ML18139C018

Safety Evaluation Concluding That Reasonable Assurance of Auxiliary Feedwater Sys Capability to Withstand SSE Exists

ML18139C018
Person / Time
Site:	Surry
Issue date:	08/20/1982
From:	NRC
To:
Shared Package
ML18139C017	List: ML18139C016 ML18139C018
References
GL-81-14, NUDOCS 8209130447
Download: ML18139C018 (6)

Text

{{#Wiki_filter:1.'. I** i; J \\ ~ -{ Introduction SURRY UNITS l AND 2 SEISMIC QUALIFICATION OF THE AUXILIARY FEEDWATER SYSTEM Since the accident at Three Mile Island attention has been focused on the ability of pressurized water reactors to provide reliable decay heat removal. While it is recognized that alternate methods may be available to remove decay heat following transients or accidents, heat removal. via the steam generators is the first choice for accomplishing a safe shutdown of the plant. Therefore, there should be reasonable assurance that the auxiliary feedwater system (AFW) can withstand the postulated Safe Shutdown Earthquake (SSE), consistent with other safety-related systems in the pl ant. To address this concern, the NRC developed and initiated Multiplant Action C-14, 11Seismic Qualification of Auxiliary Feedwater Systems." The objective of this plan is to increase, to the extent practicable, the capability of those plants without seismically qualified AFW to withstand earthquakes up to the SSE level. This program was implemented with the issuance of NRC Generic Letter 81-14, dated February 10, 1981. Our review of the licensee*s responses to this letter is the subject of this evaluation. Evaluation The enclosed report was prepared for us by our consultant, Lawrence Livermore National Laboratory, as part of our technical assistance contract program. The report provides their technical evaluation of the licensee's conformance to the requirements of Generic Letter 81-14. We have reviewed the consultant's report and concur with its conclusions. Subsequent to the consultant's technical review, we have had two telephone conferences (8/4/82 and 8/6/82) in which the licensee stated that the branch piping that affects the boundary (i.e., 3/4 inch vents and drains) is supported s.eismically for an SSE. We conclude, therefore, that. the boundary does in fact satisfy GL 81-14. Conclusion Based upon.our review of the consultant's technical evaluation report, we' conclude that there is reasonable assurance that the auxiliary feedwater.- system has sufficient capability to withstand a safe shutdown earthquake and accomplish its safety function. Accordingly, we are not contemplating requiring any seismic upgrading of this system under the NRC Multiplant Acticn C-14 program. We consider the consultant's report to be final, fn that no further tech-nical effort is required. 8209130447 8208'::>() PDR ADOCK 05000280 p PDR

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T~NICAL EVAULATION REPORT e SURRY NUCLEAR PLANT UNITS 1 ana 2 SEISMIC QUALIFICATION OF AUXILIARY FEEDWATER SYSTEM

l. INTRODUCTION Since the accident at Three Mili Island, considerable attention has been focuseo on the capability of nuclear power plants to reli~bly remove decay heat.

The NRC has recently undertaken Multip1ant Action* Plan C-14 "Seismic Qualification of AFW Systems" [Ref. 1], which is the subject of this evaluation. To implement the first phase of Action Plan C-14, the NRC issued Generic Letter No. 81-14 "Seismic Qualification of AF\\rJ Systems" [Ref. 2], dated February 10, 1981, to all operating PWR licensees. This letter requested each licensee (1) to conouct a walk~down of non-seismically qualified portions of* the AF~ system and iaentify deficiencies amenable to simple actions to improve seismic resistance, and (2) to provide design information regarding the seismic capability of the AFW system to facilitate NRC backfit decisions. . The licensee of Surry Units 1 and 2 responded with letter dated July 16, 1981 [Ref. 3j. The licensee's response was found not to be complete and a Request for Additional Information '(RAI) was issued by the NRC, dated January 6, 1982 [Ref. 4]. The licensee provioed a supplemental response in a letter dated February 12, 1982 [kef. Sj. This report provides a technical evaluation of the information provided in the licensee's responses to the Generic Letter, and includes a recommendation regarding the need for aoditional analysis and/or upgrading modifications of this plant's AFW system.

