ML20058H365
| ML20058H365 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/08/1990 |
| From: | Fay C WISCONSIN ELECTRIC POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| CON-NRC-90-113 VPNPD-90-462, NUDOCS 9011150219 | |
| Download: ML20058H365 (8) | |
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Y Electnc l)
[.y 4 POWER COMPANY i
!A 231 W McNoon, Po Box 2046 M!woukee wi S3201 '
(414)221-2345
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c NRC 113 -
'l ri Novemb'er 8, 1990
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h l Document: Control Desk l
U. S.1
. NUCLEAR REGULATORY. COMMISSION
. Maill Station. P1-137:
i xWashington,;D.C., 20555 aNk:
cGentlemen2.
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E' QQCKET NO.- 50-301;.
j E M, UNIT '2 "A" STEAM < GENERATOR GIRTH WET.h INDICATION
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/l lhjPOINTLBEACH' NUCLEAR' PLANT; UNIT'2, j
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'4 -* l,Lo'n-OctoberJ30,01990,'a; conference: call between:WE and the NRC was t
l 4 imade<to0 discuss the? indications identifiedein-the Unit 2.."A"; steam.
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.'*JgeneratorT.transitirn cone weld.., As discussed,.the attachment to L!
thist etter. prov.i.;es
--'a'.~ description 'of the; indications and their l
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'N W ievaluatio'n.' '
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o ItIlsInoted/that noneiof!the in'dications-are. surface flaws.
All of-9? ' ?!-
'.4 Q these? flaws lareishown to bel acceptable /forfcontinued operationlinf y..!c'taccordance with theLmethods'.of IWB-36001of -ASME Section.XI.-; Based' S.3 W,?upon:this evaluation,JweLdo"notHconsiderltheseLindications'to;be a.
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.- l i An finformali copy of Lt.hisIs, letter and' its -attachments 1were telecopied.
- W 3htoiMr.1Samworth,on November'7,T1990. <IfLfurther details are f]
, $ M '.h r e q u i r e d, Econtact'MessrsV G.T R'iSherwood or J. lF. Kohlwey ' at l f
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](414 ) ~155-2321.
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.NRC ResidentfInspector 7$
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XNRC-. Regional' Administrator, Region III
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i UNIT 2 "A" STEAM GENERATOR ITANSITION CONE
-I GIRTH WELD INDICATION
)
I.
INTRODUCTION'
.j1 Recent industry experience has shown that the upper steam drum shell to transition cone weld, on Westinghouse steam generators, has been susceptible to cracking on the inside surface. Recently, Indian Point 2 7
and Eion 1-and 2 have reported cracking of the weld at the inside surface, which required repair.
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The steam generator upper shell to transition cone girth weld is a class 2, category C-A vessel weld.
Based on the requirements of table ll LIWC-2500-1,~of.the 1977/ summer '79 edition / addenda of ASME XI, one upper 1
.shell~tt transition cone weld is examined.once every ten year interval.
4 3,.
Based on current-industry experience, we chose to inspect the "A" steam p;,
-_generatorfgirth weld a second tkne during the second ten year interval.
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~The "B"! steam generator girth' weld was examined in11989, with_ acceptable a
m' results.
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.Duringsthe Falle.1990 Unit 2 Refueling Outage, the-"A" steam generator-l+,
= m, k,[
pper shell.to trans'ition cons girth. weld, SG-A-4, was: examined.
The.
examination performed.by: BBASCO revealed. eleven '(11). embedded m(
Jindications-near~the' fusion zone of the weld. Six indications were
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Lwithin the acceptanceflimits-of m.icle IWB-3511.
Class: 1 acceptance i}, h'
- 11 hits.were applied
- Eo,the indications as allowed per Article IWC-3000 j
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.t in +he'1977/579 edition / addenda of ASME XI.
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}l Five-.indicationsiwere found to be;outside the acceptance limits'of
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h fArticle IWB-35111and-were evaluated in accordance'with IWB-3600, using
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linear elastic fracture mechanics. Those indications were evaluated and j,
found acceptable for continued operation.
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- II..
EXAMINATION METHOD y
one hundred percent of weld SG-A-4 was exam.,ied utilizing a 1/2"xl",
2.25 MHE transducer for detection. The weld was scanned from both sides using 45* and 60' angles.
Beam spread of this transducer was 9.5*.
Sising of indications was performed using a 1" round, 2.25 MHZ transducere, with 45' and 60' angles.
Beam spread for this transducer 3-i was 6.5'.
All indications that were 250% DAC were sized using the 1/2 max. mum
. amplitude technique.. Since all indications were <100% DAc, this sizing method-is more conservatt.ve that the code technique which would require sizing indications to 50%'ef DAC.
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III.- EXAMINATION [RESULTS.
Elevenu(11) indications, as shown on Attachment 1, were ioentified-
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[within the. inner 1/3 of the-weld volume. The indications were plotted 1
6h.andLshowntobesubsurface. Attachment 1 lists all the pertinent Ldimensionsfassociated with each' indication for evaluation purposes.
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[To confirm;that the-indications: closent.to the inside surf ace were embedded,'a visual exam.and.a magnetic-particle test'were performed on
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.;the inside, surface.,'No surface ~ indications <were noted, nor was there l,a 6;
any evidence of. pitting.~ All of the indications can be clap ~kfied as.
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Lsubsurface and' embedded.
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'IV.-
EVALUATION OF RESULTS fi-H
.o All,of.the indications noted are acceptable in accordance with Article
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IWB-3511"with the-exception of the indications at locations 253.5",
- 260.5",'264",'267.5", and 356."
Those 5-indications were evaluated by lWestinghou'se' Electric Company and found to be acceptable for continued f.'
