ML20136J352

Further Response to FOIA Request for Documents Re Restart of Facility.Forwards Documents Listed on App H.Documents Also Placed in Pdr.Documents Listed on Apps I & J Withheld (Ref FOIA Exemption 5)

ML20136J352
Person / Time
Site:	San Onofre
Issue date:	08/07/1985
From:	Felton J NRC OFFICE OF ADMINISTRATION (ADM)
To:	Bell N NUCLEAR INFORMATION & RESOURCE SERVICE
References
FOIA-84-885 NUDOCS 8508200691
Download: ML20136J352 (5)

Text

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pm fo,, UNITED STATES

[ ) g NUCLEAR REGULATORY COMMISSION L 'p WASHINGTON, D. C. 20555

's, p AUG 't MS Ms. Nina Bell, Assistant Director Nuclear Information and Resource Service 1346 Connecticut Avenue, NW, 4th Floor IN RESPONSE REFER Washington, DC 20036 TO F0IA-84-885

Dear Ms. Bell:

This is in further response to your letter dated November 28, 1984, in which you requested, pursuant to the Freedom of Information Act (F0IA),

documents related to the restart of the San Onofre Nuclear Generating Station, Unit 1.

The documents identified on enclosed Appendix H are being placed in the NRC Public Document Room (PDR) located at 1717 H Street, NW, Washington, DC 20555, in file folder F01A-84-885 in your name.

The documents identified on enclosed Appendices I and J are being withheld.

The documents identified on Appendix I contain the predecisional analyses, opinions and recommendations of the staff on the restart of San Onofre, Unit 1.

The documents identified on Appendix J contain the predecisional analyses, opinions and recommendations of the Commissioners, and between the Comissioners and their staffs, on issues in the San Onofre restart proceedings. Because the documents reflect the predecisional process among the staff, the Commissioners, and between the Commissioners and their staffs, the documents are exempt from mandatory disclosure pursuant to Exemption 5 of the F0IA, 5 U.S.C. 5552 (b)(5), and the Commission's regulations, 10 CFR 59.5(a)(5). Release of the documents would tend to inhibit the open and frank exchange of iheas essential to the deliberative process. The documents on these appendices do not contain any reasonably segregable factual portions and are being withheld in their entirety.

Pursuant to 10 CFR 9.15 of the Comission's regulations, it has been determined that the information withheld is exempt from production or disclosure and that its production or disclosure is contrary to the public interest. The person responsible for the denial of the documents on Appendix I is Guy H. Cunningham, III, Executive Legal Director. The person responsible for the denial of the documents on Appendix J is John C. Hoyle, Assistant Secretary of the Commission.

This denial may be appealed to the Secretary of the Commission within 30 days from the receipt of this letter. Any such appeal must be in writing, addressed to the Secretary of the Comission, U.S. Nuclear Regulatory Comission, Washington, DC 20555, and should clearly state on the envelope and in the letter that it is an " Appeal from an Initial F0IA Decision."

B508200691 850807 PDR FOIA BELL 84-885 PDR

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2-The search for and review of documents that are subject to your request 1 are continuing. We will notify you when the search and review are completed, j i

Sin rely, '

M. elton, Director Division of Rules and Records Office of Administration

Enclosures:

As stated

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Re: F01A-84-885 APPENDIX H Documents Being Placed in the PDR

1. 11/20/84 Letter from Bell to Commission, re: Restart of San Onofre 1.

(2 pages)

2. 11/16/84 Handwritten notes of D. Humenansky on copy of 11/16/84 letter from Hodel to Palladino. (1 page) [The letter was released in our 7/8/85 response regarding this request]

3. 09/13/84 Handwritten notes of D. Humenansky on copy of SECY-84-360, Restart of San Onofre Nuclear Generating Station, Unit 1.

(5 pages) [The SECY paper was released in our 2/13/85 response regarding this request]

4. Undated Seismic Capacity of Piping Systens Based on Experience.

(6 pages) l

5. Undated Deterministic Justification for San Onofre Unit 1 Restart.

(3 pages)

6. Undated San Onofre Unit 1 Accident Mitigation Systems. (1 page) ,

7. Undated Summary of Probabilistic Analyses Supporting San Onofre Unit 1 Return to Service. (4 pages)

8. Undated Handwritten notes of D. Humenansky. (3 pages)

9. Undated San Onofre Nuclear Generating Station Unit I History. (2 pages)

n. ,

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Re: F01A-84-885 APPENDIX I DOCUMENTS BEING WITHHELD 1, 10/05/84 Note from S. Burns to G. Cunningham, subject: Miller and Chevalier Memo on San Onofre Restart. (3 pages)

2. 08/17/84 Note from J. Lieberman to F. Miraglia, subject: San Onofre Memo. (18 pages)

3. 08/10/84 Note from J. Lieberman to F. Miraglia, subject: San Onofre Commission Paper. (9 pages) 4 07/13/82 Note from S. Burns to W. Paulson, subject: Comments on Draft San Onofre Order. (1 page)

5. Undated Draft Commission paper, subject: Restart of San Onofre Nuclear Generating Station Unit 1. (10 pages)

6. Undated Handwritten notes of ELD attorney. (2 pages)

7. Undated Handwritten notes of ELD attorney. (1 page)

)

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8. Undated Briefing on San Onofre, Unit 1. (3 pages)  ;

9. Undated Draft letter from Eisenhut to Baskin, attachin Contingent Recission of Suspension. (6 pages) g draft order

10. Undated Draft letter from Eisenhut to Baskin, attaching draft order -

Partial Recission of Suspension.

