ML20215G458

Rev 1 to Flaw Evaluation & Repair Design for Plant Ei Hatch Unit 1 Spring 1987 Outage

ML20215G458
Person / Time
Site:	Hatch
Issue date:	06/11/1987
From:	Copeland J, Giannuzzi A, Gustin H STRUCTURAL INTEGRITY ASSOCIATES, INC.
To:
Shared Package
ML20215G438	List: ML20215G435 ML20215G458
References
SIR-87-014, SIR-87-014-R01, SIR-87-14, SIR-87-14-R1, TAC-64777, NUDOCS 8706230265
Download: ML20215G458 (45)

Text

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( SI Report No: SIR-87-014-Revision.1 Project No. SCS-02 f June 11, 1987 Flaw Evaluation and Repair Design for Plant E.I. Hatch Unit 1 Spring 1987 Outage Prepared by Structural Integrity Associates Prepared by: -

Date: b ~ll ~ b '

H. L. Gustin P.E.

l Prepared by:

Date: bY7f[

l J. F. Cdpeland P

-Reviewed and Approved by:' / N Date: / {' 1 A. Giannuzzi //

i 8706230265 870612 ADOCK 050 1 gDR l

3

Flaw Evaluation and Repair Design SIR-87-014 for Plant E. I. Hatch Unit 1 ,

Spring 1987 Outage REVISION CONTROL SHEET I

PAGES PARAGRAPH (S) DATE REVISION REMARKS j

{ Initial Issue 1-27 All 6-1-87 0 A.1-A.2 All 6-1-87 0 B.1-B.5 All 6-1-87 0 6-11-87 1 Added Certification l l

4 All 6-11-87 1 Incorporated Client Comments

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Flaw Evaluation and Repair Design for Plant E.I. Hatch Unit 1 Spring 1987 Outage Revision 1, June 11, 1987 .

CERTIFICATION I, Harry L.- Gustin, a Registered Professional Engineer under the ,

laws of the State of Illinois, certify that this report and the data' contained herein are correct and complete to the best of my l knowledge and belief, and that the analyses described herein meet the requirements of.ASME Boiler and Pressure Vessel Code,Section XI, 1986 Edition. I -further certify that this report was prepared by me or under my direction, or reviewed by me, and that I am competent to review this document.

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""1,' g ' Harry L. Gustin, P. E.

.*****... Registered Professional Engineer

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State of Illinois 062-039110 (N; PRCFE93'CNAL

/ 62 3G110 REG 15T EROS Date: M iI }9  ;

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TABLE OF CONTENTS Pacre r I

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1.0 INTRODUCTION

. . . . . . . . . . . . . 1 1 2.0' LIMITED SERVICE WELD' OVERLAY DESIGN . . . . . 3 j 3.0 EVALUATION OF FLAWS IDENTIFIED IN RECIRCULATION SYSTEM WELDS . . . . . .. . . . . . . . 14 4.0 SAFETY EVALUATION . . . . . . . . . . . 23

5.0 CONCLUSION

S . . . . . . . . . . . . . 25 i

6.0 REFERENCES

. . . . . . . . . . . . . 27 '

APPENDIX A - Section XI, IWB-3500 Evaluation of Subsurface Indications in Weld overlays (Welds 1B31-1RC-28B-4 and 1E11-1RHR-24B-R-12) l APPENDIX B -. Allowable Flaw Size and Crack Growth calculations (Weld 1B31-1RC-28B-10)

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LIST OF TABLES Table P_a,ge_

2-1 Flaw Indications Identified in Reactor Water Clean-up Welds - 1987 . . . . . . . . . 5 2-2 Reactor Water Clean-up Weld Stresses (psi) . . 6 2-3 Allowable Flaw Size for Axial Crack, Wrought /

Cast Stainless Steel (Welds RWCU 6-D-6 and 6-D-14) . . . . . . . . . . . . . 7 2-4 Allowable Flaw Size for Circumferential Crack, Flux Weld (Weld RWCU 6-D-6 with small welds) . . 8 2-5 Allowable Flaw Size for Circumferential Crack, Flux Weld (Weld RWCU 6-D-14) . . . . . . . 9 2-6 Allowable Flaw Size for Circumferential Crack, Flux Weld (Weld RWCU 6-D-17) . . . . . . . 10 3-1 Flaw Indications in Weld Overlay Material (1987) . . . . . . . . . . . . . 17 3-2 Flaw Indications in Weld Overlay Material (1986) . . . . . . . . . . . . . . 18 3-3 Flaw Indications in Welds 1B31-1RC-28A-2, -28B-8 and -28B-10 (1987) . . . . . . . . . . 19 3-4 Flaw Indications in Welds 1B31-1RC-28A-2, -28B-8 and -28B-10 (1985/1986) . . . . . . . . . 20 B-1 Allowable Flaw Size for Circumferential Crack, Flux Weld . . . . . . . . . . . B-1 B-2 Allowable Flaw Size for Circumferential Crack, Flux Weld . . . . . . . . . . . . . B-2 B-3 Stress Corrosion Crack Growth Analysis . . . . B-3

LIST OF' FIGURES-

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'Ficure Page 2-l' Limited Service Overlay Design for Weld Number G31-RWCU-6-D-17 . . . . . . . . . 11' 2-2' Limited Service Overlay Design for Weld Number G31-RWCU-6-D-6 . . . . . . . . .. 12:

2-3 . Limited Service _ Overlay Design for Weld Number.G31-RWCU-6-D-14 . . . . . .. . . . 13 3-1 As-Welded Residual Stress Distribution l Used For Crack Growth Analysis of Weld 1B31-1RC-28B-10 . . . . . . . . . . . 21  ;

