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ATTACHMENT

Consumers Power CompanyPalisades PlantDocket 50-255

WELD OVERLAY REPAIRS OF CONTAINMENT SUMP CHECK VALVESFOLLOW-UP INFORMATION

July 15, 1994

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9407250324 940715PDR ADOCK 05000255P pop ,

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0054-o01o1-001-11oRevision 1

VECTRA 0054.00101.001.110 '

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FINAL REPORT

CONTAINMENT SUMP CHECK VALVES ''

WELD OVERLAY REPAIRIMPLEMENTATION EVALUATION

PALISADES NUCLEAR PLANT

Prepared for: ;

Consumers Power Company (

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Prepared by:

VECTRA

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Reviewed by: Issued by:

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Carl H. Froehlich, P.E. Dale L. Jor/sEngineering Manager Project M4 nager

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Date: 14 ZIy I'IfY 't

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REVISION CONTROL SHEET.c ,.

TITLE: Final Report - Containment Sump DOC. FILE NO.: 0054.00101.001.110Check Valves Weld Overlay RepairIrT.plementation Evaluation -Palisades Nuclear Plant

Carl H. Froehlich / Staff Engineer CMMlNAME/ TITLE INITIALS

James W. Axline / Staff Engineer On File

NAME/ TITLE INITIALS

James A. Brown / Staff Engineer [-INAME/ TITLE INITIALS

NAME/ TITLE INITIALS

AFFECTED DDC. PREPARED ACCURACY CRITERIAPAGE(S) REV. BY/DATE CHECK BY/DATE CHECK BY/DATE REMARKS

iii - v 0 On File On File On File issued for use.

1 - 38 0 " " *

CA/J /4/g4 T/ft/g 7/#9/p Corrected typo.715 117 & 18 1 incorporated CPCo comment.

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21 - 23 1 |"

25 & 28 1 W Corrected typo.

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TABLE OF CONTENTS |

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LIST OF TABLES iv

LIST OF FIGURES v ,l

1.0 INTRODUCTION 1

2.0 OVERLAY IMPLEMENTATION REQUIREMENTS 6,

l2.1 ASME Section XI Repair Program 6 12.2 Overlay Material and Application Requirements 6 '2.3 Original Pipe Surface Liquid Penetrant Examination 72.4 Original Pipe Surface Repair / Seal Layer PT Examination 82.5 Minimum 2 Layer Thickness 8 l2.6 Ferrite Content 92.7 NDE Access 9 ,2.8 Overlay Design 9 l2.9 Repaired Weldment/ Component and System Evaluation 10 |2.10 Pressure Testing 102.11 Preservice Examinations 102.12 Piping System Support Examination and Other 11

Applicable Requirements I2.13 Code Case Documentation 11

3.0 AS-BUILT OVERLAY GEOMETRY 14 ']

4.0 VOLUMETRIC UT INDICATIONS EVALUATION 17

5.0 OVERLAY WELDMENT AND SYSTEM AFFECTS 25

5.1 Weidment Evaluation 25 !5.2 System Evaluation 28

6.0 SUMMARY AND CONCLUSIONS 35

7.0 REFERENCES 36'

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LIST OF TABLES

Number M Paae

2.6-1 CK-ES3166 and CK-ES3181 Minimum Ferrite 12Content Measurements

3.0-1 As-Built Weld Overlay Repair Thicknesses 15

3.0-2 As-Built Weld Overlay Repair Widths 15

3.0-3 As-Built Weld Overlay Repair Axial Shrinkages 16

4.0-1 Allowable Volumetric Preservice Examination 24Planar Flaws

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LIST OF FIGURES

Number Titic Paga

1.0-1 General Layout of Containment Sump Check Valves 2

1.0-2 CK-ES3166 Check Valve-to-Tee Pre-Weld Overlay 3Repair Indication Roll-Out Map

1.0-3 CK-ES3181 Check Valve-to-Tee Pre-Weld Overlay 4Repair Indication Roll-Out Map

1.0-4 CK-ES3166 and CK-ES3181 Check Valve-to-Tee 5Pre-Weld Overlay Repair Cross-Section

2.8-1 Weld Overlay Repair Design Dimensions 13

3.0-1 As-Built Weld Overlay Repair Thickness Measurement 10Locations

4.0-1 CK-ES3166 Check Valve-to-Tee Post-Weld Overlay 21Repair Indication Roll-Out Map

4.0-2 CK-ES3181 Check Valve-to-Tee Post-Weld Overlay 22Repair Indication Roll-Out Map

4.0-3 Surface and Subsurface Planar Flaws 23

5.1-1 Typical Post-Overlay Axial Residual Stress Conditions 30 ||

5.1-2 Carbon vs. Ferrite Content Affects on IGSCC Resistance 31 ||

5.1-3 Boat Sample Metallographs 32 |

5.2-1 CK-ES3166 Piping System Layout 33

5.2-2 CK-ES3181 Piping System Layout 34

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1.0 INTRODUCTION

A leak leading to the shutdown of Consumer Power Company's iCPCo)

Palisades Nuclear Plant (PNP) was identified in a check valve (CK-ES3166)

in the auxiliary building west engineering safeguards room on February 17,

1994. Subsequent nondestructive examinations also identified indications

in another check valve (CK-ES3181) and additional indications in valve

CK-ES3166. In the Reference 1 system diagram, these valves are part of

the Engineering Safeguard System (ESS ; Safety injection, Containment

Spray, and Shutdown Cooling Systems). The generallocation of these

valves is shown in Figure 1.0-1. As shown in Figures 1.0-2 through 1.0-4,

the identified indications are located in the downstream end of the check

valves which are each welded to a 24" x 24" x 14" tee fitting.

As discussed in the Reference 2 evaluation report, "use as-is", spool piece

replacement, and weld overlay repair alternatives were considered for the

repair of the check valve-to-tee weldments. In early March, a weld overlay

repair meeting the requirements of American Society of Mechanical

Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Case N-504-1

(Reference 3) was selected as the repair alternative.

This report presents an evaluation of the implemented weld overlay repairs.

