ML19270H566
| ML19270H566 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/27/1978 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19270H563 | List: |
| References | |
| RTR-REGGD-01.083, RTR-REGGD-1.083 NUDOCS 7911110083 | |
| Download: ML19270H566 (7) | |
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_n SIS'pCRTI::G 7"F':C"E';T TO FAC'LITY Cprp.t.TP:q t ICE *::E :3. Cp-M liETrop0!.ITt *: EDIsr*: CC" N P JEp.SEY ciN a :. Pnw ? c3 LNHT CC'M::Y PE":;SYLYi..n ELECT IC CI N Y THPEE '1ILE ISLA':D *:UCLDP GF' oATI! G STATIO!! - U::!T 1 COCi:ET "1 F0-E"9 Introducticn Dy letter dated October 17, 1974 we requested that Matro;'oliten Edison Company ("et Ed) pre::cse technical scecifications governing ste: :
generator tube surveillance at Three Mile Island !!uclear Ganercting Staticn, Unit Me. 1 (T!11-1).
By letter datec !!cve ::er 29,19 'a, "et Ed listed reasons why they believed th:t such technical speci:ications were not required for the sten generators at Thl-1.
In cur lettcr of Septorber 14, 1976, we stated that there W s insufficient icna t.e i,o 0;,cisting exnerience with ne typc cf staca cener.tces in a:e at Ti'I-l to justify caission of a surveillance program and reiterated our request for sub,nission of proposed :cchnical seccifications.
In this letter we also sucplied rrodei technical specificaticas for l'et Ed's use in preparing their submittal.
"et Ed's response tc t:lis request, transmitted by letter of Mcve.ber 12, 1976,',ics not ful'./
responsive to the guidance centained in the mcdai' cechnical specifi-cations we had scoolied.
Accordinoly, by letter cated December la, 1975 we requested that l'et Ed resubmit Orcrosed technical specificttiens for steam generator tube surveillar.cc in full can'crmance ' tith :ne model technical seccifications or orcvide specific justificatien for any deviations from the mcd21.
"et Ed's resubnittal, transe.itted by letter dated Jcouary 7,1977, still uas not in confor cnce i..ith cer:=ic.
irc.porttnt provisicr.s of the codel technical sancificaticos and ac2aca;2 justification for the deviations was not provicea. Therefore, rMi fict:i:r.s to this last prcposed accod. rent were necessary to provida corplianca with our regulator:. positic.n. These redificatians have bcen discus:0 :.
with !'at Ed. The follo.:ing evaluation incorporales the '2C positicn.
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2-Enluaticq Structur?s, systes:s, and :ronents ir ortant 'o safety of a nuclear po. er plant are cc:igned, f 3bricated, constructcd, anti tes :d 50 as to provid2 re;sonable 'a:surwc that t6'e f:cility can be caerated without undue risk to the ':calth and sa'ety of the public.
To continuously me.intain srch as:urance, Grier31 Design Critarica 32 re<iuires trat co penents ".hich are part of the reactor cocicnt cressure boundary be d: signed to cer.i*. scriodic inspe:*.icn and testing Of import;nt areas and features to assess their s'.ructurs.1 ard leartight i n teg ri ty. The steam generat:r tubing is part of the reac*cr ccolant syste:1 pressure bcunacry ar.d is an impurtant ' art of a ma]ce b;rrier anins* fissica creduct releas2 to tbc environment.
It :150 : cts as a barrier accinct staan reisese to the contair.;nt in the event of 3
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loss-of-cociant accident (LCC;).
To act as c.n effective ' arriar, thi:
c tubing trust be free of crack:, perforations, and ceneral detericratior For this reastn, a progre= cf periodic intarvice inspection is being established to assure the continued integrity of the steca generator tubes over the service life of the plant.
Generally, the major elements of the prcposed stea-1 generator tube inservica inspection program for T"i!-l consist of specified:
(a) sample selation, (b) examination :.:ctbocs, (c) inspection intervals, (d) accept;nce criteria, and (e) reporting requirenants.
Each of these ma.ior elem nts of the progra:n is separately evaluated belc..
(a) Samole Selection The proposed sampling scheme is generally patterned af ter Regulatery Guide 1.33, Revisicn 1
'Insarvica Inspcctisn of Pressurized '..'ater Reactor Steam Generatur Tubes."
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there are scme deviations fr:a Reculatory Guide 1.23 that c.e recuire t0 improve the prngm and/or reduce the potential radiation exposure of "ersonnai that must perform the insnections. The principai deviations fron Regulatary Guide 1.83 supplementary sampling rariuire: rents are evaluated belcu:
(i) Regulatory P:sitica C.5.a, "Supolc::entary Sa:mling Pecaire-ments ' rec 0r. rands t!:at i f the ecd 7 current insacction results durinq an inservice inspect.icn indi" t: any tuh:s.ti t:1 previousi, undet c ad imer#cction! n f b, Or c.'ct.t v as:9, aCdi t ;enal stacn gc 1crat. rs, i' any sr.ald be i n act d.
