Text

Proposed Tech Specs Re PORVs & Block Valves
	ML20086C031
Person / Time
Site:	Summer
Issue date:	06/30/1995
From:	; SOUTH CAROLINA ELECTRIC & GAS CO.
To:	;
Shared Package
ML20086C027	List: ML20086C031; RC-95-0167, Application for Amend to License NPF-12,consisting of TS Change TSP 950002,revising TS 3/4.4.4 for Pressurizer PORVs to Follow Guidance of GL 90-06,GI 70 & Improved Westinghouse Standardized TS;
References
	NUDOCS 9507060243
	Download: ML20086C031 (16)
	v • d • e

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. l REACTOR COOLANT SYSTEM 3/4.4.4 RELIEF VALVES LIMITING C0leITION FOR OPERATION l

3.4.4 All power operated relief valves (PORVs) and their essociated block valves shall be OPERABLE.

APPt.ICA8ILITY: MODES 1, 2, and 3.

ACTION:

Witt. . m .i i. FK.s )

e,- . le , .it;. .i. I t.e ei ti.. . . 6. . -

i RV(s) to OPERABLE status or close the associated bloc !

valve (s remove power free the block valve (s); o se, be in Rept.Ac.ar at least HOT within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months COLD SHUTDOWN :

with within the following 3 .

35 EAT l l

b. With one or more block v s inoper within 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months either !

, restore the blo e(s) to OPERABLE status se the block valve (s emove power from the block valve (s); et , be in st HOT STANDBY within the next 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in COLD SHU mith" th: fel b ir.; 20 r.: r:.

h p' Tne provisions of Specification 3.0.4 are not applicable.

I SURVEILLANCE REQUIREMENTS i 2.4.4.1 In accition to the recuirements of Soecification 4.0.5. eacn PORV snali ce comonstrateo OPERAELE at least once per 18 montns eyX l

c. . " rf; m r.;; ;f : C""9:L O'.LI"""T!^^' :.r.c -

l

-tr- Operating the valve through one complete cycle of full trave 1x4 URIN (P NODES

Joe 4 j 4.4.4.2 Each block valve shall be demonstrated OPERABLE at least once per 92 cays by operating the valve through one complete cycle of full travel unless the blocx valve is closed with the power removed in oroer to meet the i ecut rements of 3.4. 4.p 3. 4. 4.)(g or J.4.4. d.

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Document ContrelDesk SCE&G-VCSNS TSP 950002 RC-95-0167 Insert 1 Page 1 of3 INSERT 1

a. With one or more PORV(s) inoperable and capable of being manually cycled, within I hour:

1) restore the PORV(s) to OPERABLE status or

2) close the associated block valve (s) and maintain power to the block valve; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

b. With one PORV inoperable and not capable of being manually cycled, within 1 hour:

1) restore the PORV to OPERABLE status or to a condition where it may be manually cycled

or

2) close its associated block valve and remove power from the block valve; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

c. With two PORVs inoperable and not capable ofbeing manually cycled,

1) within 1 hour:

a) restore the PORVs to OPERABLE status or to a condition where they are capable of being manually cycled

or b) close the associated block valves and remove power from the block valves and

2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore a minimum of two PORVs to OPERABLE status or b) restore a minimum of two PORVs to a condition where they are capable of being manually cycled *;

otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

If a PORV is inoperable but capable of being manually cycled, the associated block valve must be closed with power maintained to the block valve.

Document Control Desk SCE&G- VCSNS TSP 950002 RC-95-0167 Insert 1 Page 2 of 3

d. With three PORVs inoperable and not capable of being manually cycled,

1) within 1 hour:

a) restore at least one PORV to OPERABLE status or to a condition where it is capable of being manually cycled *, or b) close and remove power from the block valves for any PORVs remaining inoperable and not capable of being manually cycled and

2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s: >

a) restore a minimum of two PORVs to OPERABLE status or i b) restore a minimum of two PORVs to a condition where they ,

can be manually cycled *; ;

otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

e. With one blockvalveinoperable:

1) within 1 hour:

a) restore the block valve to OPERABLE status, or I b) place the associated PORV in manual control and

2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore the block valve to OPERABLE status or b) close the block valve and remove power from the block valve; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

f. With twoblock valvesinoperable:

1) within 1 hour:

a) restore the block valves to OPERABLE status, or b) place the associated PORVs in manual control and

