensatory measure during the period of enforcement discretion, the licensee may defer non-essential surveillances or other maintenance activities in which human error contributes to the likelihood of a plant trip and subsequent demand on the remaining AFW pumps. Another example of appropriate compensatory measures would be actions that increase the likelihood of success in the manual alignment or start-up of equipment in response to an initiating event (e.g., positioning operators locally at equipment, "just-in-time training", or additional contingency plans). | |||
The compensatory actions listed below are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events. To reduce the risk during the duration of the NOED, DNC will take the following compensatory actions: | |||
Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components for areas affected when TDAFW pump is OOS: | |||
o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are: | |||
" CB-1, Control Building West Switchgear Room - El. 4' 6" | |||
" CB-2, Control Building East Switchgear Room - El. 4' 6" | |||
" CB-8, Control Building Cable Spreading Area - El. 24' 6" | |||
" CB-9, Control Building Control Room - El. 47' 6" SCR- 1 .rC frnl Ri lrlinn Inftrllmant I nk-k Pnnm I Indlr flnnr 1=1 46' 6") and Rack Room - El. 47' 6" U SB-2, Service Bldg North Cable Tunnel - El. 4' 6" U SB-3, Service Bldg South Cable Tunnel - El. 4' 6" U | |||
ESF-1, ESF Bldg South Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6" | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 10 of 18 | |||
" ESF-2, ESF Bldg North Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6" | |||
" ESF-4, ESF Bldg East Piping Area - El. 4' 6" | |||
" ESF-7, ESF Bldg Mechanical Equipment Room C - 36' 6" and ESF Bldg Refueling Water Recirc Pumps Area - 21' 6" | |||
" ESF-8, ESF Bldg North MDAFW Pump Area - El. 24' 6" | |||
" ESF-9, ESF Bldg South MDAFW Pump Area - El. 24' 6" and ESF Bldg Mechanical Equipment Room D - El. 36' 6" | |||
* Include area AS-1 D, Auxiliary Building West Floor Area - El. 24' 6" in the implementation of (a)(4) fire risk management actions. | |||
" An operator is continuously staged at the station blackout (SBO) Diesel Generator (DG) | |||
* No planned unit transients, other than those described in the NOED for 4% | |||
downpower and associated full flow test, will be allowed for the duration of the NOED | |||
* No planned switchyard maintenance | |||
" Protect the motor-driven auxiliary feedwater trains, main feedwater system, and condensate system | |||
* Removal of any of the components either due to scheduled or corrective maintenance will be monitored via the Risk Monitor (EOOS) and the MRule (a)(4) process | |||
" The Outage Control Center will be staffed 24/7 until the TDAFW pump is operable and the TS action has been exited. | |||
: k. Discuss the status and potential challenges to offsite and onsite power sources, including any current or planned maintenance in the distribution system and any current or planned maintenance to the emergency diesel generators. The licensee must identify any specific transmission line configurations that must be maintained to ensure the availability of the grid for safe operation of the plant. | |||
Currently, MPS3 has no offsite or onsite power sources out of service, nor are any planned to be taken out of service during the time period when the proposed NOED will be used. Both MPS3 Emergency Diesel Generators, along with the SBO Diesel Generator, are available with no planned maintenance activities for the proposed NOED time period. | |||
: 1. Include the safety basis for the request and an evaluation of the safety significance and licensee should address the quantitative and qualitative aspects noted below. The numerical guidance for acceptance was established to augment qualitative arguments that continued operation of the plant during the period of enforcement discretion will not cause risk to exceed the level determined acceptable during normal work controls and, therefore, there is no net increase in radiological risk to the public. For licensee provided quantitative risk analysis, the licensee shall provide the effects on LERF. The following information should be provided to support this evaluation: | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 11 of 18 | |||
: 1. Use the zero maintenance PRA model to establish the plant's baseline risk and the estimated risk increase associated with the period of enforcement discretion. For the plant-specific configuration the plant intends to operate in during the period of enforcement discretion, the ICCDP and ICLERP should be quantified and compared with guidance thresholds of less than or equal to an ICCDP of 5E-7 and an ICLERP of 5E-8. These numerical guidance values are not pass-fail criteria. For the degraded case with the subject equipment out of service, the model should reflect, as best as possible, current equipment unavailability states (i.e., if other equipment is unavailable because of T&M, this should also be reflected in the analysis). This risk calculation should not be limited to the specific TS relief in question, but rather, the total risk of continued operation for the specific configuration of the plant. | |||
The MPS3 zero-maintenance internal events risk monitor PRA model, M310R02, was used to estimate the impact on plant risk. The risk impact is associated with the TDAFW pump out-of-service for the duration of the enforcement discretion. | |||
ICCDP and ICLERP were calculated using the following equations: | ICCDP and ICLERP were calculated using the following equations: | ||
ICCDP = [Conditional CDF for TDAFW Out-of-Service | ICCDP = [Conditional CDF for TDAFW Out-of-Service - Baseline CDF] * [TDAFW Pump enforcement discretion outage duration] | ||
-Baseline CDF] * [TDAFW Pump enforcement discretion outage duration]ICLERP = [Conditional LERF for TDAFW Out-of-Service | ICLERP = [Conditional LERF for TDAFW Out-of-Service - Baseline LERF] * | ||
-Baseline LERF] *[TDAFW Pump enforcement discretion outage duration]The requested period of enforcement discretion was assumed to be 3 days beyond the technical specification allowed outage time of 3 days (72 hours). The incremental risk associated with this period of operation is: ICCDP = [6.08E-06/yr | [TDAFW Pump enforcement discretion outage duration] | ||
-2.47E-06/yr] | The requested period of enforcement discretion was assumed to be 3 days beyond the technical specification allowed outage time of 3 days (72 hours). The incremental risk associated with this period of operation is: | ||
* [1 yr/365 days | ICCDP = [6.08E-06/yr - 2.47E-06/yr] * [1 yr/365 days | ||
* 3 days] = 2.97E-08 ICLERP = [2.65E-07/yr | * 3 days] = 2.97E-08 ICLERP = [2.65E-07/yr - 3.65E-08/yr] * [1 yr/365 days | ||
-3.65E-08/yr] | * 3 days] = 1.88E-09 The above risk assessment only addresses test and maintenance activities for the TDAFW for the duration of the NOED. All other test, maintenance and environmental conditions are assumed to be in their nominal condition. Any deviations will be addressed via the Risk Monitor (EOOS) and the MRule (a)(4) process. | ||
* [1 yr/365 days | These results are below the NRC Inspection Manual, Chapter 0410 limits of 5E-7 for ICCDP and 5E-8 for ICLERP. | ||
* 3 days] = 1.88E-09 The above risk assessment only addresses test and maintenance activities for the TDAFW for the duration of the NOED. All other test, maintenance and environmental conditions are assumed to be in their nominal condition. | : 2. Discuss the dominant risk contributors (cut sets or sequences or both) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion. This discussion should focus primarily on risk contributors that have changed | ||
Any deviations will be addressed via the Risk Monitor (EOOS) and the MRule (a)(4)process.These results are below the NRC Inspection Manual, Chapter 0410 limits of 5E-7 for ICCDP and 5E-8 for ICLERP.2. Discuss the dominant risk contributors (cut sets or sequences or both) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion. | |||
This discussion should focus primarily on risk contributors that have changed Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 12 of 18 (increased or decreased) from the baseline model because of the degraded condition and resultant compensatory measures, if any.The dominant sequences for Level 1 CDF with the TDAFW Pump unavailable are associated with loss of offsite power, loss of a 4160V AC bus, and loss of a DC bus initiating events. This pump is also important for mitigating several internal flooding scenarios. | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 12 of 18 (increased or decreased) from the baseline model because of the degraded condition and resultant compensatory measures, if any. | ||
The LERF dominant sequences, in addition to the CDF dominant sequences, include mitigation of Steam Generator Tube Rupture (SGTR)initiating events. The important mitigating system is the motor-driven auxiliary feedwater pumps. The important operator action is re-establishing main feedwater and condensate to the steam generators. | The dominant sequences for Level 1 CDF with the TDAFW Pump unavailable are associated with loss of offsite power, loss of a 4160V AC bus, and loss of a DC bus initiating events. This pump is also important for mitigating several internal flooding scenarios. The LERF dominant sequences, in addition to the CDF dominant sequences, include mitigation of Steam Generator Tube Rupture (SGTR) initiating events. The important mitigating system is the motor-driven auxiliary feedwater pumps. The important operator action is re-establishing main feedwater and condensate to the steam generators. | ||
Due to the risk implications with the TDAFW pump unavailable, no maintenance will be planned for the offsite power supply to the plant, the onsite electrical power sources, motor-driven auxiliary feedwater trains, main feedwater system, and condensate system.3. Discuss how the compensatory measures are accounted for in the PRA.These modeled compensatory measures should be correlated, as applicable, to the dominant PRA sequences identified in items 1 and 2 above. In addition, other measures not directly related to the out-of-service equipment may also be implemented to reduce overall plant risk and, as such, should be explained. | Due to the risk implications with the TDAFW pump unavailable, no maintenance will be planned for the offsite power supply to the plant, the onsite electrical power sources, motor-driven auxiliary feedwater trains, main feedwater system, and condensate system. | ||
Compensatory measures that cannot be modeled in the PRA shall be assessed qualitatively. | : 3. Discuss how the compensatory measures are accounted for in the PRA. | ||
The following compensatory measures will be taken: Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components: | These modeled compensatory measures should be correlated, as applicable, to the dominant PRA sequences identified in items 1 and 2 above. In addition, other measures not directly related to the out-of-service equipment may also be implemented to reduce overall plant risk and, as such, should be explained. Compensatory measures that cannot be modeled in the PRA shall be assessed qualitatively. | ||
