XGEN-2012-25-NP, Revision 1, 'Westinghouse Engineering ... · XGEN-2012-25-NP February 2013 Revision I. 3-1 3 JET PUMP DESIGN, MATERIAL AND OPERATION Jet pump beams are located at

ATTACHMENT 2

WESTINGHOUSE ENGINEERING REPORT XGEN-2012-25-NP,

REVISION 1, TECHNICAL BASIS FOR THE INSPECTION FREQUENCY

OF THE MODIFIED ALLOY 718 JET PUMP BEAM

(Non-Proprietary)

Nine Mile Point Nuclear Station, LLCMarch 11, 2013

WESTINGHOUSE NON-PROPRIETARY CLASS 3

XGEN-2012-25-NPRevision 1

Westinghouse Engineering Report

Technical Basis for the Inspection Frequencyof the Modified Alloy 718 Jet Pump Beam

Author: Sam Ranganath, XGEN Engineering

Reviewer: Mahadeo Patel, XGEN Engineering

Project Manager:

Product Manager:

Greg J. Gresock*, Project ManagerInvessel Modifications and Repairs

Stephen J. Kaylor*, Product ManagerInvessel Modifications and Repairs

February 2013

*Electronically approved records are authenticated in the electronic document management system.

Westinghouse Electric Company LLC

1000 Westinghouse DriveCranberry Township, PA 16066, USA

© 2013 Westinghouse Electric Company LLCAll Rights Reserved

ii

Revision History

Revision Paragraph Change Description and Reason Engineer ApprovalNumber Number

A Initial Release

B All Sections Incorporate Toshiba review comments S. Ranganath

0 All Sections Incorporate Constellation Energy review S. Ranganathcomments

I All Sections Incorporate Constellation Energy editorial S. Ranganathcomments

XGEN-2012-25-NP February 2013Revision 1

III

TABLE OF CONTENTS

LIST OF TABLES ....................................................................................................................................... iv

LIST OF FIGURES ...................................................................................................................................... v

1 INTRODUCTION ........................................................................................................................ 1-1

2 SUM M ARY .................................................................................................................................. 2-1

3 JET PUM P DESIGN, M ATERIAL AND OPERATION .............................................................. 3-1

3.1 BEAM M ATERIAL ...................................................................................................................... 3-1

3.2 COMPARISON OF MODIFIED ALLOY 718 WITH ALLOY X-750 MATERIAL ................... 3-2

3.2.1 FABRICATION PROCESS ............................................................................................. 3-23.2.2 M ATERIAL COM POSITION ......................................................................................... 3-23.2.3 M ECHANICAL PROPERTIES ....................................................................................... 3-23.2.4 RADIATION INDUCED STRESS RELAXATION ....................................................... 3-23.2.5 FATIGUE INITIATION ................................................................................................... 3-33.2.6 SCC INITIATION ............................................................................................................ 3-33.2.7 SCC CRACK GROW TH ................................................................................................. 3-4

4 ANALYSIS PROCESS & M ETHODOLOGY ............................................................................ 4-1

4.1 ALLOW ABLE FLAW SIZE ......................................................................................................... 4-1

4.2 FINITE ELEM ENT ANALYSIS OF THE JET PUM P BEAM .................................................... 4-1

4.3 LINEAR ELASTIC FRACTURE MECHANICS (LEFM) ANALYSIS OF THE BEAM .......... 4-2

4.4 CRACK GROW TH ANALYSIS .................................................................................................. 4-3

5 DESIGN IN PUTS ......................................................................................................................... 5-1

6 RESULTS ..................................................................................................................................... 6-1

6.1 ALLOW ABLE FLAW SIZE ......................................................................................................... 6-1

6.2 STRESS ANALYSIS .................................................................................................................... 6-1

6.3 FRACTURE MECHANICS AND CRACK GROWTH ANALYSIS .......................................... 6-2

6.4 SUM M ARY OF RESULTS .......................................................................................................... 6-3

7 INSPECTION RECOM M ENDATIONS ...................................................................................... 7-1

7.1 INITIAL INSPECTION CRITERIA ............................................................................................ 7-1

7.2 RE-INSPECTION INTERVALS .................................................................................................. 7-1

8 RE FERENCES ............................................................................................................................. 8-1


iv

LIST OF TABLES

Table 1 Comparison of the Chemical Compositions of Modified Alloy 718 and Alloy X-750 ................ 8-2

Table 2 Influence Coeffi cients for a Surface Crack ................................................................................... 8-3

Table 3 Influence Coefficients for an Edge Crack in a Plate ..................................................................... 8-4

Table 4 Comparison of BWRVIP-138R1 Values and Current Analysis for NMP2 ................................... 8-5


v

LIST OF FIGURES

Figure 1 Jet Pum p Beam Inspection Regions ........................................................................................... 8-6

Figure 2 M odified Alloy 718 Jet Pump Beam .......................................................................................... 8-6

Figure 3 Fabrication Process of Modified Alloy 718 Jet Pump Beam ...................................................... 8-7

Figure 4 Yield and Tensile Strength of Modified Alloy 718 Compared to Alloy X-750 .......................... 8-8

Figure 5 Elongation and Reduction of Area of Modified Alloy 718 Compared to Alloy X-750 .............. 8-9

Figure 6 Stress Relaxation of Alloy X-750 and Alloy 718 in an Irradiated Environment ...................... 8-10

Figure 7 Fatigue Test Results for Modified Alloy 718 and Alloy X-750 ................................................ 8-11

Figure 8 CBB (Creviced Bent Beam) Test Device and Results for Modified Alloy 718 ........................ 8-12

Figure 9 Cross-section of Modified Alloy 718 Test specimen after the CBB test .................................. 8-13

Figure 10 CBB Test Results for Modified Alloy 718, Alloy X-750, and 304SS .................................... 8-13

Figure 11 Chromium Profiles at Grain Boundaries for Modified Alloy 718 and Alloy X-750 .............. 8-14

Figure 12 TEM Photos near the Grain Boundaries of Modified Alloy 718, Conventional Alloy718and A lloy X -750 .................................................................................................................... 8-15

Figure 13 Constant Load Test Results for Modified Alloy 718 and Alloy X-750 .................................. 8-16

Figure 14 Drop-off Time from Maximum Load to 1/2 Maximum Load of Modified Alloy 718 andA lloy-X -750 after Rising Load Test ...................................................................................... 8-16

Figure 15 SCC Growth Rates for Modified Alloy 718 and Alloy X-750 Compared to the BWRVIP-138R 1 R elationship ............................................................................................................... 8-17

Figure 16 Analysis Flowchart for the Toshiba Modified Alloy 718 Jet Pump Beam FractureM echanics Evaluation ............................................................................................................ 8-18

Figure 17 Analysis M odel and Boundary Conditions ............................................................................ 8-19

Figure 18 Postulated Surface Crack ........................................................................................................ 8-20

Figure 19 Crack Growth Rates Used in the Evaluation ............................... 8-21

Figure 20 Maximum Principal Stresses in the Toshiba Modified Alloy 718 Beam ............ ; ..... 8-22

Figure 21 Comparison of Longitudinal Stresses from BWRVIP-138R1 and Present Analysis for theM odified A lloy 718 B eam ..................................................................................................... 8-23

Figure 22 Residual Life Predictions for the Alloy 718 and the X-750 Beams Using the BWRVIP-138R1 N W C Line .......................................................................................................... 8-24

Figure 23 Residual Life Predictions for the Alloy 718 Beam Using Curve A (Factor of 2 lower thanthe BW RV IP-138R1 N W C Line) .......................................................................................... 8-25

Figure 24 Residual Life Predictions for the Alloy 718 Beam Using Curve B (Factor of 10 Lower thanthe BW RVIP-138R1 N W C Line) ........................................................................................ 8-26