11. Undated Draft Commission paper - San Onofre Unit 1 Restart. (2 pages)

Re: F01A-84-885 APPENDIX J DOCUMENTS BEING WITHHELD

1. 12/11/84 Unsigned Version Z (Cleaned-up version) (SECY-84-434)

(With Chairman's addition of 12/14 with slight modification, responding to J. K. Asselstine's views). (2pages)

2. 11/16/84 Memo from S.J. Chilk to Cmrs. , " San Onofre Unit 1," with handwritten notes of D. Humenansky. (1 page)

3. 11/14/84 Draft staff requirements memorandum. " San Onofre 1." (2 pages)

4. Undated Brief Sheets by D. Humenansky. (5 pages)

5. Undated Technical notes of D. Humenansky for L. Zech. (18 pages)

6. Undated Unsigned Addendum to Version Z SECY-84-434. (1 page)

7. Undated Handwritten notes of D. Humenansky on 11/8/84 meno from F.

Bernthal to N.J. Palladino, "COMNP-84-45--Decision Regarding Restart of San Onofre Nuclear Generating Plant, Unit 1."

(2 pages)

8. Undated Handwritten notes of D. Humenansky on 11/7/84 memo from T.M.

Roberts to Cmrs., " Proposal for Restart of San Onofre 1."

(2pages) .

9. Undated Handwritten notes of D. Humenansky on 11/17/84 memo from N.J.

Palladino to Cmrs., " San Onofre Unit 1 Restart." (1 page)

10. Undated Interoffice Questions /Coments for 11/21/84 meeting on San Onofre 1 full power license. (Commissioner Bernthal's office.)

(4 pages)

f a- O '

$ ;I THE SECRETARY OF ENERGY WASHINGTON. O C. 20535 7

- + November 16, 1984 l . . ..

Honorable Nunzio J. Palladino Chairman Nuclear Regulatory Commission Washington, D.C. 20555

Dear Chairman Palladino:

h Recently I was advised that you are considering a matter that has

[ [#4d# arisen in connection with the San Onofre nuclear facility that/ ma A N uodifications.%The question concerns whether an NRC "confirma-tory order" that is issued when a utility voluntarily undertakes safety modifications should be treated as a suspension order or an amendment to a license.

It is my understanding that if a confirmatory order that subse-quently is changed is considered to be an amendment to a license, more hearings would be held than would have been the case had a suspension order been issued. That appears to be both an' inequitable and inconsistent result becauseduM.-Tit'iesNhicFa&

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%vsiIcnMaxi)&1nay be exposed result of the additional hearings.to significant expense and delay as ,4e JEvthatX4ileggmaldi'scodraifes stigie,sgisr_gnExplugtgiMKundertakingisafety;3od,ific,atiog, I am sure you would agree that it would have serious public poFicy repercussions. 7 Therefore, I urge your most careful review of this matter. <4 c.c.urd Should you conclude that the public poliev concerns are of g ^'M C6 sufficient weight to favor treating confirmatorv orders as ~

suspension orders, I am confident after discussing the matter how w[3, with my General Counsel that a court would find such a rationale s u 0,3 persuasive and uphold your interpretation. f* wea ro If I may be of any assistance to you on this matter, please leta d'* *$

me know. pro b . d

% d i d,.rr vs Sincer.ly, & 44 To ruol"#-

Th+T eob ,

• p e nbig d4 M l DONALD PAUL HODEL SEN"' l Ague; - 3 1

11/16...To 0GC to Prepare Response for Signature of Chairman l and Comm Review...Date due: Nov 28...Cpys to: RF, Cmrs, EDO  !

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Seotember 13, 1984 POLICY ISSUE SECY-84-360 q

%.. wr(Commission Meeting).o/5 .- . v . l* l

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For: [-L}Lff;sA r.

Thes'y <. kirib . t.Gt % iw .. n g.9 ( ,, j. . . .

Ccmissioners /[ t

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'x )u.oee. f.x . . . s. ./'. .. 3 From: William J. Dircks

/ Executive Director .for Operations U.k. Jr]C. 5 y> p.a a # %- .,....T u y. ~ .l.

Subject:

RESTART.0F SAN 0tiOFRE bCLEAR GEldRATIf!G STATION UNIT 1 L' s

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Purpose:

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.0a.Q IA ..g a To request the Comission to review the staff's proposed Idti 'h b procedural of SancourseOnofre Unit for 1.a decision to authorize restart c.a (ls u. &c.i Discussion: *y ip. TA On August 11, 1982, the Office of Nuclear Reactor Regulation issued the enclosed immediately effective order entitled f0rcreFConffredacR .icensee ComitmentisTn Seht "~;redtag'.' .thqt,.4Pfectec. . southern 'CaTTo7nW" Eiff!r6MGremlHmyttr.1*ir#_fhrama_n-tsrng'UC.lLFN.lilrritM" sh8kv Awvup w uu-1mtti- su.au9Esrtfescribedrin

[t'hEl i ce n'see istf ubmfitaEtied >Ju ne v is p.:1982 'a'sirsup -

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p],ementeTby';TeueCaift"etrVfme-i r, misos carepyleted anOllCTsipfWaI5fi1KiWegitot Reg. 36058,T057TAug.18', IWd2fT5nc rits}{iosure 1).fff47" TheFed'.

licensee has completed some, but not all, of the modifications required by the order. W.'daititdl acra..edf M ~ i4 Au' gust 3fET95TI-copy'affEFedFUiiirsTicehiss haf u . c. d ~.~ c.1.c rdqigtigfiqEl!OTEitglLTiteRTosu re 2). '

.M The August 1982 order confirmed the licensee's proposal to maintain plant shutdown until modifications it described in the referenced letters had .been completed.

