ML20214S393

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Provides Written Justification for Limited Inservice Insp Scope Expansion & Documents Discussions Provided to NRC During 870520 Telcon.Increased Sample Size for Inservice Insp Adequate to Complete Insp Plan for Outage
ML20214S393
Person / Time
Site: Hatch Southern Nuclear icon.png
Issue date: 05/29/1987
From: Gucwa L
GEORGIA POWER CO.
To:
NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
SL-2575, TAC-64777, NUDOCS 8706090254
Download: ML20214S393 (12)
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Text

l Georgia Fdwer Cornpany 333 Piedmcat Avenue Te on ) 52 6 6 s f x 545 Atlanta, Georgia 30302 Georgia Power -

L T. Gucws "" " * "

  • Manager Nuclear Safety and Licensing '

I SL-2575 1403C X7GJ17-H220 May 29, 1987 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Hashington, D. C. 20555 PLANT HATCH - UNIT 1 NRC DOCKET 50-321 OPERATING LICENSE DPR-57 INSERVICE INSPECTION OF CLASS 1 STAINLESS STEEL PIPING AND COMPONENTS - JUSTIFICATION FOR LIMITED SCOPE EXPANSION AND HELD OVERLAY REPAIR DESIGN Gentlemen:

During Georgia Power Company's (GPC) inspection of Class I stainless steel piping and components, small crack-like indications were discovered

.in two 6-inch diameter Reactor Hater Clean-Up (RHCU) welds. These welds were classified as Category C using the criteria in Draft NUREG-0313, Revision 2, which means that they had no identified IGSCC indications and had been treated with Induction Heating Stress Improvement (IHSI) during the 1985 Unit 1 maintenance / refueling outage. The original inspection plan, submitted to the NRC by letter SL-1951 on February 20, 1987, called for the inspection of 52% of the Category C welds, including nine 6-inch RHCU welds. After the indications were discovered, the NRC (NRR and Region II) was contacted and the scope of the inspection was expanded to include all remaining Category C welds in the RHCU. The expanded scope (eight additional 6-inch welds) yielded an additional weld with small (less than 1-inch in length) circumferential and axial IGSCC-like inM cations. Repairs will be completed this outage for each of the three welas discussed above. Held overlay design information is included in the enclosure.

The inspection plan called for testing 42 Category C welds (about 50%

of the available population) of larger diameter pipe (12" to 28"). No indications were observed. The following provides written justification for the limited ISI scope expansion and documents discussions presented to the NRC by GPC and its consultants (Structural Integrity Associates and Southern Company Services) by phone on May 20, 1987.

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(Ok 8706090254 870529 I '

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PDR G ADOCK 05000321: I PDR

Georgia Powerkh U. S. Nuclear Regulatory Commission May 29, 1987 Page Two After the crack-like indications were reported to the NRC on May 19, 1987, an investigation was conducted to determine the reason for the indications in the thin-walled 6-inch RW'U Category C welds. The investigation showed that changes had been made in the ultrasonic testing procedures since the 1985 maintenance / refueling outage which would increase the detection sensitivity for small indications. These changes included:

1. The minimum overlap in scanning (both circumferentially and axially) had increased from 10% to 25%, thus increasing the probability of detecting small indications.
2. The screen range for each inspection had been broadened, thus spreading the screen presentation.
3. Slower scanning speeds were employed during the current outage.

The result of the increased sensitivity in IGSCC detection means that very small indications which possibly went undetected in the 1985 outage, are currently detectable.

Even with the much improved sensitivity, the inspection results during this outage revealed th&t only short axial and circumferential cracks (less than 1-inch in length) were newly discovered indications.

These short indications are much less significant to the structural integrity of larger diameter (thicker) piping than for the small diameter 6-inch pipe. The expanded inspection scope included 100% of the smaller diameter RWCU pipe Category C welds.

Georgia Power Company had performed a 100% ISI of these Category C welds during the 1985 maintenance / refueling outage. He are committed to inspecting the remaining Category C welds which have not been inspected this outage at the next maintenance / refueling outage, along with all lower category welds. This plan is in accordance with the current Draft NUREG-0313, Rev. 2.

1403C

I GeorgiaPower A U. S. Nuclear Regulatory Commission May 29, 1987 Page Three Based on the above discussion, GPC believes that this _ increased sample size for ISI is adequate to complete the inspection plan for this outage.

The design information for the three RHCU weld overlays is discussed in the enclosure. Georgia Power Company considers these designs to be adequate for limited service, per Draft NUREG-0313, Rev. 2.

If you have any questions in this regard, please contact this office at any time.

