Text

Proposed Tech Specs Re Changes That Allow One of Two Svc Water Loops to Be Isolated from Component Cooling Water Heat Exchangers During Power Operationin Order to Refurbish Isolated Svc Water Headers
	ML20087G347
Person / Time
Site:	North Anna
Issue date:	03/30/1995
From:	; VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	;
Shared Package
ML20087G346	List: ML20087G342; ML20087G347;
References
	NUDOCS 9504040160
	Download: ML20087G347 (11)
	v • d • e

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e ATTACHMENT 2 l

5 PROPOSED TECHNICAL SPECIFICATIONS CHANGES NORTH ANNA UNITS 1 AND 2 t

VIRGINIA ELECTRIC AND POWER COMPANY 9504040160 950330

.PLR ADOCK 05000338 P PDR

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I PLANT SYSTEMS 3/4.7.3 COMPONENT COOLING WATER SYSTEM 3/4.7.3.1 COMPONENT COOLING WATER SUBSYSTEM - OPERATING l LIMITING CONDITION FOR OPERATION 3.7.3.1 Three component cooling water subsystems (shared with Unit 2) shall be OPERABLE * ** with each subsystem consisting of: l

a. One OPERABLE component cooling water pump and,

b. One OPERABLE component cooling water heat exchanger.

APPLICAlllLIIY; Either Unit in MODES 1,2,3 or 4.

ACTION:

a. With one required component cooling water subsystem inoperable, return the component cooling subsystem to OPERABLE status within the next 7 days, or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

b. With two required component cooling water subsystems inoperable, place both units in HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months , and within the next hour, initiate actions to place both units in COLD SHUTDOWN and continue until COLD SHUTDOWN is achieved.

c. With no component cooling water available to supply the residual heat removal heat exchangers to cool the units, place both units in HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and remain in HOT SHUTDOWN until alternate means of decay heat removal can be implemented. Continue actions until both units are in COLD SHUTDOWN.

For the purpose of this Technical Specification, each subsystem is considered OPERABLE if it is operating or ifit can be placed in service from a standby condition by manually unisolating a standby heat exchanger and/or manually starting a standby pump.

- For the purpose of service water system upgrades associated with the supply and return piping to/from the component cooling water heat exchangers (CCHXs), the component cooling water subsystems shall be considered OPERABLE with only one service water loop to/from the CCHXs, provided all other requirements in this specification are met.

This condition is permitted two times only (once for each SW loop) for a duration of up to 49 '.ays each. During each period of operation with only one SW loop available to/from the CCHXs, the provisions of Specification 3.0.4 are not applicable. Upon completion of the work associated with the second 494ay period, this footnote will na longer be applicable.

NORTH ANNA - UNIT 1 3/4 7-17 Amendment No. 449,

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. PLANT SYSTEMS 3/4.7.3 ' COMPONENT COOLING WATER SYSTEM 3/4.7.3.1 COMPONENT COOLING WATER SUBSYSTEM - OPER ATING !

SURVEILLANCE REQUIREMENTS , 4.7.3.1 Three component cooling water subsystems shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or automatic) servicing in the flow path of the residual heat removal system that is not locked, scaled, or otherwise secured in position, is in its correct position.

b. Each component cooling water pump shall be tested in accordance with l Specification 4.0.5.

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NORTH ANNA - UNIT 1 3/4 7-17a Amendment No.

,' . PLANT SYSTEMS 1

3/4.7.3 COMPONENT COOLING WATER SYSTEM 3/4.7.3.2 COMPONENT COOLING WATER SUBSYSTEM - SHUTDOWN LIMITING CONDITION FOR OPERATION 3.7.3.2 Two component cooling water subsystems (shared with Unit 2) shall be OPERABLE

with each subsystem consisting of: -

a. One OPERABLE component cooling water pump and,

b. One OPERABLE component cooling water heat exchanger.

AEPLICABILITY: Both Units in MODES 5 or 6.

ACTION:

With one required component cooling water subsystem inoperable,immediately suspend all operations involving an increase in the reactor decay heat load or a reduction in boron concentration of the Reactor Coolant System.

SURVEILLANCE REQUIREMENTS

. 4.7.3.2 At least two component cooling water subsystems shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or automatic) the flow path of the residual heat removal system that is not locked, sealed, or otherwise secured in position, is in its correct position.

b. Each component cooling water pump shall be tested in accordance with Specification 4.0.5.

