ML20126B475
Text
{{#Wiki_filter:.., i* .,.s .:ct. :. 3. s;. ?. .+, ;r..'L... y.p, e. j; ; 3. o, .j s.. c, -. q. s _-.:c:: - 77.-'_ % L.. ' 4;; : ,.y ;~ l y.; ::,,'. ; ~. l l >,3.:p;%-
- .'l c-INTERIM REPORT OF THIRD PARTY. REVIEW'OF'7.'-
- c r-9 ;. (!ib.?J - { THREE MIpE ISLAND, UNIT 1, STEAM GENERATOP REPAIR e l- " ~O J f / 8 /f A C Z ) d S '. y;< T ygun: E,G. LaA4 L W ( t s R. F. Wilson - Vice President, Technical Functions-l GPU Nuclear l m, .= }, , Frepared by N m THIRD PARTY REVIEW GROUP: .c v .e l Stephen D. Brown d. .).m Stanley A. Holland V 72
- 9 Arturs Kalning E
'y u Willian H. Layman S David J. Morgan
- u Richard W. Weeks Edwin J. Wagner - Chairman.
,s t 4 l / Submitted for the Review Group p U W by: i , p.g. wer.. date* 9/27/82 l 8506140112 850125 PDR FOIA DETJENS4-897 PDR . _.6/
...,.,. i ' ' 9;.; 1 i 4 PURPOSE: This is an interim report of the Third Party Review Grodp to ! - i. . + n. l Q aluate a cart of the TMI-l Steam Generator Repair Programh=...'[),[Ei5'hh that relating to the safety of conducting the proposed repair i. t of the steam generators while the plant is in a cold shutdowni-i *; f l..y, fi condition, including the effects of the repair on the steam ; '(" f'i I generators and on the' remainder of the TMI-l plant. This 'h*1 i! i interim report was requested by R. F. Wilson, GPU Nuclear,- .L on August 10, 1982 to obtain the Review Group's evaluation of.i ' ' ' ' Y' this part of the steam generator program concurrent with decisi,on making on conducting the repair in THI-1..As GPU T [., ? - Nuclear completes the remainder of the overall repair. program, M the Review Group will report its evaluationcof the remainder. of Scope of Review defined in the Charter for this Third.' ( Party Review. i CONCLUSION: Based upon the information developed by the repair program and j l summarized in the Safety Evaluation, the Review Group concludes,' I. that the proposed repair conducted on the TMI-l steam generators a!. 4 1 in conformance with the control systems described will not have adverse effects on the nuclear safety related items of the plant (including the steam generators) in the cold' shutdown i condition. This includes consideration of potential hazards ' from: f 1. Missiles generated by the explosive process. i 2. Introduction of chemical residues in the steam generators, reactor coolant system or the reactor plant ambient. 3. Transmission of pressure pulses through air oristructures to sensitive items such as previously expanded :tubesi t' L previously plugged tubes, other stcan generator structures - or safety related instruments and controls. (', 4. Handling of explosives in nuclear safety related' equip. ment or structures (We note that no Review Group member, is expert in handling explosives. Acceptance of the' f response to this potential hazard is based on the procedure controls described in the-Safety Evaluatica, their compliance with the Laws of the State ofiPennsylvania and tne exclusive use of blasters licensed in accordance :'t' / with that Law).
