ML20023A456
| ML20023A456 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/02/1982 |
| From: | Harold Denton Office of Nuclear Reactor Regulation |
| To: | Remick F NRC OFFICE OF POLICY EVALUATIONS (OPE) |
| Shared Package | |
| ML20023A459 | List: |
| References | |
| FOIA-82-611 NUDOCS 8203180052 | |
| Download: ML20023A456 (3) | |
Text
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] + ( MAR 0 21932 MEMbRdNDUM FOR:Forrest J. Remick, Director Of fice of Policy Evaluation /.) THROUGH: William J. Dircks, Executive Director for perations .FROM: Harold R. Denton, Director Office of Nuclear Reactor Regulation
SUBJECT:
SAN ONOFRE UNIT 1 - STEAM LINE BREAK AND SEISMIC UPGRADE New information, identified as a result.of ongoing SEP topic reviews, has caused the sta'ff to question the capability of San Onofre Unit 1 to safely shutdown for postulated steam line breaks regardless of whether the failure is sei,smically induced or not. The plant is shut down for approximately three months for seismic upgrading of two 'sf.ructures.(North Turbine Buildin'g Extension and West Feeddater Heater Platform) and for steam generator tube j -( inspection.
- Resolution of related steam line bre'ak issues has 'been given '
l high priority and San Onofre Unit 1 will remain shutdown until we are satisfied. The ste'am system at San Onofre Unit 1 is rather unique in that all three steam generatois. are connected through a cormon main steam header inside containment and the main steam isolation valves are manually operated. Thus, a steam line break, either inside or outside of containment, will result in-blowdown I of all three steam generators, eventually cause.the ' loss of the steam driven ' auxiliary feedsater pump due to a loss of steam pressur'e and require the addition of cold water. to dry. steam generators to remove decay heat.- Decay heat removal requires the use of the remaining electric auxiliari feeddater The present system does not meet single failure criteria,. e.g., the l ~ The staff is also questidning pump.- loss of the electric auxiliary feedwater pump. the integrity of the the steam generators, control of plant cooldown by ' operators ~. and and the. ability of the manual main steam isolation valves to isolate postu-In addition, the train feed lated steam line breaks outside of containment. pumps are not available for feeddater addition because they are part of the ) ,ECCS is requir,ed for steam line brea s to assure boration of, k ECCS system. the reactor to preclude return to power and to add water to makeup for' reactor coolant sy' stem contraction. 16, 1981 decision to deny This steam line break issue is related to r:y November two 2.206 petitions on seismic and emargency planning issues at San Onofre Unit If a seismic event were to cause grosrs f.ailure of 1 in the following sense. the East Feedsater Heater Platform, and thereby cause a steam line break, ECCS system could not be assured since ECCS piping cormon to both trains is under. this structur go W XA CoTp Hos BW5ent tov 6R o ~ dn g
- Forr'est J. Remick
-2.* 3 ( Thi st'eam line break of concern is not the main piping, which is located in the North Turbine Building Extension, but is branch piping. It 'may be that the 'ECCS is not essential for breaks in branch piping, which is smaller. The manual main steam isolation valves, located in the North Turbine Building Extension, may be able to isolate branch line breaks, however, t.his has not-been confirmed. We dre presently evaluating the licensee's analysis. Two other developments have the potential to complicate the tim'ely completion of seismi'c upgrading of San Onofre Unit 1. First, the licensee is not meetin'g schedule commitments for submission of analysis for staff review. The analysis of all safety related structures was to have been completed by January,31,1982. The licensee currently estimates completion by April 30,1982. Second, the anal.ysis methods used thus far for evaluation of masonry walls and yesonry structures, dq rtot appear area,n%1e. By letter dated February 17, 1981, the staff ^ proposed two options to resolve this issue. We intend to meet with tW5 -licensee to evaluate the impact upon the schedule for seismic upgrading of 'Tese two recent developments-t We would be pleased to meet with your staff to discuss '.hese matters in mre detail. Tlie contacts are Gus Lainas (x-27492) and Bil{ Russell (x-29794). 97/W q r Harold R. Denton', Director . ", (.'. Office of. Nucl lear Reactor Regulation e ens G e 4 1-i e W ~
~. nPri1 2. 'M2 y..o 7 f / 4 ket No. 50-206 j05, 04-009 Mr. R. Dietch, Vice President Nuclear Engineering and Operations . Southern California; Edison Company ~ ~ 2244 Malnut Grove Avenue' ',7 f. ~ 4 1, : 6.'?: Post Office Box 800 .91770 ' i-t.f O....
