ML070670425

Confirmatory Action Letter Alloy 82/182 Pressurizer Butt Welds

ML070670425
Person / Time
Site:	Diablo Canyon
Issue date:	03/15/2007
From:	Dyer J Office of Nuclear Reactor Regulation
To:	Keenan J Pacific Gas & Electric Co
Wang, A B, NRR/DORL/LPLIV, 415-1445
References
TAC MD4150, NRR-07-003
Download: ML070670425 (5)

Text

M arch 15 , 20 07 CA L N o. N RR-07-0 03 M r. Jo hn S. Ke ena n Se ni or V ic e P resi den t an d C hi ef Nuc le ar Off ic e Pa ci f ic Gas and E le ctri c C ompa ny Di abl o C any on Po w er P la nt P.O. B ox 77 000 0, M ai l Co de B3 2 Sa n F ranc is co, CA 94 177-000 1 S U B JE C T:

C ON F IR M A TOR Y A C TION L E TTE R , D IA B L O C A N Y ON P OW E R P L A N T, UN IT NO. 2 (TAC NO. M D4 150)De ar M r. K een an: Thi s l e tt e r co n fir ms c o mmi tme n ts b y P a ci fic Ga s & E l e ct ri c C o mp a n y (P G&E) i n r e gar d t o Al lo y 82/182 bu tt w el ds in the pre ssu riz er a t D ia bl o C any on Po w er P la nt (D CP P), Un it No. 2.T h e di s c o ve r y, in O c t o b e r 20 0 6 , of f iv e ci r c u m f e r e n t ia l i n d ic a t io n s in t h r e e di s s im il a r m e t a l (D M)w e l d s o n t h e p re ss u ri z e r a t th e W o l f C re e k Ge n e ra ti n g S ta ti o n (W o l f C re e k) r a i se d s a fety con cern s b ase d o n th e s iz e a nd lo cati on of the in di cati ons. A t W ol f C reek, thre e i ndi cati ons w ere in the pre ssu riz er s urge n oz z le-to-sa f e e nd w el d, a nd tw o s epa rate in di cati ons w ere in the safety an d re li ef noz z le-to-sa f e e nd w el ds. Thes e fin di ngs al so in di cate d th at s igni f ic ant conce rns mig ht exist w ith the inspec tion sched ules f or addr essing the pres sur iz er w eld co n ce rn s i ss u e d b y t h e i n d u st ry-s p o n so re d M a te ri a l s R e l i a b i l i ty P ro gra m (M R P), i n "P ri ma ry S y st e m P i p i n g B u tt W e l d I n sp e ct i o n a n d E v a l u a ti o n Gu i d e l i n e (M R P-1 3 9)."The N ucl ear Re gula tory C ommis si on (NR C) is co nce rned ab out the pres suri z er s urge n o z z l e-t o-s a fe e n d w e l d i n d i ca ti o n s, a s th i s i s th e fi rs t ti me t h a t mu l ti p l e c i rc u mfer e n ti a l p ri ma ry w ater str ess-cor ros ion crack ing (PW SCC) indications have been identif ied in a w eld. Th is co n d i ti o n c a l l s i n to qu e st i o n t h e d e gre e o f sa fety ma rgi n p re se n t i n p a st s tr u ct u ra l i n te gri ty ev al uati ons for f la w ed DM w el ds sus cep tib le to PW SC C, si nce mul tip le stre ss-co rrosi on crac king flaw s may grow i nde pen den tly an d u lti matel y grow togethe r, si gnifica ntl y red uci ng the tim e f rom f law ini tiat ion to leak ag e or rupt ure. T he siz e of the relief noz zl e-t o-s af e end f law is al so of conc ern, as thi s flaw ha s a much l arger a spe ct ra tio tha n th ose as sumed i n th e esti mates use d to es tabl is h th e b asi s for co mpl eti ng the ba sel in e i nsp ecti ons requi red by the in dus try-spo nso red M RP. L arger a spe ct ra tio s c oul d re sul t i n a chi ev in g a c riti cal flaw si z e a nd ru p tu re b e fore t h e o n se t o f de te ct a b l e l e a kage. The l ong-term re sol uti on of thi s i ssu e i s e x pec ted to i nv ol v e c han ges to the Ameri can S oci ety of Mech an ic al E ng ine er s Bo ile r and Pr es su r e Ve ss el Co de (A SME Co de), and w ill in volve cha nges to the N RC regul ati ons i n Ti tle 10 of the Co de of F ede ral R egu la tio ns (1 0 C F R), Pa rt 50 , S ecti on 50.5 5a, "Co des an d s tand ards." The de v el opme nt o f the N RC regul ati ons ,

