ML19345H123

Safety Evaluation of Vacuum Breaker air-operated Valves. Likelihood of LOCA Requiring Extensive Containment Spray Use W/Earthquake Exceeding Operational Basis Earthquake by 60% Found Very low.Marked-up Amend Application Encl

ML19345H123
Person / Time
Site:	Peach Bottom
Issue date:	04/14/1981
From:	Novak T Office of Nuclear Reactor Regulation
To:
Shared Package
ML19345H124	List: ML19345H123 ML19347E153
References
NUDOCS 8105010007
Download: ML19345H123 (4)

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NUCLEAR REGULATORY COMMISSION

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION PHILADELPHIA ELECTRIC COMPANY PEACH BOTTOM UNIT NO. 2 DOCKET NO. 50-277 Introduction The licensee (Philadelphia Electric Company - PECO) informed the NRC Operating Reactor Project Manager (ORPM) at 6:45 pm EST on April 13, 1981 that the vacuum breaker air-operated valves between the Peach Bottom Unit No. 2 Torus and the Reactor Building would be overstressed in the event of a design basis earthquake. PECO was aware of this at 5:00 pm on April 13, 1981. Technical Specification-(TS) 3.7.A. Primary Containment requires that Unit 2 will be placed in cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of the time both vacuum breakers are out of service. Unit 3 is currently in a refueling outage and PEC0 requested by letter dated April 14, 1981, telecopied to the NRC and received at 11:00 am EST that Unit 2 be permitted to continue operation beyond 5:00 pm April 14, 1981, otherwise TS 3.7.A would require cold shutdown of Unit 2.

Evaluation The defective component is a it5ctiiralbracket on the valve operator. The bracket will withstand an acceleration of.0.8g.

The operational basis earth-quake subjects the bracket to 0.5g; however, the desigrr basis earthquake subjects the bracket to 1.21.

Failure of both brackets might result in 9

failure of the air-operated vacuum breakers to function as designed. These valves protect the torus from extemal pressure loads that might be induced during a LOCA followed by manual initiation and continued operation of contain-ment sprays.

There is a very low likelihood of a LOCA that would require extensive use of the containment sprays, which are manually initiated and operated; concurrent with an earthquake that would exceed the operational basis earthquake by about 60%. We conclude based on the above, that Peach Bottom Unit No. 2 can be allowed to continue operation as long as one of the two valves is declared I

operational by 5:00 pm EST April 20, 1981. With one of the two valves operational l

the TS would pemit reactor operation for seven additional days to April 27, l

1981, 6:00 pm EDST; at that time if both valves are not restored to operability, j

Unit No. 2 will be placed in a cold shutdown condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

l Dated: 4/LA#% /98/

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BEFORE THE 1.7/-

UNITED STATES NUCLEAR REGULATORY COMMISSION 1.7 /l

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f In the Matter of 1.7/i Docket Nos. 50-277

1. 7 /i PHILADELPHIA ELECTRIC COMPANY 50-278

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APPLICATION FOR AMENDMENT

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i FACILITY OPERATTNG LICENSES 1.7 /f DPR-44 & DPR-56 1.7/k

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Philadelphia Electric Company, Lie ensee under Facility 1.7/

t Operating License DPR-44 for Peach Bottom Atomic Power Station Unit 2 1.7 q hereby requests that the Technical Specifications contained in j

Appendix A of the Operating License be temporarily amended by revising 1.7/I l

p certain sections as, indicated in the following discussion.

1.7/i At 5: 00 PM on 4 /13/81, Engineering informed the Peach Bottom 1.7 /-

1 Station that the air operated vacuum breaker valves between the

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1, Reactor Building; and the Unit 2 torus would be overstressed in the etcnt of the design basis earthquake.

This detereination is based on 1.7/

calculations performed by the valve reanufacturerjni'.i:h; 12.':r'ede-h'*

m The subject valves are operated on torus to 1 7/'

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P00R B M Reactor Building diff ential pressure.

Under this low pressure

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condition the air opeisted valves open, thereby permitting the vacuum breaker check yalves to function.

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Re specific defective component ie a bracket on the valve 1.7/

operator.

Yielding or failure of this bracket would cause the valve 1.7 /

to fail in an indeterminate position.

The braoket will withstand an 1.7/-

acceleration of 0.8 g.

The operational basis earthquake subject's' this

1. 7 / l bracket to 0.5g.

The design basis earthquake subjects this bracket to

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• 1 1.21 g.

The bracket herefore meets the operationa3 basis earthquake 1.7 /

• criteria with nargin.

The function of the vacuum breaker systes is to relieve?

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lL-negative pressure in the containment.

Normal operating pressure.Y'

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2 within containment is 0.5 psig +.25 psi.

The only occassions on-1.7/1 which the containment Vill experience negative pressure is during.

purging operations or during a LOCA followed by the manual initiation 1.7/1 of contairnent spray.

Purging of the drywell is restricted when the.

1. 7 /1 reactor is at power to 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> per year.

The probability therefore 1.7/1 l

of requiring this vacuum breaker. function is minimal.

The torus is equipped with two vacuum breaker systems, each 1.7/1 having 100% relier capacity for single spray loop operation.

