ML20199J228
| ML20199J228 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 01/29/1998 |
| From: | NORTHERN STATES POWER CO. |
| To: | |
| Shared Package | |
| ML20199J205 | List: |
| References | |
| NSP-26Q-302, NSP-26Q-302-R01, NSP-26Q-302-R1, NUDOCS 9802050264 | |
| Download: ML20199J228 (11) | |
Text
et m m 1me smenm iisenisassoc E; 1sismises m. ses ma rrRocrDRAL CALCULATION FRENo: NSP 26Q 302 Q%Q PACKAGE PROJECT No: NSP 26Q PROJECT NAME: Canopy Seal Weld Repairs for Prairie bland CLIENT: Northom States Power CALCULATION TrrLE: Evaluation of Limiting Flaws for Sauctural Adequacy in Canopy Seal Repairs at Prairie Isisad Nuclear Plant PROBLEM STATEMFET OR OBJECTIVE OF THE CALCULATION:
Demonstrate that stie through wall flaw size detectable by visual en=laarlon is less than the cridcal flaw stae for both axially and circumferentially oriented flaws.
Pmject Mgr. Preparer (s) &
Document Afflected Revision Description Approval Checker (s)
Revision Pages SI W & Signatures & l Date Date 0 1-7 IniM hsue
- HLG 1/28/9$ HLG 1/27/98 A0 A1 MLH 1/28/98 .
B0-Il4 CD C3 DO-D4 1
1-7 fn ,k psf cmqf$ fg }g )$j 29f W AO Al B0 - B4
- CO C3 DO-D4 .
i SIC-95-003, Rev.1 Page lof 2, 9002050264 980130 PDR ADOCK 050002 2
es m -30 15:47 STRUCTURAL INTEGRITY ASSOC INC
- 161 b HO.689 D03 L0 INTRODUCTION At the requent of the NRC and in support of the use of visual e.nmination rather than dye penetrant exarmnation of the completed weld oveday repairs to canopy seal welds at Prairie Island, Structural Integrity Associates (SI) perforrned several analyses to determine the critical -
flaw size in the repaimd laceden. De purpose of these analyses is to demonstrate that a through wall flaw could be detected by visual enmination having a size which is sufficiently smaller than the critical flaw size, thus apuring suf5cient safety margins. NSP will review the critical flaw aizes determined in this c=1~tmlon to cordirm that the resuhing sizes are detectable with margin by the visual technxtue.
2.0 GEOMETRY ne design georr.etry of the repair is illustrated in Figum 1. For the purpose of the present evaluation, the component was modeled as a pipe wth outaide radius equal to the distance from the drive centerline to the canopy seal weld (3.76 Irrha=) and wall thickness equal to the minimum anticipated overlay thicknec.s (0.36 inches), as shown on Figure 1. Thmugh wn!1 axial and cirrumferential flaws were evaluated, These geonceries are considend to be masonable representations of the actual design geometry, ne model geometries are shown in Figure 2.
3.0 APPLivn STRESSES For conservatism, the applied stress was assumed to act as a membrane stress at the Code allowable membrane stress magnitude (Pm = Sm). No distinction was made between the hoop and axial directions in this regard, althou8h realistically, the axial dimetion shouki be half of this value. Dased upon discusst=< with plant pmnnnel here t are no bending loads present.
Herefore, bending stresses were not considered.
Revision 0 1 Nyarer/Date HLoImas J/f{l/tt[97 Chosker/Dsse urn sama . ggpf,y
' ~
Fde No. NSP-260-302 Page 2 of 7
Ot/29/98 t5:47 STRUCTURAL. INTEGRITY ASSOC IHC o 16123307603 HQ.689 GB4 4.0 MATERIAI. PROPERTIES The allowable stress, Sm. was taken to be 16.2 kai at 650' F which is typical of 304 stainless steel.
The Alloy 625 to be used in the weld overisy repair has a significantly higher allowable stress at this temperamre so use of the stainless steel value is conservative. The flow stress for this component was taken as 3 Sm.
