ML20209G440
| ML20209G440 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/17/1987 |
| From: | Cofie N, Froehlich C NUTECH ENGINEERS, INC. |
| To: | |
| Shared Package | |
| ML20209G412 | List: |
| References | |
| CEC-73-203, CEC-73-203-R, CEC-73-203-R00, NUDOCS 8702050367 | |
| Download: ML20209G440 (57) | |
Text
{{#Wiki_filter:CEC-73-203 Revision 0 I January 1987 CEC 073.0203 l I EVALUATION AND DISPOSITION OF FLAWS AT QUAD CITIES NUCLEAR POWER PLANT UNIT 2 (1986 OUTAGE) Prepared for: Commonwealth Edison Company Prepared by: NUTECH Engineers I
- Reviewed by
- Issued by:
N.G. Cofie, Ph.D. C. H. Froehlich, P.E. Project Engineer Project Manager I Approved by: I
- Date: AN. 3 C. H. Froehlich, P.E.
Engineering Manager I 8702050367 870119 PDR ADOCK 05000265 MW @C G PDR I
REVISION CONTROL SHEET TITLE: Evaluation and Disposition DOCUMENT FILE NUMBER: CEC 073.0203 I of Flaws at Quad Cities Nuclear Power Plant Unit 2
'(1986 Outage) - CEC-73-203 A/4 C-I N. G. rnfi n / Principal Consri tant N AME / TITLE INITIALS M. E. Kleinsmith/ Consultant I NdbdN NAME/ TITLE INITIALS W
I C. H. Froehlich/ Staff Engineer N AME / TITLE INITIALS I N AME / TITLE INITI ALS I AFFECTED PAGE(S) DOC REV PREPARED BY / DATE ACCURACY CHECK BY / DATE CHECK BY / DATE CRITERIA REMARKS tv-vit 0 NGC llf0 7 CNN fet MlW OA br NEN III1]T1 Ifrt/g1 1.1 - 1.9 0 2.1 - 2.3 0 3.1 - l 3.8 0 4.1 - 4.11 0 5.1 - 5.12 0 l 6.1 & 6.2 0 lf If I 7.1 & 9f 7.2 0 #4c ///7/8 7 C476eNEK CW96cHElf-
- Ilnl91 I/I1/87 1 0 OE5IY'IY'I one I/*1/67 rosoc Ift1f97 PAGE OF I O E P 3 3.1.1
i CERTIFICATION BY REGISTERED PROFESSIONAL ENGINEER I I hereby certify that this document and the calculations contain-ed herein were prepared under my direct supervision and have been reviewed by me and to the best of my knowledge are correct and complete. I I further certify that, to the best of my knowledge, design margins required by the original Code of Construction have not been reduced as a result of the activities addressed herein. I am a duly Registered Professional Engineer under the I laws of the State of California and am competent to review this document. Certified by: I +%o' 4 daQ k' Adlal C. H. Froehlich, P.E. d % Registered Professional Engineer I ;d No.27862
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State of California Registration No. C 027862 l Qg g Date: JkN.1.7s1hh7 I hereby certify that this document and the calculations contained I herein were reviewed by me and to the best of my knowledge are correct and complete. I further certify that, to the best of my knowledge, design margins required by the original Code of Construc-tion have not been reduced as a result of the activities addressed herein. I am a duly Registered Professional Engineer under the laws of the State of Illinois and am competent to review this document. Certified by:
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[I._S. Herlekar I i Tq REGISTEPED i x 3 I, V $,'.,,,.st$jf e,, CF ,,/M/f f Registered Professional State of Illinois Engineer Registration No. 062-041111 4' .h"/.
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Date: 1AN . k(# ) 1Db7 I I CEC-73-203 Revision 0 111 sleCh I
Page { LIST OF TABLES V I L LIST OF FIGURES vii
1.0 INTRODUCTION
1.1 5 2.0 REPAIR DESCRIPTION 2.1 3.0 EVALUATION CRITERIA { 3.1 3.1 IHSI-Mitigated Weld Evaluation 3.1 p 3.2 Weld Overlay Repair Evaluation 3.3 L 4.0 APPLIED AND RESIDUAL STRESSES 4.1 {' 4.1 4.2 Primary Stresses Secondary Stresses 4.1 4.1 5.0 EVALUATION METHODS AND RESULTS 5.1 5.1 IHSI-Mitigated Welds 5.1 5.2 Overlay-Repaired Welds 5.2 6.0
SUMMARY
AND CONCLUSIONS 6.1 {
7.0 REFERENCES
7.1 APPENDIX A - Full-Structural Weld Overlay [ Repair Calculation for Weld 02A-S10 A.0 [ [ [ [ CEC-73-203 iv Revision 0 { nutech V --- - - - - - - - -
e L LIST OF TABLES Number Title Page r 1.0-1 Comparison and Description - Flaws Overlay- 1.4 I Repaired Fall 1983 Outage / Built-Up Fall 1986 Outage - Quad Cities Unit 2 1 1.0-2 Comparison and Description - Flaws IHSI- 1.5 Mitigated Fall 1983 Outage / Overlay-Repaired Spring 1985 Outage / Built-Up Fall 1986 Outage - Quad Cities Unit 2 1.0-3 Comparison and Description - Flaws IHSI- 1.6 Mitigated Fall 1983 Outage / Overlay-Repaired Fall 1986 Outage - Quad Cities Unit 2 1.0-4 Comparison and Description - Flaws IHSI- 1.7 { Mitigated Fall 1983 Outage - Quad Cities Unit 2 3.2-1 Expanded Allowable End-of-Evaluation Period 3.6 Flaw Depth-to-Thickness Ratio for Circum-ferential Flaws - Normal Operating Conditions j 3.2-2 Leakage Barrier Repair Criteria for 3.7 Axial Flaws j 4.1-1 Quad Cities Unit 2 - Primary and 4.4 Thermal Expansion Axial Stresses 4.2-1 Quad Cities Unit 2 - Total As-Built 4.5 l Weld Overlay Shrinkages 4.2-2 Quad Cities Unit 2 - Weld Overlay Repair 4.6 l Shrinkage Axial Stresses 5.1-1 Pipe and Flaw Geometric Details - 5.4 Circumferentially Flawed IHSI-Mitigated Welds I 5.1-2 Circumferentially Flawed IHSI-Mitigated Welds - Predicted End-of-Cycle Flaw Depths 5.5 5.1-3 Circumferentially Flawed IHSI-Mitigated 5.6 Welds - Generic Letter 84-ll/ Table IWB-3641-1 Predicted vs. Allowable Flaw Depth Ratios 5.1-4 Circumferential Flawed IHSI-Mitigated Welds 5.7
- Table IWB-3641-5 Predicted vs. Allowable Flaw Depth Ratios CEC-73-203 v Revision 0 nutech
) LIST OF TABLES (Concluded) Number Title Page 5.1-5 Circumferentially Flawed IHSI-Mitiga- 5.8 ted Welds - Generic Letter 84-11 Limit Moment Allowable vs. Actual Flaw Length 5.2-1 Pipe and Flaw Geometric Details - 5.9 Overlay-Repaired Welds m 5.2-2 Applied vs. Allowable Stress Ratios - 5.10 r' Overlay-Repaired Welds L 5.2-3 Overlay-Repaired Welds - Pipe and Flaw 5.11 Geometric Details - Axially Flawed Welds { 5.2-4 Overlay-Repaired Welds - Applied vs. 5.12 r Allowable Stress Ratios - Axially L Flawed Welds [ [ ( CEC-73-203 vi ( Revision 0 nutech
L LIST OF FIGURES I H Number Title Page [ 1.0-1 Quad Cities Unit 2 - Flawed Weld Locations - 1.8 Recirculation System Loop "A" 1.0-2 Quad Cities Unit 2 - Flawed Weld Locations - 1.9 Recirculation System Loop "B" 2.0-1 Quad Cities Unit 2 - Weld overlay Repair 2.3 Details - Fall 1986 Outage