2) within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore at least two of the three block valves to OPERABLE status and b) ensure that the remaining inoperable block valve is closed and the poweris removed; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

If a PORV is inoperable but capable of being manually cycled, the associated block valve must be closed with power maintained to the block valve.

a l.

l

e Document Control Desk SCE&G-VCSNS TSP 950002 RC-95-0167 Insert 1 Page 3 of3

g. With three block valvesinoperable:

1) within 1 hour:

a) restore the block valves to OPERABLE status, or b) place the associated PORVs in manual control and

2) within the next 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months restore at least one of the three block valves to OPERABLE status and

3) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore at least two of the three block valves to OPERABLE status and b) ensure that the remaining inoperable block valve is closed and the poweris removed; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

+

' REACTOR COOLANT SYSTEM 3/4.4.4 RELIEF VALVES l LIMITING CONDITION FOR OPERATION 3.4.4 All power operated relief valves (PORVs) and their associated block valves shallbe OPERABLE. !

1 ,

j APPLICABILITY: MODES 1,2, and 3.

! ACTION: t

a. With one or more PORV(s) inoperable and capable of being manually

[ cycled, within 1 hour:

l r 1) restore the PORV(s) to OPERABLE status or, !

, 2) close the associated block valve (s) and maintain power to the l i block valve; i

otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . l t

b. With one PORV inoperable and not capable of being manually cycled, ;

! within 1 hour: i l 1) restore the PORV to OPERABLE status or to a condition where i l-it may be manually cycled

or t

2) close its associated block valve and remove power from the !

block valve;

L otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . ;

< c. With two PORVs inoperable and not capable of being manually cycled, l

, 1) within I hour:

. a) restore the PORVs to OPERABLE status or to a condition i where they are capable of being manually cycled

or j

[ b) close the associated block valves and remove power from the block valves and i

! 2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s: ;

l a) restore a minimum of two PORVs to OPERABLE status or ;

i b) restore a minimum of two PORVs to a condition where they !

are capable of being manually cycled *;

- otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

Y h

~

i

If a PORV is inoperable but capable of being manually cycled, the associated block valve must be closed with power maintained to the block valve. I i

SUMMER-UNIT 1 3/4 4-10 Amendment No.

1

l l

' REACTOR COOLANT SYSTEM LIMITING CONDITION FOR OPERATION ACTION: (Continued)

d. With three PORVs inoperable and not capable of being manually cycled, 4

1) within 1 hour: l a) restore at least one PORV to OPERABLE status or to a !

condition where it is capable of being manually cycled *, or b) close and remove power from the block valves for any PORVs remaining inoperable and not capable of being manually cycled and

2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore a minimum of two PORVs to OPERABLE status or b) restore a minimum of two PORVs to a condition where they ,

can be manually cycled *; L otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

l

e. With one block valve inoperable:

1) within I hour:

a) restore the block valve to OPERABLE status, or b) place the associated PORV in manual control and

2) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s: ;

a) restore the block valve to OPERABLE status or b) close the block valve and remove power from the block valve; otherwise, 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 i in HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . ;

f. With twoblock valvesinoperable:

1) within 1 hour:

a) restore the block valves to OPERABLE status, or :

b) place the associated PORVs in manual control and

2) within 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s:

a) restore at least two of the three block valves to OPERABLE !

status and ,

b) ensure that the remaining inoperable block valve is closed l and the poweris removed; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months .

l If a PORV is inoperable but capable of being manually cycled, the associated block valve must be closed with power maintained to the block valve.

SUMMER-UNIT 1 3/4 4-10a Amendment No.

_. __ - - . .- _ _ - ~

I :

' REACTOR COOLANT SYSTEM l LIMITING CONDITION FOR OPERATION ACTION: (Continued)

g. With three block valvesinoperable:

1) within I hour:

a) restore the block valves to OPERABLE status, or b) place the associated PORVs in manual control and

2) within the next 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months restore at least one of the three block valves to OPERABLE status and

3) within the next 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months s: .

a) restore at least two of the three block valves to OPERABLE status and b) ensure that the remaining inoperable block valve is closed and the power is removed; otherwise, 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 HOT SHUTDOWN within the following 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months ,

h. The provisions of Specification 3.0.4 are not applicable. l SURVEILLANCE REQUIREMENTS ;

4.4.4.1 In addition to the requirements of Specification 4.0.5, each PORV i shall be demonstrated OPERABLE at least once per 18 months by. operating :

the valve through one complete cycle of full travel during MODES 3 or 4. !

