ML18334A268

WCAP-18295-NP, Revision 0, Technical Justification for Eliminating Accumulator Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using Leak-Before-Break Methodology (Non-Proprietary)

ML18334A268
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Site:	Cook
Issue date:	01/31/2018
From:	Kirby C R Westinghouse
To:	Office of Nuclear Reactor Regulation
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ML18334A291	List: AEP-NRC-2018-66, Request for License Amendment to Technical Specification 3.4.15, RCS Leakage Detection Instrumentation, and Application of Leak-Before-Break Methodology ML18334A268 ML18334A269 ML18334A270
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AEP-NRC-2018-66 WCAP-18295-NP
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Enclosure 9 to AEP-NRC-2018-66 WCAP-18295-NP, Revision O "Technical Justification for Eliminating Accumulator Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using

• Leak-Before-Break Methodology" (Non-Proprietary)

• • -~-WCAP-18295-NP Revision 0 WESTINGHOUSE NON-PROPRIETARY CLASS 3 Technical Justification for Eliminating Accumulator Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using Leak-Before-Break Methodology . @ Westinghouse January 2018 *** This record was final appr_o_ved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-18295-NP Revision 0 Technical Justification for Eliminating Accumulator Line Rupture as the Structural Design Basis for D.C. Cook Units-1 and 2, Using Leak-Before-Break Methodology January 2018 Author: Christopher R. Kirby* Structural Design and Analysis -I Reviewer:

Eric D. Johnson* Structural Design and Analysis -II

• Approved:

Benjamin A. Leber, Manager* . Structural Design and Analysis -II *Electronically approved records are authenticated in the electronic document management system. Westinghouse Electric Company LLC 1000 Westinghouse Drive Cranberry Township, PA 16066, USA © 2018 Westinghouse Electric Company LLC . All Rights Reserved *** This record was final approved on 1/18/2018 9:40:03 AM. (Jhis.statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 111 TABLE OF CONTENTS 1.0 Introduction

........................................................................................................................................

1-l 1.1 Purpose .................................................................................................................................

1-l 1.2 Scope and Objectives

............................................................................................................

1-l 1.3 References

.............................................................................................................................

1-2 2.0 Operation and Stability of the Reactor Coolant System ********:************;

..............................................

2-l 2.1 Stress Corrosion Cracking ........................................................................

...........................

2-l 2.2 Water Hammer ......................................................................................................................

2-2 2.3 Low Cycle and High Cycle Fatigue ......................................................................................

2-2 2.4 Other Possible Degradation During Service of the Accumulator Lines ....... , .......................

2-3 2.5 References

.............................................................................................................................

2-3 3.0 Pipe Geometry and Loading ..............................................................................................................

3-l 3 .1 Calculations of Loads and Stresses .......................................................................................

3-1 3.2 Loads for Leak Rate Evaluation

...........................................................................................

3-l 3.3 Load Combination for Crack Stability Analyses ..................................................................

3-2 3.4 References

.............................................................................................................................

3-3 4.0 Material Characterization

...................................................................................................................

4-l 4.1 Accumulator Line Pipe Material and Weld Process ****:********

...............................................

.4-l 4.2 Tensile Properties

..................................................................................................................

4-l 4.3 Reference

................................................................................................

'. .............................

4-1 5.0 Critical Locations

...............................................................................................................................

5-l. 5 .1 Critical Locations

..................................................................................................................

5-1 6.0 Leak Rate Predictions

........................................................................................................................

6-1 6.1 Introduction

...........................................................................................................................

6-1 6.2 General Considerations

.........................................................................................................

6-1 6.3 Calculation Method ...............................................................................................................

6-1 6.4 Leak Rate Calculations

.........................................................................................................

6-2 6.5 References

.............................................................................................................................

6-3 7.0 Fracture Mechanics Evaluation

..........................................................................................................

7-1 7 .1 Global Failure Mechanism

....................................................................................................

7-1 7.2 Local Failure Mechanism

.....................................................................................................

7-2 7.3 Results of Crack Stability Evaluation

...................................................................................

7-2 7.4 References

.............................................................................................................................

7-2 8.0 Assessment of Fatigue Crack Growth ................................................................................................

8-1 8 .1 References

.............................................................................................................................

8-1 9 .0 Assessment of Margins ......................................................................................................................

9-1 10.0 Conclusions

......................................................................................................................................

l 0-1 Appendix A: Limit MOIIlent ....... ; .. : .........................

.....................................................................................

A-1 WCAP-18295-NP . . . . . January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 LIST OF TABLES Table 3-1 Summary ofD.C. Cook Unit 1 Piping Geometry and Normal Operating Condition for IO-inch Accumulator Lines .......................................................................

3-4 Table 3-2 Summary ofD.C. Cook Unit 2 Piping Geometry and Normal Operating Condition for IO-inch Accumulator Lines .......................................................................

3-5 Table 3-3 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop l .................................................................................

3-6 Table 3-4 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 .................................................................................

3-7 Table 3-5 ** Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 .................................................................................

3-8 Table 3-6 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 .................................................................................

3-9 Table 3-7 Summary of D.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop l ...............................................................................

3-10 Table 3-8 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 ...............................................................................

3-l l Table 3-9 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 ...............................................................................

3-12 Table 3-10 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 ...............................................................................

3-13 Table 3-11 Summary of D.C. Cook Unit 1 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop l ...............................................................................

3-14 Table 3-12 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for IO-inch Accumulator Injection Line Loop 2 ..............................................................................

.3-15 Table 3-13 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for IO-inch Accumulator Injection Line Loop 3 ...............................................................................

3-16 Table 3-14 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 ...............................................................................

3-17 Table 3-15 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for IO-inch Accumulator Injection Line Loop l ...............................................................................

3-18 Table 3-16 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for IO-inch Accumulator Injection Line Loop 2 ...............................................................................

3-19 Table3-l7*'

• Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for IO-inch Accumulator Injection Line Loop 3 ........................................... ...................................

3-20 WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation) iv Table3-18 Table 4-1 Table 5-1 Table 6-1 Table 7-1 Table 9-1 WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3 Summary of D.C. Cook Unit 2 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 ...............................................................................

3-21 Mechanical Properties for IO-inch Accumulator Lines Material at Operating Temperatures for D.C. Cook Units 1 and 2 .....................................................................

.4-1 Summary ofD.C. Cook Unit 1 Piping Geometry and Normal Operating Condition for IO-inch Accumulator Lines and Critical Locations

...................................

5-1 Flaw Sizes Yielding a Leak Rate of 8 gpm for the D.C. Cook Unit 1 and 2 10-inch Accumulator Lines ...................................................................................................

6-3 Stability Results for the D.C. Cook Unit 1 and 2 10-inchAccumulator Lines Based on Limit Load ........................................................................................................

7-3 Leakage Flaw Sizes, Critical Flaw Sizes and Margins for D.C. Cook Units 1 and 2 10-inch Accumulator Lines ...........................................................................................

9-1 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

V Figure 3-1 Figure 3-2 Figure 3-3 Figure 3-4 Figure 3-5 Figure 3-6 Figure 3-7 Figure 3-8 Figure 3-9 Figure 5-1 Figure 5-2 Figure 5-3 Figure 6-1 Figure 6-2 Figure 6-3 Figure 7-1 WESTINGHOUSE NON-PROPRIETARY CLASS 3 LIST OF FIGURES 10-inch Accumulator Line Layout Showing Segments for D.C. Cook Units 1 and 2 ...............................................................................................................................

3-22 D.C. Cook Unit 1 Accumulator Line Loop 1 Layout Showing Weld Locations with Node Points ............................................................................................................

3-23 D.C. Cook Unit 1 Accumulator Line Loop 2 Layout Showing Weld Locations . with Node Points .........................................................

..................................................