ThF licensee made its comitments as a result of the i refr questions,regerjasagrgne:ilpTM 'Blegifuggrafely) .. ,

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CONTACTS:

E. McKenna (NRR)

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\ J. Lieberinan (ELD)

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The Comissioners - 2-As discussed in the licensee's Jur.e 15, 1982 letter, analyses to reconfirm that the plar.t met its original seismic design basis would cor.sure sig ificant resources and would not contribute to the overall coal of upgrading the plant to withstand a postulated O!679 q earthquake. Theref oi eMthel i cens eeNs' tea'd? est~abilsygg c.d E.ix ao 7mpiemenIation pian' ftir-~Ufgyt[d.iAg"a.1Lsa.fety reiated plant - featu res zin' thelune224w 1982; I ette r. ^ine Raff helrogram,establ Ts%fliy7 7ili licensee would agF.'eegtha}e}

resolvd th staff'sconcernsabouttheabilityoftheplant to safely shut dcwn following its original seismic design basis event (0.5g), because the plant would be upgraded to withstand the 0.679_ earthquake. Accordingly, the staff issued the " Order Confirming Licensee Commitment on Seismic Upgrading" to bind the licensee to its comitments to undertake the modifications to the plant.

From the staff's understanding of the modifications that the licensee has made to date,' TON,pjabTe"fF6fn3 5 -c.:d o

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r.ediffcati.;c.;.dn- r ------ ~y,Tle l icensee desir,es 'ariris requireo u resuae e.etcial operation of San Onorfy,mu.u.weverwarr r#mme-rsh-terms of an Tmier of the CalTforniaiPiiblfMfTitfRs?idifs]!pn pg i f YMM* td"be7etimed'irFtheTaTe"MFCf P1 ant criticality is targeted for the beginning~of November 1984 to support this objective. The licensee's representatives have indicated that, if restart is delayed, future

. operation of the plant may be jeopardized.

The staff is seeking the Commission's guidance on the appsepneteprecednywra.ww.vdroi16T16fXdeEs19n'.t3 ag*zettheMigitifwwmrcauseMMcenseeg~ g..

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==v-8e, acklege, he staff

- offers the following summary of its technicarposition with respect to the request to extend the completion date for the plant modifications. This position is tentative because the reviews have not been completed. -

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, 1 The Comissioners .

Revised Prceosal for Plant Restart In Deceder 1993, licensee submitted a ;:re1Hnary 1 proposal for returning San Onofre Unit 1 to operation l without undertaking all of the modifications described in the letters which ~were incorporated in the August 1982 order. That plan described the scope of planned structures and systems to be upgraded and evaluation

criteria for determining the scope of necessary modifi-cations to ensure safe shutdown capability before resuming operation. The basic premise of the plan is

• that modifications will be completed to ensure that all structures, systems and components whose failure could cause an accident and/or whose function is required to achieve and maintain a hot standby condition will be -

available following a 0.67g earthquake. The evaluation criteria were developed to demonstrate that required efuipment will survive the postulated earthquake and remain functional.

0,n February 8,1984, NRR issued a safety evaluation report on the proposed criteria for restart. This i(SER concluded that the plan and criteria, subject to ,

/ exceptions noted, would, when implemented, he

' sufficient to demonstrate the capability to achieve a

'~.. hot standby condition for a postulated safe shutdown ehrthquake such that the staff would conclude plant

- restart should be allowed prior to the complete resolution of all SEP seismic issues for Unit 1. This' evaluation concluded that the remaining scope of the seismic reevaluation program should be addressed for long-term resolution and that all seismic issues should be substantially resolved prior to restart from the fext refueling outage.

The scope of structures, systems and components for pro-posed plant restart includes sa.fety-related structures (buildings), the reactor coolant pressure boundary, main steam and main feedwater piping, auxiliary feedwater system and the reactor coolant makeup charging system. The scope l

also includes supporting equipment needed to operate the above systems. Upgrading of the major piping systems

. ~ , , provides reasonable assurance that an accident will not be induced as a result of an 0.679 earthquake. The

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'other systems provide a means for decay heat removal Q .". such that a hot standby condition can be maintained.

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The Conaissioners .

.The above measures, therefore, would minimize the potential for an earthquake to initiate an accic'ent and wculd prcvide a means 'cr reaching :nd maintai -

ing a safe shutdcwn condition following a postulatec 0.679 earthquake. The remaining systems and com-ponents encompassed by the initial scope of the seismic reevaluation program are those which would nonnally be used to reach cold shutdown (such as residual heat removal system and supporting systems) and those used for accident r_niti S ation (such as safety N injection). As discussed above, the piant will have

- the capability to reach and maintain a hot standby condition for several days. At that time, other t sources of water could be cbtained for longer term

- cooling. Therefore, for an interim period until the

>l seismic reevaluation program 'is complete, the proposed scope of plant upgrading will provide reasonable assurance that safe shutdown can be attained such.

that operation of San Onofre Unit 1 would not pose an undue risk to public health and safety.

The modifications to mechanical equipment and piping in accident mitigating systems have not all been completed.

However, as discussed above, the. reactor coolant pressure boundary and large steam and feedwater piping have been f upgraded to withstand the 0.679 earthquake. Therefore, f

. .the staff believes that the risk of a seismically- 1 i induced large accident which would require use of the accident mitigating systems would be sufficiently low

. , until a technical evaluation could be completed to identify all needed plant modifications for the remainder of plant 3

- life. The licensee has proposed to cont'nu.e reevaluation

- i of these remaining systems and components and provide the l results by the end of the present core cy'cle. The implementation schedule for any identified modificaticns would then be defined by the relative safety significance

- of the needed modifications. $taff review of the appro-priate schedule for long-term seismic resolution is continuing. -

Legal Aspects of Authorizing Restart The appropriate procedural path for a decision to authorize

,, restart depends on which of two views of the August 1982 order is taken. One reading of the order is that the order modified the San Onofre Unit 1 licens'e to inccrporate J

conditions on operation which could only be. altered or re-moved by further amendment of the license. Alternatively ,

i the order might be viewed as primarily a suspension order p.

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The Commissioners until certain acticns were taken and, though the ceder limits operation of the plant, the order did not " modify" the license. Under this latter theory, restart coulo be authorizeo by merely lif ting the suspension imposed by the August 1982 order.

