L-10-131, Additional Information Regarding 10 CFR 50.55a Request RR-A34 for Alternative Repair Methods for Reactor Pressure Vessel Head Penetration Nozzles

Additional Information Regarding 10 CFR 50.55a Request RR-A34 for Alternative Repair Methods for Reactor Pressure Vessel Head Penetration Nozzles

ML101160438
Person / Time
Site:	Davis Besse
Issue date:	04/21/2010
From:	Allen B FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-10-131, TAC ME3703
Download: ML101160438 (66)

Text

FENOC Withhold From Public Disclosure Under 10 CFR 2.390 5501 North State Route 2 FirstEnergyNuclear OperatingCompany Oak Harbor,Ohio 43449 Barty S. Allen 419-321-7676 Vice President - Nuclear Fax: 419-321-7582 April 21, 2010 L-1 0-131 10 CFR 50.55a ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Davis-Besse Nuclear Power Station Docket No. 50-346, License No. NPF-3 Additional Information Reqarding 10 CFR 50.55a Request RR-A34 for Alternative Repair Methods for Reactor Pressure Vessel Head Penetration Nozzles (TAC No. ME3703)

By correspondence dated April 1, 2010, FirstEnergy Nuclear Operating Company (FENOC) submitted 10 CFR 50.55a Request RR-A34, which requests Nuclear Regulatory Commission (NRC) approval of alternative methods to repair the reactor pressure vessel (RPV) penetration nozzles at the Davis-Besse Nuclear Power Station (DBNPS). By correspondence dated April 9, 2010, the NRC staff requested additional information to complete its review of RR-A34. Responses were provided by correspondence dated April 16, 2010.

In support of the NRC review of RR-A34, "DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repai' is enclosed. The complete J-groove weld analysis contains proprietary information that is to be withheld from public disclosure pursuant to 10 CFR 2.390. Therefore, Enclosure A provides a nonproprietary version of the AREVA J-groove weld analysis for full public disclosure. Enclosure B contains the AREVA affidavit to support the disclosure request for the proprietary J-groove weld analysis, and Enclosure C provides the complete J-groove weld analysis that contains sections to be withheld from public disclosure.

Withhold From Public Disclosure Under 10 CFR 2.390 When separated from Enclosure C, this document is decontrolled. Aii+7K~~u-9

Withhold From Public Disclosure Under 10 CFR 2.390 Davis-Besse Nuclear Power Station L-1 0-131 Page 2 The proposed alternatives are to be implemented during the ongoing DBNPS maintenance and refueling outage. Therefore, as stated in the correspondence dated April 1, 2010, FENOC is requesting expedited NRC staff review and approval of the proposed alternative, RR-A34.

There are no regulatory commitments contained in this letter. If there are any questions, or if additional information is required, please contact Mr. Thomas A. Lentz, Manager - Fleet Licensing, at 330-761-6071.

Sincerely, Barry S. Allen I

Enclosures:

A. DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair (Nonproprietary)

B. Affidavit for DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair C. DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair (Proprietary) cc: NRC Region III Administrator (Enclosure A only)

NRC Resident Inspector (Enclosure A only)

Nuclear Reactor Regulation Project Manager (Enclosure A only)

Utility Radiological Safety Board (Enclosure A only)

Withhold From Public Disclosure Under 10 CFR 2.390 When separated from Enclosure C, this document is decontrolled.

Enclosure A L-1 0-131 DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair (Nonproprietary)

(59 pages follow)

Controlled Document0402-01-FOl (20697) (Rev. 014, 04/13/2009)

A CALCULATION

SUMMARY

SHEET (CSS)

AREVA Document No. 32 - 9136508 - 001 Safety Related: Z Yes E]No Title DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair PURPOSE AND

SUMMARY

OF RESULTS:

Purpose This document is a non-proprietary version of AREVA NP Document 32-9134664-002. The AREVA NP proprietary information removed from 32-9134664-002 is indicated by a pair of braces "{ }".

The purpose of the present analysis is to determine from a fracture mechanics viewpoint the suitability of leaving degraded J-groove weld and butter material in the Davis Besse Unit 1 reactor vessel head following the repair of a Control Rod Drive Mechanism (CRDM) nozzle by the ID temper bead weld procedure. It is postulated that a small flaw in the head would combine with a large stress corrosion crack in the weld and butter to form a radial corner flaw that would propagate into the low alloy steel head by fatigue crack growth under cyclic loading conditions.

The purpose of Revision 1 is to change the indicator for removed proprietary information from square brackets

"[ ]"to braces "{ }".

Summary of Results Based on a combination of linear elastic and elastic plastic fracture mechanics analysis of a postulated remaining flaw in the original Alloy 182 J-groove weld and butter material, a Davis Besse Unit 1 CRDM nozzle is considered to be acceptable for at least 4 years of operation following an IDTB weld repair. The controlling loading condition was determined to be the rod withdrawal transient, for which it was shown that with safety factors of 3 on primary loads and 1.5 on secondary loads that the applied tearing modulus (11.63) was still less than the tearing modulus of the low alloy steel head material (12.93).

• This document consists of pages 1 - 46, A-i, B B-3, C C-4, D D-3, and E E-2.

THE DOCUMENT CONTAINS ASSUMPTIONS THAT SHALL BE THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: VERIFIED PRIOR TO USE CODENERSION/REV CODENERSION/REV ED YES ANSYS/10/0 Z NO AREVA NP Inc., an AREVA and Siemens company Page 1 of 59*

Controlled Document A

A1R EVA 0402-01-FOl (20697) (Rev. 014, 04/13/2009)

AREVA NP Inc.,

Document No. 32-9136508-001 an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Review Method: [ Design Review (Detailed Check)

D Alternate Calculation Signature Block P/R/A Name and Title and Pages/Sections

• (printed or typed) Signature LP/LR Date Prepared/Reviewed/Approved D. E. Killian P All Advisory Engineer IC)

S. H. Mahmoud R All Engineer IV /7 0-l T. M. Wiger A All Unit Manager Note: P/R/A designates Preparer (P), Reviewer (R), Approver (A);

LP/LR designates Lead Preparer (LP), Lead Reviewer (LR)

Project Manager Approval of Customer References (N/A if not applicable)

Name Title (printed or typed) (printed or typed) gnpture Date R. J. Baker, Jr. Project Manager 2 Mentoring Information (not required per 0402-01)

Name Title Mentor to:

(printed or typed) (printed or typed) (P/R) Signature Date N/R _r Page 2

Controlled Document A 0402-01-FOl (20697) (Rev. 014, 04/13/2009)

AREVA.

AREVA NP Inc.,

Document No. 32-9136508-001 an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Record of Revision Revision PageslSectionsl No. Date Paragraphs Changed Brief Description I Change Authorization 000 04/2010 All Original release 001 04/2010 Page 20 Changed yield and ultimate strengths in Table 4-1 Pages 25-26 Pages reflect changes to Section 4.3 to enhance the description of the Rod Withdrawal Transient Pages 32-46 Calculations modified to account for changes to yield and ultimate strengths in Table 4-1 Throughout Added square brackets ("[ ]") to indicate removed proprietary information 002 04/2010 Throughout Changed indicator for removed proprietary information from square brackets ("[ ]") to braces ("{ }")

Page 3

Controlled Document A

ARE VA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table of Contents Page SIGNATURE BLOCK .................................................... ........................................................................... 2 RECO RD O F REVISIO N .............................................. ........................................................................... 3 LIST OF TABLES ......................................................... ............................................................................ 6 LIST OF FIG URES .................................................... ......................................................... 7 1.0 INTRO DUCTION ............................................... ........................................................................... 8 2.0 ANALYTICAL METHO DOLOGY ............................................................................................. 11 2.1 Stress Intensity Factor Solution ........................................... 13 2.1.1 Finite Element Crack Model ......................................................................................... 13 2.1.2 Stress Mapping ................................................................................................................. 13 2.1.3 Crack Growth Considerations .................................................................................... 15 2.1.4 Plastic Zone Correction ............................................................................................... 15 2.2 Linear-Elastic Facture Mechanics ............................................................................................. 16 2.3 Elastic-Plastic Facture Mechanics ............................................................................................. 16 2.3.1 Screening Criteria ...................................................................................................... 16 2.3.2 Flaw Stability and Crack Driving Force ...................................................................... 16 3.0 ASSUM PTIONS .......................................................................................................................... 19 3.1 Unverified Assumptions ................................. ........................................................................... 19 3.2 Justified Assumptions .................................... ................................................................................. 19 3.3 Modeling Simplifications ............................................................................................................ 19 4.0 DESIGN INPUTS ....................................................................................................................... 20 4.1 Materials ............................................................ 20 4.1.1 Mechanical and Thermal Properties ........................................................................... 20 4.1.2 Reference Temperature .......................................... 22 4.1.3 Fracture Toughness ........................ ............................................................................ 22 4.1.4 J-integral Resistance Curve ....... ................................................................................ 22 4.1.5 Fatigue Crack Growth Rate ............ I............................................................................ 24 4.2 Basic Geometry ................................................................................................................................ 25 4.3 Operating Transients ...................................................................................................................... 25 4.4 Applied Stresses ..................................................... 26 Page 4

Controlled Document A

ARE EVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table of Contents (continued)

Page 4 .4 .1 Re sid ua l S tre sse s ........................... ................................................................................. 2 6 4.4.2 O perational Stresses .................................................................................................... 26 5.0 CALCULATIONS ........................................... . . ................................... .......... 31 5.1 Fatigue Crack Growth ....................................................... 31 5.2 LE FM Flaw Evaluations .................................................................................................................. 35 5 .3 E P F M F law E valuations ................................................................................................................. 36 6.0

