ML20037C063
| ML20037C063 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 12/29/1980 |
| From: | Deyoung R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| Shared Package | |
| ML20037C054 | List: |
| References | |
| NUDOCS 8101210671 | |
| Download: ML20037C063 (30) | |
Text
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UNITED STATES C: AMERICA NUCLEAR REGULATORf COMMISSION 0FFICE:0F INSPECTION AND ENFORCEMENT 1
Victor Stello, Jr., Director In the Matter
)
Vermont Yankee Nuclear Power Corp.
)
Docket No. 50-271 (Vermont Yankee Nuclear Power
)
Station).
)
DIRECTOR'S DECISION UNDER 10 C:R 2.206
- Ms. Virginia Callan'and Mr. Cer
- Ricnarcson, by letter to Cnairman Ahearne da ed November 27, 1980, on behalf cf :ne ".ermon: Yankee Deccomissinning A 'f ance, as well as several otner inciv'O. sis, /.have requested :nat the C mmissier 00ncuct a full and pu:li: investiga-icn inte the cperation and safety cf tne Verment Yankee Nuclear 00*e* :~a-,
na a public hearing be neid on :ne findings of such inves-igati n. a : :nat :ne facili y remain srutdown 2/ until tne requestec investicat':r an: nearincs are complete:.
Ms. Callan and Mr. Richarcson's letter nas :ee-eferre: to the Office cf Inspe::icn and Enforcement for actier pu s.ar
- 10 CFR 2.205 of :ne Com-mission's-Regulations.
Ms. Callan and Mr. Richarcson conten: na recently a numoer of serious and unexpected problems have surface: at t e Vermont Yankee facility.
-1,'Rancelon Wilson of South Royal on, Verme- ; Leslie J. Dowling of Brattleboro, termont; Lisa Licent and others on cenal' cf the Ad ' Hoc Citizens Group for Safety at Vermont Yankee, of Greenfielc, 'tassacnusetts; MacNeil of Greenscoro, Vermont; and Jean V. Lowell of Hollanc,.ermont.
2/As of tne cate of Ms. Callan and Mr. Riccar: son's letter, the Vermont Yankee facility was shutcown for refuelin; and miscellaneous recairs.
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Director s Decision:
2 Their. -letter 's tates that "there will be' a eal 'and imminent threat: tc human :
life $if ~ Vermont _ Yankee reopens." Specifically,: hey allege that cracks anc
~
corrosion =in a sixty-foot section of pipe in tne plant's water cleanup system.
- have recently been discovered; that the fa:ility's turbine generator snowed signs of significant wear and will require recairs; that_the rec'ent replacement-cf a:large number of bolts in the facili y s piping support system raises con-i.
cerns abce; the safe operation of tne faci ~ity; tnat tne Dry Well. Torus emergency c:n ainment system has a history of repeats: and cos-ly failures i.n recair attempts "resulting in years of operation wi nout :ne full benefit of this c-itical safety system"; that Vermon: Yankie is tne only plant in :ne Ocuntry tnat ref_ses te install an inerting syste-sat finally that the t'an has cien aliesed t: cperate since "las: June.
ncut any further a::icn from Verment's ha:er Resources Ecard on :ne 00m:1 s a: plication :: renew its water dis:harge permit.
On Cecem er 15, 1950, the Office Di e: :
anc mem ers of his Staff,' me:
I w' n four representatives, including Ms. Ca" an anc Mr. Richarcscn, 'of tne Vermon ran<ee Decommissioning Alliance in Be:nesca, Maryland to discuss the issues raised in Ms. Callan and Mr. Richar:scn's letter.
A'ter considering the requests, for ne ressens set fortn below, I have con-c'.uced tnat a full and public investigatior into tne issues they raise is no l
warrante: and that the public health and sa'ety does not require tnat tne Vermont ankes' facility remain shutdown 4::crcingly, I nave cetermined not
- : rant the reouested relief.
~
=
i
.4 Dire:ter's Decision 3
I All of the issues which Ms.' Callan an Mr. Richardson = cited in their
~
letter had been identified previously;and _are ceing resolved on a generic basis.
The letter contained no new.information or safety concerns unknown-to
~
the NRC.
The five issues raised by Ms. Ca'lan and Mr. Richardson's letter that are wi:nin NRC jurisdiction are-discussed in cetati celow.
Findings and cctions.taken by the licensee anc the NRC a e accressed.
Tne six:n issue, rega-ding a::icn of the Verment Water Resc. ces Ecarc, coes not lie witr.in tne
-:crview cf ne NRC, anc :nerefore is net a:: esse in this de:ision.
4 React:- bater Cleanus Sys e. Crt:ks a : :s: air Ms. Ca'ian and Mr. Richarcsen's lette Es;es tnat " cracks and corrosion f
have beer dis:cvered in com enents cf tre :lant's wa e Cleanup system inciuci ; a sixty foot sectior, cf :ne.e imper ar. rea: tor water discharge-
- ice."
They contend tna; these cracks a.: : rresio-. ave tne potential for causing a loss of coolant in the sa: cr that woulc result in immediate danger to tne public.
Ine rea: tor water cleanup (RWCU) system ins alled at tne Vermont Yankee (VY) plant is not a nuclear safety relate: system.
It functions neit7er te provice cooling for the reacter.00 s ner to mitigate the consecuences c' any cf the analy:ed acticents cons':5 e: in tne fa:ility cesign.
