ML20069B478

Examination of Failed Studs from No. 2 Steam Generator at the Maine Yankee Nuclear Power Station

ML20069B478
Person / Time
Site:	Maine Yankee
Issue date:	02/28/1983
From:	Czajkowski C BROOKHAVEN NATIONAL LABORATORY
To:	Office of Nuclear Reactor Regulation
References
CON-FIN-A-3400 BNL-NUREG-51594, NUREG-CR-2993, NUDOCS 8303160620
Download: ML20069B478 (32)

Text

{{#Wiki_filter:- NUREG/CR-2993 BN L-NUREG-51594 Examination of Failed Studs From No. 2 Steam Generator at the Maine Yankee Nuclear Power Station i Prepared by C. Czajkowski Brookhaven National Laboratory h$b ' ion !!A 188 8 e 88888, P PDR

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NUREG/CR-2993 ,,8NL-NUREG-51594 Examination of Failed Studs From No. 2 Steam Generator at the Maine Yankee Nuclear Power Station Manuscript Completed: July 1982 D ts Published: February 1983 Prtpared by '/ 7' C. Czajkowski Brookhaven National Laboratory Upton, NY 11973 l Prcpared for -) Division of Engineering Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Wcshington, D.C. 20656 NRC FIN A3400 s wu-k 2 ) /

TABLE OF CONTENTS Page List of Figures 11 List of Tables 111 Abstract v

1.0 INTRODUCTION

1 2.0 VISUAL INSPECTION / DYE PENETRANT 1 3.0 6PTICAL METALLOGRAPilY 2 4.0 SEM/EDS 3 5.0 DISCUSSION 4

6.0 CONCLUSION

5 7.0 ACKNOWLEDGEMENT 6

8.0 REFERENCES

7 o L s ?W 9 f a i e

l I u l LIST OF FIGURES 4 Finure Pane J 1. Photograph of first "as received" stud 13 2. Photograph of second stud 14 l 3. Photograph of " cracked" stud 15 ) 4. Photograph of fracture faces of " cracked" stud 16 i 5. Optical photomicrograph of cracked stud's cross 17 I section i 4 6. Optical photomicrograph of a secondary crack 18 7. Optical photomicrograph of stud's microstructure 18 8. Low magnification SEM photo of the cracked stud's 19 fracture face i 9. SEM photo of nodular oxide 20 10. SEM photo of acicular oxide 20 11. SEM photo of fracture face prior to deoxidation 20 t 12. SEM photo of fracture face and secondary cracking 20 13. SEM photo of second area depicting secondary cracks 21 i 14. SEM photo of base material 21 15. EDS scan of base material for constituents 21 16. SEM photo of fibrous particulate 22 i 17. EDS scan of fibrous particulate 22 18. SEM photo of second fibrous particle 22 19. EDS scan of fibrous particle 22 a 20. SEM photo of apparent pit 23 21. EDS scan of apparent pit 23 22. SEM photo of smeared material 23 23. EDS scan of smeared material 23 l 24. SEM photo of second smeared area 24 25. EDS scan of second smeared area 24. 26. WDS scan of second smeared area for Mo 24 27. WDS scan of second smeared area for S 24 11

l l i LIST OF TABLES Table g 1 Typical Chemical and Mechanical Properties of ASTM 8 l A540-B24 Steel 2 Typical Certification for Sealant Used (Lot 505) 9 3 Typical Certification for Sealant Used (Lot 701) 10 4 Typical Certification for Sealant Used (Lot 702) 11 5 Typical Certification for Lubricant Used (Batch 55) 12 l l l iii

ABSTRACT l I Three studs removed from service on the primary manway cover from steam generator #2 of the Maine Yankee station were sent to Brookhaven National Laboratory (BNL) for examination. The examination consisted of visual / dye penetrant examination, optical metallography and Scanning Electron Microscopy / i Energy.Dispersive Spectroscopy (SEM/EDS) evaluation. One bolt was "through cracked" and its fracture face was generally transgranular in nature with numerous secondary intergranular cracks. The report concludes that the l environmentally assisted cracking of the stud was due to the interaction of l the various lubricants used with steam leaks associated with' this manway 1 Cover. i i l l I i l l V