SUMMARY

OF RESULTS AND CONCLUSIONS .................................................................. 44 6 .1 S um ma ry of Results ....................................................................................................................... 44 6 .2 C o n c lu s io n ..................................................... ................................................................................. 44 7 .0 R E F E R E NC E S ............................................................................................................................ 45 APPENDIX A: VERIFICATION OF COMPUTER CODE ANSYS ................................................................ A-1 APPENDIX B: COMPUTER FILES IN COLDSTOR ..................................................................................... B-1 APPENDIX C: FINITE ELEMENT CRACK MODEL .......................................................................................... C-1 APPENDIX D: FINITE ELEMENT STRESS MODEL ................................................................................... D-1 APPENDIX E: STRESS INTENSITY FACTOR DUE TO PRESSURE ......................................................... E-1 Page 5

Controlled Document A

A RE VA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair List of Tables Page Table 1-1: Safety Factors for Flaw Acceptance .................................................................................. 9 Table 4-1: Material Properties for Head ....................... ..................................................................... 20 Table 4-2: Material Properties for Weld Metal . ..... ............................................................. 21 Table 4-3: Material Properties for Cladding ................. .................................................................... 21 Table 4-4: Transient Analysis Time Points for Operational Stresses ................................................ 30 Table 5-1: Flaw Growth and LEFM Evaluation ............ :......................................................................... 32 Table 5-2: EPFM Evaluation for Shutdown Conditions ..................................................................... 38 Table 5-3: EPFM Evaluation for Heatup/Cooldown with Reactor Trip .................................................. 39 Table 5-4: EPFM Evaluation for Rod Withdrawal Accident ............................................................... 40 Page 6

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair List of Figures Page Figure 1-1: ID Temper Bead Weld Repair ................... .................................................................... 10 Figure 2-1: Postulated Radial Flaw on Uphill Side ........ ................................................................... 12 Figure 2-2: Finite Element Crack Model .......................................................................................... 14 Figure 4-1: Correlation of Coefficient, C, of Power Law with Charpy V-Notch Upper Shelf Energy ...... 23 Figure 4-2: Correlation of Exponent, m, of Power Law ,with Coefficient, C, and Flow Stress, GO ........... 23 Figure 4-3: DEl Finite Element Stress Model ............... ..................................................................... 27 Figure 4-4: DEI Finite Element Stress Model - Weld Region ........................................................... 28 Figure 4-5: Finite Element Stress Model for Operational Stresses .................................................. 29 Figure 5-1: J-T Diagram for Shutdown Conditions ....... .................................................................... 41 Figure 5-2: J-T Diagram for Heatup/Cooldown with Reactor Trip .................................................... 42 Figure 5-3: J-T Diagram for Rod Withdrawal Accident i.................................................................... 43 Page 7

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair

1.0 INTRODUCTION

A March 2010 inspection of Alloy 600 control rod drive mechanism (CRDM) nozzles in the reactor vessel closure head (RVCH) at Davis Besse Unit 1 revealed defects in several nozzles and nozzle-to-RVCH partial penetration welds, along with evidence of leakage as manifested by deposits of boric acid crystals on the outer surface of the head. The original RVCH at Davis Besse Unit I (DB-1) was replaced in 2002 with the closure head from a suspended Midland plant owned by Consumers Power Company. It is currently believed that the leakage in, the DB-1 RVCH was caused by primary water stress corrosion cracking (PWSCC) of the susceptible Alloy 600 nozzles and Alloy 182 welds.

Degraded nozzles at DB-1 are to be repaired using an inside diameter temper bead (IDTB) welding procedure wherein the lower portion of a nozzle is removed by a boring procedure and the remaining portion of the nozzle is welded to the low alloy steel reactor vessel head above the original Alloy 182 J-groove attachment weld, as shown in Figure 1-1. The repair is more fully described by the design drawing [1] and the design specification [2]. Although the remnant J-groove weld would no longer be associated with the primary pressure boundary, a defect in the weld could grow into the low allow steel RVCH and thereby impact the structural integrity of the remaining pressure boundary. Since a potential, or even detected, flaw in the J-groove weld can not be sized by currently available non-destructive examination techniques, it is assumed that the "as-left". condition of the remnant J-groove weld includes degraded or cracked weld material extending through the entire J-groove weld and Alloy 182 butter material.

Since it is known from analysis of the original Davis Besse Unit 1 CRDM reactor vessel head nozzle penetrations [3] that the hoop stress in the J-groove weld is greater than the axial stress at the same location, the preferential direction for cracking would be axial, or radial relative to the nozzle. Reference 3 also demonstrates that stresses tend to be higher on the uphill side of the nozzles than on the downhill side. It is postulated that a radial crack in the Alloy 182 weld metal would propagate by PWSCC, through the weld and butter, to the interface with the head material, where it is fully expected that such a crack would then blunt, or arrest, asdiscussed in Reference 4 for interfaces with low alloy steels. Since the height of the weld and butter along the bored surface is about 2" on the uphill side of the outermost CRDM nozzle, a radial crack depth extending from the corner of the weld to the low alloy steel head would be very deep. Although primary water stress corrosion cracking would not extend into the head, it is further postulated that a small fatigue initiated flaw forms in the low alloy steel head and combines with the stress corrosion crack in the weld to form a large radial flaw that would propagate into the head by fatigue crack growth under cyclic loading conditions. Linear-elastic (LEFM) and elastic-plastic (EPFM) fracture mechanics procedures are utilized to evaluate this worst case flaw in the original J-groove weld and butter.

Key features of the fracture mechanics analysis are:

" This analysis applies specifically to the CRDM nozzle penetrations in the Davis Besse Unit 1 reactor vessel closure head. A J-integral resistance curve is developed based on estimates of the Charpy V-notch upper-shelf energy for the DB-1 head plate material.

• Flaw growth is calculated for a 4 year period of operation, corresponding to 2 fuel cycles.

" Flaw acceptance is based on the available fracture toughness and ductile tearing resistance of the RVCH material considering the safety factors listed in Table 1-1.

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Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 1-1: Safety Factors for Flaw Acceptance Linear-Elastic Fracture Mechanics Operating Condition Evaluation Method Fracture Toughness / K, Normal/Upset Kia fracture toughness 4/10 = 3.16 Emergency/Faulted Kic fracture toughness '12 = 1.41 Elastic-Plastic Fracture Mechanics Operating Condition Evaluation Method Primary Secondary Normal/Upset J/T based flaw stability 3.0 1.5 Normal/Upset J0 .1 limited flaw extension 1.5 1.0 Emergency/Faulted J/T based flaw stability 1.5 1.0 Emergency/Faulted J 0.1 limited flaw extension 1.5 1.0 Page 9

Controlled Document A Document No. 32-9136508-001 AR EVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair

-TRIPLE POINT GR. B CL. 1 ERNiCrFe-7A ALLOY 52M Figure 1-1: ID Temper Bead Weld Repair Page 10

Controlled Document A

AR IE-VADocument No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 2.0 ANALYTICAL METHODOLOGY A radial flaw at the inside corner of non-radial head penetration is evaluated based on a combination of linear-elastic fracture mechanics (LEFM) and elastic-plastic fracture mechanics (EPFM), as outlined below.

1. Postulate a radial flaw in the J-groove weld, extending from the inside corner of the penetration to the interface between the butter and head, as shown in Figure 2-1 for the uphill side of the penetration. Previous analysis [5] has shown that even for large downhill welds, the controlling location is the uphill side of the penetration, due to higher stresses and the additional constraint provided by the acute angle between the material borders along the cladding and bore.

2. Develop a three-dimensional finite element crack model of the reactor vessel head in the vicinity of the outermost nozzle penetration, with crack tip elements along the interface between the Alloy 182 butter and the low alloy steel base metal. This crack model will be used to obtain stress intensity factors at various positions along the crack front for combined stresses due to J-groove welding, hydrostatic testing, nozzle removal, and transient loading conditions.

3. Develop a mapping procedure to transfer stresses from uncracked finite element stress analysis models (for residual and operational stresses) to the crack face of the crack model. This will enable stress intensity factors to be calculated for arbitrary stress distributions over the crack face utilizing the principle of superposition.

4. Calculate fatigue crack growth for cyclic loading conditions using combined residual and operational stresses from pressure and thermal loads. It is noted that the only effect of residual stress on fatigue crack growth is in the calculation of the R ratio, or Kmin/Kmax, which is the ratio of the minimum and maximum stress intensity, factors for a pair of stress states. Starting from the stress intensity factor calculated by the finite element crack model for the initial flaw size, stress intensity factors are updated for each increment of crack growth by the square root of the ratio of the flaw sizes over the increment.

5. Utilize the screening criteria of ASME Code Section XI, Appendix H to determine the failure mode and appropriate method of analysis (LEFM or EPFM) for flaws in ferritic materials, considering the applied stress, temperature, and material toughness. For LEFM flaw evaluations, compare the stress intensity factor at the final flaw size to the available fracture toughness, with appropriate safety factors, as, discussed in Section 2.2. When the material is more ductile and EPFM is the appropriate analysis method, evaluate flaw stability and crack driving force as described in Section 2.3.

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A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure 2-1: Postulated Radial Flaw on Uphill Side Page 12

Controlled Document A

AR vA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 2.1 Stress Intensity Factor Solution Stress intensity factors for corner flaws at a non-radiall nozzle penetration are best determined by finite element analysis using three-dimensional models with crack tip elements along the crack front.

Although loads can be applied to finite element crack models like any other structural model, the crack model was developed to serve as a flaw evaluation tool that could accept stresses from separate stress analyses. This strategy makes it possible, for example, to obtain pressure and thermal stresses from an independent thermal/structural analysis and then transfer these stresses to a crack model for flaw evaluations. Using the principle of superposition common to fracture mechanics analysis, the only stresses that need be considered for these flaw evaluations are the stresses on the crack face. A mapping procedure is developed to transfer stresses from a separate stress analysis to the crack face of the crack model.

2.1.1 Finite Element Crack Model A three-dimensional finite element model is developed for the reactor vessel head in the vicinity of the outermost nozzle penetration, by modeling a portion of the head, cladding, and butter with the ANSYS finite element computer program [6]. Since stresses increase with penetration angle, it is conservative to base the model on the outermost nozzle penetration. Details of the finite element crack models are presented in Appendix A.