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a sincic tube in cr~ ;,. n:a ener ~ si.r 5 a previcusly Jndat::ted is a r f ec.1 ' r n f - or greacer. al st0an gcneratcrs its the pl: it shculd c3 ins N Ct d-al;h0t,
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to determine the ent et c :ny f.c',c:e +. r:d?tica in :.
stca! qcnera:Or und3r insnectiCn.
If in0 eMpundM i n:.
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indicates :rcre extensive d2fect ccnditic:'s, i.e., a C-2 cm. ':ic1, then expension to the e:her stear cenerator is recui res.
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approach will provice careful stem; ice exp;nsion of irs;;cticn based on the results of successive stcps, t.hile tending to miniinize the exuosure of inscection ?cesonnel result "a from initial positicning of inspection ecuipT.en in a steam generator. This inspection ao::rcach is opcropriate for this fr.cility in 'nich systen characteristics are sucL that both staan cencrators are expectcd to perform in a similar manr er.
(ii) Regulatory Guide 1.83, Revision 1 recuires additional inspections if the initial inspectien results indic te that more than 10:' of the inspectcd tubes have detectable wall penetration of greater thrn ICT or that one ce more tubes inspected have an indication in excess of the plur'i :
limit.
The additional inspecticns require a cc:aalete tu.:e inspection of an additional 3: End, if i ccuired, a third inspecticn of 67, of the tubes. The progccms sat forth 'n the Ti'I-1 Technical Seccificaticas recuire a second innec-tion doubling the nurcber of tubes inspected in tha first.
sample if are tr'an un of the tubes exhibit detec:able penetration m ster ti.tn 200 cc 17 ne more ar2 dcfective tubes. / gain, if mero than 5; of t! : tubes in the se:nd samole sh<f.1 e c:tect.a u penetratirn "reater :aan 2u ar 1% are de/cctive tubes, a third sarnia is rer.uired, agcin dcublina the number of tubes insoecad in '.he sacand sample.' In the first sc-ole, sampling is to concentrate on areas of the tube array where prior ins;t.ctions or experience have indicated po:cntial problers and fui' length treferse of mch insrected tube is reavired.
For a second or third smie, if recuired, tre inse :ticn may be limited to those part' ens of the t.ces in. :n t s.
first sample or t!'e seand sar.pic irc;cated pc;ential problems.
We conclude ths. the requi :en'.s for additional s s_;li m as sa:
forth in the pracc ad Tacc..ica'. S:cci~icati as fcr "J 1 cce substantially cnuivalent to and rcet we int'.n: of
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- 'e (b) E m inatico "cth e The proposed extmination methods include ncndestructive e:mmi-The specified ino:ncds are nation by eddy current testina.
capable of lccating and identifyinn stress corrosion cracks and tube wall thinning from cnemical wastace, mechanical Based on our review of these methods, damage or other causes.
and experience gain 2d usina these methods by the industry, we have concluded that the excmination mcchcds are acceptable.
-(c) instection Intervals Inservice inspections initially will be performad at least onca If twc successive insce: cions ercc:::cassing each 24 month <.
not less &n iS months indicate gcud staam yncrator rcrformar.ca (C-1 results as defined in Sectica 4.19.2 of the technical specifications), the schedule for subscquent inscections ray If., while on a 40 :ronth be increased to nce per 40 cenths.
schedule, definec steam generator tube degradation is observed as defined in Section 4.19.2 of the technical (C-3 results specificaticas), the inspection interval will be reduced to at The proposed inspectica intervals, least once each 20 months.
therefore, are not identical to but are consistcnc with the intent of these reccamended in Regulatory Guide 1.E3 and are acceptabie.
(d) Accentance criteria The principal parameter used to determine whether any cr.e steen generator tube is acceptable for centinued service is the reasured In order to specify what level of imperfec-imperfection depth.
The tion is acceptable, a tube "pluggina limit" is established.
" plugging linit" is defined in the Technical Saecifications as the imperfection decth beyond which the tucc must La removed frem service, because the tube may become defective crior to *ne For TMI-1, the " plugging limit" is next scheduled inspection.
405 of the nominal tube wall thickness.
Met Ed and the 7.C staff have mutually agreed upon this W; plugging limit in the definitions section of the Technical Although no EM! steam generator tube has to Specification.the present time exhibited any wastaga corrosion, this ? lug limit will provide, in the staff's opinion, conscrvative ?rnec-
"et Ed S s tien aaainst wastace corrosion tube decr2 cation.
indicated it may propose a differant oiuggr.g limit in theI future.
a separate review by the staff.
Based on cur review, the acccptance criteria,are sacisSctory.
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(e) recor*irn Pecuirn e nts Regulatory Guida 1.33, Revision 1, requires a licensee to report to the Connission and to await resolution and approval of the proposed remedial action unen the inspection results exceea the limits specified in the Guice.
It also states that additional sampling and more frecuent inspection may be required.