1.0 INTRODUCTION

During March 1982, at a maintenance outage of the Maine Yankee Power ] Plant, 5 of 20 primary manway studs failed during removal of the (cold leg) primary manway cover from steam generator #2. Prior to this outage, the manway cover had been leaking, with retorquing of the studs and injection of sealant into the stud used by the utility as methods of controlling the leakage. Since failure of this cover would result in a breach of the primary pressure boundary, the Materials Engineering Branch of the United States Nuclear Regulatory Ccmmission (U.S.N.R.C.) requested that BNL perform an independent failure analysis on three of the bolts from the #2 steam generator manway cover. 7 The examination for this analysis included:

1) Visual inspection / photography / dye penetrant

2) Optical metallography

3) SEM/EDS analpis 2.0 VISUAL INSPECTION / PHOTOGRAPHY / DYE PENETRANT The three studs received at BNL were approximately 10 1/2" long, and 1 1/2" in diameter and were surveyed by BNL Health Physics personnel as having a dose rate reading of approximately 2 mR/hr at contact.

The first stud examined (Figure 1) had apparent disruption to the thread area which had the appearance of damage caused by the use of a vise grip-type tool. There was also a white fibrous type coating on the opposing thread area of the stud (discussed in the SEM section). 1

The second stud examined (Figure 2) appeared to have residue from prior dye penetrant examinations and had a nut threaded on to one end of the stud. This nut was removed prior to dye penetrant examination by cutting (due to the extremely tight fit to the stud). Figure 3 is a photograph of a "through cracked" stud. The crack is approximately 2 1/2" into the thread area " inserted end" of the stud. The fracture face of the stud (Figure 4) was relatively flat and had a black oxide appearance. Dye penetrant examination was performed on the first two studs (Figures 1 and 2) using Spotcheck Brand (all Formula B) penetrant type SKL-HF/SKL-S developer type SKD-NF and cleaner / remover type SKC-NF. There were no relevant indications seen on the two studs. It should be noted that there was a tight black adherent film on the thread area of all studs examined, possibly from prior lubricant application (see SEM section). No attempt was made to dye penetrant examine the cracked stud in order to keep exterior contamination to a minimum prior to SEM/EDS evaluation. 3.0 OPTICAL METALLOGRAPHY A longitudinal section was made of the small end of the cracked stud, perpendicular to the main fracture face. It was then mounted, etched and polished (Figure 5). It can be clearly seen in the photomicrograph that numerous secondary cracks are present, initiating at the main fracture (areas A-F). These cracks had some fern-like branching associated with them which is normally indicative of environmentally assisted cracking. The major secondary cracks appeared to be genera'lly transgranular in nature. The / microstructure of the stud material (Figure 6 & 7) was that of a quenched and f tempered martensite with a fine grained microstructural appearance. This microstructure is typical of an ASTM A540-B24 steel (Table 1). 2

l 4.0 SEM/EDS The fracture face and a limited amount of thread area of the "through p l cracked" bolt was examined by SEM/EDS examination prior to any deoxidizing ( treatments in hopes of determining if any corrodent species were present.- l l l The "as received" surface of the fracture face had a very flat and heavily oxidized surface (Figure 8) with the oxide varying from a nodular type (Figure 9) to an acicular shape (Figure 10). Initial SEM observations were that the fracture face was predominantly transgranular with no evidence of any ductile tearing. Af ter some sections were deoxidized by an Endox 215

solution, however, various areas of apparently intergranular secondary cracking were revealed (Figures 11-13). This type of secondary cracking would be a definite indication of an environmentally assisted corrosion phenomenon.

An EDS scan of the base metal was performed (Figures 14 and 15) and showed characteristic peaks of Fe, Cr, Mn and Ni. .These peaks would be typical for this alloy. Various particles and areas of apparent material smearing were scanned for constituents using EDS. The first particle scanned from stud No. 2C6 was fibrous in appearance (Figures 16 & 17) and had quite high peaks of silicon and nickel in relation to the Fe alloy background. The scan also showed trace amounts of S, Ca and Cr. The high silicon content is probably related to the j use of the silicon base Furmanite sealer used by the utility to seal the l leaking stud holes. The high nickel content is attributed to the utility's use of Fel-Pro-5000, a nickel-base lubricant. (For typical certifications of materials used at Maine Yankee (see Tables 2-5.)) A second fibrous particle ( scanned (Figures 18 & 19), however, showed only peaks of Fe, Cr and Ni. Another area scanned (Figures 20 & 21) appeared to be a pit and had a l lead (Pb) peak in addition to Si, Cr, Fe and Ni. The appearance of lead may t j be attributed to the Fel-Pro which allows up to 25 ppm total lead in its specification. 3 t,.- -.

