ML20151G293

Design Rept for Recirculation & Rwcs Evaluations & Repairs Performed During 1988 Refueling Outage at Quad Cities Nuclear Power Plant Unit 2, Vol 2

ML20151G293
Person / Time
Site:	Quad Cities
Issue date:	06/30/1988
From:	Gustin H, Tang S EECSTIA, STRUCTURAL INTEGRITY ASSOCIATES, INC.
To:
Shared Package
ML20151G274	List: ML20151G272 ML20151G288 ML20151G293
References
SIR-88-018, SIR-88-018-V02-R00, SIR-88-18, SIR-88-18-V2-R, NUDOCS 8807280277
Download: ML20151G293 (33)

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l Report No. SIR-88-018, Vol. 2 Revision 0

- Project No. CECO-09Q-1 June, 1988 l

l Volume 2 Design Report for Recirculation and Reactor Water Cleanup System Evaluations and Repairs Performed During the 1988 Refueling Outage at the Quad Cities Nuclear Power Plant, Unit 2 Prepared for:

Commonwealth Edison Company Prepared by:

Structural Integrity Associates, Inc.

San Jose, CA Prepared by: ~

s Date: 3d' 9N i/

f H. ustin f Date: _b 3d, i 3Jf S. T6ny 7

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Reviewed and Approved by: f!'

J. F.

O 8 O IA U /4 land

/ Date:

J 30t7FT Date: " IS 8 8

/D. R. Pitcairn 8807280277 880714 g

{DR ADOCK 0500 65 gg

a Table of Contents Section Pace

1.0 INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . 1-1 2.0 RECONCILIATION OF DESIGN AND AS-BUILT WELD OVERLAY DIMENSIONS . . . . . . . . . . . . .. . . . . 2-1 2.1 Weld Overlay Dimensions. . . . . . . . . . . . . . 2-1 2.1.1 Design of '4 eld Overlays for Welds 02C-S4 and 02H-S4 . . . . . . . . . . . . 2-1 2.1.2 Dimensional Measurements . . . . . . . . . 2-2 2.2 As-Built vs. Design Dimensions . . . . . . . . . . 2-3 3.0 . WELD OVERLAY EXAMINATIONS. . . . . . . . . . . . . . . 3-1 3.1 Introduction . . . . . . . . . . . . . . . . . . . 3-1 3.2 Preservice UT Examination Results. . . . .. . . . 3-1 3.3 Inservice UT Examination Results . . . . . . . . . 3-3 3.4 Conclusions from 1988 Inspection Program . . . . . 3-4 4.0 EVALUATION OF WELD OVERLAY SHRINKAGE INDUCED STRESSES

. . . . . . . . . . . . . . . . . . . . . . . 4-1 4.1 Introduction . . . . . . . . . . . . . . . . . . . 4-1 4.2 Analysis .

. . . . . . . . . . . . . . . . . . . . 4-1 4.3 Acceptance Criteria . . . . . . . . . . . . . . . 4-3

5.0 CONCLUSION

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6.0 REFERENCES

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List of Tables Table Pace 2-1 Summary of Weld Overlair Data - Quad Cities Unit 2 1988 Outage . . . . . . . . . . . . . . . . . . . . 2-4 )

2-2 Summary of Weld Overlay Data - Quad Cities Unit 2 1988 Outage . . . . . . . . . . . . . . . . . . . . . 2-5 3-1 Preservice Ultrasonic Examination Results -

Weld Overlay Repairs - 1988 Refueling Outage -

Quad Cities Unit 2 . . . . . . . . . . . . . . . . . 3-5 3-2 Comparison of Ultrasonic Examination Results -