J. S. K een an w heth er th e rule adopts the ASM E Code standar ds or def ines separ ate r eq uirem ents , w ill li k ely ben efit from add iti ona l ope rati ng ex peri enc e, c onti nui ng ass ess ments, and an al y si s b ei ng co n d u ct e d b y t h e N R C a n d t h e M R P. Un til N RC regul ati ons are rev is ed, it is ne ces sary to esta bl is h a mi ni mum se t of en han ced reac tor c ool ant sy stem (R CS) D M bu tt w el d i nsp ecti on ex pec tati ons for ni ckel-b ase d Al lo y 82/182 pre ssu riz er s urge, sp ray , sa f ety , an d re li ef noz z le bu tt w el ds, in cl udi ng safe e nd w elds, t o supplem ent existing inspection and oth er re q uirem ents of the ASM E Code and NRC r e g u l a t i o n s. I n a d d i t i o n , e n h a n c e d m o n i t o r i n g o f R C S l e a ka g e i s n e e d e d t o p r o m p t l y i d e n t i fy any thro ugh-w al l f la w s i n th e p ress uri z er s urge, sp ray , sa f ety , or rel ie f no z z le D M bu tt w el ds or safe en d D M bu tt w el ds to p rev ent add iti ona l degrad ati on f rom o ccu rrin g. The a bov e a cti ons provide reasona ble assura nce tha t the re is no undue risk to the health and saf ety of the public w h i l e t h e N R C r e gul a ti o n s a re r e v i se d. T he NRC comm unicat ed the need f or near-t erm enhancem ents to the indust ry throug h public meeti ngs he ld on N ov embe r 30 , 20 06, De cembe r 20 , 20 06, and F ebru ary 2, 200 7. Li cen see s sub mitted l etters v ol unta ril y co mmitti ng to the enh anc ed in spe cti on and l eakage mon ito rin g r e qu i r e me n t s. A ft e r t e l e c o n fe r e n c e s w i t h s p e c i fi c l i c e n s e e s h e l d b e t w e e n F e b r u a r y 1 2 t h r o u gh Feb ruary 23 , 20 07, the li cen see s s ubmi tted sup pl emen tal co mmitment le tters add ress in g the N R C s t a ff's c o n c e r n s r e ga r d i n g i n s p e c t i o n , c o mp e n s a t o r y a c t i o n s , a n d r e p o r t i n g.In y our le tter d ated F ebru ary 20 , 20 07 (Agenc y w id e D ocu ments Acc ess an d M ana gement System (ADAM S) Acces sion No. M L070580 128), you described act ions y ou w ill tak e at DCPP, U n i t N o. 2 for t h e p re ss u ri z e r d i ss i mi l a r me ta l b u tt w e l d s co n ta i n i n g A l l o y 8 2/1 8 2 ma te ri a l. These commi tments add ress: 1) co mpl eti on sch edu le s for i nsp ecti on/mi tigati on of the w el ds;2) R CS l eak mon ito rin g f requen cy , ac tio n l ev el s, a nd acti ons; 3) repo rtin g require ments, and 4) re i n sp e ct i o n fre que n ci e s. The N RC sta f f ha s re v ie w ed thes e a cti ons an d c ommitmen ts a nd agrees the acti ons an d commi tments are app ropri ate to a ddre ss the pote nti al of PW SC C of the app li cab le pre ssu riz er di ssi mil ar me tal bu tt w el ds con tai ni ng Al lo y 82/182 mate ria l w ith cl ari f ic ati ons on tw o o f the commi tments as in di cate d i n b ol d b el ow regard in g RC S le ak moni tori ng acti on le v el s a nd n o ti fic a ti o n o f ch a n ges t o c o mmi tme n ts.

