Pacific Gas and Electric Company® James R. …Pacific Gas and Electric Company® February 1, 2011 PG&E Letter DCL~ 11-003 u.s. Nuclear Regulatory Commission ATTN: Document Control

Pacific Gas and Electric Company®

February 1, 2011

PG&E Letter DCL~ 11-003

u.s. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2

James R. Becker Site Vice President

Diablo Canyon Power Plant Mail Code 104/5/601 p. O. Box 56 Avila Beach, CA 93424

805.545.3462 Internal: 691.3462 Fax: 805.545.6445

Response to Telephone Conference Call Held on December 14,2010, Between the U.s. Nuclear Regulatory Commission and Pacific Gas and Electric Company Concerning Responses to Requests for Additional Information Related to the Diablo Canyon Nuclear Power Plant. Units 1 and 2, License Renewal Application

Dear Commissioners and Staff:

By letter dated November 23, 2009, Pacific Gas and Electric Company (PG&E) submitted an application to the U.S. Nuclear Regulatory Commission (NRC) for the renewal of Facility Operating Licenses DPR-80 and DPR-82, for Diablo Canyon Power Plant Units 1 and 2, respectively. The application included the license renewal application (LRA), and Applicant's Environmental Report - Operating License Renewal Stage.

On December 14, 2010, a telephone conference call between the NRC and representatives of PG&E was held to obtain clarification on PG&E's response to a request for additional information (RAI) submitted to the NRC in PG&E Letter DCL-10-155, dated December 06,2010, regarding RAI4.7.5-2 (Follow-up).

PG&E's supplemental information to the RAI response for which the staff requested information is provided in Enclosure 1. PG&E makes a commitment in the amended LRA Table A4-1, License Renewal Commitments, provided in Enclosure 2. LRA Amendment 39 is included in Enclosure 2 showing the changed pages with lineinlline-out annotations. Enclosure 3 contains Calculation 9000002974-001-00.

If you have any questions regarding this response, please contact Mr. Terence L. Grebel, License Renewal Project Manager, at (805) 545-4160.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance

. Callaway • Comanche Peak • Diablo <?anyon • Palo Verde • San Onofre • South Texas Project • Wolf Creek

Document Control Desk February 1, 2011 page 2

PG&E Letter DCL.,.11-003

I declare under penalty of perjury that the foregoing is true and correct.

Executed on February 1, 2011.

Sincerely,

James R. Becker Site Vice President

TLG/S0368814 Enclosures cc: Diablo Distribution cc/enc: Elmo E. Collins, NRC Region IV Regional Administrator

Nathanial B. Ferrer, NRC Project Manager, License Renewal Kimberly J. Green, NRC Project Manager, License Renewal Michael S. Peck, NRC Senior Resident Inspector Alan B. Wang, NRC Licensing Project Manager

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance

Callaway • Comanche Peak • Diablo Canyon • Palo Verde • San Onofre • South Texas Project • Wolf Creek

Enclosure 1 PG&E Letter DCL-11-003

Page 1 of 1

PG&E Supplements to Telephone Conference Call Held on December 14,2010, Concerning a Response to Request for Additional Information (RAI)

Submitted to the NRC in a Letter Dated December 06, 2010, Regarding RAI4.7.5-2 (Follow-up)

RAI 4. 7.5-2 (Follow-up)

In a telephone conference call held on December 14, 2010, the NRC reviewer requested additional information regarding PG&E's basis for concluding that Unit 1 residual heat removal piping weld WIC-95 is not service-related. PG&E agreed to supplement the response to RAI4. 7.5-2 (Follow-up).

PG&E Supplement to RAI4.7.5-2 (Follow-up)

As discussed in PG&E Letter DCL-10-155, dated December 06,2010, PG&E has evaluated the characteristics of the flaw as presented in the 1997 ASME Section XI ultrasonic testing (UT) and concluded that the flaw was not service-induced. A follow-up UT inspection in 2000 determined that the flaw had not grown and thus confirmed that this was a non service-induced defect.

The original 1997 flaw evaluation calculation did not consider intergranular stress corrosion cracking (SCC) as a potential flaw growth mechanism. The GALL Report indicates SCC rarely occurs at temperatures below 140°F when chemistry is maintained within industry standards. PG&E has maintained stable water chemistry throughout plant life such that the probability of SCC occurring at temperatures below 140°F is low. This weld in this piping system is normally exposed to temperatures of approximately 77°F, except for refueling outage startups and shutdowns. Based on a review of plant oRerating experience, this weld is exposed to temperatures in the range 140°F to 250°F for approximately 6 days during each refueling outage. Although PG&E does not believe that this flaw exhibits SCC characteristics, PG&E conservatively reevaluated the calculation to include SCC flaw growth in addition to fatigue flaw growth for time periods in which temperatures exceed 140°F, during refueling outages. The calculation demonstrated that the projected flaw growth would be acceptable through 2012 even if SCC was present. Calculation 9000002974-001-00 is provided in Enclosure 3.

PG&E will perform a regularly scheduled inspection of WIC-95 during the upcoming 1R17 refueling outage, scheduled for May 2012, to confirm the absence of servicerelated flaw growth. Should service-related flaw growth be identified in this inspection, it will be entered into the corrective action program and appropriate corrective action will be taken in accordance with ASME Section XI Code. In the absence of flaw growth, WIC-95 will continue to be inspected at a frequency required by the Inservice Inspection Program Plan. See amended LRA Table A4-1 in Enclosure 2.

Enclosure 2 PG&E Letter DCL-11-003 Page 1 of2

LRA Amendment 39

LRA Section Table A4-1

Enclosure 2 PG&E Letter DCL-11-003 Page 2 of 2

Table A4-1 License Renewal Commitments Item # Commitment

64 PG&E will perform a regularly scheduled lSI ultrasonic inspection of WIC-95 during the upcoming 1 R17 refueling outage, scheduled for May 2012, to confirm the absence of service-related flaw growth. Should service-related flaw growth be identified in this inspection, the corrective action program will be entered and appropriate corrective action will be taken in accordance with ASME Section XI Code. In absence of flaw growth, WIC-95 will continue to be inspected at a frequency required by the lSI Program Plan.

Appendix A Final Safety Analysis Report Supplement

LRA Implementation Section Schedule

B2.1.1 Prior to the completion of 1 R17

Calculation 9000002974-001-00

Enclosure 3 PG&E Letter DCL-11-003

Page 1 of 41

"Flaw Evaluation of Diablo Canyon Unit 1 Residual Heat Removal System Weld"

DCPP Form 69-20132 (04/13/10)

Design Calculation Cover Sheet

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CF3.1D4 Attachment 4 Page 1 of 1

Unit(s): _1 __ File No.: SAP Calculation No.: 9000002974

Design Calculation: ~ YES D NO System No.: -------- Legacy No.: MP- 6056 -------Responsible Group: _SP_R_O _________ _ Quality Classification: Q

-"'----

Structure, System or Component: RHR line 985, Weld WIC- 95

Subject: Evaluate Indication in RHR line 985, Weld WIC-95 for Acceptability under ASME Code Section XI, Considering Fatigue and Hypothetical SCC Flaw Growth. This is a stand-alone calculation.

Computer/Electronic Calculation: D YES ~ NO

Computer ID Application Name and Version Date of Latest InstallationNalidation Test

Calculation Page Index

Calculation Pacftage Contains pages No. of pages

Cover Sheet 1 1

Record of revisions 2 1

Calculation checklist 3 - 5 3

Calculation body 6 - 8 3

Attachments AU 1: 1 -1 12; AU 2: 1-18 30

Appendices: App 1: 2; App 2: 1 3

Other

TOTAL 41

CF3! ID4_-_Fonn_69-20132u3r1 0 MP6056R1.DOC 0201.1032

DCPP Form 69-21457 (04/07/10)

Design Calculation Record of Revisions

Reason for Revision I Prepared I LBIE I (Requesting By AD!

Document No.) Screen

Rev I Status I Pages No.! affected Ver. No.

[ ] Yes [ 1 No [ 1 N!A

[ ] Yes [ ] No [ ] N!A

[ ]Yes [ ] No [ 1 N!A

A. Insert PE stamp or seal

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CF3!1D4_-_Form_69-21457u3r10 MP6056R1.DOC 0128.1446

SAP Calculation No.:

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CF3.ID4 Attachment 5 Page 1 of1

9000002974

MP-6056

Registered Owner's Professional Acceptance

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DCPP Form 69-21459 (04/07/10)

Design Calculation Checklist

CF3.1D4 Attachment 7 Page 1 of3

SAP Calc. No.: 9000002974 ~~~~~~----------

Part. No.: 001 Version No.: 00

Legacy No.: ;;.;;M=.P_-..;;..6...;;..0=5....;;.6 _______ _

Item to Verify

Correct calculation number taken out in SAP - document number, part number, version number.