Quad Cities Unit 2, Previously Applied Weld Overlay Results . . . . . . . . . . . . . . . . . . . . . . . 3-7 3-3 Comparison of Ultrasonic Examination Results - Weld Overlay 02B-S9 . . . . . . . . . . . . . . . . . . . 3-9 4-1 Measured Shrinkage of Weld Overlay Repairs Applied Prior to 1988 . . . . . . . . . . . . . . . . . . . . 4-4 4-2 Weld overlay Shrinkage Induced Stress at Flaw Evaluation Locations . . . . . . . . . . . . . . . . 4-5 4-3 Weld Overlay Shrinkage Induced Stresses in Recirculation Risers: Five Highest Locations . . . . 4-6 4-4 Weld Overlay Shrinkage Induced Stresses in Reactor Water Cleanup System Outside Containmer Three Highest Locations . . . . . . . . . . . . . . . . . . 4-7 4-5 Total Stress at Five Highest Stressed Locations, Including Pressure, Deadweight, Thermal, OBE and Shrinkage . . . . . . . . . . . . . . . . . . . . . . 4-8 ii INTEGRITY ASSOCIATESINC

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List of Figures Em Pacte 4-1 Finite Element Model of Quad Cities Unit 2 Recirculation System . . . . . . . . . . . . . . . . 4-9 4-2 Finite Element Model of Quad Cities Unit 2 Reactor Water Cleanup System . . . . . . . . . . . . . 4-10

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ABSTRACT Volume 1 of this report demonstrates that all analyses and weld overlay repair designs performed in support of the application of weld overlay repairs during the 1988 refueling outage at Quad Cities Unit 2 were in accordance with the requirements of NUREG-0313, Revision 2.

1 This volume provides the reconciliation of the as-built dimensional, nondestructive examination and shrinkage information from the application of these weld overlay repairs. This volume presents documentation that the application of these repairs met all of the criteria and design dimensions.

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1.0 INTRODUCTION

During the.1988 Quad Cities Unit 2 refueling outage, an extensive ultrasonic (UT) examination program of potentially IGSCC susceptible austenitic stainless steel piping weldments was performed. As a result of these examinations, IGSCC or IGSCC-like flaw indications were identified in nineteen (19) welds. These include eleven (11) 12 inch and six (6) 28 inch recirculation system welds, as well as two (2) welds in the 6 inch reactor water cleanup (RWCU) system. Weld overlay repairs were applied to all eleven (11) of the flawed 12 inch recirculation riser welds and both of the flawed 6 inch RWCU piping welds. In addition, weld overlays were applied to two (2) unflawed recirculation riser welds to minimize the effects of weld overlay shrinkage.

The analyses reported in Volume 1 of this report demonstrated the acceptability of the flawed 28 inch welds for continued service.

During the previous refueling outage, a header-to-end cap weld overlay (02A-S10) was applied and UT examined. That UT examination revealed the presence of IGSCC-like flaw indications in the weld overlay material. This weld overlay was re-examined during the 1988 outage. No significant change in the flaw.

indications was observed. The weld overlay was removed by machining and re-applied during the 1988 refueling outage.

Volume 1 of'this report (1) provided:

• the results of detailed analyses of the flawed 28 inch pipe welds, which were performed to justify continued service,in accordance with NUREG-0313, Revision 2,

• the design bases, loading data and design dimensions for the weld overlay repairs applied to the flawed 6 inch RWCU and 12 inch recirculation system weldments, and 1-1 M INTEGRITY ASSOCMTESINC

e a discussion of other technical topics related to the 1988 UT examination program, including a discussion on the evaluation of IGSCC-like flaw indications in IHSI-treated weldmhnts.

Volume 2 provides the data and analytical results which reconcile the as-built dimensions to the design values, and also discusses UT examination results and the evaluation of weld overlay shrinkage data. Section 2.0 of this volume demonstrates that the as-built weld overlay repairs met the dimensional requirements for the standard design basis weld overlay repairs, as defined in Reference 1 and NUREG-0313, Revision 2. Section 3.0 provides a discussion of the examination results, including the preservice UT examination results of the weld overlay repairs applied in 1988 and the inservice UT examination of previously applied weld overlay repairs. Section 4.0 provides the results of stress analyses which evaluate the effects on the affected piping systems of the weld overlay axial shrinkage.

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1 2.0 RECONCILIATION OF DESIGN AND AS-BUILT WELD OVERLAY DIMENSIONS 2.1 Weld Overlay Dimensions The 15 new weld overlay repairs applied during the 1988 Quad Cities Unit 2 refueling outage and the repairs to the 02A-S10 (recirculation header-to-end cap) weld overlay were all designed to meet the "standard" design bases as defined in NUREG-0313 Revision 2. The design bases, analyses and design dimensions for the 13 new weld overlays applied to flawed locations are reported in Volume 1 of this report (1) and are summarized in Table 2-1.