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3.1-1 NUREG-1061, Volume 1 - Stress-Corrosion 3.5 Crack Growth Rates 3.2-1 Source Equations for Allowable End-of- 3.8 Evaluation Period Flaw Depth-to-Thickness ( Ratios for Circumferential Flaws 4.2-1 Quad Cities Unit 2 - Thermal Transients 4.7 4.2-2 Quad Cities Unit 2 - Through-Wall Temperature 4.8 Gradients 4.2-3 Pre- and Post-IHSI Through-Wall Residual 4.9 Stress Distributions for 12" NPS Pipes 4.2-4 Pre- and Post-IHSI Through-Wall Residual 4.10 Stress Distributions for 28" NPS Pipes 4.2-5 Under-the-overlay Through-Wall Residual 4.11 Stress Distributions ( [ ( { [ CEC-73-203 vil Revision 0 nutech {
L r L
1.0 INTRODUCTION
F, 1 This report summarizes analyscs performed by NUTECil to evaluate flaw indications in the Reactor Recirculation and Shut Down Cooling systems at Commonwealth Edison's Quad Cities Nuclear Power Plant Unit 2. Ultrasonic (UT) examinations of welds in these systems since 1983 have identified flaws judged to be intergranular stress corrosion cracking (IGSCC) in the vicinity of a total of - twenty-seven welds. Twenty-two flawed welds were - [ identified during the Fall 1983 outage. One of these welds (12S-S27) was removed and replaced (spool piece { replacement). Two flawed welds were identified during the Spring 1985 outage. Five additional flawed welds " were identified during the Fall 1986 outage. The location of these welds are shown in Figures 1.0-1 and 1.0-2. In addition to the twenty-two flawed welds identified h during the Fall 1983 outage, IGSCC was originally thought to have occurred at one other weld. However, a { geometric discontinuity was identified through the use of a core sample at this weld (02BS-S12) in 1983. Also, one of the welds found cracked in 1983 (02BS-F14) was identified as uncracked in 1986 (inside diameter root geometry). The design of previous weld overlay repairs and the [ analysis of IHSI-mitigated weld flaws discovered during the Fall 1983 and Spring 1985 outages at Quad Cities { Unit 2 are described in NUTECH Reports COM-75-002 (Reference 1) and CEC-20-013 (Reference 2). These previous weld overlay repairs were upgraded to full-structural (standard) weld overlays with adequate surface finish to permit inspection of the weld overlay CEC-73-203 1.1 ( Revision 0 nutech
l l and part of the original pipe wall. All new weld overlay repairs implemented during the Fall 1986 outage were designed as full-structural overlays. Tables 1.0-1 through 1.0-4 present descriptions of the IGSCC flaw indications at Quad Cities Unit 2. Table 1.0-1 describes flaws in the nine welds which were i overlay-repaired during the Fall 1983 outage and built-up to full-structural overlays during the Fall 1986 outage. Table 1.0-2 describes flaws in five welds which I were shown to be acceptable with only induction heating stress improvement (IHSI) mitigation during the Fall j 1983 outage, but were overlay-repaired during the Spring 1985 outage and built-up to full-structural overlays during the Fall 1986 outage. Table 1.0-3 presents six welds which required overlay-repair during the Fall 1986 I l outage. Four of the welds had no reportable indications in 1983 and 1985. The other two welds were analyzed and justified for continued operation with only IHSI mitiga-l tion in 1983 and 1985. Table 1.0-4 describes flaws in eight welds which were shown to be acceptable with only l IHSI mitigation implemented during the Fall 1983 outage. Weld 02BS-F14 was evaluated as having only l inside diameter:. root geometry in 1986. we dments t uad C ties Un t 2 are 11 r et 1 (standard) designs (based upon an assumed 100% through-original pipe wall depth-by-360' length circumferential flaw), the 1986 ultrasonic examination (UT) results reported in Tables 1.0-1 through 1.0-3 only include flaws drawn up into the overlay repair by steam blow-outs during overlay implementation. All of the reported t indications were observed using EPRI qualified manual UT techniques except for Wold 02A-S10. Because of high
, CEC-73-203 1.2 Revision 0 nutech
t noise levels encountered in this weld's overlay during manual examination, EPRI qualified automated UT techniques were employed. These techniques resulted in remaining ligament values greater than those observed using the manual techniques. ^ The purpose of this report is to demonstrate that the - original design margins of safety for the flawed welds L at Quad Cities Unit 2 have not been degraded by the presence of IGSCC flaw indications or repairs. In addition, it will be demonstrated that existing weld overlay repairs are adequately sized to meet anticipated ] changes to regulatory requirements. Section 2.0 presento a general description of the overlay repairs and build-ups performed at Quad Cities Unit 2 during the Fall 1986 outage. Sections 3.0 and 4.0 present the evaluation criteria and loads used in the analysis of overlay-repaired and IHSI-mitigated weld flaws. Section 5.0 presents the evaluation methods and results. I Sections 6.0 and 7.0 present a summary of conclusions and the references used in the evaluation. l Appendix A contains a full-structural weld overlay repair calculation for Weld 02A-S10. This calculation is provided to demonstrate that the remaining ligament values over axial flaws in Weld 02A-S10 meet full-structural weld overlay repair criteria. This compari-son is very conservative in light of the differences in l applied loads, fracture mechanics behavior, and IGSCC-character of axial versus circumferential flaws. l CEC-73-203 1.3 Revision 0 nutech I
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@hO ow COMPARISON AND DESCRIPTION FLAWS OVERLAY-REPAIRED FALL 1983 OUTAGE /
BUILT-UP FALL 1986 OUTAGE QUAD CITIES UNIT 2 1906 NTASL-I N 3 N TAEE 1985 IUTAIE (FBIR POST-NIR IT ElminAlltal IRIEN- MIEN- IRIEN-CouFIGURATION - IuSTEM KPIN TAllN LICATIIR LEETH REPIN TAI!Ou LKAilIN LEMiu IEPIN TAllIN LKATIIR l uELO NG. PIPE SIZE UPSIEM LENGIN I* 301 CIK. PIPE S!K =T leIPECTER ----MI FLANS 15 UELS MEAV REPAlt-