The order itself is not labeled a " suspension" or a

" modification" order, but it clearly has . elements of both types'of orders. Like other confirmatory orders, this order was intended to bind the licensee to its comitments - here, the c;tnittents to undertake plant modifications and to extend the then existing plant outage until those modifications were made. If,

> If authorizing restart is viewed in the can' text of an application to amend the San Onofre operating license, the pivotal issue, in terms of when restart authority could be given, is whether a "no significant hazards consideration" finding can be made. 10 C.F.R. 55 50.91, 50.92. If ,

such finding could be made, the amendment could be made effective upon issuance; if the finding could not be made, effectiveness would be delayed until after the

~

thirty-day period in which a hearing may be requested or, if a hearing is requested and granted, until af ter completion of the hearing process.

The difficulty associated with making this finding

. becomes apparent when one looks to the relevant base-

,line for assessing the relevant factors set forth in i 10 C.F.R. 5 50.92(c). If the August 1982 order is viewed as having the effect of amend.ing the license

. by requiring modifications to the plant, the license as it now exists (which includes the provisions of tfie order) requires that, prior to restart, all com-

.. mitments made by the licensee in its letters of June 15 and 24, 1982, be completed. At present, not all of the commitments have been met. Thus, the restart at this time would entail a relaxation of the terms of the license or, stated in terms of the

."significant hazards consideratTon" criteria, a '

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reduction in a margin of safety. Consequently, the

• no significant hazards consideration" finding could if Unlike more recent enforcement orders, the August 1982 order does not provide expressly for a relaxation of the terms of the order.

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SEISMIC CAPACITY OF PIPING SYSTEMS BASED ON EXPERIENCE

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4 I. INTRODUCTION Structures, systems and components have substantial reserve capacity with respect to their earthquake withstand capability. In the case of piping this is demonstrated by ri,sk assessments, test results, and actual earthquake experience. In general, piping can be shown to be relatively rugged with respect to its seismic capability.

M '

m h contribution of piping systems to the overall coremelt frequency in  ;

probabilistic sk assessments, g the results of dynamic testing of  ;

piping and xperience of piprng systems in actual egarthquakes.

II. PROBABILISTIC RISK ASSESSMENTS Published probabilistic risk assessments (PRA) done at other nuclear plants were reviewed to identify the dominant contributors to seismic core melt frequency. This review was documented in Reference 1. The first step in this evaluation was a review of three published PRA's (Zion, Indian Point Units 2 and 3, and Limerick) to attempt to characterize the dominant contributors. The list of dominant contributors to core melt was supplemented based on discussions with PRA experts as well as to include seismically induced failures which are major contributors to offsite consequences.

Based on this review of existing seismic PRA studies, the dominant contributors which were identified were broadly categorized as (1) ons.ite power, (2) essential wa ter supplies, (3) structures and L4) reactor i con 1 "+ m +== was ,IudedQIiat} uraTfWctj{e" f fai FaTSIh E3 En Y,f aQ~domij Q 1on'

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ypes of piping systems that w d Pp$ @nTin i contributors were non-ductile pipe, threaded joints and piping routed between structures. These special circumstances are discussed below with respect to the design of SONGS 1.

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Histor'ca expertence nas snown tnat such systems have a very high '

- seismic withstand capability. This experience is reflected in seismic PRA fragility data, all of which indicate that the median ground acceleration capacities of welded ductile steel piping systems are sufficiently high that - even considering uncertainties - the probability of failure at ground accelerations of 0.67g and lower is small and not a major contributor to seismic core melt frequency even for piping systems which were designed for a Safe Shutdown Earthquake much lower than 0.67g.

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Ga,r ta a.19Adgwrunsure the saf e ig te m) slutuuwe

- 10%4#th capab) ity of SONGS 1, an alternate means of heat removal has

/@y- beenhas provided for systems been eliminated as arequired potentialfor safe shutdown.

contributor Thus, to seismic corethis meltitem

( #f, frequency.

SONGS 1 utilizes no threaded joints in process piping for essential systems. Therefore, this item is eliminated as a potential contributor to seismic core melt frequency.

SONGS 1 contains some essential piping spanning buildings on separate foundations. The evaluation of piping spans between structures that are required to attain safe shutdown has been specifically addressed. Thus this item has been eliminated as an important contributor to seismically induced core melt frequency.

~

Based on this review of seismic PRA's it is concluded that piping is not

'. a major contributor to seismic risk. Even the special circumstances of potential problem areas have been eliminated at SONGS 1.

III. 0YNAMIC TESTING OF PIPING Researchers at UCLA undertook a program to dynamically test nuclear related piping and equipment in the late 1960's at San Onofre. These tests were performed with small shakers on the operating deck of the reactor building and were very low amplitude. Though these tests demonstrated the capability of piping under. dynamic loads, the nature'of l the tests and the state of the art at the time are a limitation on the usefulness of the results.

- 1 Recently,adiii p- enaeu av sinVjgTJiYeTe7 i I-- 's Wenis T IMe Deen underh te h i N org, RIdM .

TIG~e7 G D WdTog ent M ,7 I

,@$cM JJi}g6eer^1pMesea(_c a__3Q QeW'

- inere are"TidfTErTtles intl he results 5 summarized as follows:

p piping systems have withstand capabilities well beyond the limits of I the design amping in piping systems tends to be higher than used in current design practice l lexible piping systems have substantial withstand capability that is not predicted by linear analysis and even exceeds that predicted by nonlinear analysis.

A sununary of some recent piping tests is described in the following e paragraphs.

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A. Small Bore Piping ANCO Engineers has performed a number of small bore piping tests for Kraftwork Union (KWU) in the Federal Republic of Germany, EPRI, and

! the Bechtel Power Corporation. Of particular interest are the tests performed by ANCO to qualify small bore piping for KWU, (References 2 and 3). These tests were used to generically qualify flexible small bore piping without the need tn perform sophisticated compute.

. analyses. The qualification of existing small bore piping in KWU nuclear power plants to withstand low frequency loading (SSE) and high frequency loading (aircraft impact) was successfully demonstrated by ANCO Engineers for KWU.