The design information for the 02A-S10 weld overlay repair is contained in (2).

2,1.1 Design of Weld Overlays for Welds 02C-S4 and 02H-S4 In addition to the 13 weld overlays which were applied as repairs in 1988, two weld overlays were applied to unflawed locations (02C-S4 and 02H-S4) to balance and reduce the weld overlay shrinkage stress in the recirculation system. These two weld overlays make the distribution of weld overlays in the system and the associated shrinkage stress more symmetric in the recirculation system, thus reducing the maximum stresses due to shrinkage in the system. The analysis of weld overlay shrinkage stresses is discussed in Section 4.0 of this report.

The weld overlays applied to welds 02C-S4 and 02H-S4 were designed in accordance with NUREG-0313 Revision 2 "standard weld overlays," as were all other weld overlays applied in 1988 (1).

The design widths of these overlays are also consistent with the criteria discuss'ed in Reference (1). Design and as-built dimensi'ns o for these weld overlays are included in Tables 2-1 and 2-2. The stresses used in these designs were:

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1 02C-S4: Pg+PB = 9127 psi 62H-S4: Pg+PB = 8218 psi.

whero the primary memtrane stress Pg is 6811 psi, and the remainder of the above stresses is the primary bending stress P B' This stress information is provided for information only, since these locations were unflawed.

2.1.2 Dimensional Measurements Prior to weld overlay application, each weldment to be repaired is marked with a series of punch marks. These include the center of the weld, the boundary of the weld overlay repair deposit and several sets of witness marks at varic,.ts azimuthal locations.

These witness marks are used to establish a reference location for thickness measurements and to measure the actual axial shrinkage from the overlay repair.

The weld overlay thickness is determined using an ultrasonic thickness gage, typically in four azimuthal locations on both the upstream and downstream sides of the weld overlay repair. In cases where there are geometrical interferences or other obstructions, a minimum of three locations are used. Prior to weld overlay application, the thicknesses at reference locations are measured and recorded. The thicknesses are again measured after the first weld overlay layer, after completion of the welding and after surface conditioning for the preservice UT examination. The original (pre-weld overlay) thickness is subtracted from the final weld overlay thickness. It is the average of these measurements taken after completion of the surface conditioning which is reported in Table 2-2 for each location.

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The width of the weld overlay is determined by actual measurements at the design thickness.

2.2 Comparison of As-Built and Design Dimensions As can be seen from Table 2-2, the as-built thicknesses and widths of the weld overlay repairs applied during -the 1988 Quad Cities Unit 2 outage meet or exceed the design minimum dimensions in all cases.

The average of weld overlay shrinkage for each location is used to analytically determine the effects of this shrinkage on the piping system. The analyses and results are summarized in

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Section 4.0 of this report. No shrinkage measurements were taken for the recirculation header-to-end cap weld overlay due to the fact that the end cap is located at a free end in the system, and any shrinkage at this location would be accommodated by free end displacement. Consequently, the shrinkage at this location would have no effect ut other locations in the' system.

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Table 2-1 Summary of Weld Overlay Data Quad Cities Unit 2 1988 Outage Weld Design Dimensions Number Thickness Length Inches Inches 02C-S4 0.22 4.5 02D-S3 0.22 4.5 02E-S3 0.21 4.5 02F-S3 0.21 4.5 02G-S4 0.21 4.5 02H-S3 0.21 4.5 02H-S4 0.21 4.5 02J-S3 0.21 4.5 02J-S4 0.21 4.5 02K-F6 0.25 4.0 02L-S3 0.22 4.5 02L-S4 0.22 4.5 02M-S4 0.22 4.5 02A-S10 0.38 5.0 12S-S24 0.23 2.4 12S-F26AR 0.20 Note 1 Note 1: Minimum length extends 3/4 inch over adjacent 12S-S26R weld 2-4 Df7EGRITY ASSOCIATES N'

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Table 2-2 Summary of Weld Overlay Data Quad Cities Unit 2 1988 Outage Measured Measured Weld Measured Thickness (In.) Length Shrinkage Number Upstrm. Downstm. Average (In.) (In.)

