ML20094D019

Proposed Tech Specs Re Allowed Outage Time for PORV Nitrogen Accumulators & Separate Actions for PORV Inoperability

ML20094D019
Person / Time
Site:	North Anna
Issue date:	10/25/1995
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML20094D017	List: ML20094D013 ML20094D019
References
NUDOCS 9511030085
Download: ML20094D019 (19)

Text

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l Attachment 2 Technical Specifications Changes l

9511030085 951025 PDR ADOCK 05000338 P PDR

REACTOR COOLANT SYSTEM SAFETY AND REllEF VALVES - OPERATING

. RELIEF VALVES LIMITING CONDITION FOR OPERATION 3.4.3.2 Both power operated relief valves (PORVs) and their associated block valves shall be OPERABLE.

APPLICABILITY: MODES 1,2, and 3.

ACTION:

A. PORV(s):

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1. With one or both POP.V(s) inoperable solely because of excessive seat leakage, l within I hour either . : store the PORV(s) to OPERABLE status or close the '

associated block valve (s) with power maintained to the block valve (s); otherwise, 1 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

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2. With one or both PORV(s) inoperable because of (an) inoperable backup nitrogen supply (ies), within 14 days either restore the PORV(s) backup nitrogen supply (ies) to OPERABLE status or be in 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

3. With one or both PORV(s) inoperable due to a malfunction in the PORV automatic control system, within I hour restore the affected automatic control system (s) to OPERABLE status or place and maintain the affected PORV(s) in manual control.

4. With one PORV inoperable due to causes other than those addressed in ACTIONS A.1, A.2 or A.3 above, within I hour either restore the PORV to OPERABLE status or close its associated block valve and remove power from the block valve; restore the PORV to OPERABLE status within the following 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in 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 l 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

5. With both PORVs inoperable such that ACTIONS A.1, A.2 or A.3 above do not apply, within I hour either restore at least one PORV to OPERABLE status or close the associated block valves and remove power from the block valves and be in 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

6. The provisions of Specification 3.0.4 are not applicable.

NORTH ANNA - UNIT 1 3/4 4-7a Amendment No. 32,189,

_._ ______ _., .__.. _l l .

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REACTOR COOLANT SYSTEM S AFETY AND RELIEF VALVES - OPERATING RELIEF VALVES LIMITING CONDITION FOR OPERATION ACTION: (Continued)

B. Block Valves

1. With one block valve inoperable, within I hour either restore the block valve to j OPERABLE status or place its associated PORV in manual control; restore the block valve to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 l 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

2. With both block valves inoperable, within I hour either restore the block valves to OPERABLE status or place the PORVs in manual control; restore at least one block valve to OPERABLE status within the next hour; restore the remaining inoperable block valve to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY l

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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

3. The provisions of Specification 3.0.4 are not applicable.

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SURVEILLANCE REQUIREMENTS 4.4.3.2.1 In addition to the requirements of Specification 4.0.5, each PORV shall be demonstrated OPERABLE: I

a. At least once per 31 days by performing a CHANNEL FUNCTIONAL TEST, excluding valve operation, and ,

b. At least once per 18 months by:

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1. Operating the PORV through one complete cycle of full travel during l MODES 3 or 4, and

2. Operating the solenoid air control valves and check valves on the~ associated

, accumulators in the PORV control systems through one complete cyc.le of full travel, and l

3. Performing a CHANNEL CALIBRATION of the actuation l instrumentation. I

c. At least once per 7 days by verifying that the pressure in the PORV nitrogen accumulators is greater than the surveillance limit.

