ML18059B106

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Responds to Requesting Approval for Use of ASME Code Case N-504-1 for Weld Overlay Repair of Containment Sump Check Valves & Forwards Evaluation
ML18059B106
Person / Time
Site: Palisades Entergy icon.png
Issue date: 07/15/1994
From: Rogers D
CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML18059B107 List:
References
TAC-M88874, NUDOCS 9407250320
Download: ML18059B106 (46)
v • d • e


Text

.*..

consumers Power POWERING lllllCHIGAN"S PROGRESS Palisades Nuclear Plant:

27780 Blue Star Memorial Highway, Covert, Ml 49043 July 15, 1994 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 David W. Rogers Plant Safety and Licensing Director DOCKET 50-255 - LICENSE DPR PALISADES PLANT - WELD OVERLAY REPAIRS OF CONTAINMENT SUMP CHECK VALVES - FOLLOW-UP INFORMATION - TAC No. M88874 This letter responds to a request for information by the NRC and contains one new commitment.

By letter dated March 6, 1994, Consumers Power Company (CPCo) reported a leak i~ a 24-inch austenitic stainless steel containment sump check valve and requested approval for the use of ASME Code Case N-504-1 for weld overlay repair of the subject valve and the corresponding valve in the alternate train.

In a letter dated April 6, 1994, the NRC concluded that the repair of the valve using ASME Code Case N-504-1 would provide an acceptable level of quality and safety and authorized CPCo to use the Code Case method of repair.

The April 6, 1994 NRC letter also requested that within 30 days of completing the forced outage CPCo document the following information for the containment sump check valves weld repairs: 1) the as-deposited ferrite content; 2) the as-built overlay thickness; 3) an analysis of the shrinkage stresses done in accordance with the criteria of ASME Code Case N-504-1 for the weld repairs; and 4) a written commitment to inspect these valves every refueling outage using ultrasonic techniques demonstrated to be effective.

The -Pali sades -Plant returned on.->fi ne following the fo~ced outage on.June 18, 1994.

The attached-report by VECTRA entitled,. "Containment Sump Check Valves Weld Overlay Repai.r Implementation Evaluation," provides an evaluation of the implemented weld overlay repair. The report contains the information

' \\

(~~-9-4-07_2_5_0_3_2_0~9-4-07~15~~~--).

PDR ADOCK 05000255 I

P PDR A CMS' ENERGY COMPANY

2 requested in Items 1, 2, and 3 above as follows:

1) the as deposited minimum ferrite content of the weld overlay repair was determined to be 10 FN (ferrite number) for both valves as is stated in Section 2.6, Table 2.6-1 of the attached report; 2) the average design overlay thickness for the check valves was 0.75~inches for CK-ES3166 and 0.84-inches for CK-ES3181 as stated in Section 3.0, Table 3.0-1 of the attached report; and 3) an analysis of shrinkage stresses for the weld repairs is contained in Section 5.0 of the attached report.

In response to Item 4 above, the Palisades 40-year Master Jnservice Inspection Plan has been revised to require surface and volumetri~ examinations for both of th~ containment sump check valves on a refueling outage frequency.

This is a new commitment.

~UJ.~

David W Rogers Plant Safety and Litensing Director Ct:Administr~tor.Regton Ill, USNRC Resident Inspector, Palisades Attachment

ATTACHMENT

.Consumers Power Company Palisades Plant Docket 50-255 WELD OVERLAY REPAIRS OF CONTAINMENT SUMP CHECK VALVES FOLLOW-UP. INFORMATION 9407250324 940715 PDR ADOCK 05000255 p

PDR July 15, 1994

VECTRA

  • Reviewed. by:

FINAL REPORT 0054-00101-001-110 Revision 1 0054.00101.001.110

Con*sumers Power Company Prepared by:

VECTRA Issued by:

Carl H. Froehlich, P.E.

Engineering Manager Project Date:

ii/ :£1'1 119'/

'EVISION CONTROL AET.

TITLE:

Final Report - Containment Sump DOC. FILE NO.:

0054.00101.001.110 AFFECTED PAGE!SI iii - v 1 - 38 15 17 & 18 21 - 23 25 & 28

. Check Valves Weld Overlay Repair Implementation Evaluation -

Palisades Nuclear Plant Carl H. Froehlich I Staff Engineer NAME/TITLE James W. A.xline I Staff Engineer NAME/TITLE Janies A. Brown I Staff Engineer NAME/TITLE NAME/TITLE DOC.

. PREPARED

. ACCURACY CRITERIA REV *.

