davis-besse, unit 1, enclosure a to l-12-444, calculation ... · davis-besse nuclear power station,...

Enclosure A

Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse)

Letter L-12-444

Calculation 32-9195423-000,"DB-1 EMA of RPV Inlet & Outlet Nozzle-to-Shell Welds for 60 Years -

Non-Proprietary"

26 pages follow

For Information Only0402-01-FOI (Rev. 017, 11/19/12)

A CALCULATION SUMMARY SHEET (CSS)AREVA

Document No. 32 9195423 - 000 Safety Related: 0 Yes [-]No

Title DB-1 EMA of RPV Inlet & Outlet Nozzle-to-Shell Welds for 60 Years - Non - Proprietary

PURPOSE AND SUMMARY OF RESULTS:

AREVA NP Inc. proprietary information in the document are indicated by pairs of braces " [ I".Purpose: The reactor vessel inlet and outlet nozzle-to-shell welds are evaluated for low upper-shelf energy levelsby linear elastic fracture mechanics analytical techniques to satisfy the requirements of Appendix K to Section XIof the ASME Boiler and Pressure Vessel Code [4].

Summary: The analysis is based on an upper bound surface fluence of 0.23 x 1018 n/cm 2 [15] at 60 calendar yearsor 52 Effective Full Power Years (EFPY), calculated at the lowest elevation of the outlet nozzle-to-shell weld.Stresses are derived at the weld location considering the influence of the nozzle-to-shell geometric discontinuityand attached piping reaction for Level A, B, C and D service loadings. The reactor vessel nozzle-to-shell weldssatisfy all acceptance criteria of ASME Code, Section XI, Article K-2000. For Level A and B service loading, theapplied J-integral at 1.15 times the accumulation pressure plus thermal loadings is less than the J-integral of thematerial at a ductile flaw extension of 0.10 in. by a margin of 1.27. The applied J-integral for Level C and DService loadings is less than the required measure of J-integral resistance by a margin of 1.2. Furthermore, thecriterion for ductile and stable flaw extensions is satisfied for Level A, B, C, and D service loadings.

THE DOCUMENT CONTAINSASSUMPTIONS THAT SHALL BE

THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: VERIFIED PRIOR TO USE

CODE/VERSIONIREV CODE/VERSIONIREVS'1YESPCRIT/6/3 Z]NO

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AREV0402-01-FOl (Rev. 017, 11/19/12)

Document No. 32-9195423-000

NON-PROPRIETARY

DB-1 EMA of RPV Inlet & Outlet Nozzle-to-Shell Welds for 60 Years

Review Method: N Design Review (Detailed Check)

D Alternate Calculation

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S. J. Noronha P ALL

Engineer IV "IiIt2-

Ashok D. Nana R j4 fALLSupervisoryEngineer__________

T. M. Wiger ,h€ul A ALLTechnical Manager Wj4fi#7J,74•,.-

Note: P/R/A designates Preparer (P), Reviewer (R), Approver (A);LP/LR designates Lead Preparer (LP), Lead Reviewer (LR)

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AAREVA

For Information Only

0402-01-FOl (Rev. 017, 11/19/12)Document No. 32-9195423-000

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Record of Revision

Revision Pages/Sections/ Paragraphs

No. Changed Brief Description / Change Authorization

000 ALL Original Release

i- i

I. *1

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AAR EVA Document No. 32-9195423-000

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Table of Contents

Page

SIGNATURE BLOCK ................................................................................................................................ 2

RECO RD O F REVISION ..................................................... ............................................................ 3

L IS T O F T A B L E S ..................................................................................................................................... 6

LIST O F FIGURES ...................................................................................................... 7

1.0 INTRODUCTIO N ........................................................................................................................... 8

2.0 ANALYTICAL M ETHO DOLOGY ............................................................................................. 8

2.1 Acceptance Criteria ......................................................................................................................... 8

2.1.1 Level A and B Service Loadings (K-2200) ..................................................................... 9

2.1.2 Level C Service Loadings (K-2300) .............................................................................. 9

2.1.3 Level D Service Loadings (K-2400) .............................................................................. 9

2.2 Temperature Range for Upper-Shelf Fracture Toughness Evaluations ..................................... 9

2.3 Effect of Cladding Material ........................................................................................................ 10

3.0 ASSUM PTIO NS .......................................................................................................................... 10

4.0 DESIGN INPUT .......................................................................................................................... 10

4 .1 G e o m e tric D a ta .............................................................................................................................. 10

4 .2 M a te ria ls D a ta ................................................................................................................................ 10

4.3 J-integral Resistance Model for Mn-Mo-Ni/Linde 80 W elds ...................................................... 11

4 .4 A p p lie d Lo a d in g s ............................................................................................................................ 12

4.4.1 Pressure and Thermal Discontinuity Stresses ........................................................... 12

4.4.2 Shell Stresses at the W eld Location ............................................................................ 12

4.4.3 Stresses from Attached Piping Loads ......................................................................... 13

4.4.4 Total Stresses ............................................................................................................. 13

4 .5 F lu e n ce L ev e ls ............................................................................................................................... 14

5.0 CALCULATIO NS .......................................................................................................... ........ 14

5.1 Evaluation for Level A & B Service Loadings ............................................................................ 14