02C-S4 0.365 0.343 0.354 4.5 0.254 02D-S3 0.316 0.293 0.305 4.8 0.230 02E-S3 0.351 0.366 0.359 4.7 0.215 02F~S3 0.364 0.303 0.334 4.6 0.184 02G-S4 0.319 0.253 0.286 4.6 0.221 02H-S3 0.326 0.346 0.336 4.5 0.318 g

, a 4.6 0.229 02H-S4 0.388 0.313 0.351 02J-S3 0.286 0.380 0.333 4.8 0.200 02J-S4 0.280 0.414 0.347 4.9 0.196 4.1 0.169

! 02K-F6 n/a 0.316 0.316 02L-S3 0.333 0.338 0.336 4.5 0.259 02L-S4 0.346 0.323 0.335 4.5 0.235 02M-S4 0.291 0.348 0.320 4.6 0.241 02A-S10 0.462 0.682 0.572 5.3 n/a 1

2.8 0.378 12S-S24 n/a 0.350 0.350 llI 12S-F26AR 0.352 0.310 0.331 5.9 0.591

, i e-3.0 WELD OVERLAY EXAMINATIONS 3.1 Introduction Mondestructive examinations (NDE), such as visual, Alquid penetrant (PT), and ultrasonic (UT) examinations, are performed before, during, and after the process of applying the weld overlay repair. Prior to welding, the surface to be weld overlay repaired is PT examined to assure freedom from flaws and other material defects which might interfere with the welding.

Visual examination of the surface of the first deposited weld overlay layer and measurement of the amount of delta ferrite in this layer are also performed, along with various other in-process visual inspections for cleanliness during the weld overlay application. In all cases, the as-deposited delta ferrite in the first weld overlay layer exceeded 7.5 FN. This was accomplished by the use of Type 309L welding filler metal containing higher delta ferrite for the first layer of each of the weld overlays applied during this outage.

After completion of the welding, the surface of the weld overlay is conditioned to meet the smoothness and contour criteria established by commonwealth Edison. This improved surface facilitates the preservice UT examination of the completed weld overlay. In addition to the UT examination, a visual examination of the surface and a PT examination of the surface and por' :ons of the base material on either side are also performed. The visual and PT examinations of the completed weld overlays were all acceptable.

3.2 Preservice UT Examination Results The preservice UT examination results for the weld overlay repairs applied during the current 1988 refueling outage are shown in Table 3-1.

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n s-The preservice UT examination results of the eleven (11) weld

. overlays applied to previously flawed 12 inch recirculation riser welds rev9aled flaw indications in eight (8) weld overlay repaired locations. Geven (7) weld overlay examinations revealed axial flaws and one identified circumferential flaws. In all cases, the minimum remaining ligaments reported exceeded the standard weld overlay design thickness, and, in all but one weld overlay exceeded the average as-built thickness, thereby demonstrating no flaws in the weld overlay material for at least the design thickness. In one overlay (02D-S3), the minimum remaining ligament (axial flaw) is less than the average as-built thickness by 0.01 inch, but exceeds the standard design thickness by 0.07 inch.

No reportable indications were observed in cither of the two weld overlayc applied over unflawed welds.

The two 6 inch RWCU weld overlay repairs, while having as-huilt thicknesses which exceed the standard design basis weld ov9rlay, are intended for limited service (one or two fuel cycles).

Therefore, these weld overlay repairs were not surface conditioned and UT examined this outage, due to ALARA concerns.

A large portion of the 22 inch header-to-end cap weld overlay (02A-S10) and a portion of the base material under the weld overlay were removed by machining, and the weld overlay was re-applied during the 1988 refueling outage. The preservice UT examination of this repair revealed several IGSCC-like indications in the base material under the weld overlay, and a large number (approximately 50) of UT indications which were evaluated as "contamination cracks" in the weld overlay material.

Extensive metallurgical examinations of boat samples revealed no crack-like flaws in the weld overlay. Detailed 3D finite element analyses (reported elsewhere) of this weld overlay repair, assuming that these indications are cracks, has demonstrated the 3-2 M

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e acceptability of the repair for continued service. This analysis is discussed in (8).