o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are: " CB-1, Control Building West Switchgear Room -El. 4' 6"" CB-2, Control Building East Switchgear Room -El. 4' 6"" CB-8, Control Building Cable Spreading Area -El. 24' 6"" CB-9, Control Building Control Room -El. 47' 6"" CB-11, Control Building Instrument Rack Room Under floor -(-El.46' 6") and Rack Room -El. 47' 6"" SB-2, Service Bldg North Cable Tunnel -El. 4' 6"" SB-3, Service Bldg South Cable Tunnel -El. 4' 6" Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 13 of 18" ESF-1, ESF Bldg South Cntmt Recirc Cooler Cub -El. -34' 9" to 36' 6"" ESF-2, ESF Bldg North Cntmt Recirc Cooler Cub -El. -34' 9" to 36' 6"" ESF-4, ESF Bldg East Piping Area -El. 4' 6"" ESF-7, ESF Bldg Mechanical Equipment Room C -El- 36' 6" and ESF Bldg Refueling Water Recirc Pumps Area -El- 21' 6"" ESF-8, ESF Bldg North MDAFW Pump Area -El. 24' 6"" ESF-9, ESF Bldg South MDAFW Pump Area -El. 24' 6" and ESF Bldg Mechanical Equipment Room D -El- 36' 6"" Include area AS-1 D, Auxiliary Building West Floor Area -El. 24' 6" in the implementation of (a)(4) fire risk management actions." An operator is continuously staged at the station blackout (SBO) diesel generator (DG) in accordance with Security Risk requirements." No planned unit transients, other than those described in the NOED for 4%downpower and associated full flow test, will be allowed for the duration of the NOED* No planned switchyard maintenance | The following compensatory measures will be taken: | ||
* Protect the motor-driven auxiliary feedwater trains, main feedwater system, and condensate system* Removal of any of the components either due to scheduled or corrective maintenance will be monitored via the Risk Monitor (EOOS) and the MRule (a)(4) process None of the compensatory measures listed above are directly accounted for in the PRA calculation of ICCDP and ICLERP. The actions are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events.4. Discuss the "extent of condition" of the failed or unavailable component(s) to other trains or divisions of equipment and the adjustments, if any, which were made to the related PRA common cause factors to account for potential increases in their failure probabilities. | Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components: | ||
The method used to determine the extent of condition shall be discussed. | o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are: | ||
It is recognized that a formal root cause or apparent cause is not required because of the limited time available in determining the acceptability of a requested NOED. However, a discussion of the likely cause shall be provided with an associated discussion of the potential for common cause failure.The extent of condition is limited to the TDAFW pump since the failure mechanism is associated with the turbine speed control function of the pump. No other equipment in the AFW common cause component group shares this design for motive force. As a result, no adjustments have been made to the PRA to account for common cause factor and potential increases in common cause failure probabilities. | " CB-1, Control Building West Switchgear Room - El. 4' 6" | ||
Additionally, the MPS3 emergency diesel generators use control systems which are sufficiently different from the one used with the TDAFW pump Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 14 of 18 (i.e. Woodward EGB versus Woodward PGG) such that the extent of condition is not applicable to the MPS3 emergency diesel generators. | " CB-2, Control Building East Switchgear Room - El. 4' 6" | ||
The MPS3 emergency diesel generators have been successfully tested and operated with no similar adverse conditions. | " CB-8, Control Building Cable Spreading Area - El. 24' 6" | ||
: 5. Discuss external event risk for the specified plant configuration. | " CB-9, Control Building Control Room - El. 47' 6" | ||
An example of external event risk is a situation in which a reactor core isolation cooling (RCIC) pump has failed and a review of the licensee's Individual Plant Examination of External Events or full-scope PRA model identifies that the RCIC pump is used to mitigate certain fire scenarios. | " CB-11, Control Building Instrument Rack Room Under floor - (-El. | ||
Action may be taken to reduce fire ignition frequency in the affected areas and to reduce human error associated with time-critical operator actions in response to such scenarios, and to ensure fire protective and corrective measures have been taken.The MPS3 PRA is a level 1 and 2 (LERF) model that includes internal events and internal floods. For external events (e.g., fire, seismic, external floods, high winds)the IPEEE is used for risk insights.Fire The MPS3 internal events PRA does not include a fire model. Therefore, the fire risk is qualitatively assessed using the IPEEE. The IPEEE fire risk quantified a CDF impact by combining the frequency of fires and the probability of detection/suppression failure with the remaining safety function random failures. | 46' 6") and Rack Room - El. 47' 6" | ||
A systematic approach was used to identify critical fire areas where fires could fail safety functions and pose an increased risk of core damage if other safety functions are unavailable. | " SB-2, Service Bldg North Cable Tunnel - El. 4' 6" | ||
The CDF due to fires is 4.8E-6/yr, with the dominant risk being fires in the cable spreading room, switchgear rooms, control room, and auxiliary building.To mitigate the potential impact to fire risk, DNC will implement compensatory measures in accordance with the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1. The compensatory actions include the affected areas, cable spreading room (CB-8), switchgear rooms (CB-1 and CB-2), and control room (CB-9). Though the TRM does not require fire risk management actions for the Auxiliary Building location containing the Charging and Reactor Building Component Cooling Water Pumps, fire zone AS-1 D has been added to the compensatory measures based on risk insights from the IPEEE.Seismic The MPS3 internal events PRA does not include a seismic model. The IPEEE quantified a CDF impact by combining the seismic hazard frequencies with the fragilities of critical structures and components and the safety function random failures. | " SB-3, Service Bldg South Cable Tunnel - El. 4' 6" | ||
The CDF due to seismic events is 9.1E-06/yr, with the dominant risk being seismic events that result in a loss of offsite power and failure of the Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 15 of 18 emergency diesel generator enclosures, or collapse of the control building. | |||
A review of the cutsets associated with loss of offsite power and early core melt (contributes 63% Seismic CDF) found that random failure of the auxiliary feedwater system does not significantly contribute to the seismic risk. Therefore, this NOED will not significantly impact the seismic risk.High Winds, External Floods, and Other Events The risk of other external events such as high winds, external flooding, aircraft accidents, hazardous materials, and turbine missiles was assessed in the MPS3 IPEEE. The IPEEE assessments concluded that the risk of these accidents is negligible primarily due to the low frequency of occurrence that would cause damage to mitigating systems. For example, reinforced concrete houses provide the applicable safety systems missile protection during high winds. Note the potential for high winds is covered under section n, which provides a discussion on forecasted weather.m. Demonstrate that the NOED condition, along with any compensatory measures, will not result in more than a minimal increase in radiological risk, either in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner.The PRA evaluation calculates the change in risk associated with an assumed 72 hour NOED for TDAFW Pump unavailability. | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 13 of 18 | ||
The ICCDP is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP is 1.88E-09, which is below the 5E-8 threshold. | " ESF-1, ESF Bldg South Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6" | ||
The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP.n. Discuss forecasted weather and pandemic conditions for the requested NOED period and any plant vulnerabilities related to weather or pandemic conditions. | " ESF-2, ESF Bldg North Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6" | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 16 of 18 Daily Forecast for GROTON, CT (KGON)DSun Man ; Tue VWd Thu ; I I " | " ESF-4, ESF Bldg East Piping Area - El. 4' 6" | ||
* Mon | " ESF-7, ESF Bldg Mechanical Equipment Room C -El- 36' 6" and ESF Bldg Refueling Water Recirc Pumps Area -El- 21' 6" | ||
*F) 17/31 22143 11(23 11129 15/33 25M40 26/42 29/42 26/35 25/38 23/46 22/34 20/31 1 18/31 19/31 17/32 (LoIII)Feels Like (F) 2/22 12127 -2118 0/19 6/27 16/33 20/38 21/37 18/28 16/32 13/40 11/25 8/22 6122 7(21 5n24 (Lo/14)Wet Bulb (*F) ', (Le/l) 13/29 17/43 8/17 9/22 12/28 24/33 25/41 27/42 24/32 25134 22/41 20/28 19/28 .17/26 18/28 16/2B Dew Polnt (*F) 11 22 -3 1 2 11 22 26 28 24 27 22 18 20 156 19 20 Humldity(*A 57 60 33 39 54 60 66 71 78 | " ESF-8, ESF Bldg North MDAFW Pump Area - El. 24' 6" | ||
0.04 '0 L L .:'.06 Evapotransplration Unchesiday) 0.06 0.07 1 0.05 0.06 0.05 r 0.05 0.04 0.04 0.03 0.03 0.08 0.05 003 0.04 0.03 0.03 There are no additional plant vulnerabilities related to the weather conditions for the duration of the NOED.o. Include the basis for the licensee's conclusion the noncompliance will not create undue risk to public health and safety.The request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of the allowed outage time (AOT) for an additional 36 hours for an inoperable auxiliary feedwater pump, does not result in a significant hazards consideration as defined in 10 CFR 50.92. Specifically, the proposed enforcement discretion does not:* Involve a significant increase in the probability or consequences of an accident previously evaluated. | " ESF-9, ESF Bldg South MDAFW Pump Area - El. 24' 6" and ESF Bldg Mechanical Equipment Room D -El- 36' 6" | ||
The ICCDP, based on an assumed additional 72 hour AOT, is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP, based on an assumed additional 72 hour AOT, is 1.88E-09, which is below the 5E-8 threshold. | " Include area AS-1 D, Auxiliary Building West Floor Area - El. 24' 6" in the implementation of (a)(4) fire risk management actions. | ||
The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP.Allowing an additional 36 hours for the repairs associated with the TDAFW pump is acceptable since the AFW system remains capable of performing its intended function. | " An operator is continuously staged at the station blackout (SBO) diesel generator (DG) in accordance with Security Risk requirements. | ||
During the extended maintenance and test period, the compensatory actions identified in section J. will be implemented. | " No planned unit transients, other than those described in the NOED for 4% | ||
