ML14216A406

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Attachment 5, WCAP-17444-NP, Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Seabrook Unit 1, (Non-proprietary)
ML14216A406
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Issue date: 07/24/2014
From: Freed A, Udyawar A
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SBK-L-14-102 WCAP-17444-NP, Rev. 0
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Attachment 5 WCAP-17444-NP Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Seabrook Unit 1 (Non-proprietary)

Westinghouse Non-Proprietary Class 3 WCAP-17444-NP October 2011 Revision 0 Reactor Vessel Closure HeadNessel Flange Requirements Evaluation for Seabrook Unit 1 Westinghouse

WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-17444-NP Revision 0 Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Seabrook Unit 1 Amy E. Freed*

Aging Management & License Renewal Services Anees Udyawar*

Piping Analysis & Fracture Mechanics October 2011 Reviewer: Nathan L. Glunt*

Piping Analysis & Fracture Mechanics Approved: Michael G. Semmler*, Acting Manager Aging Management & License Renewal Services

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

Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066, USA

© 2011 Westinghouse Electric Company LLC All Rights Reserved

WESTINGHOUSE NON-PROPRIETARY CLASS 3 ii TABLE OF CONTENTS LIS T OF TA B L ES ...................................................................................................................................... iii LIS T OF F IG U RE S ..................................................................................................................................... iv EX EC U TIVE SU MM A RY ........................................................................................................................... v 1 INTRODUCTION ........................................................................................................ 1I-1I 2 ILLUSTRATION OF SAFETY IMPLICATIONS OF FLANGE REQUIREMENT............. 2-1 3 TECH N IC A L A PPRO A C H .......................................................................................................... 3-1 4 GEOMETRY, STRESSES, AND MATERIAL PROPERTIES ................................................. 4-1 5 FRACTURE ANALYSIS METHODS ......................................................................................... 5-1 5.1 STRESS INTENSITY FACTOR CALCULATIONS ................................................. 5-1 5.2 FRACTURE TOUGHNESS ............................................................................................ 5-2 6 FLAN G E IN TE G R ITY ................................................................................................................ 6-1 7 ALTERNATIVE BOLTUP REQUIREMENTS ........................................................................ 7-1 8 RE FEREN C ES ............................................................................................................................. 8-1 APPENDIX A REACTOR PRESSURE VESSEL INSPECTION RELIABILITY .................... A-1 APPENDIX B THERMAL AGING OF FERRITIC RPV STEELS AT REACTOR OPERATING TEMPERATURES ........................................................................ B-1 APPENDIX C STRESS DISTRIBUTIONS IN THE CLOSURE HEAD REGION ................... C-I WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 I11 LIST OF TABLES Table 4-1 Dimensions for the Seabrook Unit 1 Closure Head Region ........................................ 4-2 Table 4-2 RTNDT Values for the Seabrook Unit I Closure Head Region .......................................... 4-3 Table 6-1 Axial Stress Distributions at the Closure Flange Region - Seabrook Unit I ................... 6-2 Table 6-2 Limiting Stress Intensity Factors at One-Tenth of the Wall Thickness and Fracture Toughness Values for Seabrook Unit 1 Boltup and Heatup/Cooldown Transient C on d itio n s ........................................................................................................................ 6 -3 Table 7-1 Limiting T-RTNDT Value at Boltup Conditions for Seabrook Unit 1 ................................ 7-2 Table 7-2 Comparison of Various Plant Designs Boltup Requirements .......................................... 7-2 Table A- I N um ber of M easurem ents ............................................................................................... A -4 Table B- I Compositions of the Materials Studied by DeVan et al .................................................. B-2 Table B-2 T41J Before and After Long-Term Thermal Aging .......................................................... B-2 Table B-3 Composition of A533B-1 Materials Studied by Williams and Ellis ............................... B-4 Table C- I Stress for Upper Head to Flange Transient Region (Cut 2) ............................................ C-4 Table C-2 Stress for Upper Head to Flange Transient Region (Cut 3) ............................................ C-7 WCAP-1 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 iv LIST OF FIGURES Figure 1-1 Illustration of the Impact of the Flange Requirement for a Typical PWR Plant .............. 1-2 Figure 2-1 Illustration of the Flange Requirement and its Effect on the Operating Window for a Typical PWR Steady-State P-T Limit Curve with a LTOPS Single Setpoint .......... 2-2 Figure 2-2 Illustration of the Flange Requirement and its Effect on the Operating Window for a Typical PWR Steady-State P-T Limit Curve with LTOPS Variable Setpoints ........ 2-3 Figure 4-1 Geometry of the Upper Head/Flange Region of the Seabrook Unit I Reactor Vessel ............................................................................................................................... 4 -2 Figure 6-1 Crack Driving Force as a Function of Flaw Size: Outside Surface Circumferential Flaw in the Torus to Flange Region Weld (Cut 3) for Seabrook U n it 1 ............................................................................................................................... 6 -4 Figure 6-2 Crack Driving Force as a Function of Flaw Size: Outside Surface Circumferential Flaw in the Dome to Torus Region Weld (Cut 2) for Seabrook Unit I ........................... 6-5 Figure 7-1 Limiting Stress Intensity Factor Value at Boltup Conditions for Seabrook Unit I .......... 7-1 Figure A-I Probability of Detection Performance for Passed and Passed Plus Failed Candidates for Appendix VIII Supplement 4, from the Outside Surface as a function of the flaw through wall extent (TWE). Both automated and manual techniques are included ................................................................................................... A -3 Figure A-2 POD for Inside Surface Examinations, Pass and Pass + Failed Candidates, Passed and Pass Plus Failed Candidates are included ................................................................ A-4 Figure A-3 Probability of Detection for Automated RPV Examinations Considering Both Inside and Outside Access. Passed and Passed Plus Failed Candidates are shown ....... A-5 Figure A-4 POD for Pass and Failed Candidates, Considering ID and OD Automated Demonstrations and Manual OD Demonstrations .......................................................... A-6 Figure A-5 Histogram of Depth Successful Sizing Candidate Test Scores, Appendix VIII, Supplement 4. Examinations Were Performed Both From the Inside and Outside S u rfaces ............................................................................................................ .............. A -7 Figure A -6 Sizing Error Surface M odel ........................................................................................... A -8 Figure A-7 Plan View of Sizing Error Surface M odel ...................................................................... A-9 Figure A-8 Probability of Correct Sizing for Passed Candidates, Appendix VIII Supplement 4 Reporting Threshold A' = 0.15 inch ..................................... A-11 Figure A-9 Probability of Correct Rejection/Reporting (PCR) for automated techniques, Considering Passed and Passed plus Failed Candidates, includes both inside and outside surface information. Reporting Criterion A' = 0.15 inch ................................. A-12 Figure B- I Plot of Vickers Hardness Versus Time for Thermal Aging at 330'C ......................... B-5 Figure C - 1 C losure H ead R egion ...................................................................................................... C -2 Figure C-2 Generic Stress Component Orientation .......................................................................... C-3 WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 V EXECUTIVE

SUMMARY

This report provides the methodology and results to support the elimination of the minimum temperature flange requirement. from the Seabrook Unit I normal operation heatup and cooldown pressure-temperature (P-T) limit curves, based on 10 CFR 50 Appendix G.