BY/DATE CHECK BY/DATE CHECK BY/DATE 0

On File On File On File 0

~~A-tiff tfr. y,.,/,4 1

Cal~ ?/13/gf.

1

) *.*

)

1 1

- ii -

INITIALS On File INITIALS e

t.JWITIALS INITIALS

_1 REMARKS Issued for use.

Corrected typo.

Incorporated CPCo comment.

Corrected typo.

PAGE OF

.i

I

'I

.VECTRA

- iii -

0054-00101-001-110 Revision 0 TABLE OF CONTENTS Page LIST OF TABLES iv LIST OF FIGURES *

v.

1.0 INTRODUCTION

1 2.0 OVERLAY IMPLEMENTATION REQUIREMENTS 6

2.1.. ASME Section XI _R'epair Program 6

2.2 Ov~rlay 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 2.6 Ferrite Content 9

2.7 NOE Access 9

2.~

Overlay Design

9.

2.9 Repaired. Weldment/Component and System Evaluation 10 2.lO Pressure Testing

  • 10 2.11 Preservice Examinations 10 2.12 Piping System Support Examination and Other 11 Applicablei Requirements 2.13 Code Case Documentation 11 3.0 AS-BUil T OVERLAY GEOMETRY 14 4.0 VOLUMETRIC UT INDICATIONS EVALUATION 17 5.0 OVERlA Y WELDMENT AND SYSTEM AFFECTS.*

25 5.1 Weldment EvalLJation 25

. 5.2 System Evaluation 28 6.0 -

SUMMARY

AND CONCLUSIONS 35 1.0*

REFERENCES 36

'I V VECTRA

- iv -

0054-00101-001-110.

Revision 0 LIST OF TABLES Number Title Page 2.6-1 CK-ES3166 and CK-ES31.81 Minimum Ferrite 12 Content Measurements t

' 3.0-1 As-Built Weld Overlay Repair Thicknesses 15 3.0-2 As-Built Weld Overlay Repair Widths 15 3.0-3

16.

4.0-1 *.'

  • .Allowable Volumetric Preservice Examination 24 Planar Flaws

VE CT RA Number 1.0-1 1.0-2 1.0-3 '

,.0-4 2.8-1 3.0-1 4.0-1 4.0-2 4.0-3 5.1-1 5..1-.2 -

5.1-3 5.2-1.

5.2-2

- v -

0054-00101-001-110 Revision 0 LIST OF FIGURES Title Page General Layout of Containment Sump Check Valves

2.

CK-ES3166 Check Valve-to-Tee Pre-Weld Overlay 3

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

Repair Indication Roll-Out Map CK-ES3166 and CK-ES3181 Check Valve-to-Tee 5

Pre-Weld Overlay Repair-Cross-Section Weld Overlay Repair Design Dimensions 13 As-Built Weld Overlay Repair Thickness Measurement 16 Locations CK-ES3166 Check Valve-to~Tee Post-Weld Overlay

. 21 Repair Indication Ro11..:out Map CK-ES3181 Check Valve-to-Tee Post-Weld Overlay-

. 22 Repair Indication Roll-Out Map Surf~ce and Subsurface Planar Flaws

23.

Typical Post-Overlay Axial Residual Stress Conditions 30 Carbon vs. Ferrite Conte_nt Aftects-on IGSCC R_esi$fan.ce 31 Boat Sample Metallographs 32 CK-ES3166 Piping System Layout 33 CK-ES3181 Piping System Layout 34

'V VECTRA 0054-00101-001-110 Revision 0 1.. 0 INTRODUCTION A leak leading to the shutdown of Consume*r Power Company's (CPCo)

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 n_ondestructive e~aminations 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 general location 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 whi.ch are each welded to a 24" x 24" x 14" tt;!e 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 Ma.rch, a weld overlay repair meeting the requirements of American Society of Mechanical

.Engineers (~SME) Boiler and Press*ure Vessel Code (BPVC) Case N-504-1 (Reference J) was selected as the repair ~lternativ~.

"- This report presents an evaluation of. the implemented_ weld. overlay r~pairs..

  • VECTRA *

.SAFETY INJECTION REFUELING WATER TANK 0054-00101-001-110 Revision 0

'(1) TO HP & LP SAFETY INJECTION &

VECTRA 0054~00101-001-110 Revision 0

@-]~

2*

REQION"A" (1.5"* 1.7"WIDE}

~

132~75"1 ~

~ 145.5"1 137.3754 146.25"1 2.2*

I 61 ~25"1

~

I ln.5"1 ln.rl (3166FLAW.WPG) 148.5"1 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

~adiographic examinc1tion..