Sincerely,

/TQ m L. T. Gucwa GKH/lc

Enclosure:

Design Information for Three RHCU Limited Service Held Overlays - 1987 Unit 1 Maintenance / Refueling Outage c: Georaia Power Company Mr. J. P. O'Reilly, Sr. Vice President - Nuclear Operations Mr. J. T. Beckham, Jr., Vice President - Plant Hatch GO-NORMS U. S. Nuclear Reaulatory Commission. Washinaton. D. C.

Mr. L. P. Crocker, Licensing Project Manager - Hatch U. S. Nuclear Reaulatory Commission. Region II Dr. J. N. Grace, Regional Administrator Mr. P. Holmes-Ray, Senior Resident Inspector - Hatch 1403C 70071$

GeorgiaPower d ENCLOSURE PLANT HATCH - UNIT 1 NRC DOCKET 50-321 OPERATING LICENSE DPR-57 DESIGN INFORMATION FOR THREE RHCU LIMITED SERVICE HELD OVERLAYS - 1987 UNIT 1 MAINTENANCE / REFUELING OUTAGE As noted in the letter, all the Category C welds in the Class 1 RHCU piping were inspected following the scope expansion. Three of the 17 welds have short IGSCC-like indications and will be repaired by Limited Service weld overlay. Figure 1 depicts the Class 1 RHCU piping, and shows the 4 welds which were overlayed during the 1985 outage. Also included are the subject Limited Service Overlay design sketches (per Draft NUREG-0313, Rev. 2) and computer runs (pc-CRACK) for the reported indications in the three welds.

The pc-CRACK runs 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 IHB 3641 tables (Hinter 85 Addenda) for SMAH welds. Stresses are based on the GE stress report for the RHCU line. The maximum reported circumferential indication size for the RHCU is 55% of wall by 0.7" long in this 6.628" OD pipe, and the maximum axial 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 resiaual stresses at the indications and to provide leak barriers. The 2-layer thickness (after PT-clear surface) is considered adequate for this purpose. The width whichofisthe overlays greater for 1.5 than the pipe

[RT]1/2 elbow welds (6-D-6 and 6-D-17) is 2",

- 1.5 [(3.314) (.45)]1/2 - 1.83" (the criterion for previous overlays, exclusive of UT requirements which are not a factor for limited service). The 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.

1403C E-1 5/29/87 SL-2575 700775

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weld centerline LIMITED SERVICE OVERLAY DESIGN (REFERENCEi NUREG-0313 REVISION 2 DRAFT)

( PLANT HATCH UNIT 1 DCR NUMBER 87-128 )

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

NDTES:

1. DESIGN THICKNESS IS 2 LAYERS AFTER A DYE PENETRANT -

CL AN SURFACE .

2. LEIGT-ISSPECIFIEDASFULLTHLCKNESSLENGTH.
3. MAXIM _M WELD TRANSITION ANGLE iS 45 DEGREES.

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l DESIGN NUMBER : SCS-01-0028 REVISION : 1 DATE :5-22-87 PRFPARED BY/ DATE M I d / n 22-97

REVIEWED BY/ DATE J/I674d M/ f-a-f7 l

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REFERENCE:

NUREG-0313 REVISION 2 DRAFT)

( PLANT HATCH UNIT 1 DCR NUMBER 87-128 )

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

1. DESIGN THICKNESS IS 2 LAYERS AFTER A DYE PENETRANT-CLEAN SURFACE.
2. LENGTH IS SPECIFIED AS FULL THICKNESS LENGTH . REPAIR IS ASYMMETRIC BECAUSE OF THE CAST VALVE BODY.

O VhSDE ND T t S T ON N0 BbT APPROXIMA"ELY 0.125" Fh0M VALVE "O W B

DESIGN NUMBER : SCS-01-003B REVISION : 1 DATE : 5-22-87 PREPARED BY/ DATE M I b l / f-z2-8'7 REVIEWED BY/ DATEJ66f2gdj/ 5:22 $?