The minimum temperature flange requirement was originally based on concerns about the fracture margin in the reactor vessel closure head/vessel flange region. During the boltup process, outside surface stresses in this region typically reach over 70 percent of the steady state stress, without being at steady state temperature. The margin of 120'F and the pressure limitation of 20 percent of hydrostatic test pressure were developed using the Kla material fracture toughness to ensure that appropriate margins would be maintained. However, the flange requirement based on Kia can cause severe operational limitations when instrument uncertainties are included for the Low Temperature Overpressure Protection (LTOP) system in Pressurized Water Reactors (PWRs). Therefore, improved knowledge of fracture toughness and other issues which affect the integrity of the reactor vessel have led to the use of K1. material fracture toughness in the development of pressure-temperature curves, as specified in ASME Code Section XI, Appendix G.

The goal of the evaluation provided herein is to demonstrate the structural integrity of the Seabrook Unit I closure head during the boltup, plant heatup and plant cooldown processes, and further show that the minimum temperature flange requirement can be reduced or eliminated from the P-T limit curves with use of the higher Ki, fracture toughness.

In order to show that the structural integrity of the closure head and vessel flange region is maintained, a fracture mechanics evaluation was performed in this report. Axial and circumferential flaws with aspect ratios of 6:1 and flaw depths of ten percent of the wall thickness were postulated in the limiting closure head flange region for Seabrook. The crack driving force, stress intensity factors, for these postulated flaws were calculated for the limiting boltup and heatup/cooldown transient conditions based on the plant specific geometry, applied stresses, and the postulated flaw parameters. The calculated stress intensity factors were shown to be less than the calculated material fracture toughness values for the associated conditions for Seabrook. Therefore, it was concluded that the structural integrity of the closure head and vessel flange region is maintained for Seabrook at the boltup and heatup/cooldown conditions.

In order to completely eliminate the minimum temperature flange requirement from the Seabrook P-T limit curves, the limiting temperature for the flange requirements should be less than the minimum boltup temperature required for the Seabrook P-T limit curves. Based on the evaluation performed in this report, the alternative limiting temperature for flange requirements in the Seabrook P-T limit curves can be as low as 46°F, based on the limiting initial RTNDT value of 30'F for the closure head/vessel flange region.

Since the calculated value of 46°F is less than the minimum boltup temperature of 60'F for Seabrook Unit 1, no additional boltup temperature requirements are necessary, and the minimum temperature requirement for the flange can be completely eliminated from the Seabrook P-T limit curves.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-1 INTRODUCTION 10 CFR Part 50, Appendix G [Reference 1] contains requirements for pressure-temperature limits for the primary system, and requirements for the metal temperature of the closure head flange and vessel flange regions. The pressure-temperature (P-T) limits are to be determined using the methodology of ASME Section XI, Appendix G [Reference 2], with the flange temperature requirements specified in 10 CFR Part 50 Appendix G. The flange temperature requirement states that the metal temperature at the closure flange regions must exceed the material unirradiated RTNDT by at least 120'F for normal operation when the pressure exceeds 20 percent of the pre-service hydrostatic test pressure, which is 621 psig for a typical PWR.

This requirement was originally based on concerns about the fracture margin in the closure head/vessel flange region. During the boltup process, outside surface stresses in this region typically reach over 70 percent of the steady state stress, without being at steady state temperature. The margin of 120'F and the pressure limitation of 20 percent of hydrostatic test pressure were developed using the Kla fracture toughness to ensure that appropriate margins would be maintained for the structural integrity of the closure head flange region. Improved knowledge of fracture toughness and other issues which affect the integrity of the reactor vessel have led to the use of Ki, in the development of pressure-temperature curves, as contained in ASME Code Section XI, Appendix G.

Figure 1-1 illustrates the problem created by the flange requirements for a typical PWR heatup curve. It is easy to see that the heatup curve using Klc provides for a much higher allowable pressure through the entire range of temperatures. For this plant, however, the benefit is negated at temperatures below RTNDT+120°F because of the flange requirement of 10 CFR Part 50, Appendix G. The flange requirement of 10 CFR Part 50 was originally developed using the Kia fracture toughness. The goal of the evaluation provided herein is to demonstrate the structural integrity of the Seabrook Unit 1 closure head during the boltup, plant heatup and plant cooldown processes. The first question to be addressed is: With the higher K1 , fracture toughness now known to be applicable, is there still a concern about the structural integrity of the closure head during boltup? The second question is: Can the minimum temperature requirement for the flange then be reduced or completely eliminated from the Seabrook P-T limit curves?

Note that there are several locations in this report where proprietary information has been identified and bracketed. For each of the bracketed locations, reasons for proprietary classifications are given using a standardized system. The proprietary brackets are labeled with three different letters to provide this information. The explanation for each letter is given below:

a. The information reveals the distinguishing aspects of a process or component, structure,tool, method, etc., and the prevention of its use by Westinghouse's competitors, withoutlicense from Westinghouse, gives Westinghouse a competitive economic advantage.
c. The information, if used by a competitor, would reduce the competitor's expenditure of resources or improve the competitor's advantage in the design, manufacture, shipment, installation, assurance of quality, or licensing of a similar product.
e. The information reveals aspects of past, present, or future Westinghouse or customer funded development plans and programs of potential commercial value to Westinghouse.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-2 WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-2 2500 2250 2000 1750 1500 CL 1250 I-1000 750 i1@~~---

5001 250 i RTNDT + 120°F 0iI 0 50 100 150 200 250 300 350 Temperature (°F)

Figure 1-1 Illustration of the Impact of the Flange Requirement for a Typical PWR Plant WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-1 2 ILLUSTRATION OF SAFETY IMPLICATIONS OF FLANGE REQUIREMENT There are important safety implications which are associated with the flange requirement, as illustrated by Figures 2-1 and 2-2. The safety concern is the narrow operating window at low temperatures imposed by the flange requirement. The flange requirement sets a pressure limit of 621 psi for a PWR (20 percent of hydrostatic test pressure). Thus, no matter how good the toughness of the vessel, the P-T limit curve may be superseded by the flange requirement for temperatures below RTNDT + 120'F. This requirement was originally imposed to ensure the integrity of the flange region during boltup.