3-2 IGSCC Growth for Weld 1B31-1RC-28B-10 in the As-Welded Condition . . . . . . .. . . . 22 i

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1.0 INTRODUCTION

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L As a result of' inservice inspections performed during the Spring, 1987 refueling outage at Georgia Power Company's Plant E.I. Hatch 1 Unit 1, flaw indications believed to be due to intergranular j j stress corrosion. cracking (IGSCC) were identified at three-weld locations in the reactor water clean-up (RWCU) system. .In f

t. addition, the. flaw characterizations were revised on three welds  !

in the 28" section of . the recirculation system which were not previously repaired by weld overlay. Embedded flaws in two weld overlay repairs (one in 28" recirculation, and one in 24" residual heat removal (RHR)) were also characterized slightly l differently than previously.

i Limited service weld. overlay repairs were designed for the three welds with flaw indications in the RWCU system. These repairs are . intended for use only until the next refueling outage in accordance with NUREG-0313, Revision 2 (Draft) [1]. At that time the repaired locations will be replaced, or the repairs will be  !

upgraded for extended service.

The flaws at the five welds in the recirculation and RHR systems were also evaluated under the criteria of NUREG-0313 Revision 2 (Draft) [1] and shown to be acceptable for service for another I'

operating cycle with no further action. Each of these locations either has an existing weld overlay in place which meets the requirements of the NUREG-0313 " Standard Weld Overlay", or has been treated with the induction heating stress improvement (IHSI) process.

l Section 2 of this report discusses the design of the limited I

service weld overlays on the RWCU at Hatch. Section 3 presents the results of the flaw evaluation analyses which were performed l l

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for the newly defined flaws in the five locations in the recirculation and RHR systems. Section 4 presents a Safety  ;

Evaluation for these repairs and flaw evaluations in 10CFR50.59 l format. Section 5 summarizes the results and conclusions of this I report.

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2. 0. LIMITED SERVICE WELD OVERLAY DESIGN i

i The flaw. indications identified in the three welds in the RWCU system are summarized in Table 2-1. These flaws are relatively minor,.and present 'no threat to the structural integrity of the ] i concerned ~ welds at the present time. These welds had previously

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received IHSI treatment, which should serve to arrest the growth l of the indicated flaws, particularly in the length direction. UT inspection techniques had also been modified since the last inspection to provide more . sensitive detection of- these i indications.

The stresses at these welds are presented in Table 2-2, with the stress components calculated from information in the design stress report [2].

NUREG-0313, Revision 2 (Draft) [1] defines three categories of weld overlay repairs. Because Georgia Power intends to upgrade or replace these repairs during the next refueling outage, and in order to minimize the personnel radiation exposure due to I

performing repairs on these locations (since the repairs were performed manually), the repairs to these three locations were designed as limited service weld overlay repairs.

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l The Limited Service Overlay designs (per NUREG-0313, Rev. 2, Draft) are included as Figures 2-1, 2-2, and 2-3 [6]. pc-CRACK j [7] runs for determining allowable flaw sizes are also included l

l (Tables 2-3 through 2-6), for circumferential and axial cracks, I and show that the reported indications are acceptable without repair, if their size does not change. These pc-CRACK runs meet the criteria of Section XI IWB-3641 tables (Winter 85 Addenda) 1

[4] for shielded metal arc (SMAW) welds. Stresses are based on 3

l the GE stress report [2] for the RWCU line. The maximum reported circumferential indication size for the RWCU is 55% of wall by i 0.7" long in this 6.628" OD pipe, and the maximum axial l j indication is 66% of wall by 0.1" long.  ;

Thus, no structural reinforcement is required, and Limited Service overlays are justified to provide further compressive residual stresses at the indications and to provide leak barriers. The 2-layer thickness (after PT-clear surface) is considered adequate for this purpose. The required full thickness width of the overlays for the pipe-elbow welds (6-D-6 and 6-D-17) is 2", which is greater than 1. 54 RT = v 1.54(3.314)(.45) = 1.83" (the criterion for previous overlays, exclusive of UT requirements which are not a factor for limited >

service). The full thickness width of the overlay for the elbow-cast valve weld (6-D-14) is 1", centered over the defect indication in the elbow, so as not to weld on the cast valve.

These designs are adequate for limited service, per NUREG-0313, Rev. 2 (Draft).

Weld overlay shrinkage-induced stresses are not expected to present a significant concern on the reactor water clean up ,

system. This is due to the fact that there are no weld locations in the reactor water clean up system which contain identified unrepaired flaws potentially affected by shrinkage stresses. In addition, the new overlays are short and relatively thin, so the magnitude of shrinkage streses is anticipated to be minimal (on i the order of a few ksi or less).

During the next refueling outage, the limited service overlay 4 repairs will be re-evaluated. Longer term analysis of weld overlay-induced shrinkage stresses for the RWCU system will be l

based upon the final disposition of the repairs.

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TABLE 2-1 FLAW INDICATIONS IDENTIFIED IN REACTOR WATER CLEAN-UP WELDS 1987 l- WELD. FLAW' CHARACTERIZATION j 6-D-6 1. Circ. 0.35" long with i associated' axial component 33% TWC

.2. Axial 0.1" long x 33% TWC l

6-D-14 1. Circ. 0.7" long x 55% TWC i

2. Axial 66% TWC associated with #1-6-D-17 1. Circ. 0.6" long x 55% TWC l

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TABLE 2-2 REACTOR WATER CLEAN-UP WELD: STRESSES ('si) p WELD' NODE PRESSURE DEADWEIGHT ' SEISMIC THERMAL.

6-D-6' 830 4603' 184 3890 3849 6-D-14 .867~ 4603 678_ 1410- 5254-6-D-17 880' 4603 963 1217 2456 NOTE:

The above stresses were taken from Reference-(2), with results

[ scaled to reflect measured wall thicknesses of 0.45".