In tne proposed Technical Scecifications, it is clearly stated.; hat additional inspection "et Ed must perform without reporting to the NRC and requires (1) a report within 15 days on the number of tubes plugged in each stram generator following the steam generatcr tube inscection, (2) a ccmplete recort en the inspection within 3 months following cornietion of the inspection, and (2) in the most severe cases describad in the Technical Specifications, prcmpt notifica ica of the NRC together with a written folicwup.
We conclude that the reporting recuirements are reasonable and will facilitate renorting of pertinent infornation without unnecessarily increasing plant downtime. Therafore, they are acceptable.
_T_echnical Socci ficatiens As noted in the introduction of this safety evaluation, there were certain areas where the technical specifications pecposed by "et Ed did not conform to the staff's m0dcl technical sp0cificaticns.
These areas relate to the numbcr of tubes included in the first sample examination during each periodic steam generator inspection and to the ccrrective a:ticn to be taken if sucstantial tuce degradaticn (C-3 condition) is cbserved.
The staff's positten witii regard to the first issue is that the initial sample size should consist, as stated in Regulatory Guide 1.33, ?cvision 1, of at least 33 of the tubes in each steem generator cr, if only cne steam generator is inspected (which is ?crmitted under specificc con-citicns to minimize personnel radiation exposur?), the sarole size in that steam generator should be equal to 35 of the total number of tucts in all steam generators. Under these provisions, ti:e minimum total number of tubes initially excni. led is the sama regarcless of '.hctner all steam generators are inspected or inspecticn is cnncentr$ted on a single staan generator.
The effect of this cravision is that, if conditi:ns permit inspection of only one steam gencratcr, tha ins;;cction is aJt :n.e:
to cc.rpennte for the fact that only one stean e nentor is beim " sa::Ou and tia overall level of surveillance is maintai:.a.
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position, t.; wever, is that if only a sincle stern generator is en 'ircd, the ini'.ici examin' tion r.ced cnccc ass cnly ;. of t".e tub 25 in ; rat st=
generatar.
This represents no arc Ontation or coruenscticn.'Or tne f :t that the other ster.r generr.tcr is not being inspected and therefore erre-sents a substantial decrease in the surveillance samole size.
Since thi, s
does not p evide a level of protection equivalent to the intent of lecu-latory Guiu 1.33, p.evision 1, we find the licensee's proposal in this reyrd unacceptable.
We have, accordingly, followed the staff's positice with regard to this matter in the enclosed technical specifica icns.
With recard to the action to be taken if a C-3 ccndition is cbserved as a result of steam generator ins ections, *.he staff's position is that subsequent to such a determination all uninspec;ea tubes in that ste:n generator should be inspected.
This position is based on the conct.:sion that a substantial increase in the rate of degracation of steau gnerator tubas from on2 inspcction to the ne" (as evidenced by a C-3 concition),
is.ndicative of a substantial change in operating conditions Aich ceuid affect the entire steam generator and therefor 3 Uarrants a corplcte inspecticn of the steam generator.
(Note. Both the staff and the licer.see agree that a C-3 condition in cnc str.nn ger.erator also requires inscacticn of the other steam generatcr(s)). The licensee, on the other hand, Tain-tains that under these conditions the' inspection of an additional IE of
- he tubes-is adequate. The difference bet'.;een the staff and the license 2, therefcre, is a matter of degree.
Because oi the impnrtance of rhe steam gew&i.cr tubes as a T.ajcr particn of the rc:ctor ccolant presn"1 bouncary, hc'.:ever, and because of Ll.e operai.ional signi ficance of the
. occurrence of a C-3 inspection concition, we c0,;clude that under sucn conditicas reasonable assurance of stc;m generator tube integrity car. be provided onlj by a complete inspection of all of the tubes of the aff'.ct1d steam generator (s).
Accqrdingly, we find the licensee'; propes;.1 in *qis regard deficient and therefore unacceptable. We have thus folicwed t*.a staff's position with reprd to this matter in the enclosed technical spcci fications.
In suunary, we have concluded that the orcposed stea"' generator tube inservice inspecticn prcgram, as."Jdified t
- eat our reau recents, r;ill provice added as%rac.ce of the continued in
- grity of tre star generator tu';es, and thm is acceptable.
Enviro n__i_'al Cons 5h'" tie.u Un have determined that the amandment does not notheri:2 a char.p in effluent types or total amounts nor an incranca in ne..er level :ni will not result in any significant environment::i aact-Ibviq~ ~;Ja this detc.~.ination,'.e h:ve fure er conclu ce trat n e v m =nt in.:' m:
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Ccnclusicn E'e have concluded, bued on the considerations discussed above, that:
(1) because the e.-endr9t does not invcive a sicnificant incrone in
.he prcbability er consequencas of accidents priviousiv considered and does not in 'olve 3 significant decrease;in a safety ma'r!)inI!.$$ a and"'n*'~
tha does not involve a significant hazards consideration, (
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reason:b,re assurance that the health and safety of tho n
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be endarTered by operation in the proccsed r~="nner* w" (m
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~.se. in ccmvliance *.c a-ac t i v1 t i n s ii l l te c i'~s rh c ~[iss'^"'
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on defense and security or to the health and safety of to 9 Dated: June 27,1978 709 qq-us.
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