• If a qu a n ti ty o f l e a kage c a n b e a ss i gne d t o a s o u rc e o th e r th a n t h e p re ss u ri z e r, a n d t h a t q u a n t it y d e c r e a s e s t h e un id e n t if ie d le a k a g e be lo w b o th thre sho ld s (0.1 gp m [g allon per minut e] st ep increas e or 0.25 gpm above baseline), this w ill n e gat e t h e r e qui re me n t for sh u td o w n a n d/o r p re ss u ri z e r A l l o y 6 0 0/8 2/1 8 2 b u tt w el d b are metal ex ami nati on.*

PG&E wi ll inf orm the NRC in w riting p ri o r to a n y r e v i si o n o f th e p re ss u ri z e r b u tt w e l d i n sp e ct i o n s ch e d u l e s o r co mmi tme n ts d e sc ri b e d i n t h i s l e tt e r.These cl ari f ic ati ons w ere di scu sse d w ith an d a greed upo n b y y our staff du rin g a te le pho ne di scu ssi on on M arch 8, 200 7, b etw een D onn a J aco bs, Vi ce Pre si den t - N ucl ear Se rv ic es and Mich ele Evan s, Dir ec t or - Divis ion of Com po ne nt In t eg r it y.

J. S. K een an Pu rsua nt to S ecti on 182 of the A tomi c E nergy A ct, 4 2 U.S.C. 22 32, y ou are requi red to:1)

No tify me immed ia tel y i f y our und ersta ndi ng di f f ers f rom tha t se t forth ab ov e;2)

N o ti fy me i f for a n y r e a so n y o u c a n n o t co mp l e te t h e a ct i o n s a n d c o mmi tme n ts w ithin the spec if ied schedule and advi se me in w riting of y our m odif ied schedule in ad v anc e o f the ch ange; and3)

N o ti fy me i n w ri ti n g w h e n y o u h a v e c o mp l e te d t h e a ct i o n s a n d c o mmi tme n ts a d d re ss e d i n t h i s C o n fir ma to ry A ct i o n L e tt e r.Issua nce of thi s C onfirmato ry A cti on Lette r do es not prec lu de is sua nce of an ord er formal iz in g the above com mit me nts or req uiring other actions on the part of the licensee; nor does it prec lu de the NR C f rom taki ng en f orce ment acti on f or v io la tio ns of NR C requi rements tha t may have promp ted t he issuance of this letter. In addition, f ailure to tak e the act ions addres sed in thi s C onfirmato ry A cti on Lette r may res ul t i n e nforcement acti on.In a cco rdan ce w ith 10 C FR 2.3 90 of the NR C's "Ru le s o f P racti ce," a c opy of thi s l etter and your respon se w ill be made avail able electr onically f or public inspect ion in the NRC Public Do cumen t R oom or from the N RC's A DA M S, acc ess ib le from the NR C W eb si te a t http://w w w.nrc.gov/read in g-rm/ada ms.html. To th e e x tent pos si bl e, y our resp ons e s hou ld no t in cl ude an y pe rson al pri v acy , pro pri etary , or safeguards in f ormati on so that it can be mad e avail able to the Public w ithout redact ion. If person al priv acy or propr ietar y inf orm ation is nec ess ary to prov id e a n a cce ptab le res pon se, then pl eas e p rov id e a bra cketed cop y of y our resp ons e th at i den tifie s th e i nformatio n th at s hou ld be pro tecte d a nd a re dac ted cop y of y our resp ons e th at d el etes su ch in f ormati on. If y ou request w ith hol di ng of such mate ria l, y ou must specif ically identif y the por tions of y our r espons e that y ou seek to have w ithheld and provide i n deta il the bas es f or your claim of w ithholding (e.g., ex plain w hy the disclosu re of inf orm ation w ill crea te a n u nw arran ted in v asi on of perso nal pri v acy or prov id e th e i nformatio n re quire d b y 10 CF R 2.39 0(b) to s upp ort a reque st for w ith hol di ng con f id enti al co mmerci al or f in anc ia l in f ormati on). If safeg uard s i nformatio n i s n ece ssa ry to prov id e a n a cce ptab le res pon se, pl eas e prov id e th e l ev el of pro tecti on des cri bed i n 1 0 C FR 73.21.

