ML20070J800
| ML20070J800 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 07/15/1994 |
| From: | VECTRA TECHNOLOGIES, INC. |
| To: | |
| Shared Package | |
| ML18059B107 | List: |
| References | |
| 0054-00101-001, 0054-00101-001-110, 54-101-1, 54-101-1-110, NUDOCS 9407250324 | |
| Download: ML20070J800 (45) | |
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ATTACHMENT Consumers Power Company Palisades Plant Docket 50-255 WELD OVERLAY REPAIRS OF CONTAINMENT SUMP CHECK VALVES FOLLOW-UP INFORMATION July 15, 1994 i
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9407250324 940715 PDR P
ADOCK 05000255 pop ,
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.; .' v 0054-o01o1-001-11o Revision 1 VECTRA 0054.00101.001.110 FINAL REPORT CONTAINMENT SUMP CHECK VALVES
WELD OVERLAY REPAIR IMPLEMENTATION EVALUATION PALISADES NUCLEAR PLANT Prepared for: ;
Consumers Power Company (
Prepared by:
VECTRA Reviewed by: Issued by:
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Carl H. Froehlich, P.E. Dale L. Jor/s Engineering Manager Project M4 nager Date: 14 ZIy I'IfY '
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REVISION CONTROL SHEET TITLE: Final Report - Containment Sump DOC. FILE NO.: 0054.00101.001.110 Check Valves Weld Overlay Repair IrT.plementation Evaluation -
Palisades Nuclear Plant Carl H. Froehlich / Staff Engineer CMM l
NAME/ TITLE INITIALS James W. Axline / Staff Engineer On File NAME/ TITLE INITIALS James A. Brown / Staff Engineer [-
I NAME/ TITLE INITIALS NAME/ TITLE INITIALS AFFECTED DDC. PREPARED ACCURACY CRITERIA PAGE(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 "
15 1 CA/J7 /4/g4 T/ft/g 7/#9/p Corrected typo.
17 & 18 1 incorporated CPCo comment.
21 - 23 1 l 25 & 28 1 W Corrected typo.
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PAGE 1 OF 1 i
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VECTRA Revision 0 TABLE OF CONTENTS l Enae LIST OF TABLES iv LIST OF FIGURES v ,
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1.0 INTRODUCTION
1 2.0 OVERLAY IMPLEMENTATION REQUIREMENTS 6 ,
l 2.1 ASME Section XI Repair Program 6 1 2.2 Overlay Material and Application Requirements 6 2.3 Original Pipe Surface Liquid Penetrant Examination 7 2.4 Original Pipe Surface Repair / Seal Layer PT Examination 8 2.5 Minimum 2 Layer Thickness 8 l 2.6 Ferrite Content 9 2.7 NDE Access 9 ,
2.8 Overlay Design 9 l 2.9 Repaired Weldment/ Component and System Evaluation 10 l 2.10 Pressure Testing 10 2.11 Preservice Examinations 10 2.12 Piping System Support Examination and Other 11 Applicable Requirements I 2.13 Code Case Documentation 11 3.0 AS-BUILT OVERLAY GEOMETRY 14
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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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l LIST OF TABLES Number M Paae 2.6-1 CK-ES3166 and CK-ES3181 Minimum Ferrite 12 Content 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 24 Planar Flaws l
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j . T y -v- 0054-00101-001-110 Revision 0 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 3 Repair Indication Roll-Out Map 1.0-3 CK-ES3181 Check Valve-to-Tee Pre-Weld Overlay 4 Repair Indication Roll-Out Map 1.0-4 CK-ES3166 and CK-ES3181 Check Valve-to-Tee 5 Pre-Weld Overlay Repair Cross-Section 2.8-1 Weld Overlay Repair Design Dimensions 13 3.0-1 As-Built Weld Overlay Repair Thickness Measurement 10 Locations 4.0-1 CK-ES3166 Check Valve-to-Tee Post-Weld Overlay 21 Repair Indication Roll-Out Map 4.0-2 CK-ES3181 Check Valve-to-Tee Post-Weld Overlay 22 Repair Indication Roll-Out Map 4.0-3 Surface and Subsurface Planar Flaws 23 5.1-1 Typical Post-Overlay Axial Residual Stress Conditions 30 l l
5.1-2 Carbon vs. Ferrite Content Affects on IGSCC Resistance 31 l l
5.1-3 Boat Sample Metallographs 32 l 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.