5.2 Evaluation for Level C & D Service Loadings ...................................... 18

6.0 RESULTS .................................................................................................................................. 25

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Table of Contents(continued)

Page

7 .0 R E F E R E N C E S .............................................................................................................. ............. 2 5

APPENDIX A: COMPUTER OUTPUT FILES AND VERIFICATION OF PCRIT ......... ............. 26

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.AAR EVA Document No. 32-9195423-000

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List of Tables

Page

Table 4-1: Mechanical Properties of Weld Materials ........................................................................ 11

Table 4-2: Applicable Pressure and Thermal Discontinuity Stresses for Flaws ................................ 12

Table 4-3: Shell stresses at the w eld location .................................................................................... 13

Table 4-4: Stresses due to the Attached Pipe Loads ........................................................................ 13

Table 4-5: Level A and B Service Loadings ...................................................................................... 13

Table 4-6: Level C and D Service Loadings (without thermal stresses) ...................... 14

Table 5-1: Flaw Evaluation for Level A & B Service Loadings ......................................................... 15

Table 5-2: Flaw Evaluation for Level A & B Service Loadings .......................................................... 16

Table 5-3: Flaw Evaluation for Level C & D Service Loadings ......................................................... 21

Table 5-4: Flaw Evaluation for Level C & D Service Loadings ......................................................... 22

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List of Figures

Page

Figure 5-1: J-R Curves for level A & B Service Loadings ................................................................ 17

Figure 5-2: Level C and D Transients - Reactor Coolant Temperature versus Time ............. 18

Figure 5-3: Level C and D Transients - Reactor Coolant Pressure versus Time ............................. 19

Figure 5-4: Level C and D Transients - Heat Transfer Coefficient vs Time .................................... 19

Figure 5-5: Kle, Kj, (mean and lower bound), and Applied K, for Level C and D .............................. 20

Figure 5-6: J-R Curves for Level C & D Service Loadings ................................................................ 24

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AARE VA Document No. 32-9195423-000

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1.0 INTRODUCTION

Reactor vessel beltline materials exhibiting Charpy upper-shelf impact energy levels below 50 ft-lbs are requiredby Appendix G[l1, "Fracture Toughness Requirement," to 10 CFR Part 50, "Domestic Licensing of Production andUtilization Facilities," to be analyzed to show that margins of safety against fracture are equivalent to thoserequired by Appendix G of the ASME Code[4]. Welds in the beltline region of Davis-Besse Unit 1 (DB-1) reactorvessel (RV) have recently been analyzed for 60 years or 52 effective full power years (EFPY) of operation todemonstrate that these low upper-shelf energy materials would continue to satisfy federal requirements forlicense renewal [2,3]. Although subject to lower fluence levels than the reactor vessel beltline region, weldmaterials that are used to attach the primary coolant inlet and outlet nozzles to the reactor vessel are alsosusceptible to fracture toughness degradation from neutron embrittlement. These structural welds are subjectedto nozzle-to-shell discontinuity stresses and attached piping loads that are not applicable to the beltline regionanalyzed in Reference [2]. The purpose of the present analysis is to evaluate the welds that attach the inlet andoutlet nozzle to the reactor vessels (Material ID, WF-233[3]), even though the projected upper-shelf energy levelsat 52 EFPY is slightly above 50 ft-lbs [3] for the Davis-Besse Unit 1. This equivalent margin fracture mechanicsevaluation is performed according to the guidelines and acceptance criteria of Appendix K to Section Xl of theASME Boiler and Pressure Vessel Code [4]..

The present analysis will consider both the inlet and outlet nozzles. For the purposes of the present fracturemechanics evaluation, the primary coolant [ ] inlet and [ ] outlet nozzle are similar in that the full

penetration attachment welds are located in the [ ] thick nozzle belt forging (NBF) section of the reactorvessel shell [9, 10]. Envelop stresses from outlet and inlet nozzles for attached pipe loads [5] will be considered.Due to the close proximity of the larger diameter outlet nozzle to the reactor core, the outlet nozzle-to-shell weld issubjected to higher levels of fluence than the inlet nozzle. Stresses from available sources will be utilized tocharacterize Level A and B service loadings. Previously derived pressure stresses will also be used to analyzethe nozzle-to-shell interface area for Level C and D Service loadings. Thermal stresses for Level C and D Serviceloadings will be developed using PCRIT [16] for the most limiting transient for the nozzle belt forging section.

2.0 ANALYTICAL METHODOLOGY

Appendix K to Section XI of the ASME Code [4] provides acceptance criteria (described in section 2.1) andevaluation procedures for determining acceptability of low upper-shelf materials in the cylindrical shallow portionof the reactor vessel. Although the nozzle-to-shell weld will be subjected to the acceptance criteria of Appendix K,the linear elastic fracture mechanics procedures of Appendix K will be augmented to account for the membraneand bending discontinuity stresses at the intersection of the nozzle and nozzle belt forgings. Although it may beargued that stress intensity factors could be calculated using solutions for semi-elliptical flaws in cylindricalvessels, it is conservative to utilize a flat plate solution for this purpose. Accordingly, semi-elliptical surface flawsin the nozzle-to-shell weld will be analyzed using a flat plate solution by Newman and Raju [6].