Originating document is entered in SAP as superior document (e.g., DCP number) and/or on Object Links tab (notification number).

Cover Page

Calculation number reflects SAP number and Legacy number.

Unit number is entered

Subject clearly stated.

If computer calculation, computer/application/validation information filled in.

Calculation Page Index completed.

Record of Revisions Page

Rev No., ~evised pages and reason for revision clearly identified.

Status matches status in SAP (except if it is PI in SAP, status is F here).

Prepared by, checked by and registered professional engineer blocks signed (full sigllature).

CF3.1D17 block signed if contractor-completed calc.

PE stamp block completed.

Calculation Body

Purpose is clear and includes the requesting document reference (e.g., DCP No).

Background is established clearly so that the reader can understand the situation without going back to the author.

Assumptions are validated or clearly indicated "Preliminary" if verification is required. If preliminary, SAP Notification No.:

Inputs validated or clearly indicated "Preliminary" if verification is required. If preliminary, SAP Notification No.:

As-built configuration is verified as required (steps 5.3.2d.7 and 5.3.2d.9).

Methodology described is concise and clear.

Acceptance criteria provided are clear.

Body of the calculation is clear so that another person can understand the analysis and the logic without going back to the author.

Results provides a precise solution to the stated purpose.

CF3! ID4_-_Form_ 69·21459u3r1 0 mp6056R1.DOC 0127.1224

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Margin assessment includes affect on existing margin (quantitative) or a qualitative assessment.

Margin data recorded using SRM module

Conclusion includes applicability and limitations.

Impact on other documents is performed (step 5.3.2k).

References are clearly identified as input, output and other references.

Attachments include references not readily retrievable.

.. All revised pages have the correct calc no, revision/version number (9*xxxx-yyy-zz).

. .L.BIE AD/Screen completed.

. :LBIE evaluation completed, when necessary.

Calculation input and output references correctly entered in SAP on Calculation record Object Links tab.

Verification

Check method A - Independent Review Of Calculation

Check method B - Alternate Calculation

o Comparison to a sufficient number of simplified calculations to support the calculation.

• Comparison to an analysis by an alternate verified method.

• Comparison to a similar verified calculation.

• Comparison to test results.

• Comparison to measured arid documented plant data for a comparable design.

• Compa~son to published data and correlation confirmed by industry experience.

• Other (describe)

Check method C - Critical Point Check

Approval:

Operations concurrence documented for any operator action( s).

Eng director approval to issue design with calc in "Preliminary" status. Ref.:

Calc Approved/Preliminary has a tracking operation off the closure order and is included on design engineering review requirements. No.: ___ _

PSRC approval jf LBIE evaluation is required.

PE stamp current for person signing as PE.

Approve as Final.

CF3!ID4_-_Form_69-21459u3r10 mp6056R1.DOC 0127.1224


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Calc status updated in SAP.

Calc Approved/Pending implementation has a tracking operation off the closure order.

Working copy of Approved Calculation package is transmitted to document services for filing in Library or if it is not stored in Library, returned to designated storage location.

Copy of the approved revision transmitted to engineering department clerk for transmitting to RMS.

CF3!1D4_-_Form_69-21459u3r10 mp6056R1.DOC 0127.1224


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DCP.P Form 69-20428 (04/07/10)

Design Calculation

«if Z 17-1',.. Oc~ I' - 00

G C1Fs CF3.ID4 Attachment 6

Page 1 of3

SAP Calc. No.: ..:::..9..::;..0..:::..0..:::..00=-.0=-:2=-:9:;...:7:....;4=--_____ _ Part No.: 001 Version No. 00 Unit: .L Legacy No.: ;:..::M=-P_-6=-.0=-:5;;..;6=--_______ _

Su~ect:Flaw Growth Evaluation, RHR Line 1-81-985-12, Weld WIP-95, SAPN

50366442

Reason for revision:

1. Purpose: This is a required field~ (Include the design change it supports, if any)Ref7.20/Ref7.21.2

Revise subject calculation in response to License Renewal Application RAI4.7.5-2 (Follow-up).

This revision supersedes MP-6056, Rev 0, approved 5/1/1997.

This revision updates MP-6056, Rev 0 as follows: a) Input piping run stresses are included per calculation 9000041129 - 000-00, PIMS Legacy 1226, RO (stress analysis 8-103, R12) b) Hypothetical stress corrosion cracking SCC crack growth is evaluated in response to NRC RAI 4.7.5-2, license extension.

2. Background:. This is a required field.Ref7.21.2

An indication determined to be non-service-induced was found during the 1997 normal Code inspection program. The indication did not present as ID-connected, and the UT did not reveal characteristics typical of stress corrosion cracking.' A follow-up UT inspection performed in the year 2000 revealed no change in the size of the indication, further suggesting that the flaw was not service-ind uced.

MP-6056, RO was performed in 1997 to calculate potential growth of the flaw under fatigue loading only, on the basis that SCC was not a valid mechanism. The calculation concluded the indication would meet Code acceptance criteria for the balance of plant life.

License Renewal Application RAI 4.7.5-2 (Follow-up) requested evaluation of the indication for continued acceptability under Code requirements, assuming the influence of both fatigue and the ruled-out SCC mechanism.

A consultant organization expert in the field was retained to perform the requested analysis. The resulting analysis is contained in two calculations, Structural Integrity Associates, Inc. (SI) documents numbered 1001564.301 and 1001564.302.

DCPP procedure CF3.ID17 specifies requirements for the review, acceptance and archiving of calculations performed by outside organizations. The SI calculations have been reviewed, accepted and archived according to those requirements. The SI calculations reflect the technical content of the calculation MP-6056, Revision 1 .evaluation. The SI calculations are attached to calculation MP-6056, Revision 1. MP-6056, Revision 1 is renamed 9000002974 -001-00 under the SAP system.

CF3!1D4_-_FOnTI_69-20428u3r10 MP6056R1.DOC 0201.0931

DCPP Form 69-20428 (04/07/10) Design Calculation

10. Conclusion:

/,l- -&17-r.-a-1:.f-oo .2:>t?Fa

(Include meeting Acceptance Criteria, if any; provide any limitations)

CF3.ID4 Attachment 6 Page 3 of3

a) Final flaw size, considering only the fatigue mechanism, remains acceptable at the end of the assumed operating period, i.e., 40 years beyonqJhe year 201 t. " ::-.

b) Final flaw size, considering both the fatigue and (hypothetical) SCC mechanisms, remains acceptable at the end current operating period, i.e., cycle 17. Should the 1 R17 outage inspection find flaw growth in excess of that expected from fatigue, the DCPP corrective action program will be entered for evaluation and disposition.

11. Impact on other documents: This is a required field (ensure notifications or tasks per procedure are written).T36016 MP-6056, Revision 0 is superseded in its entirety.

12. References:""

a. Input References: This is a required field (sources for inputs and assumptions). Calculations and procedures should be entered on the Object Links tab of the calculation record in SAP. Enter N/A if there is no reference.

90000041129-000-00; Structural Integrity Associates, Inc. documents, file numbers 1001564.301 and 1001564.302.

b. Output References: This is a required field (documents affected by the calculation) (include the information received from notifications or tasks sent): Calculations and procedures should be entered on the Object Links tab of the calculation record in SAP. Enter N/A if there is no reference.

See SI documents, file numbers 1001564.301 and 1001564.302

c. Other: This is a required field. Enter N/A if there is no reference (references used for performing the calculation).To4756 .

See SI documents, file numbers 1001564.301 and 1001564.302 SAPN 50366442

13. Enclosures and Attachments: This is a required field (Include copies of references not readily retrievable). LBIE Applicability Determination. SI documents number 1001564.301 and 1001564.302. E-mail from A Miessi to LF Goyette, confirming wall thickness and piping moment input data, 1/31/2011.