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)

WELD

. REPAIRS

. (4).

i TEE

VECTRA 0054-00101-001-110 Revision 0

    • REGION 'A' (0.9"
  • 1.5" WIDE)

REGJON'B'.

(1,.2' *. 1.45' WIDE)

CD -

I I VALVE

~~~~~~~~~~~~~.,.,..,..,..,.,....,..,. t (31811=:LAW.WPG) ls~.s*I

~l1s.

1 1s4

'170.754 NOTE:

All indication_~ w~re detected during volumetric UT.

Figure 1.0-3 CK-ES3181 CHECK VALVE-TO-TEE PRE-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP (Reference.4) i TEE

/

'. V

.VECTRA. VALVE 4 t

"'TEE

. l WELD REGION *e* 14

1. 1*

REGION "A".

i I 1

  • I REGION *c*

I FLOW 0054-00101-001-110 Revision 0 (REGIONS.WPO)

Figure 1.0-4 CK-ES3166 AND CK-ES3181 CHECK VALVE-TO-TEE PRE-WELD OVERLAY REPAIR CROSS-SECTION.

(Reference 4) - *.

'V
e.

VECTRA 0054-00101-001-110 Revision 0 2.0 OVERLAY IMPLEMENTATION REQUIREMENTS The weld overlay 'repairs applied t.o the CK-ES3166 and CK-ES3181 ch*eck

  • valve-to-te.e weldments were implemented in accordance with the
  • Accordingly, the Reference 5 Repair Program was prepared to detail currently applicable and original construction codes; flaw removal methods;.*

general weld overlay repair application, design, implementation documentation, and permanent record requirements; nondestructive examination (NOE) and system press.ure testing requirements; and form*

NIS-2 documentation requirements.

2.2 Overlay Material and Application Requirements*

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

' _ metal bave a ma><;imum c_arbon con_te_nt 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 us~d to control the implementation of weld overlay repairs on the CK-ES31 66 and CK-ES3181 check valve-to-tee weldments.

. V VECTRA 0054-00101-001-110 Revision 0 As required by the Reference 7 purchase order, all filler metals used during machine Gas Tungsten Arc Welding (GTAW) for the application of the 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 w~lders, welding op.erators, and welding procedure. specifications.

c.

Overlay application l,(Vith 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 Original Pipe Surface Liquid Penetrant Examination Code Case N-504-1 Paragraph {c) requires that the original pipe surface be

-- ---- -e~amined by the liquld 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 weld overlay repair design thickness:

,(

VECTRA.

- 8 ~

0054-00101-001-110 Revision O 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 pipe 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 seal layer 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) thickn.esses.

2.4 Original Pipe Surface Repair/Seal Layer PT Examination Code Case N-504-1 Paragraph (d) reqt..Jires that any excavation repairs or I

seal layers applied over the. original pipe surface also be examined by the PT examination technique with a maximum indication acceptance criteria.

of 1 /1 6. The seal layers applied to.the CK:.ES3166 and CK-ES31_81

  • weldme~ts were* PT examined and found acceptable per a zero toleran~e

.size acceptance criteria required by the Reference 6 application and examination procedure (References 8 and 9).

2.5

  • Minimum 2 Layer Thickness*

Code Case N-504-1 Paragraph (el 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 for the CK-ES3166 and CK-ES3181 weldments.

VECTRA 0054-00101-001-110 Revision 0 2.6 Ferrite Content Code Case N-504-1 Paragraph (e) also requires that the first layer considered to be part of the design (structural) weld overlay r.epair

'. thickness sha.11 have a minimum.ferrite content of 7. 5 FN yvithout: requiring further evaluation. As shown in Table 2.6-1, all ferrite content measurements for the first two design (structural) layers of the CK-ES3 i 66 and CK-ES3181 overlays exceeded 7.5 FN.

2. 7 NOE Access Code Case N-504-1 Paragraph (f) requires that an overlay's geomefry provide access for PT and volumetric ultrasoni.G (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 NOE results reported through-out this evaluation report.

2.8

. Overlay Design The Reference 4 calculation package presents the design of the* weld overlay repairs for the CK-ES3166 and CK-ES3181 check valve-to-tee