The three-dimensional finite element model is first constructed to represent an unflawed non-radial nozzle penetration in the reactor vessel head using the ANSYS SOLID95 20-node structural element.

Elements along the crack front are then replaced by a sub-model of crack tip elements along the interface between the Alloy 182 butter and the low alloy steel base metal. These elements consist of 20-node isoparametric elements that are collapsed to form a wedge with the appropriate mid-side nodes shifted to quarter-point locations to simulate a singularity at the crack tip. The final crack model is shown in Figure 2-2.

Stress intensity factors are obtained using the ANSYS KCALC routine at 10 positions along each crack front, as indicated in Figure 2-2. Position 1 in located on the cladding surface, Position 2 at the cladding/base metal interface, and Position 10 is at the bored surface in the head.

2.1.2 Stress Mapping Residual and operational stresses, obtained from separate finite element models, are mapped onto the crack face of the finite element crack model shown in Figure 2-2 to calculate the individual contributions to the stress intensity factors. A set of ANSYS parametric design language instructions (macro) has been written based on the *MOPERMAP command to transfer stresses by nodal interpolation from a dissimilar finite element model (e.g., residual stresses) to the crack model. Stresses from an identical finite element model (e.g., operational stresses), are simply copied from the stress model to the crack model.

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A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure 2-2: Finite Element Crack Model Page 14

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 2.1.3 Crack Growth Considerations The fundamental expression for the crack tip stress intensity factor is K, = u Since the crack model is developed for a single flaw size, stress intensity factors are updated at each.

increment of crack growth by the square root of the flaw size; i.e.,

aj41 KI(ai~1 ) = K,(a) VIa, where a = flaw size i = increment of crack growth.

Since the stress intensity factor is directly proportionalto the magnitude of the stress and both residual and operating stresses decrease in the direction of crack growth, this procedure produces conservative estimates of stress intensity factor as the crack extends into the head and stresses diminish over the expanding crack face.

2.1.4 Plastic Zone Correction The Irwin plasticity correction is used to account for a moderate amount of yielding at the crack tip. For plane strain conditions, this correction is 1

671 (a) [ Ref. [7], Eqn. (2.63)]

where K,(a) = stress intensity factor based on the actual crack size, a Y = material yield strength.

A stress intensity factor, KI(ae), is then calculated for an effective crack size, ae =a+ry, based on the same scaling technique utilized for crack growth; i.e.,

a iPage 15

Controlled Document A

ARE VA- Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 2.2 Linear-Elastic Facture Mechanics Article IWB-3612 of Section XI [11] requires that the applied stress intensity factor, KI, at the final flaw size be less than the available fracture toughness at the crack tip temperature, with appropriate safety factors, as outlined below.

Normal and upset conditions: KI < Ka /'[1 where Kla is the fracture toughness based on crack arrest.

Emergency and faulted conditions: KI < Kic/.-r2 where K1c is the fracture toughness based on crack initiation.

2.3 Elastic-Plastic Facture Mechanics Elastic-plastic fracture mechanics (EPFM) will be used as alternative acceptance criteria when the flaw related failure mechanism is unstable ductile tearing. This type of failure falls between rapid, non-ductile crack extension and plastic collapse. Linear-elastic 'fracture mechanics (LEFM) would be used to assess the potential for non-ductile failure, whereas limit load analysis would be used to check for plastic collapse.

2.3.1 Screening Criteria Screening criteria for determining failure modes in ferritic materials may be found in Appendix H of Section Xl. Although Appendix H, Article H-4200 [11] contains specific rules for evaluating flaws in Class 1 ferritic piping, its screening criteria may be adapted to other ferritic components, such as the reactor vessel head, as follows:

Let, Kr' = Klapp I Kic Sr'= max I af Then the appropriate method of analysis is determined' by the following limits:

LEFM Regime: Kr' / Sr' - 1.8 EPFM Regime: 1.8 > Kr' / Sr' > 0.2 Limit Load Regime: 0.2 > Kr' / Sr' 2.3.2 Flaw Stability and Crack Driving Force Elastic-plastic fracture mechanics analysis will be performed using a J-integral/tearing modulus (J-T) diagram to evaluate flaw stability under ductile tearing, where J is either the applied (Japp) or the material (Jmat) J-integral, and T is the tearing modulus, defined as (E/Gf 2)(dJ/da). The crack driving force, as measured by Japp, is also checked against the J-R curve at a crack extension of 0.1 inch(J 0.1).

Consistent with industry practice for the evaluation of flaws in partial penetration welded nozzles, Page 16

Controlled Document A

ARE VA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair different safety factors will be utilized for primary and secondary loads. Flaw stability assessments for normal and upset conditions will consider a safety factor of 3 on the stress intensity factor due to primary (pressure) stresses and a safety factor of 1.5 for secondary (residual plus thermal) stresses.

The crack driving force will be calculated using safety. factors of 1.5 and 1 for primary and secondary stresses, respectively. For EPFM analysis of faulted conditions, safety factors of 1.5 and 1 will be used for flaw stability assessments and 1.5 and 1 for evaluations of crack driving force.

The general methodology for performing an EPFM analysis is outlined below.

Let E' = E/(1_-v2 )

Final flaw depth = a Total applied K, = Klaip K, due to pressure (primary) = Kip (from Appendix B)

K, due to residual plus thermal (secondary) = K1 js= Klapp - Kip Safety factor on primary loads = SFp Safety factor on secondary loads = SF*

For small scale yielding at the crack tip, a plastic zone correction is used to calculate an effective flaw depth based on ae = a + [1/(67r)] [ (K p + Kis) / oy 12, which is used to update the stress intensity factors based on K'l= K1 a and K',s ,s/ a "

Fa The applied J-integral is then calculated using the relationship Japp = (SFp*K'lp + SFs*K'is) 2/E'.

The final parameter needed to construct the J-T diagram is the tearing modulus. The applied tearing modulus, Tapp, is calculated by numerical differentiation for small increments of crack size (da) about the final crack size (a), according to E [Japp(a+da)-Japp(a-da)]

T Gf=o-- 2(da)

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Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Using the power law expression for the J-R curve, Jmat = C(ASa)m, the material tearing modulus, Tmat, can be expressed as Tmat = (E/f 2)Cm(Aa)m- 1.

Constructing the J-T diagram, Unstable Region Tapp ý Tmat Applied Instability Point Material Stable Region Tapp < Tmat T

flaw stability is demonstrated at an applied J-integral when the applied tearing modulus is less than the material tearing modulus. Alternately, the applied J-integral is less than the J-integral at the point of instability.

To complete the EPFM analysis, it must be shown that the applied J-integral is less than J 0.1, demonstrating that the crack driving force falls below the J-R curve at a crack extension of 0.1 inch.

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Controlled Document AR AVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 3.0 ASSUMPTIONS This section discusses assumptions and modeling simplifications applicable to the present evaluation of the DB-1 CRDM nozzle remnant flaw.

3.1 Unverified Assumptions There are no assumptions that must be verified before the present analysis can be used to support the CRDM nozzle IDTB repair at Davis Besse Unit 1.

3.2 Justified Assumptions The size of the J-groove weld prep and the thickness of the buttering are based on nominal dimensions. This is considered to be standard practice in stress analysis and fracture mechanics analysis. It is conservatively assumed that the postulated flaw extends through the entire J-groove weld and butter.

3.3 Modeling Simplifications The finite element computer models used to generate residual stresses and transient operational stresses do not include the ID temper bead repair weld. This is deemed to be an appropriate modeling simplification considering the very local effect of the repair weld on stresses in the J-groove weld.

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Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 4.0 DESIGN INPUTS This section provides basic input data needed to perform a fatigue crack growth analysis and a flaw evaluation of the final flaw size.

4.1 Materials 4.1.1 Mechanical and Thermal Properties Table 4-1, Table 4-2, and Table 4-3 list the temperatulre dependent values of modulus of elasticity (E),

Poisson's ratio (v), and coefficient of thermal expansion (aL) properties used in the finite element crack models. These properties are obtained from a previous stress analysis model of the Davis Besse CRDM nozzle and reactor vessel head [8]. Mechanical properties for the low alloy steel head are also provided in Table 4-1, where the flow stress is the average of the yield and ultimate strengths. The yield and ultimate strength values are obtained from Supplemental Requirements for SA-533 Manganese-Molybdenum-Nickel Alloy Steel Plates in the 1968 original construction code [9].

Component Material RV head SA-533 Grade B Class 1 [2]

Cladding Stainless steel (use Type 316 properties)

J-groove weld filler Alloy 182 [2] (use Alloy 600 properties for SB-167)

J-groove weld butter Alloy 182 [2] (use Alloy 600 properties for SB-1i67)

Table 4-1: Material Properties for Head Component Head Material SA-533 Grade B Class 1 Temperature E (106 psi) v cX (10-6 in./in./°F) cy (ksi) au (ksi) af (ksi) 70 29.00 0.29 7.06 50.00 80.00 65.00 100 29.00 0.29 7.06, 50.00 80.00 65.00 200 28.50 0.29 7.34 47.15 76.45 61.80 300 28.00 0.29 7.43 45.25 76.40 60.83 400 27.40 0.29 7.58 44.50 76.40 60.45 500 27.00 0.29 7.70; 43.20 76.40 59.80 600 26.40 0.29 7.83 42.00 76.40 59.20 700 25.30 0.29 7.94, 40.60 76.40 58.50 Page 20

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 4-2: Material Properties for Weld Metal Component Weld Butter and Weld Filler Material Use Alloy 600 (SB-167)

Temperature E (106 psi) v a (10-6 in./in./°F) 70 30.82 0.3 6.90 100 30.82 0.3 6.90 200 30.20 0.3 7.20 300 29.90 0.3 7.40 400 29.50 0.3 7.57 500 29.00 0.3 7.70 600 28.70 0.3 7.82 700 28.20 1 0.3 7.94 Table 4-3: Material Properties for Cladding Component Cladding Material Use Type 316:(16Cr-12Ni-2Mo) Stainless Steel Temperature E (106 psi) v a (10.6 in./in./°F) 70 28.14 0.3 8.54 100 28.14 0.3 8.54 200 27.60 0.3 8.76 300 27.00 0.3 8.97 400 26.50 0.3 9.21 500 25.80 0.3 9.42 600 25.30 0.3 9.60 700 24.80 0.3 9.76 Page 21

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 4.1.2 Reference Temperature Based on a highest measured RTNDT of { }, a value of { } OF will be used as a conservative estimate of the RTNDT for the SA-533, Grade B, Class 1 low alloy steel head material.