Sin ce r ely,/R A/

J. E. D y e r, D i re ct o r Of f ic e o f N ucl ear Re acto r R egul ati on Do cket No. 50-323Li cen se No. D PR-82 c c: S e e n e x t p a ge J. S. K een an Pu rsua nt to S ecti on 182 of the A tomi c E nergy A ct, 4 2 U.S.C. 22 32, y ou are requi red to:1)

No tify me immed ia tel y i f y our und ersta ndi ng di f f ers f rom tha t se t forth ab ov e;2)

N o ti fy me i f for a n y r e a so n y o u c a n n o t co mp l e te t h e a ct i o n s a n d c o mmi tme n ts w ithin the spec if ied schedule and advi se me in w riting of y our m odif ied schedule in ad v anc e o f the ch ange; and3)

N o ti fy me i n w ri ti n g w h e n y o u h a v e c o mp l e te d t h e a ct i o n s a n d c o mmi tme n ts a d d re ss e d i n t h i s C o n fir ma to ry A ct i o n L e tt e r.Issua nce of thi s C onfirmato ry A cti on Lette r do es not prec lu de is sua nce of an ord er formal iz in g the above com mit me nts or req uiring other actions on the part of the licensee; nor does it prec lu de the NR C f rom taki ng en f orce ment acti on f or v io la tio ns of NR C requi rements tha t may have promp ted t he issuance of this letter. In addition, f ailure to tak e the act ions addres sed in thi s C onfirmato ry A cti on Lette r may res ul t i n e nforcement acti on.In a cco rdan ce w ith 10 C FR 2.3 90 of the NR C's "Ru le s o f P racti ce," a c opy of thi s l etter and your respon se w ill be made avail able electr onically f or public inspect ion in the NRC Public Do cumen t R oom or from the N RC's A DA M S, acc ess ib le from the NR C W eb si te a t http://w w w.nrc.gov/read in g-rm/ada ms.html. To th e e x tent pos si bl e, y our resp ons e s hou ld no t in cl ude an y pe rson al pri v acy , pro pri etary , or safeguards in f ormati on so that it can be mad e avail able to the Public w ithout redact ion. If person al priv acy or propr ietar y inf orm ation is nec ess ary to prov id e a n a cce ptab le res pon se, then pl eas e p rov id e a bra cketed cop y of y our resp ons e th at i den tifie s th e i nformatio n th at s hou ld be pro tecte d a nd a re dac ted cop y of y our resp ons e th at d el etes su ch in f ormati on. If y ou request w ith hol di ng of such mate ria l, y ou must specif ically identif y the por tions of y our r espons e that y ou seek to have w ithheld and provide i n deta il the bas es f or your claim of w ithholding (e.g., ex plain w hy the disclosu re of inf orm ation w ill crea te a n u nw arran ted in v asi on of perso nal pri v acy or prov id e th e i nformatio n re quire d b y 10 CF R 2.39 0(b) to s upp ort a reque st for w ith hol di ng con f id enti al co mmerci al or f in anc ia l in f ormati on). If safeg uard s i nformatio n i s n ece ssa ry to prov id e a n a cce ptab le res pon se, pl eas e prov id e th e l ev el of pro tecti on des cri bed i n 1 0 C FR 73.21.