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PIPE 364 K S. 151 ClK. UPSTR.SIK ---WT IIEPECTE: --W FLAME tu WELS MEAT KPAIR--- 02F-F6 12* PIPE Ettou P!PE 2-114' 321 ClK. PIPE SIK T luBPECTER -MB FlauE IN ELB OWEEAT KPAlt-- 026-S3 12' PIPE 15* 151 ClK. PIPE SIE =T tulPECTES ----III FLAME IN ELI IVEKAV KPhiR--- 02J-F6 12* SuEEPOLET ELSIN 112* 101 AllE ELIIN S!K Of luBPECTER ---WI FlauE IN ELS OWERAY BEPAIR-02AS-59 28* VKVE I* 91 ClK. ELIAN $1K =T IMPECTE: -----NB Flaus IN ELS SWERAV KPAlt--- 0245-59 29' VEVE EL30u VEVE EL90s 11* 231 ClK. ELIIM SIK =I IlWECTER -----W FlauE IN ELD SWEEAV KPAlt-02AS-59 28* Ellet 12* 131 CIK. ELIIN SIK =i IMPECTES -5 FLAuE IN ELI SWEEAT IEPAlt-- 02AS-59 20' VKVE 12* 401 ClK. ELIgu IIK :T IMPECTER ----NB FlauS lu ELE OUEEAT KPelt--- 0235-53 28' Ettou PIPE 360 KE. 161 CIK. PIPE SIK T II P ECTE: -----No FLAME IN NELI OVE R AY REPAIR- - 02BS-F7 29' VKVE PIPE IT* 391 CIRC. ELIIu SIM :T IMPECTER -m FLAUE IN uELI OWEKAV KPAlt-- 0280-56 25' ELSON PIPE Ett0u P!PE 1-114* 641 A!!E ELBlu SlK =T IMPECTEI -----MI Flaul IN ELB OWERAY KPAlt-- e2bD-56 20* C ioS-ri 2r TEE Pin 6- ut CiK. PIPE SiK - -mi imPECTE. -m rtms in Ett MKu EPu - et C) O 3*
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PIPE PIPE = K PORTAALE I M ICATIONE l' III CIK. IFSTREM -----50 FLAME tu uELI OYEKAY KPAlt-42E-F6A 12* 02E46A 12' PIPE PIPE = KPORIAILE luBICAileus ul Ill' 111 AllK 112* 141 CIK. IPSTREM -----ug FLAuS In UELI OYEKAY REPAlt-- 42E46A 12* PIPE PIPE = K FORIABLE IMICAllINE 42E-f64 12* PIPE PIPE = K PIRIAOLE I M ICAila 5 ul 8.2* 131 MIK ELBeu PIPE l-l/2* 301 ClK. ELBW SlK 3-II2* Set ClK. ELION SIK ----50 FLAuS In IELS OVERAY MPAlt-- 02u-53 12* 829-53 12* ELB05 FIPE l' 131 ClK. PIPE SIK 2' 651 ClK. PIPE SIN -m FLaut lu KLB OWERAI KPals-- 82u-53 12* ELBIN PIPE 7/I' 701 MIK PIPE SIK ----us FLAUS lu KLB OWEKAf REPAlt-- 02u-F7 12* SuEEPILIT PIPE 4-1/2* L KI IF FJSI: 7-1/2* IMI ClK. Sur. SlK --ug FLAuS lu WELB OYEKAf KPAlt-- 27' TDIK 131 ClK. ELBON SI E 50' 261 IIM. ClK. ELIEW $1K -----M FLAuS lu uELB DVERAY IIEPAlt-- 0245-54 28' ELION PIPE ELItu 4* 111 ClK. PIPE SIK -----uD FLAUS lu uELI DUEKAf KPAlt--- l 0245-54 28' PIPE l ClK. PIPE SIK ---50 FLAuS lu KLB OYEKAf KPAlt--- 10S-F5 20' YRVE PIPE 3-l/2* 181 CIK. PIPE SIK 9' til l 20* VRVE PIPE t* 121 CIK. PIPE $1K 10* ITI ClK. PIPE SIK -uS FLAuS In WELI OYEK4f KPAlt- ! 105-F5 105-F5 20* VKvE PIPE 3' 13I ClK. PIPE $1K - uS FLAuS 15 UELI OVE K AY M PAlt - - C e+- 1 l [) O 7
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u F L 2.0 REPAIR DESCRIPTION The weld overlay repairs implemented at Quad Cities Unit I 2 during the Fall 1986 outage can be placed into two categories. The first category is made up of previous l weld overlays from the Fall 1983 and Spring 1985 outages that were built-up to meet full-structural requirements and to enable adequate surface finishing for NDE of the overlays. The second category consists of new weld overlays that were applied during the 1986 outage. 1 For both categories, repairs have been made by { increasing the pipe wall thickness through the deposi-tion of weld metal 360* around and to either side of the j existing weld. The weld-deposited band provides addi-tional wall thickness to restore the original Code design safety margin. In addition, the welding process f I produces a strong compressive residual stress pattern on the inside portion of the pipe wall, which prevents further crack growth. The deposited weld metal is Type 308L, with controlled delta ferrite content so as to be l resistant to propagation of IGSCC. As-built information for all overlays is shown in Figure 2.0-1. 1 The nondestructive examination (NDE) of each weld j overlay repair applied in 1986 consisted of: 1
- 1. Surface examination of the existing pipe surface at new weld overlay repair locations by the liquid-penetrant testing (PT) technique in accordance with l ASME Section XI.
- 2) Delta ferrite content measurement of the first layer of new overlays or first layer of an existing overlay to increase its length.
CEC-73-203 2.1 Revision 0 nutech
E F L 3) Enhanced visual examination of the first weld overlay layer for evidence of IGSCC flaws for new [ and built-up overlays (discoloration, porosity, etc.).
- 4) Surface examination of the completed weld overlay by the PT technique in accordance with ASME Section x1.
- 5) Volumetric examination of the completed weld over-lay by the ultrasonic testing (UT) technique developed by EPRI.
E F L._ E E E [ [ [ CEC-73-203 2.2 Revision 0 nutech
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, THICKNESS I q WELD PATENTED
( Weld As-Built Thickness (in.) ID Upstream / Downstream As-Built Length (in.,) r 02C-S3 0.391/0.355 4.375 L 02D-F6 (1)/0.329 4.0 02E-F6A 0.314/0.373 4.5' 02F-F6 0.355/0.392 4.25 { 02G-S3 0.307/0.313 4.375 02J-F6 0.228/0.372 3.75 02K-S3 0.298/0.316 4.0 p 02K-S4 0.309/0.329 4.086 L 02M-F7 0.300/0.512 3.75 02M-S3 0.479/0.331 4.5 10S-F1 (1)/0.494 4.25 [ 10S-F5 02A-S10 (1)/0.543 0.677/0.474(2) 3.75 5.0 02B-S9 0.496/0.401 5.0 L 02AS-S4 0.451/0.504 8.5 02AS-S9 (1)/0.488 4.5 02BD-S6 0.530/0.670 8.0 02BS-F2 0.57/0.508 9.0 02BS-F7 (1)/0.484 7.25 02BS-S3 0.492/0.495 8.25 Notes:
- 1. Readings could not be taken due to geometry.
- 2. Includes low delta ferrite first layer thickness of 0.053".
( Figure 2.0-1 QUAD CITIES UNIT 2 WELD OVERLAY REPAIR DETAILS [ FALL 1986 OUTAGE CEC-73-203 2.3 Revision 0 nutech
I 3.0 EVALUATION CRITERIA 3.1 IHSI-Mitigated Weld Evaluation The following criteria were used by NUTECH during the current evaluation to justify further operation of Quad Cities Unit 2 with the detected flaws without weld overlay repair (i.e., IGSCC mitigation by the IHSI process):
- 1. The beginning-of-fuel cycle (evaluation period) bounding flaw size used in the analysis was the as-measured flaw depth by 360* circumferential length (conservative).
2. I The prediction of end-of-fuel cycle (evaluation period) flaw size was based upon a conservative IGSCC crack growth correlation which closely agrees with the NRR curve presented in Figure 3.1-1 from NUREG-1061, Volume 1 (Reference 3) using a combina-tion of dead weight, internal pressure, differen- , tial thermal expansion, and weld overlay shrinkage l stresses (caused by weld overlay repair of other welds in the piping system).
- 3. The calculation of IGSCC flaw growth was based upon conservative post-IHSI butt weld through-wall resi-dual stress distributions.
- 4. As currently required by USNRC Generic Letter 84-11 (Reference 4), the predicted end-of-fuel cycle (evaluation period) flaw size was compared to 2/3 of the ASME Section XI (Reference 5) Table IWB-CEC-73-203 3.1 Revision 0 nutech I
I 3641-1 allowable flaw depth values for a combina-tion of dead weight, internal pressure, and seismic stresses.
