ML20062H710
| ML20062H710 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 07/08/1980 |
| From: | Halapatz J Office of Nuclear Reactor Regulation |
| To: | Gamble R Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20062H675 | List: |
| References | |
| NUDOCS 8008210276 | |
| Download: ML20062H710 (5) | |
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f 'C, UNITED STATES f ',* .., ' i NUCLEAR REGULATORY COMMISSION
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. C WASHWOTorv, 0.0.20555 s, ff July 8, 1980 MEMORANDUM FOR: R. M. Gamble, Section Leader Conconent Integrity Section Materials Engineering Branch FROM: J. Halacatz Materials Engineering Branch
SUBJECT:
DIFFERING PROFESSIONAL OPINION CONCERNING REDA!R OF SEQUOYAH UNIT ONE PRESSURIZER RELIEF PIPE - INTERIM COPMENTS This memorandum submits written coments for the record concerning views expressed by his immediate supervisor and others in the chain-of-command in the course of resolution of a differing professional opinion. The differing professional opinion was expressed in the menorandun, Halapatz to Pawlicki, dated June 16, 1980, subject " Expression of Differing Professional Opinion in the Matter of the Adequacy of Sequoyah Unit One Weld Drawbead Repair of Pres-surizer Relief Pipe." These coments are submitted in accordance with SECY-80-164. Enclosure 1, Section B.8.b., dated March 25, 1980.
The minority submits cor: rents to the following memoranda:
- 1. " Differing Professional Opinion - Sequoyah Pressurizer Pipe Weld," Gamble to Pawlicki, dated June 27, 1980.
- 2. " Comments on the Differing Professional Opinion on Sequoyah Weld Depair of Pressurt:er Relief Pipe,," Pawlicki to Noonan, dated June 27, 1980,
- 3. " Comments on the Differing Professional Opinion on Seouoyah Weld Repair of Pressurizer Relief Pipe (J. Halapatz)," Noonan to Vollmer, dated June 30, 1980.
The "anble to Oawlicki Memorandum
- 1. The purpose of the radiography was to detemine if the cressure boundary was penetrated. This determination is necessary to cualify exemotion from post weld repair system hydrostatic testing recuired by the ASME Code.
The Code (!WA-4130(b)) comits the owner to evaluate the suitability of the welding procedure to be used to nake the repairs. The Code (IWA-4130(c))
states that repair programs shall be subject to review by the enforce ent and regulatory authorities having jurisdiction at the plant site.
Presumably the mockuo of interest was made to satisfy these recuirements.
If this was not the case, then no basis as required by the code existed before tne fact to implement the weld repair.
The radiography, which was performed, was intended to determine, after the fact, whether or not the ;:ressure boundary was cenetrated. Radiography is B O U f C'1 D
- R. M. Gamble -
essentially meaningless for the characterization of degree of sensitization.
The detemination of whether or not the pressure boundary was penetrated is an important technicality, which must be addressed within the context of 10 CFR 50 Appendix B. Third party inspection, which was randated by the NRC for Secuoyah by the Rubenstein to Parris memorandum, dated September 21, 1979, subject, "Cualification of Inspectors, Inspection Specialists, and Inspection Agencies for Sequoyah," provides for an expedient resolution of this issue.
An atherized inscector affiliated with TVA's authori:ed inspection agency should view the radiographs of interest and make the official interpretation.
- 2. A significant disparity is noted between the safety significance involved as regarded by the licensee and by the majority opinion as expressed in the Gamble to Pawlicki menorandum. The licensee's safety implication, as stated in nonconformance report NCR SWP-79-S-8. states that failure of the piping of interest could lead to an uncontrolled blowdown of the reactor coolant system. This view is in contrast to the majority view that if crack-ing occurs, operating experience indicates that IGSCC has been detected by either inspection or leak detection before excessive leakage results.
Perhaps the difference lies in what is likely to be leaking, steam or water.
- 3. With regard to the statement that no cracking incidents have been experienced in PWR pressurizer lines, the minority recalls that not too long ago Ginna had some sort of a problem in this area. Perhaps the majority could provide some enlightenment in the matter.