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Dietch:' Y '- ~ ~ '..SU35dCT: SAR ONOFRE UNIT,1 SYS,TpCRESPON5k AND STkUCTU)LAL CONCdk The NRC staff is evaluating the response of the San Onofre Unit 1 to: - f Several concerns :have '. ~~ h several ' events as a part of ongoing.sta. f reviews. arisen rela' ting to the capabili,ty of this. facility to accomodate
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1.inear inelastic time history analysis methodology used for the evaluation' .and.qualificat' ion uf. masonry walls at San Onofre Unit 1, and the schedule. for the seismic. tipgrading of the facility. These concerns are discussed? ~ e10w. - 2 / . r:- . Main Steam Line' Break Analysis ~ There.are many possible steam line break lo' cations in the S'an Onofre Uni.t 3.. W..:<4W#- in the blowdown of all three steam cenerators3-L. e,4.D . piping that.will resultThe' staff's concerns r'egarding'this issue include th'e E J decay heat fo.llowing a postulated steam line break,'the effect of the ' addition of cold auxiliary feedwater on the hot int'ernalscof the steam'-V :l.;' : ,'.O generator, and the possibility that a seismic event that in ,. ' /- . steam lines that run under the platfom and also potential,ly. fail the sa'fety., l. injection, piping that. runs under this platfo'm. The need for modifications to the. east feedsater platfom to upgrade its seismic capacity have been identified and we expect that the completion,{ .of these modifications will be made by January 1,1983, unless adequate justification for continued operation beyond this date is provide accepted by the NRC staff. In addition, the steam line issue in your letter of February 2,1982. break issue was the subject of a meeting held with your representatives ( i ori March 2,1982. i -+
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i r; O i bd ' - Mr. R. Dietch . /- .y Analysis of' Masonry Wal.ls Your submittals of January 11 and January 15, 1982 describe your methodology for a non-linear inelastic time history analysis of the masonry walls at San Onofre Unit 1. At a mee' ting on January 20, 1982, your representative ~s discussed this methodology with the staff. Our letter dated February 17 ~ I'982 stated that, at this point in time, we cannot accept your proposed . analytical methodology as the sole basis for evaluation and qualification - of the masonry walls. We are evaluating your response dated March 15, 1982. y Seismic Upgrading Schedule':,$ .,V.~ n .,r. By your Tetter of N'ovember 3,.1sSM you' comitted to' complete the" seismic ' - analysis of structures importintMd safety by January 31, 1982. However, * :: ~ 'by -your latter of February '9, J 982,'you informd us of 'a sl.ip in thit date for.the com.pletion' of the analyshs, to April 30, 1982. ~ '~ Due to-delays in the compietion of analyses, it appears that the$ sche'dhle ~ for compTetion' of' the remining analyses 2nd implementation,of modi,fications ~ by January 1,1983 wi11 not be mt and we have not received justifi, cation _for continued operation.beyond this date. As a result of the above concerns, the staf ' req iles that you p vidh '. / the follopin'q irifo,rmation ih writing under oath or affiration by April.130, - 1982 pursuant to.10 CFR 50.54(f) to enable the Comission to deterBine. (' whether or not your license should be madified, suspended or reyoked: ~ l., Information and comitments nece'ssary to satisf.actorily - resolve the stdam line break iss'ue, including.the ade-quacy of (a) steamline isolation provisions,.(b) decays;p jfi'}, ' ~. C heat remaval capability, and (c) corpor)ent integrity.-{ip].r.J r., f,- If it appears that this issue cannot be'yesolved prior tog.- the startup from the current outage, provide your schedule for resolution and four, justification for continued operatiori of your facility following the current outage while the ' ' ),.' ~ steam line b,reak issue is being resolved' 2. Information' and comitments necessary to satisfactorily. ~,' resolve the nasonry wall issue. The three principal safety e concerns associated with the masonry walls are: (1) gross failure of walls and their effect on safety related, equip- . ment, (2) the effect of large displacements in walls '(predicted by your analysis) upcn hafety)related equipment attached to or penetrating walls, and (3 the effect of missiles from any spalling which may occur if walls are not upgraded to remain fully elastic under postulated seismic loadinds. If it appears that t'his resolution, - C- cannot be achieved prior to,startup from the current outage, provi,de your s,chedule. for resolution and your justification for cont-inued opera, tion of your facility following the current ' outage.while the msonry wall issue is being resolved. i
A description of actions taken t'.o ensure 'that schedules .3 ' in your Hovembe'r 3.'1981 letter,for completion of setsmic analys'es of components and systems will not be delayed. 4~ Your current schedule for meeti,ng your commitment to complete the seismic upgrading of San Onofre ~ Unit 1; including the East.Feedwater Heater Placfonn and the Seuth Turbine Butiding Extension, by January 1..1983. If all the required m d f
- tions, can'not be completed;Bf January 1.1983,,o i icaprgvide.your,.
~~ P-whedulelfor compie'tlon and your:justug,eag on for ..,: g -, g cg, i .r. ' continued operation 6n*].t,he modifIcati,ons are, ,,. c. i . 1-
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E.. L compieted... ,. q.,76 ( m The stdff idil co~ sider theinsvers to this request fo 1 fo { Ton T n whether ypur T Teehse.to oper' ate San ~ noir 'deteratn.tng'uspended or revoked. modified.,s s
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