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For the purposes of this Technical Specification, each subsystem is considered OPERABLE if it is operating or if it can be placed in service from a standby condition by manually unisolating a standby heat exchanger and/or manually starting a standby pump.

NORTH ANNA - UNIT 1 3/4 7-17b Amendment No. 4-59, l

PLANT SYSTEMS 3/4.7.4 SERVICE WATER SYSTEM 3/4.7.4.1 SERVICE WATER SYSTEM -OPERATING LIMITING CONDITION FOR OPERATION 3.7.4.1 Two service water loops (shared with Unit 2) shall be OPERABLE with each loop consisting of:

a. Two OPERABLE service water pumps (excluding auxiliary service water pumps) with their associated normal and emergency power supplies,

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b. An OPERABLE flow path capable of providing cooling for OPERABLE plant components and transferring heat to the service water reservoir.* l APPLICABILITY: Either Unit in MODES 1,2,3 or 4.

ACTION:

a. With one service water pump inoperable, within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months throttle component cooling water heat exchanger flows, in accordance with approved operating procedures, to ensure the remaining service water pumps are capable of providing adequate flow to the recirculation spray heat exchangers. The provisions of Specification 3.0.4 am not applicable once component cooling heat exchangers flows are throttled.

b. With two service water pumps inoperable, perform ACTION 3.7.4.1.a within I hour and mstore at least one service water pump to OPERABLE status within

, 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in If0T STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

c. With one service water loop incperable, except as provided in ACTION 3.7.4.1.a.

restore the inoperable loop to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

For the purpose of service water system upgrades associated with the supply and return piping to/from the component cooling water heat exchangers (CCHXs), one of the two service water (SW) loops is pennitted to temporarily bypass the CCHXs, provided all other requirements in this specification are met. This condition is permitted two times only (once for each SW loop) for a duration of up to 49 days each. During each period of operation with only one SW loop available to/from the CCHXs, four out of four SW pumps (excluding the auxiliary SW pumps) shall remain OPERABLE. With one SW pump inoperable, work may continue provided actions are taken to either restore the pump to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months or restore both SW headers to/from the CCHXs to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

During each period of operation with only one SW loop available to/from the CCHXs, ,

the automatic closure feature of the SW valves servicing the CCHXs shall be defeated l to ensum SW flow to the CCHXs is not interrupted. During each period of operation with only one SW loop available to/from the CCHXs, the provisions of Specification 3.0.4 are not applicable, provided two SW loops are capable of providing cooling for the other OPERABLE plant components. Upon completion of the work associated with the second 49-day period, this footnote will no longer be applicable.

NORTH ANNA - UNIT 1 3/4 7-18 Amendment No. 3,57,70,152, 4 63,

. PL, ANT SYSTEMS 3/4.7.4 SERVICE WATER SYSTEM 3/4.7.4,1 SERVICE WATER SYSTEM - OPERATINO LIMITING CONDITION FOR OPERATION

d. The allowable time that one of the two service water loops can be inoperable as specified in ACTION 3.7.4.1.c may be extended beyond 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months up to 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months as part of service water system upgrades

provided 3 out of 4 service water pumps (the thini pumps does not requim auto start capability) and 2 out of 2 auxiliary service water pumps have been OPERABLE since initial entry into the action statement and remain OPERABLE during the extended action statement or be in at ,

least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within ,

the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

e. With two service water loops inoperable for reasons other than described in ACTION 3.7.4.1.b, place both units in HOT SHUTDOWN within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and within the following hour, initiate actions to place both units in COLD SHUTDOWN and continue actions until both units are in COLD SHUTDOWN.

SURVEILLANCE REQUIREMENTS 4.7.4.1 At least two service water loops shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or automatic) servicing safety mlated equipment that is not locked, sealed, or otherwise secured in position, is in its correct position.

b. At least once per 6 months by measurement of the movement of the pumphouse and wing walls.

c. At least once per 18 months during shutdown by:

1. Verifying that each automatic valve servicing safety related equipment actuates to its correct position on an actual or simulated safety injection signal.

2. Verifying that each automatic service water valve actuates to its correct position on an actual or simulated containment high-high signal.

d. Each service water pump will be tested in accordance with Specification 4.0.5.