CF3I1D4_-_Form_69-20428u3r1 0 MP6056R1.DOC 0201.0931

r~ZJlr- oo/~ 00

File No.: 1001564.301

Project No.: 1001564

~ Structural Integrity Associates, Inc.®

CALCULATION PACKAGE Quality Program: rg] Nuclear D Commercial

PROJECT NAME:

Flaw Evaluation of Diablo Canyon Unit 1 Residual Heat Removal System Weld

CONTRACT NO.:

NA

CLIENT: PLANT:

Pacific Gas & Electric Company Diablo Canyon Power Plant, Unit 1

CALCULATION TITLE:

Crack Growth Rate Evaluation for Diablo Canyon Unit 1 RHR Stainless Steel Pipe

Document Revision

o

Affected Pages

1 - 12

Revision Description

Initial Issue

Project Manager Approval

Si2nature & Date

~I(J G. Angah Miessi GAM 1/27/11

Preparer(s) & Cbecker(s)

Signatures & Date

Barry Gordon BMG 1127111

t::~7.2Ei~!fb Anthony Giannuzzi

AJG 1127111

Page 1 of 12 F0306-01Rl

Table of Contents

1.0 INTRODUCTION ......................................................................................................... 3

2.0 TEClINICAL APPROACH ............... ~ .......................................................................... 3

3.0 EVALUATION OF FLAW IN THE WELD ................................................................ 3

4.0 EVALUATION OF ,FLAW IN THEHAZ - SCC PROPAGATIONRATE ................ 6

4.1 Controlled Potential Crack Growth Rate ........................................................... 6

4.2 Crack Growth Rate Adjustments for K and Conductivity ................................. 7

4.3 Effect of the Source of Conductivity - Boric Acid ............................................ 8

5.0 SUMJvIAR Y ................................................................................................................. 11

6.0 REFERENCES ............................................................................................................ 12

List of Tables

Table 4-1: Summary of Relevant Crack Growth Rate Data on Furnace Sensitized I Type 304 Stainless Steel [5] ................................................................................... 9

List of Figures

Figure 3-1: IGSCC Resistance in Weld Metal may be predicted by the Combined Influence of Carbon Content and Percent Ferrite [2] ............................................. 5

Figure 4-1: Effect of Temperature on Crack Growth Rate for Type 304 Stainless Steel in Impure Water Environments [5] ............................................................. 10

Figure 4-2: Comparison of Time-to-Failure in Oxygenated High-Purity Water and Borated Water for Sensitized Type 304 Stainless Steel [8] .......................... 11

File No.: 1001564.301 Revision: 0

Page 2 of 12

F0306-01Rl:

1.0 INTRODUCTION

A flaw evaluation was performed in May 1997 to disposition an ultrasonic testing (UT) indication in Weld WIC-95 at a piping tee of the residual heat removal (RHR) line of Diablo Canyon Power Plant (DCPP) Unitl. Because the RHR line is fabricated from stainless steel, the flaw evaluation considered fatigue as the sole crack growth mechanism. A subsequent DT examination in October 2000 showed that the flaw had not increased in size.

Although the May 1997 disposition eliminated stress corrosion cracking(SCC) as a potential flaw growth mechanism, recent activities associated with license renewal have deemed prudent the consideration of SCC in addition to fatigue. Because limitations of the DT technique preclude the positive location of the indication, i.e., within the weld or within the heat-affected zone (HAZ), SCC effects in both possible locations must be addressed. The objective of this calculation package is to document the analyses performed to 1) demonstrate that the duplex microstructure of the stainless steel weld is highly resistant to crack propagation, and 2) determine the appropriate SCC growth rate to use in a new flaw evaluation should the flaw be located in the HAZ of the piping tee weld joint.

2.0 TECHNICAL APPROACH

There have been numerous studies of SCC of wrought stainless steel base metal as well as stainless steel welds in various light water reactor type environments. These studies will be evaluated to demonstrate the resistance of stainless steel welds to SCC if the flaw is located in the weld, and to determine the appropriate SCC growth rate to apply for an evaluation of a flaw in the (sensitized) HAZ region of the weld joint.

3.0 EVALUATION OF FLAW IN THE WELD

Sensitization is a term that describes the precipitation of chromium carbides at the grain boundarie.s of austenitic stainless steel and nickel-base alloys and the subsequent susceptibility of these alloys to intergranular corrosion in aqueous media following certain heat treatments such as welding or furnace post weld heat treatments (PWHTs). The precipitation of chromium-rich carbides (e.g., Cr23C6 in austenitic stainless steel and Cr7C3 in Alloy 600) along grain boundaries depletes the region adjacent to the boundaries of chromium and induces susceptibility to intergranular corrosion due to the creation of a small anodic area surrounded by a much larger cathodic area. The most common example of sensitization is the intergranular corrosion (IGA) or intergranular stress corrosion cracking (lGSCC) susceptibility of the HAZ near the weld.

The superior resistance of duplex stainless steels to sensitization and the high resistance of the weld material to IGA and IGSCC have been known for over 70 years [1]. Many studies have demonstrated that the resistance of two-phase, austenitic-ferritic stainless steel weld metal and castings is a strong


Page 3 of12

F0306-01RL

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function of microstructure. Specifically, in work performed on wrought duplex stainless steels, the resistance to sensitization was shown to be a function of chemistry (e.g., carbon and chromium), as well as the amount and distribution of ferrite [1,2].

Figure 3-1 presents material failure / non-failure data on a graph of carbon versus ferrite for various types of specimens (e.g., full size pipes, constant extension rate, variable-load and constant load) exposed an environment of high purity water «1 JlS/cm) with 6 ± 2 ppm dissolved oxygen at a temperature 550°F (288°C) [2]. This plot represents the traditional approach of evaluating various casting heats. The results of this extensive test program revealed that for welded applications, a control on ferrite of 5% is recommended, and in furnace-sensitized applications, 12% ferrite will assure resistance to IGSCC. These measurements should be made after the mill solution heat treatment.

The U. S. Nuclear Regulatory Commission (NRC) considers weld metal and castings to be resistant to IGSCC: "Low carbon weld metal, including types 308L, 316L, 309L and similar grades, with a maximum carbon content of 0.035% and a minimum of7.5% ferrite (or 7.5 FN) as deposited" are considered resistant to IGSCC [3,4]. The NRC further states that "welds joining resistant material that meet the ASME Boiler and Pressure Vessel Code requirement of 5% ferrite (or 5 FN), but are below 7.5% ferrite (or 7.5 FN) may be sufficiently resistant, depending on carbon content and other factors. These will be evaluated on an individual case basis." Since these data represent IGSCC at 550°F (288°C), results at lower temperatures demonstrate even better resistance to stress corrosion cracking in these aggressive oxygenated environments.

Thus, should the subject nepp flaw be located in the weld, sec crack propagation is not anticipated due to the high SCC resistance of the duplex microstructure of the weld metal.


Page 4 of 12

F0306-01RI:

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0.05

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0.01

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UNES REPRESENT LOWER BOUNDARY OF STRESS CORROSION FAILURES "

CLOSED SVMBOl- tGsCC OPEN SYMBOL - .NO IGSCC HALF·FILLED SYMBOL .:..IGSCC - AT LEAST ONE SAMPLE

CROsS.HATCHEDSVMSOL -"MIN"OR ENviROOMENTAl INFLuENCE

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Figure 3-1: IGSCC Resistance in Weld Metal may be predicted by the Combined Influence of Carbon Content and Percent Ferrite [2]


Page 5 of 12

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4.0 EVALUATION OF FLAW IN THE HAZ - SCC PROPAGATION RATE

4.1 Controlled Potential Crack Growth Rate

Figure 4-1 presents the reversing DC potential drop (DCPD) technique crack growth rates of fracture mechanics compact tension (CT) specimens fabricated from furnace sensitized Type 304 stainless steel in higher purity water environments as a function of temperature. The overall plot reveals that the crack growth rate of furnace sensitized Type 304 stainless steel peaks at approximately 300 to 390°F (150 to 200°C) in higher purity water [5]. The observed maximum in IGSCC growth is attributed to two competing effects: 1) the increase in growth rate vs. temperature from increasing kinetics of mass transport, and 2) the decrease in growth rate vs. temperature from the decrease in corrosion potential due to decreasing dissolved oxygen content.

The environmental conditions for Diablo Canyon Unit 1 system of interest are the following [6, 10]:

Maximum temperature Operating temperature Boron Conductivity Maximum Total Oxidant

250°F (121°C)1 77°F (25°C) --2400 ppm 37 ~S/cm ",14 ppm2

Table 4-1 presents low temperature reversing DCPD crack growth rate [5] that is most relevant to the environmental conditions for the subject DCPP-l RHR piping, i.e., higher conductivity and higher dissolved oxygen, i.e., the data obtained on a furnace sensitized Type 304 stainless steel fracture mechanics compact tension specimen tested at a stress intensity of 30 ksiv'in (33 MPav'm) and exposed to an environment with dissolved oxygen content of 8.8 ppm. It should be noted that values above the limiting value of 3 ppm dissolved oxygen will have essentially the same affect on crack growth rates since the reduction of the cathodic reactants oxygen and hydrogen peroxide are diffusion limited.