3-24 D.C. Cook Unit 1 Accumulator Line Loop 3 Layout Showing Weld Locations with Node Points ............................................................................................................

3-25 D.C. Cook Unit 1 Accumulator Line Loop 4 Layout Showing Weld Locations with Node Points ............................................................................................................

3-26 D.C. Cook Unit 2 Accumulator Line Loop 1 Layout Showing Weld Locations with Node Points ............................................................................................................

3-27 D.C. Cook Unit 2 Accumulator Line Loop 2 Layout Showing Weld Locations with Node Points ............................................................................................................

3-28 D.C. Cook Unit 2 Accumulator Line Loop 3 Layout Showing Weld Locations with Node Points ............................................................................................................

3-29 D.C. Cook Unit 2 Accumulator Line Loop 4 Layout Showing Weld Locations with Node Points ............................................................................................................

3-30 Layout Showing Critical Location Loop 4 Unit 2 ...........................................................

5-2 Layout Showing Critical Locations Loop 3 Unit 2 ..........................................................

5-3 Layout Showing Critical Locations Loop 1 Unit 2 ..........................................................

5-4 Analytical Predictions of Critical Flow Rates of Steam-Water Mixtures .......................

6-4 ]",c,e Pressure Ratio as a Function ofL/D ....................................................

6-5 Idealized Pressure Drop Profile Through a Postulated Crack ..........................................

6-6 ]",c,e Stress Distribution

....................................................................................

7-4 Figure A-1 Pipe with a Through-Wall Crack in Bending ................................................................

A-2 WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation) vi WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-1

1.0 INTRODUCTION

1.1 PURPOSE

The current structural design basis for the D.C. Cook Units 1 and 2 10-inch accumulator lines (from the cold legs Loop 1, Loop 2, Loop 3 and Loop 4) require postulating non-mechanistic circumferential and longitudinal pipe breaks. This results in additional plant hardware ( e.g., pipe whip restraints and jet shields) which would mitigate the dynamic consequences of the pipe breaks. It is, therefore, highly desirable to be realistic in the postulation of pipe breaks for the accumulator lines. Presented in this. report are the descriptions of a mechanistic pipe break evaluation method and the analytical results that can be used for establishing that a circumferential type of break will not occur within the accumulator lines. The evaluations consider that circumferentially oriented flaws cover longitudinal cases. 1.2 SCOPE AND OBJECTIVES The purpose of this investigation is to demonstrate Leak Before Break (LBB) for the D.C. Cook Units 1 and 2 accumulator lines from the cold legs Loop 1, Loop 2, Loop 3 and Loop 4 to the isolation valves near the accumulator tanks. Schematic drawings of the piping system are shown in Section 3.0. The recommendations and criteria proposed in SRP 3.6.3 (References 1-1 and 1-2) are used in this evaluation.

The criteria and the resulting steps of the evaluation procedure can be briefly summarized as follows: I. Calculate the applied loads based on as-built configuration.

Identify the location(s) at which the highest faulted stress occurs. 2. Identify the materials and the material properties.

3. Postulate a through-wall flaw at the governing location(s).

The size of the flaw should be large enough so that the leakage is assured of detection with margin using the installed leak detection equipment when the pipe is subjected to normal operating loads. Demonstrate that there is a margin of 10 between the calculated leak rate and the leak detection capability.

4. Using maximum faulted loads in the stability

'analysis, demonstrate that there is a margin of 2 between the leakage size flaw and the critical size flaw. 5. Review the operating history to ascertain that operating experience has indicated no particular susceptibility to failure from the effects of corrosion, water hammer, or low and high cycle fatigue. 6. For the mate_rial types used in the plant, provide representative material properties.

7. Demonstrate margin on applied load by combining the faulted loads by absolute summation method. This report provides a fracture mechanics demonstration of accumulator line piping integrity for D.C. Cook Units 1 and 2 consistent with the NRC's position for exemption from consideration of dynamic effects (Reference 1-3). Introduction WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-2 It should be noted that the terms "flaw" and "crack" have the same meaning and are used interchangeably. "Governing location" and "critical location" are also used interchangeably throughout the report. *

1.3 REFERENCES

1-1 Standard Review Plan: Public Comments Solicited; 3.6.3 Leak-Before-Break Evaluation Procedures; Federal RegisterNol.

52, No. 167/Friday August 28, 1987/Notices, pp. 32626-32633.

1-2 NUREG-0800 Revision 1, March 2007, Standard Review Plan: 3.6.3 Leak-Before-Break Evaluation Procedures.

1-3 Nuclear Regulatory Commission, 10 CFR 50, Modification of General Design Criteria 4 Requirements for Protection Against Dynamic Effects of Postulated Pipe Ruptures, Final Rule, Federal RegisterNol.

52, No. 207/Tuesday, October 27, 1987/Rules and Regulations, pp. 41288-41295.

Introduction WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-1 2.0 OPERATION AND STABILITY*OF THE REACTOR COOLANT SYSTEM 2.1 STRESS CORROSION CRACKING The Westinghouse reactor coolant system primary loops and connected Class 1 piping have an operating history that demonstrates the inherent operating stability characteristics of the design. This includes a low susceptibility to cracking failure from the effects of corrosion ( e.g., intergranular stress corrosion cracking (IGSCC)).

This operating history totals over 1400 reactor-years, including 16 plants each having over 30 years of operation, 10 other plants each with over 25 years of operation, 11 plants each with over 20 years of operation and 12 plants each with over 15 years of operation.

In 1978, the United States Nuclear Regulatory Commission (USNRC) formed the second Pipe Crack Study Group. (The first Pipe Crack Study Group (PCSG) established in 1975 addressed cracking in boiling water reactors only.) One of the objectives of the second PCSG was to include a review of the potential for stress corrosion cracking in Pressurized Water Reactors (PWRs ). The results of the study performed by the PCSG were presented in NUREG-0531 (Reference 2-1) entitled "Investigation and Evaluation of Stress Corrosion Cracking in Piping of Light Water Reactor Plants." In that report the PCSG stated: "The PCSG has determined that the potential for stress-corrosion cracking in PWR primary system piping is extremely low because the ingredients that produce IGSCC are not all present. The use of hydrazine additives and a hydrogen overpressure limit the oxygen in the coolant to very low levels. Other impurities that might cause stress-corrosion cracking, such as halides or caustic, are also rigidly controlled.

Only for brief periods during reactor shutdown when the coolant is exposed to the air and during the subsequent startup are conditions even marginally capable of producing stress-corrosion cracking in the primary systems of PWRs. Operating experience in PWRs supports this determination.

To date, no stress corrosion cracking has been reported in the primary piping or safe ends of any PWR." For stress corrosion cracking (SCC) to occur in piping, the following three .conditions must exist simultaneously:

high tensile stresses, susceptible material, and a corrosive environment.

Since some residual stresses and some degree of material susceptibility exist in any stainless steel piping, the potential for stress corrosion is minimized by properly selecting a material immune to SCC as well as preventing the occurrence of a corrosive environment.

• The material specifications consider compatibility with the system's operating environment (both internal and external) as well as* other material in the system, applicable ASME Code rules, fracture toughness, welding, fabrication, and processing.

The elements of a water environment known to increase the susceptibility of austenitic stainless steel to stress corrosion are: oxygen, fluorides, chlorides, hydroxides, hydrogen peroxide, and reduced forms of sulfur (e.g., sulfides, sulfites, and thionates).

Strict pipe cleaning standards prior to operation and careful control of water chemistry during plant operation are used to prevent the occurrence of a corrosive environment.

Prior to being put into service, the piping is cleaned internally and externally.

During flushes and preoperational testing, water chemistry is controlled in accordance with written specifications.