Isolation of one service water loop for up to 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months is permitted only as part of service water system upgrades. System upgrades include modification and maintenance activities ;

associated with the installation of new discharge headers and spray arrays, mechanical and l chemical cleaning of service water piping and valves, pipe repair and replacement, valve repair and replacement, installation of corrosion mitigation measures and inspection of and ;

mpairs to buried piping interior coatings and pump or valve house components.

NORTH ANNA - UNIT I 3/4 7-18a Amendment No. &52, l l

. ELANT SYSTEMS 3/4.7.3 COMPONENT COOLING WATER SYSIEM 3/4.7.3.1 COMPONENT COOLING WATER SUBSYSTEM - OPERATING LIMITING CONDITION FOR OPERATION 3.7.3.1 Three component cooling water subsystems (shared with Unit 1) shall be OPERABLE ** ** with each subsystem consisting of: l

a. One OPERABLE component cooling water pump and,

b. One OPERABLE component cooling water heat exchanger.

APPLICABILITY: Either Unit in MODES 1,2,3, or 4.

ACIl01

a. With one required component cooling water subsystem inoperable, return the component cooling subsystem to OPERABLE status within the next 7 days, or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

b. With two required component cooling water subsystems inoperable, place both units in HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months , and within the next hour, initiate actions to place both units in COLD SHUTDOWN and continue until COLD SHUTDOWN is achieved.

c. With no component cooling water available to supply the residual heat removal heat exchangers to cool the units, place both units in HOT SHUTDOWN within the next 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and remain in HOT SHUTDOWN until alternate means of decay heat removal can be implemented. Continue actions until both units are in COLD SHUTDOWN.

For the purpose of this Technical Specification, each subsystem is considered OPERABLE if it is operating or ifit can be placed in service from a standby condition by manually unisolating a standby heat exchanger and/or manually starting a standby pump.

" For the purpose of service water system upgrades associated with the supply and return piping to/from the component cooling water heat exchangers (CCHXs), the component cooling water subsystems shall be considered OPERABi E with only one service water loop to/from the CCHXs, provided all other requirements in this specification are met.

This condition is pe.mitted two times only (once for each SW loop) for a duration of up to 49 days each. During each period of operation with only one SW loop available to/from the CCHXs, the provisions of Specification 3.0.4 are not applicable. Upon completion of the work associated with the second 49-day period, this footnote will no longer be applicable.

NORTH ANNA - UNIT 2 3/4 7-14 Amendment No. 440,

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. PLANT SYSTEMS 3/4.7.3 COMPONENT COC G WATER SYSTEM 3/4.7.3.1 COMPONENT COOLING WATER SUBSYSTEM - OPERAllNG SURVEILLANCE REQUIREMENTS 4.7.3.1 Three component cooling water subsystems shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or ,

automatic) servicing in the flow path of the residual heat irmoval system that is not locked, sealed, or otherwise secured in position, is in its correct position. !

b. Each component cooling water pump shall be tested in accordance with Specification 4.0.5.

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NORTH ANNA - UNIT 2 3/4 7-14a Amendment No.

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- PLA'NT SYSTEMS

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3/113 COMPONENT COOLING WATER SYSTEM j l

3/4.7.3.2 COMPONENT COOLING WATER SUBSYSTEM - SHUTDOWN I

LIMITING CONDITION FOR OPERATION i

3.7.3.2 T wo component cooling water subsystems (shared with Unit 1) shall be OPERABLE

with each subsystem consisting of:

a. One OPERABLE component cooling water pump and, !

- b. One OPER.ABLE component cooling water heat exchanger.

APPLICABILITY: Both Units in MODES 5 or 6.

ACTION:

With one required component cooling water subsystem inoperable, immediately suspend all operations involving an increase in the reactor decay heat load or a reduction in boron concentration of the Reactor Coolant System.

SURVEILLANCE REQUIREMENTS 4.7.3.2 At least two component cooling water subsystems shall be demonstrated OPERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or automatic) servicing the flow path of the residual heat removal system that is not locked, sealed, or otherwise secured in position, is in its correct position.

b. Each component cooling water pump shall be tested in accordance with Specification 4.0.5.

For the purposes of this Technical Specification, each subsystem is considered OPERABLE if it is operating or ifit can be placed in service from a standby condition by manually unisolating a standby heat exchanger and/or manually starting a standby pump.