Table 4-1 shows test conductivities of 0.580 J..lS/cm obtained by the addition of carbonic acid (H2C03); these crack growth rates may be considered non-conservative compared to the Diablo Canyon Unit 1 conductivity of37 f.!S/cm. However, as will be discussed below, the reagent by which the test conductivity is achieved is equally as important as the conductivity value. Also note that the stress intensity factor, K, of 30 ksbJin (33 MPav'm) in this test is significantly higher than the estimated K of 5 ksiv'in (5.5 MPa"m) for the flaw in the subject RHR piping.

1 The RHR. system is in service for a maximum of 6 days on heatup and 1 hour on cooldown, during which periods the metal temperature varies from 140 to 2500P (60 to 121°C). The calculation will consider flaw growth at the peak temperature of 2500 P (121°C) for the entire in service period. In accordance with NUREG-1801, Rev.l, flaw growth will not be considered at temperatures 14o"°P (60°C) and below [10]. 2 Total oxidant = dissolved oxygen content + 0.47 dissolved hydrogen peroxide content


Page 6 of 12

F0306-0IRI:

S).semt:lmal_rIfJf Assoaiares, Inc!'

4.2 Crack Growth Rate Adjustments for K and Conductivity

An IGSCC growth model for unirradiated, thermally sensitized stainless steels can be used to adjust the crack growth rates listed in Table 4-1 for both the stress intensity factor and conductivity.

This empirical model accounts for the variability of important IGSCC parameters such as coolant conductivity, stress intensity factor, K, temperature and electrochemical corrosion potential (ECP) in providing a conservative, yet realistic assessment of the crack growth rate [7]. Data from various sources were used to derive the empirical crack growth correlation, including work from Electric Power Research Institute (EPRI)-sponsored research, work sponsored by the U. S. Nuclear Regulatory Commission (NRC) and in-plant crack arrest verification system (CAVS) data as well as laboratory data developed by the General Electric Nuclear Energy (GENE). The combined database from all the sources was evaluated to ensure that only relevant data was used in the model development. This refined database was used to derive the crack growth correlation using pattern recognition and multivariate modeling tools.

For practical application to crack growth evaluation of stainless steel components, three approaches were developed for dispositions offlaws, 1) a K-independent approach, 2) a conservative 95th percentile Kdependent approach, and 3) a plant specific approach using actual water chemistry data. The plant specific approach using actual RHR line water chemistry data will be used here.

The best-fit for the 95th percentile model for the Type 304 stainless steel data is:

In(da) =2.181 In(K)-0.787 Cond-o,586 +0.00362 ECP+ 6730 -33.235

dt TABS

where: da/dt K Cond = ECP TABS SHE

crack growth rate (change in crack depth per unit time) stress intensity average conductivity (determined at room temperature) electrochemical corrosion potential temperature Standard Hydrogen Electrode

mm/s

IvIPa"'m J..I.S/cm mV(SHE) OK

This model will be used to calculate the crack growth rate factors between 0.580 and 37 J.l.S/cm conductivity and between 30 ksi"in (33 MPa"'m) and 5 ksi"in' (5.5 MPa"m).

It should be noted that while the higher DCPP conductivity of 37 J..I.S/cm versus 0.580 J.l.S/cm test value results in an increase in crack growth rate by a factor of 2.7, the decrease in K results in a factor of improvement (FOI) of 50, therefore offsetting the higher conductivity in the DCPP piping. The net reduction in crack growth rate would be 50/2.7 or a factor of approximately 18.5 and the crack growth rate for furnace sensitized stainless steel in Table 4-1 would be reduced by a factor of 18.5.


Page 7 of 12

F0306-01RI:

4.3 Effect of the Source of Conductivity - Boric Acid

As has been stated above, the particular reagent affecting water conductivity is important to the mechanism ofIGSCC, with the boric acid used at DCPP of demonstrated value in mitigating IGSCC in sensitized stainless steel [8]. Reference 8 cites the IGSCC susceptibility of several sensitized austenitic stainless steels (e.g., Types 304, 304L, 316, 316L and 316LN stainless steels) in 1) oxygenated highpurity deionized water (Le., chloride <0.05 ppm), and 2) borated water (i.e., 2,100 ppm as boron), at temperatures ranging from 86°F (30°C) to 464°F (240°C) via SCC test specimen configurations including uniaxial constant load, creviced bent beam and double U-bend [8].

A statistical analysis of these SCC test results at much higher temperatures than would be experienced at Diablo Canyon, i.e., 464°F (240°C) vs. 250°F (121°C) revealed that the median time-to-failure showed less IGSCC susceptibility for sensitized Type 304 stainless steel (0.06% C) uniaxial constant load specimens tested at an applied tensile stress of 49.8 ksi (35 kg/rom2

) in borated water (e.g., 132 hours) compared with that in high-purity to oxygenated (8 ppm 02) water (e.g., 54.5 hours).

Although the high temperature time to failure data presented in Figure 4-2 includes the time to initiate SCC plus the time to propagate the crack, the presence of 21 00 ppm boron as boric acid in the water suggests a factor of improvement of 132/54.5 or 2.4 in resistance to IGSCC.

As a result of plant startup and shutdown during each operating cycle, the RHR piping at DCPP may be exposed to temperatures above 140°F and as great as 250°F for a maximum time of six days (144 hours) during heatup and as long as 1 hour during shutdown [10]. SCC crack growth in borated water environments is not a consideration for austenitic stainless steels at temperatures of 140°F (60°C) and below as noted in the GALL report [9]. Therefore, considering the fact that no IGSCC is possible at the normal operating temperature of 77°F, the total SCC crack growth is calculated by using the following approach:

Examining Figure 4-1 over the entire temperature interval, it is noted that the crack growth is bounded by 1.6 x 10-2 mmlh (6.3 x 10-4 in/h) in aggressive chloride and sulfate containing environments. Correcting the data in Figure 4-1 at temperatures as great as 250°F for 1) increased conductivity (an increase by a factor of 2.7), 2) stress intensity factor (a decrease by a factor of 50), and 3) the presence of boric acid (a decrease by a factor of 2.4), results in an adjusted calculated crack growth rate of 124.2 mpy.


Page 8 of 12

F0306-01RI:

(-EZI" '1'" 0 e;> r ... 00 ~e( 1-t c- f{t,

Table 4-1: Summary of Relevant Crack Growth Rate Data on Furnace Sensitized Type 304 Stainless Steel [5]

Crack Temp., Heat Impurity, Cond., O2,

Growth °FeC) Number J.tM J.tS/cm ppm

Rate, mmls

77 (25) 71635 0.3 C03 0.580 8.8 2.78 x 10-7

212 (100) 71635 0.3 C03 0.580 8.8 10.3 x 10-7

302 (150) 71635 0.3 C03 0.580 8.8 5.22 x 10-1

392 (200) 71635 0.3 C03 0.580 8.8 5.75 x 10-"' 482 (250) 71635 0.3 C03 0.580 8.8 2.53 x 10-"' 550 (288) 71635 0.3" C03 0.580 8.8 0.97 x 10-<'

Notes: C03 is from the weak acid H2C03 from dissolved CO2 in air saturated water K = 30 ksi"in (33 MPa"m)

Crack Growth

Rate, inlh

3.94 X 10.5

14.57 X 10·:> 7.4 X 10·:> 8.15 X 10·:> 3.58 X 10.5

1.38 X 10-5

Crack Growth

Rate, mpy 345 1279 648 714 314 120


Page 9 of 12

F0306-01RI:

eSlnn:1u/'ll11ntsgrIly AssIlciams, Inc."

'C' .c E E

1.0E·01

1.0E·02

t'j;l

-; 1.0E·03 (~ " 10

0::: .c

~ C5 1.0E·04 ~ (.) co a-U

1.0E·05 F

t= r-r-r-r-

1.0E·06

25

- &. ~

.,

.,

A fI',a i"'"

~ ~

~

ABWR + Lab - Condo = 0.1 uS/em

EJBWR + Lab - Condo = 0.14 uS/em

o Lab - Condo = 0.2 uS/em

A Lab - Condo = 0.27 uS/em, R = 0.5

<> Lab· Condo = 0.58 uS/em, R = 0.5, 8 ppm 02 I

50 75 100 125 150 175

Temperature, °C

~.~ .,

t,

I,\. £"0 £)..

.. ~.tJ :J 0 ~

.• E-

L·~ A ~

A ."