3.3 InserOlce UT Examination Results Twenty (20) weld overlay rapairs were applied during previous cities Unit 2 outages and are currently in service, Quad rourteen (14) of these were UT examined during the 1988 refueling outage.

Table 3-2 provides a comparison of the current inservice UT examination results with those performed in previous outages. In general the data correlates well and no adverse changes in the weld overlays were observed. However, in UT examination of two previously applied weld overlay repairs, (02B-S9 and 02BS-S3) there are changes in the reported evaluations of thn UT indicat'sns. These two welds are discussed below.

The weld overlay repair on weld 02B-S9 (22 inch recirculation header-to-end cap) was examined in both 1986 and in 1988.

Indications, not in the weld overlay itself, have been observed in both examinations. The details of each examination are shown in Table 3-3. The average thickness of weld overlay 02B-S9 is 0.448 inch.

The observations from the examinations of this weld overlay include:

l l 1. In general, there is an excellent agreement, both in location and remaining ligament, between the 1986 and the l 1988 examinations.

2. In two axial flaw cases, the remaining ligament has decreased, but is still greater than the thickness of the deposited weld overlay.

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The weld overlay repair on weld 02BS-S3 (28" pipe to elbow) was applied in the 1983 refueling outage and was surface conditioned and UT examined in the 1986 outage. This weld overlay has a l design thickness of 0.42 inches and an average as-built tl.ickness of 0.49 inches. No indications were reported in the 1986 examinations of this weld overlay. During the 1988 examination, )

two short circumferential indications were identified:

1. 0.3" long x 0.48" remaining ligament

2. 0.5" long x 0.44" remaining ligament.

The flaws are not connected or in the same plane.

3.4 Conclusions from 1988 Inspection Program The extensive preservice and inservice UT examinations of the weld overlay ropairs at Quad Cities Unit 2 demonstrates the quality of the application process and the acceptability of these repairs for continued service.

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O Table 3-1 Preservice Ultrasonic Examination Results Weld Overlay Repairs - 1988 Refueling Outage Quad Cities Unit 2 Minimum Weld Thickness (In.) Remaining UT Results Number Design Actual Ligament (In.) Flaw Characterization 12 inch Recirculation Riser Welds 02C-S4 0.22 0.35 n/a no reportable indications 02D-S3 0.22 0.30 0.29 axial 02E-S3 0.21 0.36 0.42 axial 02F-S3 0.21 0.33 0.61 circumferential e, 02G-S4 0.21 0.29 0.44 axial 02H-S3 0.21 0.34 n/a no reportable indications 02H-S4 0.21 0.33 n/a no reportable indications 02J-S3 0.21 0.33 0.32 axial 02J-S4 0.21 0.35 0.47 axial 02K-F6 0.25 0.32 0.39 axial 02L-S3 0.22 0.34 0.41 axial 02L-S4 0.22 0.33 n/a no reportable indications 02M-S4 0.22 0.32 n/a no reportable indications 22 inch Recirculation Header Weld

• 02A-S10 Note 1 0.57 Note 2 6 inch Reactor Water Cleanuo Welds 0.23 0.35 Note 3 125-S26R & F26AR 0.20 0.33 Note 3

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Notes to Table 3-1 (1) Minimum full structural (standard) design thickness is 0.33 inch, in accordance with design drawing.

(2) Preservice UT examination results of the repaired 02A-S10 weld overlay reported as several IGSCC-like indications under the weld overlay with minimum remaining ligaments >

design thickness and UT reflectors nvaluated as "contamination cracks" in the weld overlay. Metallurgical examination of several boat samples removed from the overlay did not confirm these to be cracks or other weld metal defects.

(3) These weld overlays are full structural (standard) design bases repairs. Current plans are to replace these weldments within the next two refueling outages, therefore they were not surface conditioned or UT examined for ALARA reasons.