The flange requirement can cause severe operational limitations when instrument uncertainties are added to the lower temperature range limit (621 psi) for the Low Temperature Overpressure Protection (LTOP) system of PWRs. The minimum pressure required to cool the seals of the main coolant pumps is 325 psi, so the operating window sometimes becomes very small. If the operator allows the pressure to drop below the pump seal limit, the seals could fail, causing the equivalent of a small break Loss of Coolant Accident (LOCA), a significant safety problem.

Elimination of the flange requirement will significantly widen the operating window for most PWRs.

An example is provided to illustrate this situation for a typical operating.PWR plant. The flange requirements for this example vessel are shown in the P-T limit curves in Figures 2-1 and 2-2.

Figures 2-1 and 2-2 include the P-T limit curve along with typical LTOPS single and variable setpoint curves, respectively.

The simpler case is the one shown in Figure 2-1. Due to instrument uncertainties, the operating window, shown in Figure 2-1, between the LTOPS single setpoint and the pump seal limit is relatively small when the flange requirements are incorporated in the P-T limit curve.

Elimination of the flange requirement for the example plant with the LTOPS single setpoint curve would result in an approximate increase of 100 psi to the LTOPS curve. As a result, the operating window also increases 100 psi. Similarly, Figure 2-2 illustrates the same concept using a LTOPS variable setpoint curve, which is the type of curve Seabrook Unit I utilizes. As seen in Figure 2-2, elimination of the flange requirement for this scenario provides an even greater improvement to the operating window. This change will make a significant improvement in plant safety by reducing the probability of a small LOCA, and easing the burden on the operators.

This is only one example of the impact of the flange requirement. Every operating PWR plant will have a different situation, but the operational safety level will certainly be generally improved by the elimination of this requirement.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-2 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-2 2500 2250 2000 1750 1500 0.

1250 a, P-T Limit Curve a- without flange 1000 requirements -

N - P-T Umit Curve S"with flange LTOP single setpointcurve 750 requirements withoutflange requirements

/

500

-" ------- I-- ._ ---

Additional Oprtn Margn (ihutfag rqiements)

Operating W indow (with flange requirements) - - - -

250 Pump Seal LTOP single setpoint curve Limit 325 psi with flange requirements 0

2 0 50 100 RTNDT+1 0oF 150 200 250 300 Temperature (°F)

Figure 2-1 Illustration of the Flange Requirement and its Effect on the Operating Window for a Typical PWR Steady-State P-T Limit Curve with a LTOPS Single Setpoint WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-3 2-3 WESTINGHOUSE NON-PROPRIETARY CLASS 3 2500 2250 2000 1750 1500

__ P-T Limit Curve L 1250 without flange V1 requirements 1000 - P-T Limit Curve LTOP variable setpoint curve

- with flange without flange re uirements 750 ___.______ _____requirements

.. .. .. .. -- (w/o*flng reurmnsprating Window 500itional , (with flange requirements) 250 PumpSeal LTOP variable setpoint curve Limit 325 psi with flange requirements 0 I 0 50 100 RTNDT+ 120OF 150 200 250 300 Temperature (*F)

Figure 2-2 Illustration of the Flange Requirement and its Effect on the Operating Window for a Typical PWR Steady-State P-T Limit Curve with LTOPS Variable Setpoints WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-1 3 TECHNICAL APPROACH It is stated in 10 CFR Part 50, Appendix G [Reference 1] that "[t]he minimum temperature requirements ... pertain to the controlling material, which is either the material in the closure flange or the material in the beltline region with the highest reference temperature...the minimum temperature requirements and the controlling material depend on the operating condition (i.e.,

hydrostatic pressure and leak tests, or normal operation including anticipated normal operational occurrences), the vessel pressure, whether fuel is in the vessel, and whether the core is critical.

The metal temperature of the controlling material, in the region of the controlling material which has the least favorable combination of stress and temperature, must exceed the appropriate minimum temperature requirement for the condition and pressure of the vessel specified in Table 1 [of 10 CFR Part 50, Appendix G]." Footnote 2 to Table I in 10 CFR Part 50, Appendix G specifies that RPV minimum temperature requirements related to RPV closure flange considerations shall be based on "[t]he highest reference temperature of the material in the closure flange region that is highly stressed by bolt preload."

Along with the above criteria from 10 CFR Part 50 Appendix G, the rule further states that the metal temperature at the closure flange regions must exceed the material unirradiated RTNDT by at least 120'F for normal operation when the pressure exceeds 20 percent of the pre-service hydrostatic test pressure, which is 621 psig for a typical PWR. As discussed in Section 2.0, this flange requirement can cause severe operational limitations when instrument uncertainties are added to the lower temperature range limit (621 psi) for the LTOP system of PWRs. Therefore, the objective of the analysis performed herein for Seabrook Unit I will be to demonstrate that the conservative minimum temperature requirements related to 10 CFR Part 50, Appendix G for the closure head flange are not necessary and can be eliminated from the P-T limit curves.

Additionally, another goal of this evaluation is to demonstrate that the structural integrity of the reactor vessel closure head is maintained during both the boltup and normal operating conditions.

The fracture mechanics analysis performed in this report analyzed two postulated flaw configurations: an axial and a circumferential flaw which are normal (perpendicular) to their corresponding stress components in the Seabrook Unit 1 closure head flange regions under boltup, 100 0F/hr heatup, 100 0 F/hr cooldown, and steady-state conditions. Finite element analyses were performed for the transient loadings and closure head geometry specific to Seabrook (as detailed in Section 4.0 and Appendix C); the stresses calculated at the critical locations within the flange region were used to develop the stress intensity factors (K1 ), the driving force on a crack.

The stress intensity factors were determined for postulated semi-elliptical, outside diameter surface breaking flaws with an aspect ratio (flaw length/flaw depth) of 6:1; further discussion on the calculation of the stress intensity factors is available in Section 5.0.