4.1.3 Fracture Toughness From Article A-4200 of Section XI [11], the lower bou Ind KIa fracture toughness for crack arrest can be expressed as Kia = 26.8 + 12.445 exp [ 0.0145 (T - RTNDT)],

where T is the crack tip temperature, RTNDT is the reference nil-ductility temperature of the material, Kia is in units of ksi4in, and T and RTNDT are in units of OF., In the present flaw evaluations, Kia is limited to a maximum value of 200 ksibin (upper-shelf fracture toughness). Using the above equation with an RTNDT of { } OF, Kla equals 200 ksi*/in at a crack tip temperat Ire of { } OF.

A higher measure of fracture toughness is provided by the K1c fracture toughness for crack initiation, approximated in Article A-4200 of Section XI [11] by Kic = 33.2 + 20.734 exp [ 0.02 (T - RTNDT) ].

4.1.4 J-integral Resistance Curve The J-integral resistance (J-R) curve, needed for the EPFM method of analysis, is obtained from the following power law expression for nuclear reactor pressure vessel steels [12],

JR = C(Aa)m, where the coefficient, C, and exponent, m, depend on the Charpy V-notch upper-shelf energy, CVN, and the flow stress, ao or af, as shown in Figure 4-1 and Figure 4-2.

An estimated value of the Charpy V-notch upper-shelf energy is available from a generic study of plate materials used in B&W fabricated reactor vessels [13]. This statistical analysis of {

} determined with a 95% confidence that at least 95% of the population exhibited upper-shelf energies exceeding a lower tolerance value of { } ft-lbs in the transverse (weak) direction.

Using the above referenced Charpy V-notch upper-shelf energy correlation for the J-integral resistance curve with a Charpy V-notch upper-shelf energy of { } ft-lbs, the coefficients of the power law are found to be:

c=

m={ }

Page 22

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 15 10 C

5 0

0.0 0.4 0.8 1.2 1.6 2.0 CVN/1oo F

Figure 4-1 : Correlation of Coefficient, C, of Power Law with Charpy V-Notch Upper Shelf Energy 0.7 0.6 0.5 0.4 m

0.3 0.2 0.1 0

0 2 4 6 8 10 12 14 16 x = C + 1.5,.--=-_,

Figure 4-2: Correlation of Exponent, m, of Power Law with Coefficient, C, and Flow Stress, o, Page 23

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 4.1.5 Fatigue Crack Growth Rate Flaw growth due to cyclic loading is calculated using the fatigue crack growth rate model from Article A-4300 of Section XI [11],

da )n dN where AKI is the stress intensity factor range in ks[i/i and da/dN is in inches/cycle. The crack growth rates for a surface flaw will be used for the evaluation' of the corner crack since it is assumed that the degraded condition of the J-groove weld and butter exposes the low alloy steel head material to the primary water environment.

The following equations from Section XI [11] are used to model fatigue crack growth.

AKI = Klmax - Klmin R = Klmin / Klmax 0*< R *0.25: AK1 < 17.74, n = 5.95 C, = 1.02x10-12 xS S= 1.0 AKI Ž17.74, n= 1.95 C= 1.01 x 10-7 S S= 1.0 0.25

• R < 0.65: AK1 < 17.74 [ (3.75R + 0.66) / (26.9R - 5.725) ]0.25, n = 5.95 C, = 1.02x10-12 xS S = 26'9R - 5.725 AKI _ 17.74 [ (3.75R + 0.06) (26.9R - 5.725) ]o.25, n = 1.95 C = 1.01 x 10-7 x S S = 3.75R + 0.06 0.65*< R < 1.0: AK1 < 12.04, n = 5.95 Co = 1.02x10-12 xS S = 11.76 AK1 > 12.04, n= 1.95 CS = 1.01X10-5XS S = 2.5 Page 24

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 4.2 Basic Geometry The reactor vessel head and original CRDM nozzle penetration are described by the following key dimensions:

Radius to base metal ={ }in. [14]

Head thickness (minimum) = { } in. [14]

Cladding thickness (nominal) = { } in. [15]

Butter thickness (nominal) = { } in. [16] or{

Penetration bore = { } in. [16]

Penetration angle at outermost nozzle = { } deg. [16]

Details of the CRDM nozzle penetration and J-groove'weld are provided in the description of the finite element crack model in Appendix C.

4.3 Operating Transients The most significant normal and upset condition transients for fatigue crack growth may be combined into a 'full-range' transient comprised of heatup to 100% power (HU), a Type B reactor trip (RT), and subsequent normal cooldown (CD). Full-range transients are associated with operating events that include a zero state of stress. The reactor coolant functional specification [17] provides pressure and temperature time-histories for these transients, and lists 240 design cycles for the heatup/cooldown transient and { } cycles for the Type B reactor trip.

The rod withdrawal accident (RWA) upset transient was also selected since it experiences a high reactor coolant pressure of { } psig. This is especially significant for EPFM flaw evaluations where primary pressure loads are subjected to higher safety factors than secondary thermal loads. Since it is not expected that a rod withdrawal accident will occur-during a four year period of operation, the RWA transient is not included in the calculation of fatigue crack growth, but it is addressed when evaluating the acceptability of the final flaw size. Transient 11 of the functional specification represents this design transient as an in-surge to the pressurizer which is based on the event that results in the greatest RCS pressure and temperature change. This event is initiated from 15% power and results in a 550 psi increase in RCS pressure and a 15 OF increase in temperature. The transient is of short duration, lasting approximately 20 to 30 seconds, producing only a minimal increase in head temperature. The functional specification transient bounds the expected change in the RCS pressure and temperature from the same event if initiated from full power conditions. As provided in Figure 15.2.2-1 of the DB-1 UFSAR [18], a rod withdrawal event from full power results in an increase of only 30 psi and 1.5 OF.

The functional specification also specifies one emergency condition transient, a stuck open turbine bypass valve, and two faulted condition transients, a steam line break and a loss of coolant accident.

Appendix F of the Section III stress analysis for the CRDM nozzle IDTB weld repair [19] concludes that the stresses resulting from the emergency and faulted condition transients are bounded by those for the reactor trip transient. And since the safety factors on. fracture toughness are higher for normal/upset conditions than for emergency/faulted conditions (Table 1-1), and the Kic fracture toughness for crack initiation is higher than the Ka fracture toughness for crack arrest (Section 4.1.3), it follows that the present flaw evaluations for normal/upset conditions also serve as a bounding analysis for emergency Page 25

Controlled Document A

ARE VA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair and faulted conditions. No further consideration of the emergency and faulted transients is therefore warranted.

4.4 Applied Stresses Two sources of applied stress are considered for the 'present flaw evaluations, residual stresses from welding and stresses that occur during normal operation.

4.4.1 Residual Stresses Residual stresses are obtained from a three-dimensional elastic-plastic finite element stress analysis performed by Dominion Engineering, Inc. [20]. Hoop stresses on the radial plane through the weld and butter are then mapped to the three-dimensional finite element crack model described in Section 2.1.1.

Hoop stresses are used since these stresses are perpendicular to the crack face and therefore open the crack.

The DEI analysis simulated welding of the J-groove buttering, a post-weld heat treatment, welding of the J-groove partial penetration weld at the outmost CRDM nozzle, hydrostatic testing, operation at steady state temperature and pressure conditions, return to zero load conditions, removal of the original nozzle (Time 11006), and a second application of steady state loads. It is known from previous analysis that stresses at the outermost CRDM nozzle location conservatively bound stresses at all other nozzle locations [3]. The residual stresses in the remnant J-groove weld and butter are obtained from the load step corresponding to Time 11006, prior to the return to operating conditions The DEI finite element model is shown in Figure 4-3, prior to removal of the CRDM nozzle. Figure 4-4 provides a closer view of the J-groove weld after the nozzle is removed.

4.4.2 Operational Stresses Operational stresses are obtained by linear-elastic stress analysis using the three-dimensional finite element crack model described in Section 2.1.1, but with displacements normal to the crack face constrained to zero. Hoop stresses on a radial plane through the weld and butter are then copied directly to the crack model to facilitate the calculation ,of stress intensity factors along the entire crack front. Stresses are developed for the combined heatup/reactor trip/cooldown and rod withdrawal transients discussed in Section 4.3 using the thermal and structural finite element models described in Appendix D.

Figure 4-5 illustrates the "uncracked" finite element model used to calculate nodal temperatures (transient thermal analysis) and stresses (static stress analysis). The thermal phase of the solution is driven by wetted surface loads developed from time-dependent bulk fluid temperatures and convective heat transfer (film) coefficients. The structural model is then loaded by internal pressure (surface load) and nodal temperatures (body force loads from the thermal solution) to determine stresses at various times, as listed in Table 4-4. The critical time points are selected only after calculating stress intensity factors for each set of stresses output from the stress analysis solution. This process serves to maximize the stress intensity factors used in the fatigue crack growth analysis and the final flaw evaluations. The time points selected for use in the subsequent fracture mechanics analyses are identified in Table 4-4 by alphanumeric symbols.