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e Table 3-2 Comparison of Ultrasonic Examination Results

. Quad Cities Unit 2 Previously Applied Weld Overlay Repairs Weld Examination Results Number 1986 1988 28 inch Recirculation 02AS-S4 No flaws in WOR No flaws in WOR (M) 02AS-S9 No flaws in WOR No flaws in WOR (M) 02BD-S6 No flaws in WOR No flaws in WOR (M)

Note 1 02BS-F2 No Flaws in WOR No flaws in WOR (A) 02BS-F7 No flaws in WOR No flaws in WOR (A) 02BS-S3 No flaws in WOR Flaw rl> design thk.

Note 2 (M) 22 inch Recirculation 02B-S9 No flaws in WOR Flaw rl> design thk.

Note 3 (A) 02A-S10 Circumferential No significant Multiple axisls change - Note 4 (A) 12 inch Recirculation 02D-F6 No flaws in WOR No flaws in WOR Note 5 (M) 02F-F6 No flaws in WOR No flavs in WOR (M) 02J-F5 No flaws in WOR No flawn in WOR 02M-F5 No flaws in WOR No flaws in WOR 02M-S3 No flaws in WOR No flaws in WOR (A)

Note 6 20 inch Shitdown Coolina 10S-F5 No flaws in WOR No flaws in WOR (A) = Automated UT Exam (M) = Manual UT Exam r1 = remaining ligament 3-7 ~

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. Notes to Table 3-2 (1) Circumferential flaw 2-3/4 inch long with r1 = 0.58 inch reported on pipe side. Weld overlay thickness in 0.530 inch and design thickness is 0.350 inch.

(2) Two (2) circumferential indications (length = 0.3 inch with r1 = 0. 4 8 inch and length = 0.5 inch with r1 = 0.44 inch).

The average thickness of weld overlay 02BS-S3 is 0.492 inch.

The required minimum design thickness is 0.42 inch.

(3) Eight (8) axit.1 and two (2) circumferential flaws observed in UT examination. The remaining ligaments of all flaws exceed the veld overlay thickness. One (1) axial flaw in low delta ferrite first layer not included in design thickness.

(4) Flawed portion of WOR removed by machining and reapplied during 1988 refueling outage. New UT buseline established.

(5) Axial flaw reported with a r1 = 0.61 inch. As-built weld overlay thickness = 0.329 inch and design thickness = 0.25 inch.

(6) One circumferential flaw on the pipe side (length = 0.6 inch with =r1 = 0.7 inch) and four (4) axials on the elbow side (rl 0.45 inch to 0.7 inch) reported. As-built weld overlay thickness = 0.479 inch (pipe) and 0.331 inch (elbow). The design thickness = 0.25 inch.

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Table 3-3 Comparison of Ultrasonic Examination Results Weld Overlay 028-S9 Circumferential Indications 1986 Examination 1988 Examination Location Length Remaining Length Remaining Ligament, in. Ligament, in.

59.5 2.5 0.60 2.5 0.60 30.5 2.5 0.56 2.5 0.56 Axial Indications 1986 Examination 1988 Examination Location Remaining Location Remaining Ligament, in. Ligament, in.

60 0.55 60 0.55 61 0.58 61 0.58 44 0.60 44 0.46 3 0.62 3 0.50 3 0.70 3 0.70 3.5 0.58 3.5 0.58 7 0.55 7 0.55 7.5 0.60 7.5 0.60 3-9 STRUCTURAL DITEGRITY ASSOCIATEEINC

U 4.0 EVALUATION OF WELD OVERLAY SHRINKAGE INDUCED STRESSES 4.1 Introduction As the weld metal applied during a weld overlay repair solidifies and cools, the weld overlay shrinks axially. This effectively shortens the length of the run of piping in which the repair is situated. This shrinkage produces both axial and bending i stresses at other locations in the piping system. Although this stress is a secondary steady state stress of a type not usually addressed by the Code of Construction, it can have a predicted effect on the growth of flaws at the stressed locations. In addition, stresses of this type may have some effect on initiation of flaws in unflawed locations. Consequently, it is necessary to evaluate the effects of weld overlay shrinkage induced stresses on the repaired system as a whole.

4.2 Analysis In order to evaluate these stresses, a finite element model of the recirculation system from the outlet nozzles to the inlet nozzles was developed. The geometry of the model was taken from (3). The resulting model is illustrated in Figure 4-1. The model was constructed using the commercially available program Supersap [4].