Therefore, the consequences of accidents related to or dependent on AFW system operation will not be significantly affected.* Create the possibility of a new or different kind of accident from any accident previously evaluated. | downpower and associated full flow test, will be allowed for the duration of the NOED | ||
There are no new failure modes or mechanisms associated with plant operation for an extended period to perform maintenance and testing on the TDAFW pump. Extended operation with an inoperable TDAFW pump does not involve any modification in the operational limits or Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 17 of 18 physical design of the involved systems. Therefore, there are no new accident precursors generated due to the extended maintenance and testing period.Involve a significant reduction in a margin of safety. Plant operation for an additional 36 hours with the inoperable TDAFW pump does not adversely affect the margin of safety. During the extended maintenance and testing period the AFW system remains capable of performing its intended safety function. | * No planned switchyard maintenance | ||
The compensatory measures identified in section J. will remain in effect for the time period when the proposed NOED will be used to assure safety margins are maintained. | * Protect the motor-driven auxiliary feedwater trains, main feedwater system, and condensate system | ||
* Removal of any of the components either due to scheduled or corrective maintenance will be monitored via the Risk Monitor (EOOS) and the MRule (a)(4) process None of the compensatory measures listed above are directly accounted for in the PRA calculation of ICCDP and ICLERP. The actions are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events. | |||
: 4. Discuss the "extent of condition" of the failed or unavailable component(s) to other trains or divisions of equipment and the adjustments, if any, which were made to the related PRA common cause factors to account for potential increases in their failure probabilities. The method used to determine the extent of condition shall be discussed. It is recognized that a formal root cause or apparent cause is not required because of the limited time available in determining the acceptability of a requested NOED. However, a discussion of the likely cause shall be provided with an associated discussion of the potential for common cause failure. | |||
The extent of condition is limited to the TDAFW pump since the failure mechanism is associated with the turbine speed control function of the pump. No other equipment in the AFW common cause component group shares this design for motive force. As a result, no adjustments have been made to the PRA to account for common cause factor and potential increases in common cause failure probabilities. Additionally, the MPS3 emergency diesel generators use control systems which are sufficiently different from the one used with the TDAFW pump | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 14 of 18 (i.e. Woodward EGB versus Woodward PGG) such that the extent of condition is not applicable to the MPS3 emergency diesel generators. The MPS3 emergency diesel generators have been successfully tested and operated with no similar adverse conditions. | |||
: 5. Discuss external event risk for the specified plant configuration. An example of external event risk is a situation in which a reactor core isolation cooling (RCIC) pump has failed and a review of the licensee's Individual Plant Examination of External Events or full-scope PRA model identifies that the RCIC pump is used to mitigate certain fire scenarios. Action may be taken to reduce fire ignition frequency in the affected areas and to reduce human error associated with time-critical operator actions in response to such scenarios, and to ensure fire protective and corrective measures have been taken. | |||
The MPS3 PRA is a level 1 and 2 (LERF) model that includes internal events and internal floods. For external events (e.g., fire, seismic, external floods, high winds) the IPEEE is used for risk insights. | |||
Fire The MPS3 internal events PRA does not include a fire model. Therefore, the fire risk is qualitatively assessed using the IPEEE. The IPEEE fire risk quantified a CDF impact by combining the frequency of fires and the probability of detection/suppression failure with the remaining safety function random failures. A systematic approach was used to identify critical fire areas where fires could fail safety functions and pose an increased risk of core damage if other safety functions are unavailable. The CDF due to fires is 4.8E-6/yr, with the dominant risk being fires in the cable spreading room, switchgear rooms, control room, and auxiliary building. | |||
To mitigate the potential impact to fire risk, DNC will implement compensatory measures in accordance with the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1. The compensatory actions include the affected areas, cable spreading room (CB-8), switchgear rooms (CB-1 and CB-2), and control room (CB-9). Though the TRM does not require fire risk management actions for the Auxiliary Building location containing the Charging and Reactor Building Component Cooling Water Pumps, fire zone AS-1 D has been added to the compensatory measures based on risk insights from the IPEEE. | |||
Seismic The MPS3 internal events PRA does not include a seismic model. The IPEEE quantified a CDF impact by combining the seismic hazard frequencies with the fragilities of critical structures and components and the safety function random failures. The CDF due to seismic events is 9.1E-06/yr, with the dominant risk being seismic events that result in a loss of offsite power and failure of the | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 15 of 18 emergency diesel generator enclosures, or collapse of the control building. A review of the cutsets associated with loss of offsite power and early core melt (contributes 63% Seismic CDF) found that random failure of the auxiliary feedwater system does not significantly contribute to the seismic risk. Therefore, this NOED will not significantly impact the seismic risk. | |||
High Winds, External Floods, and Other Events The risk of other external events such as high winds, external flooding, aircraft accidents, hazardous materials, and turbine missiles was assessed in the MPS3 IPEEE. The IPEEE assessments concluded that the risk of these accidents is negligible primarily due to the low frequency of occurrence that would cause damage to mitigating systems. For example, reinforced concrete houses provide the applicable safety systems missile protection during high winds. Note the potential for high winds is covered under section n, which provides a discussion on forecasted weather. | |||
: m. Demonstrate that the NOED condition, along with any compensatory measures, will not result in more than a minimal increase in radiological risk, either in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner. | |||
The PRA evaluation calculates the change in risk associated with an assumed 72 hour NOED for TDAFW Pump unavailability. The ICCDP is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP is 1.88E-09, which is below the 5E-8 threshold. The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP. | |||
: n. Discuss forecasted weather and pandemic conditions for the requested NOED period and any plant vulnerabilities related to weather or pandemic conditions. | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 16 of 18 Daily Forecast for GROTON, CT (KGON) | |||
DSun Man ; Tue VWd Thu ; I I " | |||
* Mon E. | |||
1/26 !1F27 Dat 1128 129 1 Fr/31 Sat2/1 'Sun 212 Mon2/3 Tue2A4 Wed225,Thu2/6 Fri 2/7 Sat2/8 Sun2/9 2110 WeatherCondion Afternoon 0 - | |||
Sn*w Weathr Rn .non ,, Partly Mostly Afternoon Partly Partly Flurries Snow Partly Snow Mostly Snow . Partly Weter S ow ansunnSnn . . Cloudy uyoudyCloudy IFlurriesCluylodLieyieya r Cloudy Cloudy Likely Likely Cloudy Likely Cloudy: Likely Cloudy P.ossibl Temperature *F) 17/31 22143 11(23 11129 15/33 25M40 26/42 29/42 26/35 25/38 23/46 22/34 20/31 1 18/31 19/31 17/32 (LoIII) | |||
Feels Like (F) 2/22 12127 -2118 0/19 6/27 16/33 20/38 21/37 18/28 16/32 13/40 11/25 8/22 6122 7(21 5n24 (Lo/14) | |||
Wet Bulb (*F) ', | |||
(Le/l) 13/29 17/43 8/17 9/22 12/28 24/33 25/41 27/42 24/32 25134 22/41 20/28 19/28 . 17/26 18/28 16/2B Dew Polnt (*F) 11 22 -3 1 2 11 22 26 28 24 27 22 18 20 156 19 20 Humldity(*A 57 60 33 39 54 60 66 71 78 822 53 57 76 .62 7573 Wind Speed (mph) 13 11 7 9 7 9 5 6 6 8 10 I 10 | |||
* 9 I 11 Preclpltatdon 36 60 5 '0 60, 7 5 Precipitation Rain S 1/4 S:<1/4 I S:1-3 1S:144-1N S1-3 Amount Trace R None None None I None None No ne ,L:.25 None L0 ne N1ne (Raln:ln.Snow:ln.) 0.04 '0 L L .:'.06 Evapotransplration Unchesiday) 0.06 0.07 1 0.05 0.06 0.05 r 0.05 0.04 0.04 0.03 0.03 0.08 0.05 003 0.04 0.03 0.03 There are no additional plant vulnerabilities related to the weather conditions for the duration of the NOED. | |||
: o. Include the basis for the licensee's conclusion the noncompliance will not create undue risk to public health and safety. | |||
The request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of the allowed outage time (AOT) for an additional 36 hours for an inoperable auxiliary feedwater pump, does not result in a significant hazards consideration as defined in 10 CFR 50.92. Specifically, the proposed enforcement discretion does not: | |||
* Involve a significant increase in the probability or consequences of an accident previously evaluated. The ICCDP, based on an assumed additional 72 hour AOT, is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP, based on an assumed additional 72 hour AOT, is 1.88E-09, which is below the 5E-8 threshold. The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP. | |||
Allowing an additional 36 hours for the repairs associated with the TDAFW pump is acceptable since the AFW system remains capable of performing its intended function. During the extended maintenance and test period, the compensatory actions identified in section J. will be implemented. Therefore, the consequences of accidents related to or dependent on AFW system operation will not be significantly affected. | |||
* Create the possibility of a new or different kind of accident from any accident previously evaluated. There are no new failure modes or mechanisms associated with plant operation for an extended period to perform maintenance and testing on the TDAFW pump. Extended operation with an inoperable TDAFW pump does not involve any modification in the operational limits or | |||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 17 of 18 physical design of the involved systems. Therefore, there are no new accident precursors generated due to the extended maintenance and testing period. | |||
Involve a significant reduction in a margin of safety. Plant operation for an additional 36 hours with the inoperable TDAFW pump does not adversely affect the margin of safety. During the extended maintenance and testing period the AFW system remains capable of performing its intended safety function. The compensatory measures identified in section J. will remain in effect for the time period when the proposed NOED will be used to assure safety margins are maintained. | |||