Page 26

A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure 4-3: DEI Finite Element Stress Model Page 27

A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure 4-4: DEI Finite Element Stress Model - Weld Region Page 28

Dowr K1 G(V A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure 4-5: Finite Element Stress Model for Operational Stresses Page 29

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 4-4: Transient Analysis Time Points for Operational Stresses L

Load Time Temp. Pressure Comment Step (hours) (F) (psig) I Combined Heatup/Reactor Trip/Cooldown SD 1 Zero stress state 2 End of heatup ramp 3 After heatup ramp 4 Steady state at 8% power 5 A End of power loading ramp (8%-100%)

6 After power loading ramp (8%-100%)

SS 7 _ Steady state at 100% power RT1 8 Reactor trip 9 Reactor trip RT2 10 Reactor trip 11 End of cooldown ramp Rod Withdrawal Accident RWA 2 Maximum pressure 3 i 4

• Symbols: SD = Shutdown SS = Steady State RT1 = Reactor Trip time 1 RT2 = Reactor Trip time 2 RWA = Rod Withdrawal Accident Page 30

Controlled Document A ,

VDocument No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 5.0 CALCULATIONS Propagation of a postulated initial flaw in the J-groove weld and butter is calculated to determine the final flaw size after a four year service interval. Flaw evaluations are then performed to assess the acceptability of the final flaw size.

5.1 Fatigue Crack Growth Although it is believed that a PWSCC flaw would be confined to the J-groove weld and butter, it is postulated that a fatigue flaw would initiate in the low alloy steel head, combine with the PWSCC flaw, and propagate farther into the head under cyclic loads. Fatigue crack growth is calculated from stress intensity factors derived from a finite element crack model using residual stresses from a DEI stress analysis [20] and operational stresses calculated herein. The actual flaw growth calculations are presented in Table 5-1, along with a comparison of the final stress intensity factor with the LEFM acceptance criteria for each of the five significant load :steps identified in Table 4-4. This table therefore serves several purposes; it determines the final flaw size at the end the designated service interval, it compares stress intensity factors at the final flaw size with LEFM acceptance criteria, and it serves as a means of identifying the controlling load steps for EPFM evaluation.

Crack growth is calculated for each heatup/cooldown cycle. Since the original design basis [17]

specifies 240 heatup/cooldown cycles over a 40 year period, the corresponding time increment is one-sixth of a year.

Stress intensity factors are provided in Table 5-1 for all locations along the postulated crack front, including the cladding. It is apparent from the stress intensity factors listed in these tables for the initial flaw sizes that the highest value in the low alloy steel head occurs at the bored surface.

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Controlled Document A

ARtEVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-1: Flaw Growth and LEFM Evaluation INPUT DATA Initial Flaw Size: Depth along bore, a, = 2.035 in.

Fracture Toughness: Reference temperature of head, RTndt = I I F Upper shelf toughness, UST = 200 ksi1in KIc = 33.2 + 20.734 exp [ 0.02 (T - RTndt)] < UST Kla = 26.8 + 12.445 exp [ 0.0145 (T - RTndt) ] < UST Stress Intensity Factors:

Condition* SD SS RT1 RT2 RWA Temperature 70 608 - 610 530 600 F Pressure 0 2155 2450 1720 2745 psig Sy 50.0 41.9 41.9 42.8 42.0 ksi KIc 58.5 200.0 200.0 200.0 200.0 ksi/in Kla 41.2 200.0 200.0 200.0 200.0 ksi'/in Crack Front Stress Intensity Factor, KI Position (psiin) (psiin) (psiin) (psiin) (psi'in)

Cladding Surface 1 72012 94317 99728 121749 113102 2 57085 80555 85683 103246 98142 3 51528 76707 81904 97080 94057 4 50744 77191 82454 95497 94199 5 51092 77988 83217 94302 94399 6 50355 76704 81732 90907 92098 7 50354 76451 81216 87459 90395 8 55409 84199 89223 94177 98404 9 58477 93779 99714 104872 110130 Bored Surface 10 61779 101946 108634 114318 120167

• Condition Description SD Time step 1 at 0 hr. of heatup/reactor trip/cooldown (shutdown w/ only residual stress)

SS Time step 7 at 10.000 hr. of heatup/reactor trip/cooldown (steady state at 100% power)

RT1 Time step 8 at 10.004 hr. of heatup/reactor trip/cooldown (during reactor trip)

RT2 Time step 10 at 10.141 hr. of heatup/reactor trip/cooldown (during reactor trip)

RWA Time step 2 at 0.0044 hr. into rod withdrawal accident (high pressure condition)

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Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-1: Flaw Growth and LEFM Evaluation (Cont'd)

FATIGUE CRACK GROWTH Transient

Description:

240 cycles over 40 years AN = 6 cycles/year Crack Front Position 10 Operating RT2 SD SS RT1 RWA Cycle Time a KI(a)max KI(a)min AKI Aa Kl(a) Kl(a) KI(a)

(end of yr.) (in.) (ksNin) (ksi4in) (ksihin) (in (ksi~in) (ksi~in) (ksilin) 0 0.000 2.03500 114.318 61.779 52.539 101.946 108.634 120.167 1 0.167 114.398 61.822 52.576 102.018 108.710 120.252 2 0.333 114.479 61.866 52.613 102.089 108.787 120.336 3 0.500 114.559 61.909 52.650 102.161 108.863 120.421 4 0.667 114.640 61.953 52.687 102.233 108.940 120.505 5 0.833 114.720 61.997 52.724 102.305 109.016 120.590 6 1.000 114.801 62.040 52.761 102.377 109.093 120.675 7 1.167 114.882 62.084 52.798 102.449 109.170 120.760 8 1.333 114.963 62.127 52.835 102.521 109.247 120.845 9 1.500 115.043 62.171 52.872 102.593 109.323 120.930 10 1.667 115.124 62.215 52.910 102.665 109.400 121.015 11 1.833 115.205 62.258 52.947 102.737 109.477 121.100 12 2.000 115.286 62.302 52.984 102.809 109.554 121.185 13 2.167 115.367 62.346 53.021 102.882 109.631 121.270 14 2.333 115.448 62.390 53.059 102.954 109.708 121.355 15 2.500 115.530 62.434 53.096 103.026 109.785 121.441 16 2.667 115.611 62.478 53.133 103.099 109.862 121.526 17 2.833 115.692 62.522 53.170 103.171 109.940 121.611 18 3.000 115.773 62.565 53.208 103.244 110.017 121.697 19 3.167 115.855 62.609 53.245 103.316 110.094 121.782 20 3.333 115.936 62.653 53.283 103.389 110.172 121.868 21 3.500 116.018 62.697 53.320 103.462 110.249 121.953 22 3.667 116.099 62.742 53.358 103.534 110.327 122.039 23 3.833 116.181 62.786 53.395 103.607 110.404 122.125 24 4.000 , 1 116.262 62.830 53.433 103.680 110.482 122.211 Page 33

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-1: Flaw Growth and LEFM Evaluation (Cont'd)

I LEFM FRACTURE TOUGHNESS MARGINS Period of Operation: Time = 4 years Flaw Size: a= { in.

Loading Conditions SD SS RT1 RT2 RWA Fracture Toughness, KIc 58.5 200.0 200.0 200.0 200.0 ksiq1in Fracture Toughness, Kla 41.2 200.0 200.0 200.0 200.0 ksi'in Position 10 Kl(a) 62.830 103.680 110.482 116.262 122.211 ksi'in a, 2.1886 2.4298 2.4744 2.4955 2.5540 in.

Kl(ae) 64.068 111.398 119.789 126.594 134.621 ksilin Margin = Klc / Kl(a.) n/a n/a n/a n/a n/a Margin = Kla / Kl(ae) 0.64 1.80 1.67 1.58 1.49 where: ae = a + 1/(6ir) [KI(a)/Sy]2 Kl(ae) = Kl(a)*U(a/a)

Page 34

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 5.2 LEFM Flaw Evaluations The results of the linear-elastic fracture mechanics flaw evaluations are summarized below for the final size of the postulated flaw after fatigue crack growth.

Flaw Size Initial flaw size, ai = 2.035 in.

Final flaw size after 4 years, af = { } in:

Flaw growth, Aa = { } in.

Controllinq Transients Shutdown Heatup/Cooldown Rod Withdrawal w/ Reactor Trip (RT2) Accident Condition Low Temperature Normal Upset Temperature, T = 70 OF { }OF { }OF Fracture toughness, Kia = 41.2 ksihin 200.0 ksi'lin 200.0 ksi'lin Final stress intensity factor, KI(af) = 62.8 ksi-/in 116.3 ksi'/in 122.2 ksi'lin Effective flaw size, ae = 2.189 in. 2.500 in. 2.554 in.

Effective stress intensity factor, KI(ae) = 64.1 ksiin 126.6 ksi',in 134.6 ksi!in Fracture toughness margin (> 3.16), Kia/ KI(ae) = 0.64 1.58 1.49 Since the controlling fracture toughness margins are less than the Code required minimums, EPFM flaw evaluations will be performed to account for the ductile behavior of the low alloy steel during stable crack growth.

Page 35

Controlled Document A Document No. 32-9136508-001 AR EVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 5.3 EPFM Flaw Evaluations The elastic-plastic fracture mechanics procedure described in Section 2.3 is used to evaluate the final size of the postulated flaw after fatigue crack growth.

Flaw Size Initial flaw size, ai = 2.035 in.

Final flaw size after 4 years, af={ }in.

Controllinq Transients Shutdown Heatup/Cooldown Rod Withdrawal w/ Reactor Trip (RT2) Accident SCREENING PROCEDURE T = 70 OF { }OF { }OF E = 29000 ksi 26820 ksi 26400 ksi v = 0.3 0.3 0.3 E'= E/(1-v 2 ) = '31860 ksi 29470 ksi 29010 ksi CTY = 50.0 ksi 42.8 ksi 42.0 ksi cyu = 80.0 ksi 76.4 ksi 76.4 ksi caf = 65.0 ksi 59.6 ksi 59.2 ksi Crack initiation toughness, KIc = 58.5 ksi/in 200.0 ksilin 200.0 ksirin Total applied K1, KI(ae) = 64.1 ksi/in 126.6 ksi*in 134.6 ksiin Then, Kr' = KI(ae) / KIc = 1.095 0.633 0.673 From finite element stress analysis, the maximum crack face stresses due to residual stress, pressure, and thermal gradients are Cyrnax = 66.4 ksi 110.9 ksi 114.5 ksi Then, S'= Umax / CTf= 1.022 1.860 1.934 Screening ratio, Kr' / Sr' = 1.072 0.340 0.348 The analysis is therefore in the EPFM regime (1.8 > Kr' / Sr' Ž>0.2) for both loading conditions.

