ML20148P495

Safety Evaluation Supporting Amends 110 & 99 to Licenses DPR-39 & DPR-48,respectively

ML20148P495
Person / Time
Site:	Zion  File:ZionSolutions icon.png
Issue date:	04/04/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20148P475	List: ML20148P488 ML20148P495
References
NUDOCS 8804110237
Download: ML20148P495 (4)

Text

.. -

/  %, UNITED 87 ATE 8 i 4

[ r NUCLEAH REGULATORY COMMISSION  ;

5 I wwasoTON, D. C. 20M5 '

\ . . . . . ,e

SAFETY EVALUATION BY THE OFFICE Of NUCLEAR REACTOR REGULATION RELATED TO AMENOMEhT NO 110 TO FACILITY OPERATING LICENSE NO. OPR-39 ANO

AMENDMENTNO.99TOFACILITYOPERATINGLICENSENO.OPR-g l COMMONWEALTH EDISON 004pANY

ZION NUCLEAR POWER STATION, UNITS 1 AND 2 l

DOCKET NOS. 50-295 AND 50-304 '

j

1.0 INTRODUCTION

l By letter dated May 29. 1987 from P. C. LeBlond. Commonwealth Edison

Company (CECO) to USNRC Ceco Overpressure Protection (LTOP) proposed of thechanges to the Low Temperature

~

section Technical Specification.

Additional information and clarification was given to the staff in a letter dated January 21, 1968 from P. C. LeBlond (Ceco) to USNRC.

2.0 EVALUATION i

The proposed change is intended to reflect the guidat.ce given in StandardTechnicalSpecification(STS)NUREG-0452. Revision 4.Section 3.4.9.3 which identifies two methods for low temperature o'verpressure protection.

l A. Two power operated relief valves (PORV) must be operable, or (

B. Thereactorcoolantsystem(RCS)istobedepressurizedwithanopen '

j vent path.

4

) Both the current Zion Technical Specifications and the pinposed amendment j include the above two options, with the substitution of an open PORV for the specified RCS vent. In addition, the proposed amendment includes the j '

d option to permit RCS pressure to be reduced to less than 100 psig

concurrent with pressurizer level less than 25%.

! All three methods discusseu above currently exist in the Zion Technical Specifications. The basis for these methods are contained on page 94 of f

the existing Technical Specifications. Thus, this proposed amendment a does not explicitly involve the ap;,rova? of new low temperature l overpressue protection methcds.

The proposed changes follow the STS, and there is no major change in the LTOP methods included in the present Technical Specification. Therefore, j the proposed Tcchnical Specification chcnges in Section 3.3.2.G.1 and 4.3.2.G.1 are acceptable. ,

i p DR P

2 The proposed anendment has included the restrictions en charging pump,  ;

safety injection pump, and accumulator operation. However, the -

flexibility to allow two charging pumps to operate for short periods of time for the purpose of maintain 1Hg seal injection flow to the reactor l coolant pumps has been added. The purpose of this clause is to maintain I the cleaner seal injection flow to the Reactor Coolant Pump (RCP) seals during charging pump realignment. This will water through the Reactor Coolant Pump (RCP) sealsprevent theseal when the backflow of RCS injection flow has been interrupted which will help prevent RCP seal failure.

The amount of time during which two charging pumps will be operated simultaneously is small, only about 5 minutes. Moreover in the typical '

LTOP analysis, oper: tion of only one safety injection pump is assumed.

The design flow capacity of the safety injectior: pump (400 than twice the design flow capacity of the charging pumps (gpm) is more 150gpm)

(Ref: USAR Table 6.2.2-5). Therefore, the operation of cwo charging pumps

.! will be bounded by the LTOP analysis. Hence the proposed change in Technical Specification sections 3.3.2.G.2 and 4.3.2.G.2 allowing simultaneous operation of two charging pumps for a short duration of tim is acceptable.

The guidance from STS Sectior, 3.4.9.3 indicates that the PCS be vented within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> following the inoperability of ont PORY for greater than 7 days,or the inoperability of two PORV's. The proposed amendment incorporatas 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />, respectively, for venting the RCS subsequent to the above conditions.

This variance from the STS reflects operating experience of the Zion Station which shows that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> provides a more realistic time period to accomplish the cooling and depressurization transient in a controlled manner. The initial conditions for such an operation would include a steam bubble within the pressurizer. Spiecifically, the process to be followed for a plant cooldown is out11ned in GOP-4 "Plant Shutdown and

Ccoldown." This procedure requires 50*F/hr RCs cooldown rete and also requires the performance of several tests (some at the discretion of l 1

l the Shift Engineer or Operating Engineer) during the cooldoen process. l Historically, the cooldown process from 100% power conditions of 559'F/

2235 psig to cold shutdown conditions of 200*F/400 psig takes approx-t imately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. Another 6 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> is required to plac9 the plant 1

in conditions of 100 psig/ pressurizer level 25%. This is the methodology that Zion proposes for responding to one inoperable PORV.

l Zion recognizes that 2 inoperable PORY's pose a more serious plant condition. "ihe plant would still follow the guidance of GOP-4, ottitting Some of the optional stips of the procedure, and consequently cooldown i i

in an expedited manner. This process woulti take approximately 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />.

i l

l 1

. \

. i 1

3 1 l

l The staff agrees that maintaining controlled plant conditions during a  !

transient, as demonstrated by the operational experience at Zion Station, is important especially when the plant is in a degraded condition. In ,

addition, the 16-hour time period is more restrictive than the 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />  !

allowed the existing Zion Technical Specifications. Based on the above, the staff finds the Technical Specification change in section 3.3.2.G.3 acc6ptable. l The STS incorporates the requirement for the perfonnance of ASME boiler and pressure code surveillances in the PORY Technical Specification i section. The existing Zion specifications address these test requirements j in Section 3.3.2.E. Therefore, they are not repeated in this proposed i a"endtren t. l 1

1NICAL FINDING e following proposed changes are acceptable for the reason given above. I

1. Reformatting Zion Technical Specification sections 3.3.2.G and 4.3.2.G to STS format.

2. Incorporating flexibility to allow the operation of two centrifugal ,

charging pumps for short periods of time during the realignment of 1 operating charging pumps. l

3. Clarifying the allowable time period for depressurizing the RCS following the failure of PORVs.

4.0 E,NVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of the  :

facilities component located with the restricted areas as defined in l 10 CFR 20e The staff has determined that these amendments involve 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 Comission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public coment on such finding.

Accordingly, these amendments meet the eligibility criteria for categorical l

exclusionsetforthin10CFR51.22(c)(9). Pursuant to 10 CFR 51.22(b), i no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments.

5.0 CONCLUSION

l The staff has concluded, based on the consideration discussed above, that:

(1) there is reasonable assurance that the health and safety of the public

l l l l

4 l 1

l will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Comission's regula-tions and the issuance of these amendments will be not inimical to the coninon defense and security or to the health and safety of the public.

I Principal Contributor: G. Thomas l Dated: April 4. 19R8 I

l l

l 1

. __ , ,,w --,.v-y-.m. r v----