ML20153E533

Safety Evaluation Supporting Amends 31 & 30 to Licenses DPR-80 & DPR-82,respectively

ML20153E533
Person / Time
Site:	Diablo Canyon
Issue date:	08/29/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20153E519	List: ML20153E527 ML20153E533 ML20195G551
References
NUDOCS 8809060343
Download: ML20153E533 (3)

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UNITED STATES

-l NUCLEAR REGULATORY COMMIS810N i

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l

RELATED TO AMENDMENT NO. 31 TO FACILITY OPFRATING LICENSE NO. OPR-80 1

4 AND AMENDMENT NO. 30 TO FACILITY OPERATING LICENSE NO. OPR-82 l

l PACIFIC GAS AND ELECTRIC COMPANY l

DIABLO CANYON NUCLEAR POWER PLANT. UNIT N05. 1 AND 2 i

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DOCKET NO. 50-275 AND 50-323 l

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1.0 INTRODUCTION

By letter deud October 29, 1986, as supplemented by letter dated l

a July 5,1988 (Reference LAR 86-11)

Pacific Gas and Electric Company (PG&E or the licensee) requested amendments to the Technical Specifi-l cations appended to Facility Operating License Nos. DPR-80 and DPR-82 for the Diablo Canyon Nuclear Power Plant, Unit Nos.1 and 2.

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proposed amendments would decrease the maximum closure time for the l

containment vacuum / overpressure relief valves from 10 seconds to 5 seconds.

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l 2.0 DISCUSSION l

l The staff reported its evaluation of the Diablo Canyon Unit 1 and Unit 2 f

j containment isolation dependability with regard to NUREG-0737. Item l

II.E.4.2 in Supplemental Safety Evaluation Report (SSER) 9 (June 1980),

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SSER 14 (April 1981), and $$ER 31 (April 1985). With respect to contain-L j

ment purge and vent valve operability (Position 6 of !!.E.4.2), it is i

1 necessary to demonstrate the operability of these valves during a design l

I basis accident in order to assure containment isolation. This demon-stration of operability is reconnended by Standard Review Plan (SRP) 6.2.4, l

Branch Technical Position (BTP) CSB 6-4, and SRP 3.10 for containment purge l

and vent valves which are not sealed closed during Modes 1, 2, 3 and 4.

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In $$ERs 14 and 31, the staff required that the Izainch vacuusi/ overpressure L

i relief valves be limited to opening angles of 50 degrees or less until their operability under accident conditions had been fully demonstrated.

Accordingly, a license condition to this effect was included in the l

operating license for both units, and the 10-second closing time was accepted pending an analysis of full qualification at a 5 second closing rate.

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i 8809060343 880029 DR ADCCK 050 5

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In its October 29, 1986 application for amendments, PGAE provided infonnation to demonstrate operability of the 12-inch containment vacuum / overpressure relief valves. The infonnation was reviewed by our I

contractor EG8G, who prepared the attached Technical Evaluation Report (TER), "Demonstration of Containment Yacuum/0verpressure Relief Yalve Operability". EGG-NTA-7841, dated September 1987. We have reviewed this report and agree with its conclusion that the Diablo Canyon relief valves i

are qualified to properly close against the buildup of containment pressure in the event of a design-basis loss-of-coolant accident, provided that the 12-inch valves are limited to a 50' opening as was assumed in the licensee's analysis. The requirement to limit the opening to 50' is already included in technical specification 3.6.1.7 for both units, thereby satisfying license conditions 2.C(6)g. for Unit 1 and license condition 2.C.(5)b. for Unit 2 which state the same requirement. Thus, j

the limitation on valve opening that was thought to be temporary is now 1

permanent.

The decrease in the valve closure time will ensure earlier containment isolation and thus will reduce the radiological censequences following a LOCA. Therefore, the more rapid closure is more conservative from the standpoint of offsite releases. The 5-second valve closure time is consistent with Branch Technical Position CSB 6-4 Item B.lf, and Standard Review Plan Section 6.2.4.

j By letter dated July 5,1988, the licensee provided additional analyses revising the evaluation given in the October 29, 1986 letter. However, the revised evaluation did not change the conclusions reached in the

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earlier evaluation, nor the staff's conclusions on this issue.

j Based on the above, the staff finds the proposed TS change to reduce the closure time for the containment vacuum / overpressure relief valves from 10 seconds to 5 seconds to be acceptable.

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3.0 ENVIRONMENTAL CONSIDERATION

i These amendments involve changes in the installation or use of facility components located within the restricted area as defined in 10 CFR Part

20. We have determined that the amendments involve no significant increase 1

E the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase

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in individual or cumulative occupational radiation exposure. The Comission j

has previously issued a proposed finding that the amendments involve no i

significant hazards consideration and there has been no public coasnent on I

such finding. Accordingly, these amendments meet the eligibility l

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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 these amendments.

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i 4.0 CONTACT WITH STATE OFFICIAL The NRC staff has advised the Chief of the Radiological Health Branch, State Department of Health Services, State of California, of the proposed determination of no significant hazards consideration. No coments were received.

5.0 CONCLUSION

We have 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, and 1

(2) such activities will be conducted in compliance with the Comission's regulations and (3) the issuance of these amendments will not be inimical l

to the connon defense and security or the health and safety of the public.

Principal Contributors: Chang-Yang Li Goutam Bagchi Charles M. Trammell i

Harry Rood Dated: August 29, 1988

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