The stress intensity factors for flaws with a depth of 10% of the wall thickness (0. 1T) were then compared to the lower bound static crack initiation fracture toughness (K1 ,) values (see Section 5.3) determined from the nil-ductility transition reference temperature (RTNDT) for the closure head/vessel flange region materials. The use of 0.IT reference flaw size for the stress intensity factor analysis is based on industry inspection detection capability as discussed in Appendix A for flaws in the reactor pressure vessels.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-2 The limiting nil-ductility transition reference temperature in the closure head flange region is provided in Section 4.0. An assessment of potential changes in the material RTNDT values for the closure flange materials (carbon steel and low-alloy steel) due to thermal aging resulting from exposure to the high PWR operating temperature environment are detailed in Appendix B. Based on the conclusions from Appendix B and EPRI MRP-80 [Reference 3], it was determined that there will be no significant impact on the RTNDT due to thermal aging for the carbon steels and low alloy steels used in the closure head flange region.

The technical analysis detailed in Section 5.0 will demonstrate the structural integrity of the closure head flange region by comparing the material fracture toughness (K1I) of the closure head/vessel flange region to the stress intensity factors (K1 ) for a postulated 0.1 T surface flaw in the closure head during boltup, heatup, cooldown and steady-state conditions.

A separate evaluation is performed in Section 6.0 to determine the alternative boltup temperature requirement based on the limiting stress intensity factor for boltup conditions at a depth of ten-percent of the wall thickness. Current requirements in 10 CFR 50, Appendix G state that the metal temperature at the closure head/vessel flange regions must exceed the material unirradiated RTNDT (RTNDT(u)) by at least 120-F for the operating conditions when the pressure exceeds 20 percent of the pre-service hydrostatic test pressure, which is typically 621 psig for a PWR.

T > 120OF + RTNDT(U)

The alternative boltup temperature requirement (T - RTND-(U)) is the temperature at which the calculated K1c curve intersects the limiting boltup stress intensity factor. This temperature (T -

RTNDT(U)) is used to determine whether the minimum flange temperature can be lowered; therefore, reducing the flange requirement portion of the heatup/cooldown P-T limit curves. In some instances, the calculated alternative flange temperature may be below the minimum boltup temperature; therefore, justifying elimination of flange requirement from the P-T limit curves.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-1 4 GEOMETRY, STRESSES, AND MATERIAL PROPERTIES Finite element stress analyses have been performed on the closure head geometry and transient loading specific to Seabrook Unit 1, and the results are tabulated and discussed in Appendix C of this report. The geometry of the closure head region for Seabrook Unit I is shown in Figure 4-1.

Table 4-1 presents the closure head thickness along with the inner radius dimensions that correspond to the critical locations of interest (Cuts 2 and 3 in Figure 4-1) for the fracture mechanics analysis for Seabrook.

Stress analyses have been performed for the heatup/cooldown transients and boltup conditions in the closure head and vessel flange region for the two critical locations of interest (Figure 4-1).

The stress analysis was carried out with both temperature and pressure varying with time for the heatup and cooldown transients with a rate of 100°F per hour. The results for each time step are provided in Appendix C for Cuts 2 and 3, showing both hoop and axial (meridional) stresses.

These stress results were used to perform the fracture mechanics evaluations contained in this report for Seabrook Unit 1. The high stress locations in the closure head and vessel flange region are in the head, just above the bolting flange, corresponding with the location of two welds as shown in Figure 4-1. Although these reactor vessel welds have been stress relieved, a through-wall welding residual stress profile from ORNL/NRC/LTR-05/18 [Reference 6] was added to the boltup stresses as well as to the heatup/cooldown transient pressure and thermal stresses.

Furthermore, the highest stressed location in the closure head/vessel flange region is near the outside surface; therefore, the fracture evaluations postulate a flaw on the outside surface. The limiting stresses for the flange integrity fracture mechanics evaluation are presented in Section 6.0 for the analyzed boltup and heatup/cooldown conditions.

The fracture toughness properties for the materials in the Seabrook Unit I closure head/vessel flange region are summarized in Table 4-2. The unirradiated RTNDT is a material parameter determined from Charpy V-notch and drop-weight tests. It is designated as the higher of either the drop weight nil-ductility transition temperature (NDTT) or the temperature at which the material exhibits at least 50 ft-lbs of impact energy and 35 mil lateral expansion (normal to the major working direction) minus 60'F.

Neutron irradiation has been shown to produce embrittlement which reduces the toughness properties of reactor vessel steels; furthermore, the decrease in the toughness properties can be assessed by determining the shift to higher temperatures of the reference nil-ductility transition temperature, RTNDT, due to irradiation. Since the location of the closure flange region is far enough from the core such that the irradiation levels are very low, the shift in RTNDT is not measurably affected. The highest RTNDT for the closure head flange region of the Seabrook Unit I reactor vessel is 30'F, as shown in Table 4-2. This unirradiated RTNDT value is used in determining the fracture toughness values based on the methodology presented in Section 5 of this report.

WCAP- I7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-2 TOP HEAD DOME TO TORUS WELD S(CUT 2)

TORUS TO FLANGE K, WELD (CUT 3)

'Wý VESSEL FLANGE TO UPPER SHELL WELD Figure 4-1 Geometry of the Upper Head/Flange Region of the Seabrook Unit 1 Reactor Vessel Table 4-1 Dimensions for the Seabrook Unit 1 Closure Head Region (inches)

Location Inner Radius(s) Thickness(b)

Cut 2 86.00 7.190 Cut 3 86.00 8.833 Notes for Table 4- 1:

(a) Closure Head Inner Radius to the clad/base metal interface.

(b) Head thickness without cladding.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-3 Table 4-2 RTNDT Values for the Seabrook Unit 1 Closure Head Region a,c,e i

i WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 5-1 5 FRACTURE ANALYSIS METHODS The fracture evaluation was carried out using the approach suggested by Section XI Appendix G

[Reference 2]. A semi-elliptic surface flaw was postulated to exist in the highest stressed region, which is at the outside surface of the closure flange. The flaw depth of 10% of the wall thickness was postulated with an aspect ratio set at a flaw length six times the flaw depth.