The
Director's Decision 4
design fun: tion of the RWCU system is to provice purification (cleaning) of. reacter water, which is acccmplished by continuously removing a portion of the reactor water and processing it through~ filter demineralizer units
.to'uncergo mechanical filtration'anc ion excnange processes.
Except for
~
an approximate 60 foot length of piping and two associated valves' located insice.tne drywell containment, all c:ner RWCU system piping and components are locatec outside :ne crywell anc are sucject to routine visual surveil-lan:e curing plant operation.
The visual surveillance, together with lea < age conitoring instrumentation, prevics_ assurant: cf early~cetection 4
cf a lea. sncuid cre cc:ur.- Tne RW:L' syste-. piping inside tne crywell provides t,e tap-cff cin frem whi:n rea::cr ccclar water is taken tc be peccessed.
Inis pi;#ng an: asso:ia e: isolation valves are a part cf the rea::cr cocian system pressure c:uncary.
Inis pertion of RWCL piping. Elen; with all other pi:ing ' sice the crywell, is suyject to centinue;s monitoring ty leakage cete::icr inst umentation.
(Limitec at:ess :: :ne crywell prohibits rcutins isual surveillance cf RWOU piping ;-ing normal plant operations.) Tne crywei' leakaga monitoring systems :r: vide assurance of leak identification at an -early stage so tna; prc:er ccrrective actions can be tagen well.oefore leakage oe:cmes sufficie. to compromise the reactor ecclant barrier integrity.
A furtner coint snould be made to bring in 0 perspe:tive the problem cf cracking-in RWCU system piping.
One coulc postulate, in spite of assurance of leakage cetecti:n capability Orct':ec Oy routine surveillance and leakage monitoring systems, tna a ecc lete break (severance) occurs in
e Director's: Decision-
.5 the 4 in:h diameter.RWCU piping insice :ne crywell.
The emergency core.
. cooling systems ~(ECCS) installed at the VY :lant are capable of providing adequate ' core cooling and protection for a spectrum of pipe break sizes, up to and including the break of a 28 inch diameter recirculation. system pipe.
The complete loss of a 4 inch ciameter RWCU system pipe is well' within the capability cf and protectica a'ferded by the ECCS and thus, ne canger to the health and safety-of tne ru:li: snould cccur.
Notwithstanc'ng the above, :ne integri:;. :' :ne RWCU system, along witn all otne piping attacned di e::1y :: :ne sactor ecciant system, is of im:crtar.:e.
Tc provide addi icnal ass;-a :s cf piping integrity, er
- enversel). : provide assurance na: :e; 1:stion o' cipinc integrity is identi#'s: well befcre sigrificar.: lea <a;t ::cic cevelop, all reacter to:iant system pressure boundary pitir; 'rs'Oe ne crywell,-including RWCU system picing, is subje : to insem i:e inspection (ISI).
The ISI crocram is performec in accordance wi:. ' :;stry :cces and standards.
Or Vercer.: Yankee the governing C ce 's :7e American Society cf Me:nani:a; Engineers Eoiler and Pressure vesse'. C::e. 1:-74 Ecition,Section XI Rules for Inservice Inspection of Nuclear P:we- :' ant C =penents. This previces a systematic means of inspecting react:r :::lant system piping. -Insce:-
tiens cencutted uncer the ISI program em:ic;. techniques, such as radiograpny and ultrasonic examination, ca:able Of ce:e::ing cipe Oracks at the incipient stage of development, well tef 0 e they eculd be cetecte: by l
visual ceservation witn the unaice: eye.
-re ISI progra schedule is
n 1
J.
.~ D Dire: tor's Decision 5
-1 established such that all rea::cr c:c'ar system piping ~is-inspected within -a ten year -interval ~
The ten year interval is then divided inte tnree inspection periods, with inspec.icns conducted yearly within east period, usually during ar annual re'usiin; cutage.
Development and implementation of an ISI program, as-.eil as repor-ing the results there-from, are a condition cf tne VY license :: Operate.
Implementation of the ISI. program at VY is.rcu-inely ins:e: e: by *he NR 's Office of
,nspection an, :,n,.orcement, n.egion..
ns nspe::icas include a t.,.orougr review cf the ISI :r:grar an: prece:u es. ei:nessing of a portion cf :ne
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Tne lates: series of NR:
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ine ISI prograr insce:-ions :encu::e: :.
curing :ne 95: refuelinc
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50.55a of :ne Commission's reculati:ns.
I.-ing this inspection, VY
- ers nnel icentified cracks in seve a' -e':s i::sted ir. a 50 f0ct se :ic-g g.
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.5 1 r.1 ti a l Inspe :icn i1D ings NhL were reported to tne NRC in ac rcar:t
.# r licensee recuiremen s (see VC 3,1:ensee event report, L.....-.ic:n:ecite -o,
.ontinue: inspection er. the subject piping over a two week perie:.':' ately revealec six welds with
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etner cuta;e maintenance work an: c'-'ma e j extended the length o' the
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re:ent cu age oey n the senedule: :: :'et'On dat=.
NRC Region I IS: Spe:ialists were ens':e f:r tne routine inspection cf tne IS: Orogram wner the RWOU systa. : racks were first icentified :y tne-licensee.
(Had the Regional insce:t: s not :een ensite, a special insce: tion woulc have been condu: e: as a esult of the finding cf cracks
~~ Di rector's [Decis' ion '
S-in the RWCU system.)- In addition to :ompleting a review ef. the routine.