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i tm pc-CRACK (C) COPYRIGHT-1984, 1986 STRUCTURAL INTEGRITY ASSOCIATES, INC.

SAN JOSE, CA (408)978-8200 VERSION 1.1 TABLE 2-3 ALLOWABLE FLAW SIZE EVALUATION 6LLOWABLE FLAW SIZE FOR AXIAL CRACK, WROUGHT / CAST STAINLESS f

• PC g WELDS RWCU 6-D-6 AND 6-D-14 g

ALL THICKNESS = 0.4500 EMBRANE STRESS = 7364.0000 TRESS RATIO = 0.4345 LLOWABLE STRESS =16950.0000 hLOW STRESS =50850.0000 L/SQRT(RT) )

0.00 0.50 1.00 2.00 3.00 4.00 5.00 6.00 l tLLOWABLE A/T 0.7500 0.7500 0.7500 0.7397 0.7090 0.6690 0.6490 0.6390 '

7.00 8.00 9.00 10.00 11.00 12.00 l tLLOWABLE A/T 0.6290 0.6190 0.6090 0.4539 0.4539 0.1000 l END OF pc-CRACK I ,

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tm pc-CRACK (C) ~ COPYRIGHT 1984, 1986 STRUCTURAL INTEGRITY ASSOCIATES, INC.

SAN JOSE, CA (408)978-8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION TABLE 24 tLLOWADLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD

!PC g WELD RWCU 6-D-6 WITH SMAW WELDS ALL THICKNESS = 0.4500

[EMBRANE g STRESS =-

4603.0000 ENDZNG STRESS = 4033.0000 XPANSION STRESS = 3849.0000

.IPE OUTSIDE DIAMETER = 6.6280

' LUX WELD TYPE-SMAW(1)/SAW(2)=1 TRESS RATIO = 0.5915 LLOWABLE STRESS =16950.0000 7 LOW STRESS =50850.0000

@ TRESS RATIO IS LESS THAN 0.6000WHICH WILL BE USED IN THE ANALYSIS.

L/ CIRCUM 0.00 0.10 0.20 0.30 0.40 0.50 eLLOWABLE A/T 0.6000 0.6000 0.6000 0.6000 0.6000 0.4900 END OF pc-CRACK q

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m-L i tm pc-CRACK (C) COPYRIGHT 1984, 1986 STRUCTURAL INTEGRITY ASSOCIATES, INC.

SAN JOSE, CA (408)978-8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION TABLE 2-5 tLLOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD

• PC g WELD RWCU 6-D-14 ALL THICKNESS = 0.4500 gEMBRANE STRESS = 4603.0000 ENDING STRESS = 2004.0000 XPANSION STRESS = 5254.0000 IPE OUTSIDE DIAMETER = 6.6280

' LUX WELD TYPE-SMAW(1)/SAW(2)=1 TRESS RATIO = 0.5064

,LLOWABLE STRESS =16950.0000 LOW STRESS =50850.0000

-TRESS RATIO IS LESS THAN 0.6000WHICH WILL BE USED IN THE ANALYSIS.

L/ CIRCUM 0.00 0.10 0.20 0.30 0.40 0.50 tLLOWABLE A/T 0.6000 0.6000 0.6000 0.6000 0.6000 0.4900 END OF pc-CRACK 9

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tm pc-CRACK (C) COPYRIGHT 1984, 1986 STRUCTURAL INTEGRITY ASSOCIATES, INC.

SAN JOSE, CA (408)978-8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION TABLE 2-6'

!LLOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD (PC g WELD RWCU 6-D-17 ALL THICKNESS = 0.4500 EMBRANE STRESS = ' 4603.0000 ENDING STRESS = 2180.0000  !

XPANS20N STRESS = 2456.0000 IPE OUTbIDE DIAMETER = 6.6280 LUX WELD TYPE-SMAW(1)/SAW(2)=1-TRESS RATIO = 0.4525 LLOWABLE STRESS =16950.0000 LOW STRESS =50850.0000

$ TRESS RATIO IS LESS THAN 0.6000WHICH WILL BE USED IN THE ANALYSIS.

L/ CIRCUM .

0.00 0.10 0.20 0.30 0.40 0.50 SLLOWABLE A/T 0.6000 0.6000 0.6000 0.6000 0.6000 0.4900 END OF pc-CRACK i

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2 LAYERS (1)

V, PIPE VALL-PIPE ELBOV li '

L weld centerline LIMITED SERVICE OVERLAY DESIGN

(

REFERENCE:

NUREG-0313 REVISION 2 DRAFT)

( PLANT HATCH UNIT 1 DCR NUNBER 87-128 )

DESIGN FOR VELD NUMBER G31-RVCU-6-D-17

> NOTES:

1. D IGN THICXNESS IS 2 LAYERS AFTER A DYE PENETRANT -

C AN SURFACE .

.' NA N.M EhhRNbTfbN LE S b DEkhb DESIGN NUMBER : SCS-01-0018 REVISION : 1 DATE :S-22-87 l PREPARED BY/ DATE M I N/ G22-se REVIEVED BY/ DATE RIbd/ 5 4-B l

11 FIGURE 2-1

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l- L ._l l = 1. 0" l =1. 0" ! WELD TRANSITION ANGLE (3) ,

(2) ( 2) l

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1. //////D^^/ ,

T = 2 LAYERS (1) !

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'y' PIPE WALL PIPE l ELBDW ,

l- u weld centerline -

-LIMITED SERVICE OVERLAY DESIGN  !