y 0054-00101-001-110 VECTRA Revision o SAFETY INJECTION REFUELING WATER TANK (1) TO HP & LP SAFETY INJECTION &
CONTAINMENT SPRAY PUMPS V V l
CONTAINMENT SUMP _
1 (1)
(1) 4 __
A :
_L 3181 CONTAINMENT 4 '
f >< ll T- PENETRATIONS
'4, N a' >4 !! -
3166 24' x 24' x 14*
TEE V i (1)
Figure 1.0-1 GENERAL LAYOUT OF CONTAINMENT SUMP CHECK VALVES (Reference 1)
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l 8.7 k WELD REPAIRS
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excL,
_b#7* @__. __ @
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@'/ M VALVE J.W L i@ @) n@ ,, I/ On4 i
_t bh i i i in i l in j Co- lis l (32.75 1 [43.37s1 181.2s-l 175.s-l g
@ l36 l 14s.51 [W.Fj TEE l37.37s1 146.251 l 77.7-l (3166 RAW.WPG) l48.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. l
- 4. Original construction repairs of valve body.
Figure 1.0-2 ,
l CK-ES3166 CHECK VALVE-TO-TEE l PRE-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP (Reference 4)
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0054-00101-001-110 VECTRA Revision o A
J.*K%
v i n A
l (if I45 DE) 2' y VALVE
@i =s .@ @' y ll i t
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0" l6.8751 148.375j 159.51 l68.875 75.751 y l0.751 l7.751 l70.751 TEE (3181 FLAW.WPG)
NOTE: All indications were detected during volumetric UT.
Figure 1.0-3 CK-ES3181 CHECK VALVE-TO-TEE PRE-WFLD OVERLAY REPAIR INDICATION ROLL-OUT MAP (Reference 4) l 1
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VECTRA Revision 0 VALVE * -
. TEE
- f. WELD REGION *C' REGION *B' __
REGION *A' l ! ! l t ,
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s FLOW PEG 40NS WPO)
Figure 1.0-4 CK ES3166 AND CK-ES3181 CHECK VALVE-TO-TEE PRE-WELD OVERLAY REPAIR CROSS SECTION (Reference 4)
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0054-00101-001-110 i VECTRA Revision o 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 the s
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 o application and examination procedure was used to control the 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 j overlays 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 the 1
weld overlay repair design thickness.
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'$ k. Y 0054-00101-001-110 VECTRA Revision o i 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 l
l 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 layer i'
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 geometry I
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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VECTRA Revision O 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.
P 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.
y 0054-00101-001-110
. VECTRA Revision 0 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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- . y 0055 00101 001 110 VECTRA Revision o Table 2.6-1 CK-ES3166 AND CK-ES3181 MINIMUM FERRITE CONTENT MEASUREMENTS (References 15 and 16)
CK ES3166 CK-ES3181 First Valve Side 12.5 FN 12.5 FN Design Layer Tee Side 12.5 FN 10 FN Second Valve Side 12.5 FN 12.5 FN l Design Layer Tee Side 12.5 FN 12.5 FN l
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. 0054-00101-001-110 Revision 0 i WELD A ==
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(tyP-)
t-
=f S
-K - ------- - _____ 7,
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. (V T.WPG)
WELD OVERLAY REPAIR DIMENSIONS VALVE 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.
i Figure 2.8-1 l WELD OVERLAY REPAIR DESIGN DIMENSIONS (Reference 4) i e
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l 0054-00101-001-110 Revision 0 l
1 3.0 AS-BUILT OVERLAY GEOMETRY l l
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: ;
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- a. The original pipe wall, seal layer, design (structural) weld overlay i
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). ,
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- c. The first and second design (structural) layer ferrite content i measurements (Table 2.6-1),
- d. The weld overlay axial shrinkage (Table 3.0-3). I l
The thicknesses shown in Table 3.0-1 were measured as shown in Figure 3.0-1. l l
i 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). l l
,- .' y 0054-00101-001-110 VECTRA Revision 3 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)
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 Overlay Width ' _.
- Dimensions A + B in Figure 2.8-1.