5.1 STRESS INTENSITY FACTOR CALCULATIONS One of the key elements of a fracture evaluation is the determination of the driving force or stress intensity factor (KI). In most cases, the stress intensity factor for the structural integrity calculations utilized a representation of the actual stress profile rather than a linearization. The stress profile was represented by a 4th order polynomial:

t-): =CO+"-(51 ( t)'+-C52 ( t)2+"t-G -)3 + (4 (t where:

x = the through wall distance from the surface, inches t = the wall thickness, inches G stress perpendicular to the plane of the crack, ksi Gi coefficients of the stress profile curve fit (i = 0, 1, 2, 3, 4)

Since the closure head is a spherical dome, the stress intensity factors were calculated for an outside surface flaw modeled in a plate and cylinder. Based on the results of the comparison study, it was determined that the stress intensity factor solutions from the plate and cylinder models are very similar since the thickness to radius ratio is very small. As a result, for a surface flaw with length six times its depth, the stress intensity factor expression from API-579

[Reference 4] for a flaw modeled in a cylinder was used for the fracture mechanics evaluation for Seabrook.

The stress intensity factor, K1, can be calculated anywhere along the crack front. The point of maximum crack depth into the wall thickness is represented by qp = 90, and this location was found to also be the point of maximum Kj for the postulated cracks analyzed for Seabrook with an aspect ratio of 6:1. The following expression is used for calculating K, as a function of the angular location around the crack front (p). The units of K, are ksiii-n.

4 K, - -oG 1 (a/c,a/t,t/R,op)aj(-)

j=0 WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 5-2 The boundary correction factors Go, G1, G 2, G 3, and G4 are obtained by the procedure outlined in

[Reference 4]. The dimension "a" is the crack depth, "c" is the crack half length, "t" is the wall thickness, "R" is the inside radius, and "Q" is the flaw shape factor, which can be approximated by Q = I + 1.464 (a/c)165.

5.2 FRACTURE TOUGHNESS The calculated stress intensity factors (KI) for the postulated flaws in the closure head during boltup, heatup, and cooldown processes will then be compared to the flange region material fracture toughness (K,,) in order to determine the integrity of the closure head/vessel flange region.

The fracture toughness has been taken directly from the reference curves of Section XI, Appendix A [Reference 2]. In the transition temperature region, these curves can be represented by the following equations:

KIc = 33.2 + 20.734 exp [0.02 (T - RTNDT)]

where KI, is in units of ksifii/, T and RTNDT are in 'F.

The upper shelf temperature regime requires utilization of a shelf toughness which is not specified in the ASME Code. A value of 200 ksix/*i has been used here. This value is consistent with general practice in such evaluations, as shown for example in EPRI-NP-719-SR [Reference 5], which provided the background and technical basis for the development of Appendix A of Section XI.

The final key element in the determination of the fracture toughness is the value of RTNDT. The values of RTNDT for the Seabrook Unit I closure head/vessel flange region are shown in Table 4-

2. Based on Table 4-2, the highest initial RTNDT value of 30'F corresponds to the vessel flange, and will be used in the analyses contained in Sections 6 and 7 of this report.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-1 6 FLANGE INTEGRITY The goal of the evaluation is to demonstrate the structural integrity of the closure head during the boltup, plant heatup and plant cooldown processes. The first step in the evaluation of the closure head/flange region is to examine the stresses. The stresses which are affected by the boltup event are the axial, or meridional stresses, which are perpendicular to the nominal plane of the closure head to flange weld (see Figure C-2 in Appendix C). The hoop stresses for the boltup condition, as well as the heatup/cooldown transients are not as limiting as the axial stresses; therefore, particular attention is given to axial stresses and the corresponding circumferential flaw evaluation.

The boltup condition is the key condition to review here, in comparison with the heatup and cooldown operation, since the flange requirement applies to boltup conditions. No other transients result in stresses in this region at low temperatures. One might suggest that the cooldown transient would be limiting, but the boltup is governing for a number of reasons:

1. The cooldown transient has much higher temperatures in the head region than boltup.
2. Boltup stresses are tensile on the outside surface, whereas cooldown thermal stresses are tensile on the inside surface and compressive on the outside surface. The thermal stresses caused by the cooldown transient tend to counteract the boltup stresses.

Table 6-1 provides a comparison of the axial stresses at boltup with those at the governing heatup/cooldown transient time step, which occurs at the end of heatup (time step = 344.2 minutes). Note that the stresses at boltup are mostly bending, with a very small membrane stress; however, as the vessel is pressurized, the membrane stresses increase. The stress results were taken from a finite element analysis of the heatup/cooldown process. A through-wall welding residual stress profile from ORNL/NRC/LTR-05/18 [Reference 6] was added to the boltup stresses as well as to the heatup/cooldown transient pressure and thermal stresses.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-2 WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-2 ac,e Table 6-1 Axial Stress Distributions at the Closure Flange Region - Seabrook Unit I (ksi)

The relative impact of these stresses can best be addressed through a fracture evaluation. A semi-elliptic surface flaw was postulated at the outer surface of the closure head flange (flaw depth of 10 percent of the wall thickness from the outside surface), and the stress intensity factor, KI, was calculated for this postulated flaw. It was determined that an outside surface flaw would result in a more limiting stress intensity factor than the inside surface flaw. The limiting stress intensity factor results for the boltup condition are at the Cut 3 weld region (Figure 6-1), while the limiting stress intensity factor results are at Cut 2 for heatup at time step = 344.2 minutes (Figure 6-2).

The limiting stress intensity factor values for the boltup and heatup conditions are given in Table 6-2 at a flaw depth of 10% of the wall thickness from the outside surface. A safety factor of 2 is applied to the stress intensity factor in accordance with the ASME Section XI, Appendix G requirements.

It will be useful to highlight the difference in the integrity for the head region using the two values of fracture toughness at the boltup and heatup conditions. The boltup temperature for Seabrook is 60'F, and the limiting initial RTNDT is 30'F; therefore, the ASME reference toughness value (Kit) is 70.98 ksiv'/T. For the heatup and cooldown transient, the coolant temperature at the governing time step, near the end of heatup, is 557'F. The K1, fracture toughness for this time step is 200 ksi Viii, which is the upper shelf. The comparison of the stress intensity factors with KI, for the limiting boltup and transient conditions is given in Table 6-2.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-3 Table 6-2 Limiting Stress Intensity Factors at One-Tenth of the Wall Thickness and Fracture Toughness Values for Seabrook Unit 1 Boltup and Heatup/Cooldown Transient Conditions Transient Location K1 @ a/t = 0.10's' 2*K, @ a/t = 0 . 1 0 (b, K)ý (ksi*Win.) (ksiin.) (ksiin.)

Cut 3 Boltup Cu t (Circumferential F Flaw) 30.752 61.504 70.980 Heatup Cut 2 53.693 107.386 200(c)

(t = 344.2 minutes) (Circumferential Flaw)

Notes for Table 6-2:

(a) Limiting stress intensity factors for boltup and heatup/cooldown transient conditions.