NORTH ANNA - UNIT 2 3/4 714b Amendment No. 440,

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ELA'NT SYSTEMS 3/4.7.4 SERVICE WATER SYSTEM 3/4.7.4.1 EERVICE WATER SYSTEM - OPERATING DMITING CONDITION FOR OPERATION 3.7.4.1 Two service water loops (shared with Unit 1) shall be OPERABLE with each loop consisting of

a. Two OPERABLE service water pumps (excluding auxiliary service water pumps) with their associated normal and emergency power supplies,* and l-

b. An OPERABLE flow path capable of providing cooling for OPERABLE plant components and transferring heat to the service water reservoir.* l APPLICABILITY: Either Unit in MODES 1,2,3 or 4.

ACTION:

a. With one service water pump inoperable, within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months throttle component cooling water heat exchanger flows,in accordance with approved operating procedures, to ensure the remaining service water pumps are capable of providing adequate flow to the recin'ulation spray heat exchangers. The provisions of Specification 3.0.4 are not applicable once component cooling heat exchangers flows are throttled.

b. With two service water pumps inoperable, perform ACTION 3.7.4.1.a within I hour and restore at least one service water pump to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

c. With one service water loop inoperable, except as provided in ACTION 3.7.4.1.a.

restore the inoperable loop to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

For the purpose of service water system upgrades associated with the supply and return piping to/from the component cooling water heat exchangers (CCHXs), one of the two service water (SW) loops is permitted to temporarily bypass the CCHXs, provided all other requirements in this specification are met. This condition is permitted two times only (once for each SW loop) for a duration of up to 49 days each. During each period of operation with only one SW loop available to/from the CCHX.s, four out of four SW pumps (excluding the auxiliary SW pumps) shall remain OPERABLE. With one SW pump inoperable, work may continue provided actions are taken to either restore the pump to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months or restore both SW headers to/from the CCHXs to OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months , or place both units in HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

During each period of operation with only one SW loop available to/from the CCHXs, the automatic closure feature of the SW valves servicing the CCHXs shall be defeated to ensure SW flow to the CCHXs is not interrupted. During each period of operation with only one SW loop available to/from the CCHXs, the provisions of Specification i 3.0.4 are not applicable, provided two SW loops are capable of providing cooling for i the other OPERABLE plant components. Upon completion of the work associated with the second 49-day period, this footnote will no longer be applicable.

NORTH ANNA - UNIT 2 3/4 7-15 Amendment No. 39,56,136,-143,

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PLANT SYSTEMS 3/4.7.4 SERVICE WATER. SYSTEM

'3/4.7.4.1 S.ERVICE WATER SYSTEM - OPERATING LIMITING CONDITION FOR OPERATION

d. The allowable time that one of the two service water loops can be inoperable as specified in ACI' ION 3.7.4.1.c may be extended beyond 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months up to 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months t

as part of service water system upgrades

provided 3 out of 4 service water pumps (the third pump does not require auto start capability) and 2 out c,f 2 auxiliary '

service water pumps have been OPERABLE since initial entry into the action statement and remain OPERABLE during the extended action statement or be in at '

least HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days 0.00833 hours 4.960317e-5 weeks 1.1415e-5 months .

c. With two service water loops inoperable for reasons other than described in ACTION 3.7.4.1.b, place both units in HOT SHUTDOWN within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months and within the following hour, initiate actions to place both units in COLD SHUTDOWN and continue actions until both units are in COLD SHUTDOWN.

SURVEILLANCE REQUIREMENTS 4.7.4.1 At least two service water loops shall be demonstrated O?ERABLE:

a. At least once per 31 days by verifying that each valve (manual, power operated or automatic) servicing safety related equipment that is not locked, sealed, or otherwise secured in position, is in its correct position,

b. At least once per 6 months by measun: ment of the movement of the pumphouse and wing walls.

c. At least once per 18 months during shutdown, by:

1. Verifying that each automatic valve servicing safety related equipment actuates to its correct position on an actual or simulated safety injection signal.

2. Verifying that each automatic service water valve actuates to its correct position on an actual or simulated containment high-high signal.

d. Each service water pump will be tested in accordance with Specification 4.0.5.