- 5. In accordance with Generic Letter 84-11, limit load analyses were performed on the IHSI-mitigated welds to ensure that the applied loads will not cause net section plastic collapse if the existing flaws are assumed to be 100% through-wall over their measured length. The limit moment, Mg, was determined by the expression:
2 1 Mg =4 art g (cos Y 7 sin 0) (from Reference 3) j I where: R is the mean pipe radius, t is the pipe wall thickness, e = half crack angle, 1 w Axial load y= 2 e+2 2nRo t ' and og is the flow streks. I 6. Because the allowable flaw sizes in ASME Section XI Paragraph IWB-3640 were revised to take into account the potential low fracture toughness , associated with flux shielded welds, the predicted end-of-fuel cycle (evaluation period) flaw size was ! compared to Table IWB-3641-5 (Reference 6) l allowable flaw depth values for a combination of dead weight, internal pressure, seismic, and differential thermal expansion / weld overlay shrink-age stresses. [ l CEC-73-203 3.2 Revision 0 g
I 3.2 Weld Overlay Repair Evaluation The following criteria were used by NUTECH to design / evaluate weld overlay repairs implemented or built-up during the Quad Cities Unit 2 Fall 1986 outage:
- 1. Circumferential flaw depth was assumed to equal 100% of the original pipe wall thickness by a conservative 360' length. If a circumferential flaw was drawn up into the overlay due to a steam blow-out, the actual flaw-depth was used.
I 2. Axial flaw depth was assumed to be a minimum of 100% of the original pipe wall thickness over its measured length. If an axial flaw was drawn up I into the overlay due to a steam blow-out, the actual flaw depth was used.
- 3. Credit was taken for the first layer if the delta ferrite content was at least 7.5 FN.
- 4. Under-the-overlay repair fatigue crack growth for circumferential and axial flaws was calculated for a 30 year design life based upon a conservative I fatigue crack growth correlation derived from data presented in EPRI Document NP-2423-LD (Reference 7).
- 5. For circumferential flaws, the weld overlay repair strength for a combination of dead weight, internal pressure, and seismic stresses was compared to the net section collapse criteria of ASME Section XI (References 5 or 6), Table IWB-3641-1. Table IWB-3641-1 arbitrarily has a cut-off point at a stress I ratio of 0.6; therefore, NUTECH has developed an CEC-73-203 3.3 Revision 0 nutech I
expanded version (Table 3.2-1) based upon the Table IWB-3641-1 source equations shown in Figure 3.2-1. I 6. For axial flaws, the weld overlay repair was compared to " leak barrier" weld overlay criteria presented in Table 3.2-2 from NUTECH Document COM-76-001 (Reference 8). I I I I I l I I I I CEC-73-203 3.4 Revision 0 nutech 1
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Table 3.2-1 mw 0 3y EXPANDED ALLOWABLE END-OF-EVALUATION PERIOD FLAW DEPTHIII-TO-THICKNESS RATIO FOR CIRCUMFERENTIAL FLAWS NORMAL OPERATING CONDITIONS P, # P b Ratio of Flaw Length, A g, to Pipe Circumference [ Note (3)]
" 0.5 (Note (2)) 0.0 0.1 0.2 0.3 0.4 or More 1.5 (4) (4) (4) (4) (4) (4)
" 1.4 0.75 0.40 0.21 0.15 (4 ) (4 )
m 1.3 0.75 0.75 0.39 0.27 0.22 0.19 1.2 0.75 0.75 0.56 0.40 0.32 0.27 1.1 0.75 0.75 0.73 0.51 0.42 0.34 1.0 0.75 0.75 0.75 0.63 0.51 0.41 0.9 0.75 0.75 0.75 0.73 0.59 0.47 0.0 0.75 0.75 0.75 0.75 0.68 0.53 0.7 0.75 0.75 0.75 0.75 0.75 0.58 0.6 0.75 0.75 0.75 0.75 0.75 0.63 0.5 (5) 0.75 0.75 0.75 0.75 0.75 0.68 0.4 (5) 0.75 0.75 0.75 0.75 0.75 0.73 0.36 (5) 0.75 0.75 0.75 0.75 0.75 0.75 NOTES: (1) Flaw depth = a n for a surface flaw 2a for a subsurface flaw t= nominal thi0kness i Linear interpolation is permissable. l (2) P,= primary membrane stress Pb " Primary bending stress l 3 S = allowable design stress intensity (in accordance with Section III) l C (3) Circumference based on nominal pipe diameter. (4) IWB-3514.3 shall be used, i d@ (5) Derived using source equations. l O 7
Table 3.2-2 LEAKAGE BARRIER REPAIR CRITERIA FOR AXIAL FLAWS (Reference 8) NONDIMENSIONAL FLAW LENGTH STRESS RATIO 4//NT l 0.00 0.25 0.50 1.00 2.00 ..... s 0.40 * * *
- z 0.50 * * * * =
0,m * . * . ; 0.70 * * *
- a
- lW8 3640 0.80 * * *
- r 0.90 * *
- a 0.96 *
- r 1.00 :
s I
- LEAK 8ARRIER ONLY REOUIRED I
STRESS RATIO = PD / 2 T Sm P = MAXIMUM PRESSURE FOR NORMAL OPERATING CONDITIONS D = NOMINAL OUTSIDE DIAMETER OF THE PIPE T = NOMINAL THICKNESS l y = END-OF. EVALUATION PERIOD Fl.AW LENGTH j R = NOMINAL RADIUS OF THE PIPE I l l I
- I i
CEC-73-203 3.7 ! Revision 0 nutech
I For a + 8 < 1800 I 8= 1e
-a*
2 (radians) 2.773 (SR)
-0.5-((2 sin 8-{sina) = 0 For I
a + 8 -> 1800
*(
I 8= 2-( h-{)(radians) 2.773 (SR) -0.5-h(2-{} sin 8 = 0
..r.,
a = half-crack length (radians) I 8 = neutral axis location angle (radians) a = flaw depth (inches) t = pipe thickness (inches) SR = stress ratio = Pm + Pb I Pm = primary membrane lIress Pb = primary bending stress Sm = allowable stress intensity (per ASME Section III Appendices) I I
-% k - -
\
\
N . - A e l I
\ NA - Neutral Axis I
a - Nean Radius Figure 3.2-1 SOURCE EQUATIONS FOR ALLOWABLE END-OF-EVALUATION PERIOD FLAW DEPTH-TO-THICKNESS RATIOS FOR CIRCUMFERENTIAL FLAWS I CEC-73-203 Revision 0 3.8 nutech I
I 4.0 APPLIED AND RESIDUAL STRESSES Various stress combinations are used in evaluating IGSCC flaws and repairs as explained in Section 3.0. The purpose of this section is to present the stresses acting on the weld locations discussed in this report. I 4.1 Primary Stresses Primary stresses include the effects of dead weight, internal pressure, and seismic loads. Internal pressure was obtained from previous NUTECH stress corrosion cracking evaluations (Reference 9). The dead weight and seismic stresses applied to each weld were obtained from Reference 10. These stresses are shown in Table 4.1-1. I 4.2 Secondary Stresses Secondary stresses include piping system differential thermal expansion stresses and through-pipe wall thermal gradient stresses caused by piping system thermal tran-sients; weld overlay shrinkage-induced stresses; and post-IHSI and under-the-overlay residual stresses. 4.2.1 I Thermal Stresses and Transients The piping system differential thermal expansion stresses for each weld were obtained from Reference 10 and are shown in Table 4.1-1. I Reference 1 defines the design transients for the recir-I culation system for Quad Cities Unit 2.