4.4.4.2 Each block valve shall be demonstrated OPERABLE at least once per 92 days by o grating the valve through one complete cycle of full travel unless the block valve is closed with the power removed in order to meet the '

requirements of 3.4.4.b, 3.4.4.c, or 3.4.4.d. l !

i E

SUMMER -UNIT 1 3/4 4-10b Amendment No.

l

} ,

REACTOR COOLANT SYSTEM i

u BASES -

l

. J 3/4.4.2 SAFETY VALVES !

The pressurizer code safety valves operate to prevent the RCS from being l pressurized above its Safety Limit of 2735 psig. Each safety valve is designed to relieve 420,000 lbs per hour of saturated steam at the valve set point plus 3% accumulation. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur during shutdown. ,

In the event that no safety valves are OPERABLE, an operating RHR loop, connected to the RCS, provides overpressure relief capability and will prevent RCS over-pressurization. In addition, the Overpressure Protection System provides a '

diverse means of protection against RCS overpressurization at low temperatures. t During operation, all pressurizer code safety valves must be OPERA 8LE 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 l surge rate resulting from a complete loss of load assuming no reactor trip i until the first Reactor Protective System trip set point 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 be perfomed in I accordance with the provisions of Section XI of the ASME Boiler and Pressure j Code. j 3/4.4.3 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 SAR. The limit is consistent with the initial SAR assumptions.

The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months periodic surveillance is sufficient to ensure that the parameter i 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. The requirement that a minimum number of pressurizer heaters be OPERABLE ennances the capability of the plant to centrol Reactor Coolant System pressure and establish natural circulation.

3/4.4.4 RELIEF VALVES (PORV's)

. r operated relief valves and steam bubble function to r i pressure during a transients up to and includ s gn step load decrease with steam cump. Oper

~

operated relief valves j minimizes the undesirable o e spr't ressurizer code safety valves. Each a remotely operated block valve to sitive

t_, acability should a relief valve been=a ingp ngble.

ZNSMT BI SumER - UNIT 1 B 3/4 4-2 Amendment No. 94 m___.____. _ _. ,

Document Control Desk SCE&G -VCSNS TSP 950002 RC-95-0167 Page 1 of1 INSERTB1 3/4.4.4 RELIEF VALVES (PORVs)

The pressurizer power operated relief valves (PORVs) and steam bubble i function to relieve RCS pressure during all design transients up to and including !

the design step load decrease with steam dump. The PORVs and block valves may be used to depressurize the RCS when normal pressurizer spray is unavailable. Operation of the air operated PORVs minimizes the undesirable opening of the spnng loaded pressurizer code safety valves. Each PORV has a remote. controlled motor-o >erated block valve to provide a positive shutoff capabi should a relief va: ve become inoperable. The series arrangement of the POR and its associated block valve permit surveillance while at power.

l The PORVs, their block valves, and their controls are powered from buses !

that normally receive offsite power but are also capable of bemg powered from :

emergency power sources. Two PORVs and their associated blocx valves are i powered from two separate safety trains. By maintaining two PORVs and their . i associated block valves OPERABLE, redundant capability to perform their design function is maintained. j Plant operators employ the PORVs to depressurize the RCS in response to k

certain plant transients if normal pressurizer spray is not available. For the i

Steam Generator Tube Rupture (SGTR) event, the safety analysis assumes that ;

manual operator actions are required to mitigate the event. A loss of offsite power is assumed to accompany the event, and thus, normal pressurizer spray is unavailable to reduce RCS pressure. The PORVs are assumed to be used for RCS depressurization, which is one of the steps performed to equalize the primary and i secondary pressures in order to terminate the primary to secondary break flow I and the racioactive releases from the affected steam generator.

Credit is taken for the PORVs in safety analyses of events that result m !

mereasmg RCS pressure where de >arture from nucleate boiling ratio (DNBR) -

cntena are critical. By assuming PORV manual actuation, the primary pressure !

remains below the high pressurizer pressure trip setpoint, thus the DNBR '

calculation is more conservative. Events that assume this condition include a turbine trip and the loss of normal feedwater.

One PORV that is capable ofmanual operation has sufficient capacity :

to perform its function to depressurize the RCS and mitigate the effects of a postulated event. Two PORVs that are OPERABLE or capable of manual operation provide adequate redundancy.