EPFM ANALYSIS Total applied K1 , KI(a) = 62.8 ksi'Iin 116.3 ksi'/in 122.2 ksi4in K, primary (pressure from Appendix E), K1p(a) = 0.0 ksi'/in 39.8 ksiin 63.6 ksiJin K, secondary (residual plus thermal), KI,(a) = 62.8 ksi[/in 76.4 ksiqJin 58.6 ksi'lin Multiplying by 4(ae/a), K'jp(a) = 0.0 ksi[in 43.4 ksiqin 70.1 ksihin K'Is(a) = 64.1 ksi-lin 83.2 ksi*/in 64.6 ksi'/in Page 36

Controlled Document A

ARE VA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-2, Table 5-3, and Table 5-4 develop all the data necessary to construct J-T diagrams for the controlling operating conditions. The J-T diagrams are presented in Figure 5-1, Figure 5-2, and Figure 5-3.

For shutdown conditions, Table 5-2 shows for an applied J-integral of 0.290 kips/in, corresponding to safety factors of 3 and 1.5, the applied tearing modulus, 0.945, is less than the material tearing modulus, 318.0, indicating flaw stability. Alternately, the applied J-integral is less than the J-integral, 3.411 kips/in, at the point of instability. For safety factors of 1.5 and 1, the applied J-integral of 0.129 kips/in is less than the J0 .1 value of 1.350 kips/in, demonstrating that the crack driving force falls below the J-R curve at a crack extension of 0.1 inch.

For the heatup/cooldown transient with reactor trip, Table 5-3 shows for an applied J-integral of 2.206 kips/in, corresponding to safety factors of 3 and 1.5, the applied tearing modulus, 7.908, is less than the material tearing modulus, 22.15, indicating flaw stability. Alternately, the applied J-integral is less than the J-integral, 3.398 kips/in, at the point of instability. For safety factors of 1.5 and 1, the applied J-integral of 0.746 kips/in is less than the J 0.1 value of 1.363 kips/in, demonstrating that the crack driving force falls below the J-R curve at a crack extension of 0.1 inch.

For rod withdrawal accident conditions, Table 5-4 shows for an applied J-integral of 3.249 kips/in, corresponding to safety factors of 3 and 1.5, the applied tearing modulus, 11.63, is less than the material tearing modulus, 12.93, indicating flaw stability. Alternately, the applied J-integral is less than the J-integral, 3.397 kips/in, at the point of instability. For safety factors of 1.5 and 1, the applied J-integral of 0.992 kips/in is less than the J 0.1 value of 1.364 kips/in, demonstrating that the crack driving force falls below the J-R curve at a crack extension of 0.1 inch.

Page 37

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-2: EPFM Evaluation for Shutdown Conditions C:{

EPFM Equations: Jmat =

Tmat =

C(Aa) m (E/af 2)*CM (Aa)m-l 2

M =

}

Japp = (SFP*K'lp+SFs*K' 1 s) /E' 2

Tapp = (E/af )*(dJapp/da)

Ductile Crack Growth Stability Criterion: Tapp < Tmat At instability: Tapp =Tmat Safety Factors SF*K'Ip SF*K'Is Japp Tapp Stable?

Primary Secondary (ksi'/in) (ksi*iin) (kips/in) 1.00 1.00 0.000 64.068 0.129 0.420 Yes 2.00 2.00 0.000 128.136 0.515 1.681 Yes 3.00 1.50 0.000 96.102 0.290 0.945 Yes 5.00 5.00 0.000 320.339 3.221 10.503 Yes 7.00 7.00 0.000 448.475 6.313 20.587 No Iterate on safety factor until Tapp = Trmat to determine Jinstability:

Jinstability Tapp Tmat 5.1454 5.1454 0.000 329.655 3.411 11.123 11.123 at Jmat = 0.290 kips/in, Tmat 317.951 Applied J-Integral Criterion: Japp < J0.1 where, J0.1 = Jmat at Aa = 0.1 in.

Safety Factors SF*K'jp SF-K',5 Japp JO.1 OK?

Primary Secondary (ksi'/in) (ksi~in) (kips/in) (kips/in) 1.50 1.00 0.000 64.068 0.129 1.350 Yes Page 38

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-3: EPFM Evaluation for HeatuplCooldown with Reactor Trip EPFM Equations: Jmat = C(Aa) m Tmat = (E/Cif2

)*Cm(Aa)m-l C=

Japp = (SFp*K'Ip+SFs*K'Is) 2/E' 2

Tapp = (E/c )*(dJa~pda)

Ductile Crack Growth Stability Criterion: Tapp Tmat Tapp =Tmat At instability:

Safety Factors SF*K'jp SF*K'js Japp Tapp Stable?

Primary Secondary (ksNin) (ksNin) (kips/in) 1.00 1.00 43.391 83.204 0.544 1.949 Yes 2.00 1.00 86.782 83.204 0.980 3.515 Yes 3.00 1.50 130.172 124.806 2.206 7.908 Yes 5.00 1.00 216.954 83.204 3.057 10.959 Yes 7.00 1.00 303.736 83.204 5.080 18.212 No Iterate on safety factor until Tapp = Tmat to determine Jnstability:

Jinstability Tapp Tmat 2.4998 2.4998 108.468 207.992 3.398 12.182 12.182 at Jmat = 2.206 kips/in, Tmat = 22.150 Applied J-Integral Criterion: Japp < J0.1 where, J0.1 = Jmat at Aa = 0.1 in.

Safety Factors SF*K'jp SF-K 15 Jp Jo. 1 OK?

Primary Secondary (ksi'lin) (kips/in) 1.50 1.00 65.086 83.204 0.746 1.363 Yes Page 39

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table 5-4: EPFM Evaluation for Rod Withdrawal Accident EPFM Equations: Jmat =

Tmat =

C(Aa) m (E/-f 2)*Cm (Aa)m'l

}

Japp = (SFP*K'lp+SFs*K'is) 2/E' Tapp = (E/(Yf2 )*(dJapp/da)

Ductile Crack Growth Stability Criterion: Tapp < Tmat At instability: Tapp = Tmat Safety Factors SF*K'jp SF*K'ls Japp Tapp Stable?

Primary Secondary (ksiin) (ksiin) (kips/in) 1.00 1.00 70.055 64.566 0.625 2.236 Yes 2.00 1.00 140.110 64.566 1.444 5.168 Yes 3.00 1.50 210.165 96.849 3.249 11.628 Yes 5.00 1.00 350.275 64.566 5.932 21.231 No 7.00. 1.00 490.384 64.566 10.616 37.993 No Iterate on safety factor until Tapp = Tmat to determine Jinstability:

Jinstability Tapp Tmat 2.3320 2.3320 163.367 150.567 3.397 12.158 12.158 at Jmat = 3.249 kips/in, Tmat 12.933 Applied J-Integral Criterion: Japp < J0.1 where, Jo.1 = Jmat at Aa = 0.1 in.

Safety Factors SF*K'ip SF-K-Is Japp JO.1 OK?

Primary Secondary (ksi'Iin) (ksi'in) (kips/in) (kips/in) 1.50 1.00 105.082 64.566 0.992 1.364 Yes Page 40

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 8

7 6

5 Cý

.2-U) a, 3

2 1

0 0 5 10 15 20 25 30 35 40 45 50 Tearing Modulus Figure 5-1: J-T Diagram for Shutdown Conditions Page 41

Controlled Document A. Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 8

7 6

5 3

2 1

0 0 5 10 15 20 25 30 35 40 45 50 Tearing Modulus Figure 5-2: J-T Diagram for Heatup/Cooldown with Reactor Trip Page 42

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 8

7 6

5 F

• 4 3

2 0

0 5 10 15 20 25 30 35 40 45 50 Tearing Modulus Figure 5-3: J-T Diagram for Rod Withdrawal Accident Page 43

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair 1

6.0

SUMMARY

OF RESULTS AND CONCLUSIONS Elastic-plastic fracture mechanics has been used to evaluate a postulated radial flaw in the J-groove weld and butter of an outermost CRDM nozzle reactor vessel head penetration. The final flaw size was determined by linear elastic fracture mechanics for 4 years of fatigue crack growth.

6.1 Summary of Results Flaw Size Initial flaw size, ai = 2.035 in.'

Final flaw size after 4 years, af= { } in.

Controlling Transients Shutdown Heatup/Cooldown Rod Withdrawal w/ Reactor Trip Accident Temperature, T= 70 OF { }OF { }OF Safety factors (primary/secondary), SF= 3/1.51 3/1.5 3/1.5 Material tearing modulus, Tmat= 318.0 22.15 12.93 Applied tearing modulus (< Tmat) Tapp = 0.945 7.908 11.63 Safety factors (primary/secondary), SF= 1.5/1 1.5/1 1.5/1 Material J-integral, J0.1= 1.350 kips/in 1.363 kips/in 1.364 kips/in Applied J-integral (< J 0.1) Japp = 0.129 kips/in 0.746 kips/in 0.992 kips/in 6.2 Conclusion Based on a combination of linear elastic and elastic plastic fracture mechanics analysis of a postulated remaining flaw in the original Alloy 182 J-groove weld and butter material, a Davis Besse Unit 1 CRDM nozzle is considered to be acceptable for at least 4 years of operation following an IDTB weld repair.