I A series of full-scale tests, using small bore piping systems typical of those installed in KWU nuclear power plants, was conducted on a shake table. Nine small piping configurations were selected for testing. These configurations are representative of the large majority of piping systems in nuclear pcwer plants and are the most critical sections for each type. Trapeze-supported, hung, and horizontally restrained systems were included in the test program. A variety of boundary conditions, such as one-dimensional restraints, hangers, stops, pressure ranges, and added masses, were also investigated.

These tests clearly showed that small bore piping is capable of

( surviving low and high frequency loads where large displacements, accelerations and even plastic strains occurred. Some accelerations were in excess of 50g, displacments were in excess of 50cm and plastic strains were in excess of about 0.6%. The tested piping configurations survived without collapse, leaks or loss of pressure. Stress anlayses performed on these lines indicate large overstresses, as much as 300 to 400% over the code allowable stress levels.

B. Large Bore Piping ANCO Engineers has also performed a number of tests of large bore piping systems. These tests were performed to obtain benchmark data

, for piping computer codes and to demonstrate piping design margins for dynamic loads.

In one test program (Reference 4), two 20 feet runs of 4-1/2 inch carbon steel piping were tested. High level dynamic loads above the elastic range of the piping material and above the Code Class 2 Level 0 stress limit were induced in the piping system with peak input accelerations ranging above 10g. The piping systems successfully withstood repeated dynamic loading at input levels from three to four times greater than those necessary to exceed the ASME Class 2 Level D stress limit for primary loads.

. . . . . . . _ . _ _ ==

In another test program (Reference 5), two configurations were tested. One piping system was a single run of carbon steel about 70 y feet long comprised of six inch and eight inch schedule 40 piping. ]

The second system consisted of two 3 inch schedule 40 branch lines tied into a mainline similar to that in the first test. The tests -

included time histroy input with a peak acceleration of 8.4g. The test inputs were a factor of 4 greater than that necessary to match the Level 0 stress limits. The piping system withstood these severe dynamic tests with no gross distortion or loss of pressure retaining capacity.

m IV. EARTHOUAKE EXPERIENCE  ;

A formidable quantity of contemporary evidence is available to demonstrate that piping systems and equipment designed with controlled flexibility have the capacity to withstand forces far in excess of those for which they were designed.

morethantwentypowerplants/a'Ieference6includesdatacoll;ctedfrom nd industrial facilities which were subject to severe seismic motion. A typical example is the ESSO refinery in Managua, Nicaragua which was designed to meet provisions of the Uniform Building Code for a 0.29 seismic acceleration. During the 19i?

Managua, Nicaragua earthquake, the peak acceleraton measured at the a refinery was 0.39g E-W and 0.34g N-S. Despite the fact the ground acceleration exceeded by nearly 100% the acceleration for which the systems were designed, virtually no damage was sustained by the piping

('

systems and equipment. The plant was shut down for inspection but was operating at full capacity within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Even more impressive evidence can be found at the ENALUF Power Plant which was subject to an estimated 0.6g ground motion during the same earthquake. This plant

~

sustained no damage to its piping and equipment, despite a probably non-existent seismic design.

In addition to the su.vey presented in Reference 6, a more comprehensive a study was made of the response of the El Centro steam plant to the 1979 "

Imperial Valley earthquake by Murray, et. a  ;

W WAUL &416652 erenge- '

same _ amont rata NAb 'j. N M

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. rTgnu1 cant conclusions of this study re a e o -

excerpted as follows:

(1) 'No high-temperture or high-pressure piping failed during the earthquake." -

k' (2) " General observations indicate that the piping systems are hung in a more flexible manner than that which would be required by current NRC criteria."

5 9

=

(3) "In most cases, the piping is supported in a similar manner to older operating nuclear power plants, and it may be inferred that the seismic response would be similar. These observations are, on the surface, encouraging since in all cases the circumstances leading to failure are dissimilar to nuclear applications in that damage occurred at weld repaired areas of past corrosive attack or at nonwelded pipe joints."

The evidence of earthquake experience clearly indicates that piping systems that are well laid out and anchored according to industry practice have an inherent resilience that permits them to withstand substantially greater seismic inputs than would be indicated by current design practice.

V. CONCLUSION Based on the information presented above it is concluded that piping failure is not a dominant contributor to seismic risk. Further, based on both testing and actual experience, piping can withstand dynamic loading several times its design level and several times the minimum acceptable ASME Code level.

VI. REFERENCES

, 1. Letter from M. O. Medford (SCE) to 0. M. Crutchfield (NRC), " Return

( to Service, Seismic Reevaluation Program, San Onofre Nuclear Generating Station, Unit 1," December 23, 1983.

2. Ibanez, P., Keowen, R. S., Rentz, P. E., " Experimental Study of Dynamic Behavior of Piping Systems Under Maximum Load Conditions--Testing," 1982 ASME Orlando Conference.

3. Sand, Lockau, Schoor, Haas, " Experimental Study of Dynamic Behavior of Piping Systems Under Maximum Load Conditions--Analysis," 1982 ASME Orlando Conference.

4. Howard, G.E., Johnson, B.A., Walton, W.B., " Piping Extreme Dynamic Response Studies," Nuclear Engineering and Design 77, pp 405-417, 1984.

5. ANCO Engineers, "Laboratary Studies: Dynamic Responses of Prototypical Piping Systems," NUREG/CR-3893, August 1984.

6. Cloud, R. L., " Seismic Performance of Piping in Past Earthquakes,"

Proceedings of the Specialty Conference on Civil Engineering and Nuclear Power, September 15-17, 1980.

7. Murray, Nelson, et. al., " Equipment Response at the El Centro Steam Plant during the October 15, 1979 Imperial Valley Earthquake," NUREG CR-1665, October 1980.