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SAFETYINJECTION

&REFUELINGWATERTANK

(1) TO HP & LP SAFETY INJECTION &CONTAINMENT SPRAY PUMPS

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CONTAINMENT_

SUMP_

1(1)

4 __ (1)A :

_L3181 CONTAINMENT

4 f >< || T-' PENETRATIONS'4, N a' >4 !! -

3166

24' x 24' x 14*TEE V i

(1)

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Figure 1.0-1

GENERAL LAYOUT OF CONTAINMENT SUMPCHECK VALVES

(Reference 1)

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A l8.7 k WELD

- >/ REPAIRS(#)C /*,,excL, 2.2' @'/_b#7* @__. __ @ M VALVE

J.W L i@ @) n@ I/ On4 i,,

bh |_t i i i in i in jCo- lis l (32.75 1 [43.37s1 181.2s-| 175.s-| g

@ |36 l 14s.51 [W.Fj TEE|37.37s1 146.251 | 77.7-|

(3166 RAW.WPG) |48.s1

NOTES:

1. Detected leakage occurred at Indication No. 8.2. All indications were detected during volumetric UT.3. Indications 1,8, and 9 were also detected during

radiographic examination.|

4. Original construction repairs of valve body.

Figure 1.0-2,

|CK-ES3166 CHECK VALVE-TO-TEE |

PRE-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP(Reference 4)

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A

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(if I45 2'DE)y VALVE

@ i =s .@ @' y || i @ t

$ / yI il I ! I i | |0" |6.8751 148.375j 159.51 |68.875 75.751 y

|0.751 |7.751 |70.751 TEE

(3181 FLAW.WPG)

NOTE: All indications were detected during volumetric UT.

Figure 1.0-3

CK-ES3181 CHECK VALVE-TO-TEEPRE-WFLD OVERLAY REPAIR INDICATION ROLL-OUT MAP

(Reference 4)

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VALVE * - . TEE

f. WELDREGION *C'

REGION *B'__

REGION *A'

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Figure 1.0-4

CK ES3166 AND CK-ES3181 CHECK VALVE-TO-TEEPRE-WELD OVERLAY REPAIR CROSS SECTION

(Reference 4)

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2.0 OVERLAY IMPLEMENTATION REQUIREMENTS:

The weld overlay repairs applied to the CK-ES3166 and CK-ES3181 check

valve-to-tee weldments were implemented in accordance with thes

following requirements of Code Case N-504-1 (Reference 3).

2.1 ASME Section XI Reoair Proaram.

Code Case N-504-1 Paragraph (a) requires the implementation of weld

overlay repairs in accordance with a Repair Program satisfying the

requirements of ASME BPVC Section XI, Subsection IWA-4000.

Accordingly, the Reference 5 Repair Program was prepared to detail

currently applicable and original construction codes; flaw removal methods;

gensral weld overlay repair application, design, implementation

documentation, and permanent record requirements; nondestructive

examination (NDE) and system pressure testing requirements; and form ;

NIS-2 documentation requirements.

2.2 Overlav Material and Acolication Reauirements

Code Case N 504-1 Paragraph (b) requires that weld overlay repair filler

metal have a maximum carbon content of 0.035%, be applied 360*

circumferentially around a weldment, and be deposited in accordance with

a qualified welding procedure specification. Accordingly, the Reference 6

application and examination procedure was used to control theo

I implementation of weld overlay repairs on the CK-ES3166 and CK-ES3181

i check valve-to-tee weldments.

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As required by the Reference 7 purchase order, all filler metals used during

machine Gas Tungsten Arc Welding (GTAW) for the application of the joverlays or manual GTAW or Shielded Metal Arc Welding (SMAW) for

original pipe surface or overlay repairs were permitted a maximum carbon

content of 0.030%. The Reference 6 procedure also required the

following: !

a. Application of overlays using parallel, overlapping,360

circumferential beads around a weldment.

b. The use of ASME BPVC Section IX qualified welders, welding

operators, and welding procedure specifications,

c. Overlay application with water inside the weldments,

d. A maximum allowable "interpass" temperature of 212 F.

e. A maximum heat input of 28 Kjoules/ inch for at least the first two

design (structural) layers of an overlay.

2.3 Oriainal Pioe Surface Liauld Penetrant Examination

Code Case N-504-1 Paragraph (c) requires that the original pipe surface be

examined by the liquid penetrant (PT) examination technique with a

maximum indication acceptance criteria of 1/16" before application of a

weld overlay repair. The Code Case goes on to require the repair of

unacceptable indications by either excavation / repair welding or the

application of one or more " seal" layers that are not to be included in the1'

weld overlay repair design thickness.

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The leaking flaw discovered in the CK-ES3166 check valve-to-tee

weldment was excavated and repair welded prior to overlay application.'

Due to other PT indications in the weld overlay repair areas on the original

pipo surface of both weldments that exceeded a zero tolerance size

acceptance criteria required by the Reference 6 application and

examination procedure, a seal layer was applied to each weldment. The

seallayer covered the excavation repair in the CK-ES3166 weldment.

As shown in Section 3.0, the seal layer thicknesses have not been

included in the weld overlay repair design (structural) thicknesses.

2.4 Orlainal Pioe Surface Repair / Seal Laver PT Examination,

Code Case N-504-1 Paragraph (d) requires that any excavation repairs or

seal layers applied over the original pipe surface also be examined by the

PT examination technique with a maximum indication acceptance criteria*

of 1/16". The seal layers applied to the CK-ES3166 and CK-ES3181

weldments were PT examined and found acceptable per a zero tolerance

size acceptance criteria required by the Reference 6 application and

examination procedure (References 8 and 9).

2.5 Minimum 2 Laver Thickness j|

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Code Case N-504-1 Paragraph (e) requires that a weld overlay repair be

constructed of a minimum of two layers. Section 3.0 presents the seal

layer, design (structural) weld overlay repair, and total overlay thicknesses i

for the CK-ES3166 and CK ES3181 weldments.