(b) The stress intensity factors also include a safety factor of 2, which is consistent with the ASME Section XI, Appendix G requirements.

(c) Upper shelf fracture toughness value.

Using the K1 c toughness, which has now been adopted by Section XI [Reference 2] for P-T limit curves, it can be seen that there is sufficient margin between the fracture toughness and the applied stress intensity factor for both the boltup and the heatup/cooldown transient. Another objective of the requirements in Appendix G is to assure that fracture margins are maintained to protect against service induced cracking due to environmental effects. Since the governing flaw is on the outside surface (the inside is in compression) where there are no environmental effects, there is even greater assurance of fracture margin.

Furthermore, there are two possible mechanisms of degradation for this region, thermal aging and fatigue., The calculated design cumulative fatigue usage factor for this region is well below 0.1 (allowable limit is 1.0) per WCAP-16162 [Reference 8], so it may be concluded that flaws are unlikely to initiate in this region. Likewise, based on the conclusions in EPRI Report MRP-80

[Reference 3], and the discussion provided in Appendix B, thermal aging embrittlement of RPV steels used in the Seabrook Unit I closure head/flange region can be ignored as a degradation mechanism. Furthermore, the IAEA-TECDOC-1627 [Reference 7] document published by the International Atomic Energy Agency confirms that "ASME Code does not require, in principle, any evaluation of thermal ageing of RPV materials, there are also no part of RPV Surveillance specimen programme concentrated on thermal ageing effect."

Therefore, it is concluded that the integrity of the closure head/flange region is not a concern for Seabrook Unit I using the K1 c fracture toughness during the heatup/cooldown and boltup conditions.

WCAP- I7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-4 100 90 80 70 M-60

,el 50 M

40 30 20 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Flaw Depth/Wall Thickness Ratio (a/t)

Figure 6-1 Crack Driving Force as a Function of Flaw Size: Outside Surface Circumferential Flaw in the Torus to Flange Region Weld (Cut 3) for Seabrook Unit 1 October 2011 WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-5 100 90 80 70 Proj 60 50 0-0 M

40 30 20 10 0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Flaw Depth/Wall Thickness Ratio (a/t)

Figure 6-2 Crack Driving Force as a Function of Flaw Size: Outside Surface Circumferential Flaw in the Dome to Torus Region Weld (Cut 2) for Seabrook Unit 1 October 2011 17444-NP WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 7-1 7 ALTERNATIVE BOLTUP REQUIREMENTS 10 CFR Part 50, Appendix G [Reference 1] contains metal temperature requirements for the closure head/vessel flange region used in the development of the primary system pressure-temperature limits. Currently, this rule states that the metal temperature at the closure flange regions must exceed the material unirradiated RTNDT by at least 120'F for operational conditions when the pressure exceeds 20 percent of the pre-service hydrostatic test pressure, which is typically 621 psig for a PWR. The flange requirement of 10 CFR Part 50 was originally developed using the Kla fracture toughness. The goal of the evaluation contained herein is to show that with the use of the Krc fracture toughness for Seabrook along with the calculated stress intensity factor for a 0.1T postulated flaw in the reactor vessel flange region, the flange temperature requirement can be reduced or eliminated for Seabrook Unit I during the boltup conditions.

The stress intensity factors were calculated based on the stresses at the region of interest, Cuts 2 and 3, which are shown in Table 6-1, for the end of heatup, as well as the boltup conditions. The complete through-wall stresses for all time steps in the heatup and cooldown transients are provided in Appendix C.

Figure 7-1 illustrates the intersection between the fracture toughness K1 ¢curve and limiting stress intensity factor curve (with a safety factor of 2) at boltup conditions for a postulated outside surface circumferential flaw at Cut 3. This intersection point represents the alternative minimum boltup temperature requirement (T- RTNDT(U)).

250 200

  • 150 1-m 0 50 0 1t 0 50 100 150 200 T-RTNDT (1F)

Figure 7-1 Limiting Stress Intensity Factor Value at Boltup Conditions for Seabrook Unit 1 WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 7-2 Based on the stress intensity factor calculation for a ten percent through-wall thickness (0.1T) flaw, the limiting T - RTNDT for the boltup condition at the two cut locations are provided in Table 7-1. For a postulated 0.1T flaw, the limiting stress intensity factor at boltup conditions occurs at Cut 3 for a circumferentially-oriented flaw. The alternative boltup requirement (T - RTNDT(U)) is the intersection between the limiting boltup stress intensity factor with a safety factor of 2 and the Klc curve.

Table 7-1 Limiting T-RTNDT Value at Boltup Conditions for Seabrook Unit 1 K1 @ a/t = 0.1 2*K 1 @ a/t = 0.1 T-RTNDT Location Flaw Orientation (ksi'lin.) (ksiWin.) (OF)

Cut 2 Circumferential 5.051 10.102 <0 Cut 3 Circumferential 30.752 61.504 16 Based on Table 7-1 as well as Figure 7-1, the alternative boltup requirement using the Ki, fracture toughness curve for Seabrook Unit I occurs at T-RTNDT = 16'F, which is significantly less than the existing 120'F requirement per 10 CFR 50, Appendix G.

For comparison purposes, Table 7-2 provides the calculated boltup requirements for all the various vessel designs (e.g. CE, B&W, and GE) from WCAP- 15315 [Reference 9] using both Kia and KIc methodologies. It is important to note that the governing case has a boltup temperature requirement of RTNDT + 11 8°F, which closely matches the requirement of RTNDT + 120°F, which is the current requirement in 10 CFR 50, Appendix G. However, as illustrated in Table 7-2, when using Kjc methodology, the alternative boltup requirements are significantly reduced. As previously discussed, the alternative boltup requirement for Seabrook Unit I is 16*1F, which again is much lower than the current 120'F requirement.

Table 7-2 Comparison of Various Plant Designs Boltup Requirements T- RTNDT T - RTNDT Plant K, (a/t(ksilii)

= 0.1) 1 (ksia/t K(alt .)

0.1, (OF)K1a using (OF)K ,

using 1 SF=2) (a/t = 0.1) (a/t = 0.1)

CE 30.0 60.0 68 13 B&W 39.4 79.8 100 41 Seabrook 30.7 61.5 --- 16 GE (CBI 251") 38.7 77.4 97 38 GE (B&W 251 ") 48.0 96.0 118 56 GE (CE 218") 25.1 50.2 43 0*

  • The calculated value of T-RTNDT is negative, so zero is used for conservatism.