,»f.

A

d -Ai

nm

200 225 250 275

.

. ~ '~~I::=

!J;:.\I .~

~ &.. •• 0

)-4 A •• -w-

- ...

300

CGR in/hr

1E·03

1E·04

1E·05

1E·06

1E·07

Figure 4-1: Effect of Temperature on Crack Growth Rate for Type 304 Stainless Steel in Impure Water Environments [5]


Note: (BWR + Lab = BWR and lab crack growth rate data at the indicated conductivity)

Page 10 of 12

F0306-0IRI:

'"

~

~ ~ ~

~ ~ \) ......

~ \)

o ~

S~ r

1~2fH-t:>C(_d 0 A1f1-

II fS 0,-

9S!p, '~--~--~~~~--------~ Pu re So.rlc' wat~r ocl,d " J.i+2.6

2!l~ 351<''1 ,~" "Q mu~-' SUS 304 sehSltlied Do2SpPfn ,

Figure 4-2: Comparison of Time-to-Failure in Oxygenated High-Purity Water and Borated Water for Sensitized Type 304 Stainless Steel [8]

5.0 SUMMARY

Based on the above discussion and present results, the results of this evaluation are summarized as follows:

1. If the flaw is located in the weld, see crack propagation is not anticipated due to the high see resistance of the duplex microstructure of the weld metal.

2. If the flaw is located in the HAZ, the sec propagation rate would be expected to be relatively high at 124.2 mpy but of short duration.

Therefore, if the flaw is located in the weld, only fatigue crack growth should be considered. For a flaw located in the HAZ, both fatigue and see crack growth should be considered and the see propagation rate of 124.2 mpy should be applied for the time spent at 250°F (121°C).


Page 11 of 12

F0306-01Rl

Strl1l:tufC:ii Biitiigrlty Associates, Inc!A

6.0 REFERENCES

1. H. Menendez, J. S. Chen and T. M. Devine, "The lnfluenc~ of Microstructure on the Sensitization Behavior of Duplex Stainless Steel Welds," paper 562 presented at Corrosion 89, NACE, New Orleans, Louisiana, April 17-21, 1989.

2. N. R. Hughes, W. L. Clarke and D. E. Delwiche, "Intergranular Stress Corrosion Cracking Resistance of Austenitic Stainless Steel Castings," Stainless Steel Castings. ASTM STP 756, V. G. Behal and A. S. Melilli, Eds. American Society for Testing and Materials, 1982, p. 26.

3. W. S. Hazelton and W. H. Koo, "Technical Report on Material Selection and Processing Guidelines for BWR Coolant Pressure Boundary Piping," NUREG-0313; Rev. 2, US Nuclear Regulatory Commission, January 1988.

4. US NRC Generic Letter 88-01, "NRC Position on IGSCC in BWR Austenitic Stainless Steel," January 25, 1988.

5. "BWRVIP-186: Effect of Water Chemistry and Temperature Transients on the IGSCC Growth Rates in BWR Components," EPR!, Palo Alto, CA 1016485.2008.

6. J. F. Gardner e-mail to C. Beard, et aI., "DCPP Unit 1 Flaw Evaluation for SCC - WIC-95," December t'6, 2010.

7. R. Pathania and R. Carter, "Technical Basis for BWRVIP Stainless Steel Crack Growth Correlations in BWRs," paper presented at PVP2007 2007 ASME Pressure Vessels and Piping Division Conference, July 22-26, 2007, San Antonio, Texas.

8. T. Tsuruta and S. Okallloto, "Stress Corrosion Cracking of Sensitized Austenitic Stainless Steels in High Temperature Water," Corrosion, Vol. 48, No.6, NACE, Houston, TX, June 1992, p. 518.

9. NUREG-1801, Revision 1, "Generic Aging Lessons learned (GALL) Report", Table 1, page 29, Table 2, page 45, Table 3, pages 47 and 48, September 2005.

10. E-mail from Christopher Beard to Angah Meissi, Subject: FW:DCPP Revised Temperature Data for RHR Calc., January 20, 2011.


Page 12 of 12

F0306-01Rl

AtfZ!:J( zt ;. y ;... 0 C /- 0 0 I ($ -If ~

!l)Stmciurallntegrity Associates, Inc.®

CALCULATION PACKAGE

File No.: 1001564.302

Project No.: 1001564

Quality Program: ~ Nuclear D Commercial

PROJECT NAME: Flaw Evaluation of Diablo Canyon Unit 1 Residual Heat Removal System Weld

CONTRACT NO.: N/A

CLIENT: PLANT: Pacific Gas & Electric Company Diablo Canyon Power Plant Unit 1

CALCULATION TITLE: ASME Code Section XI Flaw Evaluation of Indication in RHR Piping Weld WIC-95

Document Revision

o

Mfected Pages

1-9 A-I - A-9

Revision Description

Initial Issue

Project Manager Approval

Signature &, Date

~~ G. Angah Miessi GAM 01127111

Preparer(s) & Cbecker(s)

Signatures & Date

/ .. ~ .. : ......... "----_. ~

FabienHsu FH 01127/11

Checkers:

~ G. Angah Miessi GAM 01127111

p~~ Sh~s.Tan~

SST 01127111

Page 1 of9 F0306-01Rl

eSlnrIll'ul'lIllill11grlty Assoclat9s, Inc!'

Table of Contents

1.0 INTRODUCTION .................................................................................. ~ ...................... 3

2.0 TECHNICAL APPROACH .......................................................................................... 3

3.0 DESIGN INPUTS .......................................................................................................... 3

3.1 Pipe Dimensions ................................................................................................ 3

3.2 Material Properties ............................................................................................. 4

3.3 Applied Stresses ................................................................................................. 4

4.0 ASSUMPTIONS ............................................................................................................ 4

5.0 CALCULATIONS .............................. ~ ........................... : .............................................. 4

5.1 Allowable Flaw Size Calculation ..................................................................... .4

5.2 Craclc Growth Analysis ...................................................................................... 5

5.2.1 Fatigue Crack Growth Analysis ........................................................................ 6

5.2.2 Stress Corrosion Crack Growth Analysis .......................................................... 7

6.0 CONCLUSION .............................................................................................................. 7

7.0 REFERENCES .............................................................................................................. 8

APPENDIX A PC-CRACK OUTPUT FILE ....................................................................... A-I

List of Tables

Table 1: Allowable Part Through-Wall Circumferential Flaw Size ......................................... 9


Page 2 of9

F0306-01RL

4t(Z r£~flc( ... ool-~o .:?err8

1.0 INTRODUCTION

A flaw evaluation was performed in May 1997 to disposition an ultrasonic testing CUT) indication in WelCl WIC-95 at ~ piping tee of the residual heat removal (RHR) line of Diablo Canyon Power Plant (DCPP) Unitl. The RHR piping is 12~' NPS fabricated from stainless steel and the flaw is approximately 0.400 inches long by 0.200 inches deep. Because the RHR line is fabricated from stainless steel, the flaw evaluation considered fatigue as the sole crack growth mechanism. A subsequent UT examination [2] in October 2000 showed that the flaw had not increased in size.

Although the May 1997 disposition ruled out intergranular stress corrosion cracking (SCC) as a potential flaw growth mechanism, recent activities associated with license renewal have deemed prudent the consideration of SCC in addition to fatigue. Because limitations of the UT technique preclude the positive location of the indication, i.e., within the weld or within the heat-affected zone (HAZ), SCC effects in both possible locations must be addressed. Thus, this flaw evaluation will consider both fatigue and stress corrosion cracking as the damage mechanisms. In addition, the new loads associated with additional lead shielding added to the piping system the RHR piping will be considered in the flaw evaluation [3].

The objective of this calculation package is to document the new flaw evaluation of the indication in Weld WIC-95 including crack growth due to both fatigue and stress corrosion cracking under the new loads.

2.0 TECHNICAL APPROACH

The flaw evaluation consists of the following tasks:

• Perform a flaw evaluation based on the guidelines of ASIvlE B&PV Code, Section XI, IWB-3640 [1] to calculate the allowable flaw size for the RHR pipe weld. Stresses due to the applied loadings from the piping design analysis are used. Given that the material of the pipe is stainless steel, the flaw acceptance criteria based on elastic-plastic fracture mechanics (EPFM) was utilized based on Appendix C of Reference 1.

• Determine the stress intensity factors at the flaw and perform fatigue and stress corrosion crack growth analyses to compare end-of-evaluation period flaw size to the allowable flaw size computed above.