(

REFERENCE:

NUREG-0313 REVISION 2 DRAFT)-

( PLANT HATCH UNIT 1 DCR NUMBER 87-128 ) ,

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l -DESIGN FOR WELD NUMBER G31-RWCU-6-0-6 NOTES:

1. ESIGN TH CKNESS IS 2 LAYERS AFTER A DYE PENETRANT -

2. _:, AN SSR AC AS FUL TH:CKNESS NGTH .

3. 4A I M WE TION AN LE ?S 45 DE EES.

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l-I DESIG!4 NUMBER :. SCS-01-G029 REVISION : 1 DATE :5-22-87 h ,

PREPARED BY/ DATE l 2 D_j.f 22-g7 REVIEWED BY/ DATE J667& yd_s-)2-n f ,

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FIGtJRE 2-2 a

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• l WELD TRANSITION ANGLE (3) !

l(2) l (2,3) l ,/ l l I Y j I, , I

'v! PIPE WALL l  !'

UPSTREAM i DOWNSTREAM (ELBOW) (VALVE) l weld centerline LIMITED SERVICE OVERLAY DESIGN

(

REFERENCE:

NUREG-0313 REVISION 2 DRAFT)

.( PLANT HATCH UNIT 1 DCR NUMBER 87-128 )

DESIGN FOR WELD NUMBER G31-RWCU-6-D-14 NDTES:

1. g N THICKNESS IS 2 LAYERS AFTER A DYE PENETRANT-CLEAN hbh I

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h M T fC Bh bbk T S 3.fA$ MUMED RANSI ION AN E"S450GELSONUPSTREAMSIDE.

O VALV E BL ND TRAN ITLON HE BU"T WEiD CROWN APPROXM;.):LY0.15"FROMVALVE,'T WELDFUSLONLYNE.

DESIGN NUMBER : SCS-01-003B REVISION : 1 DATE : 5-22-87 L PREPARED BY/ DATE N N / r- 2-p REVIEWED BY/ DATEJAG12edu// r-22-77

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13 FIGURE 2-3

3.0 EVALUATION OF FLAWS IDENTIFIED IN RECIRCULATION SYSTEM WELDS During the ultrasonic examination of the weld overlay repairs in place at Plant Hatch Unit 1, new flaw indications were identified in the weld overlay material of two welds (1B31-1RC-28B-4 and 1E11-1RHR-24B-R-12). 'The flaw indications identified in 1987 in the weld overlays on these welds are summarized in Table 3-1 (3).

Indications detected previously at these locations are summarized

. in Table 3-2. It should . be noted that the flaw indications observed in 1986 are confirmed by the most recent examination, although in some cases the character of the flaw has been redefined as a result of the examination by the current version of the inspection procedure. In particular, lowering following the ultrasonic signal to the noise level has resulted in reporting of some flaws which were not reportable in 1986. l Tables 3-1 and 3-2 use the same flaw numbering scheme. An attempt has been made'to correlate the flaw indications observed in 1986 with the indications observed in 1987. The flaw length 1 is included in the tables, as is the depth of the flaw into the overlay (i.e., below the outer surface of the weld overlay). In addition, the azimuthal location of the flaw is reported.

None of the observed flaws in weld overlay-repaired locations f appear to have any connection with the pipe ID, so the flaws do i not represent continued propagation of the underlying IGSCC flaws l into the overlay. All flaws appear to be traceable to  !

fabrication defects in the weld overlay material itself (e.g.,  !

lack of fusion in the first overlay layer), and can therefore be f.

evaluated by the criteria contained in ASME Section XI, IWB-3500

(

(2) for sub-surface planar flaws. Such an evaluation is  !

contained in Appendix A to this report, and it indicates the i

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I observed weld overlay indications to be' acceptable. It should be noted that the as-built thickness of the recirculation weld overlay repairs significantly exceeds the design thickness (as defined in [5]) for these two welds. The required minimum j thickness'is still present outside of the depth of the observed flaws. Consequently, the design function of the weld overlays is not impaired by the presence of the flaws.

In addition to'the flaws identified in the two weld overlays discussed above, two locations which were previously reported to contain flaw indications and which were not repaired but treated by IHSI in 1986, were determined to contain an additional flaw indication. The characterization of the flaw indications in a third unrepaired, IHSI treated location was also revised based upon the detailed inspection performed during the Spring 1987 outage. The flaw indication data for these three locations (1B31-1RC-28A-2, 1B31-1RC-28B-8, M.d 1B31-1RC-28B-10, respectively) are presented in Tables'3-3 (1987) and 3-4 (1986).

These flaws were evaluated in accordance with the requirements of NUREG-0313 Revision 2 (Draft) [1] and ASME Section XI IWB-3641 ]

[4]. All were shown to be acueptable for another operating cycle without repair. All of these locations were treated by IHSI in 1984 or 1985; however, credit for IHSI was not required to demonstrate the acceptability of the above flaw indications for another operating cycle.

I Weld 1B31-1RC-28B-10 contains several distinct flaws, with an aggregate length of approximately 20% of circumference.

NUREG-0313 Revision 2 (Draft) questions the effectiveness of'IHSI ]

l for an aggregate flaw length greater than 10% of circumference.

The flaws in this weld were evaluated assuming that the weld was in the original as-welded condition for the purpose of selecting a . conservative residual stress distribution for use with this 15 i

weld (Figure . 3-1) . The allowable flaw size for the weld was developed using the criteria in IWB-3641-5 Tables, assuming that the original butt weld was made using the SAW or SMAW process (both were ' analyzed) and including the thermal expansion stress in the stress ratio . to determine the allowable flaw size. The I crack growth analysis was conducted in accordance with the guidelines in the NUREG, and demonstrated that the aggregate flaw l will not grow to an unacceptable level in less than 4.5 years, even without the beneficial effects of IHSI. Therefore, the flaws in this weld are acceptable for operation without repair for the next refueling cycle. If the beneficial effects of IHSI were considered, no flaw growth would be predicted. The crack growth results are included in Appendix B to this report.