4 In equating the potential service experience of the repair welds of interest to that of the population of full penetration welds in LWRs, the majority's attention *is called to cracks which have occurred to the astonishment and consernation of experts. The minority cites, in reference.
"Cperating Experience Memorandum No. 17, Pipe Cracks in Sorated Water Systems of TMI-1," Eisenhut to Schroeder, October 5, 1979. What is particularly disturbing in this case is that the environmental conditions experienced by the material aoparently have been accepted generally as non-aggressive.
A major difference in philosophies is obvious in this issue. The minority's view put simoly, is that the public would be better served by addressing potential worst case materials problems during construction rather than determining the causes of material failures occurring in service. The ninority finds little solace in the association by the majority of small leakage rates with inservice IGSCC and small leak detectability with the maintenance of system safety margins. The minority view seeks to prevent cracks; the majority view seeks to provide accommodation for cracks when
' they occur. Undoubtedly the public interest would be best served by a meld of the two views.
The minority finds the in situ metallography performed inconclusive. The minority sees, even in the Xerox cooies of photomicrographs available to him, evidence of severely smeared metal and has serious doubts that the true
si w
. N R. M. Gamole L microstructure was developed. The minority is at a loss to exclain how NRR could meaningfully interpret the in situ metallography as acceptable.
Within this context, the minority finds that laboratory examination and corrosion testing of actual piping material is much more convincing that the most inspired pontifications as to why a material shouldn't crack.
In this light, if not beat sample material, then mocked-up archive material, whose identity should be reassured by 10 CFR 50 Appendix B requiremen'ts, should be examined and corrosion tested.
The Pawlicki to Noonan Me orandum n 1
1.
The majority statement that the primary purpose of the nockup used oy TVA was to experiment with the effectiveness of the straighter:frg process itself, and very little can be deduced about the condition of the pressurizer relief pipe from examination of the mockup is contradictory. The majority's acceptance of the repair via the mcmorandum, Pawlicki to Rubenstein, dated December 4,1979, subject, " Tennessee Valley Authority, Seousyah Nuclear Plant, Unit No. 1" was premature in that it preceded the majority consultant Gustafson's January 16, 1980 meeting with TVA, which was addressed in the memorandum, Gustafson to Pawlicki, dated January 25, 1980, subject," Trip Report of Visit to Tennessee Valley Authority Sequoyah Nuclear Plant, Unit-l." In his statement of the problem, Gustafson made reference to the matter that TVA's request to NRC for approval did not provide background details on the repair procedure employed, details concerning weld procedure qualification, non-destructive exanination, information on the susceptibility of repaired area to intergranular stress corrosion cracking or any consideration of residual welding stresses. Gustafson further stated that approval was held up until additional information could be obtained and evaluated.
- The minority notes notes that Gustafson did make significant deductions based on the mockup. The minority calls attention to the memorandum, Pawlicki to Rubenstein, dated February 23, 1980, Subject," Tennessee Valley Authority, Secuoyah Nuclear Plant, Unit No. I Realignment of Pres-surizer Relief Pipe," which recommended that the minority meet with TVA and examine the metallograohic samples in question. It is to be noted that only available metallographic samples in question at that time were those parted from the mockup. The memorandum, Pa# i:0 to Rubenstein, dated March 3,1980, subject " Metallurgical Er no :ien of TVA Seoucyah Nuclear Plant Unit No.1 - Weld Drawbead ReO % 4 i assurizer Relief Pipe Mockup,"
specifically identified that the pura e # ' .2 minority visit with TVA was to perform a metallurgical examinat u o' ', vockup used in qualification s of the weld drawbead realignment of i?.e Sequoyth pressurizer relief pipe.
s At this point, there is little doubt of the majority's acceptance of the mockup to qualify the repair welding.
The minority's metallographic examination of the nockup, hewever, disclosed, in part, that the weld was fully penetrated, thereby disqualif7'ng TVA for exemption from system hydrostatic testing.
k R. M. Gamble -
In the ensuing controversy, which developed as a result of the contradictory findings, the compromise was reached that in situ examination and reradiography would be performed to (1) determine whether or not the pressure boundary had been penetrated and (2) determine the degree of sensitization in the production repair. It is the opinton of the minority that the determinations that have been made are inconclusive, as addressed in the memorandum, Vollmer to Denton, dated July 2,1980, subject, " Differing Professional Opinion Concerning Repair of Pressurizer Relief Pipe at Sequoyah Unit One."