2.1 Acceptance Criteria

Acceptance criteria for the assessment of reactor vessels with low upper shelf Charpy impact levels areprescribed in Article K-2000 of Appendix K to Section XI of the ASME Code [4]. These criteria are summarizedbelow as they pertain to the evaluation of reactor vessel weld metals.

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2.1.1 Level A and B Service Loadings (K-2200)

(a) When evaluating adequacy of the upper shelf toughness for the weld material for Level A and BService Loadings, an interior semi-elliptical surface flaw with a depth 1/4 of the wall thickness anda length six times the depth shall be postulated, with the flaw's major axis oriented along the weldof concern and the flaw plane oriented in the radial direction. Two criteria shall be satisfied:

(1) The applied J-integral evaluated at a pressure 1.15 times the accumulation pressure (Pa)as defined in the plant specific Overpressure Protection Report, with a factor of safety of1.0 on thermal loading for the plant specific heatup .and cooldown conditions, shall beless than the J-integral of the material at a ductile flaw extension of 0.10 in.

(2) Flaw extensions at pressures up to 1.25 times the accumulation pressure (P,) shall beductile and stable, Using a factor of safety of 1.0 on thermal loading for the plant specificheatup and cooldown conditions.

(b) The J-integral resistance versus flaw extension curve shall be a conservative representation forthe vessel material under evaluation.

2.1.2 Level C Service Loadings (K-2300)

(a) When evaluating the adequacy of the upper shelf toughness for the weld material for Level CService Loadings, interior semi-elliptical surface flaws with depths up to 1/10 of the base metal wallthickness, plus the cladding thickness, with total depths not exceeding 1.0 in., and a surfacelength six times the depth, shall be postulated, with the flaw's major axis oriented along the weldof concern, and the flaw plane oriented in the radial direction. Flaws of various depths, rangingup to the maximum postulated depth, shall be analyzed to determine the most limiting flaw depth.Two criteria shall be satisfied:

(1) The applied J-integral shall be less than the J-integral of the material at a ductile flaw

extension of 0.10 in., using a factor of safety of 1.0 on loading.

(2) Flaw extensions shall be ductile and stable, using a factor of safety of 1.0 on loading.

(b) The J-integral resistance versus flaw extension curve shall be a conservative representation forthe vessel material under evaluation.

2.1.3 Level D Service Loadings (K-2400)(a) When evaluating adequacy of the upper shelf toughness for Level D Service Loadings, flaws as

specified for Level C Service Loadings shall be postulated, and toughness properties for thecorresponding orientation shall be used. Flaws of various depths, ranging up to the maximumpostulated depth, shall be analyzed to determine the most limiting flaw depth. Flaw extensionsshall be ductile and stable, Using a factor of safety of 1.0 on loading.

(b) The J-integral resistance versus flaw extension curve shall be a best estimate representation forthe vessel material under evaluation.

(c) The extent of stable flaw extension shall be less than or equal to 75% of the vessel wallthickness, and the remaining ligament shall not be subject to tensile instability.

2.2 Temperature Range for Upper-S helf Fracture Toughness Evaluations

Upper-shelf fracture toughness is determined through use of Charpy V-notch impact energy versus temperatureplots by noting the temperature above which the Charpy energy remains on a plateau, maintaining a relatively

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For nformation Only

AAREVA. Document No. 32-9195423-000

NON-PROPRIETARY


high constant energy level. Similarly, fracture toughness can be addressed in three different regions on thetemperature scale, i.e. a lower-shelf toughness region, a transition region, and an upper-shelf toughness region.Fracture toughness of reactor vessel steel and associated weld metals are conservatively predicted by the ASMEinitiation toughness curve, K1c, in the lower-shelf and transition regions. In the upper-shelf region, the upper-shelftoughness curve, Kjo is derived from the upper-shelf J-integral resistance model 'described in Section 4.3. Theupper-shelf toughness then becomes a function of fluence, copper content, temperature, and fracture specimensize. When upper-shelf toughness is plotted versus temperature, a plateau-like curve develops that decreasesslightly with increasing temperature. Since the present analysis addresses the low upper-shelf fracture toughnessissue, only the upper-shelf temperature range, which begins at the intersection of K1c and the upper-shelftoughness curves, Kj, is considered.

2.3 Effect of Cladding Material

The PCRIT [16] code utilized in the flaw evaluations for Level C and D Service Loadings does not considerstresses due to thermal expansion in the cladding when calculating stress intensity factors. To account for thiscladding effect, an additional stress intensity factor, K/clad, is calculated separately and added to the total stressintensity factor computed by PCRIT.

The contribution of cladding stresses to stress intensity factor was examined previously [7]. In the low upper-shelffracture toughness analysis performed for B&W Owners Group Reactor Vessel Working Group plants [13], themaximum value of K1clad, at any time during the analyzed transients and for any flaw depth, was determined to be[ ] ksi•iin [7]. This bounding value .is therefore used as the stress intensity factor for KicIld in this Davis-Besse low upper-shelf fracture toughness analysis.

3.0 ASSUMPTIONS

This document contains no assumptions that require verification before use for safety related applications. Apertinent minor assumption is that, conservatively semi-elliptical flaws in flat plates were used instead of semi-elliptical flaws in cylindrical vessels.