I Operating the PORV and block valve through one complete cycle verifies that the valve and its associated supporting systems are capable of manual operation.

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I t

REACTOR COOLANTSYSTEM I i

BASES- {

3/4.4.2 SAFETY VALVES !

The pressurizer code safety valves operate to prevent the RCS from being .

pressurized above its Safety Limit of 2735 psig. Eac 1 safety valve is designed :

to relieve 420,000 lbs per hour of saturated steam at the valve set point p. .us '

3% accumulation. The relief capacity of a single safety valve is adequate to relieve any overpressure condition which could occur dun'ng shutdown. In the :

event that no safety valves are OPERABLE, an operating RHR loop, connected !

to the RCS, provides overpressure relief capability and will prevent RCS over- i pressurization. In addition, the Overpressure Protection System provides a .

diverse means of protection against RCS overpressurization at low temperatures. !

During operation, all pressurizer code safety valves must be OPERABLE t

- to prevent the RCS from being pressurized above its safety limit of 2735 psig.

The combined reliefcapacity of all of these valves is greater than the maximum ,

surge rate resulting from a complete loss ofload assuming no reactor trip i until the first Reactor Protective System trip set point is reached (i.e., no '

credit is taken for a direct reactor trip on the loss ofload) and also assuming !

no operation of the power operating relief valves or steam dump valves. :

~

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

3/4.4.3 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 SAR. The limit is consistent with the initial SAR assumptions.

The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months 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. The requirement that a minimum number of pressurizer heaters be OPERABLE enhances the capability of the plant to control bactor Coolant System pressure and establish natural circulation.

3/4.4.4 RELIEF VALVES (PORVs)

The pressurizer power operated relief valves (PORVs) and steam bubble function to relieve RCS pressure during all design transients up to and including the design step load decrease with steam dump. The PORVs and block valves may be used to depressurize the RCS when normal pressurizer spray is unavailable. Operation of the air operated PORVs minimizes the undesirable opening of the spnng loaded pressurizer code safety valves. Each PORV has a l i remote. .y controlled motor-owrated block valve to provide a positive shutoff

capability should a relief va: ve become inoperable. The series arrangement of

the PORV and its associated block valve permit surveillance while at power.

l SUMMER-UNITI B 3/4 4-2 Amendment No. 94,

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t

' REACTOR COOLANTSYSTEM BASES RELIEF VALVES (PORVs) (Continued)

The PORVs, their block valves, and their controls are powered from buses that normally receive offsite power but are also capable of bemg powered from emergency power sources. Two PORVs and their associated block valves are powered from two separate safety trains. By maintaining two PORVs and their associated block valves OPERABLE, redundant capability to perform their design function is maintained.

Plant operators employ the PORVs to depressurize the RCS in response to certain plant transients if normal pressurizer spray is not available. For the Steam Generator Tube Rupture (SGTR) event, the safety analysis assumes that manual operator actions are required to mitigate the event. A loss of offsite power is assumed to accompany the event, and thus, normal pressurizer spray is unavailable to reduce RCS pressure. The PORVs are assumed to be used for RCS depressurization, which is one of the steps performed to equalize the primary and secondary pressures in order to terminate the primary to secondary break flow and the radioactive releases from the affected steam generator.

Credit is taken for the PORVs in safety analyses of events that result in increasing RCS pressure where de aarture from nucleate boiling ratio (DNBR) criteria are critical. By assuming *ORV manual actuation, the primary pressure remains below the high pressurizer pressure trip setpoint, thus the DNBR calculation is more conservative. Events that assume this condition include i a turbine trip and the loss of normal feedwater.

One PORV that is capable of manual operation has sufficient capacity to perform its function to depressurize the RCS and mitigate the effects of a postulated event. Two PORVs that are OPERABLE or capable of manual operation provide adequate redundancy.

i Operating the PORV and block valve through one com 31ete cycle verifies that the valve and its associated supporting systems are capaile of manual operanon.

i J

SUMMER- UNIT 1 B 3/4 4 2a Amendment No.

J

,, ., ,.-,,..rm - , , .m, . .,-

Docum ntCentralD:sk

' Attachm:nt II TSP 950002 RC-95-0167 Page 1 of 2 SAFETY EVALUATION !

FOR REVISING THE SPECIFICATION FOR {

PRESSURIZER PCRV AND BLOCK VALVES IN THE l VIRGIL C. SUMMER NUCLEAR STATION t TECHNICAL SPECIFICATIONS j Description of Amendment Reauest

{

The Virgil C. Summer Nuclear Station (VCSNS) Technical Specifications (TS) !