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0054-00101-001-110 VECTRA Revision o Table 3.0-3 AS-BUILT WELD OVERLAY REPAIR AXIAL SHRINKAGES (References 17 and 18)
AVG. WITNESS MARK-TO-CK-ES3166 CK-ES3181 WITNESS 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) _
( WELD SEAL LAYER THICKNESS
_ MEASUREMENTS h = 2.25' _,
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L x
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l -= r ,=
j l
NN ' BOUNDARY MARKS (
WTTNESS MARKS (
twow.m1 m Figure 3.0-1 AS-BUILT WELD OVERLAY REPAIR THICKNESS MEASUREMENT LOCATIONS
l . y 0054-00101-001-110 VECTRA seyision i 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, to , were determined as follows:
1 1 .
0054-00101-001-110 VECTRA sevision ,
CK-ES3166: t, = 0.61" / 3 = 0.20" CK-ES3181: to = 0.58" / 3 = 0.19" 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: am,,. = 0.75
- 1.54" = 1.16" CK-ES3181: am,,. = 0.75
- 1.64" = 1.23" 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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VECTRA Revision 0 '
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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0054 00101-001-110 i VECTRA sevision o )
l Indication No. 6: d = a /2
= 0.0325" / 2 = 0.016" Soo
= t,.
= 0.25" > 0.4d = 0.006" S,o = t, - (Soo + a)
= 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).
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0054-00101-001-110 VECTRA Revision i 4 -@
3.o= 4 -@
A l 1.5' 4
. . . . . . ....1.01.. . ._- .-................-....---......
...--g8*~~~~-~~--' ' - - -'
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A &
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__ _ .. ........_ VALVE .. . ...-.. _ {
1.25' k 1.3' f ff i
f TEE I 66.0"l l r .0'l l7.5'l 1 pieswonwpo) 157.0'i [11,0'j LENGTH DEPTH
^' COMMENT O. L GAME T 1.4* '"
1 1.5* Lack of Bond l
2 0.2* 0.75" Pinhole l 3 0.2* O.75* Pinhole 4 8' 0.40' Lack of Bond 5 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-TEE POST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP l (References 19 and 20) l
0054-00101-001-110 VECTRA R evisio n 3 l
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2.75'
_-.._...-.. ___.-. ___......_. .......s..___. ____ _. ____.-..____.
l y @ 02F i i_ WOR I A A A
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VALVE -- ---- [---- -- l------ I ----------------------------. .--0.75' A
=1.3* j l
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// //// ///f h
TEE I I Il i I4 i.75' l l 21.0*l [8.5'] @ **
maiwonwo: 146.5'l 46.0*j [gp LENGTH DEPTH
^' COMMENT NO. IG ME T 1 6' 0.55" 4.5* "*
2 0.50' 3 0.10* 0.60*
4 *"
1.00* 0.40' 3.25" "*
5 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-TEJ POST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP (Reference 21)
,- . r 0054-00101-001-110 VECTRA Revision i oUTSIDE DIAMETER (00)
_g INSIDE DtAMETER (10)-
~
- As. . . . . ... ..
- 4A%
n DESIGN
[- ' . ;
? '
b.[f* *
^<
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d: l U)! a w b;4 <~~
3 y THICKNESS SEAL :
s .-
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- LAYER fN b...Or i
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( THICKNESS . i S, p , ,
} -
Y ORIGINAL OR PIPE WALL 9 ACTUAL THICKNESS [ RAW DEf3TH k I #/ V For indication to be For indication to be I a surface flaw: a subsurface flaw:
So < 0.4d So 10.4d or and Soo < 0.4d Soo 10.4d I where: 2d = a If indication is a surface flaw: a = 2d + (Se or Soo)
Figure 4.0-3 flURFACE AND_ SUBSURFACE PLANAR FLAWS
y ,
y 0054-00101-001-110 Revision 0 Table 4.0-1 ALLOWABLE VOLUMETRIC PRESERVICE EXAMINATION PLANAR FLAWS Nominal Wall Thickness (inches)
Aspect 0.312 O .41 "" 1.0"'
Ratio (all) surface Subsurface Surface Subsurface Surface Subsurface 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.
l w 005 & o0101-001-110 VECTRA Revision 1 l
l l
l 5.0 OVERLAY WELDMENT AND SYSTEM AFFECTS l l
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 l l
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:
l
Q
- 2e - 0054 00101 001.,,o VECTRA 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 0054-00101-001-110 VECTRA 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 blow-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 0054-00101-001-110 VECTRA 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. l As discussed in NUREG-0313 (Reference 27), the mcgnitude of sustained l
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
0054-00101-001-110 VECTRA 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 0054 00101-001-110 VECTRA Revision o
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0054-00101-001-110 VECTRA Rev..ision 0
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OPE N $vMSOL NO OGSCC l STREN C 4 FA URES M LFFsLLED$v SOL iGSCC - AT LE AST ONE 5 AMPLE CROSS HA TCME D SYMSOL MINOR ENvsRONME NT AL eNF LUENCE 0 00 -
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CARBON VS. FERRITE CONTENT AFFECTS ON IGSCC RESISTANCE I (Reference 24) 1 I
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~ ~
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VECTRA Revision 0 I
v A ROCANCHOR dl n
=3'J 15' - 6" CK-ES3166 CHECK VALVE.