The conclusion of the study is that the flaws in the weld overlay repairs on welds 24B-R-12 and 28B-4 are acceptable as-is,'without further repair. The flaws in welds 28A-2, 28B-8, and 28B-10 are acceptable for operation without further repair for at least the next fuel cycle.

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i TABLE 3-1

! FLAW INDICATIONS IN WELD OVERLAY MATERIAL -- 1987 1

WELD _ NUMBER FLAW NUMBER LENGTH DEPTH LOCATION (in.) (in.) (CW' inches)2

~1B31-1RC-28B-4 1 0.5 0.6 1.5 - 2.0 1

2 0.38 0.5 9.25 - 9.62 l l

3 0.62 0.46 15 - 15.62 -l I

4 0.5 0.64 17.5 -

5 1.25 0.5 26.5 - 27.75 6 1 0.57- 32 - 33 7- 6 0.46 54 - 60 8 2 0.68 67.75 - 69.75 1E11-1RHR-24B-R-12 1 0.5 0.4 14 l 2 0.7 0.5 35.25 3 1.0 0.4 65.5 NOTE:

1. Depth is measured from outside surface of overlay. The depth i dimension of the indications has been estimated as one overlay l layer or 0.10 in.

2. Location is measured clockwise (CW) from top ~ dead center (0  ;

inches), looking in the direction of flow.

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TABLE 3 FLAW INDICATIONS IN WELD OVERLAY MATERIAL -- 1986 WELD' NUMBER- ' FLAW NUMBER ' ' LENGTH DEPTH LOCATION l (in.) (in.) (CW inches)3

'1B31-1RC-28B-4 1 N/A 2 1.4 0.6 11.4 - 12.8 3 N/A 4 N/A 5 N/A 6 N/A ,

7 1.2 0.58 55.4 - 56.6 8 N/A 1E11-1RHR-24B-R-12 1 N/A 2 1 0.5 0.45 FROM.

UPSTREAM TOE 3 1.5 0.4 65.5

. NOTE:

1. The flaws have been numbered consistent with the results of thel 1987 inspection. .N/A denotes that the flaw so indicated was not detected in 1986.

2.. Depth. is measured from outside surface of overlay. The t actual depth dimension of the indications has been estimated as one overlay layer or 0.10 in.

3. Location is measured clockwise (CW) from top dead center (0 inches), looking in the direction of flow.

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I TABLE.3-3 FLAW INDICATIONS IN WELDS 1B31-1RC-28A-2, 1B31-1RC-28B-8, and 1B31-1RC-28B-10 1987 WELD NUMBER FLAW NUMBER LENGTH DEPTH LOCATION (in.) (%/in.) (CW inches)1 1B31-1RC-28A-2 1 0.9 15%/0.22 7.4 - 8.3 l 1

2 5.2 18%/0.23 8.6 - 13.8 3 1.25 18%/0.27 70 - 71.25

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1B31-1RC-28B-8 1- 0.25 16%/0.2 30 1 2 0.25 16%/0.2 26.5 3 0.3 20%/0.25 AXIAL 21 l 1

-1B31-1RC-28B 1 2.5 24%/0,30 83.75 - 86.25  ;

'l 2 1.0 16%/0.20 87.5 - 88.5 3&4 13.0 16%/0,20 0 - 13.0 l

5 .375 28%/0.35 Axial 84.875 -  !

85.875 6 .375 25%/0.31 Axial 5.0 -

5.5 i

i NOTE:

1.- Location is measured clockwise (CW) from top dead center (0 inches), looking in the direction of flow. ;

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i TABLE 3-4 FLAW INDICATIONS.IN WELDS '1B31-1RC-28A-2, 1B31-1RC-28B-8-and 1B31-1RC-28B-10 1985/1986 WELD NUMBER FLAW NUMBER LENGTH DEPTH LOCATION (in) (%/in.) (CW inches)1 1B31-1RC-28A-2 1 1.0 13%/0.16 7.5 - 8.5 2 5.25 15%/0.19 8.75 - 14 3 N/A 1B31-1RC-28B-8 -1 0.25 24%/0.30 30 i

AXIAL 1 ,

1 2 0.25 16%/0.20 26.5 AXIAL 3 N/A 3B31-1RC-28B-10 1 1.875 23%/0.29 83.5 - 85.4' 2 1.375 20%/0.25 87.625 - 89' 3 2.875 17%/0.21 1.375 - 4.25 4 0.5 15%/0.19 6.75 - 7.25 l 5 Note 2 31%/0.39 Axial 83.625 6 Note 2 26%/0.32 Axial 4.691 NOTE:

1. Location is measured clockwise (CW) from top dead center (0 inches), looking in the direction of flow.

2. Not available.

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4.0 SAFETY EVALUATION 1

I I

.The following section presents the basis for a Safety Evaluation in 10CFR50.59 format to. the extent that- this applies. to Structural-Integrity Associates scope of work. Three statements in the form . used by Georgia Power Company are addressed to facilitate the Safety Evaluation.

1. "The probability 'of occurrences and consequences of an accident or malfunction of' equipment important to safety are not increased above those analyzed in the FSAR". l l

The repairs applied to the reactor . water clean-up system welds do not.. change the operation of the system, nor do they reduce the' structural integrity of the repaired components.-

In fact, the purpose of the repairs.is to insure that the structural integrity of the flawed components is not degraded' with time due . to -intergranular stress corrosion cracking. Consequently, the repairs reduce the probability for an accident, compared to the as-found condition of the components.