The air t 1.7/1 operated valve in both vacuum breaker systems has similar seismic deficiencies.

The Technical Specification 3.7. A.3.b permit operation 1.7/1

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with 1 inoperable vacuum breaker system for a period of 7 days.

The 1.7/1 l.l Bases of the Technical Specifications indicates that operation for 30 4

l t l 5 days with a single vacuum breaker system inoperable is justifiable.

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I Based on the present design, valve A0-2502B can be upgraded

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!l to with:tand design basis earthquake require =ents by installction of a

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1 snubber.

It is c:pected that this installation will require 7 days.

1.7 / r U;tGrading of AO-2502A will require installation of a snubber cnd 1.7/1 l

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e ification of the present support systes.

This work is expected to 1. 7 / 11 j be accomplished within 14 days.

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Based on the fact that the,present instal on, will be 1.7/1 b

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' operable for the operational basis earthquake with margin h h 't.7/1

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, the low probability of a seismic event 'Wiich 1.7/1 exceeds this acceleration and the low probability of occurrance of a j

i LOCA which would require use of containment spray, we request 1.7/1 permission to continue operation during the 7 days required to repair 1.7 /1, the B valve and an additional 7 days to repair the A valve.

The Plant 1.7/1 Operations & Review Committee and some members of the Opgrations &

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Safety Review Committee have reviend this concern and have determined 1.7/1,-

that operation as requested is not an unreviewed safety q'uestion.-

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A formal request with complete review, proper fees,

1. 7/1j signatures and affidavits will be provided by April 16,1981.{A 1.7 /1 verbal concurrence from NRR is required by 5: 00 PM on April 14, 1981, 1

1 in order to avoid a Unit shutdown.

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'j NUCLEAR REGULATOctY COMMISSION wAswmcTom. o. c. 20ses

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April 17,1981

<s to Docket No. 50-277 0

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Mr. Edward G. Bauer, Jr.

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Vice President and General Counsel V

Philadelphia Electric Company 2301 Market Street t-4 Philadelphia, Pennsylvania 19101

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Dear Mr. Bauer:

This letter confirms the authorization issued orally by the NRC staff on April 14, 1981, telephone call from M. Fairtile, ORB #4 to C. Cowgill, NRC Resident Inspector and W. T. Ullrich, Station Superintendent for a temporary change to the Technical Specifications for Peach Bottom Atomic Power Station, Unit No. 2.

The temporary change permits Peach Bottom Unit 2 to continue operation for seven days from 5:00 PM, April 13,1981, to 5:00 PM, April 20, 1981, rather than going to cold shutdown within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of 5:00 PM, April 13, 1981, due to both of the torus-to-Reactor Building vacuum breakers being declared inoperable.

With one of the two vacuum breakers mede operational by 5:00 PM, April 20, 1981, Unit 2 could continue to operate to April 27, 1981, 6:00 PM EDST.

At that time continued operation will be permitted only if both vacuum treakers are operable. The temporary relief was authorized in response to your request by telecopied letter from W. M. Alden to M. B. Fairtile, NRC, dated April 14, 1981.

An official amendment and appropriate Federal Reg ster Notice will be i

forwarded in the near future.

Sincerely, b

TfFomas M. Novak, Assistant Director for Operating Reactors Division of Licensing cc:

See next page 8/OVP/C/ D

p.

Philadelphia Electric Company cc w/ enclosure (s):

Eugene J. Bradley U. S. Environmental Protection Agency Philadelphia Electric Company Region III Office Assistant General Counsel ATTN: EIS COORDINATOR 2301 Market Street Curtis Building (Sixth Floor)

Philadelphia, Pennsylvania 19101 6th and Walnut Streats Philadelphia, Pennsylvania 19106 Troy B. Conner, Jr.

1747 Pennsylvania Avenue, N.W.

M. J. Cooney, Superintendent Washington, D. C.

20006 Generation Division - Nuclear Philadelphia Electric Company Raymond L. Hovis, Esq.

2301 Market Street 35 South Duke Street Philadelphia, Pennsylvania 19101 York, Pennsylvania 17401 Government Publications Section Warren K. Rich, Esq.

State Library of Pennsylvania Assistant Attorrey General Education Building Department c... 6 ural Resources Comonwealth and Walnut Streets Annapolis, Maryland 21401 Harrisburg, Pennsylvania 17126 Philadelphia Electric Company ATTN: Mr. W. T. Ullrich Peach Bottom Atorr.ic Power Station Mr. R. A. Heiss, Coordinator Delta, Pennsylvania 17314 Pennsylvania State Clearinghouse Governor's Office of State Planning Albert R. Steel Chairman and Development l

Board of Supervisors P. O. Box 1323 Peach Bottom Township Harrisburg, Pennsylvania 17120 l

R. D. #1 Delta, Pennsylvania 17314 Curt Cowgill U.S. Nuclear Regulatory Comission Office of Inspection and Enforcement Peach Bottom Atomic Power Station P. O. Box 399 Delta, Pennsylvania 17314 l

Director, Criteria and Standards Division Office of Radiation Programs (ANR-460) l U. S. Environmental Protection Agency Washington, D. C.

20460

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