- program, tne Regional. inspectors closely followed developments in the -
RWCU crack problem.
The review-incluced:
independent evaluation of. weic-radiographs, review of-the bases for additional welc inspections._once the-initial defects were found, and review of the piping replacement prograt,
' including procedures and techniques used, quality controls appliec, anc inspection of activities in progress.
Insaettion-'of the area by_ Regional Specialists was concu::ec over four. separate _ special inspection-trips cf one week each during the period froc' September 29 te November 21, 1930.
Witn'r ns scope of the areas reviewe:, ne noncompliances or cevia-icns frc in us: y coces er NRC regulations wers icentified.
It shoul: a's:
- s n::ed na-VY management cevelcpe: ant :aintained tne -initiative
'n-se'.e::ing :ne proper alternatives for : r e :ive actions througnout.:na tevelopmen Of tne R4:U crack pro:lem.
NRC Staff ::::ar:: -.e VY ISI fincings to the criteria ~ es ablisne:
NURE3-C312, Rev. 1, Tecnnical Reacr: :- Ma erial Seie : ion anc
- -ecessin; Guidelines 10- BWR Cociant Oressure Bounca v Dicin;, cated Cc
- c er, 1975.
NURE2-0313 summarizes One NRC Staff fincings anc con:iu-cions regarding the : urrence of inta grannular stress corrosion cracki g (IG5CO) in 5WR pipi.; sys ems, and presents methocs acceptacle to :ns 5 aff for -epair of ci:e cracks.
Upor co::arison with :ne NUREG-03~_3 criteria, ne staff consicers the m)s-li<ely cause of the VY RWOU sjste-pipe cra:ss~ c be I25::, in :nat:
(7.' :ne facters ne: essa y :: caust
' Director's Decision 9
Final confirmation of the pipe crack mechanism will be obtained once the metallurgical analysis results from samples of the affectec welds are available.
The licensee will report-the analysis. results to the NR Staff for review.
In accordance
~
witn NUREG-0313, one repair plan acceptable to the Staff consists of replacing existing service-sensitive ;1 ping with corrosien-resistant ciping whose material ~ constituents are contrelied.within specified lici s.
VY management-informed the NR: staff 'n a ie:ter dated Novem3er 10, IEEC tnat the RWCU repair would :s 0moleted witn material conforming Ic
.or:e-,::::, n ei, _.
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istter c VY cated Decemoer 12, 1930.
4 As a result of the ecmpletica Of RWCU system repairs y VY in :ne manner ces:rited acave, the RW:U syster pipi g is excette ;c os i conferran:e
.":n apoli:acis reguia:Ory -ecuiremen s an: incustry 00:es.
A::ual re: airs were 00mplete as of 12.'17/SO.
Sa-isfactory ecmpie:f:n o' Vi actions in tnis area is being verifie: cy tne NRC inspectict staff as par: c' :ne routine inspe:: ion program.
In sum, the pre:lem of cracks in Verm:n Yankee's RWCU piping syster raisec ey Ms. Callan and Mr. Richards:n nas already been accressed ty - e licensee an: ne NRC.
The pi:in; system nas seen reciacec ey the 1::ecsee e
l Director's' Decision
'10~
~ and will be reviewed by NRC inspectors. LInLaddition,theRWCUpiping-
. system nas'been, and will continue to be,: sucject to continuous monitoring.
.and-inspection.for leaks.
Finally, even in tne event c'f a complete break
.in the RWCU system' piping,.the ECCS would afford adequate cooling of the.
reactor core.
.In view of the preceding, I conclude :na: accitional "ful.l and.public investigation" in*c'the problem of.cra:ks.'anc corrosion in Vermont' Yankee s i
RW U pipin; system is'not warranted.
Irladdi-ica, Verman Yankee's actions wi n respect to the RW"U systen are-in confermance witn its license and thus, in the absence of s::e safe y issue,fa basis.does not
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Dire: tor's Decision.
11 Durin: -he 19SO refueling cutac.e. Verten: Yankee perfor id inspe:-ion cf -
sele::ec ortions of.the turbine cenerator uni in accor:ance wi n rout 1ce r schedsled maintenance and in creer te establisn a da a base on turoine condition.
In this regard, Information Notice (IN) 79-37,.Crackinc in Low Pressure Turbine Discs (12/31/79),- was forwarded te Vermont tankee provi:inc notification of a pcssibly significant matter in taa escecced
. s cra:< ne. in ke.vwa.ys anc.
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Director'sL0ecision 12 actually " bows" due te its weight and : es netLin all cases provice a flat bearing surface ~.
Inspection of he. 6 bearing by the licensee revealed
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uneven Lear.' The bearing was sent to a con ra: tor for.macnining to proviae for proper rotor seating.
The b' earing was subsequently reinstalled.
Tursine erosion (water wea-)
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thermal enercv-conten of the steam is tra.sferred tc tne turoine as rotationa. ene-c..v and in:reasin: ra:-
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.e.
Cirector's; Decision.
L13
.this, IGE: forecast conditions six: years c' operation' later.
Using con-servative (rapid)'growtn rates anc Oceparing tnese'6 year laterl depths with.the " critical" cepth at wnich' concern would arise 'for rapid 'ailure, GE predicted that _the erosion at the most critical location would be about 37% of allowable depth.
GE recommended tnat tne licensee condu::.another' inspection of the water wear in the' turbine wheel keyways i-5 yea's.