4.0 DESIGN INPUT

The normal operating temperature at the outlet nozzle is 608°F [8] and at the inlet nozzle is 550°F [8].

4.1 Geometric Data

From a review of sub-assembly drawings for both the outlet [9] and inlet nozzles [10], the thickness of the reactor

vessel nozzle-to-shell weld is taken to be [ ] . The radius of the reactor vessel nozzle-to-belt forging at

the cladding is [ ] and at the base metal is [ ] [11]. Thus the cladding thickness is

I ] and the outer radius of the reactor vessel at this forging is [ ]

4.2 Materials Data

The reactor vessel inlet and outlet nozzle-to-shell welds are formed from Mn-Mo-Ni/Linde 80 weld materials. Themechanical properties of the Linde 80 metals are given in Table 4-1, along with the ASME code values [12] for thebase metal. The weld materials properties are based on tests conducted on samples from surveillance capsuleand are reported in reference [2].

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Document No. 32-9195423-000NON-PROPRIETARY


Table 4-1: Mechanical Properties of Weld Materials

Temp(°F) E(ksi) Yield strength, ay(ksi) a (/OF)

Material: Base Metal Base Metal Weld metal Base Metal

Source: Code j12] Code[12] Test Data [2] Code[12]

100.0 27800 50.00 87.30 6.50E-06

200.0 27100 47.50 84.81 6.67E-06

300.0 26700 46.10 82.89 6.87E-06

400.0 26100 45.10 80.98 7.07E-06

500.0 25700 44.50 79.06 7.25E-06

550.0 25450 44.11 78.10 7.34E-06

600.0 25200 43.80 77.14 7.42E-06

4.3 J-integral Resistance Model for Mn-Mo-Ni/Linde 80 Welds

A model for the J-integral resistance versus crack extension curve (J-R curve) required to analyze low upper-shelfenergy materials have been derived specifically for Mn-Mo-Ni/Linde 80 weld materials. A previous analysis of thereactor vessels of B&W Owners 'Reactor Vessel Working Group' [13] described the development of thistoughness model from a large data base of fracture specimens. Using a modified power law to represent the J-Rcurve, the mean value of the J-integral is given by:

where

and

also,

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AAREVA Document No. 32-9195423-000

NON-PROPRIETARY


As dictated by paragraph K-2000(b) of Reference [4], the J-integral resistance versus flaw extension curve is aconservative representation for the vessel material under evaluation. The conservatism is introduced bymultiplying the mean value of the J-integral calculated from the model by a factor of [ ] , which is twicethe standard error (-2Se) of the test data used to create the model [13].

4.4 Applied Loadings

In the area of the nozzle-to-shell weld, applied loadings consist of pressure, thermal and attached pipingreactions. Stresses from pressure and piping loads are obtained from previously documented analyses [5, 14], asare thermal stresses for level A and B service loadings [5, 14]. Thermal stresses are derived as part of theanalysis performed using PCRIT herein for Level C and D service loadings.

4.4.1 Pressure and Thermal Discontinuity Stresses

Stresses due to pressure and thermal loads at the nozzle-to-shell discontinuity are obtained from a previousanalysis of the TMI-1 outlet nozzle [14]. These stresses are then scaled by the applicable pressure loading toderive the stresses required for the subsequent low upper-shelf energy analysis. In the calculations that follow,the design pressure, Pd is taken to be [ ] psi. Level A and B service loadings are based on the cooldowntransient since it produces tensile stresses at the inside surface of the nozzle-to-shell intersection. Stresses arederived for hot leg LOCA pressure conditions since it was determined that this event was the limiting transient forLevel C and D service loadings in the low upper shelf analysis performed for the belt line region [2].

Table 4-2: Applicable Pressure and Thermal Discontinuity Stresses for Flaws

Internal Surface Stresses Membrane BendingCondition Pressure Inside Outside Stress Stress

(ksi) (ksi) (ksi) (ksi) (ksi)RV Outlet Nozzle Stress Analysis[14]:

Initial pressure, Po [ ] [ ] [ i [ I ]

Cooldown (pressure + thermal) _[_ _] ]._I _L _ _Intermediate Loadings:

Accumulation pressure, Pa=l.1 *Pd [ ] ] [ ] [ ] [ ICooldown (pressure only)

Cooldown (thermal only) I ,_ L I I I IAppendix K, Level A & B Service Loadings:

1.15*Pa + Thermal IC ]I[ ] T ( [C ]1.25*Pa + Thermal II_ 1.L._ _ __ . I

Appendix K, Level C & D Service PressureLoadings:

Hot Leg LOCA at max. pressure [ JI [ ] ] IC [Hot Leg LOCA at min. pressure 1 1i.LJ][ L1 [ ] L

4.4.2 Shell Stresses at the Weld Location

The normal/upset condition load combination is dead weight (DW) + thermal (TH) + Operating Basis Earthquake(OBE) loads [5]. The load combination for emergency/faulted condition includes DW+ TH + Square root of sum ofsquares (SRSS) of Safe Shutdown Earthquake (SSE) and Loss of Coolant (LOCA) transients. Circumferential

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and longitudinal bounding stresses for both outlet nozzle and inlet nozzles are conservatively used (location 3 inReference [5].) The stresses are listed below:

Table 4-3: Shell stresses at th e weld location

Circumferential LongitudinalSurface Stresses

Condition [51 Stresses Surface Stresses [51 StressesInside Outside Membrane Bending Inside Outside Membrane Bending(ksi (ksi) (ksi) (ksi) (ksi) (ksi) (ksi) (ksi)

Normal/UpsetEmergency/Faulted

[ l [ l[ I_ [ ]I I I I I II ) I [

III I.] 1 I I

4.4.3 Stresses from Attached Piping Loads

Stresses at the nozzle-to-shell intersection due to nozzle loads from the attached hot leg piping have recentlybeen determined for the DB-1 plant [5]. Circumferential and longitudinal bounding stresses for both outlet nozzleand inlet nozzles are conservatively used (location 3 in reference [5]).

Table 4-4: Stresses due to the Attached Pipe Loads

Circumferential LongitudinalSurface Stresses

Condition .[51 Stresses Surface Stresses[5] StressesInside Outside Membrane Bending Inside Outside Membrane Bending

(ksi) (ksi) (ksi) (ksi) (ksi) (ksi) (ksi) (ksi)

Normal/Upset I ] I ]

J L

[

-I] I I] I ] I ] [ ] [ ]

[ ]I [ IEmergency/Faulted I[ _II I__ _]__ I II I I

4.4.4 Total Stresses

The combined stresses listed below are formulated to provide necessary input to the low upper-shelf analysis thatfollows.

Table 4-5: Level A and B Service Loadings

Circumferential LongitudinalCondition Stresses Stresses

Membrane Bending Membrane Bending(ksi) (ksi) . (ksi) (ksi)

1.15*Pa + Thermal + Piping Loads1.25*Pa + Thermal + Piping Loads

[ ]II] [

I I I I

Pae1

C 1 ] I

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Table 4-6: Level C and D Service Loadings (without thermal stresses)

Circumferential LongitudinalCondition Stresses Stresses

Membrane Bending Membrane Bending(ksi) (ksi) I (ksi) (ksi)

HL-LOCA at max. pressure + Piping Loads [ ] [HL-LOCA at min. pressure + Piping Loads [ ] J] j[ ]

4.5 Fluence Levels

At 52 EFPY, an upper bound surface fluence is estimated [15] to be 0.23 x 1018 n/cm2 at the lowest elevation ofthe outlet nozzle-to-shell weld. This fluence is nearly two orders of magnitude lower than the maximum value of16.9 x 1018 nicm2 used in the low upper-shelf analysis of the belt line region [2].

5.0 CALCULATIONS

Level A and B service loadings were described in Section 4.4 as were pressure and attached piping stresses forLevel C and D service loadings. The PCRIT [161 computer code was utilized to obtain stress intensity factors dueto hot leg LOCA thermal conditions since it was determined that this event was the limiting transient for Level Cand D service loadings. in the low upper-shelf analysis performed for the belt line region [2]. PCRIT alsocalculates a stress intensity factor from residual stresses in the weld. A stress intensity factor associated with thecladding/base metal thermal discontinuity gradient is also included by adding a value of [ ] ksilin to thesum of stress intensity factors due to pressure, attached piping, PCRIT thermal, and PCRIT residual stresses.

The hot leg LOCA transient is described in documentation for the low upper-shelf analysis of the beltline region[2]. The PCRIT run for the hot leg LOCA event is attached in the form of COLDSTOR files listed in Appendix A.The output file also includes a listing of the input records. PCRIT is also verified for use in the present analysisand is reported in Appendix A.

5.1 Evaluation for Level A & B Service Loadings

Initial flaw depths equal to 1/4 of the vessel wall thickness are analyzed for Level A and B Service Loadingsfollowing the procedure outlined in Section 2.0 and evaluated for acceptance based on values for the J-integralresistance of the material from Section 4.3. The results of the evaluation are presented in Table 5-1 and Table5-2, where it is seen that the minimum ratio of material J-integral resistance (J0.1) to applied J-integral (J1) is 1.27and 1.7 for flaws oriented in the axial and circumferential direction with respect to the RV, which are higher thanthe minimum acceptable value of 1.0.

The flaw evaluation for the weld (material ID WF-233) is repeated by calculating applied J-integrals for variousamounts of flaw extension with safety factors (on pressure) of 1.15 and 1.25 in Table 5-2. The results, along withmean and lower bound J-R curves developed in Table 5-2, are plotted in Figure 5-1. An evaluation line at a flawextension 0.10 in. is also included to confirm the results of Table 5-1 by showing that the applied J-integral for asafety factor of 1.15 is less than the lower bound J-integral resistance of the material. The requirement for ductileand stable crack growth is also demonstrated by Figure 5-1 since the slope of the applied J-integral curve for asafety factor of 1.25 is considerably less than the slope of the lower bound J-R curve at the point where the twocurves intersect.

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Table 5-1: Flaw Evaluation for Level A & B Service Loadings

Flaw characterization

aot =

ao =da =

a=a/t=

I/a =I=C=

a/c=

in.in.in.