2. "The possibility of an accident or malfunction of a different type than analyzed in the FSAR does not result".

Since the operation of the reactor water clean-up system is in no way affected by the repairs, no new mechanism for system malfunction is introduced. The possibility of an accident is reduced compared to the as-found condition, since the observed flaws are arrested by the repair.

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3. "The margin of safety as defined in the basis for any Technical Specification is not reduced".

The repairs and supporting analyses demonitrate that the margins of safety to failure, as defined in the ASME Boiler  ;

and Pressure Vessel Code,Section XI, are maintained by the repairs applied to the reactor water clean-up system. The l analyses further demonstrate that the observed flaws which l were not' repaired do not require any repair to maintain the I code-required margins of safety. Further degradation due to flaw growth is not predicted to occur.

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5.0 CONCLUSION

S Weld overlay repairs were applied to three welds in the reactor water clean-up system at Plant Hatch during the 1987 outage.

These repairs were designed as Limited Service overlays as defined in NUREG-0313, Revision 2 (Draft), and will be replaced or upgraded during the next refueling outage. The overlays are sufficient to further arrest IGSCC flaw growth at the repaired locations, so reduction of the margins of safety at the repaired locations due to continued flaw propagation is not expected.

The flaw characterizations at three locations without existing weld overlay repairs in the 28" portion of the recirculation system were revised in 1987. This is probably due to the refinements in the inspection procedure since the previous inspection (1986). These three locations have all been treated with IHSI. Two of these locations meet the criteria in NUREG-0313, Revision 2 (Draft) for mitigation with IHSI. The third location (weld 1B31-1RC-28B-10) contains a composite flaw with a length which exceeds the NUREG criteria. This flaw has been analyzed in the as-welded condition, and is shown to be acceptable without repair for at least the next operating cycle.

During the examination of weld overlay repaired welds in 1986, several flaws which were embedded in the weld overlay material  ;

were detected. These flaws were apparently due to fabrication defects originating during overlay application (e.g., interpass lack of fusion). When these locations were reinspected in 1987, i- the number and dimensions of these flaws were revised on two

]

welds. The changes are, again, probably due to improvements in '

l the inspection procedures used, and to increased experience on the part of the inspecting personnel, rather than to any real  ;

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change in the actual flaws. The flaw indications in these weld overlays (1B31-1RC-28B-4 and 1E11-1RHR-24B-R-12) were evaluated and shown to be acceptable without repair.

In summary, the flaws detected during the 1987 inspection in the reactor water clean-up and recirculation and RHR systems have been evaluated in accordance with the criteria contained in NUREG-0313, Revision 2 (Draft). Where necessary, repairs have been applied which support operation until the next refueling outage. Unrepaired flaw locations are shown to be acceptable for at least the next operating cycle.  !

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I 6'.O REFERENCES

1. NUREG-0313 Revision 2 (Draft), issued for Public Comment July.11,-1986.

I

'2. General Electric Report, " Plant Piping Analysis" Design Memo

~170-113, September 26, 1984. I

3. Indication Notification Forms (INFs): I87H1010 (Weld-28B-4), I87H1013 '(Weld 24B-R-12), 187H1014 (Weld . 28A-2) , j I87H1015 (Weld 28B-8).

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. 4.- ASME Boiler and Pressure Vessel Code, Section XI, 1983- 1 Edition with Addenda through Winter, 1985. l i

5. Structural Integrity Associates, " Evaluation of IGSCC Flaw Indications and Weld Overlay Designs for Plant E.I. Hatch- l Unit 1 -

Fall 1985/86 Maintenance / Refueling Outage,"

SIR-86-002, Revision 2, April, 1986.=

6. Structural Integrity Associates' Letter JFC-87-015 to Paul d

Norris (GPC), dated May 22, 1987.

7. Structural Integrity Associates, "pc-CRACK" Version 1.1, 1986.

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APPENDIX A Section XI, IWB-3500 Evaluation'of Subsurface Indications'in Weld overlays

'(Welds 1B31-1RC-28B-4 and.1E11-1RHR-24B-R-12) -

I. Weld.1B31-lRC-28B-4 I

Weld . 28B-4 contains 7 flaws in the weld ove'rlay material (see-l Table 3-1). These flaws are concentrated at 2 different axial {

locations. Flaws located _at approximately 3.5 to 3.7" from the l i

upstream toe of the overlay are numbered 2, 3, 4, 5, and 6 in Table 3-1.- The total length of these-flaws is 3.75". The flaws located at approximately 1.6 to 2.0" from the upstream toe of the i

weld overlay are numbered 1, 7, and 8 in Table 3-1. The total length of these flaws is 8.5". The depth a and the planar width W . are unknown: assume a value of 0.1" for each of these dimensions. The total wall thickness of 'the weld at ~ this- i location is approximately 2".

CASE 1: Treat as Laminar Flaw in Accordance With Table IWB-3514-3 2

Flaw Group 1: Total Area = L x W = 0.375 in 2

Flaw Group 2: Total Area = L x W = 0.85 in The allowable area from Table IWB-3514-3 is 4 in2 , which is greater than the observed area for either group.

CASE 2: Treat as Planar Flaws in Accordance With Table IWB-3514-2 a = 0.1" L = 3.75" for flaw group 1

= 8.5" for flaw group 2 {

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so, a/L = 0.03" for flaw group _1 l

= 0.01-for flaw group 2.

l Conservatively treat the flaws as a single flaw with a/L=0.

The corresponding allowable a/t = 10%.

The'as-repaired wall thickness for this weld is approximately;2".