) EDS analysis of a smeared area (Figures 22 & 23) showed peaks of Si, S, Ca and Fe only. A second smeared area (Figure 24) had such a high peak in sulfur _(Fig-I ure 26) that a wavelength dispersive spectrographic scan was accomplished to determine if molybdenum was present with the sulfur. It can be clearly seen (Figures 27 & 28) that this particular area is quite concentrated in Mo which is indicative that a molybdenum disulfide type lubricant may have been used sometime in the service history of the stud. 5.0 DISCUSSION Since the cracking of the steam generator manway studs was associatd with leaking gaskets, it is worthwhile to examine the observed effects of pressurized water reactor (PWR) primary coolant on high strength low alloy bolting materials. A review [1] was performed by BNL on incidents of boric acid wastage corrosion at seven nuclear units. All incidents involved a primary coolant leaking mechanism and in po instance was cracking observed. All degradation occurred by a general wastage / corrosion mechanism. This being the case; it is therefore logical to assume that the addition of other environmental variables must be made in order to crack these materials in either a transgranular or intergranular manner. The most obvious source of these contaminants is the lubricanL. rpplied to these materials in service. Work done at BNL [2,3] on turbine disc steels has shown that molybdenum disulfide lubricants can have a marked effect on lowering the ultimate tensile strength of high strength low alloy steels when exposed to a steam environment on notched tensile specimens. 4

A metallurgical failure analysis [4] performed on steam generator manway studs at the Oconee Unit 3 power station ascribed the intergranular attack on the bolts to the use of molybdenum disulfide lubricants. Kay [5] has cited that MoS2 can oxidize in the presence of air and moisture to produce molybdenum dioxide and sulfuric acid which would be quite detrimental to a martensitic steel. Finally, a report issued by the Swansea Tribology Centre [6] on molybdenum disulfide lubrication has listed these precautions on the use of the lubricant: l (quoted in part) l l "l) Always remember that where conditions exist which will tend to cause l corrosion, the presence of molybdenum disulphide may increase the extent of the corrosion.

2) Wherever possible eliminate the presence of corrosive materials such as acids, brines, or water and use corrosion - resistant substrates."

It is, therefore, logical to assume that some interaction between the leaking steam and the sulfur containing lubricants on the bolts may have led to the premature failure of the bolt by a stress corrosion crack mechanism.

6.0 CONCLUSION

1) The cracked bolt failed in a generally transgranular mode with-numerous secondary intergranular cracks.

2) This cracking is considered environmentally assisted in nature and was r

typical of a stress corrosion cracking phenomenon. l l l l 5

3) Since prior investigations have shown that high strength low alloy steels in primary coolant will have a wastage-type corrosion only, this cracking is considered to be the result of the interaction of primary water / steam with the use of sulfur containing lubricants.

7.0 ACKNOWLEDGEMENT The author wishes to thank R. Sabatini for the SEM/EDS work; L. Gerlach and D. Becker for the metallography; .0. Betancourt for her typing and Dr. J. R. Weeks for his continuing support. i 6 1

8.0 REFERENCES

1. Czajkowski, C., BNL-NUREG-31098, March,1982. 2. Czajkowski, C., BNL-NUREG-28724, October, 1980. 3. Czaj kowski, C., BNL-NUREG-29964, March,1981. 4. Burck, L. H., Foley, W. J., Report No. IE-123, April, 1981. 5. Kay, E., Wear, 12 (1968), 165-171. 6. Lansdown, A. R., Report No. 79/419 ESA (ESTEC) Contract No. 2261/74. l t I l t 7