XGEN-2012-25-NP February 2013Revision I

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1 INTRODUCTION

Intergranular stress corrosion cracking (IGSCC) failures of Boiling Water Reactor (BWR) jet pumpbeams have occurred in the operating BWR fleet. All the failures have been in Alloy X-750 beams. Thefirst jet pump beam failure was in a BWR/3 plant with the crack starting from the threaded bolt holeregion in the middle of the beam (Inspection Region BB-lin Figure 1). The failure was in the Group 1BWR/3 design beam and the material was Alloy X-750 with the 'equalized and aged' (EQA) heattreatment and the load on the beam was 30 kips. Subsequent failures have also been reported in thetransition region BB-2 in a BWR/6 Group 2 beam in 1993 and in the tapered region BB-3 in a Group 1beam in 2002. The initial industry reaction to jet pump beam cracking was to reduce the beam pre-load to25 kips in all operating plants and over time, to replace the beams with Group 2 beams made of X-750material in the 'high temperature anneal and aged' (HTA) condition. The lower beam pre-load and theuse of the improved HTA treatment has resulted in a reduction in the IGSCC susceptibility of the beam.Other improvements were introduced in the Group 3 design beams in 2001. They included:

1. Use of increased section thickness in the center and the ends to reduce the mean stress2. Use of X-750 material that meets the BWRVIP-84 [1] requirements including the use of the rising

load test3. Elimination of the tack welded keeper

Inspection requirements for the Alloy X-750 jet pump beams were included in BWRVIP-1 38R1 [2] issuedin 2008. The BWR Vessel and Internals Project (BWRVIP) compiled and evaluated information on jetpump beam design and configurations, field experience with cracking, and inspection capabilities. Theyperformed stress and fracture mechanics analyses to determine critical flaw sizes for demonstratingnondestructive evaluation (NDE) techniques and for establishing appropriate inspection intervals. TheBWRVIP also evaluated the benefits of crack mitigation in a HWC environment. BWRVIP-138R1specifies the regions required to be inspected for the bolt hole, tapered section, and beam ends andrecommends base line and re-inspection frequencies for both Group 2 and Group 3 Alloy X-750 beams.

Westinghouse has recently installed new jet pump inlet mixers and jet pump beams at the Nine Mile PointUnit 2 (NMP2). The new jet pump beams are similar in features to the original Group 3 beams but aremade of modified Alloy 718 and have minor dimensional differences when compared to the Group 3beams they were replacing. Since the new beams at NMP2 are different than the X-750 beams coveredby BWRVIP- 13 8R 1, new evaluations are required to develop base line and re-inspection requirements.Specifically, the purpose of the new evaluation is to: i) perform crack growth evaluation for modifiedAlloy 718 jet pump and ii) specify recommended inspection intervals based upon the jet pump beam flawtolerance. This report describes the stress and fracture mechanics analyses to determine the allowableflaw sizes. Crack growth analysis is performed for IGSCC using specific data for the modified Alloy 718(used for the NMP2 beams) in the BWR environment. Based on the analysis described here,recommendations for the initial base line inspections and re-inspections are made in this report.


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2 SUMMARY

This report provides inspection recommendations for the Toshiba modified Alloy 718 jet pump beam

installed at NMP2. The recommendations follow the technical approach used in BWRVIP-138R1 andconsider the SCC susceptibility of modified Alloy 718 material when compared to that of Alloy X-750.The comparison of modified Alloy 718 with Alloy X-750 addresses a variety of factors - fabricationprocess, material composition, mechanical properties, stress relaxation, fatigue initiation. Thecomparison shows that in all cases, modified Alloy 718 is as good as or better than Alloy X-750 underBWR operating conditions. In two other important areas - SCC initiation and SCC crack growth -modified Alloy 718 is significantly better than X-750. The superiority of modified Alloy 718 in terms of

SCC resistance has been confirmed by a variety of SCC initiation tests including creviced bent beam(CBB), constant load and rising load tests as well as crack growth tests. Based on the lower steady statestress in the modified Alloy 718 and the favorable SCC initiation test data, the probability of SCCinitiation is judged to be extremely low. Even if crack initiation does occur, the time period for adetectable initial flaw to propagate to the allowable flaw size is in excess of 45 years. Based on this, onecan make the case that no in-service inspections are required at all. Nevertheless, a more conservativeapproach consistent with BWRVIP-1 38R1 and accounting for the improved SCC properties of themodified alloy 718 material is followed here in setting the inspection schedules for the Toshiba beam.With additional field experience, the inspection recommendations may be revised at a later date. Thefollowing inspection schedule is recommended for the Toshiba modified Alloy 718 jet pump beaminstalled at NMP2:

Initial baseline inspection is recommended 24 years after installation. This recommendation isapplied conservatively for the three inspection regions (BB-1, BB-2 and BB-3) of the beam andcovers both Normal Water Chemistry (NWC) and Hydrogen Water Chemistry (HWC) operation.

A conservative re-inspection interval of 16 years is recommended for the three inspection regions(BB-1, BB-2 and BB-3) of the beam for both NWC and HWC conditions.


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3 JET PUMP DESIGN, MATERIAL AND OPERATION

Jet pump beams are located at the top of the inlet mixer assembly and are used to mechanically lock theinlet mixer to the riser pipe transition piece. The jet pump beam is deflected during installation to providea preload of approximately 25,000 pounds on the jet pump. It is hydraulically deflected while in placeabove the jet pump assembly, and is fixed in the preloaded condition via a bolt that is integral to the jetpump beam. The bolt is threaded through the jet pump beam and contacts the top of the jet pump. Aftercontact, the bolt is loaded to a predetermined torque value through a given angular rotation. An iterativeprocess is used and both the torque and the rotation are monitored to verify that the jet pump beam andinlet mixer are properly seated. After the beam is tensioned, an integral locking device engages aroundthe bolt and prevents it from loosening. This in turn prevents the beam from losing preload.

The load path in the jet pump beam starts with a vertical force applied to the jet pump beam bolt hole bythe beam bolt and ends in the force being reacted by the hold down brackets on the transition piece. Ahydraulic tensioner is used to load the beam and when the specified tensioner pressure is reached thebeam bolt is then advanced down until it contacts the seat in the transition piece. The tensioner is thendepressurized and removed from the assembly. The jet pump beam remains in position with adisplacement induced load. As the reactor reaches operating temperature, because of the reduction in theelastic modulus of the beam material, the load on the jet pump beam in the operating condition is reducedby the ratio of the elastic moduli at installation temperature and at operating temperature. For the Alloy

.718 material, the elastic modulus at 100°F is 28.8x10 6 psi and the corresponding value at 550'F is27.Ox 106 psi. Effective load in the operating condition is given by:

Effective Load = Installed load at I 00°F* (278.x1°6 = 0.938(Installed Load)•28.8x106 )'098Istle od

For very deep flaws the stiffhess of the jet pump would decrease which in turn would reduce the retainedmechanical preload until it equaled the hydraulic load acting on the transition piece. At this time the beamwould experience the hydraulic load and the load would transition from displacement controlled to load

controlled.

3.1 BEAM MATERIAL

The original jet pump beam was fabricated from Alloy X-750 in the HTA condition. Although stresscorrosion cracking (SCC) susceptibility of Alloy X-750 was reduced by decreasing the load and bymodifying the heat treatment, SCC failures of Alloy X- 750 jet pump beams have occurred in BWRplants. The material chosen, along with the geometry of the beam (that results in higher stresses comparedto that in the Toshiba beam), makes the original beam susceptible to SCC failure. The Toshiba-designedjet pump beam installed at NMP2 (Figure 2) is an improvement over the existing X-750 beam design.Toshiba has developed a modified heat treatment Alloy 718 which has greater material reliability thanalloy X-750, the original beam material. Compared to X-750, the modified Alloy 718 beam has greaterSCC resistance, higher ductility, and superior fatigue and spring properties. Its high strength and hardnessare similar to that of Alloy X-750, allowing it to meet the requirements of bolting materials. In addition,Toshiba adjusted the beam geometry to minimize stresses under the preloaded condition. The Toshiba JPbeam was also improved by the implementation of a newly-designed integral ratchet locking device. Thisdevice eliminates the need to tack weld the beam bolt, which reduces outage duration and risk.


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Clearly, the combination of material choice and geometry improvements reduce the Toshiba beam'ssusceptibility to IGSCC.