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2.6 Ferrite Content I

Code Case N-504-1 Paragraph (e) also requires that the first layeri

considered to be part of the design (structural) weld overlay repair '

thickness shall have a minimum ferrite content of 7.5 FN without requiring - ;further evaluation. As shown in Table 2.6-1, all ferrite content I

measurements for the first two design (structural) layers of the CK-ES3166

and CK-ES3181 overlays exceeded 7.5 FN.,

2.7 NDE Access

Code Case N-504-1 Paragraph (f) requires that an overlay's geometryI

provide access for PT and volumetric ultrasonic (UT) examination. The

weld overlay repairs applied to the CK-ES3166 and CK-ES3181 check

valve-to-tee weldments permit access for PT and volumetric UT as

illustrated by the NDE results reported through-out this evaluation report.

2.8 Overlav Desian,

The Reference 4 calculation package presents the design of the weld

overlay repairs for the CK-ES3166 and CK-ES3181 check valve-to-tee

weldments. The overlays were designed in accordance with Paragraph (f)

of ASME BPVC Case N-504-1 (Reference 3) and Paragraph IWB 3640 of

ASME BPVC Section XI (Reference 10). Figure 2.8-1 presents the design

weld overlay repair geometries..

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2.9 Reoaired Weldment/Comoonent and System Evaluation

Code Case N-504-1 Paragraph (g) requires an evaluation of a repaired

weldment/ component and the repair's affect on other weldments and

components within the repaired weldment/ component's piping system.

For the CK-ES3166 and CK-ES3181 check valve-to-tee weld overisy

repairs, an evaluation of these concerns is presented in Section 5.0.

2.10 Pressure Testino

Code Case N-504-1 Paragraph (h) requires that a completed overlay be

pressure tested in accordance with ASME BPVC Section XI, Subsection

IWA-5000. As required by the Reference 5 Repair Program, the

CK-ES3166 overlay applied over the leaking flaw discussed in Section 1.0 '

was hydrostatically tested. In addition, even though it was applied over

indications that did not penetrate the pressure boundary, the CK-ES3181 -

overlay was also hydrostatically tested.

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2.11 Preservice Examinations

Code Case N-504-1 Paragraphs (i) and (j) require that a completed overlay

be examined using PT techniques and the overlay and the outer 25% of

the original pipe wall be examined using volumetric UT techniques prior to

being placed in service. The weld overlay repairs applied to the

CK-ES3166 and CK-ES3181 check valve-to-tee weldments were examined

using PT and volumetric UT techniques. All PT indications were evaluated

by PNP personnel and found to meet the acceptance standards of ASME

BPVC Section XI Table IWB-3514-2 (References 11 through 14). All UT

indications are addressed in Section 4.0.

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2.12 Pinina System Sucoort Examination and Other Acolicable Recuirements

Code Case N-504-1 Paragraph (k) requires a VT-3 examination of piping

system restraints, supports, and snubbers affected by the weld overlay

repair activities. To provide access for the application of the CK-ES3166

check valve-to-tee overlay, a spring hanger had to be removed. This

hanger received a VT-3 examination after reinstallation.

Code Case N-504-1 Paragraph (1) states that the requirements of ASME

BPVC Sections IWA-4000, IWB-4000, IWC-4000, and IWD-4000 shall

also be met during overlay application. Because the ESS is currently

treated as an ASME Class 2 system not subject to IWD-4000, the

applicable requirements of Sections IWA-4000, IWB-4000, and IWC-4000

were met.

2.13 Code Case Documentation

Code Case N-504-1 Paragraph (m) requires weld overlay repairs applied in

accordance with N-504-1 be documented on an NIS-2 form. As required

by the Reference 5 Repair Program, the CK-ES3166 and CK-ES3181 check

valve-to-tee weld overlay repairs have been duly documented.

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Table 2.6-1

CK-ES3166 AND CK-ES3181MINIMUM FERRITE CONTENT MEASUREMENTS

(References 15 and 16)

CK ES3166 CK-ES3181

First Valve Side 12.5 FN 12.5 FNDesignLayer Tee Side 12.5 FN 10 FN

Second Valve Side 12.5 FN 12.5 FN|Design

Layer Tee Side 12.5 FN 12.5 FN|

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i WELD

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M == M 45 min.| NOTE 2 , | (tyP-),

=f S. t-'

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WELD OVERLAY REPAIR DIMENSIONSVALVE

NO.t,(1) A B

CK-ES3166 0.20" 4.6" 2.0"

CK-ES$181 0.19" 4.4" 2.0"

NOTFJ:

(1) t, = minimum design thickness.(2) Final contour based upon volumetric UT examination requirements.

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Figure 2.8-1 |

WELD OVERLAY REPAIR DESIGN DIMENSIONS(Reference 4)

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3.0 AS-BUILT OVERLAY GEOMETRY |l|

Per the requirements of the Reference 6 application and examination

procedure, Weld Overlay Data Sheets (References 17 and 18) were used

to document the following weld overlay repair information for the CK-

ES3166 and CK-ES3181 check valve-to-tee weldments: ;l!

a. The original pipe wall, seal layer, design (structural) weld overlayi

repair, and total weld overlay repair thicknesses (Table 3.0-1).

b. The final shoulder-to-shoulder width of the overlay (Table 3.0-2). ,I

c. The first and second design (structural) layer ferrite content i

measurements (Table 2.6-1),

Id. The weld overlay axial shrinkage (Table 3.0-3).