For linear elastic fracture inachanics evaluations, the Kc was takes as 135 kai [id, which is very conservative for this rnaterial at this teisi..i- (the weld rnetal will be applied using an automated gas shleided process).
5.0 ANALYrlCAL APPROACH Two analysis methodologies were employed. The limit load (net section collapse) method is considered most appropriate for evaluation of throu5h wall flaws in this very ductile material.
This method is bdkd in Appendix C of ASME Section XI. Por cornparison, linear clastic fracture mechanica (LEFM) methods were also applied. This approach is very conservative for 'b' this material, due to its ductile behavior.
$5[
a.
Four cases were studied. These were:
- l. Throughwallaxialflaw: Limitload.
- 2. Through wall axial flawt LEFM -
- 3. Through wall circumferential flaw: Limit load.
- 4. Through wall circumferential flaw: LEFM.
No Code safety margms were included in this evaluation, since the objective is to get a reasonable view of the relatienship between hele and critical flaw sizes.
Revision 0 1 Preparer /Date lu.G Imsa y[11/q[g Checkar/Date Mt,u inses pgffg File No. NSP-26Q.302 Page 3 of 7
24M2 19:e s u E n p rRITY ASSOC IHC
- 16123307603 NO.689 905
. The repults from each case are suruu M below.
6.0 RESULTS hurgh Wall AzlalFlaw Limit Lead 6.1 This case follows the methodology underlying ASME Seedon XI,IWB-3641 and Appendix C, The SI program pc CRACK [1] was used to perfonn the analysis. The pc-CRACK maulta are
- h-1 in A A to this report. %c conclusion is that an axial flaw c'ould be at least 4.6 laches long befors teading to incipient collapse %is is much longer than is physically achievable, since cracidng would be expected to be confined to tbc wc!d overlay material and vicinity, which, in the axial dhecdon, extends approulmately 1 inch.
6.2 Through Wall AxialFlaw: LEFM :. .
His analysis assumes that britde faihne is the operative mechanism. He pc CRACK program is used with this analysis. A fracture mesmaks tuodel of a through wall crack in a cyllader under intemal pressure was used, together with an assumed fraans toughness Kx:= 135 ksi E. He pc CRACK results are shown in Appendix B. The conclusion is that for this set of assumpdons, the critical flaw length is greater than SM inches.
6.3 Through Wall Circunderential Maw: IJanit Load '
This analysis used hand calculations using the methods of Se:: tion XI IA g=adir C. The SI program ANSC was also used to perform a separate analysis of the same configuration. The analysis assumed a through wall circumferential flaw, and %iaed the critical flaw length using limit load techniques. The conclusion is that such a flaw could be 12S' around the cylinder Revision 0 1 Preparer /Date in.o Imns y[),s/gdy Checker /Date ut.x inma j fg' g p
~
File No. NSP 26Q-302 Page 4 of 7
24M2 S9:cD eigr5gn ggggw ggf tic . isikrafsef Ws~e9 pos before reaching a cridcal size. This cormsponds to a flaw approximmly 8.4 inches long.
. Compyter output is included in Appendix C of this report. ,
6.4 Through WallCircunferentialFtwa LEFM This analysis assumed that the failure mode was luitle f allure. 'Ibe pc CRACK prograrn was used with a through wall circumferential flaw in a cylinder under remote tension fruture mechanics model. A Kec o 135 kai fin we. .nwvatively assumed. b conclusion of this acalysis was , hat the crideal flaw length for this set of assumptions was approximately 8.0 inches.
The computer output is included in Appendix D.
7.0 CONCLUSION
S b above results demonstrate that, under a variety of conservative assumptions, the critical flaw .
size predicted for the repair geornetry is in all cases signiM=dy longer than the flaw length which is expected to be detectable by a visual, examination under magnificatinn as proposed by NSP.
' U ,.
This will be confirmed by NSP. '
8.0 REFERENCES
- 1. StmeturalIntegrity Associates, ANSC, Version 2.0,1994. .
- 2. Structural Integrky ace *=, pc-CRACK, for Windows, Version 3.0, March 1997.