3.2 COMPARISON OF MODIFIED ALLOY 718 WITH ALLOY X-750 MATERIAL

This section provides a comparison of the modified Alloy 718 used in the NMP2 beams with the Alloy X-750 used in the original beams. The mechanical properties (yield and ultimate strength and percentreduction in area), material composition, radiation induced stress relaxation, fatigue initiation, SCCinitiation (steady state loading vs. time to crack initiation in the environment) and SCC crack growth ratein the normal water chemistry BWR environment. The comparison shows that the modified Alloy 718has superior or comparable properties when compared to the original beam material, Alloy X-750.

3.2.1 Fabrication Process

Figure 3 shows fabrication process of modified alloy 718 jet pump beam. Remelt processes such asvacuum induction melt (VIM) and vacuum arc remelt (VAR) are applied to modified alloy 718 jet pumpbeam. The 6-phase formed during hot forming is dissolved by solution heat treatment atl0300C(1886°F). There is no difference in fabrication process between modified alloy 718 and Alloy X-750 jetpump beams except for heat treatment conditions. Grain size can be controlled within a range of No.3 toNo.5 (ASTM grain size number).

3.2.2 Material Composition

Table I shows a comparison of the chemical compositions of the modified Alloy 718 and the originalbeam material Alloy X-750. Other than the requirement to minimize the Cobalt level, the chemicalcomposition of modified Alloy 718 is the same as that of conventional Alloy 718 specified with ASMESB-637 alloy UNS N07718.

3.2.3 Mechanical Properties

Figures 4 and 5 show comparisons of the yield strength, ultimate tensile strength, percent elongation andpercent reduction in area respectively, for the modified Alloy 718 and the original beam material Alloy X-750. In general the results are consistent with ASME X-750 SB-637 Alloy N07750 requirements. Theductility properties of the modified Alloy 718 (as measured by the uniform elongation and percentreduction in area) exceed the ASME requirements and the expected values for Alloy X-750.

3.2.4 Radiation Induced Stress Relaxation

The jet pump preload is expected to relax with exposure to the neutron flux in the annulus. As shown inFigure 6, [3] Alloy 718 has similar radiation relaxation rates in comparison to alloy X-750. Since there issufficient field experience indicating that the expected preload loss with radiation is acceptable for the X-750 beams, it stands to reason that the modified Alloy 718 will also be acceptable, from the viewpoint ofradiation induced stress relaxation.


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3.2.5 Fatigue Initiation

Figure 7 shows the comparison of the fatigue test results in air for modified Alloy 718 and Alloy X-750.The fatigue strength of Alloy 718 is slightly higher than that of Alloy X-750 in the high cycle (> 105cycles) region of the fatigue curve. The overall results for both materials are consistent with the ASMECode fatigue design curve. Fatigue property in air was evaluated by testing under a cyclic load condition.

3.2.6 SCC Initiation

A significant feature of the modified Alloy 718 material is the higher resistance to SCC initiation in hightemperature BWR water environment. Creviced Bent Beam (CBB) tests were used to evaluate the SCCresistance of modified Alloy 718, in comparison with Alloy X-750 and sensitized Type 304 stainless steel.The CBB test (commonly used to assess SCC susceptibility) uses specimens (50 mm x 10 mm x 2 mm)bent along the device with the curvature of 100 mm in radius. This results in a constant strain of 1% onthe outer surface of the specimens. Graphite wool, the material chosen to form the crevice is attached tothe outer surface of specimens and the test specimens are exposed to the high temperature water (288'C)for 500 hours in an autoclave installed with a recirculating loop. Figure 8 shows a schematic of the CBBtest and the CBB test results of modified alloy 718 in 288'C pure water (20 ppm 02). No cracking wasobserved in any of the five Alloy 718 specimens tested, whereas 2 out of 3 reference specimens(sensitized Type 304 stainless steel) experienced cracking. Figure 9 shows the cross-section of modifiedalloy 718 test specimen after the CBB test. The extremely low SCC susceptibility of modified Alloy 718is particularly clear when the CBB results of modified Alloy 718 are compared to those of alloy X-750and sensitized type 304 stainless steel (Figure 10).The figure shows SCC crack depth of modified alloy718, alloy X-750, and after CBB test in high temperature water with various chloride contents (288°C, 8ppm 02). Alloy X-750 is most susceptible to SCC in almost the entire range of chloride contents, next issensitized type 304stainless steel. Modified alloy 718 is nearly immune to SCC in the range of less than50 ppb of chloride content. Figure 11 shows the chromium profiles perpendicular to the grain boundariesof modified alloy 718 and alloy X-750. Figure 12 shows the Transmission Electron Microscope (TEM)photos near the grain boundaries of the modified Alloy 718, and Alloy X-750. No precipitate is visible onthe grain boundaries of the modified Alloy 718 and conventional Alloy 718. However, large chromiumcarbides form on the grain boundary of alloy X-750. Modified Alloy 718 and conventional Alloy 718have no chromium depletion similar to that observed in Alloy X-750.

Another common test to evaluate SCC susceptibility is the constant load test. A uniaxial constant load(UCL) test was conducted using the modified Alloy 718 and Alloy X-750 to evaluate resistance to SCCinitiation in high temperature water. The specimen was tested under constant load in an autoclaveequipped with a high temperature water loop (288°C, 8 ppm 02). Graphite wool was used to create acrevice around the gage section of the specimen. Figure 13 shows the applied stress vs. time to crackingfor the modified Alloy 718 and Alloy X-750 from the constant load tests. Tests of modified alloy 718were conducted for 10,000 hours. Modified alloy 718 showed no failure for 10,000 hours at applied stressbeyond the yield strength (700-800 MPa in 288°C). It is clear that modified Alloy 718 has excellentresistance to high temperature SCC and is superior to Alloy X-750 from the SCC viewpoint.

BWRVIP-84R2 requires rising load testing to be performed in accordance with MIL-DTL-24114F (SH)Appendix A to verify that the required heat treatment has been performed properly for the Alloy X-750material. Although a similar requirement does not apply for Alloy 718, Toshiba has compared the results


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of the rising load test for both the modified Alloy 718 and Alloy X-750. The specimens were notched andsubsequently pre-cracked. The specimens were then tested under three-point bending load with aconstant displacement rate (0.002 inch per minute) loading in aerated 200'F (93'C) water (deionizedwater). The BWRVIP-84 acceptance criterion is that the average drop-off time from maximum load to 1/2maximum load shall be equal to or greater than 4 minutes and that no specimen shall display a value lessthan 2 minutes. Figure 14 shows that the drop-off meets the requirement for both Alloy X-750 andmodified Alloy 718, but the time for modified Alloy 718 is about 15 times longer than that of Alloy X-750 confirming that modified Alloy 718 has excellent resistance to low temperature SCC also.

3.2.7 SCC Crack Growth

Resistance to SCC propagation in high temperature water was evaluated by crack growth rate test using a0.5TCT specimen loaded at stress intensity factor (K) values ranging from 30- 60 MPa-Vm(27-55 ksiVin).The crack length was monitored by means of the reversing DC potential drop method (PDM). The testwas performed under normal water chemistry (NWC) conditions in an autoclave installed in arecirculating loop. Figure 15 shows the SCC growth rate as a function of applied K for both the modifiedAlloy 718 and Alloy X-750. SCC growth rate data for both Alloy X-750 and the modified Alloy 718 fallbelow the proposed curves in BWRVIP- 13 8R 1. However, the SCC growth rate for the modified Alloy718 is significantly lower, over two orders of magnitude lower than that specified in the BWRVIP-138R1relationship for NWC.

XGEN-2012-25-NP February 2013. Revision 1

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4 ANALYSIS PROCESS & METHODOLOGY

The process used in this report to perform the evaluation and the technical bases for the methods usedhere are virtually identical to that described in BWRVIP-138R1. The only differences in input are in thedesign and material specific properties of the modified Alloy 718 beam used at NMP2. As described inSection 3, extensive testing was performed to qualify the modified Alloy 718 material. The heat number ofthe test materials differed from that used for the NMP2 JP Beams, but the fabrication process and chemicalcomposition of the test material and the NMP2 beam material were identical. The flow chart shown in Figure 16shows each step in the process used to assess the flaw tolerance of the jet pump beam. The methods usedfor each step are discussed in this section.