~
These tran-sients were conservatively grouped into three composite a transients. I The first composite transient is a startup/ shutdown transient with a heatup or cooldown rate of CEC-73-203 4.1 Revision 0 g I
1 L I L 100*F per hour. The second composite transient consists of a 50*F step temperature change with no change in pressure. The third composite transient is an emergency { event with a 416*F step temperature change and a pres-sure change of 75 psi. Figure 4.2-1 presents the number 7 of these cycles conservatively postulated during a 30-i year balance-of plant life design. These transients cause the through-wall temperature gradients detailed in I u Figure 4.2-2. [ 4.2.2 Weld Overlay Shrinkage-Induced Stresses { Each weld overlay causes a small amount of axial shrink-age underneath the overlay. This shrinkage induces bending stresses in the remainder of the piping system. g These shrinkage-induced stresses are calculated using 5 NUTECH computer program PISTAR (Reference 11). The l actual as-built shrinkages as shown in Table 4.2-1 are used in the analysis. The resulting shrinkage stresses are included in the IGSCC crack growth analysis of flaws in IHSI-mitigated welds and are shown in Table 4.2-2. 4.2.3 Residual Stresses Figures 4.2-3 and 4.2-4 present the through-wall post-IHSI residual stress distributions used in the IGSCC crack growth avaluation for IHCI-mitigated welds. These figures are taken from EPRI Document NP-2662-LD { (Reference 12). F Figure 4.2-5 presents the under-the-overlay through-wall residual stress distributions used in the fatigue crack growth evaluation for weld overlay repair design. This CEC-73-203 4.2 Revision 0 nutech I
e a figure is taken from Reference 13 and analyses performed L using the WELDS II computer program (Reference 14). m u I L I u F~ L r L E l I l l l l I L F I CEC-73-203 Revision 0 4.3 nutech
Table 4.1-1 QUAD CITIES UNIT 2 PRIMARY AND THERMAL EXPANSION AXIAL STRESSES
- I WELD NO.
PRESSURE STRESS (PSI) DW STRESS (PSI) THERMAL STRESS (PSI) OBE STRESS (PSI) I 02D-S3 02M-S4 02AS-S6 6811 6811 6892 738 875 410 2005 335 405 1976 1334 610 02AS-S12 6692 58 453 246 02AS-F14 6692 61 418 243 02AD-F12 6439 43 241 1029 02BS-F14 6692 90 1037 165 I 02BD-F8 02C-S3 02D-F6 6439 4239 28 543 1826 518 623 1305 4359 361 1468 2041 I 02E-F6A 02F-F6 02G-S3 4432 4239 4467 179 143 65 1282 2671 2246 2161 2166 1342 I 02J-F6 02K-S3 02K-S4 4163 4512 4457 180 44 39 340 576 261 2023 1335 842 02M-S3 4350 729 232 1206 02M-F7 3632 422 310 1597 lOS-F1 4139 1062 6149 1739 10S-F5 4009 336 6533 381 02A-S10 4732 0 0 1 02B-S9 4982 0 0 3 02AS-S4 4867 111 145 173 02AS-S9 4760 197 360 104 02BS-F2 4621 61 4780 297 02BS-S3 4749 51 3497 156 02BS-F7 4772 212 1663 237 02BD-S6 4632 13 1264 358 I I
- Based on as-built weld overlay repair thickness, where l applicable, plus original pipe wall thickness.
CEC-73-203 4.4 Revision 0 [Il{I()()hl I
[ Table 4.2-1 QUAD CITIES UNIT 2 { TOTAL AS-BUILT WELD OVERLAY SHRINKAGESII) Axial Shrinkage { WELD ID (in.) 02D-F6 0.108 02F-F6 0.257 { 02G-S3 0.280 02J-F6 0.263 02AS-S9 0.042 02BS-S3 0.063 b 02BS-F7 0.081 02BD-S6 0.065 [ 10S-F1 0.081 02E-F6A 0.287 02M-S3 { 02M-F7 0.253 0.199 02AS-S4 0.076(2) 10S-F5 0.070 02A-S10 N/A b 02B-S9 N/A 02C-S3 0.203 [ 02K-S3 02K-S4 0.168 0.234 02BSF2 0.044 { Notes: ( 1. Total of axial shrinkage recorded during Fall 1983, Spring 1985, and Pall 1986 outages.
- 2. 1986 shrinkage value not recorded. This value represents
{ the Spring 1985 shrinkage value with a factor of 2. b CEC-73-203 4.5 Revision 0 g
Table 4.2-2 QUAD CITIES UNIT 2 WELD OVERLAY REPAIR SHRINKAGE AXIAL STRESSES WOR STRESS WELD NO. (PSI) 02D-S3 1816 02M-S4 12659 02AS-S6 74 02AS-S12 127 02AS-F14 109 02AD-F12 66 02BS-F14 181 02BD-F8 69 02C-S3 5839 02D-F6 2340 02E-F6A 2350 02F-F6 2493 i 02G-S3 4334 02J-F6 3219 02K-S3 3586 02K-S4 3892 02M-S3 15027 02M-F7 2804 10S-F1 96 10S-F5 119 02A-S10 0 02B-S9 0 02AS-S4 70 I 02AS-S9 02BS-F2 95 0 02BS-S3 424 I 02BS-F7 02BD-S6 203 37 l r I i CEC-73-203 4.6 Revision 0 t1iatenc:l1 I
I ' I I h I NORMAL ~~ OPERATING b, d
=
I E w I k l 2. AM8lENT - 100 200 CYCLES CYCLES 1 CYCLE 30 YEAR BALANCE OF-PLANT DESIGN LIFE I TIME I Figure 4.2-1 OUAD CITIES UNIT 2 THERMAL TRANSIENTS l I CEC-73-203 4.7 Revision 0 nutech
- I '
u r " PIPE PIPE PIPE PIPE O D. 1.0, O.D. i D. L, o p AT i , , E a A T, i .o h 1 2(I FI NO ji il i FOR 304SS AT TNO = 5# F 7 E = 28.3 a 106 ,; E a = 9.11 x 10-6hp PIPE PIPE PIPE PIPE F O.0. __ I D. 0.0. _ _ 1.D. u p p AT 2 E c aT2
^ 0 "2
+
,NO 3 ,T, -T, j,
/ 1.-
n Thermal Transient Cycles L Pipe Start-up/ 50'F Step 416*F Step Diameter Parameter Shutdown Change Change 12" a Ty 2*F 32*F 265'F F aT 0*F 8'F 64*F 2 l 20" to 28" aT 1 6*F 36*F 302*F l AT 2 0'F 9'F 75*F Figure 4.2-2 QUAD CITIES UNIT 2 THROUGH-WALL TEMPERATURE GRADIENTS CEC-73-203 4.8 Revision 0 nutech
.. ---- ------- -- - - - - - - - - - - - - - - - - --- a
L L l r [ L M Ps M Pe
-300 -200 -soo o soo 200 soo -300 200 -soo o soo 200 soo os- ,
OUTER SimFACE os. ,, [ WELDNeG
\ 2, /
-- *Ej;gNs $-
h o I(IS.2cm)'Y!as- / [
/
/
. ._ I l
'u m~
W I l L 0 *" ' *~ ~'8 s.o/ -OSSI (1.Sica) OY2in 10.50cm) _ p/
- a s.575 a 5
(13.6 Scal , 5 03- f g3 l l E f 02- -os 02-- 0.S I ea N [ d on-5 N o.t-a
$ INNER StmFACE
-40 20 o to o -40 -20 o to o RES10ual AMi&L STRESS,kai REstouAL CIRCUMFERENTIAL STRESS,bei Figure 4.2-3 PRE- AND POST-IHSI THROUGH-WALL RESIDUAL STRESS DISTRIBUTIONS FOR 12" NPS PIPES (Reference 12)
[ , CEC-73-203 49 Revision 0 [ nutech
~
l
L L L E 1 L u p. u p.
-300 200 -80 0 0 00 0 300 300 -300 -200 -60 0 0 00 0 300 300 400 WELD .1 3 T' (33 Sem) ,3
/
WELD + lig g hl40nd e.g . 8
--I W g_o.