Operation and Stability of the Reactor Coolant System WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-2 Requirements on chlorides, fluorides, conductivity, and pH are included in the acceptance criteria for the piping. During plant operation, the reactor coolant water chemistry is monitored and maintained within very specific limits. Contaminant concentrations are kept below the thresholds known to be conducive to stress corrosion cracking with the major water chemistry control standards being included in the plant operating procedures as a condition for plant operation.

For example, during normal power operation, oxygen concentration in the RCS is expected to be in the parts per billion (ppb) range by controlling charging flow chemistry and maintaining hydrogen in the reactor coolant at specified concentrations.

Halogen concentrations are also stringently controlled by maintaining concentrations of chlorides and fluorides within the specified limits. Thus during plant operation, the likelihood of stress corrosion cracking is minimized.

• During 1979, several instances of cracking in PWR feedwater piping led to the establishment of the third PCSG The investigations of the PCSG reported in NUREG-0691 (Reference 2-2) further confirmed that no occurrences ofIGSCC have been reported for PWR primary coolant systems . . Primary Water Stress Corrosion Cracking (PWSCC) occurred in V. C. Summer reactor vessel hot leg nozzle, Alloy 82/182 weld. It should be noted that this susceptible material is not found in the D.C. Cook Unit 1 and 2 accumulator lines. 2.2 WATERHAMMER Overall, there is a low potential for water hammer in the RCS and connecting accumulator lines since they are designed and operated to preclude the voiding condition in normally filled lines. The RCS and connecting accumulator lines including piping and components are designed for normal, upset, emergency, and faulted condition transients.

The design requirements are conservative relative to both the number of transients and their severity.

Relief valve actuation and the associated hydraulic transients following valve opening are considered in the system design. Other valve and pump actuations are relatively slow transients with no significant effect on the system dynamic loads. To ensure dynamic system stability, reactor coolant parameters are stringently controlled.

Temperature during normal operation is maintained within a narrow range by the control rod positions; pressure is controlled also within a narrow range for steady-state conditions by the pressurizer heaters and pressurizer spray. The flow characteristics of the system remain constant during a fuel cycle because the only governing parameters, namely system resistance and the reactor coolant pump characteristics are controlled in the design process. Additionally, Westinghouse has instrumented typical reactor coolant systems to verify the flow and vibration characteristics of the system and the connecting auxiliary lines. Preoperational testing and operating experience has verified the Westinghouse approach.

The operating transients of the RCS primary piping and connected accumulator lines are such that no significant water hammer can occur. 2.3 LOW CYCLE AND HIGH CYCLE FATIGUE The 1967 Edition of the B3 l. l Code does not contain an explicit piping low cycle fatigue analysis requirement.

The B31. l piping complies with a stress range reduction factor to be applied to the allowable stress as a way to address fatigue from full temperature cycles for thermal expansion stress evaluation.

The stress range reduction factor is 1.0 (i.e., no reduction) for equivalent full temperature Operation and Stability of the Reactor Coolant System WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 2-3 cycles less than 7000. For D.C. Cook Units 1 and 2, the equivalent full temperature cycles for the applicable design transients are less than 7000, so no reduction is required.

Pump vibrations during operation would result in high cycle fatigue loads in the piping system. During operation, an alarm signals the exceedance of the RC pump shaft vibration limits. Field vibration measurements have been made on the reactor coolant loop piping in a number of plants during hot functional testing. Stresses in the elbow below the RC pump have been found analytically to be very small, between 2 and 3 ksi at the highest. Field measurements on typical PWR plant indicate vibration stress amplitudes less than 1 ksi. When translated to the connecting accumulator lines, these stresses would be even lower, well below the fatigue endurance limit for the accumulator line materials and would result in an applied stress intensity factor below the threshold for fatigue crack growth. 2.4 OTHER POSSIBLE DEGRADATION DURING SERVICE OF THE ACCUMULATOR LINES The accumulator lines and the associated fittings for D.C. Cook Nuclear Power Plants are forged product forms, which are not susceptible to toughness degradation due to thermal aging. The maximum normal operating temperature of the accumulator piping is about 549°F. This is well below the temperature that would cause any creep damage in stainless steel piping. Cleavage type failures are not a concern for the operating temperatures and the material used in the stainless steel piping of the accumulator lines. Wall thinning by erosion and erosion-corrosion effects should not occur in the accumulator piping due to the low velocity, typically less than 1.0 ft/sec and the stainless steel material, which is highly resistant to these degradation mechanisms.

Per NUREG-0691 (Reference 2-2), a study on pipe cracking in PWR piping reported only two incidents of wall thinning in stainless steel pipe and these were not in the accumulator line. The cause of wall thinning is related to the high water velocity and is therefore clearly not a mechanism that would affect the accumulator piping. Brittle fracture for stainless steel material occurs when the operating temperature is about -200°F. Accumulator line operating temperature is higher than 120°F and therefore, brittle fracture is not a concern for the accumulator line.

2.5 REFERENCES

2-1

• Investigation and Evaluation of Stress-Corrosion Cracking in Piping of Light Water Reactor Plants, NUREG-0531, U.S. Nuclear Regulatory Commission, February 1979. 2-2 Investigation and Evaluation of Cracking Incidents in Piping in Pressurized Water Reactors, NUREG-0691, U.S. Nuclear Regulatory Commission, September 1980. Operation and Stability of the Reactor Coolant System WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3.0 PIPE GEOMETRY AND LOADING 3.1 CALCULATIONS OF LOADS AND STRESSES The stresses due to axial loads and bending moments are calculated by the following equation:

where, cr F M A z F M cr = -+ A Z stress (psi) axial load (lbs) moment (in-lb) pipe cross-sectional area (in 2) section modulus (in 3) The moments for the desired loading combinations are calculated by the following equation:

M = ~M 2+M 2+M 2 X y Z where, Mx X component of moment, Torsion My Y component of bending moment Mz Z component of bending moment 3-1 (3-1) (3-2) The axial load and moments for leak rate predictions and crack stability analyses are computed by the methods to be explained in Sections 3.2 and 3.3. 3.2 LOADS FOR LEAK RATE EVALUATION The normal operating loads for leak rate predictions are calculated by the following equations:

F = Fnw + Fru+fp (3-3) Mx (Mx)nw + CMx}rn (3-4) My (My)nw + (My)ru (3-5) Mz = (Mz)nw + (Mz)ru (3-6) Pipe Geometry and Loading January 2018 WCAP-18295-NP .Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-2 The subscripts of the above equations represent the following loading cases: DW deadweight TH normal thermal expansion P load due to internal pressure This method of combining loads is often referred to as the algebraic sum method (References 3-1 and 3-2). The LBB evaluations do not include moment effects due to pressure loading since the moment loading is significantly dominated by the thermal loads for normal operation and by the seismic loads for faulted events. The dimensions and normal operating conditions are given in Tables 3-1 and 3-2. The loads based on this method of combination are provided in Tables 3-3 to 3-10 at all the weld locations.

The weld naming convention used in this report is as follows: Unit# -Isometric # -Spool Sheet# -Analysis Node # 3.3 LOAD COMBINATION FOR CRACK STABILITY ANALYSES In accordance with Standard Review Plan 3.6.3 (References 3-1 and 3-2), the absolute sum of loading components can be applied which results in higher magnitude of combined loads. If crack stability is demonstrated using these loads, the LBB margin on loads can be reduced from -V2 to 1.0. The absolute summation of loads is shown in the following equations:

F = I Fnw I+ I Fru I+ I Fp I+ I FssEINERTIA I+ I FssEAM I Mx = I (Mx)nw I + I (Mx)TH I + I (Mx)ssEINERTIAJ + I (Mx)ssEAMJ My= I (My)nw I+ I (My)ru I+ I (My)ssEINERTIAJ + I (My)ssEAMJ Mz = I (Mz)nw I + I (Mz)ru I + I (Mz)ssEINERTIAJ + I (Mz)ssEAMJ (3-7) (3-8) (3-9) (3-10) where subscript SSEINERTIA refers to safe shutdown earthquake inertia, SSEAM is safe shutdown earthquake anchor motion. It is noted that the D.C. Cook piping analyses consider Design Basis Earthquake (DBE) as the seismic criteria, which is equivalent to Safe Shutdown Earthquake (SSE). The loads so determined are use'd in the fracture mechanics evaluations (Section 7 .0) to demonstrate the LBB margins at the locations established to be the governing locations.