JLR:2629F

a_ __

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Detenainistic_ Jus tification or San Onofre Unit 1 Restart I. Introduction

• San Onofre Unit I was originally designed and constructed with the safety systems, those designated seismic category A, able to remain functional following a 0.59 seismic event. The Seismic Reevaluation Program has  !

since been structured to upgrade the plant to be able to safely withstand i a more severe 0.67g Housner earthquake. The emphasis of the Systematic Evaluation Program of which the Seismic Reevaluation Program has become a part, is to maximize the safety improvement of the plant.

Upon return to service from the current outage the plant will have substantial upgrades that will assure that it can safely shutdown following a 0.679 Housner earthquake. This document will delineate the basis for the current outage upgrades and will demonstrate the capability of the plant to safely shutdown following a 0.67g Housner earthquake.

II. plant Status for Restart  !

The emphasis of the Seismic Reevaluation Program has been on a phased upgrade of (1) the Reactor Coolant Pressure Boundary, (2) structures, and (3) remaining systems and components. The goal of the program has been to eliminate the possibility that a design basis type event would be caused by an earthquake of a magnitude even larger than the original plant design basis and that the plant would be able to safely shutdown following such an event. The modifications in the following table have been completed to achieve the program goal.

Table 1 Structures. Systems and Components Designed or Upgraded to Withstand a 0.674 Housner Seismic Event

/

Structures Containment Sphere Enclosure Building Diesel Generator Building Turbine Deck, North, West and East Platforms Control Building Seawall Masonry Walls in Ventilation Building, Reactor Auxiliary Building, Fuel Building and Turbine Building Fuel Storage Building Service Water Reservoir l

l l

l

- '- _g_

Systems and Components 1

I Reactor Coolant Pressure Boundary Standby Power System l

Auxiliary Feedwater System (Including New Tank)

Portions of Charging and Letdown Systems Necessary for Safe Shutdown Intertie Between Spent fuel Pool and Charging System Portions of the Main Feedwater System Necessary for System Integrity Portions of the Main Steam System Necessary for System Integrity and to Provide Steam Dump Capability.

In addition to the modifications listed, major improvements to other systems have been initiated, but will not be completed during the current outage.

III. Plant Response to Severe Seismic Event The modifications that have been completed are intended to satisfy the requirement to achieve safe shutdown following a severe seismic event.

en r-

-c.7 us ,--mm r a gam m g s,s,ureen en ~;a,sig frip r i e n

,mvan  ; e -

h < a n$ee ~ N u m uince the Emergency Core Cooling dystem .s requ, red only to flood the core under conditions of loss of f coolant or shrinkage due to rapid cooling, upgrades to the system are not t '

necessary.

Following a seismic event, reactor shutdown will be initiated manually (if not automatically caused by the event) and the reactor will be maintained safely in a Mode 3 or Mode 4 condition. The shutdown will be achieved using the charging pumps (the test pump and one normal charging pump with cooling supplied by its own fan) to provide makeup due to shrinkage and minor leakage from the Reactor Coolant System. The 6 Component Cooling Water System, which normally cools the charging pumps M p h ? will not be required due to the capability of the charging pump cooling g in f'# fan. The test pump does not require external cooling.

Makeup water for the charging system will be supplied by a new intertie to the spent fuel pool. This path will be made available following the event by action of an operator who will be dispatched to manually align the system. All other connections that might otherwise supply makeup to the charging pumps will be isolated. The spent fuel pool will be used as the makeup source and 80,000 gallons of borated water will be available which is sufficient makeup for at least I week assuming worst case conditions. Should additional borated water be required it can be l manually added directly to the spent fuel pool. J The reactor will be cooled through the use of the completely upgraded 1 Auxiliary Feedwater System through its connection to a new Auxiliary feedwater Storage Tank. The system is completely redundant. The steam generators will act as the heat exchangers for cooling the RCS through i

natural circulation with the steam being dumped through redundant steam

( dump valves. The requirement to remove heat from the Reactor Coolant l

(

l .

f System will be met by the Auxiliary feedwater System with water supplied

- by the new Auxiliary feedwater Storage Tank. With the minimum required 150,000 gallons in the tank there is at least 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> of cooling

. capability. With the maximum amount of water in the tank, over 240,000 gallons, there is at least 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> of cooling capability. Once this water source diminishes, additional supplies can be made available from the 3 million gallon service water reservoir. With this water the plant

. can be safely cooled for over an additional 21 days. In this period of 1 time an indefinte amount of cooling water can be made available from external sources.

IV. Conclusion With completion of the. current upgrade program, San Onofre Unit I will have tt.c capability to withstand a severe seismic event without the loss of reactor coolant system integrity and can be maintained indefinitely in a safe shutdown condition using only those systems upgraded for a 0.679 Hounser event.

V. Reference Letter, Walt Paulson, NRC, to R. Dietch, SCE, regarding SEP Topic VII-3, Systems Required for Safe Shutdown, dated November 12, 1982.

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(D SAN ONOFRE UNIT 1 ACCIDENT MITIGATION SYSTEMS MAX. SCOPE  % COMPLETE Pipe Supportsl 2700 40+

Raceways 2 1400 80+

Equipment Anchorage Likely no mods Required N2 Back-up Minor Not Started Structures Additional work may be required General Notes

1. Upgrades Assure no Accident due to 0.679 Housner Earthquake

2. Mitigation Systems Retain Original Capability and are Improved Due to Already Completed Modifications

, 3. Piping is not a Dominant Contributor to Risk

4. Plants of 0.lg or 0.2g have Withstood Estimated 0.5g

5. Improvement During Outage Estimated at 35 to 125 Times

6. Improvement from Completing Accident Mitigation Estimated at Less Than an additional 10%

Specific Notes 1 Containment spray inside containment is 100% complete 2 May need no further modifications

SUMMARY

Of PROBABit.ISTIC ANAL.YSES SUPPORTING SAN ONOFRE UNIT 1 RETURN TO SERVICE Introduction The risk associated with seismic events at San Onofre Unit 1 is dependent upon several contributors as follows:

Seismic Hazard - the probability of an earthquake, the associated magnitude, and the type of structure being affected.