4.4.3.2.2 Each block valve shall be demonstrated OPERABLE at least once per 92 days by operating the valve through one complete cycle of full travel unless the block valve is closed in order to meet the requirements of ACTION A 4 or A.5 in Specification 3.4.3.2. l NORTH ANNA - UNIT 1 3/4 4-7b Amendment No. 489,

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g - ,y_ . _

y e-.* -. - y.- - u-,r. y-e. g -. ee- -W' - - *>+--- r

1

. REACTOR COOLANT SYSTEM 3

LOW-TEMPERATURE OVERPRESSURE PROTECTION i SURVEILLANCE REQUIREMENTS i

, 4.4.9.3 Each PORV shall be demonstrated OPERABLE by:

l a. Performance of a CHANNEL FUNCTIONAL TEST on the PORV actuation channel, but excluding valve operation, within 31 days prior to entering a condition in which the PORV is required OPERABLE and at least once per 31 days thereafter when the PORV is required OPERABLE.

b. Performance of a CHANNEL CALIBRATION on the PORV actuation channel, at

least once per 18 months.

c. Verifying the PORV keyswitch is in the Auto position and the PORV isolation valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> when the PORV is being used for overpressure protection.

d. At least once per 7 days by verifying that the pressure in the PORV nitrogen accumulators is greater than the surveillance limit,

e. Testing pursuant to Specification 4.0.5.

NORTH ANNA - UNIT 1 3/4 4-3~2 Amendment No. 16,31,189,

3/L4 RE ACTOR COOLANT SYSTEM BASES within 20 F of the operating loops. Making the reactor suberitical prior to loop startup prevents any power spike which could result from this cool water induced reactivity transient.

3/4.4.2 AND 3/4.4.3 SAFETY AND RELIEF VALVES The pressurizer code safety valves operate to prevent the RCS from being pressurized above its Safety Limit of 2735 psig. Each safety valve is designed to relieve 380,000 lbs per hour i of saturated steam at the valve set point. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur during hot shutdown, in the event that no safety valves are OPERABLE, an operating RHR loop, connected to the RCS, or the power operated relief valves (PORVs) will provide overpressure relief capability and will prevent RCS overpressurization.

During operation, all pressurizer code safety valves must be OPERABLE to prevent the RCS from being pressurized above its safety limit of 2735 psig.The combined relief capacity of all of these valves is greater than the maximum surge rate resulting from a complete loss of load assuming no reactor trip until the first Reactor Protective System trip setpoint is reached (i.e., no credit is taken for a direct reactor trip on the loss of load) and also assuming no operation of the power operated relief valves or steam dump valves.

Demonstration of the safety valves' lift settings will occur only during shutdown and will be performed in accordance with the provisions of Section XI of the ASME Boiler and Pressure Vessel Code.

The power operated relief valves (PORVs) and pressurizer steam bubble function to relieve reactor coolant system (RCS) pressure during all design transients up to and including the design step load decrease with concurrent operation of the condenser with steam dumps. Operation of the PORVs minimizes the undesirable opening of the spring loaded pressurizer code safety valves.

Each PORV has a remotely operated block valve supplied from emergency power to provide isolation capability should a relief valve become inoperable due to:

1. seat leakage, or

2. a mechanical or control system problem which results in either the valve sticking open or the potential for a spurious opening of the valve.

The OPERABILITY of the PORVs and block valves is determined on the basis of their being capable of performing the following functions:

a) Manual control of the reactor coolant system pressure. This function is assumed for mitigation of the steam generator tube rupture accident and is therefore considered a safety function.

NORTH ANNA - UNIT 1 B 3/4 4'-2 Amendment No. 32, ! A 1,189,

l 3/fL4 REACTOR COOLANT SYSTEM i

BASES b) Maintaining the integrity of the reactor coolant pressure boundary. l

c) Manual control of the block valve to (1) unblock an isolated PORV to allow it to bc

used for manual control of reactor coolant system pressure (Item a, above), and (2) isolate a PORV with excessive seat leakage (Item b,~ above).

d) Automatic control of PORVs to control RCS pressure. This is a function that reduces l

challenges to the code safety valves for overpressurization events, e) Manual control of a block valve to isolate a stuck PORV or a PORV which has the potential for spurious opening due to a control system malfunction.