Verment-Yankee now plans r
to inspe: ;the high pressure turbine 'n 1992, one low pressure turcine in 1923, anc ne other low pressure tur:ine in 193.
C:her areas wners wa er er steam ercs':r were fcune inciuced 's:ca.-heace 5.
crossover pipin; ar.d ths low pressure u :ine inner:asin;.
where ::.e depth-cf ercsion caused the minimum wa'l tnickness :: se apprea:ned,.wa
thickness was restored :y welc me al : -' cup.
Inis is a weli estatiisne:
and acce:ted methoc cf repair.
Verm : fankee de:icet na: future er:sicr could De' better contr: lied oy a _cnange in ne-material f the crossover piping from a ecpper cearing material
- a nickel bearing material. -Tw:
cf the : ices were repia:ec curing the :urren outage, and the other tw:
are scheduled for re;iacement during :ne 1951 outage.
Inspection of turbine discs and blacin; revealed a cracke: clade in :ne eighth stage of the A-low pressure tur:ine.
The blace was remove. anc a blade on :ne cc:: site side was shifte: to maintain symme: y and balan:e.
j l
l J
l
m L0irector's Decision
'14 The licensee concleced that this crack represented an isolated, random occurrence and was not a precursor 'of other failures.
In summary, I find that Vermont Yankee-has responced properly and conserva-tively to concerns expressed by the NRC-in IN 79-37, and to the results-of other planned turcine' inspections. -Therefore I find that there is nc basis fer conducting an extensive public investigation and hearing en the subject of turbine integrity.
3.
Anc.,c-501: Replacement Ms. Callan and Mr. R':narcson's ie::e aisc alleged tha a large numcer of ::cits i :ns fa:i'i y's picing sup: r. systet r.a: re:ently :een repia:ec and :nat sucr repla:sment raisec se-i::s g.esticas concerning tne safe-cperati n Of :ne pla.:.
Wnile perferr'n; ro ::ine inservice insce:.icns at the Milistone cri: _
powe p'.an; in Water Ord, Connecticut curing the 5 ring 197E ref es'ing outage, ne -lant :e sennel icentifie: stru:: ural failures Of picing sup:o-ts insta', led c.
safety relatec systecs.
Su:secuen: licensee insce:-
ti:ns cf undamac.ed s.:c. orts showed a larc.e c. ercentac.e of concrete ancher belts asse iated wit-the su;; ports that were not tigntened prc:e-iy.
Tnese findings were re:cr.ec to tne N;;.
Sucsecuen.ly, tne licensee Of ine Snerena,T. oower ::an. on Long Is'.a.:. New York rescr:e: cefi:#encies
Director's Decision
'15
=it had identified concerning the design c' base plates used. in piping
~
system supports..The deficiencies involved rigid plate assumptions used.
in the design of. anchor bolt installations.
Further NRC review at Architect Engineering (A/E) firms (the organizations principally involved in _ anchor bolt design and installation) showed a wide range-of design practices and installation procedures used in concrete anchor bolt installations.
The NRC determined that current trends in the industry are to employ more r'gorous con rcis and bolt installation verifications tnan had been a:clied previously.
I recognition of the safety significance anc potential generic a:plic-a:ility cf tnis information, ns NRC issue: !E Bulletin 79-02 on March 6, 1975 to estaclisn the NRC's 'indings 'r ne area anc re:uire :na; certain actions be taken :c cetermin~e :ne sta us c' anchor belt installations at-a'l power :lants.
As further infctmatier was receivec :y tne NR: from l'censee responses to tne Bulletin, su:clements to Bulle-in 73-C2 were i
l j.
issuec (Revision 1 on June 21, 1979 an: Revision 2 on Novecce-E, 1979) tc clarify certain requirements and te direct that acditionai actions be taken.
The majer work effert associated with Sulletin 79-02 ceveloped along two paths:
(1) test and qualify or replace ancher b:lts installed on plant safety related systems te assure original cesign requirements were met; anc 1
1 l
-1
" Director's Decision 16 1
(2) fre-evaluate certain assumptions use: in the seismic analyses to define piping ~and supper; system cesign. loads.
Issues related 1a) tne seismic design analyses developed during the 1978-1979 period and led to tne issuance of furtner. Bulletins by the NRC (IE Bulletins 79-04, 79-07,. and 79-14).
NRC staff effer s were consolidated to review L
the anchor bolt an: seismic issues togetner in 1979.
L I
- Vermont Yankee ceveloped a testing an analysis program to adcress NRC I
Sulistin :requiremen s en seismic anc an:nt ocit issues.
Tne program to o
ve-ify tne acecuacy cf installe: an:n: ::' s egan in mi -1979.
After icentifyin; ne ypss anc 10:ations c' su::e-ts on all seismic piping i
F sys ems, cefining suita:le cesign a::e::an:e criteria, and ceveleping test anc inspe::icr. prc:ecures, esting O' ins allec an:nor colts at i
l Ve rman: Yanxes :ega. in July,1979.
7esting consisted Of torquing er load tensioning :ns an:ncr acits s:e:i'ie: 'imits tc cete mine.wnetne*
tne belts coci maintain pres riced ica:s.