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-l 3in(3.3 cal i
~ 3 3 ""'
ra -t 5 y
/ S s
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/
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/
/
/
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>- en.
s 40
-40
-20 0
\. to 40
-40 40
-20 0 20 40 MS40uhL AMIAL STMSS, tel MS1004L CNICUIWERENflAL STMSS, nel
[ Figure 4.2-4 PRE- AND POST-IHSI THROUGH-WALL RESIDUAL STRESS DISTRIBUTIONS FOR 28" NPS PIPES (Reference 12) [ CEC-73-203 4.10 Revision 0 nutech h i
u J H F L E u m . . . . . . . , , .
- OUTER SURFACE y at
- - 80 -
- 80
=
- 80 h E
- - 40 . 40 E
l 5 E
-- 20 -
- 20 l;i
- INNER SURFACE 5 R R t i G t e e e t l 80 40 20 0 20 -40 -80 40 20 0 20 40 RESIDUAL AXIAL STRESS, kel RESIDUAL CIRCUMFERENTIAL STRESS, kal l
Figure 4.2-5 UNDER-THE-O_VERLAY THROUGH-WALL RESIDUAL STRESS DISTRIBUTIONS l CEC-73-203 4.11 Revision 0 nutech
m y 5.0 EVALUATION METHODS AND RESULTS This section presents the evaluation methods and results used to assess the acceptability of the overlay-repaired and IHSI-mitigated weld flaws at Quad Cities Unit 2. 5.1 IHSI-Mitigated Welds 5.1.1 Flawed Pipe Analysis Table 5.1-1 presents the pipe and flaw geometric details needed to calculate applied stresses and predict crack [ growth in the IHSI-mitigated flawed welds at Quad Cities Unit 2. NUTECH's NUTCRAK computer program (Reference 15) l was used to predict crack growth. The following i conservative crack growth law was used: h=3.58x 10 K f where: I l da = differential crack size (inches) dt = differential time (hours) l K = applied stress intensity factor (ksim/in.) I As discussed in Section 3.1, this crack growth correlation closely agrees with the NRR curve presented in Figure 3.1-1 from NUREG-1061, Volume 1 (Reference 3). Table 5.1-2 l presents the predicted end-of-cycle flaw depths for the IHSI-mitigated flawed welds. These evaluations indicate that no further IGSCC crack growth ia expected for the balance-of-plant life. CEC-73-203 5.1 Revision 0 g I
5.1.2 Flawed Pipe Evaluation As discussed in Section 3.1, the predicted end-of-fuel cycle flaw depth for IHSI-mitigated welds were compared to two different evaluation criteria. Table 5.1-3 presents flaw geometric details and primary stress combinations I needed to evaluate the requirements of USNRC Generic Letter 84-11 (Reference 4) and ASME Section XI (Reference 5), Table IWB-3641-1. Table 5.1-4 presents flaw geometric details and primary plus secondary stress ratios needed to evaluate the requirements of ASME Section XI (Reference 6) Table IWB-3641-5. Table 5.1-5 presents allowable flaw lengths for assumed 100% through-wall flaws using the limit moment approach shown in Section 3.1. This conservative evaluation technique complies with the requirements of USNRC Generic Letter 84-11. 5.2 Overlay-Repaired Welds I Table 5.2-1 presents the pipe and flaw geometric details needed to calculate the applied and allowable stress ratios for the circumferential1y flawed overlay-repaired welds at , Quad Cities Unit 2. Applied stresses are found in Table l 4.1-1. Table 5.2-2 presents a comparison of stress ratios due to applied loads versus the allowable stress ratios for the circumferential flaws detailed in Table 5.2-1. As discussed in Section 3.2, the allowable stress ratios shown were calculated using the source equations of ASME Section XI Table IWB-3641-1. I Table 5.2-3 presents the pipe and flaw geometric details needed to determine applied and allowable stress ratios for l the overlay-repaired welds at Quad Cities Unit 2 with axial l CEC-73-203 5.2 Revision 0 nutech l I
u I~ wall surface are bounded by the full-structural weld overlay repair evaluation presented in Tables 5.2-1 and 5.2-2). Table 5.2-4 presents a comparison of stress I ratios due to applied loads versus the allowable stress ratios for the axial flaws given in Table 5.2-3. The allowable stress ratios shown were determined using the leakage barrier criteria presented in Table 3.2-1. L E I l I l I l I 1 I l I l I I CEC-73-203 5.3 Revision 0 nutech i I
r L Table 5.1-1 I PIPE AND FLAW GEOMETRIC DETAILS CIRCUMFERENTIALLY FLAWED IHSI-MITIGATED WELDS I l Nominal Sustained g O.D.II) t II a I) Stress (5) L Weld ID (in.) (in.) (%) L I4) (psi) ( 02D-S3 12.75 0.585 17 360' 11,369 02M-S4 12.75 0.585 12 360' 20,679 f 02AS-S6 28.0 1.203 18 360' 7,580 0 2 AS--S 12 28.0 1.203 22 360* 7,331 02AS-F14 28.0 1.203 14 360' 7,279 02AD-F12 28.0 1.359 17 360' 6,788 02BD-F8 28.0 1.359 15 360' 8,361 [ f Notes:
- 1. O.D. = outside diameter
- 2. t = pipe wall thickness
- 3. a = beginning-of-cycle flaw depth
- 4. L = evaluation flaw length
( 5. Sustained stress = dead weight + internal pressure + thermal expansion + weld overlay shrinkage stresses from Tables 4.1-1 and 4.2-2. { [ CEC-73-203 5.4 { Revision 0 nutech
I Table 5.1-2 CIRCUMFERENTIALLY FLAWED IHSI-MITIGATED WELDS PREDICTED END-OF-CYCLE FLAW DEPTHS I I Weld ID Beginning-of-Cyc Flaw Depth Ratio ) Predicted End-of-Cycle Depth RatioI yaw 02D-S3 I 0.17 0.17 02M-S4 0.12 0.12 02AS-S6 0.18 0.18 02AS-S12 0.22 0.22 02AS-F14 0.14 0.14 02AD-F12 0.17 0.17 02BD-F8 0.15 0.15 I I I Notes:
- 1. Flaws assumed to be 360' in circumferential length.
- 2. Predicted end-of-cycle flaw depth based upon combination of dead weight, internal pressure, thermal expansion, overlay i shrinkage, and post-IHSI through-wall residual stresses.
l I I iI l CEC-7 3-203 Revision 0 5s nutech 1
mM M m m m m m m me e mmag g a g
- a n
*M Table 5.1-3
?.?
$. d CIRCUMFERENTI ALLY FLAWED IHSI-MITIGATED WELDS oa 3 GENERIC LETTER 84-11/ TABLE IWB-3641-1
" PR ED ICT ED VS. ALLOWABLE FLAW DEPTH RATIOS l
IWB-3641-1 GL 84-11 Predicted Weld L III ID (in.) FLR(2) SR(3) FDR I4) FDR(5) FDR I0I j 0.015 0.56 0.75 0.50 0.17 l 02D-S3 0.6 0.012 0.53 0.75 0.50 0.12 02M-S4 0.5 0.091 0.45 0.75 0.50 0.18 02AS-S6 8.0 0.148 0.41 0.75 0.50 0.22 02AS-S12 13.0 0.489 0.41 0.73 0.49 0.14 02AS-F14 43.0 0.011 0.44 0.75 0.50 0.17
, 02AD-F12 1.0 0.75 0.50 0.15 h 02BD-F8 4.5 0.051 0.42 Notes:
- 1. Flaw le ng th, L, is maximum combination of circumferential flaw lengths on cither side of weld from Table 1. 0-4.
- 2. FLR = flaw length ratio = flaw le ng t h, L, divided by nominal pipe circumference.