If a PORV is inoperable because of excessive seat leakage, closure of the block valve is i l

required to restore RCS pressure boundary integrity. Power is maintained to the block valves so that the PORVs will continue to be available for the safety related function of manual RCS depressurization in the event of a steam generator tube rupture. In addition, the automatic pressure l control capability could be restored by opening the block valves. Therefore, continued operation is allowed.

f With one or both PORVs inoperable due to an inoperable backup nitrogen supply, continued operation for 14 days is allowed provided the normal motive force for the PORVs,i.e.,

the instrument air system, continues to be available. Instrument air has a high system reliability, and the likelihood ofits being unavailable during a demand for PORV operation is low enough to justify a reasonable length of time (i.e.,14 days) to repair the nitrogen system.

If one or both PORVs are inoperable due to a malfunction in the PORV automatic control system, the PORV should be placed in manual control to limit the potential for a spurious opening  ;

of the PORV. Closure of the block valves is not required in this case so that the manual function remains readily available.

If one or both block valves are inoperable, the associated PORV(s) are placed in manual control to limit the potential for a spurious PORV opening due to a control system malfunction which would not be isolable via the block valve. The time allowed to restore the block valve (s) to

OPERABLE status is based on the remedial action time limits for inoperable PORV control systems since the PORVs are not capable of mitigating an overpressure event when placed in manual control.

Surveillance Requirements provide assurance that the PORVs and block valves can perform their functions. Specification 4.4.3.2.1 addresses the PORVs, including the backup nitrogen supply system, and Specification 4.4.3.2.2 addresses the block valves. The block valves are exempt from the surveillance requirements to cycle the valves when they have been closed to comply with the ACTION requirements. This precludes the need to cycle the valves with full NORTH ANNA - UNIT I B 3/4 4-2a Amendment No. 49,

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3L4A REACTOR COOLANT SYSTEM ,

BASES l

system differential pressure or when maintenance is being performed to restore an inoperable PORV to OPERABLE status, Surveillance limits are established for the pressure in the backup nitrogen accumulators to  ;

ensure there is adequate motive power for the PORVs to cope with a steam generator tube rupture I coincident with loss of the containment instrument air system.

Surveillance Requirement 4.4.3.2.1.b provides for the testing of the mechanical and I electrical aspects of the PORVs and their associated control systems. This testing is performed in MODE 3 or 4 to limit the potential of spurious or inadvertent opening of a PORV during power operation while maintaining a temperature and pressure environment which is representative of j power operating conditions.

3/4.4.4 PRESSURIZER The limit on the maximum water volume in the pressurizer assures that the parameter is j maintained within the normal steady state envelope of operation assumed in the S AR. The limit is consistent with the initial SAR assumptions. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> periodic surveillance is sufficient to ensure that the parameter is restored to within its limit following expected transient operation. The maximum water volume also ensures that a steam bubble is formed and thus the RCS is not a hydraulically solid system.

^

NORTH ANNA - UNIT I B 3/4 4-2b Amendment No.

1 REACTOR COOLANT SYSTEM I BASES Low-Temoerature Overoressure Protection

! The OPERABILITY of two PORVs or an RCS vent opening of greater than 2.07 square

inches ensures that the RCS will be protected from pressure transients which could exceed the

limits of Appendix G to 10 CFR Part 50 when one or more of the RCS cold legs are less than or i

equal to 235'F. Either PORV has adequate relieving capability to protect the RCS from

overpressurization when the transient is limited to either (1) the start of an idle RCP with the secondary water temperature of the steam generator less than or equal to S0*F above the RCS cold 1 leg temperatures or (2) the start of a charging pump and its injection into a water-solid RCS.

1 Automatic or passive low temperature overpressure protection (LTOP) is required whenever any RCS cold leg temperature is less than 235 F. This temperature is the water temperature corresponding to a metal temperature of at least the limiting RTNDT + 50 F +

instrument uncertainty. Above 235 F administrative control is adequate protection to ensure the limits of the heatup curve (Figure 3.4-2) and the cooldown curve (Figure 3.4-3) are not violated.