: p. Include the basis for the licensee's conclusion the noncompliance will not involve adverse consequences to the environment. | : p. Include the basis for the licensee's conclusion the noncompliance will not involve adverse consequences to the environment. | ||
The request for enforcement discretion does not change requirements with respect to the installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. | The request for enforcement discretion does not change requirements with respect to the installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. | ||
Specifically, the request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.Accordingly, the request for enforcement discretion meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). | Specifically, the request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. | ||
Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment for the request is not required.q. Include a statement that the facility organization that normally reviews safety issues has approved the request (Plant Onsite Review Committee, or its equivalent). | Accordingly, the request for enforcement discretion meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment for the request is not required. | ||
The Facility Safety Review Committee has reviewed and concurs with this request.r. Make a verbal commitment that the licensee will submit the written NOED request within 2 working days and a follow-up license amendment request within 4 working days following the staff's verbal granting of the NOED. NRC's granting of a NOED means that exigent circumstances exist. However, the licensee's amendment request must describe and justify any exigent circumstances (see 10 CFR 50.91(a)(6)). | : q. Include a statement that the facility organization that normally reviews safety issues has approved the request (Plant Onsite Review Committee, or its equivalent). | ||
If the staff agrees during the conference call that a follow-up amendment request is not required, the licensee shall state this in the written NOED request. If the licensee intends to propose a temporary amendment, the licensee's amendment request shall include justification for the temporary nature of the request.A license amendment is not being requested. | The Facility Safety Review Committee has reviewed and concurs with this request. | ||
The requested NOED represents a request for enforcement discretion for a temporary, specific period of time in which MPS3 seeks to extend the AOT for TS ACTION 3.7.2.1 .c. for an additional 36 hours in order to allow completion of repairs, and restore the TDAFW PUMP to OPERABLE status. | : r. Make a verbal commitment that the licensee will submit the written NOED request within 2 working days and a follow-up license amendment request within 4 working days following the staff's verbal granting of the NOED. NRC's granting of a NOED means that exigent circumstances exist. However, the licensee's amendment request must describe and justify any exigent circumstances (see 10 CFR 50.91(a)(6)). If the staff agrees during the conference call that a follow-up amendment request is not required, the licensee shall state this in the written NOED request. If the licensee intends to propose a temporary amendment, the licensee's amendment request shall include justification for the temporary nature of the request. | ||
Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 18 of 18 s. In addition to items a thru r above, the licensee must provide the following information for a natural event NOED: 1. List the name, organization, and telephone number of the official in the government or independent entity who made the emergency determination, if applicable. | A license amendment is not being requested. The requested NOED represents a request for enforcement discretion for a temporary, specific period of time in which MPS3 seeks to extend the AOT for TS ACTION 3.7.2.1 .c. for an additional 36 hours in order to allow completion of repairs, and restore the TDAFW PUMP to OPERABLE status. | ||
If deemed necessary, the staff may contact the appropriate official to independently verify the information the licensee provided before making a NOED determination. | |||
: 2. Include details of the basis and nature of the emergency including, but not limited to, its effect on the following: (a.) on-site and off-site emergency preparedness, (b.) plant and site ingress and egress, (c.) off-site and on-site power sources, (d.) plant security, (e.) grid stability, and (f.) actions taken to avert or alleviate the emergency situation (e.g., coordinating with other utilities and the load dispatcher organization for buying additional power or for cycling loads, or shedding interruptible industrial or non-emergency loads).3. Identify and discuss the potential consequences of compliance with existing license requirements (e.g., plant trip, controlled shutdown). | Serial No. 14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 18 of 18 | ||
: s. In addition to items a thru r above, the licensee must provide the following information for a natural event NOED: | |||
: 1. List the name, organization, and telephone number of the official in the government or independent entity who made the emergency determination, if applicable. If deemed necessary, the staff may contact the appropriate official to independently verify the information the licensee provided before making a NOED determination. | |||
: 2. Include details of the basis and nature of the emergency including, but not limited to, its effect on the following: | |||
(a.) on-site and off-site emergency preparedness, (b.) plant and site ingress and egress, (c.) off-site and on-site power sources, (d.) plant security, (e.) grid stability, and (f.) actions taken to avert or alleviate the emergency situation (e.g., | |||
coordinating with other utilities and the load dispatcher organization for buying additional power or for cycling loads, or shedding interruptible industrial or non-emergency loads). | |||
: 3. Identify and discuss the potential consequences of compliance with existing license requirements (e.g., plant trip, controlled shutdown). | |||
: 4. Discuss the potential adverse effects on public health and safety from enforcing compliance with specific license requirements during the emergency. | : 4. Discuss the potential adverse effects on public health and safety from enforcing compliance with specific license requirements during the emergency. | ||
: 5. Discuss the impact of the emergency on plant safety, including any limitations of the UHS.6 For a grid instability NOED, assure the NRC that all reasonable opportunities for purchasing replacement power have been exhausted, and the NOED shall not last any longer than replacement power becomes available, if applicable. | : 5. Discuss the impact of the emergency on plant safety, including any limitations of the UHS. | ||
6 For a grid instability NOED, assure the NRC that all reasonable opportunities for purchasing replacement power have been exhausted, and the NOED shall not last any longer than replacement power becomes available, if applicable. | |||
Not applicable as this is not a natural event NOED.}} | Not applicable as this is not a natural event NOED.}} |
Latest revision as of 09:43, 4 November 2019
ML14036A095 | |
Person / Time | |
---|---|
Site: | Millstone ![]() |
Issue date: | 01/28/2014 |
From: | Scace S Dominion, Dominion Nuclear Connecticut |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
14-043 | |
Download: ML14036A095 (21) | |
Text
Dominion Nuclear Connecticut, Inc.
Rope Ferry Rd., Waterford, CT 06385 JWEEE.E..W..
Mailing Address: P.O. Box 128 JAN 28 2014 Waterford, CT 06385 don .conm U.S. Nuclear Regulatory Commission Serial No.14-043 Attention: Document Control Desk MPS Lic/MLC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 REQUEST FOR ENFORCEMENT DISCRETION FROM TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM In a teleconference call on January 26, 2014, Dominion Nuclear Connecticut, Inc.
(DNC) informed the NRC staff of the need for a notice of enforcement discretion (NOED) from the requirements of Millstone Power Station Unit 3 (MPS3) Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater System, which states, "At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE," with ACTION c. stating for Inoperable Equipment, "One auxiliary feedwater pump in MODE 1, 2, or 3 for reasons other than a. or b. above. Restore the auxiliary feedwater pump to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />."
This NOED request (regular) is being made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension period of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> prior to initiating shutdown of the unit.
The Facility Safety Review Committee has reviewed and concurs with this request.
This NOED request was verbally approved by the NRC on January 26, 2014 at approximately 1245 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.737225e-4 months <br />. Per NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC is required to submit a written request for the NOED within two working days of the oral request for a regular NOED. This letter and its attachments provide the information documenting DNC's request.
The turbine driven auxiliary feedwater pump was restored to OPERABLE status at 0505 on January 27, 2014. The compensatory actions to review existing transient combustible permits, existing ignition sources, racking breakers and perform area walkdowns for the affected fire areas, and to brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas were completed at 1800 January 26, 2014.
There are no regulatory commitments contained in this letter.
bP-
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Page 2 of 2 If you should have any questions regarding this submittal, please contact Wanda Craft at (804) 273-4687.
Sincel S. E. Scace Site Vice President - Millstone
Attachment:
- 1. Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2 - Auxiliary Feedwater System cc: U.S. Nuclear Regulatory Commission Region 1 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 J. S. Kim Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop 08-C2A Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station
Serial No.14-043 Docket No. 50-423 ATTACHMENT 1 REQUEST FOR ENFORCEMENT DISCRETION FROM THE REQUIREMENTS OF TECHNICAL SPECIFICATION 3.7.1.2. AUXILIARY FEEDWATER SYSTEM MILLSTONE POWER STATION UNIT 3 DOMINION NUCLEAR CONNECTICUT, INC. (DNC)
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1 Page 1 of 18 Request for Enforcement Discretion from the Requirements of Technical Specification 3.7.1.2, Auxiliary Feedwater System Introduction Dominion Nuclear Connecticut, Inc. (DNC) hereby requests the NRC staff to exercise discretion not to enforce compliance with the Millstone Power Station Unit 3 (MPS3)
Technical Specification (TS) 3.7.1.2, Auxiliary Feedwater (AFW) System.
Discussion of the Requirements for which Enforcement Discretion is Requested Consistent with NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion," DNC herein provides a supporting description and justification for issuance of the requested notice of enforcement discretion (NOED).
