ML20087D821

Safety Evaluation Supporting Amend 75 to License NPF-57

ML20087D821
Person / Time
Site:	Hope Creek
Issue date:	08/01/1995
From:	NRC (Affiliation Not Assigned)
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NUDOCS 9508110178
Download: ML20087D821 (8)

Text

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NUCLEAR REGULATORY. COMMISSION WASHINGTON, D.C. 20006 0001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMEN 0 MENT NO. 75 TO FACILITY OPERATING LICENSE NO. NPF-57 PUBLIC SERJICE ELECTRIC & GAS COMPANY ATLANTIC CITY ELECTRIC COMP /El HOPE CREEK GENERATING STATION DOCKET NO. 50-354

1.0 INTRODUCTION

By letter dated July 27, 1994, as supplemented May 26, July 10, and July 25, 1995, the Public Service Electric & Gas Company (PSE&G), _ the licensee, submitted a request for changes to the Hope Creek Generating Station, Technical Specification (TS). The July 10, 1995 letter submitted revised, re-typed Technical Specification pages. The revised, re-typed Technical Specification pages reflect proposed changes to those Technical Specification pages which were transmitted via PSE&G's original _ submittal on July 27, 1994 and in response to a request for additional information dated May 26, 1995.

. In addition, the revised, re-tynd pages reflect proposed changes which were discussed between PSE&G, the NRR Hope Creek Project Manager, and NRR technical reviewers at a May 5,'1995 meeting at NRR Headquarters and during subsequent teleconferences. The supplemental letters did not change the original no significant hazards consideration determination nor the original Federal Reaister notice. The changes requested in the July 27, 1994 submittal, as supplemented May 26, July 10, and July 25, 1995, would revise:

A.

1) TS 3.7.1.1 to establish following ACTION and Allowed Out-of-Service 1

times (A0Ts) for inoperable Safety Auxiliaries cooling System _(SACS) pumps:

a.

30 days for one SACS pump; t

b.

With one entire SACS subsystem inoperable, realign at least one (instead of both as currently required) of the affected diesel generators to the OPERABLE SACS subsystem. (Note: The 72-hour _ time period to restore the inoperable subsystem to OPERABLE status with at least one OPERABLE pump and heat exchanger to remain the same);

' and c.

72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for one SACS pump in each subsystem inoperable.

2) TS 3.7.1.1 by deleting a reference.to Specification 3.4.9.1.

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3) TS 3.7.1.1 ACTION Statements b, c and d to specify that two inoperabh SACS pumps in the SACS subsystem make the associated RHR loop or associated safety system inoperable. TS 3./.1.2 to establish a 30-day A0T'for'one inoperable Station Service Watse System (SSWS) pump.

B.

1) TS 3.8.1.1 to establish the following A0Te for inoperable onsite AC electrical power sources'14 days for eithen C or D Emergency Diesel Generator (EDG) inoperat le.

r C.

1) TS Surveillance Requirement 4.8.1.1.2.h to permit online maintsnance and inspection of the C and D EDGs.

2.0 EVALUATION A.

Extended Outage Times for Cooling Water Systems t-The SSWS provides cooling water from the ultimate heat sink (UHS) to the SACS i

heat exchangers and the reactor auxiliaries cooling system (RACS) heat t

exchangers during normal operation and during a loss of offsite power.

Following a loss of coolant accident (LOCA) or other design basis accident, cooling is supplied only to the SACS heat exchangers. The SSWS consists of two loops (Loop A and Loop B) with two motor-driven pumps per loop. Each SSWS loop cools a separate SACS loop (via two parallel SACS heat exchangers per SSWS loop), and either SSWS loop can provide cooling for the RACS heat i

exchangers.

SSWS Loop A supplies cooling water to SACS heat exchangers Al and A2, while SSWS loop B supplies SACS heat exchangers B1 and B2. Motor-operated cross-tie valves provide a flow path to the RACS heat exchangers during normal operation and provide a means of cross-connecting the SSWS loops for SACS heat exchanger supply. The only essential SSWS cooling water loads required for 4

safe shutdown are the SACS heat exchangers.

In the event of a LOCA, the SSWS cross-tie valves automatically close isolating the loops from each other and from the RACS-heat exchangers.