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The thicknesses shown in Table 3.0-1 were measured as shown in Figure

3.0-1. ll

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A comparison of the design (structural) overlay thicknesses presented in l:

Table 3.0-1 and the shoulder-to-shoulder overlay widths presented in Table

3.0-2 with the design weld overlay repair geometries presented in Figure

2.8-1 shows that the as-built geometries conservatively meet the design

geometries. Therefore, the as-built weld overlay repairs meet the

requirements of Paragraph (g) of ASME BPVC Case N-504-1 (Reference 3)

and Paragraph IWB-3640 of ASME BPVC Section XI (Reference 10). |

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Table 3.0-1

AS-BUILT WELD OVERLAY REPAIR THICKNESSES(References 17 and 18)

CK-ES3166 CK-ES3181

Avg. Original Pipe Wall 0.70" O.73"Thickness (A)

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Avg. Pipe Wall + Seal 0.79" 0.80"Layer Thickness (B)

Avg. Seal Layer 0.09" 0.07"Thickness (C = B - A)

Avg. Pipe Wall + Total 1.54" 1.64"Overlay Thickness (D)

Avg. Total Overlay 0.84" 0.91"Thickness (E = D - A)

Avg. Design (Structural) 0.75" O.84"Overlay Thickness(F = D - 8)

Table 3.0-2

AS-BUILT WELD OVERLAY REPAIR WIDTHS(References 17 and 18)

CK-ES3166 CK-ES3181

Avg. Shoulder-to- 6.7" 6.6"Shoulder OverlayWidth '

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Table 3.0-3

AS-BUILT WELD OVERLAY REPAIR AXIAL SHRINKAGES(References 17 and 18)

AVG. WITNESS MARK-TO-CK-ES3166 CK-ES3181WITNESS MARK DISTANCE

Before Overlay (A) 9.55" 9.38"

After Overlay (B) 9.33" 9.05"

Avg. Overlay Shrinkage 0.22" 0.33"(C = B - A)

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( WELDSEAL LAYER THICKNESS

_ MEASUREMENTS

h = 2.25' _,i ;

L | | -= r ,=& -- ' . jo

x , .,.

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WTTNESS MARKS (twow.m1 m

Figure 3.0-1

AS-BUILT WELD OVERLAY REPAIRTHICKNESS MEASUREMENT LOCATIONS

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4.0 VOLUMETRIC UT INDICATIONS EVALUATION

Figures 4.0-1 and 4.0-2 present the post-weld overlay repair volumetric UT

results for the CK-ES3166 and CK-ES3181 check valve-to-tee weldments.

The Reference 4 calculation package for the check valve overlay designs

used the original pipe wall thicknesses (t) determined by ultrasonic '

thickness measurements associated with the characterization of the

original pipe wall indications shown in Figures 1.0-2 and 1.0-3 at/near the

centerline of the valve-to-tee butt weld where the average cross-sectional

applied stresses are the greatest. These thicknesses are as follows: '

CK-ES3166: t = 0.61 "

CK-ES3181: t = 0.58" '

These pipe wall thicknesses differ from the ultrasonically measured

pre-weld overlay repair original pipe wall thicknesses shown in Table 3.0-1

because, as shown in Figure 3.0-1, these latter thicknesses were

measured near the end of the overlay on the tee.

As discussed in the Reference 4 calculation package, the low applied 4

primary stresses acting on the check valve-to-tee weldments permit a

maximum allowable flaw depth (a)-to-thickness (t) ratio (a/t) for an

assumed 360 long flaw of 0.75 per the source equations used to derive

Table IWB-3641-1 in ASME BPVC Section XI (Reference 10). Accordingly, 1

based upon an assumed flaw depth of 100% of the original pipe wall

thickness, the overlay design thicknesses, t , were determined as follows:o>

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CK-ES3166: t, 0.61" / 3 = 0.20"=

CK-ES3181: t = 0.58" / 3 = 0.19"o

Based upon the average pipe wall plus total overlay thicknesses presented

in Table 3.0-1, the following maximum allowable 360 long flaw depths

would be permitted in each weldment:

CK-ES3166: a ,,. 0.75 * 1.54" = 1.16"=mCK-ES3181: a ,,. 0.75 * 1.64" = 1.23"=m

Therefore, the original pipe wall plus seal layer thicknesses presented in

Table 3.0-1 are easily bounded by these maximum allowable 360 long

flaw depths.

The minimum remaining ligament thicknesses (t, per Figure 4.0-3) required

over all circumferentialindications assumed to have a 360 length and any

axial indications greater than 1.5" in length are as follows:

CK-ES3166: t, 0.25 * 1.54" = 0.38"=

CK-ES3181: t, 0.25 * 1.64" = 0.41 "=

As shown in Figure 4.0-1, all of the CK-ES3166 volumetric UT indications

have remaining ligament thicknesses greater than 0.38", therefore, the as-

built geometry of the CK-ES3166 overlay is acceptable per Code Case

N-504-1 (Reference 3) requirements. However, as shown in i;igure 4.0-2,

CK-ES3181 volumetric UT Indication No's. 4 and 6 have remaining

ligament thicknesses less than 0.41", therefore, the as-built condition of

the CK-ES3181 overlay requires further evaluation.

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Per Paragraph (i) of Code Case N-504-1, indications observed during

preservice examinations shall meet the acceptance standards of Table

IWB-3514-2. All of the indications presented in Figures 4.0-1 and 4.0 2

have " negligible" depths reported from the preservice volumetric UT

examinations. For this evaluation, the indication depths, a,, will be

assumed to be 1/32"(0.0325").

Therefore, referring to Figures 4.0-2 and 4.0-3, CK-ES3181 Indication

No's. 4 and 6 are assumed to have the following flaw depth (a)-to-length

(t) aspect ratios:

Indication No. 4: a,/ t = 0.0325" / 1.00" = 0.033

Indication No. 6: a,/ t = 0.0325" / 12.0" = 0.003

Assuming the maximum allowable 360 long flaw depth (t, = 0.41"),

Indication No's. 4 and 6 would be determined to be surface or subsurface

flaws per ASME BPVC Section XI (Reference 10) Table IWB-3514-2 and

Figure 4.0-3 as follows:

Indication No. 4: d = a /2

= 0.0325" / 2 = 0.016"

Soo = t,4 ,0.40" > 0.4d = 0.006"=

So t, - (Soo + a)=

0.41" - (0.40" + 0.0325")=

= - 0.0225" < 0.4d = 0.006"

/. Indication No. 4 is a surface flaw.

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Indication No. 6: d = a /2

= 0.0325" / 2 = 0.016"

Soo = t,.

= 0.25" > 0.4d = 0.006"

S,o = t, - (S o + a)o= 0.41 " - (0.25" + 0.0325")

= 0.1275" > 0.4d = 0.006"/. Indication No. 6 is a subsurface flaw.