) . c. 6,., - s. t 5. Occupational radiation exposures. a ;; .d.8.n i This conclusion applies only to the safety of the plant, including the, steam generators, of conducting the proposed repair Wilai the t.,..; i! plant is in the cold shutdown condition.' This conclusion does 0.*', 4 b. not apply to the safety of returning the plant, with steam : ",, { I to service.. J. gene,rators repaired by the proposed process, Although efficacy of the repair is not a consideration.in the safety j ~ ~ S :t l of conducting the repair, it will be important to the safety'of - + returning the plant service. GPU. Nuclear may elect to proceed ! :. - I-t .The with the proposed repair at substantial economic cost.: -r Review Group therefore considers it appropriate to render an 3 opinion now about.the efficacy of the repair sar it may affect future safety considerations. Tne Review Group believes that the proposed repair, after. completion. of the on-going qualification and when conducted in accordance with 't the control procedures, has a high probability of producing tube-: i-to-tubesheet joints adequate for a safe operation of the plant. However, based upon industrial experience with expanded, unwalded se tube-to-tubesheet joints in high pressure heat -exchangers, it. is p l expected that greater leak rates will occur during normal operation '. .,I than typically experienced on new nuclear plant steam generators. - The Safety Evaluation covering return of the plant to service should'" i consider this possibility 1 f APPROACH: I 1982, R. F. Wilson of GPU Nuclear established a On April 12, Third Party Review of the TMI-l steam generator repair program.. A Charter was supplied which defined the purpose, scope, member-The evaluations of the . ship and operations cf the Review Group. Review Group have been conducted in conformance.with the. Charter.. The membership of the Review Group, selected by GPU Nuclear for expertise in the following technical specialties is: Specialty Name Affiliation _ f Steam Generator E. J. Wagner . Burns'and Roe,'Inc. Design Chemistry D. J. Morgan Pennsylvani~a: Power &. Light.. R. W. Weeks Argonne National Lab Materials A. Kalnins Lehigh University / Stress Analysis Safety Analysis W. H. Layman EPRI - NSAC Plant Operations S. A. Holland Duke Power Co. Non-Destructive S. D. Brown EPRI - NDE Center Examinations wh. EE
~ ~ ~ 'Q.#,, ,7{t,i 8.. .7..,1,, A p... 9, 3-E. G. Wallace of GPU Nuclear is a non-voting member who serves. -[..as lia members have been present and participated in all meetingslof the ;l'M W II" ' " i' '! P ' Review Group.. It should be notac that the members act as independent individuals.. - <. on this Review Group. Neither.their individual statements:nor-7'. T* ' i t 5ed.. <) A :l. r .their contributions to any reports of this Review Group are n erp]1{; [,T, to represent the opinions or conclusions of the organizations.c. '7'," with which they.are affiliared. The evaluation reported in this interim report was conducted 9!h,F concurrently with evaluation of the. full. Scope of Review.5efinedtin. g.. ,1 f The Avaluation was conducted using reviews of ,,l, ' I,* ' the Charter. pertinent documents, submittal of written. questions,to GPU Nuclear, written responses by GPU Nuclear, review of specialty topics by individual members, presentation by cognizant GPU Nuclear or contract,or personnel, Review Group meetings.and Executive Sessions of the Review Group. members only.. Ful'li day i meetings of the entire Review Group were held on April.23, -{, s May 20 and 21, and August 24 and 25, 1982. 0; c The focus of the evaluation of this interim report was the Safety 'k Evaluation of the TMI-l steam generator repair distributed to.the, - 20, 1982 and of<its . 'j Rev'iew Group (E. G. Wallace letter of AugustThe proposed repair described in .r~ j reference documents 1, 2 and 4). f' this Safety Eva:uation is the explosive. expansion of the. top 17 ore. i 22 inches of the tubes within the top tubesheets of both. steam .,,'l' ~ The repair will be made on all, tubes which-willibe.' generators. returned to service. The explosive expansion creates new pressure boundary joints between the reactor coolant and steam-side of the steani generators. i l l COMMENTS: During the review of the Safety Evaluation and supporting documents, I These : certain observation,s were made by the Review Group. comments and the GPU Nuclear responses could be~ pertinent toIthe l l conclusions of the Review Group in assessing the return of the plant to service. They are therefore documented as follower. l The Safety Evaluation states that the repair joints wiIl. l. be leak tight and meet the design
- bases of the As the Review Group stated under original joints. Conclusion, the repaired joints will probably be' adequately l
However, the joints leak tight for safe operation. should not be expected to be as leak tight in normal. l 'f operation as those of typical new steam generators. I .s ^ e NW'N *#O e -e FWmN '*s G e y,
r ...i-- l ,-.. Q ?, 6.." ;
- s.