The current A0T for one inoperable SSWS pump is 7 days. However, based on engineering evaluations, with one SSWS pump inoperable, the SSWS is still 4

capable of performing all of its design basis safety functions with any additional single active failure. Under these conditions the additional failure of another pump or its associated EDG would result in either two SSWS pumps in one loop, or one SSWS pump in each loop. Therefore, since the SSWS can still meet its safety design basis with one inoperable pump, the licensee proposed to revise TS 3.7.1.2 to provide an A0T of 30 days for one pump inoperable. The 30 days is acceptable based on engineering judgment and operating experience plus the staff's approval of 30-day A0Ts for other 1

safety-related systems having redundancy beyond that which is required to meet the single active failure criterion. The 30 days is also consistent with the A0T for similar cooling water systems in NUREG-1433, the General Electric BWR/4 Standard Technical Specification (STS). Based on these considerations, the staff concludes that the proposed change to 30 days is acceptable.

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. i The SACS is one of two subsystems of the safety and turbine auxiliaries cooling system (STACS); both of which use the SACS pumps during normal operation.

"he other subsystem is the turbine auxiliaries cooling system (TACS) which is supplied by a common header from either loop of the SACS.

The TACS has no pumps of its own and uses the SACS pumps when it is in operation.

The SACS, like the'SSWS, is designed to operate under normal, shutdown, and design basis accident conditions. During all conditions, the SACS provides cooling water to the engineered safety features (EFS) equipment, including the residual heat renoval (RHR) heat exchangers, diesel generator coolers, and RHR pump seal and bearing coolers. On receipt of a LOCA signal, loss of power, or a low-low-low expansion tank level, the TACS is automatically isolated from the SACS loops via redundant isolation systems.

The SACS is divided into two closed loops, Loop A and Loop B (corresponding to Loops A and B of the SSWS, respectively), with two pumps, two heat exchangers, and one expansion tank in each loop. The two SACS loops normally operate independently with the TACS being supplied by only one of the SACS loops.

The SACS loops can be cross-connected by the TACS isolation valves.

There are two TACS isolation valves per SACS loop, for a total of four. Normally, two of the valves from one loop are open while the two from the other loop are maintained closed making the SACS loops independent of each other.

The current TS 3.7.1.1 for the SACS, has a 72-hour A0T for one inoperable SACS pump or one inoperable heat exchanger.

The proposed changes would provide an A0T of 30 days for an inoperable SACS pump and maintain 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for an inoperable heat exchanger.

The licensee's justification for increasing the A0T from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 30 days for an inoperable pump is based, in part, on the capability of the SACS to still meet the single active failure criterion with any one SACS pump inoperable.

This is basically the same technical justification as was used for the SSWS. The 30 days is an acceptable outage duration for the same reasons identified above for the SSWS pump regarding operating experience and other similar safety systems.

Based on the SACS's capability to meet its safety design basis with only three operable SACS pumps, the staff concludes that the proposed change is acceptable.

The current TS 3.7.1.1 also requires immediate measures to shutdown the plant in the event that one SACS pump or one heat exchanger in each loop becomes inoperable.

The licensee has proposed a 72-hour A0T in the event of one inoperable cump in each loop. As proposed, the A0T for one inoperable heat exchanger in each loop would remain the same. With one SACS pump in each loop operabie, the SACS can still meet all of its safety design bases assuming there are no other single failures. The 72-hour A0T is consistent with A0Ts for other engineered safety features (ESF) systems at Hope Creek and other light water reactor plants where the system can still meet all of its safety i

design bases, assuming no further single failures.

Immediate shutdown is I

usually required via TS 3.0.3 when a system can no longer meet its safety design basis for a design basis accident.

The proposed A0T is also consistent with the A0Ts in NUREG-1433 for systems with similar capability.

Therefore, based on the low probability of a design basis accident coupled with a single failure during the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> that the plant would be allowed to continue

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operation, the staff concludes that the proposed A0T is acceptable.

. _ ~. _ _ _ _ _ _ _

. In order to avoid unacceptable overlapping outages among the SACS, SSWS and the EDGs, the licensee added footnotes to TSs 3.7.1.1 and 3.7.1.2, that will ensure at least two associated EDGs, SACS pumps, and SSWS pumps will always be available. These footnotes, as clarified in the licensee's May 26, 1995 submittal, are acceptable because they ensure at least the minimum combination of pumps and emergency power supplies will be available to provide adequate heat removal for all design basis events, including a LOCA coincident with a loss of offsite power.

The present Action a.2 of TS 3.7.1.1, specifies that with one SACS loop inoperable, realign the affected EDGs to the operable SACS loop within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The proposed changes would specify to realign at least one of the affected EDGs to the operable SACS loop. Thus, if one of the EDGs cannot be realigned for one reason or another, it would be declared inoperable and the appropriate EDG inoperable action statement would be entered.

This is how the current TS wording is interpreted and the staff believes it is the correct interpretation.

Therefore, the proposed change is not considered a change, but a clarification of the existing TS and is, therefore, acceptable.