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' operation with linear elastic fracture mechanics as permitted by
-IWB-3600 of ASME XI.
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' Attachment 2 is a flaw evaluation chart, developed by Westinghouse, to
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evaluate' indications in the region of the upper shell to transition cone I
girth weld, of the Point Beach Nuclear Plant steam generators. The g
indications at'the locations of concern were plotted on the chart and' h.
'are'in regions that are acceptable for continued operation.
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- is a table of actual. material properties for the Unit 2 u
steam generator girth welds and adjoining base metals.
Material properties more conservative ~than those actually used in the mj JPoint Beach Unit 2 steam generators were assumed in the development of Yl theIflaw evaluation charts..Therefore the flaw evaluation chart in
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" Attachment 2 conservatively bounds the fra:ture toughness pr.
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thefUnit 2 steam generator materials.
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- Construction radiographs were reviewed and found to be free of dMi
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4 A6p p,W,q indications in the areas where UT indications were observed.
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'IA?l983, Southwest Research, Institute-(SWRI)Lperformed a'UT exam:of weld =
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go.A-4 and had determined that there was no recordable indications at-ev
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..that time. During the 1990 exam of weld SG-A-4, the' examination by.SWRI.
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'was repeated by EBASCO, utilizing similar1 techniques and transducers. 'A' j
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1/2 round, 2.25 MHZ-' transducer with 45', and 60* : angles; was used. ' All ;
ro;;f{ 'u t_ indications could be seen at less than the code recording level with'the y.
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&,I 'g 1/2" round,' 2.25 ' MHZ transducer - (i.o
.it DAC).
Since the indications-1
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)h were seen at-less than 50% DAC, siziro e suldinotEbe specifically n
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required by the code. This-would explain why no' recordable indications.
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were found in 1983..
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CONCLUSION i
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4 The' indications found in a steam generator girth weld, SG-A-4, are embedded and appear to be small areas of embedded slag.
Based on an evaluation of the indications in accordance with IWB-3600, "A"
steam generator can resume operation. A successive examy as required by IWC-2420b will be performed during the next-inspection period of weld
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SG-h-4.
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ATTACHMENT 1 UNIT 2 "A" STEAM GENERATOR OIRTH WELD SG-A-4 INDICATIONS 2
l LOCATION 2a 1
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Y A/T CODE S/G ALLOW ACCEPT (Arimuth) 78"
.23
.75" 3.7
.253 3.11 _
.76 1.0 3.22%
Y 81" 3.7 1.0 2.6%
Y 253.5"
.42 1.3" 3.85
.162 5.45%
.75 1.0 3.30%
N 260.5"
.34 1.1" 3.85 1.54-4.4%
.8" 1.0 3.23%
N 264"
.42 1.9" 3.85
.11 5.45%
.89" 1.0 2.96%
N 267.5"
.34 1.4" 3.85
.12 4.4%
.68" 1.0 3.02%
N 356"
.328
.6" 3.7
.273 4.43%
.27 1.0 4.33%
N I
358"
.287 1.6" 3.7
.058 2.5%
.18 1.0 2.82%
Y 358"
.24-
.7"'
3.7
.10 1.89%
1.45 1.0 2.90%
Y 3
361"
.235
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.236-2.9%
.48' 1.0 3.96%
Y 388"
.187
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3.8
.235 2.47%
.14 1.0 3.95%
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Table IW8-3511-1.1977/S79 Edition / Addenda ASME XI 2-k All indications are'aubsurface.
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ATTACHMENT 2 4
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4 SURFACE / EMBEDDED L
FLAW DEMARCATION e
UNE.
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MP 0 W 0.08 o 0.10s 0.16 '.
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- DISTANCE FROM SURFACE' t )
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Flaw avaluation. Chart for Circumferential ambedded Flaws in the Upper shell to cone Wold Region: Point Beach Unit 2 ** PRE 1,IMINARY**'
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ATTACHMENT 3 TABLE 2-3 MATERIAL PROPERTIES FOR UPPER SHELL - CONE REGION POINT BEACH NUC13AR PLANT UNIT 2 MATERIAL CHARPY LOCATION.
TYPE-VALUES LATERIAL RTgy (10'F)
EXPANSION (ft-lb)
(Inches)
Cone. materials, SC/A Heat C3139-3 SA302B.
111,112,116 Not 10'F
-, d ':
lleat C3139-3.
SA302B 111,112,116 Available 10*F Heat C3139-5 SA302B 113,133,110 10'F f
Upper shell' materials
-SC/A :
, Heat 7073 SA309" 96,92,102 Not 10*F Heat:7073-2
.SA3 bit 104,129,95 Available 10*F
' Heat 7073-2*
SA302B 41, 3 5, '> 0 -
30'F-Cone materials,-:SG/B
. SA302B
. 137,104,107 Not-10*F
' Heat.C3139-4
~rleat - C3139-4' SA302B
.137'104,3V1 Available 10'F
- g
= Heat B7121-2 SA302B
--135,113,'1/2 10*F
' Upper;shell' materials-
' ~ Heat'B7201-4
'SA302B 103,99,85 Available 10'F SG/B..
. Heat.A2699-3 SA302B-71,71,87 Not 10'F
__ 0
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lWald-Shielded Metal CH
' Arc-3-
(Wire 'L57678-
- 102,110,106,107,99**
Not 10'F
- - WLre A192620' 113,123,102,118,157 Available
-10*F Wire / 601137
'97,86,79,95,951 10'F p.
Wire' 80D634 89,101,102 10*F' pp,
y (testo performed after reheat treating (stress relieved at 1125'F for
>
- 1-
{r 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br />, furnaco cooled) c, n,l Lwelds stress relieved 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> e 1150'F
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