Table 4.0-1 presents allowable volumetric preservice examination planar

flaw depth (a)-to-thickness (t) ratios for a 0.41" nominal wall thickness by

interpolating Table IWB-3514-2 values. Per Table 4.0-1, the aspect ratio

(a,/t = 0.033) for surface Indication No. 4 conservatively permits an alt

ratio of 9.4%. Therefore, Indication No. 4 has an allowable flaw depth of

0.094 * 0.41 " = 0.039 " which is greater than the assumed 1/32" (a i,

= 0.0325") flaw depth. Also, per Table 4.0-1, the aspect ratio (a/t

= 0.003) for subsurface Indication No. 6 conservatively permits an a/t

ratio of 9.3%. Therefore, Indication No. 6 has an allowable flaw depth of,

2 * 0.093 * 0.41" = 0.076" which is greater than the assumed 1/32" (a

= 0.0325") flaw depth. Therefore, all the CK-ES3181 volumetric UT

preservice examination indications meet the acceptance standards of Code

Case N-504-1 Paragraph (g).

._. _

.

; : \,

- 21 - 0054-00101-001-110VECTRA Revision i

-@4

. . . . . . . . . . . . . . . . . . . ........... .................... -- -

3.o= -@4@ @-

A

| 1.5' 4...--g8*~~~~-~~--' ' - - -'. . . . . . ....1.01.. . ._- .-................-....---......

I ,Y Y 2 08 _v v _

A._ i &

__J .__ _ .. ........_ VALVE .. . ...-.. _ {

_ _ . .

1.25' k 1.3'

f ff fi

TEE

I 66.0"| | r .0'l |7.5'l 1**

pieswonwpo) 157.0'i [11,0'j.

^'LENGTH DEPTH COMMENT

O. L GAME T

1.5* Lack of Bond |1 1.4*'"

2 0.2* 0.75" Pinhole |"*

3 0.2* O.75* Pinhole'"

4 8' *" 0.40' Lack of Bond5 0.6* O.55*"*

* Remaining ligament (t,) per Figure 4.0-3.* * Does not correspond to 0" position in Figure 1.0-2.

l*** Negligible depth. ]

Figure 4.0-1

CK-ES3166 CHECK VALVE-TO-TEEPOST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP l

(References 19 and 20) l

- __

: .- ,

- 22 - 0054-00101-001-110VECTRA R evisio n 3

|

'@ \ | 1

l

2.75'

_-.._...-.. ___.-. ___......_. .......s..___. ____ _. ____.-..____.l @ 02F ii_ WOR - y

I A A A- -

}-------- VALVE -- ---- [---- -- l------ I ----------------------------. .--0.75'

j |A =1.3*

// //// ///f~

hTEE

I I I| iI4 i.75' | | 21.0*l [8.5'] @ **

maiwonwo: 146.5'l 46.0*j [gp

' ^'LENGTH DEPTH COMMENTNO. IG ME T

1 6' '" 0.55"

2 4.5* "* 0.50'3 0.10* "* 0.60*

4 1.00* *" 0.40'

5 3.25" "* 1.25'

6 12.0" *** 0.25** Remaining ligament (t,) per Figure 4.0-3.** Does not correspond to 0" position in Figure 1.0-3.*** Negligible depth.

Figure 4.0-2

CK-ES3181 CHECK VALVE-TO-TEJPOST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP

(Reference 21)

.

* r,- .

- 23 - 0054-00101-001-110VECTRARevision i

oUTSIDE DIAMETER (00)

_g INSIDE DtAMETER (10)-

: A s . . . . . ... .. :4A%~

. n[- ' . ; b.[f* kf' "'. ^

: : ,y

- 24 - 0054-00101-001-110yRevision 0

Table 4.0-1

ALLOWABLE VOLUMETRIC PRESERVICE EXAMINATION PLANAR FLAWS

Nominal Wall Thickness (inches)

Aspect 0.312''' O .41 "" 1.0"'Ratio

surface Subsurface Surface Subsurface Surface Subsurface(all)Flaw alt Flaw att Flaw alt Flaw alt Flaw alt Flaw alt

(%) (%) (%) (%) (%) (%)

0.00 9.4 9.4Y 9.3 9.3Y 8.5 8.5Y

0.05 9.6 9.6Y 9.5 9.5Y 8.6 8.6Y

0.10 9.8 9.8Y 9.7 9.7Y 8.8 8.8Y

NOTES:

1. a (surface flaw) = 2d (subsurface flaw) = flaw depth.2. t = flaw length.3. t = nominal wall thickness.4. S = flaw edge-to-surface distance.5. If S < 0.4d, corresponding flaw is considered a surface flaw.

If S .;>_. 0.4d, corresponding flaw is considered a subsurface flaw.6. Y = S/a. If Y > 1.0, use Y = 1.0.7. From Reference 10, Table IWB-3514-2.8. Interpolated from 0.312" and 1.0" values.

: | w.

- 25 - 005 & o0101-001-110VECTRA |Revision 1 '|||

5.0 OVERLAY WELDMENT AND SYSTEM AFFECTS |

|Code Case N-504-1 (Reference 3) Paragraph (g) requires an evaluation of a!

repaired weldment/ component and the repair's affect on other Weldments ||

and components within the repaired weldment/ component's piping system. I

For a repaired weldment/ component, this evaluation shall consider the

affects of waterbacking as it affects residual stress produced by the

overlay in combination with other applied system loads. The evaluation

shall also address increases in piping system loads caused by overlay

stiffness, deadweight, and axial shrinkage affects.

5.1 Weldment Evaluation

The Reference 22 report presents an evaluation of the effectiveness of a

Code Case N-504-1 weld overlay repair relative to proposed root causes

affecting the structural and service integrity of the CK-ES3166 and

CK-ES3181 containment sump suction check valves. After determining

that high or even moderate cyclic load magnitudes do not occur at the

check valve-to-tee weldments, the overlay effectiveness evaluation

document presents the following potential root causes for the indications

discovered in the check valves:

a. Intergranular Corrosion (IGC).

b. Intergranular Stress Corrosion Cracking (IGSCC).

c. Original construction casting or welding flaws.