- 2. The majority votes against taking boat samoles. The minority notes that 18 pieces of tubing of the same size and heat (C7492) as the production repair were procured, as shown in TVA certified material test documentation. An obvious alternative then, would be to mockup some of this material using the production repair design and weld procedure. Laboratory metallographic -
examination and corrosion testing (in .2 ppm oxygen-bearing steam) of ID and tinswall samples parted from the mockup should provide definitive test data on which the NRC evaluation of the weld repair should be based. Put simply, it is the minority view that engineering judgments, when possible, should be based on test data rather than opinion.
- 3. The majority votes that third party inspection be performed since it nay help remove remaining minority doubts. Minority doubts notwithstanding, attention is again called to the memorandum, Rubenstein to Parris, dated September 21, 1979, subject, " Qualification of Inspectors, Inspection Specialists, and Inspection Agencies for Sequoyah," which directs that TVA institute third party inspection for Sequoyah.
The Noonan to Vollmer Memorandum
- 1. Given TVA's statement of the safety implication involved, viz., that failure of the repaired piping could lead to an uncontrolled blowdown of the reactor coolant system, augmented ISI would appear not to provide the necessary as-surance of safe shutdown. Augmented ISI would address failure in terms of slew leaking cracks, a circumstance which TVA apparently did not have in mind when nonconformance report NCR AWP-79-S-8 was written.
- 2. With respect to the majority opinion that the weld drawbead repair of the tyoe used at Secuoyah is a common and acceoted method of repair, the minority offers the purely hearsay infon.ation that TVA considered the procedure unicue to the extent that a technical paper describing it was under consideration.
7 S
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/ Joseph Eala at Materiils e Divisi6 h ginee 'ngingBranch Enginee For cc's, see attached sheet
~
R. M. Gamble cc: H. R. Denton D. G. Eisenhut
/R. H. "ollmer V. S. floonan R. L. Tedesco S. S. Pawlicki -
A. Schwencer C. Stahle
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/, f * * %q'o UNITED STATES
- l' c% v'-",, [,ii NUCLEAR REGULATORY COMMISSION ADVISORY COMMITTEE ON REACTOR sAFEGUARCs k .g ,/ WASHINGTON. D. C. 20S55 9 ~.- p
%* July 15,1980 4
The Honoracle John F. Ahearne Chairnan U. S. Nuclear Regulatory Commission Wasnington, D. C. 20555
SUBJECT:
RE00RT ON THE SEQL'0YAH NUCLEAR PCWER PLANT, UNITS 1 & 2
Dear Dr. Ahearne:
Juring its 243rd meeting, July 1G-12,1980, the Advisory Comt::ee on Reac::r Safeguares comoleted its review of the acplication of :ne Tennessee Valley Au:ncrity (hereinafter refer ed to as the AO licant) for authori:sti:n ::
ocerate ne Sequoyan Nuclear Plan:, Units 1 & 2 at full :ower. Tne Oc=i :ee nad 0:nsicerec as:e :s of :ne a:clica:icn curing its 242nd meeting, June 5 ,
'.980; 236:n mee:ing, Decem:er 5-a, 1979; 229:n mee-ing, May 10-12, 1979; anc 228tn meeting, A:ril 5-7, 1979. A tour of :ne facility was mace :y memoers f the Succ:mm1::ee en January 24, 1975 anc :ne as lica:10n sa: c:nsiderec at Subccmmittee meetings en July 9,1980; June 2,1980; Novemoer 5,1979; anc
. March 12, 1979. During its review, :ne Commi: ee nac :ne benefi: of discus-sions with re:resentatives anc consultants of the Acolican:, the Wes-ingncese Electric Cor:oratten, and :ne Nuclear Regula:Ory C:=1ssien (NRC) S:aff. The
- mmittee also nac :ne Deneft: of the documents listac. The Commi: ee recorted on interim low power operation of Uni: 1 en Decemoer 11, 1979 anc en' a ::ns: uction oermit for this :lant on Fecruary 11, 1970.