Tne installation of ea:n anchor bolt was als: inspe::e: anc co are: :: stringently cefined installation cri eria :nat incluced de;:n f enaeccents, ic:a-ics an:
length, dimensions, nreat engagement an: va-i:us ga; distances and l
clearances. Testing of bolts negan in areas in tne plant reacily r
l accessible curing normal plan: operations an: Ocntinued for all plan:
areas during :ne 1979 refueling outage.
i l
Director's De:ision U
Ecit testing com lete: e.v mid-Auc.ust '??9~ revealed instances of. failure to mee. testing anc inspection criteria at. a rate in excess of pre-esta:lishe:
limits. ' A-small. percentage-(5%) of tne b:1 s tested were found icese,.
but coulc be tensioned to above desig-'icacs.
However, it was noted that for the "as found" ins allation,.a-larger cer entage of the bolts failed
~
one cr more of-the e.ner inspection c-ite-ia.
Inspection of the support instal'.ations continue:, but testing was s p ed. 'Insteac, a program was bec.un c recla:s all slide t. vee an:ncr :c' s.ith bolts of'an im:reved e
d a. c i v.
- a..d.
.c -.. c- - *. i n s *.c-l i a.i ^
e - 4 2...-'. e s.
- v 0-.ober, '.c'/.
- .he 0
s:cpe c' :ne re:lacemen. prograr.reve..a: :een rerined te include,,:.0
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- v '.he end. '.
.7 a. ' : 7. 0 ra.-
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- a. - - -.. c.e.c a..- c '. i 2 ~.. ^.. s
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- a.. c- +.....c.
A '. ' c..., -. bal..e w a.. c.
- =.. l a. a.c c 1.
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..=. e.... n..", o
^
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~.. =..
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inspe:. Ors reviewec
..'s development c' tr.e ir.itial test /ir.sce:.ior program.
d e v a. l -....a. n t.
o '...l e. - i.. *. a. p '. a.- c.r. a.,-. :..-=..,
- e. 'v'.
ie.c. '. w. *. k ' r. ". rc -. =..e c..
2 anc co :'ete: b:lt installations.
- n2 itsnti'ied installation de'iciencies i
+ ". e-. n c-. *1e ac.en.'.='.
.a i t..' a..
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3 s.yster were ccrre::e: exced:.:1 ous t.v.
. s a :es e,, inis t.v:e were s:ec:- ca r
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1
- Director's D^ci,sion:
18 reported to-the NRC cy the submission of: licensee event' reports.
In no
~^
case dic-a loss of system operability occur.
NRC inspection'of the licensee's'_bc1t inspection and ' test results icentifiec
- only a_ few instances' (less than 6) in which a bolt nead was tack welded
- to a base plate with the bolt shant' cut off or missing.
Deficiencies.of i-tnis tyce-involved one colt out cf several installed in any given size succort.
All,other ceficiencies invcivec ceviations from bolt installation criteria er ceviation from a specification. -Some ceficienciesialso inv:lvec roken o-ca iagec bcits.
r :: rs contrice:ing : tnese ceficientiss a
coul nave includec (out are not l'-i e: tc): inacecuate cuali y con:rcis ampliec caring criginal sup or:/oc'- 'nstailation; less stringent crite-ia
~
l cefined fer initial installation wner ::msared t.: tne cri.eria in curren r
I indus.ry standarcs; difficul y in Oe-ferming the initial installa:icn cue. onysical constrain.s (su:n as su:: Ort loca.icn anc/cr limitec i
accessibili y); worker carelessness; a,c insufficient cesign.
ll m,
l
. ~.
NRC review cf the com:letec an:nor oc': installations, as we :', as '.ne l
i seismic ana!.vsis proc. ram,.is onc.ein:.hrouc.n the reu.ine inscetticr
\\,
i
~s program.
'w j,
/
a Ine ecmpany cirectly invpived witn
.r.s initial an:ncr bol:~ instaliatien
~
wastheHartwellCF.,'$bdercontra:::: EbafE,o7:neArchite'c:/Encineer
~
' -e q
(A/E) for initial piah: constructic.
Under cyh r:t n.
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. Director's: Decision 19 Hartwell was responsible for "furnisnin; material, fabricating and erecting the complete power _ plan piping. syste, including related hangers' and -
supports." Ms. Callan and Mr. Richarcsor raised concerns _ questioning the -
adequacy of other work conducted ~ by _tr.is -company.
These~ concerns are net warranted for.tne following reasons:
-NR: inspections' du-ing the plant ::nstruction period, wnile done uncer a sampling program, snowed ' h a:high degree of confiden:e that no major breakcown in the ::ns ruction QA/QC area 00:urrec. !r.
sarticular, no maj r QA/Q: crc:is s were icentified in egarc ::
rea: c Oo:lant pressure :cunda ; ancor safety system ci:ing insta'la-tiens.
Tests conca::ed ur.:er ne Te:nri:a' 5:ecification survei' ance progran en olan-safety systems i.e :emonstra:ec syste :nera: 3 (anc nence pioing inte;-i >) un:5 :: r norma:~operati ; anc trar.sien condi:icns.
Tests conce:ted unce ne Inse v':e :nspection program ave _ n: -
identified ceficier.cies tna wcu': :s attributa:le to imp oper construction QA/QC.
Ir. summary, altacugh de'icient instal'a ' ens nave been icent'fied ir. :ne use of pice sup:c-: anc..or'bcl s, tre :e " :iencies have Deer *e::i'is:.
w
. s.
Director's' Decision L20-i I
. Pas NRC inspection findings in -the' area Of piping anc support installa -
~.
tions do not, support. contentions of generic fraudulent installation s
practices anc. concerns.of present opera-ion in a degraded safety condition.