As discussed in Sections 2.2 and 2.6, the overlays applied to the check

valve-to-tee weldments utilized the following implementation parameters:

|

_ _ _ _ - _ - _ _ _ - - _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _

-.

.'Q

- 2e - 0054 00101 001.,,oVECTRA Revision 0

a. Filler metals having maximum carbon contents of 0.035% and

as-deposited ferrite contents greater than 7.5 FN.

b. Machine GTAW techniques to apply parallel, overlapping,360*

circumferential beads around a weldment with waterbacking,

c. A maximum allowable "interpass" temperature of 212 F.

d. A maximum heat input of 28 Kjoules/ inch for at least the first two

design (structural) layers of an overlay.

The overlay application, waterbacking, and heat input parameters

described above have been shown to produce a typical axial through-wall

residual stress pattern acting to mitigate circumferentially oriented,

stress-driven flaws as shown in Figure 5.1-1 (Reference 23). However, in

order to provide defense-in-depth against corrosion-driven cracking, the

cast-in-place, as-deposited weld overlay filler metal must provide the

ultimate barrier to arrest corrosion- and stress corrosion-driven cracking.

As shown in Figure 5.1-2 (Reference 24), weldments with a maximum

carbon content of 0.035% and a ferrite content of 7.5 FN (7.5%) are

inherently resistant to aggressive failure mechanisms such as IGSCC. The

actual measured first and second layer ferrite contents for the check valve

overlays exceeded 7.5 FN thereby further increasing their anticipated

resistance to corrosion cracking.

The inherent resistance of low carbon /high ferrite content overlays is

particularly important in the presence of through-wall flaws as found in the

CK-ES3166 check valve-to-tee weldment. In these cases, beneficial under-

'.

.. ,< y

- 27 - 0054-00101-001-110VECTRA nevision 0

the overlay residual stress patterns are of little/no help in mitigating stress

corrosion cracking because the overlay has yield level tensile residual

stress through its complete thickness (see Figure 5.1-1). As shown in

Figure 5.1-3 (Reference 25), overlays applied over through-wall flaws

utilizing filler metals meeting the requirements of Code Case N-504-1 have

been shown to resist IGSCC in actual plant service. The buat sample

shown in Figure 5.1-3 was extracted from an overlay that had been in

service for one fuel cycle at Quad Cities Unit 2. During overlay

application, a steam blow-out was encountered requiring excavation and

weld repair. The preservice volumetric UT examination of this overlay

confirmed that the steam blow-out was sealed just below the overlay-to-

original pipe surface interface. Nevertheless, at the next refueling outage,

a follow-up volumetric UT examination suggested that the steam b|ow-out

had grown approximately half way through the overlay thickness.

However, as shown in Figure 5.1-3, the follow-up UT inspection had

incorrectly determined the remaining ligament depth because the steam

blow-out is clearly arrested at the weld repair-to-original pipe surface

interface even after one fuel cycle of operation.

The maximum interpass and heat input parameters utilized also help to

inhibit further sensitization of the original weldment surface, The

Reference 26 pipe replacement study provides recommended welding

parameters for the application of corrosion-resistant cladding (CRC) to

avoid / reduce sensitization of exposed base rnetal. This study suggests a

maximum interpass temperature of 250 F and a maximum heat input of 25

Kjoules/ inch. The maximum 212 F interpass temperature used to apply the

check valve overlays is clearly bounded by the EPRI-recommended value

and a maximum 28 Kjoule/ inch heat input on a waterbacked surface

.. ;.. 7

- 28 - 0054-00101-001-110VECTRA neyision i

is judged to be equivalent to the EPRI-recommended value on a non-

waterbacked surface.

Therefore, the weld overlay repairs applied to the CK-ES3166 and

CK-ES3181 check valve-to-tee weldments conservatively re-establish the

original ASME BPVC structural factors of safety while providing a

corrosion-resistant barrier against unacceptably deep crack propagation for

the balance-of-plant life witnout creating new highly sensitized potential

leakage paths.

5.2 System Evaluation

Rigorous evaluations of sustained stresses resulting from weld overlay

repair axial shrinkage have been performed for nuclear plants around the

world on piping systems with many overlays having axial shrinkages

comparable to those reported in Table 3.0-3. Such evaluations typically

result in weld overlay shrinkage (WOS) stresses, in unrepaired weldments

away from rigid anchors / supports, of under 1,000 psi. WOS stresses have

combined with other piping system stresses to create yield level stress

magnitudes in weldments adjacent to rigid r -hors only in cases involving

short runs of piping with multiple overlays. |

As discussed in NUREG-0313 (Reference 27), the mcgnitude of sustained|

stresses acting on stress-imoroved, austenitic stainless steel, Boiling Water

Reactor (BWR) primary recirculation system piping weldments is important

in determining their expected resistance to IGSCC. However, the Safety

injection, Containment Spray, and Shutdown Cooling piping weldments of

the PNP ESS have not been stress-improved because IGSCC had not been

.- . . -.- - . _ ,_ . - . . . . _

.

;: : ,

- 29 - 0054-00101-001-110VECTRA noyision o

established as a degradation system in the past. Therefore. there is no

current reason for performing a sustained stress evaluation of the ESS.

piping weldments because there are no stress-improved weldments.

If WOS stresses were to be determined in the ESS piping weldments, they <

would be expected to be less (and in most cases, much less) than 1,000

psi. As shown in Figures 5.2-1 and 5.2 2, only one overlay was applied to

each containment sump piping system and each system has both large

vertical and horizontal distances from its associated containment

penetration to the first anchor or support that would be affected by overlay'

axial shrinkage. The configurations of piping shown in Figures 5.2-1 and

5.2-2 result in very flexible systems which easily accommodate small

amounts of overlay axial shrinkage.

, , . - . . _ - . _ _ _ - _ _ - _ _ - _ - _ _ _ -

.

,. ; .' y

- 30 - 0054 00101-001-110VECTRA Revision o

___.. ....m..........

:. e* % \'a v

,--- g/ /me,

3.-* *----

*.y,ss ._ , !_* ;.. ..