3/4.4.4, RELIEF VALVES, is being revised to follow the guidance of Generic Letter !

(GL) 90-06 and the improved Westinghouse Standardized Technical Specifications.

The proposed technical specification change request (TSCR) will exaand the Action Statements, revise the Surveillance Requirements, and revise the Bases for the !

pressurizer Power Operated Relief Valves (PORVs) and block valves. l The Bases Section is being revised to provide additional design basis information. l' Due to the design basis function of these components, the PORV can be blocked and still be capable of performing its intended functions in manual control to mitigate the ;

event. This is true when power is maintained to the block valves. One such event is

the Steam Generator Tube Rupture where credit is taken for the PORVs as an ,

alternative method to depressurize the Reactor Coolant System (RCS). j One PORV is capable of performing the mitigating function for the event described l above. This change proposes to maintain at Least two out of three pressurizer PORVs !

OPERABLE orca ble ofbeing manually i

3. This differs sli tly from the guidance m, cycled at all times while in Modes 1,2, an be OPERABLE at a 1 times while in Modes 1,2, and 3. This same logic is also being applied to the block valves where the expectation is that at least two block valves will l be OPERABLE at all times while in Modes 1,2, and 3. !

The action statements are also being revised to redefine the mode in which this ;

specification does not apply and the time requirements to achieve this mode. t Previously, the action statement directed the plant to COLD SHUTDOWN, where !

HOT SHUTDOWN satisfies the requirements of this specification.

The surveillance requirements are being revised to define the testing that will verify l the OPERABILITY of the PORVs and block valves. The TS channel calibration is no j

- longer considered necessary for the OPERABILITY of the PORVs and has been deleted ;

in accordance with the Westinghouse Standardized Technical Specification (NUREG !

1431). ;

i Safety Evaluation i The design function of the pressurizer PORVs includes minimizing the challenges to l the pressurizer code safeties and the manual operation as an alternative method of ;

depressurizing the RCS. The only design basis accident that credits the use of the j pressurizer PORVs in coping with or mitigating the accident is the Steam Generator 1 Tube Rupture coincident with Loss of Offsite Power (LOOP).

]

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- Docum:nt Centrol Desk t AttachmentII TSP 950002 RC-95-0167

' Page 2 of 2 The Westinghouse Emerge y Responso Guidelines that provide guidance for the development ofEmergency ratq Procedures state that for the SGTR coincident with a LOOP,one PORV sh Id be opened to depressurize the RCS. During i valide. tion of the EOPs on the VCSNS simulator, it was demonstrated that one pressurizer PORV has sufficient capacity to depressurize the RCS and equalize the ' ,

pressure between the primary and secondary sides of the faulted steam generator, i Once the pressure is equalized, the flow of contamination and fission products into the secondary systems is ended, thus limitin g any release of radioactive steam to the ;

atmosphere. The analysis in Chapter 15 of tae VCSNS Final Safety Analysis Report

- (FSAR) shows that the dose received offsite from this accident is a small function of ,

that allowed under 10 CFR 100. :

The proposed TSCR would require a minimum of two pressurizer PORVs and their !

associated block valves to be OPERABLE or at least capable of being manually j cycled while in Modes 1,2, and 3. If this minimum number is not met, the plant l would have to go to a mode where this TS does not apply. This requirement would insure sufficient perform the intendedrelief capacity, functions. assuming It assures as well theloss of redundancy,ity to erform thew capabil '

req ed manual functions to mitigate the design basis accident as escribed in the ;

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Docum:nt Centrol Desk Attachment HI TSP 950002 RC-95-0167 Page 1 of 3 I

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SIGNIFICANT HAZARDS EVALUATION i FOR REVISING THE SPECIFICATION FOR ,

PRESSURIZER PORV. AND BLOCK VALVES IN THE VIRGIL C. SUMMER NUCLEAR STATION TECHNICAL SPECIFICATIONS ,

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Description of Amendment Request !

The Virgil C. Summer Nuclear Station (VCSNS) Technical Specifications (TS) 3/4.4.4, RELIEF VALVES, is being revised to follow the guidance of Generic Letter (GL) 90-06 and the improved Westinghouse Standardized Technical Specifications.

The proposed technical specification change request (TSCR) will exaand the Action Statements, revise the Surveillance Requirements, and revise the Lases for the pressurizer Power Operated Relief Valves (PORVs) and block valves.