_. -. -. _ ~. 4 TABLE 1 4 i TYPICAL CHEMICAL AND MECHANICAL PROPERTIES OF i ASTM A540-B24 STEEL i Product. Variations %, Chemical Requirements over or under i r J Carbon 0.37-0.44 0.02 Manganese 0.70-0.90 0.04 t Phosphorous, max. 0.025 0.005 Sulfur, max. 0.025 0.005 Silicon 0.15-0.35 0.02 I Chromium 0.70-0.95 0.05 Nickel 1.65-2.00 0.05 Molybdenum 0.30-0.40 0.02 Vanadium t Mechanical Requirements l Grade Class Diameter B24 3 to 3, incl. i % Red. of Surface Hard-l Tensile Strength Yield Strength Elongation

Area, ness, Brinell min.

0.2 offset, min. % in 2 in. min. min. max. a 145 ksi 130 ksi 12 40 293 363 L 8

EL:URMANiT.EE L,._._.._,. m su;CAPORAT(o $29 VIKING drive

• VIRGINtA BEACH.vsAGINIA 23452. PHONE 8804148C4182 - TELE.x 223475 TABLE 2 TYPICAL CERTIFICATION FOR SEALANT USED (LOT 505)

MATERIAL CERTIFICATION REVISION 1 August 14, 1981 Material: rJu?fte-uticar Criac.- Co= pound ;Fa500i."I.ot"Sof 505 ~~ Expiration date for Compound: July 31, 1982 This is to certify that the analysis'results of a typical sample of the above compound, analyzed by an independent test laboratory, is as follows: l l TOTAL LEACHABLE Chlorine 38 26 Flourine __ _11 <.1 l Sulfur (As 57. cm.v.3-e wrc = -- < _14 a.; wm,,;g;;.yg (-? " f_"2 Anti =ony 5.0.03 Arsenic f.O.03 Cadmium $_.0.03 Lead s.0.3 Tin 13 Zinc 4 0.05 Mercury 0.002 Note: Results in microgram / gram

• Not Measured A

D. F. Ln foth Engineering Manager Ref: CT&E - 8/6/81 4 DFL/ tim MAltiE YAflKE E ATOMIC PO*/.'ER CO. QUALITY COff1ROL lt4SPECTED SAT. W UNSAT. DATE /.9/M.*.f[k INSPECTOR I; 9 SPE Ciats51S 04tWE LE as $( AtWG AND OM SAT ( MACMWWG $(R ($ n

. [$URM ANITEi. k i ] INCo4PORATED $29 VIKING ORivE

• VlAGINIA BE ACH.VIRGINI A 234$2 PHONE (E* 4) 4864187. TELEX 873475 I

TABLE 3 TYPICAL CERTIFICATION FOR SEALANT USED (LOT 701) ( MATERIAL CERTIFICATION October 19, 1981 Material: 75E:EiEife9@c1Tr.*cFiWW:2pWunEndtr,-'17o7E7o1C Expiration date for compound: October 16, 1982 This is to certify that the analysis results of a typical sample of the above test laboratot/, is as follows: compound, analyzed by an independent TOTAL LEACHABLE Chlorine 179.5 32.7

19. O _..

_._____0g6., .FluoLjte __,__ =___.., i M== ^1B::: {SG1Eurq ;_.=;...;1-;- ~~.su 0.11 Anticony < 0.02 Arsenic 4.0.005 Cadmiu:n 4 0.05 Lead 4 0.002 Mercury 4 0.03 Tin 4 0.05 [ Zinc Note: Results in microgram / gram

• Not Measured I

re l D. F. L croth i f Engineering Manager ) Ref: Jennings Laboratories Inc. DFL/tfm l l MAINE YA;;KEE ATOMIC POWER CO. l QUAllTY CO?: TROL INSPECTED SAT..... V oATE L9/.E.1f.1.!... utesAT m27gbyy}gQ 10 ..,cws s o u~r sta= scatw awo ossne u4cmui o sza.trs m.