4.1 ALLOWABLE FLAW SIZE

The jet pump beam is fabricated from modified Alloy 718; because of the high ductility of the Alloy 718material, plastic collapse (or limit load failure) in shear is the governing failure mechanism. Theallowable flaw size is determined by solving for the un-cracked ligament required to react the shear loadapplied to the jet pump beam. The average shear stress in a rectangular section with an edge crack isgiven by:

FT = (1)Be

where F is the shear force (equal to half the force on the beam), B is the width of the beam and 9 is theuncracked ligament thickness. As described in BWRVIP-138R1, the force on the beam is the hydraulicload. The beam preload is displacement controlled and is relieved at the point of collapse. On the otherhand, the hydraulic load is primary and can contribute to the limit load failure. The shear load is one halfof the force on the beam.

The required ligament thickness is given by:

e= SF - (2)BTf

where SF is the structural factor assumed to be 3 (to be consistent with the ASME code) and Tf is the flowstress in shear. The flow stress in shear is equal to half the flow stress in tension. The flow stress isapproximated by averaging the yield strength Sy and the ultimate strength Su:

S(S+Sy (3)

The ultimate strength, Su of Alloy 718 at 550'F is 160 ksi and the yield strength Sy is 90.7 ksi. The flowstress in tension is 125.3 ksi and the corresponding value in shear is 62.7 ksi.

4.2 FINITE ELEMENT ANALYSIS OF THE JET PUMP BEAM

A three-dimensional finite element model was developed using the ANSYS finite element code. Themodel was made with linear 3-D solid elements. The model, applied load and boundary conditions are


4-2

shown in Figure 17. As described in BWRVIP-138R1, there is very little change in compliance for thetype of shallow surface cracks used in the fracture mechanics analysis. Therefore the stress analysis wasbased on a single load application on the uncracked beam. As stated in Section 2, the load relaxation dueto temperature was included by multiplying the as-installed load by the ratio of the elastic modulus at theoperating temperature and the installation temperature (100'F) in the FEM analysis. The retained boltpreload at installation temperature used in BWRVIP-138R1 was based on a GEH internal test reportdocumenting load testing of the jet pump beam. For this analysis, it was assumed conservatively that theretained load is equal to the as-installed pre-load on the beam.

4.3 LINEAR ELASTIC FRACTURE MECHANICS (LEFM) ANALYSIS OF THEBEAM

BWRVIP-I 38RI considered several cracks - center crack and corner cracks at the transition region (BB-2) and in the tapered region (BB-3) and the corner crack near the between the hole and the handle (BB-3)- and evaluated the residual life as a function of crack depth for all these cases. The residual life was thelowest for a postulated center crack in the transition region. Therefore, the crack configuration selectedfor the bounding analysis is a center surface crack at the highest stress location (Section B in Figure 18) inthe BB-2 region. Figure 18 shows the postulated surface crack. Using the same approach as in BWRVIP-138R1, the initial crack is assumed to be a semi-circular surface crack of depth 'a' and length '2c'(initially a=c) as shown in Figure 18. The stress intensity factor is calculated at the crack tip at thedeepest point on the crack (Point 1 or p= 90* in Figure 18) and on the surface (Point 2 or 9=0' in Figure18). Since the stress intensity factors at Points I and 2 are different, the associated crack growth rates arealso different. The increments in crack depth, Aa and crack half-length, Ac are therefore different. Thecrack shape which starts as a semi-circle becomes semi-elliptical over time since the crack growth at thesurface (Point 2) is somewhat higher than that at the deepest part (Point 1). Eventually, the crack lengthcovers the entire width of the beam. At this point, the crack is evaluated as an edge crack. Figure 18shows the sequence over which a semi-circular surface crack grows into an edge crack.

The stress intensity solution API 579 [4] for a semi-elliptic surface crack under a fourth order polynomialfit stress distribution was used for the K calculation. The stress distribution is represented as a fourthorder polynomial as follows:

orx) = a0 + a., (t) + '72 ()+ 0'3 ()+ C7(t4 (4)

where x is the distance from the surface with the crack and t is the thickness of the plate and o0,0Fl,02, 03 and 04 are the coefficients to the fourth-order polynomial fit to the stress distribution.

The stress intensity factor is given by:

K, =[GO.70 + Glo1 -~) -+ G2ey2 (1)2+G 3 ( + G + Q~4 ()4 I (5)


4-3

where Go, G1 , G20 , G3 and G4 are functions of (t)and (1) and 1 = 2c. The equations to determine Go, G1 ,wher

G20 , G3 and G4 are given in Table 2. Q is the flaw shape factor given by:

Q =[1 + 4 .59 3 () -qy] (6)

qy [(Go0o + Glaa + G2 o2 + G3 U3 + G4 a4)/Sy]2 /6 (7)

where Sy is the yield strength

The finite width correction factor f, is given by:

sec (,J )0 (8)

where, 2W = B = width of the beam.

The above equations are valid as long as the length 2c, of the surface crack is less than the width of thebeam (see Figure 18). When the length is equal to the width, it is treated conservatively as an edge crackof depth, a in a plate. Essentially it is the same solution as for a surface crack, but the length is assumedto large compared to the depth, i.e. 2c >> a. The stress distribution is the same as that assumed inEquation 4.

The stress intensity factor for an edge crack is given by:

K, =[Gooro + Glcr1 -) + G~c 2 () + G3U3 (t)3 + G~ (t)]vri~a (9)

When performing crack growth analysis starting with a shallow semi-circular crack, the solution inEquation 4 is used, but when the length of the crack is equal to the width of the beam, then the solutionfor the edge crack in Equation 9 will be used.

4.4 CRACK GROWTH ANALYSIS

Figure 19 shows the recommended crack growth rates (CGR) for X-750 in normal water chemistry(NWC) and hydrogen water chemistry (HWC) environments as well as the recommended crack growthrates for modified Alloy 718 for both NWC and HWC proposed by Toshiba. It is seen that the Toshibarecommended crack growth rates (Curve C in Figure 19) are two orders of magnitude lower than that forX-750 under NWC. The low CGRs also reflect the inherent resistance to SCC initiation discussed inSection 3.2. Nevertheless, a more conservative approach consistent with BWRVIP- 138R1 andaccounting for the improved SCC properties of the modified alloy 718 material is followed here. Two

conservative CGR relationships are used:

1. Alloy 718 CGR that is a factor of 2 lower than that of the BWRVIP-138R1 relationship for X-750under NWC (Curve A in Figure 19). This is the same as the CGR in BWRVIP-138R1 for X-750


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under HWC. Like the CGR models in BWRV1P-138R1, there is an upper bound plateau, but nolower bound.

2. Alloy 718 CGR that is a factor of 10 lower than that of the BWRVIP-138R1 relationship for X-750 under NWC (Curve B in Figure 19). There is an upper bound plateau, but there is also lowerbound plateau (2E-12 m/s or 2.835E-7 in/hr).

Both Alloy 718 CGR relationships are shown in Figure 19. They are very conservative when compared tothe Toshiba recommended line. The Curve A recommendation in is 64 times higher than that in the CurveC Toshiba line whereas Curve B is a factor of 12.8 higher than that in the Toshiba line. Clearly, both linesare conservative. Furthermore, the same line is used for both NWC and HWC which makes it even mostconservative for BWRs that run with HWC.


5-1

5 DESIGN INPUTS

The design assumptions used in the jet pump beam analysis are similar to those used in BWRVIP-38R1with some minor changes:

1. All LEFM and limit load analyses are performed using the as-installed load of 25 kips (withcorrection to account for the temperature in the operating condition). The retained load in thebeam (due to load sharing with the support after preloading) is slightly lower than the 25-kipvalue, but the analysis is performed assuming conservatively the design value of 25 kips.Reduction in beam pre-load due to radiation induced relaxation is conservatively ignored.

2. Initial flaw size is assumed to be 0.01 in x 0.02 in (a x 2c) for the semi-circular flaw.

3. All postulated cracking is assumed to remain planar. In other words, the crack front willnot change direction as the flaw grows through the section.