The allowable flaw depth' a is thereforc - 0.2", which is greater -

than the assumed flaw dimension. ] l I

II. Weld 1E11-RHR-24B-R-12 This weld contains 3 flaws with total flaw length = 2. 2" . The

' depth a, and width W dimensions are assumed to be the same as for weld 1B31-28 -4, that is 0.1".

CASE 1: Treat as-Laminar Flaw The calculated area for this composite flaw is 2

Area = L x W = 0.22 in 2

The allowable area is approximately 4 in , from Table IWB-3541-3.

The calculated area is much less than the allowable area for a laminar flaw.

I CASE 2: Treat As A Planar Flaw I For this case, the a/L is determined to be i

t A-2

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a/L = 0.0455 or about 0.05. f Conservatively treat as a/L = 0.0 to enter the IWB-3514-2 Table.

Allowable a/t for a/L = 0.0 a/t = 10% $

For this weld, t is approximately 2.0 inches. Therefore, the allowable a is I i

Allowable a = 0.2"  ;

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which is greater than the assumed value of 0.1". j l

III. Conclusions The flaws observed i. che overlay repairs on welds 1B31-1RC-28B-4 and 1E11-RHR-24B-R-12 are acceptable by the criteria of ASME Section XI, Tables IWB-3514-2 and -3 without further repair.

Since these flaws are not connected to the inside surface of the pipe for these welds as discussed in Section 3 of this report, flaw propagation by IGSCC is not considered to be a concern. It is important to note that the flaws are located in weld overlays, at depths into the overlay material which are greater than the design thickness of the overlay (see Section 3 and Tabls 3-1).

As a result, the effectiveness of the weld overlays is not compromised by the presence of these flaws.

A-3 i

1 t-I APPENDIX B l

Allowable Flaw Size and Crack Growth Calculations (Weld 1B31-1RC-28B-10) 1 I

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(C) COPYRIGHT 1984, 1986 l STRUCTURAL INTEGRITY ASSOCIATES, INC. I SAN JOSE, CA (408)978-8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION TABLE B-1 ALLOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD WELD 2SB-10 ALLOWABLE FLAW SIZE ASSUMING SMAW WELD (

WALL THICKNESS = 1.2500 '

MEMBRANE STRESS = 7028.0000 BENDING STRESS = 2969.0000 ,

EXPANSION STRESS = 652.0000 PIPE OUTSIDE DIAMETER = 28.0000 FLUX WELD TYPE-SMAW(1)/SAW(2)=1 STRESS RATIO = 0.6278 ALLOWABLE STRESS =16950.0000 ,

FLOW STRESS =50850.0000 L/ CIRCUM i 0.00 0.10 0.20 0.30 0.40 0.50 ALLOWABLE A/T O.6000 0.f.000 0.6000 0.6000 0.5722 0.4677 END OF pc-CRACK  !

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'( C ) COPYRIGHT 1984, 1986 STRUCTURAL INTEGRITY ASSOCIATES, INC.

SAN JOSE, CA (408)978-8200 VERSION 1.1 .

l ALLOWABLE FLAW SIZE EVALUATION TABLE B-2 ALLOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD  ;

WELD 2SB-10 ALLOWABLE FLAW SIZE ASSUMING SAW WELD WALL THICKNESS = 1.2500 MEMBRANE STRESS = 7028.0000  ;

BENDING STRESS = 2969.0000 l EXPANSION STRESS = 652.0000 PIPE OUTSIDE DIAMETER = 28.0000 1 FLUX WELD TYPE-SMAW(1)/SAW(2)=2 STRESS RATIO = 0.6737 ALLOWABLE STRESS =16950.0000 FLOW STRESS =50850.0000 L/ CIRCUM 0.00 0.10 0.20 0.30 0.40 0.50 ALLOWABLE A/T 0.6000 0.6000 0.6000 0.6000 0.5310 0.4310 END OF pc-CRACK B-2 i

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(C) COPYRIGHT 1984, 1986 l STRUCTURAL INTEGRITY ASSOCIATES, INC. i SAN JOSE, CA (408)978-8200 VERSION 1.1 STRESS CORROSION CRACK GROWTH ANALYSIS TABLE B-3 l WELD 288-10 IGSCC GROWTH ASSUMING AS-WELDED CONDITION ,

TNITIAL CRACK SIZE = 0.3000 WALL THICKNESS = 1.2500 MAX CRACK SIZE FOR SCCG= 1.0000 STRESS CORROSION CRACK GROWTH LAW (S)

LAW ID C N Kthres K1C NRCSCC 3.5900E-08 2.1610 0.0000 200.0000 STRESS COEFFICIENTS CASE ID CO C1 C2 C3 APPLIED 8.1240 0.0000 0.0000 0.0000 RESIDUAL 30.0000 -193.9500 253.1000 -89.6700 Kmax CASE ID SCALE FACTOR APPLIED 1.00 RESIDUAL 1.00 TIME PRINT TIME INCREMENT INCREMENT 40000.0 732.0 732.0 CRACK MODEL CIRCUMFERENTIAL CRACK IN CYLINDER (T/R=0.1)

CRACK -------------------------STRESS INTENSITY FACTOR----------------------a DEPTH CASE CASE APPLIED RESIDUAL O.0200 2.26 7.72 0.0400 3.21 10.13 0.0600 3.95 11.47  !