3.0 DESIGN INPUTS

3.1 Pipe Dimensions

The RHR pipe where the indication was discovered is a 12-inch pipe. The dimensions of the pipe are:


Page 3 of9

F0306-01Rl:

• Outer Diameter = 12.75 in; [2] • Wall Thickness = 0.41 in. [2]

3.2 Material Properties

The RHR system pipe containing the indication is fabricated from stainless steel per Reference~. Material properties for Type 304 stainless steel are obtained from Reference 6. At the maximum operating temperature of 250°F [5], the yield stress, Sy, is equal to 23,600 psi and the ultimate strength Su is 68,600 psi [6]. Therefore, the flow stress, (J' f' defmed as (Sy + Su)/2 is equal to 46,100 psi. For the

fatigue crack growth analysis, the fracture toughness for stainless steel is arbitrarily set to 200 ksi-in°.5.

3.3 Applied Stresses

The applicable stresses at the location of the indication are provided by Reference 3 which contains stress results from a piping analysis of the RHR piping system. Maximum stresses due to pressure, deadweight, seismic loadings and thermal expansion are extracted from the piping analysis at the node representing the weld (Node 453) for use in this evaluation and given below:

Pressure = Pressure + Dead Load'= Pressure + Dead Load + Seismic, Level B == Pressure + Dead Load + Seismic, Level C = Pressure + Dead Load + Seismic, Level D = Thermal Expansion =

4.0 ASSUMPTIONS

5430 psi (membrane) 5593 psi (membrane + bending) 5904 psi (membrane + bending) 6216 psi (membrane + bending) 8055 psi (membrane + bending) 3800 psi (bending)

1. The service life is assumed to be 40 years from the date of this evaluation. 2. It is conservatively assumed that the location of the flaw will experience the same

number of pressure + dead load + thermal cycles (400) as seismic cycles during the service life.

3. The weld is assumed to have been fabricated by Shielded Metal Arc Weld (SMA W).

5.0 CALCULATIONS

5.1 Allowable Flaw Size Calculation

The piping material is austenitic steel [2] and the weld is assumed to be SMA W. Per the screening criteria in ASME Code, Section XI, Appendix C [1], the elastic-plastic fracture mechanics (EPFM) based methodology described in Appendix C is used in this evaluation. The technical approach


Page 40f9

F0306-01RI:

consists of determining the critical flaw size (circumferential extent and through-wall depth) in the pipe that will cause the flawed pipe section to collapse.

The stress ratios are calculated as follows:

For combined loading,

and, for membrane stress,

where,

. ZSF (j" Stress Ratzo = m m

(j"f

Z = 1.3[1.0+0.01(NPS-4)]

0' m and O'b are the primary membrane and primary bending stresses, respectively. \

O'e is the secondary bending stress.

0' f is the flow stress is the flow stress which is calculated as (Sy + Su)/2.

SF;n is the safety factor for .membrane stress.

S~ is the safety factor for bending stress.

Z is a factor obtained from Reference 1. NPS is the nominal pipe size.

The maximum stresses for Pressure + Dead Load + Seismic for Service Level B are used for both Service Levels A and B. The material properties used in the allowable flaw size calculations are obtained from Section II, Part D of the ASME Code [6] at the RHR piping maximum operating temperature of2500P [5].

(1)

(2)

, (3)

The tables of ASME Code, Section XI, Appendix C [1] are used to determine the allowable flaw depthto-thickness ratio for each service level. Spreadsheet "DCPP Ul RHR Allowable Flaw Size.xls" is used for the allowable flaw size calculation,s of Unit 1. The results of the analysis are presented in Table 1 which shows various allowable flaw depths for various flaw lengths. It can be seen that the allowable flaw size is 75% of the wall thickness, i.e., 0.308 inches, for a flaw length up to 40% of the pipe circumference (144°).

5.2 Crack Growth Analysis

A linear elastic fracture mechanics and fatigue crack growth evaluation is performed for the observed indication using pc_CRACK™ [8]. The "Part Circumf. ID Surface Crack in Cylinder Under


Page 5 of9

F0306-01Rl:

Tension" fracture mechanics model is used in this evaluation. The model with a ratio of wall thickness to cylinder radius of 0.1 is used in the evaluation since the actual ratio is approximately

.0.067.

Using the applied stresses presented in Section 3.3, the stress intensity factors due to the different load combinations are determined.

5.2.1 Fatigue Crack Growth Analysis

Since the indication is surface connected, the end of life flaw size due to fatigue crack growth is calculated using the fatigue crack growth rate for austenitic steels exposed to water environments. Per Reference 7, the fatigue crack growth rate for austenitic steel in air environment along with an environment factor of2.0 for PWR environment can be used.

SubarticIes C-3200 and C-8400 of Reference 1 provide the fatigue crack growth rate for austenitic steel in air environments as:

where,

= =

=

~=C (ilK)n dN 0 I

stress intensity factor range (Kmax - Kmin) 3.3 CxS

where, C is a scaling parameter to account for temperature and is given by

(4)

(5)

where T is the metal temperature in OF (for T:::;800 OF), and S is a scaling parameter to account for R ratio and is given by:

S = 1.0 R:::;O = 1.0 + 1.8R 0:::; R:::; 0.79 = -43.35 + 57.97R 0.79:::; R < 1.0

with, R = Kmin / Kmax

The fatigue crack growth is performed for an assumed number of 400 cycles of pressure + deadweight + thermal loading. The initial flaw depth of 0.200 inches is used. The detailed results of


Page 6 of9

F0306·01Rl:

the fatigue crack growth analysis are presented in Appendix A. It can be seen that there is no crack growth due to fatigue after 40 years.

5.2.2 Stress Corrosion Crack Growth Analysis

The stress corrosion crack growth rate applicable to the flaw evaluation of the stainless steel RHR piping was determined in Reference 4. The rate of stress corrosion cracking calculated in Reference 4 is dependent on the stress intensity factor at the crack tip. Per Reference 9, during plant startup and shutdown for each operating cycle, the RHR piping may be exposed to temperatures above 1400 P and as great as 2500P for a maximum time of six days (144 hours) 'during heatup and as long as 1 hour during shutdown. Based on a stress intensity factor of 5 ksi-in1l2, and the peak evaluation temperature of250oP [9], the stress corrosion crack growth rate of 124.2 mils per year can be used based on Reference 4. Considering the 8 outages in the period from the year 2000 UT (lRI0) inspection until the next available refueling outage in 2012 (lRI7), the evaluation is performed for 1160 (i.e., 145 x 8) hours. It should be noted that using the bounding crack growth rate at 2500 P for the entire high temperature excursion is very conservative.

The stress intensity factor for the RHR piping flaw subjected to the sustained stresses of 5.593 ksi is calculated with pc_CRACK™ to be less than 4 ksi-in1l2, as presented in Appendix A. Therefore, the rates determined in Reference 4 are used to calculate a crack growth due to SCC of 0.016 inch during the 1160 total hours of high temperature excursions in 12 y,ears (8 operating ·cycles).

6.0 CONCLUSION

Crack growth analyses have been performed for the UT indication in Weld WIC-95 at a piping tee of the residual heat removal (RHR) line of Diablo Canyon Power Plant (DCPP) Unitl. The crack growth analysis considered both stress corrosion cracking and fatigue as the damage mechanisms.

Using a conservative assumption of 400 cycles of pressure + deadweight + thermal loading, the results of the analyses show that there is no crack propagation by fatigue and the total flaw growth by stress corrosion cracking is 0.016 inch in 12 years. Therefore, in 12 years (8 cycles), the flaw is predicted to grow to a depth of 0.216 inches, which is less than the allowable flaw depth of 0.308 inches.


Page 70f9

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7.0 REFERENCES

1. ASME Boiler and Pressure Vessel Code, Section XI, 2001 Edition and Addenda through 2003.

2. PG&E Calculation !v1P-6056, Evaluation of Crack Indication per lSI Inspection AR#A0430829, 5/2/97, SI File No. 1001564.201.

3. PG&E Stress analysis 8-103R12T Sheet A-2936 of A-2975, SI File No. 1001564.202.

4. Structural Integrity Calculation Package 1001564.301, Revision 0, "Crack Growth Rate Evaluation for Diablo Canyon Unit 1 RHR Stainless Steel Pipe".

5. Email from Christopher Beard (pGE) to Paul Hirschberg (SI) dated December 15,2010, "Re: DCPP Unit-1 Flaw Evaluation for SCC - WIC-95," SI File No. 1001564.203.