4. The method for transitioning a center crack to an edge crack is to define the edge crackdepth equal to the deepest part of the center crack at the time that the crack breaksthrough to the sides of the beam (see Figure 18). This conservative approach does nottake credit for the time it takes for the edges of the flaw to grow in depth to a trulyrectangular shape

5. As described earlier, the hydraulic load (primary) is used for the allowable flaw size, butthe SCC crack growth analysis is performed for the 25-kip as-installed load(displacement controlled secondary load).

Table 4 shows a comparison of the design inputs used in the current analysis of the Alloy 718 beam withthose used in BWRVIP-138R1 for the Alloy X-750 beam.


6-1

6 RESULTS

This section presents the results of each step of the evaluation. The following items are presented below:

* Allowable Flaw Size* Stress Analysis* Fracture Mechanics and Crack Growth Evaluation

6.1 ALLOWABLE FLAW SIZE

As shown in Section 4.1 the required ligament thickness is: e = SF FBerf

The width B, of the beam is 40.5 mm = 1.594 in., the shear force F is one-half of the hydraulic load = 6kips, the flow stress in shear = Tf = half the flow stress in tension = 125.3/2=62.7 ksi and the structuralfactor, SF = 3. Substituting these values, the required ligament is 0.18 inches.

The thickness at the Section B in the transition region BB-2 is 30 mm = 1.181 in. The allowable flaw size= 1.181-0.18 = 1.001 in.

6.2 STRESS ANALYSIS

The stress analysis was performed using methods similar to that used in BWRVIP-138R1. As describedin Section 4.2, the stress analysis was based on a single load application on the uncracked beam. Figure20 shows the maximum principal stresses in the Toshiba modified Alloy 718 beam. It is seen that themaximum principal stress in the beam is 42.3 ksi (291.7 MPa). It is well below the range shown inFigure 13 where cracking was observed in Alloy X-750 (no cracking was observed in the Alloy 718 data).

Per BWRVIP-84R2, the sustained stress level under normal operating conditions for any component madeof X-750 shall not exceed 70% of the ASME Code orCMTR minimum yield strength of the material atthe intended operating temperature for a 40-year design (78% for threaded connectors). BWRVIP-84R2states that:

"Testing has shown that Alloy 718 has superior crack initiation and crack growth ratecharacteristics when compared to X-750.However sufficient test data are not currently availableto fully characterize crack initiation as a function of applied stress with any statisticalsignificance. Until such data are available, the stress limitations shown here, which weredeveloped for X-750, will be conservatively applied to Alloy 718."

The stress ratio (ratio of the applied stress to the yield strength) is 42.3/90.7 = 0.466 which is well belowthe allowable value for 40-year operation. It is therefore expected that the time to crack initiation (if itoccurs at all) in the Alloy 718 beam is well in excess of 40 years.

Crack growth of a flaw (Section B) in the BB-2 region is a function of the longitudinal stress. FEMresults for the longitudinal stress were plotted so that the stress intensity factors could be determined forthe crack growth analysis. Figure 21 shows the longitudinal stress plot as well as the stress as a function


6-2

of crack depth. The figure also includes the results for the Group 3 beam shown in BWRVIP-138R1 forthe same location. It is seen that the maximum longitudinal stress (45.7 ksi) is higher in the originalequipment beam (evaluated in BWRVIP-138R 1) when compared to the maximum longitudinal stress(38.8 ksi) in the modified Alloy 718 beam. However, when the stress results for Section B are compared,the magnitudes as well as the distribution through the thickness are very close. This suggests that for thesame crack growth rate assumptions, the predicted crack growth should be comparable.

6.3 FRACTURE MECHANICS AND CRACK GROWTH ANALYSIS

Crack growth evaluation was performed in the following manner:

1. Assume an initial flaw size, typically 0.01" x 0.01"

2. Calculate K, at the crack tip on the surface (point 2 in Figure 18) and at the deepest point (point Iin Figure 18).

3. Calculate the incremental crack growth on the surface Ac at each crack tip, and theincremental growth in depth Aa, direction using the K, values from step (ii) and theappropriate crack growth rate from Figure 19.

4. Increment the crack size by the Aa and Ac calculated in step (iii). As stated earlier, thelength growth rate is somewhat higher than the depth growth rate, so the flaw whichstarts as a semi-circle becomes semi-elliptical with crack growth.

5. Iterate steps (ii) through (iv) until the crack reaches the allowable flaw size. When thecrack length 2c equals the width of the beam, the stress intensity solution changes fromthat of a surface flaw to that for an edge crack.

Crack growth evaluation was performed using three different crack growth relationships.

Case 1: This case considers crack growth using the BWRVIP-138R1 NWC IGSCC crack growthrelationship for Alloy X-750. Since the stress distribution in Section B in the current analysis andthe BWRVIP-138R I are very close (Figure 21), it is reasonable to expect that the predicted growthwould be similar. Since the analysis in BWRVIP-138R1 was performed using the GE CodePROPLIFE and the current analysis is performed using the API 579 solution, the objective of thiscase is to compare and benchmark the two predictions.

Case 2: This case considers the crack using Alloy 718 specific crack growth rates. This case usesCurve A in Figure 19 which represents a factor of 2 on the BWRVIP-138R1 NWC IGSCC crackgrowth relationship for Alloy X-750. This case is extremely conservative since the Toshiba CGRdata for modified Alloy 718 is well below that for Alloy X-750.

Case 3: This case uses Curve B in Figure 19 which represents a factor of 10 on the BWRVIP-138R1 NWC IGSCC crack growth relationship for Alloy X-750.


6-3

Case 1 Results

Figure 22 shows a comparison of the residual life as a function of initial crack depth, a, and initial crackhalf-length, c, for the modified Alloy 718 beam using the BWRVIP-138R1 NWC IGSCC crack growthrelationship. The prediction from BWRVIP-138R1 for the original X-750 beam is also shown. There isgood agreement between the two models confirming that that the present analysis based on the API 578solution is consistent with BWRVIP-138Rlwhich was based on the GE Code PROPLIFE.

Case 2 Results

Figure 23 shows the residual life as a function of initial crack depth, a, and initial crack half-length, c, forthe modified Alloy 718 beam using Curve A which is a factor of 2 lower than the BWRVIP-138R1 NWCIGSCC crack growth relationship. It is seen that the for a given assumed flaw size, the residual life isalmost twice as large as that in BWRVIP- 138R1 even with a very conservative crack growth rateassumption for Alloy 718. Specifically, for the 0.01 inch semi-circular flaw assumption, the residual lifeis over 45 years. Clearly, this is a significant improvement over the results in BWRVIP-138R1 for theAlloy X-750 beam. Considering that Curve A is a factor of 64 over the Toshiba data and therecommended line, the Case 2 analysis is very conservative and still supports operation of 45 years for the0.01 inch initial flaw.

Case 3 Results

Figure 24 shows the residual life as a function of initial crack depth, a, and initial crack half-length, c, forthe modified Alloy 718 beam using Curve B which is a factor of 10 lower than the BWRVIP-138R1NWC IGSCC crack growth relationship. It is seen that for a given assumed 0.01-inch initial flaw size, theresidual life is in excess of 90 years. Since Curve B is still a factor of 12.8 over the Toshiba data and therecommended line, a case can be made that inspections are not necessary at all based on the results shownin in Figure 24.

6.4. SUMMARY OF RESULTS

The fracture mechanics and crack growth evaluation described here provide the residual life as a functionof initial flaw size for the Crack plane B in the inspection region BB-2. The focus of the analysis was onthe BB-2 region since the BWRVIP- 138R 1 analysis indicated that the transition region near the beamsupport in inspection region BB-2 was limiting. These results can be used to develop base line inspectionand re-inspection periods for the modified Alloy 718 beam.