Isolation of one service water loop for up to 168 hours0.00194 days 0.0467 hours 2.777778e-4 weeks 6.3924e-5 months is permitted only as part of service water system upgrades. System upgrades include modification and maintenance activities associated with the installation of new discharge headers and spray arrays, mechanical and chemical cleaning of service water piping and valves, pipe repair and replacement, valve repair and replacement, installation of corrosion mitigation measures and inspection of and repairs to buried piping interior coatings and pump or valve house components.

l NORTH ANNA - UNIT 2 3/4 7-15a Amendment No. 436,

no h ,L .,_-. -- u e 3 ATTACHMENT 3 SIGNIFICANT HAZARDS COMGIDERATION VIRGINIA ELECTRIC AND POWER COMPANY

Significant Hazards Consideration Virginia Electric and Power Company is requesting temporary changes to Technical Specifications 3.7.3.1, " Component Cooling Water Subsystem - Operating," and 3.7.4.1, " Service Water System - Operating," for North Anna Power Station Units 1 and 2. These proposed Technical Specifications changes will allow one of the two service water loops to be isolated from the component cooling water heat exchangers during power operation in order to refurbish the isolated service water headers.

North Anna is currently pursuing refurbishment of the 18-inch,20-inch, and 24-inch diameter service water supply and retum lines to/from the Unit 1 and Unit 2 component cooling heat exchangers (CCHXs). Refurbishment of this piping presents a challenge in that it is not possible to isolate and plug or blank the section to be worked in a 7-day time period. The purpose of this submittal is to request temporary changes to the existing service water (SW) and component cooling water (CC) Technical Specifications to permit orderly and efficient conduct of the pipe refurbishment project during two-unit power operation. Specifically, we are proposing to temporarily change TS 3.7.4.1 "Ser/ ice Water System - Operating" to allow operation of the SW system with one independent source of SW to/from the Unit 1 and Unit 2 CCHXs for two periods of up to 49 days each. This proposed change also allows the automatic closure feature of the SW valves to/from the CCHXs to be defeated during the 49-day periods. In addition, we propose to temporarily change TS 3.7.3.1 " Component Cooling Water Subsystem - Operating" with a footnote which considers the CC subsystems OPERABLE with only one independent source of SW provided to/from the CCHXs during these 49-day periods. Further, the proposed change will allow that during operation with only one SW header available to/from the CCHXs, the provisions of Specification 3.0.4 would not be applicable provided two SW loops are capable of providing cooling for the other operable plant components.

Virginia Electric and Power Company has reviewed these proposed changes against the criteria of 10 CFR 50.92 and has concluded that the changes as proposed do not pose a significant hazards consideration. Specifically, operation of North Anna Power Station in accordance with the proposed Technical Specifications changes will not:

1. Involve a significant increase in the probability or consequences of an accident previously evaluated. i The piping refurbishment project and the proposed temporary changes to the SW and CC Technical Specifications have been evaluated to assess their impact on ;

the normal operatlon of the SW and CC systems and to ensure that the design l basis safety functions of each system are preserved. The SW system is required to function during all normal and emergency operating conditions. During normal plant operation, the SW system provides cooling water to the CCHXs, charging l Page 1 of 4

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' pump coolers, instrument air compressor coolers, and control room chiller condensers of both units. During the two 49-day periods, one header will l operated with its 24-inch piping to/from the CCHXs temporarily blanked. To avoid

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operation of the SW pump at abnormal conditions (Iow flow) on this " partially i

deadlocked" header, a temporary cross-connect will be installed to by-pass the CCHXs.

SW system operation with the cross-connect installed was evaluated for design basis accident (DBA) conditions. The DBA condition for the SW system is a loss-of-coolant accident on one unit with simultaneous loss-of-offsite-power to both units. A SW system hydraulic analysis has been performed to verify that adequate flow is provided to the containment recirculation spray heat exchangers (RSHXs) with the temporary cross-connect installed and throttled open, assuming the occurrence of the most limiting single failure. Therefore, there is no increase in probability or consequences of the DBA condition.

Utilizing only one SW header to supply flow to the CCHXs has the potential to '

l affect the reliability of the CC system and all of the equipment cooled by CC. The activities to be performed during the refurbishment project and the various system alignments required have been evaluated using the Individual Plant Examination (IPE) Probabilistic Safety Assessment (PSA) model for North Anna Power Station. This model is used in a manner that is generally consistent with the !

Nuclear Energy Institute (NEI) / Electric Power Research Institute (EPRI) draft PSA Applications Guide (Revision H). The effect on the PSA model is a slight increase in the frequency of reactor trips and an increase in the probability of RHR failure.

The increased frequency of reactor trips is due to the decreased reliability of the CC system to supply cooling to the reactor coolant pump (RCP) motors. When only one SW header is available to the CCHXs, the increased frequency of losing this single header can be conservatively estimated by combining the failure probability of both SW pumps ( approximately 1.5E-4 based on IPE PSA data).