(initial flaw depth)(flaw extension)(flaw depth at extension)

in. (flaw length)in. (flaw half length)

Geometry factors for use in stress intensity factor equation

4 (at deepest point) = iT/2M, = 1.13 - 0.09 (a/c)

M2 = -0.54 + 0.89/[0.2+(a/c)]

M3 = 0.5 - 1.0/[0.65+(a/c)] + 14 [1.0-(a/c)]24

= [(a/c)2(cos((0))2 + (sin(0))2]0.25

fw= [sec(7c/(2W)(a/t)0 5)]0 5 (assume = 1.0)g = 1 + [0.1 + 0.35 (a/t)2] [1-sin(4)] 2

p = 0.2 + (a/c) + 0.6 (a/t)G1 = -1.22 - 0.12 (a/c)

G2 = 0.55 - 1.05 (a/c)07 5 + 0.47 (a/c)'5

H1 = 1.0 - 0.34 (a/t) - 0.11 (a/c) (a/t)

H2 = 1.0 + G1 (a/t) + G2 (a/t)2

Q = 1.0 + 1.464 (a/c)1 65

F = [M1 + M2 (a/t)2 + M3 (a/t)4] fo fw g

H = H1 + (H2 - H1) (sin(4))p

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Table 5-2: Flaw Evaluation for Level A & B Service Loadings

Stresses for Levels A and B Service Loadings

Safety Factor = 1.15 Safety Factor = 1.25Stress Direction Stress DirectionCirc. Long. Circ. Long.

Membrane stress, Sm s]Bending stress, Sb EF i Ik js:

Stress intensity factor

Kj(a/t,a/c,cIW,0) = [Sm + H Sb F [ 7 a/Q

Plastic zone correction

ry= 1/(6 7r) (KI(a)/SY)2

ae = a + ry

Corrected stress intensity factor

KI(ae) =[Sm + H Sb ] F [i ae/Q 0.5

IL ksi~~in

in.in.

ýýksN]n

Equivalent J-integral

Applied J-integral = J1 = 1000 [KI(ae)] 2 / [E/(1-v 2)]:

[LLEvaluation of the applied J-integral at a ductile flaw extension of 0.10 in.

J-integral resistance at a ductile flaw extension of 0.10" = J 0.1 = . ilb/in

Safetry Factor = 1.15Stress DirectionCirc. Long.

Ratio J 0.1 /J1 1.27 I1.70I

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Figure 5-1: J-R Curves for level A & B Service Loadings

1400

1200

1000

. 800.0

"¢ 600

400

200

0 1 10.00 0.05 0.10 .0.15 0.20 0.25 0.30 0.35 0.40

Flaw Extension, da (in.)

0.45 0.50

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5.2 Evaluation for Level C & D Service LoadingsA flaw depth of 1.0 inch is used to evaluate the Level C and D Service Loadings. The stress intensity factor K,calculated by the PCRIT code is the sum of thermal, residual stress, deadweight, and pressure terms. PCRIT isrun for Hot Leg LOCA transient, the input used in the current analysis are described below.

Fluence at 52 EFPY = 0.23e18 n/cm2 [15]Percentage of Copper content = .21%[17]

Percentage of Ni Content = .65% [17]RTNDT = -5.0 °F[18]Margin = 68.5 °F[18]

Geometry data used is the same as that mentioned in Section 4.1. The materials properties used are the sameas that listed in Section 4.2. Weld type used is Double-J circ weld, the closest to existing weld as per thedrawings [9, 10]. Initial vessel wall temperature is taken as the normal operating inlet temperature, [ ] OF[9]. The transient temperature, pressure and heat transfer coefficients used are plotted in Figure 5-2, Figure 5-3and Figure 5-4 respectively. They are the same as that used for the EMA analysis of beltline welds [2] and areobtained from the COLDSTOR of Reference [2].

Figure 5-2: Level C and D Transients - Reactor Coolant Temperature versus Time

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Figure 5-3: Level C and D Transients - Reactor Coolant Pressure versus Time

Figure 5-4: Level C and D Transients - Heat Transfer Coefficient vs Time

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Figure 5-5: Kic, Kjc (mean and lower bound), and Applied K1 for Level C and D

Fracture Toughness Margins for HL LOCA atda= 0.10 in.

500 I I

450 - - - Kjc Mean

-Kjc Lower Bi

400 . . . . Klappl (uppe

350 Kic

350 ... - -Evaluation p

U 300 ____ ___ _______

" 250• minut~esl

100 - - ____ .,,

50 I

0150 200 250 300 350 400 450

T(0 F)

500 550

Figure 5-5 shows the variation of applied stress intensity factor, Kh, transition toughness, Kjc, and upper shelf-toughness, K with temperature In the upper shelf-toughness range, the K, curve is closest to the lower boundK& curve at 10.01 minutes into the transient. This time is selected as the critical time in the transient at which toperform the flaw evaluation for Level C and D service loadings.