, . . ..a e' i. | ~- ,-,.. i

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Inside Surface Axial Residual Stress

we.n muam

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, . *. . ., , . . . . ... . . . ..

2 .. . .*j T** \, M,.*E* \u- -s

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. .. ... *. Ju. .

|. - ... .. 2 .. . . . *.e*...

F.W.B IEat .emunn

Axial Throuch-Wall Residual Stresa

Figure 5.1-1

TYPICAL POST-OVERLAY AXIAL RESIDUAL STRESS CONDITIONS(Reference 23)

_ _ _ . _

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VECTRA- 31 - 0054-00101-001-110

>

Rev..ision 0 !)

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CLOEED SYMSOL - ICSCC|

OPE N $vMSOL NO OGSCC |

M LFFsLLED$v SOL iGSCC - AT LE AST ONE 5 AMPLESTREN C 4 FA URESCROSS HA TCME D SYMSOL MINOR ENvsRONME NT AL eNF LUENCE

0 00 - CF3CF8veELD(D

CF3 F URNACE0 07 - h 5 $ @ CF85EN$1T12ED

I1

0 06 - $ $ ]a1

0 a* - 6 YV 9 0 e2i'C sitiO*FmaaJ

'

$ > 1000*F /4Sn!u

ON - O As s.E LDED Aa . Lis Aa . snt,

7 Sit LLif t MARD5URF ACED

* * 'o >

> > 0 10 02 - U8 o ]ao

O I0O > ;00i - o ;

ii i l I I I I I i i l i l i Ig

O 2 4 e a 10 s2 is is is 20 22 as as 2e 20 1

F E RRITE t%)

I

Figure 5.1-2 |1

CARBON VS. FERRITE CONTENT AFFECTS ON IGSCC RESISTANCE I(Reference 24)

!

1

.

I

|

!

|1

1

. . - _ . .. . . - . . - .- - . . _ _ . . . - .

-

|i

: .'- y.

l::

) 32 - oosooo,o1001 3,oVECTRA Revision o i.

#.1

'd1

,, ..

t-

|. ;- . I<

;1

?gbOfs. [ ,'

.$; gr ,v., .. '-. . . , .

3. .-.r,-..%,

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.

11.25X Maanification'

D :-6; ' t. O' ' ,,, tp ty;y) j|g.,; { ,'

- .. $,

gr % z. ,s.

' , , ,.f,k, .h. ,'

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Figure 5.1-3 i

BOAT SAMPLE METALLOGRAPHS(Reference 25)

|

. . . _ . .. . _ . _ _ . . _ _ _ _ _.. _ . _ __ ,._.._ _ _-

.

,

|

|

.Y |*.' .: *

VECTRA~ ~ 54~ ' '~ ' ' ' '

Revision 0

Iv

A ROCANCHOR

d| n=3'J

15' - 6" CK-ES3166 CHECK VALVE.TO-TEE WELDMENT (TYP.)

_

th I % !

L = 2' i'p...

ELEVATION ," 2,= =

, = 9' -, w ;

= 4' = 46', _

CONTAINMENTPENETRATION (TYP.)

~*_

= {' 7,4. .

N Wu

mas "" ) PLAN VIEWr

Figure 5.2-1 >

CK-ES3166 PIPING SYSTEM LAYOUT !,

(Reference 28)

9

r - -. - , . - - _ _ - - -_

. . _ .

i

* V.* *.

~ 34 - 54- 0101-001-110VECTRARevision 0

I$NsItt$'$TTP> 0 - *< c=Ta>>~r"-

[ELEVATION

,

=67 :,CONTAINWENT #

PENETRATION (TYP.)

ren/' :>4N

a

PLAN VIEW = 20'

r = 3' ,

OOA

,

l

Figure 5.2-2 |

CK-ES3181 PIPING SYSTEM LAYOQT(Reference 29)

|

l

|I

|

,

. _ _ _ . . _ . _ _ _ _ _ _ _ . _ _ _ _ . .

.._ ._. _

1

|| | 3

|'- 35 - 0054-00101-001-110

VECTRA neyision o

6.0 SUMMARY AND CONCLUSIONS

This report presents an evaluation of wald overlay repairs applied to the

containment sump check valve to-tee weldments at the Palisades Nuclear

Plant relative to the requirements of ASME BPVC Case N-5041'

(Reference 3). These weldments are on the downstream side of check

valves CK-ES3166 and CK-ES3181 and contain indications attributed to

either IGC, IGSCC, or original construction casting or welding flaws

(Reference 22).

The as-built check valve-to-tee weld overlay repairs meet the requirements

of Code Case N-504-1 and ASME BPVC Section XI (Reference 10),

Paragraph IWB-3640 for each of the potential degradation mechanisms

identified above. This report also illustrates that pre-overlay volumetric UT

indications confined within the CK ES3166 and CK-ES3181 original pipe

wall thicknesses of 0.70" and 0.73", respectively, must grow to depths

greater than 1.16" and 1.23", respectively, with a corresponding length of

360* to exceed the allowable flaw acceptance criteria of ASME BPVC

Section XI, Paragraph IWB-3640.

The weld overlay repairs applied to the check valve to-tee weldments

conservatively re establish the original ASME BPVC structural factors of

safety whilo providing a corrosion-resistant barrier against unacceptably

deep crack propagation for the balance of-plant life without creating new

highly sensitized potentialleakage paths.

_. _ _ _ _ - _ _ _ .

-

.... .-., .,

;

VECTRA~ *~ 5#~ ' '~ ' ~ ' '

n, i ioni

s

7.0 REFERENCES

1. Consumers Power Company Palisades Nuclear Plant Drawing No.M204, " System Diagram - Safety injection, Containment Spray, &Shutdown Cooling System", Sheet No. A, Revision 5.

2. Sargent & Lundy Document No. CMED-058599, " Check Valve LeakRoot Cause, Engineering Analysis, and Repair / ReplacementOptiors", Revision O.