~-weldm~nts: The *over.lays were designed in accordaf')ce with Paragraph (f) of ASME BPVC Case N-504-1 (Reference 3) *and Paragraph IWB-3640 of

~

ASME BPVC Section *x1(Reference10). Figure 2.8-1 presents.the design weld overlay repair georfletries.

. ' " V VE CT RA 0054-00101-001-110 Revision 0 2.9. Repaired Weldment/Component 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/componer\\t's piping system.

  • For the CK-ES3166 and CK-ES3181 check valve-to-tee weld overlay repairs, an evaluation of these concerns is presented in Section 5.0.

2.10 Pressure Testing 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 requir.ed by the Reference 5 Repair Progra~, the*

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

. was hydrostatically test~d. In addition, even. th~ugh it was applied over indications that did not penetrate the pressure boundary, the CK-ES3181 I

overlay was also hydrostatically tested.

2.11 Preservice Examinations Code Case N-504:.1 Paragraphs (i) and (j) require that a completed overlay

~e 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 plated 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.
  • vECTRA. 0054-00101-001-110 Revision 0..

2.12

  • Piping System Support Examination and Other Applicable Requirements Code Case N-504-1 Paragraph (k) requires a VT-3 examination of piping system restraints, suppqrts, 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 (I) states that the requiremen~s 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 (ni) requires weld overlay repairs applied !n 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..

VE CT RA

.. 0054-00101-001-110.

Table 2.6-1

. CK-ES3166 AND CK-ES3181 MINIMUM FERRITE CONTENT MEASUREMENTS (References 15 and 16)

I I

CK-ES3166

  • CK-ES3181 First Valve Side 12.5 FN 12.5 FN Design Tee Side 12.5 FN 10 FN Layer Revision 0 I

.,Second Valve Side 12.5 FN 12.5 FN Design Laver Tee Side 12.5 FN 12.5 FN

.. -- *-* -*~-:..

-*~

--~-

VECTRA 0054-00101-001-110.

Revision 0 it., WELD A

I B

(V-T.WPG)

VALVE WELD OVERLAY REPAIR DIMENS.IONS NO.

t 0

{ 1)

A B

CK-ES3166 0.20" 4.6" 2.0" CK-ES3181 0.19" 4.4" 2.0" NOTES:

( l) t 0 = minimum design thickness.

(2)

Final contour based upon volumetric UT examioation requirements.

  • _*. Figure 2.8-1 WELD OVERLAY REPAIR DESIGN -DIMENSIONS (Reference 4)

VE CT RA-3.0 AS-BUil T OVERLAY GEOMETRY 0054-00101-001-110 Revision 0 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:

a.

_ The original pipe wall, seal layer, design (structural) weld overlay 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).

  • c.

The first and second design (structural) layer ferrite content_

m~asurements (Tc:ible 2.6~1 ).

- d.

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

- The thicknesses shown in Table 3.0-1 were measlJred as shown in Figure 3.0-1.

A comparison of the design (structural) overlay thicknesses presented in 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 co6servatively 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).

VECTRA

. t

- 1 5 -

0054-00101-001-110 Revision 1

  • Table 3.0~ 1 AS-BUILT WELD OVERLAY REPAIR THICKNESSES (References 17 and 18) l-cK-ES3166 I CK-ES3181 Avg. Original Pipe Wall*

0.70" 0.73" Thickness (A)

Avg. Pipe Wall + Seal 0.79"

. 0.80" Layer Thickness (8).

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

Avg. Pipe Wall + Total 1.54" l.64" Overlay Thickness (D)

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

Avg. Design (Structural) 0.75."

0.84" Overlay Thickness (F = D - 8)

  • Table 3.0-2 AS-BUILT WELD OVERLAY REPAIR WIDTHS (References 17 and 18)

I CK-ES3166 I CK-ES3181 I

I Avg. Shoulder-to-6.7"

-,*6.6';

Shoulder Overlay Width*

  • Dimensions A + 8 in Figure 2.8-1.

I I

I I

VECTRA -

- 16.-

0054-00101-001-110

.

  • Revision o.

Table 3.0-3 AS-BUil T WELD OVERLAY REPAIR AXIAL SHRINKAGES (References 17 and 18)

AVG. WITNESS MARK-TO.,

WITNESS MAR.K DISTANCE Before Overlay (A)

After Overlay (8)

Avg. Qverlay Shrinkage (C =.B - A)

SEALLAYER I

CK-ES316.6 9.55" 9.33" I

0.22" t WELD I

I CK-ES3181 9.38" 9.05."

I 0.33".