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e e EVALU.;TIQr~ Information provided in licensee's responses i~cluded: o Specification of the overall seismic capability of the AFW system. o Description of methoaologies and acceptance criteria for the AFW system, which is determined to be seismically qualified to the SSE level by the licensee. o Status of compliance with seismic related NRC Bulletins and Information Notices. o Schematic sketch of the AFW system. we have reviewea the licensee's reponses, and a point-to-point evaluation of licensee's responses against Generic Letter's requirements is provided below. (1) Seismic Capability of AFW System lne AFW system has been designed, constructed, ano maintainea to withstano an SSE utilizing methods and acceptance criteria consistent with

• • that applicable to other safety-grade systems in the plant. All areas of the AFW system (i.e., pumps/motors, piping, valves/actuators, po"er supplies, water source, instrumentation and control systems, and structures housing and supporting the AFW system) are seismically qualified to the SSE level.

The licensee provided a description -0f the methodologies and acceptance criteria used for seismic qualificaton of the AFW system by referring to the applicable sections of the FSAR. The description includes seismic analysis methods, seismic input, load combinations, allowable stresses, qualification testing, and engineering evaluations performed

• A switchover procedure to a secondary water source is not involved because the primary water source and supply path**ts seismically qualified
• Information regarding the seismic capability of any alternate aefay hea~ removal system is not required because the AFW ~ystem is fully seismically qualified. **-:... -;,,*-,--*,-.

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,. ~ d ~ 1 ~ ,':::,.',. *.:_.:_**:..,.:,.. *.. / '.. ;*.**..,....,:_:.. :.:~.. *;\\*.:..._~ ~*.,. -~.,:.~*****y Regarding the AFW~stem boundary, the 1;censee's ~onses ~id~not prov,ae sufficient information. Therefore, it is not clear that the licensee's AFw system bounaary fully meets the boundary requirements specified in Generic Letter 81-14. The licensee stated that the AFW system was included within the scope of seismic-related Bulletins 79-02, 79~04, 79-07, 79-14, 80-11, ano IE lnformation Notice 80-21. It is noted that documentation of the reanalyses of the Seismic Class I piping within the Scope of IE 79-14 was being completea, and the final reports were scheduleo to be prepared by

• Nov~mber 1981.

(2) walk-Down of Non-Seismically Qualified Portions of AFW Systsem A walk-down is not required because no lack of seismic qualification of the AF~ system is indicated. (3) Additional Information The licensee provided a schematic sketch of the AfW system including the ~ater source, heat sink, suction and discharge piping, major mechanical equipment, and structures housing and supporting AFW system i terns *

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• 3/ CONCLUSIONS The licensee's responses provided all the information that was explicitly requested by GL 81-14.

Based on this information, *we conclude that the AFW systems at Surry Units 1 and 2 wi_ll be able to provide the safety-related function following an SSE to assure safe shutdown of the plant. Therefore, we recormiend that no further action be*i~itiated regarding upgrading of the AFW systems of these plants under NRC Multiplant Action C-14. : -.,*:.... ~...* -*, *:.. !*--**::*.. --. -... ~* *;** -*:*::

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1.

O. G. Eisenhut, U.S. Nuclear Regulatory Commission, memorandum to H. R. Denton, "Multiple Action Plant C-14: Seismic Qualification of Auxi1iary Feedwater Systems, 11 February 20. 1981.

2.

U.S. Nuclear Regulatory Cormiission, Generic Letter No. 81-14 to all operating pressurizea water reactor licensees, 11Seis~ic Qualification of Auxiliary Feedwater Systems, 11 February 10, 1981.

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R. H. Leasburg, Virginia Electric and Power Company (VEPCU) letter to H. R. Denton of U.S. Nuclear Regulatory Commission, "Seismic Qualification of Auxiliary Feedwater Systems, Surry Power Station Units 1 and 2," July

1 16, 1981.

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S. Varga, U.S. Nuclear Regulatory Commission letter to R.H. Leasburg, VEPCO, "Request for Additional Information on Seismic Qualification of the Auxiliary Feed\\>,ater System, Surry Nuclear Plant Units 1 and 2, 11 January 6, 1982.

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R. H. Leasburg, Virginia Electric and Power Company, letter to H. R. Denton of U.S. Nuclear Regulatory Commission, 11Auxi1iary Feedwater System Seismic Qualification, Surry Power Station Units l and 2, 11 February 12, 1982 *.,.* -~ i,. ' r: ~ *.. : '. -...,.... ~.,. -.. r....... ~.... ~.,...,.......,.-.,-**.-. ..}}