Consecuently, I have cetermined that furtner investication into'the bol:
.reclacement problem is not warranted an: :nat there is insufficient cause to, prevent the VY plant from resuming'p:wer operation.
4 Torus Mo:ifications Ms. :atian and Mr. Rienarcson allege na :nere have been re;satec #a'lu es in a tem:-t :: repair Vermont Yankee's :,,.~eil Torus energency con a n. en-d syste an: -ha :ne sys em is again u :e ;:'n; repai.
Ms. Caliar an:
l Mr. F.icnarcson con end tna :nese pro:lems 'n rease the Enge cf a I
li'e-n eatening a::icent at the 'a:i ; 5 #r. e the ;orus ~ sys em was E
LA cesigne: 0; serve as a back up :: tne :'a-s Orimar.v toolin:. s. s e '.
y i-
-he even
- a loss of coolan a::ide-.
l t
Ve-mon: Yankee utili:es a Mark : or ":. ~el' orus" pr'.ary ::ntai -=.--
design.
Tne Mark l design is a press. e 3.00 ession type an: is sa:e u:
of a drywell in tne shace of an inver e: 'ign bulo connects: via ve--
pices :: a Orus snapec suppression p::'.
The obje::ives cf ne pr' a ;.
containment system are, in the event :' a design basis loss- ' cccla ;
i a :icen (LOCA), to prevent :ne release :f 'ission procu: s : the en.' : -
e 1
...,..4,.
, X.. e.e c,.n.
e=Ca..e's 1 3...1 +..: :...e#2 c. - 4.n 7..
-:: :=,.-....
1 w
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l 1-a t
O Q
-Director's' Decision 21-provide pressure'~ suppression,.and to :r:vice a source of water to certain Emergency Core Cooling Systems-(ECCS).
The suppression chamber is a steel pressure vessel in the shape of a torus, ' located below and encircling tne drywell-The suppresssion chamber is-held on supports which transmit ve-f eal and seismic loading to the reinforced concrete foundation slab'c' :ne reactor building.
Eignt ci cular~ vent pi:es connect the crywell and the suppression :hamser.
The pressure suporession chamber serves n:t 'only as a heat sink for blowdown
~
fr:m the drywell after an accicen bu also as a source of wate or hea; sink for ne fcliowing ECC5 fun:: ions:
1.
Core spray injection anc testing.
2.
Low pressure :colant inje:-ion m::s cf residual heat removal (RHR) and testin;.
3.
Hign pressure coolant inje:-ion fi:::) and reactor : ore isc'a-ion ecoling (RCIC) pumes alterr. ate s:
- e of water.
4 Heat sink fo steam blow cw-fror s a'ety/relie' valves.
5.
Heat sink for HPCI anc R::: tur:ine exnaust steam.
The first generation of General Elect-i: (3E) BWR nuclear steam sup;iy systems are housec in a Mark : contai.me-system.
A total of 25 EWR fa:ilities with ne Mark I conta'nment system nave been or are being built in the United States; of :nese, 22 are li:enske for power operation.
The original cesign of the Mark : conta#r. ment system consioere: pest ia e:
a::icent loads :reviously associate: -i-
- ntainmen cesign Sin:e :ne
-Director's Decision 22 establishment cf the original design criteria, additional loading condi-
. fons have been-icentified which arise in the functioning of the pressure
-suppression concept utilized in the Mark I containment-system design.
These additional loads result from the dynamic effects of drywell air.and!
steam being rapidly forced into the suppression pool (torus) during a costulated LOCA and from suppression pool response to safety / relief valve (SRV) operation generally associated witn plant transient cperating conditions.
Because these 1cacs had ac.'ceen considered in.ne original-cesign cf :he Mark I containment, tne NRC cetermined that a detailed eevalua.icn of the Mark I containmen; sy! em was recuired.
- r ecreary and A:rii,1975 the NRC tra s-i.tec ie ers to all u-ili-ies cwning...,a::.....1 les witn h,arn,i con.alnment system ces1gns requesting
- a.. i ne owne-s te cuan-ify the hycrocynami:.icats and to assess the effs:: c' nese lea:s en :ne containment s.ru::ure.
The utilities for e: a Mark I ceners grcup an u:.as designate: as.ne ercup,s lea:. tecnni:al crgan':a-
- icn.
Tne obje::ises of tne Group were
- cetermine -he significance of tne loacs and icentify courses of actie needed :c resc1ve any cu s.andin; safety c:ncerns. Tne task was cividec int: two programs, tne snor. erm p ogram (STP) and long-term program (LT:).
Tne obje::ives of -he STP were te verify that each c'.ne Marg I centain..er-sjstems wculd m=in:ain its integrity an functionai capa:ili y when sdjected to a pes.ulated design basis.- A. an: :c ver"y.na l#:ense:
-Director's Decision 23 Mark I BWR facilities.could continue :: coe-ate safely without endangering
-the health and safety of the public, while a comprehensive LTP was conductec.
The STP acceptance criterion (a safety-te-failure factor of 2) was used
- to justify continued cperation of each plant.
The NRC concluded in NUREG-0408 that a sufficient margin of safe y had.been demonstrated to assure the-functional performance of -he containment and, therefore, nc~
undue -isk to the neal-h and safety cf :ns public existed at Verment f
Yankee.
Subsecuently, tne staff gran ec ne operating Mark I facilities exem:-ions relative to the s ru:: ural f ac cr of safety requirements of 10 l
CFR50.55(a).