- 3. SR = dead weight plus internal pressure plus seismic stresses (Table 4.1-1) divided by allowable stress intens ity, Sm. From ASME Section III (Reference 16) Appendix I, Table I-1.2, S, = 16,950 psi for 304 stainless steel pipe and fittings at 550*F ope rating temperature.
C 4. FDR = flaw depth ratio (^) from ASME Section XI (Reference 5) Table IWB-3641-1.
- 5. Allowable flaw depth ratio ( x ) per USNRC Generic Letter 84-11 (Reference 4).
O 6. Predicted end-of-fuel cycle flaw depth ratio from Table 5.1-2. I
Table 5.1-4 l CIRCUMFERENTIALLY FLAWED IHSI-MITIGATED WELDS TABLE IWB-3641-5 PREDICTED VS. ALLOWABLE FLAW DEPTH RATIOS Weld L(1) IWB-3641-5 Predicted ID (in.) FLR(2) SR(3) FDR I4) FDR(6) 02D-S3 0.6 0.015 0.72 0.60 0.17 02M-S4 0.5 0.012 0.90 0.58 0.12 02AS-S6 8.0 0.091 0.52 0.60 0.18 02AS-S12 13.0 0.148 0.47 0.60 0.22 02AS-F14 43.0 0.489 0.47 0.49 0.14 02AD-F12 1.0 0.011 0.50 0.60 0.17 02BD-F8 4.5 0.051 0.51 0.60 0.15 I I I Notes:
- 1. Flaw length, L, is maximum combination of circumferential flaw lengths on either side of weld from Table 1.0-4.
I 2. 3. FLR = flaw length ratio = flaw length, L, divided by nominal pipe circumference. SR = M [(dead weight plus internal pressure plus seismic I stresses) + (thermal expansion plus weld overlay shrinkage stresses divided by 2.77)] divided by allowable stress intensity, S , defined in Note 3, Table 5.1-3. Used worst M
= 1.116 for SAW weldment with 28 inch outside diameter.
I 4. FDR = flaw depth ratio (") from ASME Section XI, Table IWB-3641-5 (Reference 6).
- 5. Predicted end-of-fuel cycle flaw depth ratio from Table 5.1-2.
I I CEC-73-203 5.7 Revision 0 b i
Table 5.1-5 CIRCUMFERENTIALLY FLAWED IHSI-MITIGATED WELDS GENERIC LETTER 84-11 LIMIT MOMENT ALLOWABLE vs. ACTUAL FLAW LENGTH Weld Allowable Circ. Actual Circ. ID Flaw Length (in.)III Flaw Length (in.)(2) I 02D-S3 18 0.6 02M-S4 18 0.5 02AS-S6 41 8 I 02AS-S12 02AS-F14 42 43 13 43 02AD-F12 41 1 02BD-F8 41 4.5 I Notes: I 1. Calculated using limit moment formulation presented in Section 3.1.
- 2. From Table 1.0-4.
I I I I I CEC-73-203 5.8 Revision 0 nutech I
m mm m m M M M M M M M M M M M M Table 5.2-1
$$ PIPE AND FLAW GEOMETRIC DETAILS
{h OVERLAY-REPAIRED WELDS OE Nominal l o8 Weld O.D.II) tp I } to I } t I4) a( } ID (in.) (in.) (in.) (in.) (in.) L(6) 02C-S3 12.75 0.585 0.355 0.940 0.590 360* 02D-F6 12.75 0.585 0.3 29 0.914 0.590 360* 02E-F6A 12.75 0.585 0.314 0.899 0.590 360* 02F-F6 12.75 0.585 0.355 0.940 0.590 360* 02G-S3 12.75 0.585 0.307 0.892 0.590 360* 02J-F6 12.75 D.585 0.372 0.957 0.590 360* 02K-S3 12.75 0.585 0.298 0.883 0.590 360* 02K-S4 12.75 0.585 0.309 0.894 0.590 360* 02M-S3 12.75 0.585 0.331 0.916 0.590 360* 02M-F7 12.75 0.585 0.512 1.097 0.590 360* w 10S-F1 20.00 1.016 0.494 1.510 1.021 360* 10S-F5 20.00 1.016 0.543 1.559 1.021 360* 1.078 I7) 02A-S10 22.00 0.979 0.474 1.453 360* 028-S9 22.00 0.979 0.401 1.380 0.9 84 360* 02AS-S4 28.00 1.203 0.451 1.654 1.208 360* 02AS-S9 28.00 1.203 0.488 1.691 1.208 360* 02BS-F2 28.00 1.203 0.508 1.711 1.208 360* 02BS-S3 28.00 1.203 0.492 1.695 1.208 360* 02BS-F7 28.00 1.203 0.484 1.687 1.208 360* 02BD-S6 28.00 1.359 0.530 1.889 1.364 360* Notes:
- 1. O.D. = outside diameter.
- 2. t g = original pipe wall thickness.
- 3. tg = weld overlay repair thickness from Table 2.0-1.
- 4. t =t +t
- 5. a = eOaluaEion flaw depth = t p + fatigue crack growth of 0.005".
7 6. L = evaluation flaw le ngt h. C 7. a = evaluation flaw depth = t +t - remaining ligament + bounding f atigue crack gEowth of 0.005". O 7
Table 5.2-2 APPLIED VS. ALLOWABLE STRESS RATIOS { OVERLAY-REPAIRED WELDS E Weld IWB-3641-1 Predicted ID FLR III SR(2) FDR I3) FDR I4) 02C-S3 1.0 0.36 0.75 0.63 02D-F6 1.0 0.40 0.73 0.65 02E-F6A 1.0 0.40 0.73 0.66 - {- 02F-F6 1.0 0.39 0.73 0.63 02G-S3 1.0 0.35 0.75 0.66 r 02J-F6 1.0 0.38 0.74 0.62 L 02K-S3 1.0 0.35 0.75 0.67 02K-S4 1.0 0.31 0.75 0.66
-02M-S3 1.0 0.37 0.74 0.64
{ 02M-F7 10S-F1 1.0 1.0 0.33 0.41 0.75 0.72 0.54 0.68 10S-F5 1.0 0.28 0.75 0.65 r 02A-S10 1.0 0.28 0.75 0.74 L 02B-S9 1.0 0.29 0.75 0.71 02AS-S4 1.0 0.30 0.75 0.73 02AS-S9 1.0 0.30 0.75 0.71 [ 02BS-F2 1.0 0.29 0.75 0.71 02BS-S3 1.0 0.29 0.75 0.71 02BS-F7 1.0 0.31 0.75 0.72 { 02BD-S6 1.0 0.30 0.75 0.72 [l Notes:
- 1. FLR = flaw length ratio = 1.0 for 360* assumed flaw length.
[ 2. SR = dead weight plus internal pressure plus seismic stresses (Table 4.1-1) divided by allowable stress intensity, S,, defined in Note 3, Table 5.1-3. ( 3. FDR = allowable flaw depth ratio (*) from ASME Section XI (References 4 or 5), Table IWB-364I-1.
- 4. Predicted FDR = bounding end-of-evaluation period
[- circumferential flaw depth, a, from Table 5.2-1 divided by "t" from Table 5.2-1. E CEC-73-203 5.10 { Revision 0 [j(j{gg(;()
L F L Table 5.2-3 L OVERLAY-REPAIRED WELDS I PIPE AND FLAW GEOMETRIC DETAILS AXIALLY FLAWED WELDS L f Nominal L (3) Weld O.DIII L(2) t P t r(4) y ID (in.) (in.) (in.) (in.) L 02C-S3 12.75 0.75 0.585 0.34 [ 02A-S10 22.0 1.0 0.979 0.35 r L [ Notes:
- 1. O.D. = outside diameter.
- 2. Flaw length, L, is maximum single axial flaw length
[ on either side of weld from Table 1.0-3. g = original pipe wall thickness.
- 3. t L 4. tr = remaining ligament thickness from Table 1.0-3.