The concept of requiring automatic LTOP at the lower end, and administrative control at the upper end, of the Appendix G curves is further discussed in NRC Generic Letter 88-11.

Surveillance limits are established for the pressure in the backup nitrogen accumulators to ensure there is adequate motive power for the PORVs to cope with an inadvertent start of a high head safety injection pump in a water solid condition, allowing adequate time for the operators to respond to terminate the event.

1 1

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J NORTH ANNA - UNIT I B 3/4 4'8

- Amendment No. 71, ! !?,170, 489,

l REACTOR COOL ANT SYSTEM S AFETY AND RELIEF VALVES - OPERATING RELIEF VALVES LIMITING CONDITION FOR OPERATION 3.4.3.2 Both power operated relief valves (PORVs) and their associated block valves shall be OPERABLE.

APPLICABILITY: MODES 1,2, and 3.

ACTION:

A. PORV(s):

1, With one or both PORV(s) inoperable sole'ly because of excessive seat leakage,

within I hour either restore the PORV(s) to OPERABLE status or close the associated block valve (s) with power maintained to the block valve (s); otherwise, 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

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2. With one or both PORV(s) inoperable because of(an) inoperable backup nitrogen l supply (ies), within 14 days either restore the PORV(s) backup nitrogen supply (ies) l to OPERABLE status or be in 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 l SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

3. With one or both PORV(s) inoperable due to a malfunction in the PORV automatic control system, within I hour restore the affected automatic control system (s) to l OPERABLE status or place and maintain the affected PORV(s) in manual control. '

4. With one PORV inoperable due to causes other than those addressed in ACTIONS A.1, A.2 or A.3 above, within I hour either restore the PORV to OPERABLE status or close its associated block valve and remove power from the block valve; restore the PORV to OPER ARLE status within the following 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

5. With both PORVs inoperable such that ACTIONS A.1, A.2 or A.3 above do not apply, within I hour either restore at least one PORV to OPERABLE status or close the associated block valves and remove power from the block valves and be in 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

6. The provisions of Specification 3.0.4 are not applicable.

NORTH ANNA - UNIT 2 3/4 4 ~/a Amendment No. 4-70,

4 RE ACTOR COOLANT SYSTEM a

S AFETY AND RELIEF VALVES - OPERATING RELIEF VALVES LIMITING CONDITION FOR OPERATION ACTION: (Continued)

B. Block Valves:

1. With one block valve inoperable, within I hour either restore the block valve to OPERABLE status or place its associated PORV in manual control; restore the l block valve to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

2. With both block valves inoperable, within I hour either restore the block valves to OPERABLE status or place the PORVs in manual control; restore at least one block valve to OPERABLE status within the next hour; restore the remaining inoperable block valve to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or 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 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. l

3. The provisions of Specification 3.0.4 are not applicable.

SURVEILLANCE REQUIREMENTS 4.4.3.2.1 In addition to the requirements of Specification 4.0.5, each PORV shall be demonstrated OPERABLE:

a. At least once per 31 days by performing a CHANNEL FUNCTIONAL TEST, excluding valve operation, and

b. At least once per 18 months by:

l 1 Operating the PORV through one complete cycle of full travel during MODES 3 or 4, and

2. Operating the solenoid air control valves and check valves on the associated accumulators in the PORV control systems through one complete cycle of full travel, and l

3. Performing a CHANNEL CALIBRATION of the actuation instrumentation.

c. At least once per 7 days by verifying that the pressure in the PORV nitrogen accumulators is greater than the surveillance limit.