These loads at all the weld locations are given in Tables 3-11 to 3-18. Notes: For the accumulator lines, the LBB analysis will not be performed at the locations after the isolation valve near the accumulator tank since any break after the isolation valve will not have any effect on the primary loop piping system since there are two check valves, and the one isolation valve will Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-3 prevent the break propagation to the primary loop piping system. Figure 3-1 shows typic~ 10-inch accumulator line. layout showing segments for D.C. Cook Units 1 and 2.

3.4 REFERENCES

3-1 Standard Review Plan: Public Comments Solicited; 3.6.3 Leak-Before-Break Evaluation Procedures; Federal RegisterNol.

52, No. 167/Friday, August 28, 1987/Notices, pp. 32626-32633.

3-2 NUREG-0800 Revision 1, March 2007, Standard Review Plan: 3.6.3 Leak-Before-Break Evaluation Procedures.

Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 ***. This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-4 Table 3-1 Summary ofD.C. Cook Unit 1 Piping Geometry and Normal Operating Condition for 10-inch Accumulator Lines Minimum Normal Operating Pipe Size & Wall Loop Segment Nodes Material Type Schedule Thickness Pressure Temperature (in) (psig) (OF) I 416 to 412 A376 TP316 or IO-inch 0.896 2345 549 A403 WP316 Sch. 140 406-404 A376 TP316 or IO-inch 0.896 2235 549 A403 WP316 Sch. 140 1 II A376 TP316 or 404 to 450 IO-inch 0.896 2235 120 A403 WP316 Sch. 140 III 456 to 459 A376 TP316 or IO-inch 0.896 644 120 A403 WP316

• Sch. 140 I 361 to 358 A376 TP316 or IO-inch 0.896 2345 549 A403 WP316 Sch. 140 352 to 350 A376 TP316 or IO-inch 0.896 2235 549 A403 WP316 Sch. 140 2 II A376 TP316 or 350 to 365 IO-inch 0.896 2235 120 A403 WP316 Sch. 140 III 368 to 374 A376 TP316 or IO-inch 0.896 644 120 A403 WP316 Sch. 140 I 171 to 168 A376 TP316 or IO-inch 0.896 2345 549 A403 WP316 Sch. 140 162 to 160 A376 TP316 or IO-inch 0.896 2235 549 A403 WP316 Sch. 140 3 II A376 TP316 or 160 to 200 IO-inch 0.896 2235 120 A403 WP316 Sch. 140 III 206 to 214 A376 TP316 or IO-inch 0.896 644 120 A403 WPSI6 Sch. 140 .. I 307 to 304 A376 TP316 or IO-inch 0.896 2?45 549 A403 WP316 Sch. 140 296 to 294 A376 TP316 or IO-inch 0.896 2235 549 A403 WP316 Sch. 140 4 II A376 TP316 or 294 to 334 IO-inch 0.896 2235 120 A403 WP316 Sch. 140 III 340 to 344 A376 TP316 or IO-inch 0.896 644 120 A403 WP316 Sch. 140 Notes: Pipe Outer Diameter=

10.75 in. Figure 3-1 shows the Segments.

Node numbers are shown in Tables 3-3 to 3-6, Tables 3-11 to 3-14, and Figures 3-2 to 3-5. The minimum wall thickness is conservatively based at the weld counterbore and not per ASME Code requirement.

Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 ***This.record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-5 Table 3-2 Summary ofD.C. Cook Unit 2 Piping Geometry and Normal Operating Condition for 10-inch Accumulator Lines Minimum Normal Operating Pipe Size & Wall Loop Segment Nodes Material Type Schedule Thickness Pressure Temperature (in) (psig) (OF) I 416 to 412 A376 TP316 or 10-inch 0.896 2345 549 A403 WP316 Sch. 140 406-404 A376 TP316 or 10-inch 0.896 2235 549 A403 \VP316 Sch. 140 1 II A376 TP316 or 404 to 450 10-inch 0.896 2235 120 A403 WP316 Sch. 140 III 456 to 460 A376 TP316 or 10-inch 0.896 644 120 A403 WP316 Sch. 140 I 361 to 358 A376 TP316 or 10-inch 0.896 2345 549 A403 WP316 Sch. 140 352 to 350 A376 TP316 or 10-inch 0.896 2235 549 A403 WP316 Sch. 140 2 II A376 TP316 or 350 to 365 10-inch 0.896 2235 120 A403 WP316 Sch. 140 III 368 to 374 A376 TP31~ or 10-inch 0.896 644 120 A403 WP3,16 Sch. 140 I 171 to 16,8 A376 TP316 or 10-inch 0.896 2345 549 A403 WP316 Sch. 140 162 to 160 A376 TP316 or 10-inch 0.896 2235 549 A403 WP316 Sch. 140 3 II A376 TP316 or 160 to 200 10-inch 0.896 2235 120 A403 WP316 Sch. 140 III 206 to 214 A376 TP316 or 10-inch 0.896 644 120 A403 WP316 Sch. 140 I 307 to 304 A376 TP316 or 10-inch 0.896 2345 549 A403 WP316 Sch. 140 296 to 294 A376 TP316 or 10-inch 0.896 2235 549 A403 WP316 Sch. 140 4 II 294 to 334 A376 TP316 or 10-inch 0.896 2235 120 A403 WP316 Sch. 140 III 340 to 344 A376 TP316 or 10-inch 0.896 644 120 A403 WP316 Sch. 140 Notes: Pipe Outer Diameter=

10.75 in. Figure 3-1 shows the Segments.

Node numbers are shown in Tables 3-7 to 3-10, Tables 3-15 to 3-18, and Figures 3-6 to 3-9. The minimum wall thickness is conservatively based at the weld counterbore and not per ASME Code requirement.

Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table3-3 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 1 Weld Location Axial Force Node (lbs) 1-SI-29-4-416 150,544 1-SI-29-4-412 151,904 1-SI-29-3R-406 144,981 1-SI-29-3R-404Y 144,974 1-SI-29-3R-404Z 144,603 1-S1-29-3R-420N 145,021 1-SI-29-3R-420F.