- 3. ASME Boiler and Pressure Vessel Code,Section XI,1989 Edition, No ddenda.
Revision 0 1 Preparer /Date m .c i m /9s /)Q 1/;9[gr Checker /Date MLH tt2ama fjggy File No. NSP-26Q.302 Page 5 of 7
01rd9 m 15:48 STRUCTURAL 1HTEGRITY ASSOC IRC E 16A23307603 30.689 P07
! k g M1 1
/
n .
l - - . . . , j ,,
i N
l \ 0.36'
\, .
l .
i i 7
U . .
O.38' 0.62* 0.38"
- l ,,,,
i I ,
CRDM !
k te0iM -
Notei; AddWonal material may be added to aks for fit up nw4dng i Figure 1 Revision G 1 Pn pam/Date HLG IMS8 M[)l[g9[gy Checker /Date M121 Inam /
[g File No. NSP-260 302 *E Page 6 of 7 i
G149m isi48 STRUCRM. INTEGRITY hSSOC IHC
- 6123307603 W.689 POS 8 e
- R -
- R j
- t = 0.36' 1
- t = 0.36" i e 8
. . I e i
- i i . .
i i e c i i i i i i .
l v l
. IAxw. , , ....---
-[. . . . !"C '
i
. i
. t 8 i
e i i i i e. .
i i i i . i i
i i . .
,l
,9,.
- , 'N -
,i, l- ;; -L s g g
_ Q .... Q Q.....Q '
- i R = 3.78"(actual) ,
Figure 2 Revision 0 1 1 Prepam/Date HLO ImS8 g[1)/79[9y Checkerroate uus uzes #gggp '
File No. NSP.26Q-302 Page 7 of 7 a - -
O e
ATTACHMENT 2
SUMMARY
OF CAMERA TESTING WELDING SERVICES INCORPORATED I
ISI-IST\SEALREQ3 DOC J
a
lll Welding Services Inc.
Ec"acoa oSoEmn nlflaiiny"** .
Mr. Dick Ccoper June 21,1995 Northern States Power Company 1717 Wakonade Drive East Welch,MN 55089 FAX: 612-330-7603
SUBJECT:
Prairic Island Nuclear Plant WSt Reference No.: 35049-2
DearMr. Cooper:
Per your request, we have performed several tests to evaluate th system used in the performance of the wcld repair ofPrairie Island's CRD this testing is to provide data to be used by NSP to evaluate camera for the the adequ i
performed as a safety related procedure. He testi 1.make The video and model as thefmnt end system used of the WSI weld head was con on site.
- 2. A mockup of a canopy seal housing similar in configuration s to overleyed in a similar conUgaration as the repair performed at the site.
A .0005 inch the weld overlay on the housing. diameter wire and a .001 in J. illumination.
Tbc two wires were fdmed using the weld head front ng forend, and th
- 4. the WSl's site QC representative, Gary Caul, reviewed the tape surface of the weld. on and was A copy of the tape, sarnples of the two wires used, and additional camera are included with this letter for your review. P! case let rue know .
ifyou nee
%y,&M Sincerel Pedro E. Amador Senior Project Manager m a.1 ooc I
4 J
s ATTACHMENT 3 i I
i CONTROL ROD LOCATIONS SYSTEM DESCRIPTION FIGURE 86 2 i
1 I
l l
d t
L i
4 0 .
3 1
- l i.
a
- l v
ISNST\$EALREQ3 DOC
_ . _ . , , , . . _ - . ...,_ -.._ _ -.--_ _. , - - . - . = . . - _ , . _ - - - . . . . . _ . - . . _ . - - - . _ _
1 2 3 4 5 6 7 8 9 10 11 12 03 I
, l I .
4____ __ ___ __ _____
B---- --------
A A c---- --- -
Bs D As o- --
C C e--- -
Bs As F--- A B Bl A o - - -- D C D n---
A B B A i----
Bs As a---- C C x- - - - - - -
As D Bs I
?
t------- A A u--------------
i
- 00 LOCArsones asvrso m e B5-2 1
_ _ _ _ _ _ _ _ _ -