Applied J-integrals are calculated for the weld for flaw depth of 1.0 inch in Table 5-3 using stress intensity factors

from PCRIT for the Hot Leg Large Break LOCA (at 10.01 min.) and adding I I ksiqin [7] to account forcladding effects. Stress intensity factors are converted to J-integrals by the plain strain relationship,

J-apid (a) = 1000 (l -_ 2)E

Table 5-3 lists flaw extensions evaluation parameters. As the Davis-Besse vessel is [ ] in. thick, 1/10 of

the wall thickness is [ ] in., so an initial flaw depth of 1.0 in used as per Appendix K- guidelines. Flawextension from this depth is calculated by subtracting 1.0 in. from the built-in PCRIT flaw depths. The results,along with mean and lower bound J-R curves developed in Table 5-3 and Table 5-4, and are plotted in Figure 5-6.An evaluation line is used at a flaw extension of 0.10 in. to show that the applied J-integral is less than the lowerbound J-integral of the material, as required by Appendix K [2]. The requirements for ductile and stable crackgrowth are also demonstrated by Figure 5-6 since the slope of the applied J-integral curve is considerably lessthan the slopes of both the lower bound and mean J-R curves at the points of intersection.

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Referring to Figure 5-6, the Level D Service Loading requirement that the extent of stable flaw extension be nogreater than 75% of the vessel wall thickness is satisfied since the applied J-integral curve intersects the mean J-R curve at a flaw extension that is only a small fraction of the wall thickness (less than 1%).

The PCRIT computer output files for the Level C and D Service Loadings analysis of the transients discussedhere are stored on COLDSTOR as listed in Appendix A. The output file also includes a listing of the inputrecords. PCRIT is verified for use in the present analysis and output of the test files are listed in Appendix A.

Table 5-3: Flaw Evaluation for Level C & D Service Loadings

Base metal flaw characterization

Initial total flaw depth min t/10 + cladding thickness, 1.0 3•- n.

Initial flaw depth, a, = n. (total flaw depth - cladding thickness)ao/t =

da = n. (flaw extension)a = n. (flaw depth at extension)

alt =

I/a =I= n. (flaw length)

c = n. (flaw half length)a/c =

Geometry factors for use in stress intensity factor equation

4(at deepest point) = 7r/2M, = 1.13 - 0.09 (a/c)M2 = -0.54 + 0.89/[0.2+(a/c)]

M3 = 0.5 - 1.0/[0.65+(a/c)] + 14 [1.0-(a/c)]24

f= [(a/c) (cos(4))2 + (sin(0))2]0.25

fw= [sec(iTc/(2W)(a/t)0 5 )]0.5 (assume = 1.0)

g = 1 + [0.1 + 0.35 (a/t)2] [1-sin(4)] 2

p= 0.2 + (a/c) + 0.6 (a/t)G1 = -1.22 - 0.12 (a/c)

G2 = 0.55 - 1.05 (a/c)°75 + 0.47 (a/c)1 5

H1 = 1.0 - 0.34 (a/t) - 0.11 (a/c) (a/t)

H2 = 1.0 + G1 (a/t) + G2 (a/t)2

Q = 1.0 + 1.464 (a/c)16 5

F = [M1 + M2 (a/t)2 + M3 (a/t)4] fý fw g

H= H1 + (H2 - H1) (sin(4))p

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Table 5-4: Flaw Evaluation for Level C & D Service Loadings

At time = 0 (Pressure loads dominate):

Stress DirectionCirc. Long.

Membrane stress, Sm [ ksi Maximum pressureBending stress, Sb L. ksi plus piping loads


Kj(a/t,a/c,c/W,4) = [Sm + H Sb ]

Pressure + piping loadsPCRIT thermal loads

Residual loadsCladding thermal gradient

Total


ry 1/(6 it) (KI(a)/SY)2

ae a +ry

Corrected stress intensity fac

KI(ae) = [ Sm + HSb ] F [iT ae/Q



Total


F [7r a/Q ]05

ksi'inksi•inksilinksi'/inksi'4in

tor

]05

ksi'in

ksi'Iin

-ksi~Iin

Applied J-integral = J, = 1000 [Kj(ae)] 2 / [E/(I-v2 )]:

LL I_.• lb/in

Evaluation of the applied J-integral at a ductile flaw extension of 0.10 in.

J-integral resistance at a ductile flaw extension of 0.10" = J 0.1 =[z----lb/in

Stress Direction

Circ" LonRatio J 0.1/J 1

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Table 5-4: Flaw Evaluation for Level C & D Service Loadings (Cont'd)

At time = 10.01 min. (Thermal loads dominate):

Stress DirectionCirc. I Long.

Membrane stress, Sm

Bending stress, Sb

F- ksiksi

Minimum pressureplus piping loads


Kj(a/t,a/c,cVW,4) = [Sm + H Sb ] F [7r aIQ ]0.5



Total


ksi'linksi'inksr~inksi'inksi'in

ry 1/(6 Ti) (K,(a)/Sy)2

ae= a +ry

Corrected stress intensity factor

KI(ae) =[Sm + H Sb ] F [1 ae/Q ] 0.5



Total

ksi'linksi'linksi'inksi'inksilin


Applied J-integral = J, = 1000 [KI(ae)]2 / [E/(1-v 2)]:

L7.- Illb/in

Evaluation of the applied J-integral at a ductile flaw extension of 0.10 in.

J-integral resistance at a ductile flaw extension of 0.10" = J0 1 =C••]lb/in

StrssDirection

Circ I ongRatio J0.1/J1

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Figure 5-6: J-R Curves for Level C & D Service Loadings

2500

2000

C

1500

1000

500

0-

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Flaw Extension, da (in.)