4.4.3.2.2 Each block valve shall be demonstrated OPERABLE at least once per 92 days by operating the valve through one complete cycle of full travel unless the block valve is closed in order to meet the requirements of ACTION A 4 or A.5 in Specification 3.4.3.2. l NORTH ANNA - UNIT 2 3/4 4 7b Amendment No. MO,

REACTOR COOLANT SYSTEM LOW-TEMPERATURE OVERPRESSURE PROTECTION SURVEILLANCE REQUIREMENTS 4.4.9.3 Each PORV shall be demonstrated OPERABLE by:

a. Performance of a CHANNEL FUNCTIONAL TEST on the PORV actuation channel, but excluding valve operation, within 31 days prior to entering a condition in which the PORV is required OPERABLE and at least once per 31 days thereafter when the PORV is required OPERABLE.

b. Performance of a CHANNEL CALIBRATION on the PORV actuation channel, at least once per 18 months.

c. Verifying the PORV keyswitch is in the AUTO position and the PORV isolation valve is open at least once per 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> when the PORV is being used for overpressure protection,

d. At least once per 7 days by verifying that the pressure in the PORV nitrogen accumulators is greater than the surveillance limit,

e. Testing pursuant to Specification 4.0.5.

NORTil ANNA - UNIT 2 3/4 4-31 Amendment No. 4M,

4

- REACTOR COOLANT SYSTEM BASES 3/4.4.2 AND 3/4.4.3 SAFETY AND RELIEF VALVES The pressurizer code safety valves operate to prevent the RCS from being pressurized l,

above its Safety Limit of 2735 psig. Each safety valve is designed to relieve 380,000 lbs per hour of saturated steam at the valve set point. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur during hot shutdown. In the event that no safety valves are OPERABLE, an operating RHR loop, connected to the RCS, or the power operated relief valves (PORVs) will provide overpressure relief capability and will prevent RCS overpressurization.

During operation, all pressurizer code safety valves must be OPERABLE to prevent the RCS from being pressurized above its safety limit of 2735 psig. The combined relief capacity of all of these valves is greater than the maximum surge rate resulting from a complete loss of load

assuming no reactor trip until the first Reactor Protective System trip setpoint is reached (i.e., no credit is taken for a direct reactor trip on the loss of load) and also assuming no operation of the i power operated relief valves or steam dump valves. l Demonstration of the safety valves' lift settings will occur only during shutdown and will 4

be performed in accordance with the provisions of Section XI of the ASME Boiler and Pressure Vessel Code.

! The power operated relief valves (PORVs) and pressurizer steam bubble function to relieve reactor coolant system (RCS) pressure during all design transients up to and including the design step load decrease with concurrent operation of the condenser with steam dumps. Operation of the PORVs minimizes the undesirable opening of the spring loaded pressurizer code safety valves.

Each PORV has a remotely operated block valve supplied from emergency power to provide isolation capability should a relief valve become inoperable due to:

i

1. seat leakage, or

2. a mechanical or control system problem which results in either the valve sticking open or the potential for a spurious opening of the valve.

The OPERABILITY of the PORVs and block valves is determined on the basis of their being capable of perfomiing the following functions:

a) Manual control of the reactor coolant system pressure. This function is assumed for mitigation of the steam generator tube rupture accident and is therefore considered a safety function.

i b) Maintaining the integrity of the reactor coolant pressure boundary.

NORTH ANNA - UNIT 2 B 3/4 4:2 Amendment No.121, !?0,

l 1 1

314A REdCTOR COOLANT SYSTEM ' ,

l 1

BASES l

c) Manual control of the block valve to (1) unblock an isolated PORV to allow it to be' used for manual control of reactor coolant system pressure (Item a. above), and (2)  !

isolate a PORV with excessive seat leakage (Item b, above).  ;

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l d) Automatic control of PORVs to control RCS pressure. This is a function that reduces j challenges to the code safety valves for overpressurization events.

l e) : Manual control of a block valve to isolate a stuck PORV or a PORV which has the

_ potential for spurious opening due to a control system malfunction.  !