[ [ [ E CEC-73-203 5.11 { Revision 0 nutech
Table 5.2-4 OVERLAY-REPAIRED WELDS APPLIED VS. ALLOWABLE STRESS RATIOS AXIALLY FLAWED WELDS I Applied Allowable Standard Predicted weld Stress Stress t o(3) tr ID RatioIII Ratio (2) (in.) (in.) 02C-S3 0.80 0.90 0.125 0.325 02A-S10 0.83 0.90 0.125 0.335 I Notes:
- 1. Applied stress ratio is calculated for internal pressure of 1,250 psi using geometric properties from Table 5.2-3 and formula presented in Table 3.2-2 footnotes.
- 2. Allowable stress ratio per Table 3.2-2.
- 3. Standard leak barrier overlay repair minimum thickness.
- 4. Predicted t r = current remaining ligament - bounding fatigue crack growth of 0.015".
1 i , II ! CEC-73-203 5.12 Revision 0 tilitEBC;Il
6.0
SUMMARY
AND CONCLUSIONS Examinations performed during the Fall 1983 and Spring 1985 outages of the Reactor Recirculation and Shut Down Cooling systems at Commonwealth Edison's Quad Cities Nuclear Power Plant Unit 2 identified flaws judged to be I IGSCC in the vicinity of twenty-four welds. Fourteen welds were overlay repaired, nine welds were shown to be acceptable with only IHSI mitigation, and one weld was removed and replaced. During the examinations performed in the Fall 1986 outage, five new flaws were identified. Four of these welds were overlay-repaired; the other was shown to be acceptable with only IHSI mitigation. Two of the nine welds found to I be acceptable during the 1983 and 1985 outages with only IHSI mitigation were repaired with overlays during the 1986 outage. One other of these nine welds was found to I have inside diameter root geometry indications and was, therefore, classified as uncracked during the 1986 outage. The fourteen overlays applied during the 1983 and 1985 outages were upgraded to full-structural overlays and the six new overlays were designed as full-structurals. Hence, at the end of the Fall 1986 outage, a total of I twenty full-structural weld overlay repairs have been applied to various welds at Quad Cities Unit 2. Seven welds with flaws were found to be acceptable with IHSI mitigation only. The evaluation of the twenty-seven overlay-repaired and IHSI-mitigated weld flaws presented in this report demon-strates that the applied stress levels are acceptable for all design conditions. The analysis performed in the evaluation demonstrates that the overlay-repaired weld flaws are acceptable for the balance-of plant life and CEC-73-203 6.1 Revision 0 nutech
IHSI-mitigated weld flaws are acceptable for a minimum of one additional fuel cycle. As noted in Section 1.0, all of the ultrasonic examination (UT) results reported for the weld overlay repairs implemented or built-up during the 1986 outage were observed using EPRI qualified manual UT techniques except for Weld 02A-S10. For this weld, EPRI qualified automated UT techniques were employed due to high noise levels in I the overlay. Use of the automated techniques resulted in remaining ligament values larger than those determined using the manual techniques. Because the smaller manual technique remaining ligament values do not completely comply with the requirements of ASME Section XI (References 5 or 6), Paragraph IWB-3641, elastic plastic I fracture mechanics analyses were performed to confirm compliance of these smaller ligament thicknesses with the requirements of Paragraph IWB-3642. These analyses are I documented in a separate report and demonstrate complete compliance with Paragraph IWB-3642. The weld overlay repair design calculations for Weld 02A-S10 presented in Appendix A demonstrate that a full-structural overlay thickness exists over the axial flaws in this weld. This approach is very conservative due to 1 i the differences in applied loads, fracture mechanics behavior, and IGSCC-character of axial versus circum-ferential flaws. I CEC-73-203 6.2 Revision 0 nutech
7.0 REFERENCES
- 1. NUTECH Document No. COM-75-002, " Evaluation and Disposition of IGSCC Flaws at Quad Cities Nuclear Power Station Unit 2", Revision 1, March 1984.
- 2. NUTECH Document No. CEC-20-013, " Evaluation and Disposition of Flaws at Quad Cities Nuclear Power ,
Plant Unit 2", Revision 1, July 1985.
- 3. U.S. Nuclear Regulatory Commission Document No.
NUREG-1061, " Investigation and Evaluation of Stress-Corrosion Cracking in Piping of Boiling Water Reactor Plants", March 1984, Draft attached to SECY-84-301, dated July 30, 1984.
- 4. USNRC Generic Letter 84-11, Inspections of BWR Stainless Steel Piping", April 19, 1984.
- 5. ASME Boiler and Pressure Vessel Code Section XI, 1983 Edition with Addenda through Winter 1983.
- 6. ASME Boiler and Pressure Vessel Code Section XI, 1983 Edition with Addenda through Winter 1985.
I 7. EPRI Document No. NP-2423-LD, " Stress Corrosion Cracking of Type-304 Stainless Steel in High-Purity Water: A Compilation of Crack Growth Rates", June 1982.
- 8. NUTECH Document No. COM-76-001, " Weld overlay Design Criteria for Axial Cracks", Revision 0, March 1984.
1 CEC-73-203 7.1 l Revision 0 nutech
I
- 9. NUTECH Document No. COM-57-003, " Stress Corrosion Cracking Evaluation Program for Quad Cities Station Unit 2", Revision 0, March 1983.
- 10. EDS Reactor Recirculation System Analysis (NRC IE Bulletin 79-14), NUTECH File CEC 073.0010.0029.
I 11. NUTECH Computer Program PISTAR, Version 3.3.1, User's Manual, Volume 1, TR-76-002, Revision 10, NUTECH File OASJO. SOFT.2.036.00.
- 12. EPRI Document No. NP-2662-LD, " Computational Residual Stress Analysis for Induction Heating of Welded BWR Pipes", December 1982.
I 13. EPRI Document, " Continued Service Justification for Weld Overlay Pipe Repairs," Final Draft, May 25, 1984.
- 14. NUTECH Computer Program WELDS II, Version 1.0.0, July 1983, NUTECH File OASJO. SOFT.2.052.00.
- 15. NUTECH Computer Program NUTCRAK, Revision 2.0.2, December 1983, NOTECH File OASJO. SOFT.2.049.00.
I 16. ASME Boiler and Pressure Vessel Code Section III, 1983 Edition with Addenda through Winter 1985. I I I CEC-73-203 Revision 0 7.2 nutech I
1 L F L, F L b Appendix A FULL-STRUCTURAL WELD OVERLAY ( REPAIR CALCULATION FOR WELD 02A-S10 L E E E E [ [ [ [ CEC-73-203 A.0 Revision 0 nutech m.-.
I I Pipe Geometry: t p = 0.979" (from Table 5.2-1) Actual Weld overlay Repair Geometry: t o = 0.474" (from Figure 2.0-1) Applied Stresses (from Table 4.1-1 for t p +to): Internal Pressure = 4,732 psi I Dead Weight / Seismic = Negligible Balance-of-Plant Life Fatigue Crack Growth sfrom Table 5.2-1) = 0.005" Minimum Weld Overlay Repair Thickness Design: I Try tmin. = 0.33" Applied Stress = 4,732 psi 4 3 I
= 5,253 psi S,= 16,950 psi (from Table 5.1-3)
SR = Applied Stress /S,
= 0.31 Allowable Flaw Depth Ratio (f) for l SR = 0.31 and Flaw Length = 360*:
{=0.75(fromTable3.2-1) Actual Flaw Depth Ratio ( ) for Plaw Depth = 100% Pipe Wall Thk.: I a' t
" O.979" + 0.005" 0.979" + 0.33" = 0.75 Therefore, 0.33" weld overlay repair thickness is acceptable.
I l CEC-73-203 A.1 Revision 0 gg l l t
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