0.35 0.40 0.45 0.50

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6.0 RESULTS

The reactor vessel inlet and outlet nozzle-to-shell welds were evaluated for low upper-shelf energy levels by linearelastic fracture mechanics analytical techniques to satisfy the requirements of Appendix K of ASME Code [4].The analysis is based on an upper bound surface fluence of 0.23 x 1018 n/cm2 at 52 EFPY, calculated at thelowest elevation of the outlet nozzle-to-shell weld. This fluence is nearly two orders of magnitude lower than themaximum value of 16.9 x 1018 n/cm 2 utilized for low-upper shelf analysis of the beltline region [2]. Stresses werederived at the weld location considering the influence of the nozzle-to-shell geometric discontinuity and attachedpiping reactions for Level A, B, C, and D service loadings.

The reactor vessel nozzle-to-shell welds satisfy all acceptance criteria of ASME Code, Section XI, Article K-2000[4]. For Level A and B service loadings, the applied J-integral of the material at 1.15 times the accumulationpressure, plus thermal loadings is less than the J-integral of the material at a ductile flaw extension of 0.10", by amargin of 1.27. The applied J-integral for Level C Service loadings is less than the required measure of J-integralresistance by a margin of 1.20. Furthermore, the criterion for ductile and stable flaw extensions is satisfied for allLevel A, B, C and D service loadings.

7.0 REFERENCES

1. Code of Federal Regulations, Title 10, Part 50 - Domestic Licensing of Production and Utilization Facilities,Appendix G - Fracture Toughness Requirements, March 10, 2010

2. AREVA NP Document No. 32-5017465-003, "Low Upper-Shelf Toughness Fracture Analysis, Davis Besse"3. AREVA NP Document No. 32-9120793-000, "Davis-Besse Unit 1 Upper Shelf Energy Values for 52 EFPY"4. ASME Boiler & Pressure Vessel Code, Section Xl, Division 1, 1995 Edition including 1996 addendum5. AREVA NP Document No. 32-9120525-000, "Davis Besse Unit 1, Reactor Vessel Stress Input for Fracture

Mechanics Analysis"6. Newman, J C, Jr and Raju, I S, "An Empirical Stress Intensity Factor Equation for Surface Cracks",

Engineering Fracture Mechanics, Vol. 5, pp. 185-192, 19817. AREVA NP Document No. 32-1218513-01, "LUS Analysis for Level C & D Loads"8. AREVA NP Document No. 33-1201205-10, "Stress Report Summary for Reactor Vessel"9. AREVA NP Document No. 02-154619E-02, "Detail and Sub-assembly Outlet Nozzle"10. AREVA NP Document No. 02-154620E-02, "Detail and Sub-assembly Inlet Nozzle"11. AREVA NP Document No. 02-154616E-04, "Upper Shell Assembly"12. ASME Boiler and Pressure Vessel Code, Section II, Part D, 1995 Edition with Addenda through 1996.13. AREVA NP Document No. 43-2192PA-000, "Low Upper-Shelf Toughness Fracture Mechanics Analysis of

Reactor Vessels of B&W Owners Reactor Vessel Working Group for Level A&B Service Loads", April 199414. AREVA NP Document No. 32-1206020-00, "RV outlet Nozzle Stress Analysis for LEFM"15. AREVA NP Document No. 86-9025792-001, "Davis Besse Fluence Analysis - Cycles 13-14 Summary

Report"16. AREVA NP Document No. 32-1174278-007, "Verification of PCRIT 6.3 User's Manual"17. AREVA NP Document No. 32-9123247-000, "RTPTS values of Davis-Besse Unit 1 for 52 EFPY, Including

Extended Beltline"18. AREVA NP Document No. 32-9124893-001, "DB-1 Pressurized Thermal Shock (PTS) Analysis for 32 and

52 EFPY"

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APPENDIX A: COMPUTER OUTPUT FILES AND INSTALLATIONNERIFICATIONOF PCRIT

PCRIT was installed and verified for use in the present analysis by executing TestCase 1 and Test Case 2 andcomparing results with those reported in the PCRIT verification package. The output for these two test cases isincluded in the COLDSTOR directory \cold\General-Access\32\32-9000000\32-9110426-000\official. The files arelisted below. The test results are found to be identical to those of Reference [16].

File Name Description Install Date Checksum

DB-LOCA.OUT Hot-leg Loss-of-Coolant Accident 05/26/2010 09622

Test-1 .out Verification. Test Case 1 05/26/2010 10982

Test-2.out Verification Test Case 2 05/26/2010 32526

* Computer program tested: PCRIT 6.3

" Hardware used: Dell Precision 390, Service Tag# / SN: 44HK5D1

" Name of Person running test: S. J. Noronha

" Date of test: 05-26-2010

* Results and applicability: The results in table below are found to be identical to that in PCRITverification report [16].

Stress Intensity Factors, ksirin

Test Case 1 Test Case 2

(longitudinal flaw) (circumferential flaw)

Source Test-1 .out Test-2.out

Deadweight 0 1.09

Residual Stress 9.42 4.98

Pressure 25.65 13.11

Thermal 2.28 21.59

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davis-besse, unit 1, enclosure a to l-12-444, calculation ... · davis-besse nuclear power station,...

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