132,866 1-S1-29-2-426N 132,866 l-SI-29-2-426F 135,542 1-SI-29-2-428N 135,361 1-S1-29-2-428F 134,368 1-SI-29-2-430N 133,973 1-SI-29-2-430F 134,456 1-SI-29-2-434N 133,786 1-SI-29-1-434F 132,348 1-SI-29-1-442N 140,744 1-SI-29-1-446F 144,828 1-SI-29-1-450 144,385 1-SI-28-1-456 42,094 1-SI-28-1-459 40,082 Notes:

• See Figure 3-2

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 572,540 480,244 372,401 359,707 329,751 138,676 302,148 610,416 584,316 511,059 418,866 187,196 217,782 596,012 606,825 19,109 24,490 36,111 48,043 75,149 Total Stress (psi) 14,500 13,087 11,129 10,927 10,439 7,428 9,579 14,462 14,145 12,978 11,482 7,798 8,300 14,267 14,386 5,379 5,612 5,780 2,279 2,636 3-6 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-7 . Table 3-4 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 Weld Location Axial Force Node (lbs) 1-SI-31-4-361 150,050 1-SI-31-4-358 150,454 1-SI-31-3R-352 143,522 1-SI-31-3R-350X 143,515 1-SI-31-3R-350Z 137,879 1-SI-3 l-3R-348F 137,317 1-SI-31-3R-348N 148,662 1-SI-31-3R-344F 148,661 1-SI-31-2-344N 145,839 1-SI-31-2-342F 146,048 1-SI-31-2-342N 146,006 1-SI-31-2-340F 146,140 1-SI-31-2-340N 146,570 1-SI-31-1A-338F 147,466 1-SI-31-1A-338N 148,841 l-SI-31-1A-332F 141,852 1-SI-31-1A-332N 140,753 1-SI-31-1A-330F 140,754 1-SI-31-lA-324 141,694 1-SI-31-1A-324Y 144,566 1-Sl-3 l-lA-365 144,181 1-SI-30-1-369N 41,878 1-Sl-30-1-372F 40,592 1-Sl-30-1-374 40,592 Notes:

• See Figure 3-3

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 553,834 464,800 360,126 349,881 329,396 146,068 305,946 583,194 543,364 429,755 341,910 228,057 173,557 601,975 __ 616,807 49,529 34,468 34,318 60,896 42,505 38,709 33,833 43,134 56,445 Total Stress (psi) 14,186 12,790 10,882 10,719 10,191 7,267 10,209 14,601 13,868 12,076 10,683 8,884 8,036 14,855 15,139 5,901 5,623 5,621 6,076 5,888 5,814 2,046 2,147 2,358 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-5 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 Weld Location Axial Force Node (lbs) 1-SI-33-4-171 149,402 1-SI-33-4-168 149,924 1-SI-33-3R-162 142,990 1-SI-33-3R-160Y 142,990 l~SI-33-3R-160Z 144,283 1-SI-33-3R-174N 144,756. 1-SI-33-3R-174F 132,912 1-SI-33-3R-178N 132,912 1-SI-33-2-178F 135,855 1-SI-33-2-ISON 135,647 1-SI-33-2-1 SOF 135,829 1-SI-33-2-182N 135,715 1-SI-33-2-182F 135,186 1-SI-33-2-184N 134,254 1-SI-33-1A-184F 132,807 1-SI-33-1A-190N 140,752 1-SI-33-IA-196 140,684 l-SI-33-1A-196Y 143,247 l-SI-33-lA-200 142,911 1-SI-32-1-206 40,580 l-SI-32-1-214 38,140 Notes:

• See Figure 3-4

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 545,932 457,435 350,539 339,778 320,142 159,702 329,603 587,067 544,167 426,577 337,504 250,216 188,126 625,921 642,494 82,640 98,910 91,767 82,455 111,590 133,951 Total Stress (psi) 14,037 12,654 10,711 10,540 10,276 7,751 10,015 14,094 13,520 11,650 10,246 8,859 7,856 14,758 14,968 6,386 6,641 6,621. 6,461 3,231 3,498 3-8 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRJETARY CLASS 3 Table 3-6 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 Weld Location Axial Force Node (lbs) 1-SI-35-4-307 149,603 1-SI-35-4-304 150,581 1-SI-35-3RR-296 143,647 1-SI-35-3RR-294Y 143,639 1-SI-35-3RR-294Z 144,601 1-SI-35-3RR-310N 145,069 1-SI-35-3RR-3 IOF 132,993 1-SI-35-3RR-314N 132,994 1-SI-35-2R-314F 135,495 1-SI-35-2R-316N 135,287 1-SI-35-2R-316F 135,605 1-SI-35-2R-318N 135,493 1-SI-35-2R-318F 134,824 1-SI-35-2R-320N 133,895 1-SI-35-1-320F 132,895 1-SI-35-1-326N 140,594 1-SI-35-1-330F 144,765 1-SI-35-1-334 144,242 1-SI-34-1-340 42,031 1-SI-34-1-343 40,948 1-SI-34-1-344 40,949 Notes:

• See Figure 3-5

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 558,147 465,700 361,774 353,398 331,148 143,595 316,630 595,022 558,636 442,239 354,324 268,494 206,128 596,295 605,939 37,566 29,682 18,672 27,037 38,853 50,665 Total Stress (psi) 14,238 12,809 10,912 10,779 10,461 7,507 9,813 14,223 13,737 11,885 10,504 9,140 8,128 14,275 14,392 5,666 5,692 5,499 1,944 2,092 2,280 3-9 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-7 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 1 Weld Location Axial Force Node (lbs) 2-SI-56-10-416 149,651 2-SI-56-10-412 150,029 2-SI-5 6-9-406 143,099 2-SI-56-9-404Y 143,099 2-SI-56-9-404Z 144,000 2-SI-56-9-420N 144,458 2-SI-56-8-420F 133,182 2-SI-56-8-426N 133,182 2-SI-56-8-426F 136,019 2-SI-56-7-428N 135,811 2-SI-56-7-428F 136,040 2-SI-56-7-430N 135,930 2-SI-56-7-430F 135,377 2-SI-56-6-434N 134,428 2-SI-56-6-434F 133,012 2-SI-56-5-442N 140,759 2-SI-56-4-446F 144,982 2-SI-56-4-450 144,461 2-SI-56-3-456 41,893 ... SI-56-3-458F 40,084 2-SI-56-3-460 40,083 Notes:

• See Figure 3-6

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 543,376 460,335 371,247 364,094 333,400 137,677 294,094 585,298 544,178 430,650 344,620 267,996 200,323 585,021 601,203 19,495 24,925 36,168 46,418 70,391 84,642 Total Stress (psi) 14,005 12,704 11,042 10,929 10,475 7,392 9,463 14,076 13,526 11,721 10,366 9,148 8,056 14,116 14,321 5,386 5,624 5,784 2,246 2,561 2,787 3-10 January 2018 RevisionO

• • • This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-8 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 Weld Location Axial Force Node (lbs) 2-SI-57-10-361 150,058 2-SI-57-10-358 150,601 2-SI-57-9-352 143,667 .. 2-SI-57-9-350X 143,667 2-SI-57-9-350Z 137,932 2-SI-57-9-348F I37,3q9 2-SI-57-8-348N 148,713 2-SI-57-8-344F 148,713 2-SI-57-8-344N 145,886 2-SI-57-7-342F 146,134 2-SI-57-7-342N 146,088 2-SI-57-7-340F

-146,250 2-SI-57-7-340N 146,749 2-SI-57-6-338F 147,823 2-SI-57-6-338N 148,892 2-SI-57-5-332F 141,297 2-SI-57-4-332N 141,478 2-SI-57-4-326F 141,478 2-SI-57-4-326N 142,887 2-SI-57-4-324Y 136,719 2-SI-57-4-365 136,328 2-Sl-57-3-368 34,048 2-Sl-57-3-374 40,010 Notes:

• See Figure 3-7

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 545,366 455,303 352,318 342,929 330,093 146,848 307,489 583,312 543,484 429,243 340,780 226,938 172,793 608,808 618,226 88,253 86,492 99,948 111,859 132,788 103,172 115,867 86,160 Total Stress (psi) 14,052 12,645 10,763 10,614 10,204 7,281 10,235 14,604 13,871 12,071 10,668 8,870 8,030 14,976 15,164 6,495 6,473 6,686 6,926 7,035 6,552 3,064 2,808 3-11 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-9 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 Weld Location Axial Force Node (lbs) 2-SI-58-10-171 149,588 2-SI-58-10-168 150,011 2-Sl-58-9-162 143,081 2-SI-58-9-160Y 143,081 2-SI-58-9-160Z 144,042 2-SI-58-9-174N 144,604 2-SI-58-8-174F 132,871 2-S1-58-8-178N 132,871 2-S1-58-8-178F 135,786 2-SI-58-7-180N 135,537 2-SI-58-7-180F 135,723 2-S1-58-7-182N 135,592 2-S1-58-7-182F 134,989 2-S1-58-6-184N 133,878 2-S1-58-6-184F 132,765 2-S1-58-5-190N 139,574 2-S1-58-4-f94F 144,633 2-S1-58-4-196Y 143,610 2-SI-58-4-200 143,270 2-SI-58-3-206 40,939 2-Sl-58-3-212F 38,842 2-SI-58-3-214 38,842 Notes:

• See Figure 3-8

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 542,679 454,313 351,593 341,851 320,594 160,824 330,395 587,453 545,092 427,002 337,416 249,711 187,744 630,745 641,494 38,643 39,516 43,662 58,945 84,090 108,533 106,898 Total Stress (psi) 13,992 12,608-10,731 10,576 10,274 7,764 10,026 14,098 13,533 . 11,653 10,241 8,846 7,843 14,821 14,951 5,647 5,843 5,872 6,102 2,809 3,120 3,094 3-12 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-10 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 Weld Location Axial Force Node (lbs) 2-SI-59-10-307 150,095 2-SI-59-10-304 150,649 2-SI-59-9-296 143,709 2-S1-59-9-294Y 143,715 2-S1-59,.9,~294Z 144,752 2-SI-59-9-3 lON 145,176 2-SI-59-8-3 lOF 132,973 2-S1-59-8-314N 132,974 2-S1-59-8-314F 135,386 2-S1-59-7-316N 135,177 2-SI-59-7-316F 135,523 2-SI-59-7-31 SN 135,407 2-SI-59-7-3 lSF 134,713 2-S1-59-6-320N 133,784 2-S1-59-6-320F 132,870 2-S1-59-5-326N 140,587 2-S1-59-4-330F 145,954 2-SI-59-4-334 145,430 2-SI-59-3-340 42,862 2-SI-59-3-344 40,932 Notes:

• See Figure 3-9

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 554,493 462,270 357,048 348,610 338,702 138,638 312,445 596,893 561,931 445,283 357,096 271,143 208,346 597,562 605,979 40,839 33,498 25,819 14,809 35,700 Total Stress (psi) 14,198 12,757 10,840 10,706 10,587 7,433 9,746 14,252 13,785 11,930 10,545 9,179 8,160 14,292 14,392 5,718 5,795 5,655 1,781 2,042 3-13 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPR.IBTARY CLASS 3 3-14 Table 3-11 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses-for 10-inch Accumulator Injection Line Loop 1 Weld Location Axial Force Node (lbs) 1-SI-29-4-416 153,672 1-SI-29-4-412 153,946 1-SI-29-3R-406 146,721 1-SI-29-3R-404Y 146,708 1-SI-29-3R-404Z 148,186 1-SI-29-3R-420N 147,785 1-SI-29-3R-420F 150,017 1-SI-29-2-426N 149,655 1-SI-29-2-426F 147,300 1-SI-29-2-428N 147,466 1-SI-29-2-428F 148,333 1-SI-29-2-430N

' 148,854 1-SI-29-2-430F 148,404 1-SI-29-2-434N 149,155 1-SI-29-1-434F 150,250 1-SI-29-1-442N 143,611 1-SI-29-1-446F 149,385 1-SI-29-1-450 148,910 1-SI-28-1-456 46,553 1-SI-28-1-459 43,989 Notes:

• See Figure 3-2

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 942,766 781,220 541,792 511,106 469,759 211,852 359,241 665,307 650,728 585,585 485,703 253,259 265,934 664,249 654,108 203,227 157,310 210,917 312,358 325,555 Total Stress (psi) 20,477 17,928 13,875 13,388 12,786 8,687 11,102 15,937 15,621 14,595 13,,044 9,381 9,566 15,902 15,781 8,399 7,880 8,712 6,627 6,744 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-12 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 Weld Location Axial Force Moment Total Stress Node (lbs) (in-lbs) (psi) 1-SI-31-4-361 154,404

• 952,033 20,650 1-SI-31-4-358 152,740 789,100 18,009 1-SI-31-3R-352 145,511 548,357 13,935 1-SJ.:31-3R-350X 145,498 508,389 13,301 1-SI-31-3R-350Z 147,631 486,646 13,034 1-SI-31-3R-348F 147,051 240,974 9,121 1-SI-3 l-3R-348N 149,869 372,305 11,303 1-SI-31-3R-344F 149,387 638,071 15,496 l-SI-31-2-344N 147,035 610,125 14,968 1-SI-3 l-2-342F 147,236 495,600 13,162 1-SI-31-2-342N 146,912 408,000 11,762 1-SI-31-2-340F 147,103 288,840 9,882 1-SI-31-2-340N 147,764 231,000 8,989 1-SI-31-1A-338F 148,728 689,316 16,284 l-SI-31-1A-338N 149,712 673,084 16,062 l-SI-31-1A-332F 146,225 140,085 7,493 1-SI-3 l-1A-332N 147,023 154,999 7,758 1-SI-31-1A-330F 146,976 128,480 7,337 1-SI-31-lA-324 141,935 139,947 7,337 l-SI-31-1A-324Y 145,662 297,275 9,963 1-SI-31-lA-365 145,212 171,169 7,949 1-SI-30-1-369N 42,645 121,272 3,459 1-SI-30-1-372F 45,895 141,382 3,895 1-SI-30..:1-374 45,911 133,357 3,768 Notes:

• See Figure 3-3

• Axial force includes pressure Pipe Geometry and Loading

• WCAP-18295-NP 3-15 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement_was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-13 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 Weld Location Axial Force Node (lbs) 1-SI-33-4-171 154,449 ',* 1-SI-33-4-168 151,850 1-SI-33-3R-162 144,623 1-SI-33-3R-160Y 144,616 1-SI-33-3R-160Z 147,423 1-SI-33-3R-174N 146,959 1-SI-33-3R-174F 149,946 1-SI-33-3R-178N 149,575 1-SI-33-2-178F 147,267 1-SI-33-2-1 SON 147,477 1-SI-33-2-1 SOF 146,974 1-SI-33-2-182N 147,107 1-S1-33-2-182F 147,947 1-S1-33-2-184N 148,927 1-SI-33-1A-184F 149,821 1-SI-3 3-1A-190N 144,313 1-SI-33-lA-196 143,545 1-SI-33-1A-196Y 149,256 1-SI-33-lA-200 148,879 1-SI-32-1-206 46,374 1-SI-32-1-214 48,770 Notes:

• See Figure 3-4

• Axial force includes pressure Pipe Geometry and Loading . WCAP-18295-NP Moment (in-lbs) 901,426 761,463 536,440 498,873 442,778 258,020 400,054 640,568 609,999 485,807 397,219 301,798 237,093 694,425 711,587 276,976 304,639 399,444 . 255,528 222,432 239,236 Total-Stress (psi) 19,850 17,539 13,714 13,119 12,332 9,388 11,746 15,542 14,975 13,015 11,594 10,087 9,092 16,372 16,676 9,593 10,003 11,711 9,418 5,196 5,549 3-16 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-17 Table 3-14 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 Weld Location Axial Force Node (lbs) 1-SI-35-4-307 154,554 1-SI-35-4-304 152,576 I 1-SI-35-3RR-296 145,345 1-SI-35-3RR-294Y 145,332 1-SI-35-3RR-294Z 147,986 1-SI-35-3RR-310N 147,518 1-SI-35-3RR-310F 149,705 1-SI-35-3RR-314N 149,405 1-SI-35-2R-314F 147,354 1-SI-35-2R-316N 147,555 1-SI-35-2R-316F 146,931 1-SI-35-2R-318N 147,080 1-SI-35-2R-318F 148,019 1-SI-35-2R-320N 149,016 1-SI-35-1-320F 149,633 1-SI-35-1-326N 142,784 1-SI-35-1-330F 147,894 1-SI-35-1-334 147,326 1-SI-34-1-340 45,110 1-SI-34-1-343 43,528 1-SI-34-1-344 43,360 Notes:

• See Figure 3-5

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 933,994 766,603 521,590 485,618 474,798 218,605 368,180 635,330 613,318 500,811 417,057 .. 330,240 263,726 669,413 653,715 201,489 156,026 155,105 231,951 244,127 222,408 Total Stress (psi) 20,370 17,647 13,505 12,935 12,859 8,784 11,232 15,453 15,031 13,256 11,906 10,536 9,517 15,979 15,753 8,342

• 7,806 7,771 5,301 5,437 5,087 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-15 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 1 Weld Location Axial Force Node (lbs) 2-SI-56-10-416 154,850 2-SI-56-10-412 152,074 2-SI-56-9-406 144,653 2-SI-56-9-404Y 144,644 2-SI-56-9-404Z 147,675 2-SI-56-9-420N 147,200 2-SI-56-8-420F 149,883 2-SI-56-8-426N 149,401 2-SI-56-8-426F 146,934 2-SI-56-7-428N 147,130 2-SI-56-7-428F 146,62L{ 2-SI-56-7-430N 146,754 2-SI-56-7-430F 147,567 2-SI-56-6-434N 148,583 2-SI-56-6-434F 149,711 2-SI-56-5-442N 143,803 2-SI-56-4-446F 149,901 2-SI-56-4-450 149,341 2-SI-56-3-456 46,670 2-SI-56-3-458F 44,438 2-SI-56-3-460 44,252 Notes: '

• See Figure 3-6

• Axial force includes pressure Pipe Geometry and Loading WCAP~l8295-NP Moment (in-lbs) 881,028 738,135 540,790 510,587 474,565 221,137 360,838 635,776 605,903 496,465 409,344 330,436 261,721 654,713 649,740 225,713 169,423 224,348 334,073 339,098 297,910 Total Stress (psi) 19,542 17,178 13,784 13,305 12,844 8,813 11,122 15,460 14,898 13,171 11,773 10,528 9,469 15,731 15,693 8,763 8,091 8,941 6,975 6,974 6,315 3-18 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-19 Table 3-16 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 2 Weld Location Axial Force Node (lbs) 2-SI-57-I0-361 154,785 2-SI-57-10-358 152,910 2-SI-57-9-352 145,580 2-SI-57-9-350X 145,569 2-SI-57-9-350Z 147,817 2-SI-57-9-348F 147,242 2-SI-57 348N 150,193 2-S1-57-8-344F 149,631 2-S1-57-8-344N 147,232 2-S1-57-7-342F 147,461 2-SI-57-7-342N 147,082 2-SI-57-7-340F 147,290 2-SI-57-7-340N 148,059 2-S1-57-6-338F 149,189 2-S1-57-6-338N 149,941 2-SI-57-5-332F 144,134 2-S1-57-4-332N 144,113 2-S1-57-4-326F 144,098 2-SI-57-4-326N 143,623 2-S1-57-4-324Y 147,576 2-SI-57-4-365 147,983 2-SI-57-3-368 49,754 2-Sl-57-3-374 43,079 Notes:

• See Figure 3-7

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 930,327 780,228 550,743 511,768 481,026 247,668 383,617 639,502 612,808 500,072 408,334 289,277 237,803 689,628 674,341 265,896 261,199 251,473 256,107 407,080 281,549 210,309 187,522 Total Stress (psi) 20,320 17,875 13,975 13,358 12,952 9,234 11,494 15,527 15,018 13,241 11,774 9,895 9,108 16,306 16,091 9,411 9,336 9, 18-1 9,237 11,772 9,798 5,126 4,524 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-17 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 3 Weld Location Axial Force Node (lbs) 2-SI-58-10-171 155,131 2-SI-58-10-168 152,408 2-SI-58-9-162 145,111 2-SI-58-9-160Y 145,101 2-SI-58-9-160Z 147,868 2-SI-58-9-174N 147,313 2-SI-58-8-174F 150,295 2-SI-58-8-178N 149,785 2-SI-58-8-178F 147,541 2-SI-58-7-180N 147,779 2-SI-58-7-180F 147,170 2-SI-58-7-182N 147,331 2-SI-58-7-182F 148,328 2-SI-58-6~184N 149,512 2-SI-58-6-184F 150,085 2-SI-58-5-190N 144,043 2-SI-58-4-194F 156,146 2-SI-58-4-196Y 147,601 2-SI-58-4-200 147,198 2-SI-58-3-206 44,594 2-SI-58-3-212F 47,965 2-SI-58-3-214 47,974 Notes:

• See Figure 3-8

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 963,864 816,935 586,733 546,305 482,583 276,331 414,861 648,744 620,256 497,191 409,449 312,371 248,448 720,276 729,325 183,813 -220,688 338,570 202,172 160,676 208,334 196,809 Total Stress (psi) 20,864 18,438 14,529 13,888 12,978 9,691 11,993 15,679 15,147 13,206 11,794 10,262 9,286 16,803 16,967 8,107 9,128 10,687 8,512 4,154 5,030 4,848 3-20 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Table 3-18 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for 10-inch Accumulator Injection Line Loop 4 Weld Location Axial Force Node (lbs) 2-SI-59-10-307 155,202 2-SI-59-10-304 152,894 2-SI-59-9-296 145,478 2-SI-59-9-294Y 145,476 .. 2-SI-59-9-294Z 147,968 2-SI-59-9-3 lON 147,567 2-SI-59-8-3 lOF 149,838 2-SI-59-8-314N 149,475 2-SI-59-8-314F 147,647 2-SI-59-7-316N 147,848 2-SI-59-7-316F 147,148 2-SI-59-7-318N 147,299 2-SI-59-7-318F 148,309 2-SI-59-6-320N 149,290 2-SI-59-6-320F 149)97 2-S1-59-5-326N 143,537 2-S1-59-4-330F 149,661 2-Sl-59-4-334 149,098 2-SI-59-3-340 46,391 2-SI-59-3-344 44,025 Notes:

• See Figure 3-9

• Axial force includes pressure Pipe Geometry and Loading WCAP-18295-NP Moment (in-lbs) 970,257 794,224 534,370 494,266 483,080 228,424 371,593 641,406 624,363 509,412 421,203 331,829 267,901 674,205 656,912 236,480 188,469 190,010 276,428 292,096 Total Stress (psi) 20,968 18,096 13,712 13,077 12,990 8,941 11,291 ~5,552 15,216 13,402 11,980 10,570

• 9,593 16,065 15,809 8,923 8,384 8,388 6,052 6,215 3-21 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 -l~egment 111--Pi I..-Segment II -ri . Segment I ----""1 Cold Leg I I J 3-22 Accumulator Tank Figure 3-110-inch Accumulator Line Layout Showing Segments for D.C. Cook Units 1 and 2 Pipe Geometry and Loading WCAP-18295-NJ>._

January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-23 Figure 3-2 D.C. Cook Unit 1 Accumulator Line Loop 1 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRJETARY CLASS 3 3-24 Figure 3-3 D.C. Cook Unit 1 Accumulator Line Loop 2 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-25 *** Figure 3-4 D.C. Cook UnitJ Accumulator Line Loop 3 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME .system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 Loop4 Cold Leg 3-26 Figure 3-5 D.C. Cook Unit 1 Accumulator Line Loop 4 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 ~** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 RC COLO L~C L0t_1P-1 3-27 Figure 3-6 D.C. Cook Unit 2 Accumulator Line Loop 1 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation).