BOUNDARY MARKS t.

I I

WITNESS MARKS t (WOR'TliK1.WPG)

Figure 3.0-1 AS-BUil T WELD OVERLAY REPAIR THICKNESS MEASUREMENT LOCATIONS

v '\\/

VECTRA

.. -.17 -

4.0 VOLUMETRIC UT INDICATIONS EVALUATION

. 0054-00101-001-110 Revision 1

  • Figures 4.0-1 and 4.0-2 pres.ent the post-weld overlay repair volumetric UT results for the CK-ES3166 and CK-ES3181 _check valve-to-tee weldmerits.

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 ~'here the average cross-sectional

'applied.stresses are the greatest. These thicknesses are as foll~ws:

c*K:.ES31 66:

CK-ES3181:

t t

= 0.61"

= 0.58" These pip_e wall thicknesses differ from the ultrasonically measured pre..:weld overiay 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 disc.us~ed ir:t the_ Reference 4 calculation package, the low applied primary stresses acting on the check valve-to-tee weldmerits 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, based upon an assumed.flaw depth of 100% of the original pipe wall

  • thickness, the overlay design thicknesses, t 0, were determined as follows:

VE CT RA CK-ES3166:

CK-ES3181:

= 0.61" I 3

=0.58"/3 0054-00101-001-110 Revision 1

= 0.20"

= 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 iri each weldment:

CK-ES3166:

amax.

=0.75*1.54"

=1.16" CK-ES3l81:

amax.

= 0. 75

  • 1.64"

= 1.23" Therefore, the.origiri_al pipe wall plus seal layer thicknesses presented in Table 3.0-l are easily bounded by these maximum allowable 360° long flaw depths.

The minimum remaining 'ligament thicknesses (tr per Figure 4.0-3) required over all circumferential indications assumed to h'ave a 360° length ~nd any; axial indications greater than 1. 5" in length are as follow,s:

CK-ES3166:

CK-1;53181:

= o'.25

  • 1.54'.'

= 0.38"

= 0.25

  • 1.64" ' = 0.41" As shown in Figure _4.0-1, all of the CK-ES3166 volumetric UT indications

. hav_e*r*~m_aini.ng !igament 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 i~ Figure 4.0-2, CK-ES318l volumetric UT Indication No's. 4 and 6 have remaining ligament thicknesses less tha*n 0.4'.l 1 ", therefore, the as-built condition of the CK-ES3181 overlay requires further.evaluation..

VECTRA 0054-00101-001-110 Revision 0 Per Paragraph (i) of Code Case N-504-1, indiccitions 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

~xaminations. For this evaluation,. the indication depths, ai, will be assumed to be 1 /32" (0.0325").

Therefor~, referring to Figures 4'.0-2 and 4.0-3, CK-ES3181 Indication

. No's. 4 and 6 ate assumed to have the foliowing flaw depth (a)-to~l.ength

( £) aspect ratios:

Indication No. 4:

Indication No. 6:

a/£.

  • = 0.0325" / '1.00" a/£

=. 0.0325" I 12.0".

= 0.033

'= 0.003 Assuming the maximum allowable 360~ long flaw depth (tr =_ 0.41 "),

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

. flaws per ASME BPVC Section XI (Referenc;e 10) Table IWB-3514-2' and Figure 4.0-3 as follows:*

Indication No. 4:

d

= a 12

= 0.0325" I 2== 0.016"

,= 0.40" > 0.4d = 0.006" S10

= tr - (Sao +' a)*

= 0.41" - (0.40" + 0.0325")

= - 0.0225" < 0.4d = 0.006"

. Indication No.. 4 is a surface flaw.

'\\/

VECTRA 0054-00101-001-110

      • Revision 0 Indication No. 6:

d

= a 12

= 0.0325" r 2 = 0.016"

= 0.25" > 0.4d = 0.006" SID

= tr - ( 500 + a)

= 0.41" - (0.25." + 0.0325")

= 0.1275" > 0.4d = 0.006"

.*. Indication No. 6 is a subsurface flaw.

Tab'e 4.0-1 pres~nts allowable volumetric preservic;:e examination planar flaw depth (al-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/£ = 0.03J) for surface Indication No. 4 conservatively perm.its an alt***.

ratio of 9.4%. Therefore, Indication No. 4 has an allowable flaw depth of 0.094

  • 0.41" = 0.03~" which is greater than the assumed 1132" (.a;

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

=* 0.003) for subsurface Indication No. 6 conservatively permits an alt rati.o*of 9.3%. Therefore,*lndication No. 6 has an allowable flaw depth of

. 2

  • 0.093
  • 0.41" = 0.076" which is greater than the assumed 1132" (a;

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

  • preservice examination indications meet the acc(3ptance standards of Code