A similar model of the repaired section of the reactor water clean up system was prepared using the same program. This section of RWCU is located outside of the drywell, and is isolated from the recirculation system and other piping inside the dryvell by a rigid anchor point at the drywell penetration.

Consequently, shrinkage in the repaired portion of the RWCU hat:

no effect on stress in the recirculation system. Therefore, the two systems can be treated separately. Figure 4-2 illustrates the RWCU model.

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The as-measured weld overlay shrinkages for weld overlays applied during the 1988 outage were taken from the inspection data (5) and applied to the models shown in Figures 4-1 and 4-2. Table 2-2 lists the shrinkages measured during this outage. In addition, shrinkage values for those overlays which were previously applied to the recirculation system were taken from (2), and are listed in Table 4-1. These values were also incorporated into the finite element model of the recirculation system.

A static stress analysis of each repaired system was performed.

Wold overlay shrinkage was similated by imposing a pseudo-thermal contraction at each overlay repaired element, with the imposed pseudo-temperature determined from the measured shrinkage. The recirculation system model was conservatively assumed to be rigidly anchored at the two outlet end ten inlet nozzles. The stresses calculated by these analyses are summarized in Tables 4-2, 4-3, and 4-4.

Table 4-2 presents the results for those recirculation system locations known to contain flaws which are not weld overlay repaired. Analysis of these locations is contained in Volume 1 of this report. In the Volume 1 flawed pipe analyses, weld overlay shrinkage stress was assumed to be 1000 psi at all locations, since as-built data was not available when that report was written. The shrinkage results at the analyzed locations, as shown in Table 4-2, are less than 500 psi in all cases, so the Volume 1 analyses (1) are conservative with respect to the analysis of as-built weld overlay shrinkage stresses.

Table 4-3 presents weld overlay shrinkage stress results for the five highest stressed locations in the recirculation system, all of which occur in the 12" recirculation risers. Table 4-4 lists the three highest stressed locations in the RWCU system.

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l 4.3 Acceptance criteria There are ,no criteria available for the acceptance of weld overlay shrinkage stresses. For the sake of determining some measure of acceptability for the as-repaired system, the magnitude of the shrinkage stresses from the above analyses were combined with thermal expansion stress, pressure, deadweight, and seismic stresses from (6) and the combination was compared with the primary plus secondary stress limit (3 S ,) from section III of the ASME Code (7). This comparison is presented in Table 4-5 for information. The conclusion of this comparison is that the shrinkage stresses produced by the weld overlay repairs applied previously and during 1988. do not lead to an unacceptably high stress state in the recirculation or RWCU systems. The flaw analyses documented in Volume 1 are not invalidated by these results, since those analyses of flawed locations assumed shrinkage stress of 1000 psi, and the actual values at flawed locations are lower than 500 psi in all cases.

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l Table 4-1 l Measured Shrinkage of Weld overlay Repairs Applied Prior to 19881 Weld Number Shrinkage Amount (In.)

02D-F6 0.108 02F-F6 0.257 02G-53 0.280 02J-F6 0.263 02AS-S9 0.042 02BS-S3 0.063 02BS-F7 0.081 02BD-S6 0.065 10S-F1 0.081 025-F6A 0.287 02M-S3 0.253 02M-F7 0.199 02AS-S4 0.076 10S-F5 0.070 02C-S3 0.203 02K-S3 0.168 02K-S4 0.234 02BS-F2 0.044 1 The values in this Table were taken from (2) 4-4 INTEGRITY ASSOCIATESINC

v o-Table 4-2

,. Weld Overlay Shrinkage Induced Stress at Flaw Evaluation Locations Weld Number Stress (ksi)1 02AD-F12 <0.5 02AD-S6 <0.5 02AS-F14 <0.5 02AS-S12 <0.5 02BD-F8 <0.5 02BS-S12 <0.5 t A value of 1 ksi was assumed in the flaw evaluations presented in Volume 1. These results support that conservative assumption.