6. ASME Boiler & Pressure Vessel Code, Section II, 2001 Edition, with Addenda through 2003.

7. Section XI Task Group for Piping Flaw Evaluation, ASME Code, "Evaluation of Flaws in Austenitic Steel Piping," Journal of Pressure Vessel Technology, Vol. 108, August 1986.

8. pc-CRACK for Windows~ Version 3.1-98348, Structural Integrity Associates, 1998.

9. Email from Christopher Beard (PGE) to Angah Miessi (SI) dated January 20,2011, "FW: DCPP Revised Temperature Data for RHR Calc.," SI File No. 1001564.204.


Page 80f9

F0306-01Rl:

J

Table 1: Allowable Part Through-Wall Circumferential Flaw Size

Diablo Canyon Power Plant Unit 1 RHRPiping

Allowable-Flaw Size calculation

Dimensions

·Ro. RI .tnom Z

(hi) .(In) (In) . (In', -

6.38 5.97 0.41 47.5

P MX MY MZ Load (psi) . (In-Ib) (In-Ib)· .(ln~lb)

Pressure ow Thermal OcCasional 8 Occasional C Occasional 0

Stress Ratfas

Sehtlce O"m O"b O"e SFn, . level (ks1) ··(ksi) (ksl)

A 5.430 0;474 3.800 2.7

B 5.430 ·0.474 3.800 2.4

C 5.430 ·0.786 3.800 1.8

0 5.430 2.625 .3.BOO 1.3

Allowable Flaw Depth-fo-ThIckness Ratio

·NPS

Zfactrir . 1.404.

a (ksi)

5.430 .0.163

·3.800

.0.311

0.623 ·2.462

SFb

.2.3

2.0 :1.6

.1.4

Type 304 SS @ 250° F

S~ . Su (ksi) (ksl)

23.6 .68:6

23.6 68.6

23.6 68.6 ·23.6 68.6

Ratio of Flaw len~ to PlpeClrcumference;l/rcD 0

Service level 0

A 0.75

B 0.75

t 0.75

0 0.75


0.1 0.2

36 72 ·0.75 0.75

0.75 0.75

0.75 0.75

0.75 0.75

0.3 0.4 O.S 0.6.

FJawlength,b (degree) 108 144 lS0 216

0.75 0.75 0.708 0.66

.0.75 0.75 0.73 .0.69

0.75 0.75 0.72 0:68

0.75 .0.75 0.72 0.68

a, (ksl) .

46.1

46.1

46.1

46.1

I 0.75

·270

ri.6i

0.64

0.64

0.62

. stress Ratio 'Comb· :Memb

0.230 ·0.45

·0.238 .0.40 0.262 0.30

·0.328 0.21

Applicability Check

YES YES

YE.S YES

Page 9 of9

F0306-01RI:


APPENDIX A

PC-CRACK OUTPUT FILE

Page A-I of A-9

F0306-01Rl

pc-Crack Output File for Fatigue Evaluation

tm pc-CRACK for Windows

Version 3.1-98348 (C) Copyright '84 - '98

Structural Integrity Associates, Inc. 3315 Almaden Expressway, Suite 24

San Jose, CA 95118-1557 Voice: 408-978-8200 Fax: 408-978-8964

E-mail: [email protected]

Linear Elastic Fracture Mechanics

Date: Tue Dec 28 12:14:21 2010 Input Data and Results File: FATIGUE.LFM

Title: fatigue

Load Cases:

Stress Coefficients Case ID CO Cl C2

rhrl 9.393 o o

C3

o

Type

Coeff

------Through Wall Stresses for Load Cases With Stress Coeff-------Wall Case

Depth rhrl

0.0000 9.393 0.0308 9.393 0.0615 9.393 0.0923 9.393 0.1230 9.393 0.1538 9.393 0.1845 9.393 0.2153 9.393 0.2460 9.393 0.2767 9.393 0.3075 9.393

Crack Model: Part Circumf. ID Surface Crack in Cylinder Under Tension (t/R=O.l)

WARNING: The stress intensity factor (K) is calculated at the deepest point only. May be non-conservative in some cases.

Crack Parameters: Wall thickness: Crack depth:


0.4100 0.3075

Page A-2 of A-9

F0306-01RI

Crack length in degree: 6.8800 (6. 88<=2gamma<=360)

Co: membrane stress due to tension load. All other stress coefficients are neglected.

--------------------Stress Intensity Factor--------------------Crack Case

Size rhr1

0.0062 0.0123 0.0184 0.0246 0.0308 0.0369 0.0431 . 0.0492 0.0554 0.0615 0.0676 0.0738 0.0800 0.0861 0.0923 0.0984 0.1046 0.1107 0.1169 0.1230 0.1292 0.1353 0.1415 0.1476 0.1538 0.1599 0.1661 0.1722 0.1784 0.1845 0.1907 0.1968 0.2030 0.2091 0.2153 0.2214 0.2275 0.2337 0.2398 0.2460 0.2521 0.2583 0.2645 0.2706 0.2767 0.2829 0.2891

1. 45143 2.03358 2.46728 2.82202 3.12498 3.39024 3.62623

3.8385 4.03186 4.20883 4.37113 4.52045 4.65815 4.78533 4.90292

5.0117 5.11297 5.20803 5.29611 5.37764

5.453 5.52253 5.58654 5.64529 5.69903 5.74798

5.7893 5.81988 5.84591 5.86754 5.88493 5.89822 5.90755 5.91317 5.91516 5.91352 5.90836 5.89979 5.88787 5.87271 5.85437 5.83294 5.80848 5.78106 5.75074 5.71759 5.68166


Page A-3 of A-9

F0306·01RI

0.2952 0.3013 0.3075

5.64301 5.60168 5.55774

Crack Growth Laws:

Law ID: fatigue Type: Fatigue

Model: Paris

da/dN = c * (dK)An where

dK = Kmax - KInin dK > Kthres Kmax < Klc

Material parameters: c = 2.7560e-Ol0 n 3.3000

Kthres 0.0000

Material Fracture Toughness KIc:

Material ID: ssweld

Depth KIc

0.0000 200.0000

Initial crack size= Max. crack size=

Number of blocks=

0.2000 0.3075

40 Print increment of block= 1

Cycles Calc. Subblock /Time incre.

Print Crk. Grw. incre. Law

fatigue 10 1 40 fatigue

Subblock

fatigue

Crack growth results:

Total Subblock Cycles Cycles /Time /Time

Block: 1


Kmax Case ID Scale Factor

rhrl 1.0000

Krnax KInin DeltaK R

Mat. Klc

ssweld

Kmin Case ID Scale Factor

DaDn /DaDt Da a a/thk

Page A-4 of A-9

F0306-01RI

10 10 5.90e+000 O.OOe+OOO 5.90e+000 0.00 9.66e-008 9.66e-008

Block: 2 20 10 5.90e+000 O.OOe+OOO 5.90e+000 0.00 9.66e-008 9.66e-008





















0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

Page A-5 of A-9

F0306-01Rl


Block: 23 230 10 5.90e+000 O.OOe+OOO 5.90e+000 0.009.66e-008 9.66e-008



















End of pc-CRACK Output

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

0.2 0.49

Page A-6 of A-9

F0306-01Rl

pc-Crack Output File for SCC Evaluation

tm pc-CRACK for Windows

Version 3.1-98348 (C) Copyright '84 - '98

structural Integrity Associates, Inc. 3315 Almaden Expressway, Suite 24

San Jose, CA 95118-1557 Voice: 408-978-8200 Fax: 408-978-8964

E-mail: [email protected]

Linear Elastic Fracture Mechanics

Date: Tue Dec 28 09:57:53 2010 Input Data and Results File: SCC.LFM

Title: SCC

Load Cases:

Stress Coefficients Case ID CO Cl C2

rhr1 5.593 o o

C3

o

Type

Coeff

------Through Wall Stresses for Load Cases With Stress Coeff-------Wall Case

Depth rhrl

0.0000 0.0308 0.0615 0.0923 0.1230 0.1538 0.1845 0.2153 0.2460 0.2767 0.3075

5.593 5.593 5.593 5.593 5.593 5.593 5.593 5.593 5.593 5.593 5.593

Crack Model: Part Circumf. ID Surface Crack in Cylinder Under Tension (t/R=O.l)

WARNING: The stress intensity factor (K) is calculated at the deepest point only. May be non-conservative in some cases.


Page A-7 of A-9

F0306-01Rl

Crack Parameters: Wall thickness: Crack depth: Crack length in degree:

(6.88<=2gamrna<=360) Co: membrane stress due

0.4100 0.3075 6.8800

to tension load. All other stress coefficients are neglected.