~

~

Case N-504-1 Paragraph (g).

. -;,. *vECTRA 0054-00101-001-110 Revision 1

~. =.._..

~----- ---------- --------------------------------------------------------------------

(3188WOR.WPG)..

IND.

NO.

1 2

3 4

5 TEE LENGTH DEPTH REMAINING COMMENT LIGAMENT*.

1.4.*

1.s*

Lack of Bond 0.2*

o.1s**

Pinhole o.r o.1s*

Pinhole a*

0.40*

Lack of Bond o.s*

o.ss*

Remaining ligament (t,) per Figure 4.0-3.

Does not correspond to O" position in Figure 1.0-2.

Negligible depth..

Figure 4.0-1 CK-ES3166 CHECK VALVE-TO-TEE

. POST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP (References 19 and 20)

l

.,.. V VE CT RA 0054-00101-001-110 Revision 1

=i '

---~---~~----------------------~------- ------

~----!~-------------

TEE (3111WOR.WPO)

IND.

NO.

1 2 '

3 4

.5

~

LENGTH 5*

4.5*

0.10*

1.00*

3,25*

12.0**

2.75" II~

~~

DEPTH REMAINING LIGAMENT*

.0,55*

0.50*

o.so*

0.40*

1.25*

0.25*

COMMENT Remaining ligament (t,) per Figure 4.0-3.*

Does not correspond to O" position in Figure 1.0-3.

Negligible depth.

Figure 4.0-2 CK-ES3181 CHECK VALVE-TO-TEE POST-WELD OVERLAY REPAIR INDICATION ROLL-OUT MAP (Reference 21)

VECTRA DESIGN (STRUCT~)

OVERLAY TlilCKNESS

  • SEAL ORIGINAL PIPE WALL TlilCKNESS t LAYER TlilCKNESS For indication to be
  • a. surface flaw:

SID <. 0.4d

  • or S00 < OAd where: 2d = a 0054-00101-001-110 Revision 1 OlJTSIDE DIAMETER (00)----.

INSIDE DIAMETER (ID)

For indication to be a subsurface flaw:

s.1o L. 0.4d and S00 L_0.4d If indication is a surface flaw:.a = 2d + (S10 or S00)

Figure 4.0-3 SURFACE AND SUBSURF~CE PLANAR FLAWS

  • ~*/

. -~*

VECTRA

_. 24 -

. 0054-00101-001-110 Revision O Table 4.0-1 ALLOWABLE VOLUMETRIC PRESERVICE EXAMINATION PLANAR FLAWS Nominal Wall Thickness (inches)

. Aspect 0.312171 0.41181 1.0111

  • Ratio (a/ll Surface Subsurface Surface
  • Su.bsurface Surface Subsurface Flaw a/t Flaw a/t Flaw a/t Flaw a(t Flaw alt Flaw a/t

(%1

(%1

(%)

(%)*

(%1

(%1 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.

. i = flaw length. *

3.

t = nominal wall thickness.

4.

S. = flaw edge-to-surface distance.

5.

If S < 0.4d, corresponding flaw is* considered a surfac~ flaw>

If S L 0.4d, corresponding flaw is considered a* subsurface fiaw.

6.
  • Y = S/a. If Y > 1.0, use Y = 1.0. *

. 7.

8.

Interpolated from 0.312" and 1.0" values.

VECTRA 5.0 OVERLAY WELDMENT AND SYSTEM AFFECTS 0054-00101-001-110 Revision 1 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.

For a repaired weldment/component, this evaluation shall consider the affects of waterbacking as it affects residual stress produced by the

. overlay i~ combination with other applied system loads. The evaluation shall also addr.ess increases in piping system loads caused by overlay stiffness, deadweight, an.d axi~I shrinkage affects.

5.1 Weldment Evaluation The Reference 22 report presents an evaluation of the e!fectiveness 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-te~ weldments, the overlay effectiveness evaluation.

document presents the following potential root causes for. the indications discovered in the check v.alves:

a.

lntergranular Corrosion (IGC).

b.

lntergranular Stress Corrosion Cracking (IGSCC).

c.

Original construction casting or welding flaws~

As discussed in Secti.ons 2.2 and 2.6, t_he overlays applied to the check valve-to-tee weldments utilized the following implementation parameters:

. I

ti VECTRA 0054-00101~001-110 Revision O

a.

Filler metals having maximum carbon contents of 0.035% and as-deposited ferrite content's greater than 7. 5 FN.

b.

Machine GTAW techniques to apply parallel, overlapping, 360° circ1:-1mferential beads around a weldment with waterbacking.

c.

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

d.

A.maximum heat input of 28 K.joules/inch for at ieast 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. pro.vide the..

  • I.

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

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

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

. inherently resistant to aggressive failure mechanisms !?UCh a.s IGSCC. The