WCAP- 17444-NP October 2011 Revision 0

WESTYNGHOUSE NON-PROPREETARY CLASS 3 7-3 Per Table 4-2, the limiting initial RTNDT(U) value for the closure head/vessel flange region is 30'F for Seabrook Unit 1. Using the existing 10 CFR 50, Appendix G requirements and the limiting initial RTNDT(U) value for closure head/vessel flange region, the current limiting temperature for flange requirements in the Seabrook P-T limit curves is 1507F (120°F + 30'F) without margin for instrumentation errors.

Using the alternative boltup requirement of 16'F and the limiting initial RTNDT value for the closure head/vessel flange region of 30 0 F, the new limiting temperature for flange requirements for the Seabrook P-T limit curves is 46°F (16'F + 30'F). This alternative flange temperature requirement is much less than the current Seabrook temperature of 1,50'F. Furthermore, this alternative flange temperature requirement (46"F) is also less than the minimum boltup temperature of 60'F for Seabrook Unit I [Reference 10]. Therefore, no additional boltup requirements are necessary, and the minimum temperature for flange requirements based on 10 CFR 50, Appendix G can be completely eliminated from the P-T limit curves for Seabrook.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-1 8 REFERENCES

1. Code of Federal Regulations, 10 CFR 50, Appendix G, "Fracture Toughness Requirements," U.S.

Nuclear Regulatory Commission, Federal Register, Volume 60, No. 243, dated December 19, 1995.

2. ASME Boiler and Pressure Vessel Code, Section XI, 1998 Edition with the 2000 Addenda, ASME, New York.
3. EPRI MRP-80, "A Review of Thermal Aging Embrittlement in Pressurized Water Reactors."

Material Reliability Program, Report No. 1003523. Final Report, May 2003.

4. American Petroleum Institute, API 579-1/ASME FFS-I (API 579 Second Edition), "Fitness-For-Service," June 2007.
5. EPRI-NP-719-SR, "Flaw Evaluation Procedures, Background and Application of ASME Section XI Appendix A," August 1978.
6. Oak Ridge National Laboratory Report, ORNL/NRC/LTR-05/18, "Fracture Analysis of Vessels -

Oak Ridge FAVOR, v05.1, Computer Code: Theory and Implementation of Algorithms, Methods, and Correlations," October 2005.

7. International Atomic Energy Agency, IAEA-TECDOC-1627, "Pressurized Thermal Shock in Nuclear Power Plants: Good Practices for Assessment, Deterministic Evaluation for the Integrity of Reactor Pressure Vessel."
8. Westinghouse Document, WCAP-16162, Revision 0 (Addendum to CENC-1285), "Addendum to Combustion Engineering Inc. Report No. CENC-1285, Analytical Report for Seabrook Unit No. I Reactor Vessel, 7.4% Power Uprate Project Reactor Vessel Evaluation," November 2003.
9. Westinghouse Document, WCAP-15315, Revision 1, "Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Operating PWR and BWR Plants," April 2002.
10. Westinghouse Document WCAP-14040-A, Revision 4, "Methodology. Used to Develop Cold Overpressure Mitigating System Setpoints and RCS Heatup and Cooldown Limit Curves," May 2004.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-]

APPENDIX A REACTOR PRESSURE VESSEL INSPECTION RELIABILITY*

F. L. Becker EPRI Charlotte NC A.1 [

]ac,e Presented at the Joint EC-IAEA Technical Meeting on Improvements in Inservice Inspection Effectiveness, Pettan, The Netherlands, November 2002.

WCAP-1 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-2 A.3 [

]a~ce WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-3 A.3.1 I

]a.c,e.

a,cve Figure A-1 Probability of Detection Performance for Passed and Passed Plus Failed Candidates for Appendix VIII Supplement 4, from the Outside Surface as a function of the flaw through wall extent (TWE). Both automated and manual techniques are included.

WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-4 WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-4 a~c,e Figure A-2 POD for Inside Surface Examinations, Pass and Pass + Failed Candidates, Passed and Pass Plus Failed Candidates are included.

Table A-1 Number of Measurements ace 4 4 4 + 4 4 + +

4 + +

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-5 A.3.2 [

axce ac.e Figure A-3 Probability of Detection for Automated RPV Examinations Considering Both Inside and Outside Access. Passed and Passed Plus Failed Candidates are shown.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-6 WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-6 ace Figure A-4 POD for Pass and Failed Candidates, Considering ID and OD Automated Demonstrations and Manual OD Demonstrations.

A.4 A

Iac e WCAP- I7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-7 acre Figure A-5 Histogram of Depth Successful Sizing Candidate Test Scores, Appendix VIII, Supplement 4. Examinations Were Performed Both From the Inside and Outside Surfaces.

lace WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-8 0 [

]a,c,e a,ce Figure A-6 Sizing Error Surface Model WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-9 a,c,e Figure A-7 Plan View of Sizing Error Surface Model A.5 [

]acoe WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-10 a,ce WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-11 WESTThGHOUSE NON-PROPRJETARY CLASS 3 A-li II

]a~ce a,ce Figure A-8 Probability of Correct Sizing for Passed Candidates, Appendix VIII Supplement 4 Reporting Threshold A' = 0.15 inch.

WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-12 WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-12 a.c,e a.c.e Figure A-9 Probability of Correct Rejection/Reporting (PCR) for automated techniques, Considering Passed and Passed plus Failed Candidates, includes both inside and outside surface information. Reporting Criterion A' = 0.15 inch.

A.6

]ace WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 A-13 A.7 [

I aco WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-I APPENDIX B THERMAL AGING OF FERRITIC RPV STEELS AT REACTOR OPERATING TEMPERATURES B.1 [

]ace WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-2 II a,c~e Table B-1 Compositions of the Materials Studied by DeVan et al. [B-31 ace II

]ao~o a.ce Table B-2 T 41 J Before and After Long-Term Thermal Aging (DeVan et al. [B-3])

I

]ace WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-3 II

]3.co WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-4 II ace a,c.e Table B-3 Composition of A533B-1 Materials Studied by Williams and Ellis 1B-I1]

October 2011 17444-NP WCAP- I17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-5 ac,e Figure B-1 Plot of Vickers Hardness Versus Time for Thermal Aging at 3300 C [B-11i II I oo WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-6 I

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 B-7 B.4 A

]a,c,e WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-1 APPENDIX C STRESS DISTRIBUTIONS IN THE CLOSURE HEAD REGION C.1

]ace WCAP- I7444-NP . October 2011 Revision 0

WESUNGHOUSE NON-PROPREETARY CLASS 3 C-2 WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-2 a&c,e Figure C-1 Closure Head Region WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRJETARY CLASS 3 C-3 WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-3

-- a,c~e Figure C-2 Generic Stress Component Orientation WCAP- I7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-4 Table C-I Stress for Upper Head to Flange Transient Region (Cut 2) a,c,e 4 I.

i i 4 + I.