Current TS 3.7.1.1, Actions b (Mode 3 or 4), c (Modes 4 or 5), and d (Mode 5),

specify that the associated RHR loop, and/or associated safety-related equipment (depending on the operating Mode) of an inoperable SACS loop should be declared inoperable.

The proposed changes clarify that a SACS loop may be considered operable if it has one operable SACS pump and two SACS heat exchangers.

Thus, with only one inoperable SACS pump in a loop, the associated RHR and/or safety-related equipment does not have to be declared inoperable. The proposed changes are acceptable as they are supported by the plant safety analysis, whereby a SACS loop is capable of performing its safety design basis with one SACS pump and two SACS heat exchangers operable.

In support of the proposed changes the licensee performed probabilistic safety assessment (PSA) analyses to determine the increase in risk associated with the TS changes proposed for the SACS and the SSWS.

For that assessment, risk increases of s IE-6 were considered by the licensee to be insignificant and were used as a criterion to determine if an A0T extension was acceptable. As a result of the PSA, the licensee concluded that the proposed changes do not pose any significant increase in overall plant risk.

The staff reviewed the results of the licawa's analyses, including the methodology used, and concurs with the licensee's conclusions relative to the increased risk associated with the proposed TS changes for the SACS and SSWS.

B.

Revise A0T for EDGs and Provide for EDG On-line Maintenance 1). EDG A0T Extension for One EDG Inoperable In the submittal dated July 27, 1994, the licensee requested that the 72-l hour A0T for one EDG inoperable be extended to 30 days.

The licensee used

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PRA to show that the onsite power system retains full capability to effect a safe shutdown and to mitigate the effects of a design-basis accident.

l The results of the PRA indicated that establishing a 30-day A0T for one

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. I inoperable EDG yielded an overall risk increase in core damage frequency of 7.23 E-7.

The licensee stated that the reason for the change in the EDG A0T is to obtain operational flexibility and reduce the chance of plant shutdown. Additionally, the licensee stated that the extended A0T would improve maintenance quality through the alleviation of the constraints of completing work in a short 72-hour time interval. Although the PRA analysis submitted by the licensee appears to support a 30-day A0T extension, the staff is of the opinion that PRA alone should not be used as a basis for granting an A0T extension. The staff agrees that PRA is a useful analytical tool, however it needs to be used in conjunction with other technical considerations and good engineering judgment.

The staff believes that if an EDG was allowed to be out for 30 days, it might not get the attention that is required to maintain its reliability and availability to respond to emergencies and that 14 days is sufficient time to perform most maintenance activities. This length of time is based on industry experience (13.5 days considering two shifts working 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> a shift for a total of 216 hours0.0025 days <br />0.06 hours <br />3.571429e-4 weeks <br />8.2188e-5 months <br />). Therefore, the staff has determined that 14 days should be considered as the maximum A0T on a permanent basis and On EDG A0T extension beyond 14 days should be considered only on a one-time basis.

At Hope Creek Generating Station, the Class-lE AC power supply system is divided into four independent power supply channels.

Each of these four channels supplies loads in its own load group and has a dedicated EDG (EDG A, B, C, and D). All Class-lE loads are assigned to these channels so that any combination of three-out-of-four load groups has the capability to supply the minimum required safety loads to safely shut down the unit and mitigate the consequences of a design-basis accident. Under loss of offsite power (LOOP) conditions, either EDG A or B and any other diesel generator would be required to mitigate the consequences of a LOOP.

This is because residual heat removal (RHR) pumps A (powered from EDGA) or B (powered from EDGB) would be required to facilitate desired residual heat removal during a LOOP.

Because of the greater importance of EDGs A and B, the staff is concerned with extending the A0T for these EDGs. As a result, the staff informed the licensee that a maximum of 14 days (rather than 30 days) A0T will be allowed for EDGs C and D only, provided certain conditions are met.

EDGs A and B will continue to have a 72-hour A0T. Subsequently, in a letter dated July 10, 1995, the licensee revised its proposal to extend the A0T to 14 days for EDGs C and D only.

The conclusion to grant the 14-day A0T extension for EDG C and D is based on the licensee satisfying the following conditions:

a.

The licensee should verify through TS, procedures, or detailed analysis that the required systems, subsystems, trains, components, I

and devices that are required to mitigate the consequences of an l

accident are available and operable before removing an EDG for

4

, I extended preventive maintenance (PM).

In addition,-positive measures should be provided to preclude subsequent : testing or maintenance activities on_these. systems, subsystems, trains, components, and devices while the EDG is inoperable.

l b.