Page 44

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair

7.0 REFERENCES

1. AREVA NP Drawing 02-9134305-002, "Davis Besse CRDM Nozzle ID Temper Bead Weld Repair."

2. AREVA NP Document 08-9134304-000, "Davisý Besse RVCH CRDM Penetration Modification,"

March 2010.

3. AREVA NP Document 38-1288564-00, "Calculation Number C-3206-00-1, Rev. 0, Davis Besse CRDM Stress Analysis," December 2001.

4. AREVA NP Document 51-5012047-00, "Stress Corrosion Cracking of Low Alloy Steel," March 2001.

5. AREVA NP Document 32-9066059-000, "Watts Bar CRDM Nozzle IDTB J-Groove Weld Analysis," December 2007.

6. ANSYS Finite Element Computer Code, Version 10.0, ANSYS Inc., Canonsburg, PA.

7. T.L. Anderson, Fracture Mechanics: Fundamentals and Applications, CRC Press, 1991.

8. AREVA NP Document 32-5011864-07, "CRDMH Connection 3D FE Model," March 2001.

9. ASME Boiler and Pressure Vessel Code,Section II, Material Specifications: Part A - Ferrous, 1965 Edition with Summer 1968 Addendum.

10. BAW-10046A, Rev. 2, "Methods of Compliance With Fracture Toughness and Operational Requirements of 10 CFR 50, Appendix G," B&W Owners Group Materials Committee Topical Report, June 1986.

11. ASME Boiler and Pressure Vessel Code,Section XI, Rules for Inservice Inspection of Nuclear Power Plant Components, 1995 Edition with Addenda through 1996.

12. NUREG-0744, Vol. 2, Rev. 1, "Resolution of the Task A-11 Reactor Vessel Materials Toughness Safety Issue," Appendix D, Materials Toughness Properties, Division of Safety Technology, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, October 1982.

13. AREVA NP Document 77-2313-006 (BAW-2313, Revision 6), "B&W Fabricated Reactor Vessel Materials and Surveillance Data Information," AREVA NP Inc., November 2008.

14. AREVA NP Drawing 02-142178E-05, "Closure Head Center Disc." (DB-1 Midland Head)

15. AREVA NP Drawing 02-154613E-08, "Arrangement Reactor Vessel Longitudinal Section." (DB-1 Midland Head)

Page 45

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair

16. AREVA NP Drawing 02-142179E-10, "Closure Head Sub-Assembly." (DB-1 Midland Head)

17. AREVA NP Document 18-1149327-003, "Functional Specification for Reactor Coolant System for Davis-Besse," July 2008.

18. Davis-Besse Nuclear Power Station No. 1 Updated Safety Analysis Report, Revision 26, June 2008.

19. AREVA NP Document 32-5012424-12, "CRDM Temper Bead Bore Weld Analysis," April 2004.

20. AREVA NP Document 32-9134665-000, "DEI I4esidual Stress Analysis for DB-1 CRDM Nozzle IDTB Repair," DEl Calc. No. C-8616-00-01, Rev. 0, Davis Besse CRDM Nozzle Welding Residual Stress Analysis, April 2010.

• Reference 18 is not retrievable from the AREVA NP Records Management system but are referenced here in accordance with AREVA NP Procedure 0402-01, Attachment 8. This customer reference is a valid source of design input as authorized by the Project Manager signature on page 2. 1 Page 46

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld F4law Evaluation for IDTB Repair APPENDIX A: VERIFICATION OF COMPUTER CODE ANSYS The ANSYS finite element computer program [6] is verified for use in the present flaw evaluation by executing three test cases from the ANSYS set of verification problems that utilize the SOLID90 thermal and SOLID95 structural 20-node 3-D solid elements. Test case VM161 determines heat flow in an insulated pipe. Test case VM148 analyzes a cantilevered, parabolic beam subjected to a static bending load. Test case VM143 calculates a stress intensity factor for a crack in a plate. All three test cases executed properly, as demonstrated below.

Verification Problem VM161 Thermal Analysis of an Insulated Pipe File: vm161.vrt VM161 RESULTS COMPARISON Surface Heat Flow Rate TARGET I ANSYS I RATIO q (BTU/hr) 362.0 362.0 1.000 Verification Problem VM148 Bending of a Parabolic Beam File: vm148.vrt VM148 RESULTS COMPARISON End Displacement TARGET I ANSYS I RATIO Y Deflection (in.) -0.01067 -0.01062 0.995 Verification Problem VM143 Fracture Mechanics Analysis of a Crack in a Plate File: vm143.vrt VM143 RESULTS COMPARISON Stress Intensity Factor by Displacement Extrapolation I TARGET I ANSYS I RATIO 3-D ANALYSIS 1.0249 1.0620 1.036 Page A-1

Controlled Document A Document No. 32-9136508-001 AREvA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair APPENDIX B: COMPUTER FILES IN COLDSTOR i

The computer files listed below, which remain unchanged from those listed in document 32-9134664-000, are stored in the AREVA NP COLDStor repository in the directory "\cold\41304\32-9134664-000\official".

ANSYS Models File Name Description Modified date Installed Date

!Date Date UphillCrackModel.db Crack model for uphill J-groove weld 03-19-10 04-12-10 UphillUnCrackModel.db Model for calculating operating stresses 03-20-10 04-12-10 MatlAndMesh.dat Material data for thermal and stress analysis 04-04-10 04-12-10 ANSYS Thermal Analysis File Name Description Modified Installed Date Date HURX8BThermal.dat Input file for HU/RT/CD thermal analysis 04-04-10 04-12-10 HURX8BThermal.out Output file for HU/RT/CD thermal analysis 04-05-10 04-12-10 RWAThermal.dat Input file for RWA thermal analysis 04-04-10 04-12-10 RWAThermal.out Output file for RWA thermal analysis 04-05-10 04-12-10 ANSYS Stress Analysis File Name Description Modified Installed Date Date HURX8BStress.dat Input file for HU/RT/CD stress analysis 04-04-10 04-12-10 HURX8BStress.out Output file for HU/RT/CD stress analysis 04-04-10 04-12-10 RWAStress.dat Input file for RWA stress analysis 04-04-10 04-12-10 RWAStress.out Output file for RWA stress analysis 04-05-10 04-12-10 ANSYS Macros for Transferring Stresses to Crack Model File Name Description Modified Installed Date Date FormatStresses_Driver.mac Driver to get residual stresses 03-28-10 04-12-10 FormatStresses.mac Macro to get residual stresses 03-28-10 04-12-10 Page B-1

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Modified Installed File Name Description Date Date GetStressesDriver.mac Driver to get operating stresses 04-05-10 04-12-10 Get_Stresses.mac Macro to get operating -stresses 04-05-10 04-12-10 ANSYS Analysis to Calculate Stress Intensity Factors (SIF)

File Name Description Modified Installed Date Date UphillCrackPressure.inp Input file for pressure loading 03-23-10 04-12-10 Press_Up.output Output file for pressure loading 04-07-10 04-12-10 GetRESIlSIFs.mac Macro to get SIFs for residual stresses 04-08-10 04-12-10 GetHUCDSIFs.mac Macro to get SIFs for HU/RT/CD stresses 04-05-10 04-12-10 GetRWASIFs.mac Macro to get SIFs for RWA stresses 04-05-10 04-12-10 MapStresses_Up.mac Macro to map stresses from uncracked model 03-24-10 04-12-10 to crack model PrtKlup.mac Macro to write SIFs to output file 03-24-10 04-12-10 RESIu.output Output file for residual SIFs 04-08-10 04-12-10 HUCDul.output Output file for HU/RT/CD SIFs (load step 1) 04-05-10 04-12-10 HUCDu2.output Output file for HU/RT/CD SIFs (load step 2) 04-05-10 04-12-10 HUCDu3.output Output file for HU/RT/CD SIFs (load step 3) 04-05-10 04-12-10 HUCDu4.output Output file for HU/RT/CD SIFs (load step 4) 04-05-10 04-12-10 HUCDu5.output Output file for HU/RT/CD SIFs (load step 5) 04-05-10 04-12-10 HUCDu6.output Output file for HU/RT/CD SIFs (load step 6) 04-05-10 04-12-10 HUCDu7.output Output file for HU/RT/CD SIFs (load step 7) 04-05-10 04-12-10 HUCDu8.output Output file for HU/RT/CD SIFs (load step 8) 04-05-10 04-12-10 HUCDu9.output Output file for HU/RT/CD SIFs (load step 9) 04-05-10 04-12-10 HUCDulO.output Output file for HU/RT/CD SIFs (load step 10) 04-05-10 04-12-10 HUCDul 1 .output Output file for HU/RT/CD SIFs (load step 11) 04-05-10 04-12-10 RWAul.output Output file for RWA SIFs (load step 1) 04-05-10 04-12-10 RWAu2.output Output file for RWA SIFs (load step 2) 04-05-10 04-12-10 RWAu3.output Output file for RWA SIFs (load step 3) 04-05-10 04-12-10 RWAu4.output Output file for RWA SIFs (load step 4) 04-05-10 04-12-10 Page B-2

Controlled Document A Document No. 32-9136508-001 AR EVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair ANSYS Verification Modified Installed File Name Description MoDife nale Date Date vml61 .vrt Verification problem for thermal analysis 04-07-10 04-12-10 vm148.vrt Verification problem for stress analysis 04-07-10 04-12-10 vm143.vrt Verification problem for stress intensity factor 04-07-10 04-12-10 Page B-3

Controlled Document A

AR EVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair APPENDIX C: FINITE ELEMENT CRACK MODEL C.1 Introduction A non-radial partial penetration nozzle in a spherically shaped pressure vessel presents a challenging set of geometric constraints for both stress analysis and fracture mechanics analysis of flaws, especially in the J-groove weld. Since there are no closed-form solutions available to calculate stress intensity factors for such flaws, a three-dimensional finite element crack model is developed in this appendix for use in evaluating "J-shaped" flaws in the area of the partial penetration attachment weld.