In its letter of Jecemoer '1, 1979 the Commi :ee a crassed Ne ro;csec s:ecial 1:w :ower :es rogram, to :e carriec cu: On 'Jni: 1, :ne seismi:
reevaluation of :ne Secuoyah clan:, actions on re::mmencations resulting # 0.3 the review cf ne acciden a :ne Tnree lile :sland Station, Uni: 2, anc actions en various generic croolses. These generic ro:lems were furtner ciscussac in the Co=ittee's recert, " Status of Generic Items Relating to Lignt-4a er Reactors: Re:cr No. 7," ca ec v aren 21,1979. Tne Comittee's re: mmencations in its Decemeer 11, 1979 le: ar are also a::licaole :: ';ni- 2 ex:e : na: :ne special law cower test ar: gram will no: ce re aatec on uni: 2.
52 s:ecial icw :ower tes Or: gram has :een reviewe :y iestingn:use Ele : 4:
1:r:: ration and :y :ne 1RC Staff. Tne 20:1fcan tegaa nese as:s oc July '1,1950 anc :ne Ac:lican:, nestingneuse, anc :ne '!RC Staf' c1' review Se esul s Of :nese es:s. I: is ex:ectec na: :ne acci:1:nal :: era :r training anc :: era r ex erience m rove :: e 3eneficial.
I bc/2 ba l /
[~D 7i is [wN O u [? g[
iioneracle Jenn F. Ahearne July 15,1980 The Co=i tae has reviewed and re:orted on NUREG-0560, "MRC Action ?lans Develooed as a Result of :ne TMI-2 Accicen:," Draf: 3. Tne status Of :ne A plican 's : moliance with the NTOL licensing requirements as well as a numoer of non-Tri!-related items were reviewed during its 243rd mee:ing. There ~
are a number of both non-TMI and TMI-related recuirements not fully resolved.
Both the NRC Staff and the Applicant expect tna: :ne c:::lete resolu:f on of
- nese cu: standing items is essentially a procedural er documentary matter wnicn will :e c:mpleted witnin a very few weexs. Tnese items snould be resolvec :: :ne satisfaction of the NRC Staff. Tne C mmittee wisnes :: be k.e:: informec. The Cc=ittee believes tha :he im:lementation of :ne Action Plan as it will be reali:ec at Secuoyan is acecuate :: assure :ne safe
- ceration of :nis plant.
The Cc=t: ee, in its :taren 11,1930 re:or: On the NTCL i .ams, re :mmencee
- na: :ne licensees ceveico reliacility assessments f:r their :lants anc na: :esign s udies of Ocssible nyce: gen c:ntrol and fil ered sentac : ntain-ment systems be recuirec. The Acclican: nas c:ncucted stucies of a number of means for hycr: gen ::ntr:1, and as an interim measure, nas pro: sec installa-tien of a cistri:utec array Of igni:icn seur:es wnien i; ex;ec s :: nave in Oiace :y ,ne f ail of 1980. Tne A::licant has conclucec :na: y :nis means ne containment aculd be aole Oc :::e with :ne ::ressure resulting fr:m :ne
- m:us:icn of nycrogen releasec y ne reaction wi:n sa:er Of u: :: abcu: 7 0".
of :ne :irconium in the core. Tnis com ares witn the 25". wnich :ne contain-Tent coule coce witn without any acditi:nal control meast.res anc :ne 30 to 50% estimatec :: have reacted in the accident a IMI. Tne NRC Staff :lans to revi ew the reccsec system in ce: ail Oc assure itself of its efficacy anc
- na: all safety as:ects have een aKen into ac::un:. Tne C;--.i::ee aisnes to be <eo: informed of :ne fur:ner conclusiens reacned by :ne Staff anc :na A licant in :neir continuing consiceration of these matters. The Acclicant nas ::ncuctec reliacility assessments of some features of :ne :lan anc nas
- nsicerec some as;ects of :ne effec.s Of a :ossi:le filterec ventec contain-ment. Incugn the acrk ace:m lisnec :0 date is limite: in 3:0:e, :nese stucies are cefinitely res;onsive : :ne Commi tee's rec:mmencati:ns :n :nese
- cints. The A:alicant rocosas to ::ntinue s:ucies of :nis nature anc ::
extenc the range Of :neir acclicati:n. While :nese efforts, as well as :nese concernec with hydrogen c ntrol, snoule :e vig rcusly pursuec, in view of :ne
- mmitments mace by ne A: licant, it is :ne :cinion of :ne Committee na:
neir :resen incem:lete status neec nc: celay :ne issuance Of a full :cwer
- erating license.