Tness-exemptior.s were ;rar.:s: for an interim periot wnils the : m:-shensive '.TL was being ::ndu::ec.
1 Ine li:ensee commi-ac c a 1:n; e : :
- ram to upgrace the Mark I crus '
<r. c.
..z,.
.c..
3, s.:.........
- .t
.v
.,2..or s..
n
.;m=.
.i. tn,.,,:.
.as,.:.
o
..i L
cpe a:s witneu tne full cenefi cf : 's sys em.
l f
In Julj cf 1975, Vermon-Yankee ::mme :e: :dification c' :ne t:rus sup;0rt column t0 tcrus shell Ocnnect' Ors as part of ths "TD 'c st*eng nen the :0 nections.
Since tne modif#ca-'Or.s were'being pe-f0rmec nils -he plant was in coeration, ;ne atta:nmen cf gussets to the cuter snell require: welding in areas wnere tne ::*us snell hat wate" on the ep: site side.
A special wel: procedure was cseel::sc and cualified.
As a 2 e:au-tion, nOndestru:*ive examinations (NDE) Wsas performed curing weleir.; *f NJE reveale: su.-face cra:<- i tre case me*a' a#:er :ns ;usss:s the Oa:s.
i h.
I
I b
2 1
-i Dire:ter's'Cecision 24
.hac :=en partially er :: pletely sel:sd te tne pads.
The licensee cevelcpec:
- a. plan.cf action to shu-down the piat, repair the areas of concern and.
- condu:: a pneumati: test of the torus prior to returning'to power.-
Durin: the October 1 70 refuelin.c cutsce the following werk was performed in :en, unction with :ne L.P:
s 2: cepressions resulting from inci:ations in~ the torus wall that had
- een grcunc out we s repaired.
il aeld me al pacs were welded :: :.e rus shell.
.. g;sse s were we.::e: :: ne a:s.
n.. < e...., c. 3...:-
4=,. <., c. 't. n 3 o".c e...:. '..'i'i.w.n~ woTN 3
i.3
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ow
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- .h e
.0 ". u.C C.e ' l. a s. 2...* l }-
... i an0 reduce i s "eipOnse to cy..aE : :Or.0ensation loa:s.
The sa dles 1
c..... c.. e. 4........., t 4. e.. j oc..e
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2
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Director's Decision
They are.cesigned to reduce the load on the vent header produced by pool swell uplift.
S.
Installation of Downcomer Ties.
Sections of pipe connected to
- lames at eitner end were weice: to tne down:omers.
This design preven s the ocwn:cmers from cefie::ing radially.
Modi #ication of RHR. Return Line Rercute and Support in Torus. ~ Inis-medi'i:ation results ir the Dici g running closer to the rin; gireer wre e it is su:: cried.
An el ow was ad:ed.t promote cetter thermal mixi9g cf :ne RHR retu n water w'
- re peel.
Repla:ement of 2" Safe y Relief.aive 2iscnarge Line (SRVDL) Vacuu-Breakers with 10" vacuum creakers.
Tnese allow equalizing of tne SRV:L-Drywei; ; essure withcut e c: urrence of a hig.* wa:e-ie; '-
the line.
Re:la:ement of we:well-crywell vi:uum creaker cast aluminum cis:
assem:ly with a wrougn; aluminum dis: assembly. This mitigates damage to the cisc during the h gging pnase of a steam clow 0wn.-
Reinforcement cf 4" tores spray eace supper:.
A ;iate was weicec tc :ne existing support :: re:_:e tne dispiacement cf nc 1
1 pipe caused by cool swell upi- lea:1.
l
e g.:
p/, ' '
5
/
LCirector's'Decisicn' 2i Modifications to Submerged Pipir; %.: I anc F.CIC c.Mansate ~ returns,
' P.CIO Turoine Exnaust) to reduce 'm:act 'a crag loads.
Modification tc torus catsaik tc facilitate removal during power cperations.
.,ne acove med1,.ications.have o..een per ::1:a.c. r.:nitored by :ne b....
n.
nes,. cent and x.egion cased inspec. ors.
s ;1:ensee has comp. ted..neL, 3 le u
modifida.' ens that snould restere tr.e :-i;i a' 70rus safety-to-fatiure-
- z. c....
1.: c,. n,,.,.
.n.,
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pr vicc.e 4.-.
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t-L Ir. summa c, I find na: the continuir; '.:: an: 'ncustry revie anc a.alysis L
cf.ne' various safety features of po*s-sa::: s disclosed na; certain L.-
1 desig criteria for the BWF, Mark I cc-a' Te.: system did no contain :ne j
degree cf conservatism originally expi: e.
- furtner finc. hat GE, :ne t
con ainment system designer, and the....cer. sees with Mark. cen.atnment s.ystems, workin=- tec.e.her have ced::s: :- a :e eric basis-c: re:.ive l
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i l
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s
Director's Decision 27 actions which, when im:lemented, wil' res ore tne degree of conserva-ism
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- originallyLexpected. -Vermont. Yankee asicuring.the:re:ent plant outage completed those corrections applicable c its facility.
Further, I find
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'that the licensee is :ccmmitted to su ri, on a: timely basis, a plant specific' analysis whien will confirm -he acecua:y of modifications made to date; or describe such supplementa y mocifications as may oe recuired.
Therefore, I find that there is'n: : asis fer :encuc-ing an exiensive
.:utlic investigation and heari g er r.e s.:Je: of con ainment system' n
in egrity.