The three-dimensional finite element model is constructed using crack tip elements along the entire J-shaped crack front, extending from the inside surface of the cladding to the bored surface of the penetration. An uncracked model of the nozzle, J-groove weld and butter, and a portion of the reactor vessel head and cladding is first created using the ANSYS finite element computer program [6]. After removing a block of elements around the crack front and inserting a sub-model of crack tip elements, stress intensity factors can be obtained via the program's KCALC routine. The crack tip sub-model consists of 20-node isoparametric elements that are collapsed to form wedges, with the appropriate mid-side nodes shifted to quarter-point locations to create a 1/r singularity in strain at the crack tip.

Page C-1

Co--',, I -_6rnn A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair C.2 Base Finite Element Model A three-dimensional finite element model is constructed to represent an uncracked non-radial nozzle penetration in a hemi-spherical shaped head. This model utilizes the ANSYS SOLID95 3-D 20-node structural solid element, exclusively, so that a portion of the model can be readily removed and replaced with a crack tip sub-model.

C.2.1 Geometry As shown in Figure C-1, the model is a 180-degree segment of the head, cladding, weld butter, and J-groove weld.

Figure C-1: Overall Model of Reactor Vessel Head Penetration Page C-2

Controlled Document

'A Document No. 32-9136508-001

.AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Key dimensions are:

Radius to base metal in. [14]

Head thickness (minimum) (( in. [14]

Cladding thickness (nominal) in. [15]

Butter thickness (nominal) { in. [16] or { }

Hole diameter (original) { in. [16] (near{ } after machining [1])

J-groove weld center diameter { in. [16]

J-groove weld angle { } deg. [16]

Basic J-groove radius { in. [16]

Basic J-groove height { in. [16]{ }"

Additional height to base metal (nom.) { in. [16] or { }

Horizontal distance to outermost nozzle { } in. [16]

Penetration angle at outermost nozzle { } deg.

C.2.2 Materials The material designations of the various components of the model are:

Component Material RV head SA-533 Grade B Class 1 [2]

Cladding Stainless steel:(use Type 316 properties)

J-groove weld filler Alloy 182 [2] (use Alloy 600 properties for SB-167)

J-groove weld butter Alloy 182 [2] (use Alloy 600 properties for SB-167)

The mechanical and thermal properties for these materials are provided in Section 4.1.1.

C.2.3 Boundary Conditions The model includes a 180-degree segment of the weld and adjacent portions of the head. The vertical plane containing the vertical axes of the reactor vessel and the outermost penetration forms a plane of symmetry for the model. The displacements normal to this plane of symmetry are fixed (in the global Z-direction). Displacement constraints are also applied to the outer peripheral boundary of the spherical segment to simulate a state of membrane stress. By specifying meridional displacements to be zero in a spherical coordinate system, the head can only displace along a spherical radius parallel to this boundary.

C.3 Finite Element Crack Models The three-dimensional finite element crack model is developed by removing a portion of the head and butter and inserting a sub-model of crack tip elements, as illustrated in Figure C-2. Displacement constraints are also removed along the plane of symmetry for nodes on the crack face. Figure C-3 shows the final crack model used to analyze a postulated flaw in the J-groove weld and butter.

Page C-3

A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure C-2: Development of Crack Model Figure C-3: Final Finite Element Crack Model Page C-4

(",onrolld Dc.",

Se*

A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair APPENDIX D: FINITE ELEMENT STRESS MODEL A three-dimensional linear-elastic finite element model is developed for use in obtaining operational stresses from transient loading conditions. The origin of this model is the uncracked stress model described in Section C.2, prior to transformation to a crack model. The ANSYS SOLID95 3-D 20-node structural solid elements of the stress model are converted to SOLID90 3-D 20-node thermal solid elements to create a thermal model for use in transient analysis to calculate nodal temperatures.

Three heat transfer regions are defined for applying thermal loads to the model in the form of time-dependent bulk fluid temperatures and convective heat transfer coefficients (HTC). Figure D-1 identifies these regions at the inside surface of the cladding, the bored surface of the head at the location of the nozzle, and the outside surface of the head. Table D-1 lists the bulk fluid temperatures and heat transfer coefficients for the heatup/reactor trip/cooldown full-range transient used in the present flaw evaluations. Table D-2 provides similar data for the rod withdrawal accident transient. Temperature-time history plots are presented in Figure D-2 and Figure D-3 for both transients.

Inside Surface of Bore Insulation/

Air

(:Ambient Outside Surface of Head Figure D-1: Heat Transfer Regions of Thermal Model Page D-1

Controlled Document A

AREVA Document No. 32-9136508-001 AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table D-1: Heatup/Reactor Trip/Cooldown Transient Definition

References:

Section III Stress Analysis [19] and RCS Functional Specification [17]

Load Inside Outside Inside Cladding Inside Bore Outside Head Step Time Temp. Temp. HTC 2 HTC HTC Comment (hr.) (OF) (OF) (Btu/hr/in 2 -OF) (Btu/hr/in2 -OF) (Btu/hr/in 2 -°F) 1 f 2

3 heatup 4

5 II 6 I SS at 8% power k7 'power increase 8 ____ SS at 100% power 10 11 12 _ __ reactor trip 13 14 15 16 17 cooldown 18 Table D-2: Rod Withdrawal Accident Transient Definition

References:

Section III Stress Analysis [19] and RCS Functional Specification [17]

Load Inside Outside Inside Cladding Inside Bore Outside Head Step Time Temp. Temp. HTC HTC HTC Comment (hr.) (F) (Btu/hr/in 2-°F) (Btu/hr/in 2-°F) (Btu/hr/in 2-°F _

1 2

3 4

5 7

8 9

Page D-2

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Figure D-2: Heatup/Reactor Trip/Cooldown Temperature-Time History

[

j Figure D-3: Rod Withdrawal Accident Temperature-Time History Page D-3

Controlled Document A Document No. 32-9136508-001 ARE VA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair APPENDIX E: STRESS INTENSITY FACTOR DUE TO PRESSURE The elastic-plastic fracture flaw evaluations of Section 5.3 utilize different safety factors, for primary (pressure) and secondary stress (residual and thermal) intensity factors. In order to isolate the pressure term, K1p, stress intensity factors are developed for an arbitrary pressure load of 2500 psig at 600 OF.

Table E-1 presents stress intensity factors at the ten crack front positions defined in Figure 2-2. Since these values were determined for the initial crack size,;they are adjusted by the square root of the crack size, considering the final crack size after four years of crack growth, in the same fashion as described in Section 2.1.3.

The Kip pressure terms used in the EPFM flaw evaluations of Section 5.3 are derived below.

Let, K1P(a,P) = Kj(ao0,Po) aPpo a

Temperature, T = 600 OF Pressure, Po = 2500 psig Initial flaw size, a, = 2.035 in.

From Table E-1, Klp(ao,Po) = 56.952 ksi',in Controllinq Transients Shutdown Heatup/Cooldown Rod Withdrawal w/ Reactor Trip (RT2) Accident Temperature, T = 70 OF { }OF { }OF Pressure, P = 0 psig { } psig { }psig Final flaw size, a = 2.1048 in. 2.1048 in. 2.1048 in.

Final stress intensity factor, Kip(a,P) = 0 ksi'/in 39.849 ksi/in 63.597 ksi'iin Page E-1

Controlled Document A Document No. 32-9136508-001 AREVA AREVA NP Inc.,

an AREVA and Siemens company DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair Table E-1: Stress Intensity Factors for Internal Pressure Loading Temperature = 600 F Pressure = 2500. psig Flaw size = 2.035, in.

Position SIF (ksi~in)

Inside Surface 1 56.697 2 51.258 3 49.563 4 48.028 5, 46.116 6 43.286 7 39.883 8 41.978 9 50.267 Bored Surface 10 56.952 70 60 50___ __

40 30 20 Press 10__ _ _ _

1 2 3 4 5 6 7 8 9 10 Position Page E-2

Enclosure B L-1 0-131 Affidavit for DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair (3 pages follow)

AFFIDAVIT COMMONWEALTH OF VIRGINIA )

) ss.

CITY OF LYNCHBURG )

1. My name is Gayle F. Elliott. I am Manager, Product Licensing, for AREVA NP Inc. and as such I am authorized to execute this Affidavit.

2. I am familiar with the criteria applied by AREVA NP to determine whether certain AREVA NP information is proprietary. I am familiar with the policies established by AREVA NP to ensure the proper application of these criteria.

3. I am familiar with the AREVA NP information contained in Calculation Summary Sheet (CSS) 32-9134664-002 entitled "DB-1 CRDM Nozzle J-Groove Weld Flaw Evaluation for IDTB Repair," dated April 2010 and referred to herein as "Document."

Information contained in this Document has been classified by AREVA NP as proprietary in accordance with the policies established by AREVA NP for the control and protection of proprietary and confidential information.

4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by AREVA NP and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5. This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is

requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."

6. The following criteria are customarily applied by AREVA NP to determine whether information should be classified as proprietary:

(a) The information reveals details of AREVA NP's research and development plans and programs or their results.

(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for AREVA NP.

(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for AREVA NP in product optimization or marketability.

(e) The information is vital to a competitive advantage held by AREVA NP, would be helpful to competitors to AREVA NP, and would likely cause substantial harm to the competitive position of AREVA NP.

The information in the Document is considered proprietary for the reasons set forth in paragraphs 6(b) and 6(c) above.

7. In accordance with AREVA NP's policies governing the protection and control of information, proprietary information contained in this Document have been made available, on a limited basis, to others outside AREVA NP only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8. AREVA NP policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.

SUBSCRIBED before me this 20 dayof !Al 2010.

Sherry L. McFaden NOTARY PUBLIC, COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES: 10/31/10 Reg. # 7079129 SHERRY L.MCFAOEN Notary Public IJ Commonwealth of Vlfginla, My Cm 7079129 1 201In Of"MISSIOn EXCIres Oct 31