TO-TEE WELDMENT (TYP.)
t h I % !
L = 2' p...
i'
" 2, ELEVATION ,
, = 9' -
= 4' _
= 46' w ;
CONTAINMENT PENETRATION (TYP.)
~
= {' 7,4. .
N W u
mas "" ) PLAN VIEW r
Figure 5.2-1 >
CK-ES3166 PIPING SYSTEM LAYOUT !
(Reference 28) 9
i V
~ 34 - 54- 0101-001-110 VECTRA Revision 0 I$NsItt$'$TTP> 0 - *< c=Ta>>~r
[
ELEVATION
, =67 :
CONTAINWENT #
PENETRATION (TYP.)
ren
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- >4N a PLAN VIEW = 20' r = 3' ,
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Figure 5.2-2 l CK-ES3181 PIPING SYSTEM LAYOQT (Reference 29) l l
l I
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l l 3 l
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.
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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 Leak Root Cause, Engineering Analysis, and Repair / Replacement Optiors", Revision O.
- 3. American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Case N-504-1, " Alternative Rules for Repair 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 Repair Design - Palisades Nuclear Plant", Revision O.
- 5. VECTRA Document No. 0054-00101-001-100, "ASME Section XI Repair Program - Weld Overlay Repairs to Austenitic Stainless Steel Piping Weldments and Components - Palisades Nuclear Plant",
Revision O.
- 6. VECTRA Document No. 0054-00101001-101, " Procedure for Application and Examination of Weld Overlay Repairs to Austenitic Stainless Steel Piping Systems - Palisades Nuclear Plant",
Revision O.
- 7. Consumers Power Company Purchase Order No. MM0027247.
I
- 8. 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 Liquid Penetrant 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-@1-110 VECTRA 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 Liquid Penetrant Examination Report, Examiner: D. Hecksel, Dated:
3/22/94, Sheet No. DLH-1,1 page (CK-ES3181).
- 14. Consumers Power Company Nondestructive Testing Services Supplementary 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, l 1 page (CK-ES3181). I
- 19. Virginia Corporation Ultrasonic Examination Indication Record, Examiner: Y. Merey, Dated: 3/21/94, page 5 of 5, with Virginia Corporation 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 Virginia Corporation 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 1 Corporation Ultrasonic Examination Record - Profile / Plotting, Examiner: Y. Merey, Dated: 3/22/94, 2 pages (CK-ES3181).
l
Ss Y f 0054 00101-001-110 i VECTRA Revision 0
- 22. Sargent & Lundy Document No. CMED-058617, " Evaluation of the Effectiveness of Code Case N-504-1 Repair for Proposed Root Causes for Containment Sump Suction Check Valves", Revision O.
- 23. Kulat, S. D., Pitcairn, D. R., and Sobon, L. J., " Experimental Verification of Analytically Determined Weld Overlay Residual Stress Distributions", Transactions of the 8th International Conference on Structural Mechanics in Reactor Technology (SMiRT), Brussels, i Belgium, August 19-23, 1985, Volume D, pages 231-235.
- 24. Hughes, N. R., Clarke, W. L., and Delwiche, D. E., "Intergranular Stress-Corrosion Cracking Resistance of Austenitic Stainless Steel Castings", Stainless Steel Castings, ASTM STP 756, American Society of Testing and Materials,1982, pages 26-47.
- 25. Froehlich, C H., Axtine, J. W., Do, H. O., and Holland, D. G., " Field Verification of the Effectiveness of the Induction Heating Stress improvement Process and Weld Overlay Repair Techniques on BWR Austenitic Stainless Steel Recirculation System Piping Weldments",
12th Smirt Post Conference Seminar No. 2, Assuring Structural Integrity 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) Document No. NUREG-0313, " Technical Report on Material Selection and Processing 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