Plant Design Criteria - The magnitude of earthquake selected as a basis for plant design.

Plant Seismic Capability - The actual capability of a plant to withstand a seismic event.

Relative System Importance - Each system contributes more or less risk according to its need for maintaining the reactor in a safe condition.

Each of these areas have been reviewed and estimates have been placed on the magnitude of the risk associated witih seismic events for San Onofre Unit 1.

Seismic Hazard f

i The seismic hazard for San Onofre Unit I has been estimated based on measurements and analysis applied to local faults (References 1, 2, and Attachment 1 to Reference 3).

> " '-- - 1_ _ _ ;_ - mm. mm mom.,n.. ;,ty?smEdp e (References 4 through 15).

l- The result of the studies is that the Instrumental Peak Ground Acceleration (IPGA) for the San Onofre Unit 1 site is as follows:

Ground Acceleration Corresponding Return Period gn M M 1.5 x 104 years W -

)D M 4 x 105 - 1.5 x 106 years i

These low numbers in themselves, especially considering the conservatisms used in their calculation, demonstrate the low probability of an event that could challenge the plant seismic capability.

Plant Design Criteria The original San Onofre Unit I design was intended to assure the function of safety systems for a 0.5g seismic event. The current upgrade program will assure the function of equipment for a safe shutdown of the plant following a 0.67g Housner event.

2 Plant Seismic Capability Notwithstanding the criteria used in the design of the plant, experience at industrial facilities similar to San Onofre Unit I has clearly demonstrated that plants designed for a particular level of earthquake can withstand events of much greater magnitude (See References 16 through 23). As described in SCE's December 23, 1983 submittal, and described in detail in Reference 21, recent experience at a generating facility demonstrates a safety margin of at least two. (The El Centro Steam Plant in the Imperial Valley of Southern California experienced an earthquake in 1979 estimated to have caused ground acceleration of approximately 0.5g. Though the plant was probabily designed i for a ground acceleration of between 0.lg and 0.2g, it experienced no damage to high pressure or high temperature piping.)

Relative System Importance b'seMstem(/r ,. risatutai'n}cths 0Y f f k._ _k, " .hh. ,thyeaEtoiECs6Mit,DQ'is

. ,,m . . . _

-- -- susw n . DiTs -

supported by a review of the dominant contributors to seismic risk identified through Probabilistic Risk Assessments performed at other nuclear facilities as described in Appendix B to Reference 3. At San Onofre Unit I all those dominant contributors will have upgrades completed prior to return-to-service from the current outage. The primary remaining items are on systems that do

/ not significantly contribute to the risk and are associated with those

\

portions (primarily piping) of these systems that have been identified as being resistant to seismic loads far in excess of design.

Results of Risk St'udies In order to combine the offects of each of the above areas, a limited PRA a

study has been done for San Onofre Unit I and was included as Appendix C to Reference 3. The study constructed fault trees specific to San Onofre Unit 1 .

and applied data from other PRA's and the Seismic Safety Margin Review Program

, (SSMRP). Tyy "" ' gm e--_ _-- mf,y.gw v3mripymworgne ge

,,{,,...,...,,, .,2. W q r '

aY This number ret lects that the plant has been

, p _ ,, ""! s gn cn I at the upgrades have been concentrated on those w.. l-systems most important to seismic risk. This number is well within the NRC 1

- 2 7 Safety Goal for large-scale core melt of less than 10-4/ year.

s....w~_~

...w~ Since any estimate of the seismic risk is subject to uncertainty, and because the emphasis of the Systematic Evaluation Program is to maximize relative plar " imoroven" 2 F" har C udy ' Reference 24) has been performed. D17 r 2=2 - ; '

cla;F y nsmIgevenmat.isan$of'rV TI)i Na h "I 112EthdteggggAteg a m notea t1at because of the re

$ 16begi10J M ofdha;rarrant entageJ It was ative unimportance of the systems which have not been completely upgraded and because of the low contribution to risk of those portions of those systems which have not been upgraded (piping), the further improvement due to their upgrade would be less than 10%.

@q - , , - - -

,, p, m ,, - - - - -

^*

I Conclusion i

l The seismic risk at San Onofre Unit I has been evaluated and quantified to be  !

approximately 2 x 10-5/ year which is comparable to that at other nuclear j facilities. The relative improvement in plant safety due to the modifications l performed during the current outage is on the order of 35 to 125 times.

Further improvements would not sigificantly improve these numbers.

l References '

l. Wight, L. H., " Evaluation of Peak Horizontal Ground Acceleration Associated with the Offshore Zone of Deformation at San Onofre Nuclear Generating Station," TERA Corp., Exhibit No. LHW-1, Direct Testimony, ASLB Hearings, 1981, report dated August 1980.

2. Campbell, K. W., "Near-source Attenuation of Peak Horizontal Acceleration," BSSA, v711, pp. 2039-2070, 1981

3. Letter, M. O. Medford, SCE, to D. M. Crutchfield, NRC, dated December 23, 1983

4. Boore, D. M., "The Effect of Simple Topography on Seismic Waves:

Implications for the Accelerations Recorded at Pacoima Dam, San Fernando Valley, California," BSSA, v63, pp.1603-1609,1973.