- a. Specifically address what type of NOED is being requested (regular or natural event), which of the NOED criteria for appropriate plant conditions specified in subsection 03.03 of this guidance is satisfied, and how the licensee satisfied those criteria. (also reference subsection 06.02 of this IMC)
A regular NOED is being requested in accordance with NOED Criterion 03.03(b) of NRC Inspection Manual, Chapter 0410, "Notices of Enforcement Discretion". Criterion 03.03(b) involves the following condition: "an unnecessary down-power or the shutdown of a reactor without a corresponding health and safety benefit."
This enforcement discretion is requested until 0150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> on January 28, 2014, for TS 3.7.1.2 - Auxiliary Feedwater System.
The request for enforcement discretion was made to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to the existing allowed outage time (AOT) of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for an inoperable auxiliary feedwater pump. The 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> duration is needed to support repair and testing activities which are in progress. See detailed information in section
'e' below:
- b. Provide a description of the TS or other license conditions that will be violated, and, if applicable, state that adhering to the license would cause an unnecessary transient. This description shall include the time remaining before the TS or license condition will be violated. When a "regular" NOED is requested, the licensee must show that granting the NOED request would avoid an unnecessary transient.
The TS that will be violated is MPS3 Technical Specification (TS) 3.7.1.2 - Auxiliary Feedwater System. The TS requires:
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 2 of 18 "At least three independent steam generator auxiliary feedwater pumps and associated flow paths shall be OPERABLE with:
- a. Two motor-driven auxiliary feedwater pumps, each capable of being powered from separate emergency busses, and
- b. One steam turbine-driven auxiliary feedwater pump capable of being powered from an OPERABLE steam supply system."
If one auxiliary feedwater pump in MODE 1, 2, or 3, for reasons other than in ACTIONs a. or b. is inoperable, ACTION c. of this TS requires the auxiliary feedwater pump be restored to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The basis of the TS requirement is to ensure a makeup water supply to the steam generators (SGs) is available to support decay heat removal from the Reactor Coolant System (RCS) upon the loss of normal feedwater supply, assuming the worst case single failure. The AFW system consists of two motor driven AFW pumps and one steam turbine driven AFW pump. Each motor driven AFW pump provides at least 50% of the AFW flow capacity assumed in the accident analysis. After reactor shutdown, decay heat eventually decreases so that one motor driven AFW pump can provide sufficient SG makeup flow. The steam driven AFW pump has a rated capacity approximately double that of a motor driven AFW pump and is thus defined as a 100%
capacity pump.
Given the worst case single failure, the AFW System is designed to mitigate the consequences of numerous design basis accidents, including Feedwater Line Break, Loss of Normal Feedwater, Steam Generator Tube Rupture, Main Steam Line Break, and Small Break Loss of Coolant Accident.
In addition, given the worst case failure, the AFW is designed to supply sufficient makeup water to replace SG inventory loss as the RCS is cooled to less than 350°F at which point the Residual Heat Removal System may be placed into operation.
Enforcement discretion is requested to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to the AOT. The additional 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> duration is needed to support repair and testing activities which are in progress.
At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was GREEN. MPS3 was in TS Action statement 3.7.1.2.c., Auxiliary Feedwater System - One auxiliary feedwater pump inoperable which states: "Restore the auxiliary feedwater pump to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />."
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 3 of 18
- c. Provide a description of the circumstances, including as a minimum: likely causes; the need for prompt action; the action taken to avoid the need for a NOED; and any relevant historical events. The historical events must include as a minimum, any other similar events at the plant, the last maintenance performed on the equipment or similar equipment, any outstanding amendment or TS change requests related to the NOED, and the last NOED request from the plant.
On January 23, 2014 the MPS3 Turbine Driven Auxiliary Feedwater (TDAFW) pump tripped during the performance of surveillance procedure SP3622.3 as documented in condition report CR537862. The likely cause of this test failure was insufficient force being applied to the TDAFW pump control valve via the linkage to the governor. The TDAFW pump was declared inoperable at 1350 on January 23, 2014 and MPS3 entered into T.S. 3.7.1.2 ACTION c., which states, "Restore the auxiliary feedwater pump to OPERABLE within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If these ACTIONS are not met, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />." Timely action is needed to avoid an unnecessary plant transient (i.e., plant shutdown to MODE 4) which would begin commencing at 1350 on January 26, 2014.
Previous failed operational tests occurred on November 4, 2013 and December 18, 2013. The investigation of these failures identified inadequate condensate removal from the steam supply lines servicing the TDAFW pump as the primary cause of failure. Compensatory actions to improve condensate removal capability were implemented as described in operability determination OD 000561 and remain in effect. Additionally, the testing frequency for the TDAFW pump was increased to monitor its reliability until such time as repairs or redesign of the drain system could be accomplished. It was also determined that Terry Turbine Main Steam Control Valve 3MSS*MCV5 should be disassembled and inspected as a near term action. The maintenance activity on 3MSS*MCV5 was scheduled to commence on January 30, 2014.
Following the over speed trip of January 23, 2014, site resources were mobilized to investigate and correct the cause of failure on an around the clock basis. Extensive troubleshooting has been performed to focus repair and testing activities. Vendor representatives and Dominion Fleet experts have also been onsite supporting this effort.
There are no outstanding amendment or TS change requests related to this NOED.
Additionally, DNC has not previously requested enforcement discretion for MPS3.
- d. Provide information that shows the licensee fully understands the cause of the situation that has led to the NOED request. The licensee must understand and detail all safety and security concerns when operating outside of its TS or license conditions.
Review of troubleshooting data identified insufficient force being transferred via the linkage to the Terry Turbine Steam Supply Control Valve as the likely cause of the
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 4 of 18 over speed trip on January 23, 2014. The following actions have been performed to investigate and correct any deficiencies: 1) the Terry Turbine governor has been replaced, 2) the Terry Turbine Main Steam Supply Control Valve (3MSS*MCV5) has been disassembled, inspected, critical dimensions verified and re-installed with vendor support, and 3) the linkage from the governor has been inspected. Binding in the full open position likely due to an incorrectly oriented Heim joint (Linkage element R2) and bearing wear at two additional points in the linkage were identified. These deficiencies were addressed by removal and reinstallation of the Heim joint in the correct orientation, replacement of Linkage R1 including its spherical bearings, and replacement of the cam roller spherical bearing. Freedom of movement was verified following reassembly with no instances of binding throughout the full range of motion.
The reassembly of the linkage was verified to be in accordance with its design configuration.
Basis Condition report CR537862 documented the "Terry Turbine tripped on over speed" that occurred on January 23, 2014. Review of the surveillance data identified that the valve stem of the Terry Turbine Main Steam Supply Control Valve did not receive sufficient force to properly modulate the steam supply. As a result, the control valve did not adequately control the turbine speed resulting in the over speed trip.
Complex troubleshooting was performed using a Terry Turbine Tripped on Over speed Fault Tree which identifies the following possible causes for the over speed trip:
- 1. AOV Steam Supply stroke rate
- 2. Moisture in main the steam supply
- 3. Trip Valve (3MSS*MSV5) performance
- 4. Turbine operation
- 5. Work practices
- 6. Pump operation
- 7. Procedure weaknesses
- 8. Human Error
- 9. Linkage performance
- 10. Control Valve performance
- 11. Design weaknesses
- 12. Governor performance The subject fault tree evaluates the twelve (12) possible causes of over speed trip.
Items one (1) - eight (8), ten (10) and eleven (11) are determined as "not a factor" and the basis is documented on the subject fault tree. Item 2, moisture in the main steam supply was identified as a factor in the previous over speed trips on November 4, 2013 and December 18, 2013. Item 2 (moisture) is not considered a contributor to the January 23, 2014 over speed trip as the compensatory measures established as a result of the previous trips were still in place. Video taken during the January 23, 2014 test also showed a reduction in the amount of condensate being ejected from the valve packing area during TDAFW pump startup.
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 5 of 18 Prior to the commencement of the January 23, 2014 test, a strain gauge was installed to measure the force being applied to the actuator control valve stem from the linkage of 3MSS*MCV5 (Terry Turbine Main Steam Control Valve). Data collected via the strain gauge indicated insufficient force being transferred through the linkage. Since there was insufficient force on the stem to properly operate the control valve, possible causes 9 (linkage performance) and 12 (governor performance) were selected for further evaluation.
The steam supply to the Terry Turbine results in Terry Turbine rotor rotation, which turns a spline within the governor. This rotational force provides hydraulic pressure to generate linear governor output. The linear output controls the turbine control valve position; thereby controlling Terry Turbine speed. Governor output is transmitted to the control valve stem via linkage. Consequently, the low force measured within the control valve stem was the result of either low output from the governor or a loss of force measured in the transfer from the governor to the stem (i.e., within the linkage).
Low Governor Output To address the low governor output concern, the governor was replaced with a newly refurbished governor. This alleviates any concerns with the governor. Potential causes of low governor output are:
" Incorrect oil used within the governor
" Contaminants within the oil
" Governor internal failures Oil samples were taken and sent to laboratory for analysis with testing to be expedited. This will determine if there were contaminants present or if the incorrect oil was used. The replaced governor will be sent to the governor supplier ESI for refurbishment. Prior to refurbishment the governor will be inspected and tested to verify proper operation (i.e., expected output).