FLJAMANiTiE m*b pOmattD 5;s wealNO Daivt. vanGiNia BE ACM vsRGtNsA 234$7. PHONE 1804 486 s122. TELEX E2uts TABLE 4 TYPICAL CERTIFICATION FOR SEALANT USED (LOT 702) MATERIAL CERTIFICATION December 4, 1981 Materia 1: Dits_;23uciWa6F5706ET51ok'MDhAf Expiration date for compound: December 4, 1982 This is to certify that the analysis results of a typical sample of the above comoound, analyzed by an independent test laboratory is as follows: Total I,cachable chlorine 246.2 2 S. 6 Fluorine 7.4,_0__ .65_., gggs?,'s f 2- -C.l wh-_=.. ._~ L--ms w r=n=r-===:-=azim T =F ' Antimony 0.18 Arsenic 40.02 Cadmium <0.005 Lead 40.05 Mercury <,0.002 Tir: <0.05 Zinc (0.05 Note: Results in microgram /aram Not Measured ( b M D. F. Limroth .___ Engineering Manager REF: Jennings Laboratories, Inc. 12/04/81 \\^TY DFL/tfm M* 0 " un/ unSAT. ,gg tusrccion sT 11 s acia usts o %.%: tras se at =c aso e~ site .e-. mc stav.cis

..m 3,-> t.t g ell!' ; ..C.. -"h1P' !5, <y TABLE 5 ta <$a-% TYPICAL CERTIFICATION FOR LUBRICANT USED (BATCH 55) ( tt 1 (w,.., J *- L g --t,v; u. rT W 2s->.M: .J d FAO A-5::30 AA T:~2 KO. J

• A C EAR CAAr.

ANT 3Elit LUBUCAh? CATZ Of A?R. 4(10/E1 y'ag. ym,-. < 'f $'f, <+ w crk IrJCA*r or c:r*.PL:AN ? [t b.*$ It is hereby certitled that the above batch of Tel-Pro F-$000 sects the follovfog purity standardst m%.Q: fffQ KAX:xvM A.:Du-7?s~ P25U~.~5 AsLz rea v-so00 ~ $g g;,- SPECir1 CAT 1CW SMPLC 11 SAMP!2 92 SA.KPLE f3 N% % pt - fotd riectine 200 pp 25 p;m 24 wo 15 p;m Q Total Chlorine 30 ppm 420 ppe (40 ppm 420 p;m L>e,49 wgro. - -= e = =Ms.., -- -<25.w-3'2: Pr=- MM retal Lead 25~p;se 7.5 ppm 7.5 ppa a.a p,n '*I rot d tin 25 p;n 11.5 FPe sh h Total tine 25 psa G 4 PP' ~ ~ F.s M rotal Cadrfwe 2 p;n 0.8 ppe .{g' % q Total Aescury 2 pp:n 0.17 pre f- } % otal Cc;pe.r 50 ppa 2.6 VP' ~ ~~~ I iY WOTE: Crig!.nal test report on this hatch 27: 7 L-P90 ZhC;aRPCT.A:7.D f">h9 of N-5000 is ca flie at it;,-PRO 1450 N. nccoMICK BLVD. h,ffq 9') ZNCORPCRA ~rD._ Copies are avalla.ble Skokie, Ill. 60076 r$if upa:1 request. Test results are S'= e furthez shown on each can ?!11ed h}) from this batch of r.aterials. WI w $A-- C:!icer of Cxpany { Prod. Mct., Ch er=. Prod. ?!v. Title 535 R:2 D AND ZvCRM 10 Err 3RZ KZ TEZS TATra =.- 7.. Ik A d % :'.i t % E - f ~ Fot.rry Public .',/ S b "g % -+[g""g NE YANKEE ATOMIC POWER = w4u -- 3scu1=<,Ns,sc,,o CA7g Q*--[/.. UNsAT* INsFECTOR - .A,. e' g?e &N t. 1.:.g.n E'~'i?y..r:5.y?l2-n.W+N.5~kfIp.?L,5 :$:',.%':xpmWE5,U.2 2M. e ~ n., . = -. ~ s.- -n e.. J:5 -:,. t - t w-.L, : -=a 52 V:-J M"Y2 L* e - s: am-w o 1 -:-r e.e= --w -i : -P. 12

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y },.:d. / . g 3,7 - -'s. i ^ r.** I / l .g4 E. ' j' \\ / _.y. ~j ' 4 ; -s.,..,- w 3. t I i s, i ,~l , of - l ^ 100x 500x Figure 11. SEM photo of fracture face prior Figure 12. SEM photo of fracture face to deoxidation treatments. depicting intergranularity of ) secondary cracks.