N 4-5 INFREUTY ASSOCIATESINC

v Table 4-3 Weld overlay Shrinkage Induced stresses in Recirculation Risers:

Five Highest Locations Weld Location Stress (ksi)

L1 18.8 L2 18.4 D1 12.9 D2 12.7 El 9.7 Note: Weld Numbering Notation:

Letter is riser identifier

1. 1 weld is safe end-to-nozzle weld

1. 2 weld is pipe-to-safe end weld 4-6 M ASSOCIATES LNC

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Table 4-4 Weld overlay Shrinkage Induced Stresses 1

in Reactor Water Cleanup System Outside Containment:

Three Highest Locations Stress (ksi)

1. 6.2

2. 6.0

3. 5.8 Note: Numbers 1., 2., 3., are unrelated to weld numbers, and are intended to show rank only.

4-7 INC

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Table 4-5 Total Stress at Five Highest Stressed Locations, Including Pressure, Deadweight, Thermal, OBE, and Shrinkage Ratio of Weld Total Stress (ksii Total Stress to 3S.

L1 30.6 0.6 L2 30.3 0.6 D1 25.8 0.5 D2 25.6 0.5 El 20.9 0.4 S. is 16.95 ksi for stainless steel at 5500 F (7) i 4-8 g INTEGRITY ASSOCUGEINC

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Y

5.0 CONCLUSION

S Volume 1 of this report discussed the design of weld overlay repairs and flaw evaluation analyses performed during the 1988 refueling outage at Quad Cities Unit 2. Volume 2 compares the design and as-built dimensions of the overlay repairs applied during 1988, evaluates the NDE results of the repaired locations following repair, and discusses the effects of weld overlay shrinkage in the repaired systems. The conclusions from the data and analyses documented in this volume follow.

1. The as-built weld overlay repair thicknesses and lengths meet or exceed the minimum design dimensions in all cases.

2. The preservice ultrasonic examination results for all of the new weld overlays applied this outage are all acceptable.

3. The inservice ultrasonic examination results are generally consistent with the preservice results obtained in 1986, and show no adverse changes.

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4. Results of the analyses of the axial weld overlay shrinkage stresses in both the recirculation and i .CU systems are acceptable.

5. The shrinkages stresses are lower than assumed in volume 1 for evaluation of the six unrepaired, flawed locations in the recirculation system. The analyses of these locations contained in volume 1 are therefore still valid and conservative.

6. The shrinkage stresses at the highest stressed locations in the recirculation and RWCU systems are acceptably low, and no Code limits are violated at these locations.

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ys 6.0- REFERENCES

1. Structural Integrity Associates, "Design Report for Recirculation and Reactor Water Cleanup System Evaluations and Repairs Performed During the 1988 Refueling Outage at the Quad Cities Nuclear Power Plant, Unit 2 Volume 1",

SIR-88-018, Revision 1, May 1988.

2. NUTECH Engineers, "Evaluation and Disposition of Flaws at Quad Cities Nuclear Power Plant Unit 2 (1986 Outage)",

CEC-73-203 Revision 0, January 1987.

3. EDS Nuclear Drawings of the Quad cities Unit 2 Recirculation System:

a. Q2-RRCI-01C "Pump Discharge to RPV" Sheets 1 & 2 Revision 2, July 22, 1981.

b. Q2-RRCI-02C "Recirculation Pump Suction Loop A" Revision 0, July 21, 1981.

c. Q2-RRCI-03C "Recirculation Pump Suction Loop B" Revision 3, July 21, 1981.

4. Algor Interactive Systems, Inc. "Software User Guide for Supersap", 1987.

5. Commonwealth Edison Company Quad Cities Unit 2 Weld Overlay Examination and Shrinkage Measurement Data, 1988

6. Impell Corporation, Portions of Stress Analyses for Quad Cities Reactor Recirculatiou Piping, Superpipe Version 11/15/79, Job Nos. 0590-003 & 013, Problems Q2-RRCI-01C, 02C, 03C, 1981. Structural Integrity File Number Ceco-09-201.

7. American Society of Mechanical Engineers, Boiler and Pressure Vessel Code, Division I, Section III and Appendices", 1986 Edition.

8. Structural Integrity Associates, "Evaluation of End Cap Weld 02A-S10 Weld Overlay Repair Considering Ultrasonic Inspection Findings During 1988 Outage", SIR-88-020, Revision 0, July, 1988.

6-1 6

INTEGRITY ASSOCIATESINC