3. American Society of Mechanical Engineers (ASME) Boiler andPressure Vessel Code (BPVC) Case N-504-1, " Alternative Rules forRepair of Class 1, 2, and 3 Austenitic Stainless Steel Piping -Section XI, Division 1", Approval date: August 9,1993

4. VECTRA Document No. 0054-00101-001-200, " Calculation -Package - Containment Sump Check Valves Weld Overlay RepairDesign - Palisades Nuclear Plant", Revision O.

5. VECTRA Document No. 0054-00101-001-100, "ASME Section XIRepair Program - Weld Overlay Repairs to Austenitic Stainless SteelPiping Weldments and Components - Palisades Nuclear Plant",Revision O.

6. VECTRA Document No. 0054-00101001-101, " Procedure forApplication and Examination of Weld Overlay Repairs to AusteniticStainless Steel Piping Systems - Palisades Nuclear Plant",Revision O.

7. Consumers Power Company Purchase Order No. MM0027247.

I8. Consumers Power Company Nondestructive Testing Services Liquid

Penetrant Examination Report, i xaminer: D. Hecksel, Dated:3/11/94, Sheet No. DLH-1, 2 pages (CK-ES3166).

9. Consumers Power Company Nondestructive Testing Services LiquidPenetrant Examination Report, Examiner: D. Hecksel, Dated:3/12/94, Sheet No. DLH-1, 2 pages (CK-ES3181). ;

10. ASME BPVC Section XI, " Rules for Inservice Inspection of Nuclear-Power Plant Components",1992 Edition with 1992 Addenda.

.

**' *, .,_

t

~ 37 - #54-M101-@1-110VECTRA Revision 0

11. Consumers Power Company Nondestructive Testing Services Liquit.Penetrant Examination Report, Examiner: D. Hecksel, Dated:3/21/94, Sheet No. DLH-1, 3 pages (CK-ES3166).

12. Consumers Power Company Nondestructive Testing Services Liquid .Penetrant Examination Report, Examiner: T. Carpenter, Dated:3/22/94, Sheet No. TBC-01,1 page (CK-ES3181).

13. Consumers Power Company Nondestructive Testing Services LiquidPenetrant Examination Report, Examiner: D. Hecksel, Dated:3/22/94, Sheet No. DLH-1,1 page (CK-ES3181).

.

14. Consumers Power Company Nondestructive Testing ServicesSupplementary Sketch, Examiner: D. Hecksel, Dated: 3/22/94,Sheet No. DLH-1,1 page (CK-ES3181).

15. PCI Energy Services Delta Ferrite Measurement Report, W.O.24410749, Dated: 3/25/94, 2 pages (CK-ES3166). !

16. PCI Energy Services Delta Ferrite Measurement Report, W.O.24410748, Dated: 3/25/94, 2 pages (CK-ES3181).

17. Weld Overlay Data Sheet, W. O. 24410770.2, Dated: 3/24/94,,

1 page (CK-ES3166). '

18. Weld Overlay Data Sheet, W. O. 24410771.0, Dated: 3/24/94, |1 page (CK-ES3181). I

19. Virginia Corporation Ultrasonic Examination Indication Record,Examiner: Y. Merey, Dated: 3/21/94, page 5 of 5, with VirginiaCorporation Ultrasonic Examination Record - Profile / Plotting,Examiner: Y. Merey, Dated: 3/21/94, 2 pages (CK-ES3166).

- 1

20. Virginia Corporation Ultrasonic Examination Indication Record, !Examiner: Y. Merey, Dated: 3/22/94, page 1 of 2, with VirginiaCorporation Ultrasonic Examination Record - Profile / Plotting,

'

Examiner: Y. Merey, Dated: 3/22/94, page 2 of 2 (CK-ES3166).

21. Virginia Corporation Ultrasonic Examination Indication Record,Examiner: Y. Merey, Dated: 3/22/94, page 6 of 6, with Virginia 1Corporation Ultrasonic Examination Record - Profile / Plotting,Examiner: Y. Merey, Dated: 3/22/94, 2 pages (CK-ES3181).

l

!

!

-

Ss Y f

- 38 - 0054 00101-001-110i VECTRA Revision 0

22. Sargent & Lundy Document No. CMED-058617, " Evaluation of theEffectiveness of Code Case N-504-1 Repair for Proposed RootCauses for Containment Sump Suction Check Valves", Revision O.

23. Kulat, S. D., Pitcairn, D. R., and Sobon, L. J., " ExperimentalVerification of Analytically Determined Weld Overlay Residual StressDistributions", Transactions of the 8th International Conference onStructural Mechanics in Reactor Technology (SMiRT), Brussels, iBelgium, August 19-23, 1985, Volume D, pages 231-235.

24. Hughes, N. R., Clarke, W. L., and Delwiche, D. E., "IntergranularStress-Corrosion Cracking Resistance of Austenitic Stainless SteelCastings", Stainless Steel Castings, ASTM STP 756, AmericanSociety of Testing and Materials,1982, pages 26-47.

25. Froehlich, C H., Axtine, J. W., Do, H. O., and Holland, D. G., " FieldVerification of the Effectiveness of the Induction Heating Stressimprovement Process and Weld Overlay Repair Techniques on BWRAustenitic Stainless Steel Recirculation System Piping Weldments",12th Smirt Post Conference Seminar No. 2, Assuring StructuralIntegrity of Steel Reactor Pressure Boundary Components, Session 3- Resolution ofIntegrity issues on Operating Plants, Paris, France,August 23-24, 1993.

26. Electric Power Research Institute (EPRI) Document No. NP-2033-LD,"BWR Large-Diameter Pipe Repair / Replacement Study", Volume 2,Final Report, September 1981.

27. United States Nuclear Regulatory Commission (USNRC) DocumentNo. NUREG-0313, " Technical Report on Material Selection andProcessing Guidelines for BWR Coolant Pressure Boundary Piping",Revision 2, published January 1987.

28. Bechtel Drawing No. 03319. " Stress isometric - Safety injection,Containment Spray, and Shutdown Cooling System", Sheet 4 of 8,Revision 4.

29. Bechtel Drawing No. 03319, " Stress isometric - Safety injection,Containment Spray, and Shutdown Cooling System", Sheet 1 of 8,Revision 4. I