I ~ ~ g, j 1-y .. )k -a 1 ~ } ~-) .c .~ ' ,3 .v ; y',, ', -Q - s ,c, ,m. ? ~ t' .. ' r -.- ~ \\, {. -..j g fjr .,--[: - y. .,- n m 7 n 6 t,: -.c . x, A.4 %

M, A -

su f( T .i.. s c. T" . n., m y s- .n g}.4.e VM /~ ' '.,,..,~ L,,', ...d. 3 _ .m h . Ca

• s 500x Figure 13. SEM photo of second area on the fracture face depicting y

secondary intergranular cracks. J mW g .n .. L.'.' ~ , ') 6 ,b. i'. h J- -. * '.gh. ',

• 5 5.**.7 [ _.

4,3 "". (, -'%'f' 9- .Q, f I c-. m +. S,. T'_ y Y 4A. .s,_., -.u .y* ,u n ,4* 9.f ? # * ' h-p_. ,-t[ i,. ' 5 $ ~ r f A.a -;Q2 &_3;,r..'E *_ ~ * . -r _.m.' ; s i~. '. '.y

+

'_s ,. f --t' ,;*.- 45 ~ z _f }.... f N m]!f it,f # T[ MC_'.'[8 - : ' pPh Mn ' i n .. F g k 6,., - *; - 1000x Figure 14. SEM photo of base material Figure 15. EDS scan of base material for area scanned. constituents.

..v c,,, lN>f(,! j.h A: IING 5 TART ' PHA11 ADD.020tEv.-~<M '00 EEs : l f ;,, /. / 'yI I l t g f i 1 8 7., 4 i - ' b -~ Fe 1 s.. l [ t]l 1 L yg

• Y 4.. J,e}

p i ZI Si

Ni

)N1 Q )' - - S Ca (r - w A ; :L i .10 2 2 e ' y 000' p::g5;; t 1gg g.p;gl 500x i l Figure 16. SEM photo of fibrous Figure 17. EDS scan of fibrous particle. [ particulate. U i i i n-- n x s % w w,.,;-- w p pw"w- ',i

• lY I

? ' 7 f.? l _ _~'p. ~ }[QG' c',$ 0 jq..

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• J.. 3 i

. wj - ['. d' p,

2. %... a f,.<l

f.g^jk

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o wr 1

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u w x -.a s. 500x Figure 18. SEM photo of second fibrous Figure 19. Constituents of second fibrous particle. particle scanned by EDS.

i I g,. ynn. thf$ ',M, '/e ~. '. .' ;'&s-r,,, i - .5.,,, f;f &,'i l ? f .,l3 ,) 3;

if { h.c-?* ]Fe* IW&Ch.4 k).W,;,-f $

g;g,[ ~, [.y, 3 _ ;-__; x.k i_,;; g."l'... Q 5%: k-:x:[ f. %...? q$ yl r. ' y ae. l < 5F M: t x; s . y. 3 _ +. Y " l..

s. }- -

- %...;...., $...s:. c,(?-:..'.. y W. _4 .A l i . A,_. m ,.y h,.. ~ <[ N! l '..'. *. s.I l f p 7r- +,y , g,.-

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e::

,t . % ~Q y* n. _ .s". m.- y e m...- I 1000x Figure 20. SEM photo of apparent pit on Figure 21. EDS scan of pit for chemical ) thread of the cracked stud. constituents. l r,> w I h . ~ ~, '.:*;,p'-f 4 d@ ;@ )af , A,i. !.4, ;, M.4,, g g, { y;%g.Q); a 3 M.Mi

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41. "

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f '..

• 500x Figure 22.

SEM photo of area of smeared Figure 23. EDS scan of smeared material material on thread area of area. the cracked bolt. - - ~

9, J.. o - : ~ .2, %p A ~ , + g... - /s..... ;;. . z,n. - ~,nf.c,. + x,-i.;,):s. ? (..... . a gr .g. . r; ; r 4 ,.4 ~ 2; ~ ' .M - . g . k[., h. i

• E

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4 w;:a.' f. - '. s :, - - ' '. -. L 5. e((. ,.( - t . g', s s ~ n . t, '4 s A.4 % -' - f, %,_ A,. ee% -..R [,p :".. ... *.. '. -,.;.s, .[.,,,, s .^.,....,: g e.... + 2 ,w m - y.