Sin ce r ely,/RA/

J. E. D y e r, D i re ct o r Of f ic e o f N ucl ear Re acto r R egul ati on Do cket No. 50-323 Li cen se No. D PR-82 c c: S e e n e x t p a ge Dist ribu tion: PU BLI C LPL IV R/F Rid sNr rP M AW ang Rid sNr rLA LFei z ollah i Rid sNr rD orlL pl4 Rid sO gcR p Rid sAcr sAcnw M ailC ente r Rid sRg n4M ailC ente r Rids NrrOd Rid sNr rD orl Rid sNr rD ci Rid sO EM ailC ente r Rid sEdo M ailC ente r DC ulliso n, ED O R IV VD ricks, O PA , R IVW M aler , S tat e Li aison O ffi cer, R IV Rid sNr rD irs TLupold , NRR ESull ivan, NRR RPasc arel li, NRR Rid sNr rD ciCp nb Rid sNr rA des A DA MS A ccess ion N o. ML070670425 OFFIC E CPN B DC I LPL4/PM LPL4/LA LPL4/BC TECH ED DIR S/TA NAM E TLu po ld ESulli va n AW an g LFe iz oll ah i DTe ra o HC ha ng RPa scare lli DATE 3/1 3/0 7 3/1 3/0 7 3/1 2/0 7 3/9/07 3/1 2/0 7 2/2 8/0 7 3/1 2/0 7 OF FI C E C PN B/BC D R P/D R GN 4 D OR L/D D C I/D AD ES/AD N R R/D NAM E TCh an AHo w ell , III CH an ey M Eva ns JGro be JDy er DATE 3/1 4/0 7 3/1 4/0 7 3/1 9/0 7 3/1 4/0 7 3/1 4/0 7 3/1 5/0 7OFFICIAL RECORD CO PY Jan uary 20 07 Di abl o C any on Po w er P la nt, U ni ts 1 an d 2 cc: NR C Re si den t Ins pec tor Di abl o C any on Po w er P la nt c/o U.S. N ucl ear Re gula tory C ommis si on P.O. B ox 36 9 Av il a B eac h, C A 93 424 Si erra Cl ub Sa n L uci a C hap ter ATTN: An drew C hri sti e P.O. B ox 15 755 Sa n L ui s Obi spo , C A 93 406 M s. N anc y C ul v er Sa n L ui s Obi spo M othe rs for P eac e P.O. B ox 16 4 Pi smo B eac h, C A 93 448 Ch ai rman S a n L u i s Ob i sp o C o u n ty B o a rd o f S u p e rv i so rs 105 5 M onte rey S treet, Su ite D 430 Sa n L ui s Obi spo , C A 93 408 M r. Truman Bu rns M r. R obe rt K in osi an Ca li f orni a P ubl ic U til iti es Co mmissi on 505 V an Ne ss, Ro om 4 102 Sa n F ranc is co, CA 941 02 D i a b l o C a n y o n I n d e p e n d e n t S a fety C ommitte e A TTN: R o b e r t R. W e l l i n gt o n , E s q. Le gal Co uns el 857 C ass S treet, Su ite D M onte rey , C A 93 940 R e gi o n a l A d mi n i st ra to r, R e gi o n I V U.S. N ucl ear Re gula tory C ommis si on Ha rris Tow er & P av il li on 611 R y an Pl az a D riv e, S ui te 4 00 Arl in gton, TX 76 011-806 4 A n t o n i o F e r nán d e z , E s q.Pa ci f ic Gas & El ectri c C ompa ny P.O. B ox 74 42 Sa n F ranc is co, CA 941 20 Ci ty E di tor The Trib une 382 5 S outh H igue ra S treet P.O. B ox 11 2 Sa n L ui s Obi spo , C A 93 406-011 2 Di recto r, R adi ol ogic He al th B ranc h Sta te D epa rtment o f H eal th S erv ic es P.O. B ox 99 741 4, M S 761 0 Sa cramen to, C A 95 899-741 4 M r. Ja mes D. B oy d, C ommis si one r Ca li f orni a E nergy C ommis si on 151 6 N in th S treet (M S 31)Sa cramen to, C A 95 814 M r. Ja mes R. B ecker, V ic e P resi den t Di abl o C any on Operati ons an d S tati on Di recto r Di abl o C any on Po w er P la nt P.O. B ox 56 Av il a B eac h, C A 93 424 Jen ni f er Tan g Fie ld Re pr es en t at ive Un ite d S tates S ena tor B arba ra B ox er 170 0 M ontgomery S treet, Su ite 24 0 Sa n F ranc is co, CA 941 11