The Bases Section is being revised to provide additional design basis information.

Due to the design basis function of these components, the PORV can be blocked and still be capable of performing its intended functions in manual control to suitigate the !

event. This is true when power is maintained to the block valves. One such event is the Steam Generator Tube Rupture where credit is taken for the PORVs as an alternative method to depressurize the Reactor Coolant System (RCS).

One PORV is capable of performing the mitigating function for the event described l above. This change proposes to maintain at Least two out of three pressurizer PORVs l OPERABLE or capable of being manually i

3. This differs slightly from the guidance m, cycled at all times while in Modes 1,2,!

be OPERABLE at all times while in Modes 1,2, and 3. This same logic is also being l applied to the block valves where the expectation is that at least two block valves will ,

be OPERABLE at all times while in Modes 1,2, and 3. !

The action statements are also being revised to redefine the mode in which this I specification does not apply and the time requirements to achieve this mode.

Previously, the action statement directed the plant to COLD SHUTDOWN, where HOT SHUTDOWN satisfies the requirements of this specification. l The surveillance requirements are being revised to define the testing that will verify the OPERABILITY of the PORVs and block valves. The TS channel calibration is no longer considered necessary for the OPERABILITY of the PORVs and has been deleted in accordance with tho Westingl ouse Standardized Technical Specification (NUREG 1431).

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.. Docum:nt Central Desk

~ AttachmentIII TSP 950002 '

RC-95-0167 Page 2 of3 ;

Basis for No Significant Hazards Consideration Determination South Carolina Eletric & Gas Company (SCE&G) has evaluated the proposed ,

changes to the VCSNS TS described above against the Significant Hazards Criteria of10 CFR 50.92 and has determined that the changes do not involve any significant :

hazard for the following reasons.

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1. The probability or consequences of an accident previously evaluated is not !

significantly increased.

i There is no increase in the probability of an accident because the physical i characteristics of the PORVs and their block valves remain unchanged. No !

changes to any hardware or software that affects these components is planned. ,

The PORVs are pressure relieving devices and only two failure modes need to be >

considered. The first is that one or more PORVs or block valves fail to open when i required. This is not a significant concern and is not a credible cause of any accident. The second mote is failing to close which includes depressurization of '

the RCS and a reactor trip on low pressurizer pressure or overtemperature AT.

The consequences for the more limiting Pressurizer Safety Valve Accidental ;

Depressurization event has been analyzed with acceptable results. ;

i There is no increase in the consequences of an accident as a result of this change, l because only one PORV is required to mitigate the consequences of a design basis -

Steam Generator Tube Rupture. There is sufficient redundancy to ensure one !

PORV is available to perform this function even if one PORV is inoperable or :

incapable of being manually cycled. The validation of the Emergenc,y Operating Procedures on the VCSNS simulator demonstrated that one pressurizer PORV :

has sufficient capacity to depressurize the RCS in a time frame which will not l cause the offsite doses presented in the FSAR to be exceeded. )

The PORVs are utilized to depressurize the RCS and equalize the pressure l between the primary and secondary systems. This stops the intrusion of RCS water into the secondary which can be released into the atmosphere. By the time ;

the PORVs are called upon, the affected steam generator (SG) has been identified ,

and steps have been taken to isolate the faultet SG. This acts to minimize the :

radiological impact on the health and safety of the public. In all cases, the dose results are within 10 CFR 100 limits.

2. The possibility of an accident or a malfunction of a different type than any previously evaluated is not created.

The proposed TSCR does not involve any physical changes to the plant or decrease the number of PORVs and block valves that must be capable of performing their intended function. These components are used to mitigate the effects of postulated events and their failure has already been considered. The worst case failure, either not opening or not closing, has been evaluated and is bounded by other more limiting accidents.

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1 Document Control Desk AttachmentIII TSP 950002 RC-95-0167 Page 3 of 3

3. The margin of safety has not been significantly reduced.

The currently approved TS permits all three PORVs and/or their block valves to be inoperable as :.ong as precautions are taken to assure that RCS would not leak-by, assuming single failures and spurious operation. The proposed TSCR 2 would require a minimum of two PORVs and block valves to be operable, or at least capable of being manually cycled, in Modes 1,2, and 3. This is in fact an increase in margin and provides for greater reliability with the added benefit that the probability of challengas to the pressurizer code safety valves will be lessened.

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