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k1' '. ,s 4%'8..' W. ('. J; '.[' + , a... ;.s 'e "-.,. - y}.,.,a. 3. ,..,[',y'_. y.. u-g Qy, 9 .e+ ,L j g A. 3 .y.y: y 3 %x 'e:e e; _: m _i - g, ;g T w, /, s.@ .. th.TN / b_O(v 7"f f O h., (j . p '.. h [ '. '( ye, f. 1000x Figure 24. SEM photograph of second Figure 2". EDS scan of " smeared" area in we " smeared" area on bolt. Figure 25. .., v. 7 1 2.< } [ f.,;.', f ',' 6 w...-;; '_%' j ; s. .a - kg.n ~ y;q.. w -; ff.g.;RN,.% -..y - :;?e -. f %.

/s

.T .4 .,%e k ?%g%/ 42,;,'DNMv4w4.,.[.Q.5 :f 1.,4r.y t h'- .,. [$)wg' d.[4 4y3,'*9.# g,n,.e. w' [ ' ' ^ -' '[. t $k f f 'f .? hf$ a ^ ll;; f* *. 4c. n y;w.d; g.q..? w.:q ch :: 4 y A 6. m ~ $d' :d[,MM.;r,.f G',g... 'q t,f-f a @$1 MM 2M*].Gr..;Q.;T!s.g*6.%}';'y.pR3 . g. ,c.. ': to,. ..,3. :. p Figure 26. WDS scan of ' smeared" area for Figure 27. WDS scan of smeared area for molchdenum. sulfur.

1 4 e 'U"" U.S. NUCLEAD KEGULATORY COMMISSION in " BIBLIOGRAPHIC DATA SHEET NUREG/CR-2993 BNL-NUREG-51594

4. TITLE AND SUBTtTLE (Add Volume No, of appeconate)

2. ILeave blank)

Examination of Failed Studs from No. 2 Steam Generator at the Maine Yankee Nuclear Power Station

3. RECIPIENT'S ACCESSION NO.

7. AUTHOR (S) 5 DATE REPORT COMPLE TED C.Czajkowiki M "'"

l " ^" July 1982

9. PERFORMING ORCANIZATION N AME AND MAILING ADDRESS //nclude 2,0 Codel DATE REPORT ISSUED Brookhaven National Laboratory "Te'b"ruary I "^1983 Upton, NY 1,1973 J

6. (Leave blank)

8. (Leave blank)

12. SPONSORING ORGANIZATION NAME AND MAILING ADDRESS (incluoe 2,0 Code /

10. PROJECT 4 TASK / WORK UNIT NO Division of Engineering Office of Nuclear Reactor Regulation

11. FIN NO.

U.S. Nuclear Regulatory Commission Washington, DC 20555 A3400

13. TYPE OF REPORT PE RIOD COV E RE D (Inclas.ve dates)

Technical

15. SUPPLEMENTARY NOTES

14. (Leave o/an* /

16.. ABSTMCT (200 words or lessl Three studs removed from service on the primary manway cover from steam generator #2 of the Maine Yankee station were sent to Brookhaven National Laboratory (BNL) for exanination. The examination consisted of visual / dye penetrant examination, optical metallography and Scanning Electron Microscopy / Energy Dispersive Spectroscopy (SEM/EDS) evaluation. One bolt was "through cracked" and its fracture face was generally trans-granular in nature with numerous secondary intergranular cracks. The report concludes that the environmentally assisted cracking of the stud was due to the interaction of the various lu'qvicants used with steam leaks associated with this manway cover. u I ?, M E Y'WORDS AND DOCUMENT AN ALYSIS 17a DESCRIPTORS lubricant corrosion threaded fastener degradation transgranular cracking 17b. IDENTIFIE RS OPE N E NDE D TE RMS 18 AV AIL ABILITY STATEMENT

19. SE CURITY CLASS IThrs reperr/

21 NO OF PAGE S Unclassified Unlimi ted 20 Sgi's*si N'e'["'" a S N RC Fortv 335 ste au ?}}