O.0800 4.58 12.20 0.1000 5.14 12.52 0.1200 5.66 12.52 ,

0.1400 6.17 12.37 )

, 0.1600 6.67 12.04 j 0.1800 7.16 11.55 l 0.2000 7.63 10.93 l O.2200 8.10 10.19 j O.2400 8.55 9.34 0.2600 9.02 8.45 l

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TABLE B-3 (continued) -

Lpc-CRACK VERSION 1.1 PABE

{

O.2800 9.51 7.52 0.3000 10.01 6.51 0.3200 10.50 5.45 l O.3400 10.99 4.33 0.3600 11.48 3.16 i O.3800 12.00 2.03 )

0.4000' 12.~60 1.05 '

0.4200 13.20 0.06 0.4400 13.82 -0.95 0.4600 14.44 -1.96 0.4800 15.06 -2.98 0.5000 15.70 -3.99 0.5200 16.37 -5.01 0.5400 17.05 -6.02 0.5600 17.74 -7.03 0.5800 18.44 -8.02 0.6000 19.15 -9.01 0.6200 19.86 -9.98 0.6400 20.62 -11.04 0.6600 21.41 -12.13 0.6800 22.21 -13.22 0.7000 23.02 -14.29 0.7200 23.83 -15.36 0.7400 24.65 -16.41 ,

0.7600 25.52 -17.13 l 0.7800 26.43 -17.49 0.8000 27.34 -17.79 0.8200 28.27 -18.02 0.8400 29.20 -18.18 0.8600 30.15 -18.27 0.8800 31.13 -18.55 0.9000 32.19 -19.55 0.9200 33.26 -20.52 0.9400 34.34 -21.44 0.9600 35.43 -22.32 0.9800 36.53 -23.15 1.0000 37.65 -23.92 TIME KMAX DA/DT DA A A/THK 732.0 16.52 1.5385E-05 0.0113 0.3113 0.249 1464.0 16.19 1.4741E-05 0.0108 0.3221 0.258 2196.0 15.88 1.4127E-05 0.0103 0.3324 0.266 2928.0 15.55 1.3511E-05 0.0099 0.3423 0.274 3660.0 15.24 1.2926E-05 0.0095 0.3517 0.281 4392.0 14.92 1.2351E-05 0.0090 0.3608 0.289 5124.0 14.62 1.1817E-05 0.0087 0.3694 0.296 5856.0 14.35 1.1354E-05 0.0083 0.3777 0.302 6588.0 14.09 1.0918E-05 0.0080 0.3857 0.309 7320.0 13.92 1.0623E-05 0.0078 0.3935 0.315 8052.0 13.77 1.0383E-05 0.0076 0.4011 0.321 ,

B-4

pc-CRACK .VERBION 1.1 TABLE B-3 (concluded) PAGE 8784.0 13.63 1.0151E-05 0.0074 0.4085 0.327 9516.0 13.48 9.9212E-06 0.0073 0.4158 0.333 10248.0 13.34 9.6989E-06 0.0071 0.4229 0.338

[ 13.20 9.4829E-06 0.0069 0.4298 0.344 10980.0 11712.0 13.07 9.2722E-06 0.0068 0.4366 0.349

'12444.0 12.93 9.0687E-06 0.0066 0.4433 0.355 13176.0 12.80 8.8719E-06 0.0065 0.4498 0.360 13908.0 12.68 8.6814E-06 0.0064 0.4561 0.365 14640.0 12.55 8.4971E-06 0.0062 0.4623 0.370 15372.0 12.43 8.3196E-06 0.0061 0.4684 0.375 16104.0 12.31 8.1489E-06 0.0060 0.4744 0.380 16836.0 12.19 7.9837E-06 0.0058 0.4802 0.384

( 17568.0 12.08 7.8237E-06 0.0057 0.4860 0.389 18300.0 11.97 7.6722E-06 0.0056 0.4916 0.393 19032.0 11.86 7.5253E-06 0.0055 0.4971 0.398 19764.O' 11.76 7.3826E-06 0.0054 0.5025 0.402 20496.0 11.66 7.2508E-06 0.0053 0.5078 0.406 21228.0 11.57 7.1302E-06 0.0052 0.5130 0.410 21960.0 11.48 7.0127E-06 0.0051 0.5182 0.415 22692.0 11.40 6.8981E-06 0.0050 0.5232 0.419 23424.0 11.31 6.7883E-06 0.0050 0.5282 0.423 24156.0 11.23 6.6824E-06 0.0049 0.5331 0.426 24888.0 11.15 6.5790E-06 0.0048 0.5379 0.430 25620.0 11.07 6.4780E-06 0.0047 0.5426 0.434 26352.0 10.99 6.3816E-06 0.0047 0.5473 0.438 27084.0 10.92 6.2892E-06 0.0046 0.5519 0.442 27816.0 10.85 6.1988E-06 0.0045 0.5564 0.445 28548.0 10.77 6.1104E-06 0.0045 0.5609 0.449 29280.0 10.70 6.0249E-06 0.0044 0.5653 0.452 30012.0 10.64 5.9448E-06 0.0044 0.5697 0.456 30744.0 10.57 5.8663E-06 0.0043 0.5740 0.459 31476.0 10.51 5.7894E-06 0.0042 0.5782 0.463 32208.0 10.44 5.7141E-06 0.0042 0.5824 0.466 32940.0 10.38 5.6431E-06 0.0041 0.5865 0.469 33672.0 10.33 5.5757E-06 0.0041 0.5906 0.472 34404.0 10.27 5.5095E-06 0.0040 0.5946 0.476 35136.0 10.21 5.4445E-06 0.0040 0.5986 0.479 35868.0 10.16 5.3806E-06 0.0039 0.6026 0.482 36600.0 10.11 5.3214E-06 0.0039 0.6065 0.485 37332.0 10.06 5.2650E-06 0.0039 0.6103 0.488 38064.0 10.01 5.2095E-06 0.0038 0.6141 0.491 38796.0 9.96 5.1549E-06 0.0038 0.6179 0.494 39528.0 9.91 5.1012E-06 0.0037 0.6216 0.497 40000.0 9.86 5.0445E-06 0.0024 0.6240 0.499  ;

END OF pc-CRACK 1

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