The Safety Evaluation for the return of the plant to, :w,g p $;. 4 service should consider the potential-for highe'r isak., , jy. rates from reactor coolant to steam systems and the.> ,,,,g oy g. handling of resultant radioactivity discharges'such ais,:..Ju N ; - M fron; the condenser air ejectors." GPU Nuclear,.agrined.. pf.,, f.;c yy 2. Although indirect measurements provided some indicatione;,'.3,c.,-g, tne repair process qualification does not contain a . '., ; ; d. j;',, direct metallographic examination to verify that the ,a,.. metallurgical structure of the tube material. iri the , ;,., a.....,,. expanded region is not degraded by tne expansion. ,,.,,,,.7,. GPU Nuclear said that such,a metallographic examination e.,. ( would be included in the qualification. g,, l 3. Paragrapn 6.1 of the Safety Evaluation discusses i. residues left on the steam generator surfaces by p,(,, ;j ' explosive expansion. The Review Group understands'that the testing at Mt. Vernon showed greater amounts of residue than expected based upon mock-up tests. Some 1,, cleaning is now expected to be necessary. GPU. Nuclear.
- ~
further advised that a material called Immunol is under I..: i consideration as a coating to facilitate removal of residues. It would be applied to the tube surfaces ,e before the explosive expanding. l [ The Review Group suggested that specific. limits and-appropriate check methods be included in. procedures to preclude existence of detrimental contamination from. either the explosive residues or Inununol after completion of t.he repair. GPU Nuclear agreed. 4. Paragraph 6.5 of the Safety Evaluation indicates that :the j steam generators w:.ll be isolated by temporary plugs from the reactor coolant pystem during repair.6 Howeverc [ a cognizant contractor person stated that,-based.upon-the Mt. Vernon testing, temporary plugs might not be used. l The Review Group considered it.important to-assure thatt. contaminants from explosives not be allowed ter travel into the reactor coolant system. GPU Nuclear agreed and reiterated that the temporary plugs will be used. Y j 5. Paragraph 8.0 of the Safety Evaluation discusses the quality-assurance and quality control for the; repair. 4 . The Reva.ew Group asked whether a quality plan existed specifically for the repair. GPU Nuclear adviced that the quality actions are an integral part of each procedure e -*g---- ._.---__m,.__w,.w_.---.".-".*w*s.----,,
' r.; .s ,,,.i , J....:*;,1 i-V ? fc.,*. 8 L 6 s . i. 5-
- j and that all the repair activities wouM be. conducted.
',3, cr.ph.15]r;,i in accordance with written ' procedures and, the.TILI-1.." 4 Jr: iib R yp .y;y;,yj.. Quality Assurance Plan. A specific quality check of.the adequacy' of :tho' oveirall ; t!y. 4 bl jn. i explosive process (type of explosives, amount of. charger..i., c,,.i i., charge condition, correctness of. assembly, etc.) was it. - a g,, pu n suggestad by the Review Group as'the type of check that .,. ;.. g,. g. might be identified by a specific quality plan for -the s... -,. 5,,i.;c 2 . e repair.. The intent of such a check wouM be to-detect ; ; ; m. qrn. any reptir process failure early rather than during i ,,+@ testing at the completion of. repair. This specific check p ip.m an might be conducted by actually explosively: expending a ,c,.2 , i. 3. p g : test joint periodically with production. explosives and. esi.4 i.. :;S;,, equipment. GPU Nuclear advised they would assure that t.:q pc,,; the integral quality provisions of their procedures .u.- constitute an adequate quality plan for the repair.and thakiap W q, overall quality control check such as suggested would.. .. c...,;.. ;, be incladed. e e e e e 9 e 1 e r __ __}}