. actu.al. 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/

-'----- -* -.=____. v VE CT RA 0054-00101-001-110 Revision 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), overlay_s 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 boat 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 ne);(t refueling outage,.

a follow-up VOll:J.metric UT examination suggested that the steam blovv-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 surf~ce 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 wel~ment 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 metal. 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 boun(jed by the EPRl-recommended value

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

  • i, I
  • .. ~.\\/

VECTRA

. 0054-00101.,001-110 Revision 1 is judged to be equivalent to the EPRl-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 b~lance-of-plant life:' without 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 evalu.ations typi.cally result in weld overlay shrinkage (WOS) stresses, in unrepaired weldments away from rigid anchors/supports, of under 1,000 psi. was stresses have combined with other piping system stresses to create yield level stress magnitudes in weldments adjacent to rigid anchors only in cases involving short runs of piping with multipfo overlays.

As discussed in NUREG-0313 (Reference 27), the magnitude of sustained stresses acting* on stress-improved, 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

VECTRA 0054-00101-001-110 Revision 0

  • 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 v,ertical 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 s)lririkage.

1~

'\\

  • VECTRA.,..

0054-00101-001-110 Revision 0

[~V ~

J..

~.

I I I l

I I

I I

I I

I t

I Inside Surface Axial Residual Stress 0

,.1

  • u u

.. *~....,..OAfA'.*

,.. oi-'tlllllf AAIM. 111119~

..,...... ** **...... *,... ~.,..

~

111111

..... OIMllTI*

Axial Through-Wall Residual Stress

  • Figure5.1-1 TYPICAL POST-OVERLAY AXIAL RESIDUAL STRESS CONDITIONS (Reference 23)

~

  • a: c u

VECTRA 31 -

0054-00101-001-110 Revision 0 0.10 0.08 O.OB 0.07 0.08 0.08 0.CM 0.03 0.02 0.01 0

0 CLOSED SYMBOL - IGSCC LINES REPRESENT* LOWER BOUNDARY OPEN.SYMBOL *NO IGSCC HALF*FILLED SYMBOL

  • IGSCC - AT LEAST ONE SAMPLE OF STRESS CORROSION FAILURES CROSS*HATCHEO SYMBOL MINOR ENVIRONMENTAL INFLUENCE CFJ/CFB WELO~O t
  • . CJ t

t

<> 621°C 11 ltiOOF ln411

[> imo°F/48"

  • 0 AS-WE LOED. AW
  • L TS. AW
  • SHT

'V STELLITE HAROSURFACEO t>

[>

r9 0

0 0

0 0 0

[>

0 2

  • a

.B 10 12 14 16 18 20 22 24 26 28 FERRITE 1,.1 Figure 5.1-2 CARBON VS. FERRITE CONTENT AFFECTS ON IGSCC RESISTANCE (Reference 24)

JO

t

  • .~

.e VE CT RA 11.25X Magnification

. 1 SOX Magnification

  • Figure 5.1-3 BOAT SAMPLE METALLOGRAPHS (Reference 25) 0054-00101-001-110 Revision 0

VE CT RA

= 2'

= 9'. = 4'

  • T

= 7' '

(31661SO.WPG)

- 33*_

= 3' 1s* -s*

= 2' ELEVATION

= 46' PLAN VIEW Figu_re 5.2-1 0054-00101-001-110.

Revision 0

~ RIGID ANCHOR CK*ES3166 CHECK VAJ..\\/E..

TO-TEE WELDMENT (TYP.).

CONTAINMENT PENE'TfV' TION (TYP.)

CK-ESJ 166 PIPING SYSTEM LAYOUT (Reference 28)

VECTRA CK*ES3181 CHECK V/lJ..VE*

. TO-TEE WELDMENT (TYP.)

CONTAINMENT PENETRATION (TYP.)

ELEVATION

. ;. 67' PLAN VIEW Figure 5.2-2 0054-001OJ-001-110 Revision 0 0 2-WAY RESTRAIN":

= 20'

= 3' CK-ES3181 PIPING SYSTEM LAYOUT (Reference 29)

. :r

~,

VECTRA 6.0.

SUMMARY

AND CONCLUSIONS 0054-00101-001-110 Revision 0*

  • This report presents an evaluation of weld 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-504-1 (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 Sectior:i XI (Reference 10),

Paragraph IWB-3640 for each of the potential degradation mechanisms identified above. This* report also illustrates that pre-overlay volur:netric UT indicatio.ns confined within the CK-ES3166 and CK-ES3181 original pipe wall thicknesses of 0.70" and 0.73", respectively, must grow to depths

, greater thari 1.16" and 1.23" I respectively I 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 weldmen.ts