7-1

7 INSPECTION RECOMMENDATIONS

The inspection recommendations provided here follow the technical approach used in BWRVIP- 138R 1and consider the SCC susceptibility of modified Alloy 718 material when compared to that of Alloy X-750. The comparison of modified Alloy 718 with Alloy X-750 discussed in Section 3.2 address a variety

of factors - fabrication process, material composition, mechanical properties, stress relaxation, fatigueinitiation - and in all cases, modified Alloy 718 is as good as or better than X-750 under BWR operatingconditions. In two other important areas - SCC initiation and SCC crack growth - modified Alloy 718 issignificantly better than X-750. The superiority of modified Alloy 718 in terms of SCC resistance hasbeen confirmed by a variety of SCC initiation tests including creviced bent beam (CBB), constant loadand rising load tests as well as crack growth tests. Based on the steady state stress in the modified Alloy718 and the SCC initiation results, the probability of SCC initiation is extremely low. Even if initiationdoes occur, the time period for a detectable initial flaw to propagate to the allowable flaw size is in excessof 45 years. Based on this, one can make the case that no in-service inspections are required.Nevertheless, a more conservative approach, consistent with BWRVIP-138R I and accounting for theimproved SCC properties of the modified alloy 718 material, is followed here in setting the inspectionschedules for the Toshiba beam. With additional field experience and more test data, the inspectionrecommendations may be revised at a later date.

7.1 INITIAL INSPECTION CRITERIA

The initial inspections recommended here are based on the limiting BB-2 region, but can be appliedconservatively to the BB-1 and BB-3 regions also. BWRVIP-138R1 recommends initial baseline

inspection in the Group 3 Alloy X-750 beams after 20 years. Since the sustained stresses in the Toshibabeam are somewhat lower than that for the original Type 3 beams, and the SCC resistance of the modifiedAlloy 718 is far superior to that of X-750, the initial baseline inspection is recommended 24 years afterinstallation. This recommendation is applied conservatively for all regions and covers both NWC and

HWC operation. The inspection regions and the inspection methods should be similar to thoserecommended in BWRVIP- 1 38R1.

7.2 RE-INSPECTION INTERVALS

BWRVIP- 138R1 recommends re-inspection of all regions of the beam every 8 years for NWC and every12 years for HWC for all Type 3 X-750 beams. Longer inspection intervals can be justified for the Alloy718 beams based on the residual life estimated in this report. For example, even with the conservativeCurve A assumption a residual life of 20 years can be justified for 0. 1-inch deep flaw. A conservative re-inspection interval of 16 years is recommended for all regions of the beam for both NWC and HWCconditions.


8-1

8 REFERENCES

1. BWRVIP-84 Revision 2: BWRVIP Vessel and Internals Project, Guidelines for the Selection and Useof Materials for Repairs to BWR Internal Components. EPRI, Palo Alto, CA: 2012. 1026603.

2. BWRVIP-138, Revision 1: BWR Vessel and Internals Project, Updated Jet Pump Beam Inspectionand Evaluation Guidelines. EPRI, Palo Alto, CA: 2008. 1016574.

3. Jet Pump Beam Fabrication - Comparison of Modified Alloy 718 and Alloy X750 Materials,Westinghouse ReportTR-MODS-1 1-4, Revision 1, December 2011.

4. API Recommended Practice 579, "Fitness for Service", First Edition, American Petroleum Institute,Washington, D.C.


8-2

Table 1 Comparison of the Chemical Compositions of Modified Alloy 718 and Alloy X-750

Weight Percent

Element Modified Alloy 718 (Note 1) Alloy X-750 (Note 2)

C 0.08 max. 0.08 max.

Mn 0.35 max. 0.35 max.

Si 0.35 max. 0.50 max

S 0.015 max. 0.01 max.

P 0.015 max.

Cr 17-21 14-17

Co 0.2 max.(Note 3) 1.0 max

Mo 2.8-3.3

Cb (Nb)+Ta 4.75-5.50 0.70-1.20

Ti 0.65-1.15 2.25-2.75

Al 0.2-0.8 0.40-1.00

B 0.006 max.

Fe Remainder 5.00-9.00

Cu 0.3 max. 0.50 max

Ni 50-55 70.0 min

Note 1: Designation ASME/ASTM SB-637/B637 Alloy UNS N07718 (Grade 718)

Note 2: Designation ASME/ASTM SB-637/B637 Alloy UNS N07750 (Grade 688)

Note 3: The maximum cobalt content shall be 0.20%. Alternatively, if it is not practicable to procure the material for individualcomponents to this requirement, a maximum allowable weighted average cobalt level of 0.25% is permissible.


8-3

Table 2 Influence Coefficients for a Surface Crack

C c

t

W W

(a) Finite Length Surface Crack

Whi m w Ce o.fhls1 Fer A Pilt t Langl h tl, ,e. Cydk in A PN i.

Cp ce C, C2 C) C, CC , C C, co co Co

0.0 Ge .236 47960 4-671 1.461 M7226 0.160 0.84360 -1.733 .2.? 0.6866 49480

0.0500 -1.1022 40.03W2 0.200 0.8AM 0.10960 0.0641 -3.10"7 463066 2A4443 0.186M7

02.0 6 .1.481 4016.om 1 4 62 5 0.1 m 0.041 o.1 .16,m48 422151 2.952 0.18M

0) 7.3661. .1.154"4 4=36I4 4*M173 0.04633 0.44640 6.66404 -1.466 -061464 5.062 0.10436

0 4 0-10 3 • 1.2132 4 .% 04 8 23 &020326 0C 6 4 4.10A 2 , -.1.1612 -03346 3 ,2003 0.0746 0

600 0G 076 61 0.041621 48m18 0oj4i72 4.336 0a .6267 46F361 4064836 025nm .422606 -

0.13407 0.03 i018 0.14706 0.15 1 0.048865 0.1676 -0.12106 7200#4 0.003076 ,.064413 -

0, 0.760 1.6O360 0OW7N 0.0266 112715 0.0660 0.012227 0.02160 0.041600 .0.061236 -

0 o -• i 4 0.3In .03M 0.1360 O.62 0.720 026 0.0227m6 C0OM0 -

G 4 0 3 6 -4676t 0m , 3 0 4 o2 0.0 6147 o 0.o 6 0. 01 4 21M -

1. Th @*Aon Io demin knwwe coullol 1 fOr - 0s show bow.

q+, 4(, +C.(-J+ C6(!J) +q 4a) +Cma)(G,

1.0 + C,( 2Cj)+C{a) +,(a +,(aJ.(a)2. Theequdmiolo dslinul .ncoeffcMW le r ip m 901e fho below

-4 +~4~+ 4h{') (2 + c.4[a)J + q(d ). a ) ++ 4'{.+.)J + q~(!,)t{..] + 7 u;! [{J


8-4

Table 3 Influence Coefficients for an Edge Crack in a Plate

Ix

l t

(b) Infinitely Long Surface Crack (c>>a)

Tabb C.IhMus Ces•dhah FPorA a•h, Luu 8 a ias h A M m (1)

M Go 0_ 0a Go 0_

0.0 1.1200 o.662o o.64m oA404 0.3791O.1 1.1604 o.706 0.6m2 oA473 0.3om60.2 t.3667 0.7732 0.753 0.4741 0.4043

0.4 2.0l 0 1.06m 0.7286 0741 0A790.6 4A0M 1.7480 1.009 0.8121 0.626

OA 11.8m27 4.4702 2.6244 1.7009 1 .2754

flume Cesfoumu m hin Euals Pom (2)

C, C, C2 C, C,

O#1,t12 6.061 -1.3661 7la0w0 31014

0, 0.66106 2.31t37 -0.7169 3.1140 10.702

0, O.8l20 1.3001 -G0AM11 2.1413 6L00M

Oj 042070 0.673 26-O.M07 1.7131 21443

04 0.361 04619 -.0.26777 0A7481 2.2063

1. fiuem-mn may be uNd for I umsdI I vkma of a/l.2. The quslan i dsun Inr u .oeoom Mm' I dism .