5.
Ir.arting of Containmen.
Ms. Callan and Mr. Ricnardson als: as;e - a-Vermon: Yankee -is the eni;.
fa:ility in the country tna: c:ss n:-.sve ar 'ns allec inerting sys e.T Ms Callan and M. Ricnarcson c:nte : - :s "this safety unit woulc fores a91 a ny:rogen explosion tna woul: : ea:-
ns rea: cr con ainment. in :ne event of an accicent."
Iner-ing is not required for :ne Ve- :n tankee plant by a ruling of :ne Ap:eil Scard [ALA5-225, Septecoer 15. ~572; E ABC c25, 425 (1574)].
On 00:ccer 2, 1980, the Commission pu:lisne: in :ne Federal Register a preposed rule entitled " Interim Requi e e..ts Related te Hycrogen. Control and Certain Degraded Cere Censice a-': 3 ' (15 'R 65466).
Tnis rule wouic
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d
__.__u..
i t-e-
u, w Director's De:ision-2-
w recuire ne.Vermon: Yankee plan Ic '96 : sometime after rulemaking--is
' compl e te'd.
The inerting would :e re: ' ed as an interim measure while
-long term rulemaking en degraced cr_ cs;;ed cores proceeds.
Tne propose:
rule states that:
"While One cecrease in residual risk :.s -d inerting tnese containments is. smali,- as -determined oy presa:ilis-': analyses, (a) there are ne sicnifi: ant countervailinW sa'e y cis' :s..tives - (b' ne ecs: cf inertinc.
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is smail; and (c) :nere nas bee-su:s a--fil sa-isfactory excerience wi-h
,4,.....i.,- v.. =. k T.
- -.*..= i nm a. r...c. '-
Rscui-i ;.~erman tankee :: ire - '- 5: stil w:uld :e.very cestly ce:ause i-woui su:stantially extenc - s cs!5 ; :u age in 0 ce-to add equipmen-nc-incl. sc in the present ess'g.
+'i' re :ne preocsed rule-coes ac-call fc ' meciate inerting.
I
-i n e b..... rega cs the cperation c' ne
.t- :.- fangee p.; a r.: w-n ceinerte:
containmen as ac:eptacle pencir; ccc:'i ' r. of the ruiemakin; prccess.
Censecuently, an investigatice 'n c : * # erting issue is not warran e and ne tasis exists that wouic ecui i s.'enting the Vermon: Yankee facility from resuming pcwer cpe a ic-T-
Based er the foregoing, ! have ceterr' e: nat conduct of tne ecuestec additienal -investigation at Vermen-Tankee is ::: aar antec anc.:.;d ne
S.
e s b.
Director's' Decision'
'29 i
I serve'to enhance safety based on the'hign :ssC c' NRC inspection effort that
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nas-already been expended over several yea s e. the issucs raised by Ms. Callan and Mr. Richardson.
In addition, because :ners were no unexpected problems identified' during the current outage at Vermor.t -Yankee, because tne -licensee
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was responsibly adcressing previously icentifie: NRC concerns, because the
, licensee's corrective action toward resciu icr c' :nese concerns is acceptacle to the NRC, and because there is reasona:is assu ants tnat Vermon: Yankee can continue to opera e without undue risk t: ne :c:ii: hesitn'and safety,-I nave determined that no basis exists that wout: :.' e tne facility to' remain snut:cwn.
Consecuently, I have cenie: Mr. :aa an-Mr. Ricnar son's requests for a fu:1 and Oc:lic investigation in e - e si's ::eratfor of tne Vermon:
Yankee f acility an fc continued snut:: - :' - e fa:i i y unti ne investiga-tien is tem lete.
Ms. Callan anc Mr. Ricnarcson nave aisc s:.er 5: a nearing en :ne findings c' an investiga:icn into the issues they na.e a'ss:.
uncer _C C R C.206, M.;.
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Callan anc Mr. Richardsen are not entitle: : a nea-ing as a matter of rign:.
I would view tneir request for a hearing as :ns :na asks :ne Commission te exercise its authority to gran; a discreti: ar nearing.
Se:ause I have denied Ms. Callan anc Mr. Richardson's rec.es: 'Or an investigation into One issues they raise, I would not re:0mmend - a: ;r.e Commissicn grant a discre-tionary hearing to Ms. Callan and Mr. Ricnar:s:n.
J
e,.
eo.o s
Director's Decision-30.
A copy of this decisicn will'be place: i-se Commissior.'s Public Oo:ume.:-
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Room at(1717 HIStreet N.V.,--Washington, D.C. 2C555 anc'in :ne. local publi:
document. room-at Brooks. Memorial Library, 22' Main Stree,' Erattlebore, Verment,
- nema, uwels.
Acditionally, a copy cf this decision 211' :e filed with tne Secre a y c'
- ns Ccamission for review by the Commissio? ' -a:: rdance with 10 CFR Section 2.205(c) of the Commission's regula-i r.s.
As cr: viced in-10 C:R 2.2C5(c), tnis cecision will :enstitute fira~ a:-icn of.he "cmmission-:wenty-f'vs-(25) cays af.s-ne cate of issuance, unies:
.s
- mmission 0. its own
^
- i:r insthe es tr.e. review cf :nis decisi:r,'- 'n tna- -ime.
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Da e: a: Estnesca, Marylanc tris ::
d ay f,.. --
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, 1950
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