When EDG C or D is removed from service for an extended 14-day A0T, any two of the remaining EDGs must be capable, operable, and_ available to mitigate the consequences of a LOOP condition.

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c.

The removal from service of safety systems and important non-safety -

equipment, including offsite power sources, should be minimized during-H the extended 14-day A0T..

d.

Entry into this'14-day LC0 action statement should not be abused by repeated voluntary-entry into and exit from the LCO. To clarify the use of the extended A0T the licensee will add the following insert to the Hope Creek TS bases:

"The primary intent of the extending EDG A0T is that the extended EDG A0T from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days may be needed to perform preplanned EDG maintenance such as teardowns and modifications i

that would otherwise extend beyond the original 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> A0T."

e.

Voluntary entry into.this LCO action statement should not be' scheduled if adverse weather conditions are expected.

f.

The overall unavailability of the EDG should not exceed the value that 1

was used in the PRA supporting the proposed A0T.

g.

Any component testing or maintenance that increases the likelihood.of.

a plant transient should be avoided.

Plant operation should be' stable during the extended 14-day A0T.

In a letter dated July 25, 1995, tiie licensee supplemented its application and agreed to revise the TS' Bases to include the'above conditions.

2)

EDG A0T Extension for Two EDGs Inoperable In the submittal dated July 27, 1994, the licensee also requestert an extension of the A0T for two inoperable EDGs from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The result of the PRA analysis by the licensee established an overall risk increase in core damage frequency of 4.32 E-7 for the A0T 'of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for two EDGs inoperable. Although the PRA number was found to-be acceptable, the staff feels that 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> A0T in this configuration is too long due to the inability of the remaining EDGs at Hope Creek Generating Station to

, mitigate the consequences of an accident.

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1 At Hope Creek, three out of four EDGs are required to mitigate the consequences of an accident.

If Hope Creek was allowed to remove two EDGs from service for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, the remaining EDGs would not have the capacity to mitigate the consequences of an accident during this extended A0T.

Although, the PRA support this extension of the EDG A0T of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> for two inoperable EDGs, the staff feels.that prudent engineering judgment 1

cannot allow the extension of this EDG A0T beyond the current 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

Therefore, the staff finds the licensee's July 27, 1994, proposal to change the A0T for two EDGs inoperable from 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> unacceptable. The licensee's Jul 10, 1995, letter supplemented its i

application and transmitted revised TS change pages to reflect maintaining l

the A0T at 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

3)

EDG On-line Maintenance At Hope Creek, the existing TS Surveillance Requirement (SR) 4.8.1.1.2.h.1 stipulates that the EDG must have an inspection in accordance with the manufacturer's recommendations every 18 months "during shutdown." This surveillance has recently been removed from the Hope Creek TS (License Amendment No. 74, dated June 29,1995) and relocated to the Hope Creek Preventative Maintenance Program, where it will be controlled by the 10 CFR 50.59 process. The licensee has proposed to perform this inspection at power and remove the word "during shutdown" from this surveillance.

The licensee feels that this would allow more time to perform maintenance that must be performed at shutdown.

The licensee states that performing EDG on-line maintenance will provide significant operational benefits and will be performed in a manner that does not degrade net safety.

Additionally, the licensee states that the 18-month teardown and inspection can be performed on-line within system configurations and administrative guidelines, can be completed within a single LC0 entry, and will improve the reliability of the diesel generators.

Thrs NRC staff has been considering the extensions of the EDG A0Ts on a plant-specific basis if the primary intent of the extending EDG A0T is to perform 18 months of man.fr.cturer-recommended inspections such as teardowns and modification: that would otherwise extend beyond the original A0T. As stated in Section I of this evaluation,' the staff has found it acceptable, basec on the Hope Creek EDG configuration and certain conditions, to extend the A0T for EDGs C & D from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 14 days.

The licensee's July 10, 1995, letter supplemented its application and transmitted revised TS change pages to reflect a 14-day A0T for the C and v

D EDGs only.

TS Page B 3/4 8-1, Bases-Electrical Power Systems, transmitted by the licensee on July 10, 1995, was found to have omitted a reference to Regulatory Guide 1.108.

The licensee furnished a corrected page for this administrative error. This correction was found to be acceptable by the staff.

3.0 STATE CONSULTATION

In accordance with the Commission's regulations, the New Jersey State Official was notified of the proposed issuance of the amendment. The State official had no comments.

4.0 ENVIRONMENTAL CONSIDERATION

The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.

The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (59 FR 45033). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).

Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

5.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that:

(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributors:

M. Pratt W. LeFave Date:

August 1, 1995 e - - -.

,