Sarly :nis year a di'ferin; or:fessi:nal ::ini:n was advan:e cy a mem:er
- f :ne Z 3:af' c:ncerning ne at:e: acility Of a :ar-icular ael: re: air M
- ne :i:inc :: a :ressuri:e- -eld ef salve :f Secucyan Un : N o . '. . 411 0:ner 4
- aalifiac'anc res:onsi:le memoers of ne NRC Staff, as neM as Or:fessional
- ersonnei en :ne s af# Of :ne A::licant. : axe :ne :Os- ::n na: ne asl:
snoul: :e regar:ec as acce::stie since :nere is no evi en: eas:n any '-
sncul: n: be a: leas: as ca:a:le as ::ner (mcre stancar: nel:s an :n aculd
O .
Honoracle Jenn F. Ahearne July 15, 1980 oe considered ac:e :aele. The differing c: inion is nc na: :ne weld is cemenstraoly less cacable : nan it neec ce, cut 1) tha: :ne evidence availacle is inconclusive en :nis cuin:, anc 2) that more specifically relevant infor-mati:n could be oc:ained without sericus cifficulty. Tnis 00uld ce done Oy cons ructing a mock-up of :ne weld in cuestion using material anc procecures as similar as ossible o : nose wnicn accly in -he actual case and sucjecting
- ne moc.<-uo :: a :nrougn-wall metallegra nic examination. Tne results :f nis examination could nen (for example) De ::m:ared witn : nose fe:m a full
- enetration neld in the same material, wnich nas been performec in ne stan-car: f asnion anc deemec ac:ectacle based on satisfactory operational ex:eri-ence witn wnien the majority coinion nas compared the :resen welc. This has net been cone. The Committee coes not consicer it c be particularly likely
-hat this weld re: air cresents a sericus hazard; but i :ces :elieve the evicence en nis Ocin: c:ule ce im:reved. The Committee :elieves :nat, in
- ne intares: Of resolving the cuestien :na: nas been raised ne . .aximum ex en: reacily :ossicle, ste:s Of :ne na ure cu: lined sncul ce ta<en.
.1e Committee believes, :na: if due consiceratien is ;;ven : ne items mentionec acave, ne Secuoyan Nuclear Plant, Units 1 an: 2 can :e :eratec at levels u: :: full :cwer without uncue risk :: :ne neai n an: safety Of ne :uclic.
Si ncerely ,
e
. ,/'
Milton S. Plesse:
Chairman
References:
II' Tennessee Valley Au nori y, " Final Safety Analysis Re:O rt , Secuoyan luclear Power Plan:," '/clumes 1 '.3, anc Amendments 1-63.
- e. s.5, Nuclear Reguia: cry Commissien, " Safety Evaluation Recor: Related :
- ne 0:eration Of Sequoyan Nuclear Plan: Uni s 1 and 2," "UREG-0011, Mar:n
.:t:
- 3. J.5. Nuclear Regula ry Commissien, " Safety Evaluation Recor: Rela:ec 0 ne Coeration of Secuoyan Nuclear Plan: units 1 an: 2,* Su: lement Nc. '.,
NURE3-0011, Fecruary 1980.
J. c
'J.S.
or n e"uc,le.ar
. .,.. , .scRegul ei :ent a:
, . cry,,,,3 Commiss,:- - , ion, ",1RC
-a.. a a - :v,.,.ay e a tion Pl an Devel pec as a Resul-
.-,::n.
- 3. . 5. '4uclear Regul a:Ory emmissien, "TM -Rela ec Recuiremen s f:r iaw
- era ;ng ' icenses , ' .iuREG-06sa, June ' 960. .
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