Also considered was the frequency of pipe rupture anywhere in the single available header. When the single SW header fails to supply cooling to the CCHXs, the CC system will heatup causing inadequate cooling for sustained operation of the RCPs. Tripping these pumps results in a reactor trip. The second SW header can be expected to supply other equipment with cooling. A sensitivity analysis shows the increase in CDF as a result of the increased reactor trip frequency to be less than 1E-8 per year.

The CC system is also included in the PSA model as a support system for RHR cooling. The RHR system is used to reduce reactor coolant system temperatures ,

from 350 F (hot shutdown) to 140 F (cold shutdown). The only accident initiator !

that requires the unit to be cooled down and placed on RHR cooling are Page 2 of 4 I

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. sequences which are initiated with a steam generator tube rupture. (Note that, for ;

the North Anna plant design, RHR is separate from the safety injection system and the low head safety injection pumps.) The increased probability for the loss of RHR when only one SW header is available to the CCHXs is estimated.using fault tree analysis and is dominated by the. failure of both SW pumps. The ;

probability for the loss of both SW pumps aligned to the CCHXs is estimated to be l 1.5E-4. The effect of this increase in RHR failure probability was determined by !

adding this probability to the top single event in ~ the RHR function 'and

. recalculating the new CDF. The resulting increase in CDF as's result of RHR !

system failure following a steam generator tube rupture is less than 1E-8 per~.

year.

The CC system is further included in the PSA'model as part of the loss of RCP. i seal cooling as an initiating event and as a loss of function during other initiating event scenarios. The effect on the probability for a loss of RCP seal cooling due to losing CC cooling to the RCP thermal barriers is negligible due to the high reliability of the charging system to provide sealinjection.

The total effect of this pipe refurbishment project was estimated by a sensitivity .

analysis combining both the change in the reactor trip initiating event frequency l and the increased failure probability of RHR resulting in less than a 1E-6 per year increase in CDF. Since this project will not affect the containment systems, there -

would not be any significant change in off-site dose, except that resulting directly _ :

from the increase in CDF. These minor increases in CDF and off-site dose are less than what is defined as risk significant in the NEl / EPRI draft PSA Applications Guide. !

2. Create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed temporary Technical Specifications changes do not affect the basic ;

method of operation of the SW or CC systems. The purpose of the proposed l changes is to permit extended operation of the CC system with one independent source of SW cooling. During the project, there will be a significant time period i

when all the CCHXs are aligned to one SW loop, the possibility of an interruption of SW supply to the heat exchangers during a DBA is eliminated by defeating the ,

closure of the 24-inch SW isolation MOVs to the CCHXs on a Sl/CDA signal.

Both SW headers will be available for equipment required for safe shutdown of the units (i.e., RSHXs, charging pumps, and CR/ESGR chillers). The SW pipe repair activities and the installation / removal of the SW cross-connect piping do not create the possibility for a malfunction of equipment different than previously evaluated. Therefore, implementation of the restoration project and approval of

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' the proposed Technical' Specifications changes will not introduce any new- :

accident initiators nor affect the performance of accident mitigation systems.

3. Involve a significant reduction in a margin of safety.

.The proposed changes to the schedule only_ provide operational flexibility to f perform the required SW pipe refurbishment. The Technical Specifications l continue to require the SW and CC systems to remain functional during the I period with a single SW supply to the CCHXs. As stated in item (1) above, the SW system is fully capable of performing its DBA function during the course of the ;

pipe refurbishment project with the proposed Technical Specification changes in :

place. The effect of this pipe refurbishment project on;CC system reliability was 1 estimated by a sensitivity analysis combining both the change in the reactor trip initiating event frequency and the increased failure probability of RHR resulting in !

less than a 1E-6 per year increase in CDF. Since this project will not affect the containment systems, there would not be any significant change in off-site dose, except that resulting directly from the' increase in CDF. These minor increases in CDF and off site dose are less than what is defined as risk significant in the NEl / ,

EPRI draft PSA Applications Guide.+ Therefore, there is not a significant reduction ;

i in margin of safety.

Virginia Electric and Power Company concludes that the.actrvities associated with -

these proposed Technical Specification changes satisfy ine no significant hazards '

consideration of the criteria of 10 CFR 50.92 and, accordingly, a no significant hazards consideration finding is justified.

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ML20087G347

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