+ 4 4 4 + 4 4 4

+ 4 4 1* I.

4 4 WCAP-17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-5 Table C-1 Stress for Upper Head to Flange Transient Region (Cut 2) a,c,e t t

+ +

+ + +

+ + f I. I.

WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-6 Table C-1 Stress for Upper Head to Flange Transient Region (Cut 2) ace

___________________________________ ___________________________________ ___________________________________ F __________________________________

I. I.

WCAP- 17444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Tabl Table C-2 Stress for Upper Head to Flange Transient Region (Cut 3) a.ce WCAP- I 7444-NP October 2011 Revision 0 (C-73 egio Tansint lane to pperHea orStrss C-

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-8 WESTINGHOUSE NON-PROPRWTARY CLASS 3 C-8 ace WCAP- I 7444-NP October 2011 Revision 0

WESTINGHOUSE NON-PROPRIETARY CLASS 3 C-9 Table C-2 Stress for Upper Head to Flange Transient Region (Cut 3) a,c,e WCAP- 17444-NP October 2011 Revision 0

Attachment 6 Affidavit for Withholding Proprietary Information from Public Disclosure

Westinghouse Electric Company

  • Westinghouse Nuclear Services 1000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA U.S. Nuclear Regulatory Commission Direct tel: (412) 374-4643 Document Control Desk Direct fax: (724) 720-0754 11555 Rockville Pike e-mail: greshaja@westinghouse.com Rockville, MD 20852 Proj letter: NAH- 12-7 CAW-12-3366 January 23, 2012 APPLICATION FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE

Subject:

WCAP-17444-P, Revision 0, "Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Seabrook Unit 1" (Proprietary)

The proprietary information for which withholding is being requested in the above-referenced report is further identified in Affidavit CAW-12-3366 signed by the owner of the proprietary information, Westinghouse Electric Company LLC. The affidavit, which accompanies this letter, sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of 10 CFR Section 2.390 of the Commission's regulations.

Accordingly, this letter authorizes the utilization of the accompanying affidavit by NextEra Energy.

Correspondence with respect to the proprietary aspects of the application for withholding or the Westinghouse affidavit should reference this letter, CAW-12-3366, and should be addressed to J. A. Gresham, Manager, Regulatory Compliance, Westinghouse Electric Company, Suite 428, 1000 Westinghouse Drive, Cranberry Township, Pennsylvania 16066.

Very truly yours, A. Gresham, Manager Regulatory Compliance Enclosures

CAW-12-3366 AFFIDAVIT COMMONWEALTH OF PENNSYLVANIA:

ss COUNTY OF BUTLER:

Before me, the undersigned authority, personally appeared J. 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:

A. Gresham, Manager Regulatory Compliance Sworn to and subscribed before me this 23rd day of January 2012 Notary Public COMMONWEALTH OF PENNSYLVANIA Notarial Seal Cynthia Olesky, Notary Public Manor Born, Westmoreland County My Commission Expires July 16, 2014 Member. Pennsvlvania Association of Notaries

2 CAW-1 2-3366 (1) I 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-1 2-3366 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-12-3366 (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 WCAP- I7444-P, Revision 0, "Reactor Vessel Closure Head/Vessel Flange Requirements Evaluation for Seabrook Unit 1" (Proprietary) dated October 2011, for submittal to the Commission, being transmitted by NextEra 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 technical justification to support the elimination of the flange requirement when developing pressure-temperature limits for the Seabrook Unit I reactor vessel, and may be used only for that purpose.

5 CAW-12-3366 This information is part of that which will enable Westinghouse to:

(a) Provide documentation of the analyses and methods used to show that the use of the K1. fracture toughness for the reactor vessel closure head flange region leads to the conclusion that the flange requirement specified in 10 CFR 50, Appendix G can be eliminated for Seabrook Unit 1.

(b) Assist the customer to respond to NRC requests for information.

Further this information has substantial commercial value as follows:

(a) Westinghouse plans to sell the use of similar information to its customers for the purpose of providing technical justification to support the elimination of the flange requirement when developing pressure-temperature limits for the reactor vessel.

(b) Westinghouse can sell support and defense of the technology to its customer in the licensing process.

(c) 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 calculations 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.

6 CAW-12-3366 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.

PROPRIETARY INFORMATION NOTICE Transmitted herewith are proprietary and/or non-proprietary versions of documents furnished to the NRC in connection with requests for generic and/or plant-specific review and approval.

In order to conform to the requirements of 10 CFR 2.390 of the Commission's regulations concerning the protection of proprietary information so submitted to the NRC, the information which is proprietary in the proprietary versions is contained within brackets, and where the proprietary information has been deleted in the non-proprietary versions, only the brackets remain (the information that was contained within the brackets in the proprietary versions having been deleted). The justification for claiming the information so designated as proprietary is indicated in both versions by means of lower case letters (a) through (f) located as a superscript immediately following the brackets enclosing each item of information being identified as proprietary or in the margin opposite such information. These lower case letters refer to the types of information Westinghouse customarily holds in confidence identified in Sections (4)(ii)(a) through (4)(ii)(f) of the affidavit accompanying this transmittal pursuant to 10 CFR 2.390(b)(1).

COPYRIGHT NOTICE The reports transmitted herewith each bear a Westinghouse copyright notice. The NRC is permitted to make the number of copies of the information contained in these reports which are necessary for its internal use in connection with generic and plant-specific reviews and approvals as well as the issuance, denial, amendment, transfer, renewal, modification, suspension, revocation, or violation of a license, permit, order, or regulation subject to the requirements of 10 CFR 2.390 regarding restrictions on public disclosure to the extent such information has been identified as proprietary by Westinghouse, copyright protection notwithstanding. With respect to the non-proprietary versions of these reports, the NRC is permitted to make the number of copies beyond those necessary for its internal use which are necessary in order to have one copy available for public viewing in the appropriate docket files in the public document room in Washington, DC and. in local public document rooms as may be required by NRC regulations if the number of copies submitted is insufficient for this purpose. Copies made by the NRC must include the copyright notice in all instances and the proprietary notice if the original was identified as proprietary.

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