If a PORV is inoperable because of excessive seat leakage, closure of the block valve is l required to restore RCS pressure boundary integrity. Power is maintained to the block valves so j that the PORVs will continue to be available for the safety related function of mam si RCS

[ depressurization in the event of a steam generator tube rupture. In addition, the automatic pressure l

control capability could be restored byopening the block valves. Therefore, continued operation is allowed.

e With one or both PORVs inoperable due to an inoperable backup nitrogen supply,

! continued operation for 14 days is allowed provided the normal motive force for the PORVs, i.e.,

l the instrument air system, continues to be available. Instrument air has a high system reliability, l and the likelihood ofits being unavailable during a demand for PORV operation is low enough to justify a reasonable length of time (i.e.,14 days) to repair the nitrogen system.

If one or both PORVs are inoperable due to a malfunction in the PORV automatic control system, the PORV should be placed in manual control to limit the potential for a spurious opening of the PORV. Closure of the block valves is not required in this case so that the manual function remains reactily available.

If one or both block valves are inoperable, the associated PORV(s) are placed in manual

~

! control to limit the potential for a spurious PORV opening due to a control system malfunction l which would not be isolable via the block valve. The time allowed to restore the block valve (s) to l OPERABLE status is based on the remedial action time limits for inoperable PORV control '

systems since the PORVs are not capable of mitigating an overpressure event when placed in manual control.

l Surveillance Requirements provide assurance that the PORVs and block valves can perform their functions. Specification 4.43.2.1 addresses the PORVs, including the backup nitrogen supply system, and Specification 4.4.3.2.2 addresses the block valves. The block valves are exempt from the surveillance requirements to cycle the valves when they have been closed to i

comply with the ACTION requirements. This precludes the need to cycle the valves with ru !

, system differential pressure or when maintenance is being performed to restore an inoperable PORV to OPERABLE status.

NORTH ANNA - UNIT 2 B 3/4 4:2a Amendment No. 4-70,

1 3/4.4 REACTOR COOLANT SYSTEM BASES Surveillance limits are established for the pressure in the backup nitrogen accumulators to ensure there is adequate motive power for the PORVs to cope with a steam generator tube rupture coincident with loss of the containment instrument air system.

Surveillance Requirement 4.4.3.2.1.b provides for the testing of the mechanical and electrical aspects of the PORVs and their associated control systems. This testing is performed in MODE 3 or 4 to limit the potential of spurious or inadvertent opening of a PORV during power operation while maintaining a temperature and pressure environment which is representative of power operating conditions.

3/4.4.4 PRESSURIZER The limit on the maximum water volume in the pressurizer assures that the parameter is maintained within the normal steady state envelope of operation assumed in the S AR. The limit is consistent with the initial S AR assumptions. The 12-hour periodic surveillance is sufficient to ensure that the parameter is restored to within its limit following expected transient operation. The maximum water volume also ansures that a steam bubble is formed and thus the RCS is not a hydraulically solid system. The requirement that a minimum number of pressurizer heaters be OPERABLE ensures that the plant will be able to establish natural circulation.

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NORTH ANNA - UNIT 2 B 3/4 4-2b Amendment No.

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1 REACTOR COOLANT SYSTEM BASES I

Low-Temperature Overoressure Protection The OPERABILITY of two PORVs or an RCS vent opening of greater than 2.07 square l' inches ensures that the RCS will be protected from pressure transients which could exceed the limits of Appendix G to 10 CFR Part 50 when one or more of the RCS cold legs are less than or equal to 270 F. Either PORV has adequate relieving capability to protect the RCS from overpressurization when the transient is limited to either (1) the start of an idle RCP with the l

secondary water temperature of the steam generator less than or equal to 50 F above the RCS cold leg temperatures or (2) the start of a charging pump and its injection into a water-solid RCS.

Automatic or passive low temperature overpressure protection (LTOP) is required whenever any RCS cold leg temperature is less than 270 F. This temperature is the water l temperature corresponding to a metal temperature of at least the limiting RTNDT + 50 F +

instrument uncertainty. Above 270 F administrative control is adequate protection to ensure the limits of the heatup curve (Figure 3.4-2) and the cooldown curve (Figure 3.4-3) are not violated.