0, - C6, +(a)2 + C2! + Cf + C4( (C.313)


8-5

Table 4 Comparison of BWRVIP-138R1 Values and Current Analysis for NMP2

Input BWRVIP-138R1 Value Current Analysis for NMP2

JP Beam Material Alloy X-750 Modified Alloy X-718

Elastic Modulus @100°F 30.8E6 psi 28.8E6 psi

Elastic Modulus @550°F 28.9E6 psi 27.0E6 psi

Yield Strength @550°F 92.8 ksi 90.7 ksi

Ultimate Strength @550°F 160.0 ksi 160.0 ksi

Design Stress Intensity Sm @5500 F 53.3 ksi 50.8 ksi

Flow Stress @550°F 126.4 ksi 125.3 ksi

NWC IGSCC CGR (Eq.) da/dt=-5.9E-9K 25 in/hr Two assumptions are used:Upper Bound CGR lE-4in/hr Factor of 2 on BWRVIP NWC Line; no

Lower Bound CGR None lower bound plateauFactor of 10 on BWRVIP NWC Line; lowerbound plateau at 2.835E-7 in/hr.

HWC IGSCC CGR da/dt=-2.96E-9K 25 in/hr Same as NWC CGR

Upper Bound CGR 5E-5 in/hr

Lower Bound CGR None

99% Percentile Bolt Preload 24,592 lb 25,000 lb

Hydraulic Load 12,000 lb 12,000 lb


8-6

W-2-

SI O A i\OI L¸ Hod Down

Figure 1 Jet Pump Beam Inspection Regions

Figure 2 Modified Alloy 718 Jet Pump Beam

a,c


8-7

a,c

Figure 3 Fabrication Process of Modified AHoy 718 Jet Pump Beam


8-8

a,c

Figure 4 Yield and Tensile Strength of Modified Alloy 718 Compared to Alloy X-750


8-9

a,c

Figure 5 Elongation and Reduction of Area of Modified Alloy 718 Compared to Alloy X-750


8-10

LaO a "215.6 MPa

300*C

b

* In-reactor resultsby Causey et al,

0 10 I 2

dpaCalculated stress relaxation of Inconel X-750 at 300"C,

3x 10- dpa/s with experimental data of the similar condi-tion.

1.0

014 M8

-in-: mewed

.L4bzjns~

4Tz=300C

Ad(0,T 1O_j

S0.4I-

0. a I

) 0.2 0.4 U6do~es [c*,sJ

0.8 1.0

Stress relaxation for Inconel 718. The hollow circle,represents bend stress relaxation measured after in-pile irradi-ation at 315"C

Figure 6 Stress Relaxation of Alloy X-750 and Alloy 718 in an Irradiated Environment


8-11

10l

SInmos a (3020C (576 F))

0lllll0 Host A (RT)K3He1t A (RT)

"'N (2) MHiot B (3021C (576e F))

10 AHost C (RT)

10

I°=~~~ ~ I II+- JAI"•• "::: "- 1o 1-,.

10 10 10 5110 10 7 10 10

Fatigue Life N Number of cycles) RT: Roomi, TwImpertur

(1) Suair-controllod fatigue testing (Strain ratio: -1)

(2) Lomd-voontroIItd Wpmgu tasting (Stres ratio: -1)

Figure 7 Fatigue Test Results for Modifed Alloy 718 and Alloy X-750


8-12

a,c

" Temperature: 288*C• DO: 20ppm* Applied Strain: 1%' Test time: 500 h

Graht Wool

3tC

Li20

Figure 8 CBB (Creviced Bent Beam) Test Device and Results for Modified Alloy 718


8-13

a,c

Figure 9 Cross-section of Modified Alloy 718 Test specimen after the CBB test

"MW

IW'E

I

' Aley X-7"Oj,5 (HegRE2)

- e~w TyeM

Ssw~iuAS

bAley 71SI(HeatJl)

0 so 1w I

C- Gppb

Figure 10 CBB Test Results for Modified Alloy 718, Alloy X-750, and 304SS(2880 C Water - 8 ppm 02)


8-14

E

1.0

0.8

0.6

pe'g

Aloy X-750(1093oC/1 h ±704°C/20h)(Heat RE2)

S

Conventional Alloy 718(1010 °C/lh + (718 OCl8h-.6210CY18h)(Heat J2)

1.0

0.8

0.6

*O .Oao O

1.04 U -

I...

SO

0.8-Modified AIloy 718(1010°C/lh+704OC/6h)(Heat JA)

0.6 m

I I I a A i i a a I a a A I

500 1000GB.

Distance From Grain Boundary, nm

Figure 11 Chromium Profides at Grain Boundaries for Modified Alloy 718 and Alloy X-750


8-15

Alloy X-750(1 0930C/1 h +704°C/20h)

(Heat RE2)

Conventional Alloy 718(1010OC/lh +718°C/8h)

621 0C)/total 18h)

(Heat J2)

Modified Alloy 718(1010 0C/lh +704°C/6h)

(Heat J1)

0.2 jm

Figure 12 TEM Photos near the Grain Boundaries of Modified Alloy 718, Conventional Alloy718and Alloy X-750


8-16

II

1000

900

800

700

600

500

400

300

200

100

0

. U

ounve of alloy X- 750 E3]

26CM F)Pure later(DO•. ____

SAModfld A- oy71 (Host E) : NoFare

eAMlY X-750 (Heat REM: Feaur. E3]

0 2000 4000 eoooTest Time (hr)

8000 10000 12000

Figure 13 Constant Load Test Results for Modified Alloy 718 and Alloy X-750

a,c

Figure 14 Drop-off Time from Maximum Load to 1/2 Maximum Load of Modified Alloy 718 andAiloy-X-750 after Rising Load Test


8-17

a,c

Figure 15 SCC Growth Rates for Modified Alloy 718 and Alloy X-750 Compared to the BWRVIP-138R1 Relationship


8-18

r - - --------r - - - - - - - - -r -INPUT ANALYSIS OUTPUT

1. Limit Load Analysis forI Loads, Flow Stress, Allowable Flaw Sizes p Allowable Flaw SizesI Crack Planes

2. Linear Elastic Static FiniteMaterial Properties 0 Element Analysis for Stresses Stress ProfilesLoads, Beam Geometry

Stress IntensitySolutions -1 3. LEFM Analysis to determine

Stress Intensity Factors

Stress IntensityFactors

1I I

Initial Flaw SizeCrack Growth RateInitial Flaw SizeCrack Growth Rate

4. Crack Growth Analysis todetermine Inspection Intervals

Flaw Tolerance,RecommendedInspection Intervals

- -

Figure 16 Analysis Flowchart for the Toshiba Modified Alloy 718 Jet Pump Beam FractureMechanics Evaluation


8-19

ýJFixed Degree of freedom toprevent rigid body motion

Support

Figure 17 Analysis Model and Boundary Conditions


8-20

-17

I

- W - . -ý -- - -- ------- ------ W

Finbt LUflgt Surface Crack

Initl SSemi-elliptic crackInitial semi-circular - Semi-elliptic N extending to the -* Edge crack

Crack Crack entire width

Figure 18 Postulated Surface Crack


8-21

a,c

Figure 19. Crack Growth Rates Used in the Evaluation


8-22

31 (AV(TOP13lX -105855104 -- 15922SHX -42319

-9451-2979349299631643422905

___ 293773584642319

Figure 20 Maximum Principal Stresses in the Toshiba Modified Alloy 718 Beam


8-23

TOP

rum -losesW -54138

WM -38658-54138

i -43806-33473

m-23140S-12.807

-247478.59

2852538858

W 48

Sa -XP

I MODIFIED Alloy 718! !

I WVI-38R140

30

20

10

RW 3 1.0P W sO SMPmOuMLUA - f*GAWrfNsow0UwCML

0 as n am o Ri

'U

V2

3

-10

-20

Distance x from surface, in.