Linkage Inspection (e.g., high drag, binding)
Troubleshooting included a "pull test" of the linkage. Three performances of this test resulted in recorded forces (i.e., 19.7, 24.5, and 23.3 pounds) less than the maximum acceptance criteria of 26 pounds. However, during full stroking of the linkage the cam-plate linkage Heim joint was binding at the full open position. Visual inspection of this linkage identified the Heim joint was installed backwards (i.e., threaded end installed on bottom versus on top) and corresponding potential binding imprints on the associated clevis. The Heim joint was reinstalled to the correct orientation.
Afterwards, freedom of linkage movement was verified subsequent to establishing the correct orientation with no signs of binding throughout the full movement. Pull tests performed following linkage adjustment and control valve maintenance resulted in as left values of 13.3, 12.8, 13.2, and 12.9 pounds indicating a reduction in resistance.
Subsequent to the pull test, the linkage was further adjusted to set up correct valve
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 6 of 18 stroke and seating. After the linkage adjustment, three additional pull tests were performed to demonstrate continued freedom of movement. The results from that test were 13.6, 12.9, and 13.3 pounds. The consistent repeatability of the pull test results are considered indicative of effective resolution of linkage binding deficiencies.
Security concerns related information is included in Section J.
- e. Detail the proposed course of action to resolve the situation, so enforcement discretion is no longer required.
The actions to replace the governor, rebuild the control valve, and rebuild the control valve linkage to the governor have been completed. The TDAFW pump has been run for some operational checks and governor grooming with satisfactory results. The initial operational test identified the need to replace the associated discharge relief valve. The final test sequence will be conducted after the relief valve repair and testing and when the turbine TDAFW pump has returned to standby conditions. A full flow test will be performed to satisfy the In Service Testing (IST) retest requirements and validate proper governor operation and control after the maintenance activity. If the results of this test indicate that additional tuning of the governor is required then the TDAFW pump will be shutdown and restarted in a maintenance mode to make the necessary adjustments. This process of retesting and adjusting is iterative and may involve multiple cycles to obtain satisfactory performance. Each cycle takes approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> to implement. Additionally a quarterly operational test, time response testing, and over speed testing will be performed. Successful execution of the adjustment and retest sequence will lead to acceptable turbine performance and will result in an operable TDAFW pump at which time enforcement discretion will no longer be necessary.
- f. Explain that the resolution itself will not result in a different, unnecessary transient.
Repairs of the TDAFW pump will not result in a different, unnecessary transient as the TDAFW pump is not an initiator of any event.
Following repairs, a full flow/operational readiness test of the TDAFW pump will be performed in Mode 1 to demonstrate operability. This test will be conducted as an Infrequently Conducted or Complex Evolution. A safety analysis review of this testing has concluded that there is no more than a minimal increase in the consequences of an accident previously evaluated.
- g. Explain that the licensee did not have time to process an emergency license amendment, or that a license amendment is not needed.
A license amendment is not needed since this is a one-time request to allow repair and testing of the TDAFW pump. No permanent change to the operating license or the TSs is required.
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 7 of 18
- h. Describe the condition and operational status of the plant, including safety-related equipment out of service or otherwise inoperable, and nonsafety-related equipment that is degraded or out of service that may have risk significance and that may increase the probability of a plant transient or may complicate the recovery from a transient or may be used to mitigate the condition.
At the time the enforcement discretion was verbally requested on January 26, 2014, MPS3 was at 100% power in Mode 1. On-line risk was Green. MPS3 was in TS Action Statement 3.7.1.2. Action c., Auxiliary Feedwater System.
Additional Protected Equipment:
- 'B' and 'C' Reactor Plant Chillers and 'A' and 'B' Containment Vacuum Pumps (for
'A' CDS Chiller overhaul)
" 'B' Emergency Diesel Generator Fuel Oil Transfer Pump ('D' Fuel Oil Transfer Pump breaker maintenance)
" 'B' Circulating Water Pump and VFD, 'B' Screen Wash Pump ('A' Circulating Water Bay Outage)
- 'B' Control Building Chiller and support equipment ('A' Control building chiller outage)
- 'A' and 'B' EDGs and both MDAFW pumps (TDAFW pump outage). Per OP-MP-601, Protected Equipment, when 3FWA*P2 is Out of Service:
o Place Protected Equipment Barrier around 3FWA*P1A.
o Place Protected Equipment Sign on Breaker 34C1 6-2.
o Place Protected Equipment Barrier around 3FWA*P1 B.
o Place Protected Equipment Sign on Breaker 34D1 5-2.
o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-1.
o Place Protected Equipment Sign on or Stanchion adjacent to the A train door EG-24-3.
o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCA.
o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-2.
o Place Protected Equipment Sign on or Stanchion adjacent to the B train door EG-24-4.
o Place Protected Equipment Tag on or Stanchion adjacent to EDG Sequencer 3RPS*PNLESCB.
" Protect all safety related DC and AC sources in both trains (TSs 3.8.2.1 and 3.8.3.1).
Time to Spent Fuel Pool heating to 200°F on loss of all cooling: - 92 hours0.00106 days <br />0.0256 hours <br />1.521164e-4 weeks <br />3.5006e-5 months <br /> Current Spent Fuel Pool Temperature: 92.0°F
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 8 of 18 Active LCO Actions requiring shutdown within 7 days:
- T/S 3.7.1.2 action c. - 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for TDAFW Pump Inoperable (tripped on over speed) (expires 1/26/14 at 13:50)
Abnormal conditions / Key equipment out of service (OOS):
" TDAFW Pump tripped on over speed during testing
" 480V non-vital bus 32H intermittent Ground on 'C' Phase
" 3SSR*RE08 non-functional due to 3SSR*CTV19B out of service
" Non-safety related Battery 6 variable ground The PRA condition is GREEN and it is expected to be GREEN for the duration of the TDAFW pump outage except for a brief period during TDAFW Pump Full Flow testing where it will be YELLOW. Risk significant equipment which is not or will not be available:
" 'D' Steam Line to TDAFW Pump
" 'D' Diesel Fuel Oil Transfer Pump
- 'A' Circ Bay
- TDAFW Pump Core Damage Frequency (CDF) Allowed Condition Time (ACT) is 100.2 days and Large Early Release Frequency (LERF) ACT is 159.6 days.
- i. Request a specific time period for the NOED, including a justification for the duration of the noncompliance. The licensee shall include information that shows its proposed course of action has a high likelihood of being completed within the proposed NOED period. The licensee must show the requested time for the NOED is directly related to the time to resolve the situation.
This enforcement discretion is requested until 0150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> on January 28, 2014, for TS 3.7.1.2 - Auxiliary Feedwater System.
The request for enforcement discretion was made to avoid an unnecessary plant transient as a result of compliance with TS 3.7.1.2 action c., by allowing an extension of the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AOT. The additional 36 hour4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> duration is needed to support repair and testing activities which are in progress.
- j. Detail and explain compensatory actions the plant has both taken and will take to reduce the risk associated with the specified configuration. All compensatory actions must be completed before the NOED CT begins.
Compensatory measures used to reduce plant vulnerabilities shall focus on both event mitigation and initiating event likelihood. The objectives are to achieve the following:
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 9 of 18
- 1. Reduce the likelihood of initiating events, and
- 2. Reduce the likelihood of the unavailability of trains redundant to equipment that is out-of-service during the period of enforcement discretion, and
- 3. Increase the likelihood of successful operator recovery actions in response to initiating events.
An example is a situation in which a motor-driven auxiliary feedwater (AFW) pump has failed and risk insights have established that plant transient initiators may be risk-significant events because the plant has no primary feed-and-bleed capability and only limited secondary feed capability is available. As a compensatory measure during the period of enforcement discretion, the licensee may defer non-essential surveillances or other maintenance activities in which human error contributes to the likelihood of a plant trip and subsequent demand on the remaining AFW pumps. Another example of appropriate compensatory measures would be actions that increase the likelihood of success in the manual alignment or start-up of equipment in response to an initiating event (e.g., positioning operators locally at equipment, "just-in-time training", or additional contingency plans).
The compensatory actions listed below are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events. To reduce the risk during the duration of the NOED, DNC will take the following compensatory actions:
Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components for areas affected when TDAFW pump is OOS:
o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are:
" CB-1, Control Building West Switchgear Room - El. 4' 6"
" CB-2, Control Building East Switchgear Room - El. 4' 6"
" CB-8, Control Building Cable Spreading Area - El. 24' 6"
" CB-9, Control Building Control Room - El. 47' 6" SCR- 1 .rC frnl Ri lrlinn Inftrllmant I nk-k Pnnm I Indlr flnnr 1=1 46' 6") and Rack Room - El. 47' 6" U SB-2, Service Bldg North Cable Tunnel - El. 4' 6" U SB-3, Service Bldg South Cable Tunnel - El. 4' 6" U
ESF-1, ESF Bldg South Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6"
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 10 of 18
" ESF-2, ESF Bldg North Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6"
" ESF-4, ESF Bldg East Piping Area - El. 4' 6"
" ESF-7, ESF Bldg Mechanical Equipment Room C - 36' 6" and ESF Bldg Refueling Water Recirc Pumps Area - 21' 6"
" ESF-8, ESF Bldg North MDAFW Pump Area - El. 24' 6"
" ESF-9, ESF Bldg South MDAFW Pump Area - El. 24' 6" and ESF Bldg Mechanical Equipment Room D - El. 36' 6"
- Include area AS-1 D, Auxiliary Building West Floor Area - El. 24' 6" in the implementation of (a)(4) fire risk management actions.