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REFERENCE:

NUREG-0313 REVISION 2 DRAFT)

( PLANT HATCH UNIT 1 DCR NUMBER 87-128 )

DESIGN FOR WELD NUMBER G31-RWCU-6-D-17 NOTES:

1. DESIGN THICKNESS IS 2 LAYERS AFTER A DYE PENETRANT -

CLEAN SURFACE ,

b:bfNN E hkANbTfbN bLE S b DEbkhS DESIGN NUMBER : SCS-DI-0018 REVISION : 1 DATE :5-22-87 PREPAREDBY/DATEMI / o z2-sp REVIEWED BY/ DATE J/ fg24d// P2Wp

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E-s 5/29/87

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

SAN JOSE, CA (408)978--8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION ALLOWABLE FLAW SIZE FOR CIRCUt1F. CRACK, FLUX WELD GPC, RWCU 6-D-6 WALL THICKNESS = 0.4500 MEMBRANE STRESS = 4603.0000 BENDING STRESS = 4033.0000 EXPANSION STRESS" 3849.0000 PIPE OUTSIDE DI At1ETER== 6.6280 FLUX WELD TYPE-SMAW(1)/SAW(2)=1 STRESS RATIO = 0.5968 ALLOWABLE STRESS =16800.0000 FLOW STRESS =50400.0000 STRESS RATIO IS LESS THAN O.6000WHICH WILL BE USED IN THE ANALYSIS.

L/ CIRCUM i O.00 O.10 0.20 0.30 0.40 0.50 ALLOWABLE A/T O.6000 0.6000 0.6000 0.6000 0.6000 C.4900 END OF pc-CRACK Prepared by;U W d 5-2/~f 7 Checked by: k k M f-22-F7 File No. SCS- 02 Page of E-6 5/29/87

. o tm pc-CRACK (C) COPYRIGHT 1984, 1986 STRUCTURAL INTEGRITY AS5OCIATES, I f1C.

SAN JOSE, CA (40EO978-82OO VERSION 1.1 ALLOWABLE FLAW S17E EVALUATION ALLOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD GPC, RWCU 6-D-14 WALL THICKNESS = 0.4500 MEMBRANC STRESS: 4603.0000 BENDING STRESS = 2084.0000 EXPANSION STRESS = 5254.0000 PIPE OUTSIDE DIAMETER = 6.6280 FLUX WELD TYPE-SMAWf1)/SAW(2)=1 STRESS RAT 10= 0.5109 ALL.OWABLE STRESS =16800.0000 FLOW STRESS =50400.OOOO STRESS RATIO IS LESS THAN O.6000WHICH WILL BE USED IN 1~HE ANALYSIS.

L/ CIRCUM O.00 O.10 O.20 0.30 0.40 0.50 ALLOWABLE A/T O.6000 0.6000 0.6000 0.6000 0.6000 0.4900 END OF pt-CRACK Prepared by:M @M &#f.u17 Checked by: S - M Q r-22-g7 File No. 5CS~02 Pa0e of E-7 5/29/6/ -

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

SAN JOSE, CA (408)979-8200 VERSION 1.1 ALLOWABLE FLAW SIZE EVALUATION Ai.LOWABLE FLAW SIZE FOR CIRCUMF. CRACK, FLUX WELD GPC, RWCU 6-D-17 WALL THICNNESS= 0.4500 MEMBRANE STRESS = 4603.0000 BENDING STRESS = 2180.0000 EXPANSION STRESSu 2456.0000 PIPE OUTSIDE DIAMETER = 6.6280 FLUX WELD TYPE-SMAW(1)/SAW(2)=1 STRESS RATIO = 0.4565 ALLOWADLE S1RESS=16800.0000 FLOW STRESS =50400.0000 STRESS RATIO IS LESS THAN 0.6000WHICH WILL BE USED IN lHE ANALYSIS.

L/ CIRCUM O.00 0 10 0.20 0.30 0.40 9.50 ALLOWADLE A/T 0.6000 0.6000 0.6000 0.6000 0.6000 0.4900 END OF pc-CRACK l

Irepared Checked by:

by:[W A- UW'WP'I~N f.22-g7 File No. S C S - 0 2.

Page of E-8 2/29/87

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

SAN JOSE, CA (408)978-8200 VERSION 1.1- 1 ALLOWABLE FLAW SIZE EVALUATION t ALLOWABLE FLAW SIZE FOR AXIAL CRACK, WROUGHT / CAST STAINLESS '

GPC, RWCU 6-D-14

(#MM b ~~3 ~b WALL THICKNEES= 0.4500 MEMBRANE STRESS = 7364.0000 STRESS RATIO = 0.4383 -

ALLOWABLE STRESS =16800.OOOO FLOW STRESS =50400.OOOO L/SQRT(RT) 0.00 0.50 1.00 2.00 3.00 4.00 5.00 6.00 ALLOWABLE A/T O.7500 0.7500 0.7500 0.7385 0.7055 0.6655 0.6455 0.6355 7.00 8.00 9.00 10.00 11.00 12.00 ALLOWABLE A/T O.6255 0.6155 0.6055 0.4330 0.4330 0.1000 END OF pc-CRACK T

Prepared by: (M bI #'

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Checked by:

File No. SCS-02 Page of E-9 5/29/87

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