Figure 21 Comparison of Longitudinal Stresses from BWRVIP-138RI and Present Analysis for the Modified Alloy 718 Beam


8-24

1.00

0.10

0 25 305 10 is 20

Rosidual Life, years

GMOW 3 JOf PU , W^SWTMK BIC, amf PB9I1U.E

CBE CRAM APPOl ,C-d flFEjzJ V

ZK010.0.0

-1 r- T- 7 r- T II "-I- -L 1- A. 1 1 t J t J L I L j t j

f. -.11 - -+ - F- -1 A 4 i -i + f- i 1ý 4.,4- 1- 4- - 4 - -4 -4 - 4- - 1 - 4 4

j L 1,

r I :I 1 1:7 1 -,j r

ý4 4 -A- 4- -4 1- -4 ý4 L

4 4 -1- 4- -1 -4 k- -4

J 1, -1 -1 1 L J L L .1 1, A L -1 L J, j 1,

01 1

10 20 25 30

I Denm -LENM I

Figure 22 Residual Life Predictions for the Alloy 718 and the X-750 Beams Using the BWRVIP-138R1 NWC Line


8-25

1.00

0.10

0.010

_ _ _ I __..I __............. ................1................. ...........Residual Life as a function of crack depth

-Residul Life a function of crack halt-length

5 20 Z5 30

Residual Life, years45 5o35 4010 15

Figure 23 Residual Life Predictions for the Alloy 718 Beam Using Curve A (Factor of 2 lower thanthe BWRVIP-138R1 NWC Line)


8-26

*1

I

1

0.1

0.010

-Residual Ufe as a tumtion of Crack Depth

-- esidual Ufe " a function of credi half-tlerth

40 12020 60

Residual Ufe, years

30 100

Figure 24 Residual Life Predictions for the Alloy 718 Beam Using Curve B (Factor of 10 Lowerthan the BWRVIP-138R1 NWC Line)


ATTACHMENT 3

AFFIDAVIT FROM WESTINGHOUSE ELECTRIC COMPANY LLC

JUSTIFYING WITHHOLDING PROPRIETARY INFORMATION

Nine Mile Point Nuclear Station, LLCMarch 11, 2013

CAW-13-3632

AFFIDAVIT

COMMONWEALTH OF PENNSYLVANIA:

SS

COUNTY OF BUTLER:

Before me, the undersigned authority, personally appeared James A. Gresham, who, being by me

duly sworn according to law, deposes and says that he is authorized to execute this Affidavit on behalf of

Westinghouse Electric Company LLC (Westinghouse), and that the averments of fact set forth in this

Affidavit are true and correct to the best of his knowledge, information, and belief:

I James A. Gresham, Manager

Regulatory Compliance

Sworn to and subscribed before me

this 28th day of February 2013

Notary Public[I /,

--C MONWEALTH OF PENNSYLVANIA

INotarial Seal

Anne M. Stegman, Notary PublicUnity Twp., Westmoreland County

My Commisslon Expires Aug. 7, 2016I

MEMBEP, PENNSYLVANIA ASSOCIATION OF NOTARIES

2 CAW-13-3632

(1) 1 am Manager, Regulatory Compliance, in Nuclear Services, Westinghouse Electric

Company LLC (Westinghouse), and as such, I have been specifically delegated the function of

reviewing the proprietary information sought to be withheld from public disclosure in connection

with nuclear power plant licensing and rule making proceedings, and am authorized to apply for

its withholding on behalf of Westinghouse.

(2) I am making this Affidavit in conformance with the provisions of 10 CFR Section 2.390 of the

Commission's regulations and in conjunction with the Westinghouse Application for Withholding

Proprietary Information from Public Disclosure accompanying this Affidavit.

(3) 1 have personal knowledge of the criteria and procedures utilized by Westinghouse in designating

information as a trade secret, privileged or as confidential commercial or financial information.

(4) Pursuant to the provisions of paragraph (b)(4) of Section 2.390 of the Commission's regulations,

the following is furnished for consideration by the Commission in determining whether the

information sought to be withheld from public disclosure should be withheld.

(i) The information sought to be withheld from public disclosure is owned and has been held

in confidence by Westinghouse.

(ii) The information is of a type customarily held in confidence by Westinghouse and not

customarily disclosed to the public. Westinghouse has a rational basis for determining

the types of information customarily held in confidence by it and, in that connection,

utilizes a system to determine when and whether to hold certain types of information in

confidence. The application of that system and the substance of that system constitutes

Westinghouse policy and provides the rational basis required.

Under that system, information is held in confidence if it falls in one or more of several

types, the release of which might result in the loss of an existing or potential competitive

advantage, as follows:

(a) The information reveals the distinguishing aspects of a process (or component,

structure, tool, method, etc.) where prevention of its use by any of

3 CAW- 13-3632

Westinghouse's competitors without license from Westinghouse constitutes a

competitive economic advantage over other companies.

(b) It consists of supporting data, including test data, relative to a process (or

component, structure, tool, method, etc.), the application of which data secures a

competitive economic advantage, e.g., by optimization or improved

marketability.

(c) Its use by a competitor would reduce his expenditure of resources or improve his

competitive position in the design, manufacture, shipment, installation, assurance

of quality, or licensing a similar product.

(d) It reveals cost or price information, production capacities, budget levels, or

commercial strategies of Westinghouse, its customers or suppliers.

(e) It reveals aspects of past, present, or future Westinghouse or customer funded

development plans and programs of potential commercial value to Westinghouse.

(f) It contains patentable ideas, for which patent protection may be desirable.

There are sound policy reasons behind the Westinghouse system which include the

following:

(a) The use of such information by Westinghouse gives Westinghouse a competitive

advantage over its competitors. It is, therefore, withheld from disclosure to

protect the Westinghouse competitive position.

(b) It is information that is marketable in many ways. The extent to which such

information is available to competitors diminishes the Westinghouse ability to

sell products and services involving the use of the information.

(c) Use by our competitor would put Westinghouse at a competitive disadvantage by

reducing his expenditure of resources at our expense.

4 CAW-13-3632

(d) Each component of proprietary information pertinent to a particular competitive

advantage is potentially as valuable as the total competitive advantage. If

competitors acquire components of proprietary information, any one component

may be the key to the entire puzzle, thereby depriving Westinghouse of a

competitive advantage.

(e) Unrestricted disclosure would jeopardize the position of prominence of

Westinghouse in the world market, and thereby give a market advantage to the

competition of those countries.

(f) The Westinghouse capacity to invest corporate assets in research and

development depends upon the success in obtaining and maintaining a

competitive advantage,

(iii) The information is being transmitted to the Commission in confidence and, under the

provisions of 10 CFR Section 2.390, it is to be received in confidence by the

Commission.

(iv) The information sought to be protected is not available in public sources or available

information has not been previously employed in the same original manner or method to

the best of our knowledge and belief.

(v) The proprietary information sought to be withheld in this submittal is that which is

appropriately marked in XGEN-2012-25, Revision 1, "Technical Basis for the Inspection

Frequency of the Modified Alloy 718 Jet Pump Beam" (Proprietary), dated January 2013,

for submittal to the Commission, being transmitted by Constellation Energy letter and

Application for Withholding Proprietary Information from Public Disclosure, to the

Document Control Desk. The proprietary information as submitted by Westinghouse is

that associated with Constellation Energy's submittal regarding jet pump beam inspection

frequency, and may be used only for that purpose.

5 CAW- 13-3632

This information is part of that which will enable Westinghouse to:

(a) Sell the use of the information to its customers for the purpose of supplying

Alloy 718 as reactor components.

Further this information has substantial commercial value as follows:

(a) The information requested to be withheld reveals the distinguishing aspects of a

methodology which was developed by Westinghouse.

Public disclosure of this proprietary information is likely to cause substantial harm to the

competitive position of Westinghouse because it would enhance the ability of

competitors to provide similar Alloy 718 material and licensing defense services for

commercial power reactors without commensurate expenses. Also, public disclosure of

the information would enable others to use the information to meet NRC requirements for

licensing documentation without purchasing the right to use the information.

The development of the technology described in part by the information is the result of

applying the results of many years of experience in an intensive Westinghouse effort and

the expenditure of a considerable sum of money.

In order for competitors of Westinghouse to duplicate this information, similar technical

programs would have to be performed and a significant manpower effort, having the

requisite talent and experience, would have to be expended.

Further the deponent sayeth not.

Documents

XGEN-2012-25-NP, Revision 1, 'Westinghouse Engineering ... · XGEN-2012-25-NP February 2013 Revision I. 3-1 3 JET PUMP DESIGN, MATERIAL AND OPERATION Jet pump beams are located at