" An operator is continuously staged at the station blackout (SBO) Diesel Generator (DG)
- No planned unit transients, other than those described in the NOED for 4%
downpower and associated full flow test, will be allowed for the duration of the NOED
- No planned switchyard maintenance
" Protect the motor-driven auxiliary feedwater trains, main feedwater system, and condensate system
- Removal of any of the components either due to scheduled or corrective maintenance will be monitored via the Risk Monitor (EOOS) and the MRule (a)(4) process
" The Outage Control Center will be staffed 24/7 until the TDAFW pump is operable and the TS action has been exited.
- k. Discuss the status and potential challenges to offsite and onsite power sources, including any current or planned maintenance in the distribution system and any current or planned maintenance to the emergency diesel generators. The licensee must identify any specific transmission line configurations that must be maintained to ensure the availability of the grid for safe operation of the plant.
Currently, MPS3 has no offsite or onsite power sources out of service, nor are any planned to be taken out of service during the time period when the proposed NOED will be used. Both MPS3 Emergency Diesel Generators, along with the SBO Diesel Generator, are available with no planned maintenance activities for the proposed NOED time period.
- 1. Include the safety basis for the request and an evaluation of the safety significance and licensee should address the quantitative and qualitative aspects noted below. The numerical guidance for acceptance was established to augment qualitative arguments that continued operation of the plant during the period of enforcement discretion will not cause risk to exceed the level determined acceptable during normal work controls and, therefore, there is no net increase in radiological risk to the public. For licensee provided quantitative risk analysis, the licensee shall provide the effects on LERF. The following information should be provided to support this evaluation:
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 11 of 18
- 1. Use the zero maintenance PRA model to establish the plant's baseline risk and the estimated risk increase associated with the period of enforcement discretion. For the plant-specific configuration the plant intends to operate in during the period of enforcement discretion, the ICCDP and ICLERP should be quantified and compared with guidance thresholds of less than or equal to an ICCDP of 5E-7 and an ICLERP of 5E-8. These numerical guidance values are not pass-fail criteria. For the degraded case with the subject equipment out of service, the model should reflect, as best as possible, current equipment unavailability states (i.e., if other equipment is unavailable because of T&M, this should also be reflected in the analysis). This risk calculation should not be limited to the specific TS relief in question, but rather, the total risk of continued operation for the specific configuration of the plant.
The MPS3 zero-maintenance internal events risk monitor PRA model, M310R02, was used to estimate the impact on plant risk. The risk impact is associated with the TDAFW pump out-of-service for the duration of the enforcement discretion.
ICCDP and ICLERP were calculated using the following equations:
ICCDP = [Conditional CDF for TDAFW Out-of-Service - Baseline CDF] * [TDAFW Pump enforcement discretion outage duration]
ICLERP = [Conditional LERF for TDAFW Out-of-Service - Baseline LERF] *
[TDAFW Pump enforcement discretion outage duration]
The requested period of enforcement discretion was assumed to be 3 days beyond the technical specification allowed outage time of 3 days (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />). The incremental risk associated with this period of operation is:
ICCDP = [6.08E-06/yr - 2.47E-06/yr] * [1 yr/365 days
- 3 days] = 2.97E-08 ICLERP = [2.65E-07/yr - 3.65E-08/yr] * [1 yr/365 days
- 3 days] = 1.88E-09 The above risk assessment only addresses test and maintenance activities for the TDAFW for the duration of the NOED. All other test, maintenance and environmental conditions are assumed to be in their nominal condition. Any deviations will be addressed via the Risk Monitor (EOOS) and the MRule (a)(4) process.
These results are below the NRC Inspection Manual, Chapter 0410 limits of 5E-7 for ICCDP and 5E-8 for ICLERP.
- 2. Discuss the dominant risk contributors (cut sets or sequences or both) and summarize the risk insights for the plant-specific configuration the plant intends to operate in during the period of enforcement discretion. This discussion should focus primarily on risk contributors that have changed
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 12 of 18 (increased or decreased) from the baseline model because of the degraded condition and resultant compensatory measures, if any.
The dominant sequences for Level 1 CDF with the TDAFW Pump unavailable are associated with loss of offsite power, loss of a 4160V AC bus, and loss of a DC bus initiating events. This pump is also important for mitigating several internal flooding scenarios. The LERF dominant sequences, in addition to the CDF dominant sequences, include mitigation of Steam Generator Tube Rupture (SGTR) initiating events. The important mitigating system is the motor-driven auxiliary feedwater pumps. The important operator action is re-establishing main feedwater and condensate to the steam generators.
Due to the risk implications with the TDAFW pump unavailable, no maintenance will be planned for the offsite power supply to the plant, the onsite electrical power sources, motor-driven auxiliary feedwater trains, main feedwater system, and condensate system.
- 3. Discuss how the compensatory measures are accounted for in the PRA.
These modeled compensatory measures should be correlated, as applicable, to the dominant PRA sequences identified in items 1 and 2 above. In addition, other measures not directly related to the out-of-service equipment may also be implemented to reduce overall plant risk and, as such, should be explained. Compensatory measures that cannot be modeled in the PRA shall be assessed qualitatively.
The following compensatory measures will be taken:
Implement the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1, Fire Related Safe Shutdown Components:
o Review existing transient combustibles permits for the affected areas o Review existing ignition source permits for the affected areas o Perform an area walkdown of the affected areas o Evaluate all work requiring transient combustibles, hot work, or racking of breakers in the affected areas o Brief the shift operators and the fire brigade lead on the significance of a fire in the affected areas o Affected areas to be managed when the TDAFW pump is disabled are:
" CB-1, Control Building West Switchgear Room - El. 4' 6"
" CB-2, Control Building East Switchgear Room - El. 4' 6"
" CB-8, Control Building Cable Spreading Area - El. 24' 6"
" CB-9, Control Building Control Room - El. 47' 6"
" CB-11, Control Building Instrument Rack Room Under floor - (-El.
46' 6") and Rack Room - El. 47' 6"
" SB-2, Service Bldg North Cable Tunnel - El. 4' 6"
" SB-3, Service Bldg South Cable Tunnel - El. 4' 6"
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 13 of 18
" ESF-1, ESF Bldg South Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6"
" ESF-2, ESF Bldg North Cntmt Recirc Cooler Cub - El. -34' 9" to 36' 6"
" ESF-4, ESF Bldg East Piping Area - El. 4' 6"
" ESF-7, ESF Bldg Mechanical Equipment Room C -El- 36' 6" and ESF Bldg Refueling Water Recirc Pumps Area -El- 21' 6"
" ESF-8, ESF Bldg North MDAFW Pump Area - El. 24' 6"
" ESF-9, ESF Bldg South MDAFW Pump Area - El. 24' 6" and ESF Bldg Mechanical Equipment Room D -El- 36' 6"
" Include area AS-1 D, Auxiliary Building West Floor Area - El. 24' 6" in the implementation of (a)(4) fire risk management actions.
" An operator is continuously staged at the station blackout (SBO) diesel generator (DG) in accordance with Security Risk requirements.
" No planned unit transients, other than those described in the NOED for 4%
downpower and associated full flow test, will be allowed for the duration of the NOED
- No planned switchyard maintenance
- Protect the motor-driven auxiliary feedwater trains, main feedwater system, and condensate system
- Removal of any of the components either due to scheduled or corrective maintenance will be monitored via the Risk Monitor (EOOS) and the MRule (a)(4) process None of the compensatory measures listed above are directly accounted for in the PRA calculation of ICCDP and ICLERP. The actions are intended to increase operator awareness of plant conditions, to reduce the likelihood of losing redundant trains, and to reduce the likelihood and consequences of initiating events.
- 4. Discuss the "extent of condition" of the failed or unavailable component(s) to other trains or divisions of equipment and the adjustments, if any, which were made to the related PRA common cause factors to account for potential increases in their failure probabilities. The method used to determine the extent of condition shall be discussed. It is recognized that a formal root cause or apparent cause is not required because of the limited time available in determining the acceptability of a requested NOED. However, a discussion of the likely cause shall be provided with an associated discussion of the potential for common cause failure.
The extent of condition is limited to the TDAFW pump since the failure mechanism is associated with the turbine speed control function of the pump. No other equipment in the AFW common cause component group shares this design for motive force. As a result, no adjustments have been made to the PRA to account for common cause factor and potential increases in common cause failure probabilities. Additionally, the MPS3 emergency diesel generators use control systems which are sufficiently different from the one used with the TDAFW pump
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 14 of 18 (i.e. Woodward EGB versus Woodward PGG) such that the extent of condition is not applicable to the MPS3 emergency diesel generators. The MPS3 emergency diesel generators have been successfully tested and operated with no similar adverse conditions.
- 5. Discuss external event risk for the specified plant configuration. An example of external event risk is a situation in which a reactor core isolation cooling (RCIC) pump has failed and a review of the licensee's Individual Plant Examination of External Events or full-scope PRA model identifies that the RCIC pump is used to mitigate certain fire scenarios. Action may be taken to reduce fire ignition frequency in the affected areas and to reduce human error associated with time-critical operator actions in response to such scenarios, and to ensure fire protective and corrective measures have been taken.
The MPS3 PRA is a level 1 and 2 (LERF) model that includes internal events and internal floods. For external events (e.g., fire, seismic, external floods, high winds) the IPEEE is used for risk insights.
Fire The MPS3 internal events PRA does not include a fire model. Therefore, the fire risk is qualitatively assessed using the IPEEE. The IPEEE fire risk quantified a CDF impact by combining the frequency of fires and the probability of detection/suppression failure with the remaining safety function random failures. A systematic approach was used to identify critical fire areas where fires could fail safety functions and pose an increased risk of core damage if other safety functions are unavailable. The CDF due to fires is 4.8E-6/yr, with the dominant risk being fires in the cable spreading room, switchgear rooms, control room, and auxiliary building.