--------------------Stress Intensity Factor--------------------Crack Case

Size rhr1

0.0062 0.0123 0.0184 0.0246 0.0308 0.0369 0.0431 0.0492 0.0554 0.0615 0.0676 0.0738 0.0800 0.0861 0.0923 0.0984 0.1046 0.1107 0.1169 0.1230 0.1292 0.1353

'0.1415 0.1476 0.1538 0.1599 0.1661 0.1722 0.1784 0.1845 0.1907 0.1968 0.2030 0.2091 0.2153 0.2214 0.2275 0.2337 0.2398 0.2460 0.2521 0.2583 0.2645

0.864245 1.21088 1.46912 1.68035 1.86075

2.0187 2.15922 2.28561 2.40074 2.50612 2.60276 2.69167 2.77366 2.84939 2.9194;1. 2.98418 3.04449 3.10109 3.15353 3.20208 3.24695 3.28836 3.32647 3.36145 3.39345

3.4226 3.4472

3.46541 3.48091 3.49379 3.50414 3.51206 3.51761 3.52096 3.52214 3.52117

3.5181 3.51299

3.5059 3.49687 3.48595 I

3.47319 3.45862


Page A-8 of A-9

F0306-01RI

0.2706 0.2767 0.2'829 0.2891 0.2952 0.3013 0.3075

3.44229 3.42424

3.4045 3.38311 3.36009 3.33549 3.30932


I'e o Frs

End of pc-CRACK Output

Page A-9 of A-9

F0306-01Rl

Form 69-10430 (07/06/10) A,ri'1. la-Fl.·

TS3.1D2 Attachment 8.1

Page 1 of2

LBtE Screen - Applicability Determination

1. Proposed Activity/Implementing Document No: Unit: Imp Doc Rev No: Revise Calculation MP-6056/ 9000002974-001-00 in response ~1 02 01&2 0 to License Renewal RAI 4.7.5-2 (Followup)

Briefly describe what is being changed and why:

Calculation MP-6056 is being revised to Revision 1, i.e., 9000002974-001-00. Calculation MP-6056 is the assessment of a non-service-induced indication in RHR line 985 weld WIC-95 for ASME Code acceptability during future plant operation. The indication was proven acceptable for the life of the plant. License renewal activities generated a NRC RAI4.7.5-2 (Followup) requesting calculation of flaw growth considering both fatigue and SCC mechanisms. New calculations were performed by an industry expert in flaw evaluation, Structural Integrity Associates, Inc. (SI), calculations number 1001564.301 and 1001564.302. The calculations have been reviewed ana approved by PG&E in accordance with CF3.1017. The calculations are attached to MP-6056, Revision 1. Results and conclusions of the Revision 0 calculation are unchanged in the Revision 1 calculation.

2. Applicability Determination (refer to TS3.102, Appendix 7.1 Section 2 for instructions) Ref. TS3.1D2 Does the proposed activity involve: Appendix 7.1

2.a A change to the FacilityllSFSI Operating License (Ol), Environmental Protection Ov ~N Block2.a Plan (EPP) or Technical Specifications (TS)?

2.b A change to the Quality Assurance Program? OV ~N Block2.b

2.c A change to the Security Plan? OV ~N Block2.c

2.d A change to the Emergency Plan? Ov ~N Block 2.d

2.e A change to the Inservice Testing (1ST) Program Plan? Ov ~N Block2.e

2.f A change to the Inservice Inspection (lSI) Program Plan? oV ~N Block 2.f

2.g A change to the Fire Protection Program? OV ~N Block 2.g

2.h A noncompliance with the Environmental Protection Plan or may create a situation Ov ~N Block2.h adverse to the environment?

2.i A change to the FSARU (including documents incorporated by reference) excluded Ov ~N Block 2.i from the requirement to perform a 50.59/72.48 review?

2.j Maintenance that restores SSCs to their original or newly approved designed Ov '~N Block 2.j condition? (Check "No" if activity is related to ISFSI.)

2.k A temporary alteration supporting maintenance that will be in effect during at-power Ov ~N Block 2.k operations for 90 days or less? (Check "No" if activity is related to ISFSI.)

2.1 Managerial or administrative procedure/process controlled under 10 CFR 50, App. B? ~v ON Block 2.1

2.m Regulatory commitment not covered by another regulatory based change process? OV ~N Block2.m

2.n An impact to other plant specific programs (e.g., the ODCM) that are controlled by OV ~N Block 2.n regulations, the Ol, or TS?

3. Applicability Determination Conclusions (refer to TS3.ID2, Appendix 7.1 Section 3 for instructions):

~ A 10 CFR 50.59 or 72.48 screen is NOT required because All aspects of the activity are controlled by one or more of the processes listed above, or have been approved by the NRC, or covered in full in another lBIE review.

o A 10 CFR 50.59 or 72.48 screen will be completed because some or all the aspects of the aqtivity are not controlled by any ofthe processes listed above or cannot be exempted from the 10 CFR 50.59/72.48 screen.

4. Does the proposed activity involve a change to the plant where the change requires a safety assessment? I 0 V I ~ N (refer to TS3.1D2, Appendix 7.1 Section 4 for instructions)

PG&E Diablo Canyon

Form 69·10430 (07/06/10) LBIE Screen - Applicability Determination

Arr "I' 1 . r TS3.1D2 Attachment 8.1

e. c:r t/-Page 2 of2

5. Remarks: {Use this section to provide sufficient justification(s} per TS3.1D2, step 5.1.3 for determinations in step 2 and con~lusion in step 3.} A Screen is not required on the basis that calculations and revisions thereto are fully controlled under DCPP procedures that are controlled under 10 CFR 50, Appendix B. A Safety Asessment is not required on the basis of Procedure TS3.1D2, Appendix 7.6, Section 4.b, Exclusions. The proposed activity (Le., revising the calculation with no net result in conclusion from that of the original revision calculation) has no safety significance.

-TL,3/E' PG&E Acceptance Signature: {Qual: TLBIEAD or TLBIE} (N/A if performed or reviewed by PG&E)

/VA Refer to TS3.1D2, Section 6, for instructions on handling completed forms.

PG&E Diablo Canyon

Date:

Date: 'l-

Date:

Print Last Name: Goyette

Print Last Name:

I f f<f+A-rt2. , Print Last Name:

Goyette, Lee /~ 2?IY- 00 I- C'o

From:

Sent:

To:

Miessi, Angah [[email protected]]

Monday, January 31, 2011 7:50 PM

Goyette, Lee; Miessi, Angah

Cc: Khatri, Suresh

Subject: RE: SIA Calcs 1001564.301, Rev 0; 1001564.302, Rev 0

My responses a re shown below.

Angab From: Goyette, Lee [mailto:[email protected]] Sent: Monday, January 31, 2011 5:32 PM To: Miessi, Angah Cc: Khatri, Suresh Subject: SIA Cales 1001564.301, Rev 0; 1001564.302, Rev 0 Importance: High

Ref: SIA Cales 1001564.301, Rev 0; 1001564.302, Rev 0

Angah, Please confirm the following per our telecon:

1) Subject piping system nominal wall thickness is O.375-inch. Run pipe stresses are calculated at 0.375-inch thickness. The actual wall thickness at the point of interest is 0.41-inch. Please confirm that the use of actual wall thickness as used in the calculations is correct and acceptable under the ASME Code.

Yes, Section XI of the ASME Code allows the use of actual pipe dimensions at the location of the flaw for the allowable flaw and crack growth evaluations.

2) Run piping moments OW, Pressure and Thermal are used in the analysis performed in section 5.2.1 of 1001564.302, without consideration of seismic moments. Please confirm that the use of DW, Pressure and Thermal, without considering Seismic is correct and acceptable under the ASME Code.

Yes, Section XI stipulates that crack growth is to be performed for the "operating conditions and transients that apply during the evaluation period" and that "cumulative fatigue crack growth analysis of components need not include emergency and faulted conditions". As such, seismic loads are generally inconsequential due to the stress magnitudes and number of cycles associated with them as compared to thermal transients. In this RHR piping flaw evaluation, the Level B seismic load which could be conservatively considered for crack growth is only 0.311 ksi, which is small compared to the 9.393 ksi total stress used in the analysis. Thus, the consideration of seismic stresses would not change the results of the crack growth analysis.

Lee

Lee F. Goyette, P .E.

2/1/2011

Pacific Gas and Electric Company® James R. …Pacific Gas and Electric Company® February 1, 2011 PG&E Letter DCL~ 11-003 u.s. Nuclear Regulatory Commission ATTN: Document Control

Documents