5. McNeill, R. L., "Some Possible Errors in Recorded Free-Field Ground Motions," Draft internal memorandum for Sandia National Laboratories, Albuquerque, 1981

6. Bycroft, G. N., " Forced Vibrations of a Rigid Circular Plate on a Semi-Infinite Elastic Half Space and on an Elastic Stratum," Phil. Trans, Roy. Soc. London, 1956

7. Bycroft, G. N., "The Magnificantion Caused by Partial Resonance of the Foundations of a Ground Vibr'ation Detector," Trans. AGU, v38, 1957

. 8. Bycroft, G. N., "The Effect of Soil Structure Interaction on seismometer Readings," BSSA, v68, 1978

9. Pasecnik, P3 " Theoretical and Experimental Study of the Resonance of a Seismometer System (in Russian)," Izv. Akad. Nauk SSSR. ser. geofiz.,1952 l 10. Wolf, A., "The Equation of Motion of a Geophone on the Surface of an Elastic Earth,' Geophysics, v!X, 1944

11. Washburn, H., and H. Wiley, "The Effect of the Placement of a Seismometer on its Response Characteristics," Geophysics, vVI,1941

12. Safar, M. H., "On the Minimization of the Distortion Caused by Geophone-Ground Coupling," Geophysical Prospecting, v26, 1978 l

l l

l

13. Fail, J. P., G. Frau, and M. LaVergne, " Couping of Seismographs to Soil )

(in French)," Geophysical Prospecting, vX, 1962 1

14. McNeill, R. L., " Machine Foundations: The. State of the Art," Invited Paper, Proc., Spec. Session 2, Seventh Intl. Conf. on Soil Mech. and Fndtn. Engrg., Mexico City, 1969

15. McJunkin, R. O., " Strong-Motion Free-field Site Design Characteristics,"

California Geology, Aug. 1979

16. Real, C. R., McJunkin, R. D. and E. Leivas, " Effects of Imperial Valley

- Earthquake," California Geoglogy, Dec. 1979

17. South Carolina Electric and Gas Company: " Seismic Confirmatory Program for Equipment and Components for the Virgil C. Summer Nuclear Station (with Addenda)," Docket No. 50/395, OL NPF-12, License Condition 2.C(25),

March 9, 1983

18. Conference Proceedings, EERI, "Managua, Nicaragua Earthquake of December 23, 1972," 1973

19. Reconnaissance Report, EERI, "Managua, Nicaragua Earthquake of December 23, 1972," 1973

[ t

20. Steinbrugge, K. V., " Earthquakes, Volcanoes, and Tsunamis," Skandia America Group, NY, 1982

21. Murray, R. C., Nelson, T. A. Campbell, R. D. Young, J. A., Levin, H. A.,

Martore, J. A., and L. Reiter, " Equipment Response at the El Centro Steam Plant during the October 15, 1979 Imperial Valley Earthquake,"

NUREG/CR-1665, 1980

22. Yanev, P. I., Hou, S., Swan, S. W., Chan, T. K., and P. Ouborg, " Survey of the Effects of the May 2, 1983 Coalinga Earthquake on Industrial facilities," Draft report expected to be updated and issued in the near future, 1983

23. EQE, Inc., " Analysis of failed transformer anchorage in Coalinga," letter report to R. L. McNeill, 1983

24. Guey, C. N., Hughes, E. A., and Lambert, H. E., " Evaluation of the Core Damage Risk Reduction Associated with Seismic Modifications at the San Onofre Nuclear Generating Station, Unit 1," submitted via letter from M. O. Medford, SCE, to 0. M. Crutchfield, NRC, dated July 30, 1984 GEH:2623F

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o San Or.cfre Nucicar Generat're Station (SONGS) Unit i History '

1967 - Several systems ("irportant to safety" ard safety-related) were designed to .59 1973 - 1. Unit 2 and 3 designed to a seismic basis of .679.

2. SCE, on own initiative, starteo upgrading and reevaluating Unit l's seismic design.

3. SCE actually completed structural modications.

1978 - Staff started the Systematic Evaluation Program (SEP). One of those issues concerned seismic oualification checks on balance of plant structures and piping and mechanical equipment needed for shu+down and mitigation.

1979-1981 - 1. SCE worked with staff on SEP and defined scope of SEP as well as agreed to upgrace sone structures, such as the turbire building extension and feedwater heater platform.

2. 1560 petitions filed to ask SONGS Unit 1 to shut down based on seismic concerns.

3. Staff denied petitions, stating, " Continued cperation was satisfactory since original design of .5g was met and plant was upgrading."

1982 - 1. SCE found, using new seismic techniques, that some equipment piping in their supports had calculated high stress areas.

- Enough of an uncertainty existed to place doubt in the original .5g design basis as being met.

2. Since SCE could not find documentation, they agreed to upgrading the whole to .679 in a June 15 and subsequent June 24 letter. They agreed to extend their outage until the proper modifications were done. They originally shut down for some steam generator rework. (Promised a Cadillac when a Ford would do.)

3. In August, the staff issued a confirmatory crder to keep plant shut down until the seismic upgrades were accomplished. This order said to stay shut down until mods described in the June 15 and 24 letters were completed.

4. Staff and SCE cannot agree on criteria to use, so SCE diverted their attention to Units 2 and 3, while they mothballed Unit 1. Staff changed criteria requests about 4 times which caused more and more delay.

Dec.

1983 - SCE stated it was not economically practical to do all the l modifications prior to startup. They wanted relief to upgrade only the reactor coolant system, the main feed and main steam systems, to ensure that they would withstand a .67g Safe Shutdown Earthquake (SSE) and therefore, keep the core covered. They would complete y upgrading accident mitigation systems (ECCS) within two refueling outages. Currently, it is not known what seismic basis the ECCS systems are designed and built to.

1

[f _i J

, Feb.

1984 - Staff wrote tc. SCE stating SC. N GS Unit ' is technically okay te startup and run on an interim basis because the plant cculd achiave a het shutdown status inde'initely. Acc1 cent mitig? tion systems would be studied anc modified by the second refueling outage. These items nad tc be, and have been incorporeted inte the integrcted living schedule.

tiay 1984 - SCE reports to their Public Utility Ccmmission to place and keep Unit 1 in the rate base, because of the February letter and verbal communications with the staff. They had ccnfidence through that letter and verbal corrunication that the NRC would not be the critical path item to obtaining cerrericial operations by January 1985.

9 E

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