To mitigate the potential impact to fire risk, DNC will implement compensatory measures in accordance with the (a)(4) fire risk management actions in the Technical Requirements Manual (TRM) Section 7.4.1. The compensatory actions include the affected areas, cable spreading room (CB-8), switchgear rooms (CB-1 and CB-2), and control room (CB-9). Though the TRM does not require fire risk management actions for the Auxiliary Building location containing the Charging and Reactor Building Component Cooling Water Pumps, fire zone AS-1 D has been added to the compensatory measures based on risk insights from the IPEEE.
Seismic The MPS3 internal events PRA does not include a seismic model. The IPEEE quantified a CDF impact by combining the seismic hazard frequencies with the fragilities of critical structures and components and the safety function random failures. The CDF due to seismic events is 9.1E-06/yr, with the dominant risk being seismic events that result in a loss of offsite power and failure of the
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 15 of 18 emergency diesel generator enclosures, or collapse of the control building. A review of the cutsets associated with loss of offsite power and early core melt (contributes 63% Seismic CDF) found that random failure of the auxiliary feedwater system does not significantly contribute to the seismic risk. Therefore, this NOED will not significantly impact the seismic risk.
High Winds, External Floods, and Other Events The risk of other external events such as high winds, external flooding, aircraft accidents, hazardous materials, and turbine missiles was assessed in the MPS3 IPEEE. The IPEEE assessments concluded that the risk of these accidents is negligible primarily due to the low frequency of occurrence that would cause damage to mitigating systems. For example, reinforced concrete houses provide the applicable safety systems missile protection during high winds. Note the potential for high winds is covered under section n, which provides a discussion on forecasted weather.
- m. Demonstrate that the NOED condition, along with any compensatory measures, will not result in more than a minimal increase in radiological risk, either in a quantitative assessment that risk will be within the normal work control levels (ICCDP less than or equal to 5E-7 and/or ICLERP less than or equal to 5E-8) or in a defensible qualitative manner.
The PRA evaluation calculates the change in risk associated with an assumed 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> NOED for TDAFW Pump unavailability. The ICCDP is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP is 1.88E-09, which is below the 5E-8 threshold. The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP.
- n. Discuss forecasted weather and pandemic conditions for the requested NOED period and any plant vulnerabilities related to weather or pandemic conditions.
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 16 of 18 Daily Forecast for GROTON, CT (KGON)
DSun Man ; Tue VWd Thu ; I I "
- Mon E.
1/26 !1F27 Dat 1128 129 1 Fr/31 Sat2/1 'Sun 212 Mon2/3 Tue2A4 Wed225,Thu2/6 Fri 2/7 Sat2/8 Sun2/9 2110 WeatherCondion Afternoon 0 -
Sn*w Weathr Rn .non ,, Partly Mostly Afternoon Partly Partly Flurries Snow Partly Snow Mostly Snow . Partly Weter S ow ansunnSnn . . Cloudy uyoudyCloudy IFlurriesCluylodLieyieya r Cloudy Cloudy Likely Likely Cloudy Likely Cloudy: Likely Cloudy P.ossibl Temperature *F) 17/31 22143 11(23 11129 15/33 25M40 26/42 29/42 26/35 25/38 23/46 22/34 20/31 1 18/31 19/31 17/32 (LoIII)
Feels Like (F) 2/22 12127 -2118 0/19 6/27 16/33 20/38 21/37 18/28 16/32 13/40 11/25 8/22 6122 7(21 5n24 (Lo/14)
Wet Bulb (*F) ',
(Le/l) 13/29 17/43 8/17 9/22 12/28 24/33 25/41 27/42 24/32 25134 22/41 20/28 19/28 . 17/26 18/28 16/2B Dew Polnt (*F) 11 22 -3 1 2 11 22 26 28 24 27 22 18 20 156 19 20 Humldity(*A 57 60 33 39 54 60 66 71 78 822 53 57 76 .62 7573 Wind Speed (mph) 13 11 7 9 7 9 5 6 6 8 10 I 10
- 9 I 11 Preclpltatdon 36 60 5 '0 60, 7 5 Precipitation Rain S 1/4 S:<1/4 I S:1-3 1S:144-1N S1-3 Amount Trace R None None None I None None No ne ,L:.25 None L0 ne N1ne (Raln:ln.Snow:ln.) 0.04 '0 L L .:'.06 Evapotransplration Unchesiday) 0.06 0.07 1 0.05 0.06 0.05 r 0.05 0.04 0.04 0.03 0.03 0.08 0.05 003 0.04 0.03 0.03 There are no additional plant vulnerabilities related to the weather conditions for the duration of the NOED.
- o. Include the basis for the licensee's conclusion the noncompliance will not create undue risk to public health and safety.
The request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., by allowing an extension of the allowed outage time (AOT) for an additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for an inoperable auxiliary feedwater pump, does not result in a significant hazards consideration as defined in 10 CFR 50.92. Specifically, the proposed enforcement discretion does not:
- Involve a significant increase in the probability or consequences of an accident previously evaluated. The ICCDP, based on an assumed additional 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AOT, is 2.97E-08, which is below the NRC Inspection Manual, Chapter 0410 limit of 5E-7. The ICLERP, based on an assumed additional 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> AOT, is 1.88E-09, which is below the 5E-8 threshold. The risk impact is considered negligible and consequently, the NOED poses no net increase in risk beyond normal work control levels. As noted previously, any compensatory measures are not directly accounted for in the PRA calculation of ICCDP and ICLERP.
Allowing an additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> for the repairs associated with the TDAFW pump is acceptable since the AFW system remains capable of performing its intended function. During the extended maintenance and test period, the compensatory actions identified in section J. will be implemented. Therefore, the consequences of accidents related to or dependent on AFW system operation will not be significantly affected.
- Create the possibility of a new or different kind of accident from any accident previously evaluated. There are no new failure modes or mechanisms associated with plant operation for an extended period to perform maintenance and testing on the TDAFW pump. Extended operation with an inoperable TDAFW pump does not involve any modification in the operational limits or
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 17 of 18 physical design of the involved systems. Therefore, there are no new accident precursors generated due to the extended maintenance and testing period.
Involve a significant reduction in a margin of safety. Plant operation for an additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> with the inoperable TDAFW pump does not adversely affect the margin of safety. During the extended maintenance and testing period the AFW system remains capable of performing its intended safety function. The compensatory measures identified in section J. will remain in effect for the time period when the proposed NOED will be used to assure safety margins are maintained.
- p. Include the basis for the licensee's conclusion the noncompliance will not involve adverse consequences to the environment.
The request for enforcement discretion does not change requirements with respect to the installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement.
Specifically, the request for enforcement discretion to avoid an unnecessary plant shutdown as a result of compliance with TS 3.7.1.2 ACTION c., does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.
Accordingly, the request for enforcement discretion meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), an environmental assessment for the request is not required.
- q. Include a statement that the facility organization that normally reviews safety issues has approved the request (Plant Onsite Review Committee, or its equivalent).
The Facility Safety Review Committee has reviewed and concurs with this request.
- r. Make a verbal commitment that the licensee will submit the written NOED request within 2 working days and a follow-up license amendment request within 4 working days following the staff's verbal granting of the NOED. NRC's granting of a NOED means that exigent circumstances exist. However, the licensee's amendment request must describe and justify any exigent circumstances (see 10 CFR 50.91(a)(6)). If the staff agrees during the conference call that a follow-up amendment request is not required, the licensee shall state this in the written NOED request. If the licensee intends to propose a temporary amendment, the licensee's amendment request shall include justification for the temporary nature of the request.
A license amendment is not being requested. The requested NOED represents a request for enforcement discretion for a temporary, specific period of time in which MPS3 seeks to extend the AOT for TS ACTION 3.7.2.1 .c. for an additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> in order to allow completion of repairs, and restore the TDAFW PUMP to OPERABLE status.
Serial No.14-043 Docket No. 50-423 MPS3 AFW Request for Enforcement Discretion Attachment 1, Page 18 of 18
- s. In addition to items a thru r above, the licensee must provide the following information for a natural event NOED:
- 1. List the name, organization, and telephone number of the official in the government or independent entity who made the emergency determination, if applicable. If deemed necessary, the staff may contact the appropriate official to independently verify the information the licensee provided before making a NOED determination.
- 2. Include details of the basis and nature of the emergency including, but not limited to, its effect on the following:
(a.) on-site and off-site emergency preparedness, (b.) plant and site ingress and egress, (c.) off-site and on-site power sources, (d.) plant security, (e.) grid stability, and (f.) actions taken to avert or alleviate the emergency situation (e.g.,
coordinating with other utilities and the load dispatcher organization for buying additional power or for cycling loads, or shedding interruptible industrial or non-emergency loads).
- 3. Identify and discuss the potential consequences of compliance with existing license requirements (e.g., plant trip, controlled shutdown).
- 4. Discuss the potential adverse effects on public health and safety from enforcing compliance with specific license requirements during the emergency.
- 5. Discuss the impact of the emergency on plant safety, including any limitations of the UHS.
6 For a grid instability NOED, assure the NRC that all reasonable opportunities for purchasing replacement power have been exhausted, and the NOED shall not last any longer than replacement power becomes available, if applicable.
Not applicable as this is not a natural event NOED.