  • conservatively re-establis.h the original ASME BPVC structural factors of safety while providing a* corrosion:..resist"ant barrier-against unacceptably deep crack propagation for the balance:..of-plant life without creating new highly sensitized potentia1*1eak~ge paths.*

VECTRA 0054~00101-001-110 Revision 0 7.0 REFERENCES

1.

2..

3.
4.
5.

Consumers Power Company Palisades Nuclear Plant Drawing No.

M204, "System Diagram - Safety Injection, Containment Spray, &

Shutdown Cooling System", Sheet No. A, Revision 5.

Sargent & Lundy Document No, CMED~058599, "Check Valve Leak Root Cause, Engineering Analysis, and Repair/ Replacement Options", R~vision 0..

American Society of Mechanical Engineers (ASME) Boiler and

  • Pressure Vessel Cooe (BPVC) Case N-504-1, "Alternative Rules for Repair-o,f Class 1, 2, and 3 Aus"tenitic Stainless Steel Piping -

Sectio'n XI, Division 1 ",.Approval date: August 9,.1993 VECTRA Document No. 0054-00101-001-200, "Calculation Package - Containment Sump Check Valves Weld Overlay Repair

. Design.: Palisades Nuclear Plant", Revision 0. *

  • VECTRA Document No. 0054-00101-001-100, "ASME Section XI*

Rep.air Program - Weld, Ove.rlay Repairs to Austenitic Stainless *Steel

. Piping Weldments and Components - Palisades Nuclear Plant",

Revision 0.

6.

VECTRA Document No. 0054-00101-001-101, *"Procedure for Application and Examin~tion of Weld Overlay*Repairs to Austenitic*

Stair:iless Steel Piping Systems - Palisades Nuclear Plant",

Revision O.

7.

Gonsumers Power Company Purchase Order No. MM0027247.

8.

Consumers Power Company Nondestructive Testing Services Liqui~

Penetrant Examination Report, Examiner: 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 lnservice Inspection of Nuclear Power Plant Components", 1992 Edition with 1992 Addenda.

r 9

o

.,: ___ {;_.. ~*.~

VE CT RA 0054-00101-001--110 Revision 0

11.

_Consumers Power Company Nondestructive Testing Services Liquid 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 Nondestructi".'e 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 i.

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. 0. 244,10770.2, Dated: 3/24/94, 1 page (CK-ES3166)..

18. *Weld Overlay Data Sheet, W. 0. 24410771.0, Dated: 3/24/94, 1 page (CK-ES3181 ).
19.
  • Virginia Corporation Ultrasonic Examination Indication Record, Examiner: Y. Merey, Dated: 3/21/94, page 5 of 5, with Virginia Co.rporation Ultrasonic Examination Record - Profile/Plotting, -
      • Examiner: Y. Merey, Dated: 3/21/94, 2 pages (CK-ES3166).
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 Corporation Ultrasonic Examination Record - Profile/Plotting, Examiner: Y. Merey, Dated: 3/22/94, 2 pages (CK-ES3181).

.f,l *:!'.,,11 ~i.*

~

r*

'Y'

  • _*~,_it,..;.*:
  • ~' '

VECTRA 0054-00101-001-110 Revision 0-

22.

Sargent & Lundy Documef")t No. CMED-058617, "Evaluation of the Effectiveness 9f Code Case N-504-1 Repair for Proposed Root Causes for co*ntainment Sump Suction Check Valves", Revision 0.

. 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, Belgium, August 19-23, 1 S85, Volume D, pages 231-235.

24.

Hughes, N. R., Clarke, W. L., and Delwiche, D. E., "lntergranular

  • Stress-Corrosion Cracking Resistance of Auste,nitic Stainless Steel Castings", Stainless Steel Castings, ASTM STP 756, American

_Society of _Testing and Materials, 1982, pages 26-47.

25.

Froehlich, C. H., Axline~ J. w*., Do, H. Q., and Holland, D. G., "Field.

Verification of the Effectiveness of the Induction Heating Stress Improvement Process and Weld. Overlay R,ep_air Techniques on BWR

},\\ustenitic Stainless 'steel Recirculation System Piping Weldments'~,

  • 1 *2th Smirt Post Conference Seminar No_. 2, Assuring Structural' Integrity of Steel Reactor Pressure Boundary Components, Session 3

- Resolution* of integrity 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, Septembe_r 1981.

27.

United.States Nuclear Regulatory.Commission (USNRC) pocument

  • . No. NUREG-0313, "J"echnical 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 Inject.ion; Containment Spray, and.Shutdown Cooling System", Sheet 1 of 8, Revision 4.

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