The concept of requiring automatic LTOP at the lower end, and administrative control at the upper end, of the Appendix G curves is further discussed in NRC Generic Letter 88-11.

I Surveillance limits are established for the pressure in the backup nitrogen accumulators to ensure there is adequate motive power for the PORVs to cope with an inadvertent start of a high head safety injection pump in a water solid condition, allowing adequate time for the operators to respond to terminate the event.

3/4.4.10 SIRUCTURAL INTEGRITY 3/4.4.10.1 ASME CODE CLASS 1. 2 and 3 COMPONENTS The inspection programs for ASME Code Class 1,2 and 3 Reactor Coolant System components ensure that the structural integrity of these components will be maintained at an acceptable level throughout the life of the plant. To the extent applicable, the inspection program for components is in compliance with Section XI of the ASME Boiler and Pressure Vessel Code.

NORTH ANNA - UNIT 2 B 3/4 4'-8 Auendment No. 119,170,

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l Attachment 3 Significant Hazards Consideration

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SIGNIFICANT HAZARDS CONSIDERATION

-Virginia Electric and Power Company is proposing changes to the Technical Specifications for North Anna Power Station Units 1 and 2. The Technical Specification sections being changed govern the operability of the pressurizer PORVs.

For operation at power (Modes 1-3), the proposed changes

- provide separate ACTION statements for PORVs which are inoperable by virtue of seat leakage, an inoperable backup nitrogen supply, an inoperable automatic control system and other causes (e.g. mechanical  :

1 valve failure). This allows more specific and appropriate actions for each  !

I case.

- provide for a 14 day allowed outage time for inoperable backup nitrogen supplies. l 1

- add a surveillance requirement on backup nitrogen supply accumulator pressure. ,

For operation in Modes 4-6 when the Low Temperature Overpressure Protection System (LTOPS) is required, a surveillance reg;irement to monitor the backup nitrogen accumulator pressure has been added.

Virginia Electric and Power Company has reviewed the 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

A previously evaluated.

The PORVs are assumed to mitigate the consequences of a steam generator )

tube rupture as describec in the North Anna UFSAR as well as to limit the undesired opening of the pressurizer safety valves fvr a primary overpressure event. The proposed action statements ensure that the steam generator tube rupture accident analysis requirements are met. The proposed Technical Specification changes require the backup nitrogen supply be available for the PORVs to be considered operable and add action statements and surveillance requirements for the nitrogen supply commensurate with its significance. The l proposed action statements enhance the availability of the automatic actuation l c' the PORVs by not requiring the block valves to be closed when the backup l nitrogen supplies are inoperable. The proposed surveillance requirements enhance the reliability of the backup nitrogen supply to the PORVs by verifying that there is sufficient nitrogen pressure in the accumulators for the PORVs to l perform their design function. The proposed Technical Specification changes l do not change any accident analyses, therefore, the probability of any accident and its resulting consequences are not increased.

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

previously evaluated.

The proposed Technical Specification changes do not involve any physical modification to the plant or result in a change in a method of operation. The backup nitrogen supply continues to be required for PORV operability. The proposed Technical Specification changes provide operational flexibility and ensure the availability of the PORVs using the normal supply of instrument air while the backup nitrogen supply is being restored. This also prevents undesirable challenges to the pressurizer safety valves. The new surveillance requirements verify that there is sufficient nitrogen pressure in the accumulators for the PORVs to perform their design functions.

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

The proposed Technical Specification changes do not affect any safety limits or limiting safety. system settings. The availability of the PORVs will be maintained as required in Generic Letter 90-06. The proposed Technical Specifications will continue to ensure that the PORVs will be capable of performing their intended functions.

Virginia Electric and Power Company concludes that the activities associated with these proposed Technical Specification changes satisfy the no significant hazards consideration of the criteria of 10 CFR 50.92 and, accordingly, a no significant hazards consideratien finding is justified.

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