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-28 Figure 3-7 D.C. Cook Unit 2 Accumulator Line Loop 2 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

• WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-29 Figure 3-8 D.C. Cook Unit 2 Accumulator Line Loop 3 Layout Showing Weld Locations with Node Points Pipe Geometry and .Loading WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM.*( This statement was added by the PRIME system upon its validation) 31G *****{ r( * * * ...... RC COLD LEG \** LOOP .t WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-30 tt .... .. Figure 3-9 D.C. Cook Unit 2 Accumulator Line Loop 4 Layout Showing Weld Locations with Node Points Pipe Geometry and Loading

• WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

• WESTINGHOUSE NON-PROPRIETARY CLASS 3 4-1 4.0 MATERIAL CHARACTERIZATION

4.1 ACCUMULATOR

LINE PIPE MATERIAL AND WELD PROCESS The material type of the accumulator line for D.C. Cook Units 1 and 2 is A376 TP316 (seamless pipe) and A 403 WP316 ( wrought fittings) for the pipe and fittings, respectively.

The welding processes used are Submerged Arc Weld (SAW) and Shielded Metal Arc Weld (SMAW). In the following sections the tensile properties of the materials are presented for use in the Leak-Before-Break analyses.

4.2 TENSILE

PROPERTIES Certified Material Test Reports (CMTRs) with mechanical properties were not readily available for the D.C. Cook Units 1 and 2 accumulator lines. For the D.C. Cook Units I and 2 accumulator lines, the ASME Code mechanical properties were used to establish the tensile properties for the Leak-Before-Break analyses.

The tensile properties for the pipe material are provided in Table 4-1 for the Units I and 2 accumulator lines. For the A376 TP316 pipe material and the A403 WP316 fitting material, the representative properties at operating temperatures are established from the tensile properties interpolated from Section II of the ASME Boiler and Pressure Vessel Code (Reference 4-1 ). Code tensile properties at the operating temperatures were obtained by interpolating between various tensile Code properties.

The modulus of elasticity value was also *interpolated from ASME Code properties, and Poisson's ratio was taken as 0.3. 4.3 REFERENCE 4-1 ASME Boiler and Pressure Vessel Code,Section II, Part D, "Properties (Customary)

Materials," 2007 Edition up to and including 2008 Addenda. Table 4-1 Mechanical Properties for 10-inch Accumulator Lines Material at Operating Temperatures for D.C. Cook Units 1 and 2 Material A376 TP316 A403 WP316 A376 TP316 A403 WP316 Material <;::haracterization WCAP-18295-NP Temperature (OF) 549 120 Modulus of Yield Strength Elasticity (E) (psi) (ksi) 25,606 19,461 27,992 28,960 Ultimate Strength (psi) 71,800 75,000 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

( WESTINGHOUSE NON-PROPRIETARY CLASS 3 5-1 5.0 CRITICAL LOCATIONS

5.1 CRITICAL

LOCATIONS The Leak-Before-Break (LBB) evaluation margins are to be demonstrated for the critical locations (governing locations).

Such locations are established based on the loads (Section 3.3) and the material properties established in Section 4.2. These locations are defined below for the D.C. Cook accumulator lines. Critical Locations for the 10-inch accumulator lines (see Table 5-1): The welds in the accumulator line are fabricated using Shielded Metal Arc Weld (SMAW) and Submerged Arc Weld (SAW) for field and shop welds. The pipe material type is A376 TP 316 or A403 WP316 which have identical material properties.

The governing locations were established on the basis of the pipe geometry, material type, operating temperature, operating pressure, and the highest faulted stresses at the welds. Table 5-1 shows the highest faulted stresses and the corresponding weld location node for each welding process type in each segment of the 10-inch accumulator lines, enveloping both D.C. Cook Units 1 and 2. Definition of the piping segments and the corresponding operating pressure and temperature parameters are from Tables 3-1 and 3-2. Figures 5-1 through 5-3 show the location ofthe critical welds. Table 5-1 Summary ofD.C. Cook Unit 1 Piping Geometry and Normal Operating Condition for 10-inch Accumulator Lines and Critical Locations Segment Pipe Size I 10-inch II 10-inch III 10-inch Critical Locations WCAP-18295-NP Welding Process SMA,W SAW SMAW SAW SMAW SAW SMAW Operating Operating Maximum Pressure Temperature Faulted Stress (psig) (OF) (psi) 2,345 549 20,968 2,235 549 13,888 2,235 549 14,529 2,235 120 16,803 2,235 120 16,967 644 120 6,974 644 120 6,975 Weld Location Node 2-SI-59-10-307 2-SI-58-9-160Y 2-SI-58-9-162 2-SI-58-6-184N 2-SI-58-6-184F 2-SI-56-3-458F 2-SI-56-3-456 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

• :110 ....... "( * * * ..... RC COLD Lro \** LOOI' ,! Critical Locations WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3. Critical Location:

Segment I SMAW weld ( Figure 5-1 Layout Showing Critical Location Loop 4 Unit 2 5-2 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

Critical Location:

Segment II SAW weld Critical Location:

Segment II. SMAW/SAW weld Critical Locations WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3 Figure 5-2 Layout Showing Critical Locations Loop 3 Unit 2 5-3 January 2018 Revision 0 *** This record was final appmved,on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME syst~m upon its validation)

Critical Locations WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3 Critical Location:

Segment Ill SMAW weld Critical Location:

Segment Ill SAW weld C COLO LEC LOQP-1 Figure 5-3 Layout Showing Critical Locations Loop 1 Unit 2 5-4 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-1 6.0 LEAK RATE PREDICTIONS

6.1 INTRODUCTION

The purpose of this section is to discuss the method which is used to predict the flow through postulated through-wall cracks and present the leak rate calculation results for through-wall circumferential cracks. 6.2 GENERAL CONSIDERATIONS The flow of hot pressurized water through an opening to a lower back pressure causes flashing which can result in choking. For long channels where the ratio of the channel length, L, to hydraulic diameter, D 8 , (L/DH) is greater than [ r,c,e 6.3 CALCULATION METHOD The basic method used in the leak rate calculations is the method developed by [ ]a,c,e The flow rate through a crack was calculated in the following manner. Figure 6-1 (from Reference 6-2) was used to estimate the critical pressure, Pc, for the accumulator line enthalpy condition and an assumed flow. Once Pc was found for a given mass flow, the [ y,c,e was found from Figure 6-2 (taken from Reference 6-2). For all cases considered, [ r,c,e therefore, this method will yield the two-phase pressure drop due to momentum effects as illustrated in Figure 6-3, where P 0 is the operating pressure.

Now using the assumed flow rate, G, the frictional pressure drop can be calculated using ~Pr= [ where the friction factor f is determined using the [ was obtained from fatigue crack data on stainless steel samples. these calculations was [ t,c,e (6-1) r,c,e The crack relative roughness, E, The relative roughness value used in The frictional pressure drop using equation 6-1 is then calculated for the assumed flow rate and added to the [ r,c,e to obtain the total pressure drop from the primary system to the atmosphere.

Leak Rate Predictions WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-2 That is, for the accumulator line: Absolute Pressure -14.7 = [ tc,e (6-2) for a given assumed flow rate G. If the right-hand side of equation 6-2 does not agree with the pressure difference between the accumulator line and the atmosphere, then the procedure is repeated until equation 6-2 is satisfied to within an acceptable tolerance which in turn leads to a flow rate value for a given crack size. For the single phase cases with lower temperature, leakage rate is calculated by the following equation (Reference 6-4) with the crack opening area obtained by the method from Reference 6-3. Q = A (2g.Af>/kp

)0.s ft 3 /sec; (6-3) Where, .Af> = pressure difference between stagnation and back pressure (lb/ft2), g = acceleration of gravity (ft/sec 2), p = fluid density at atmospheric pressure (lb/ft\ k = friction loss including passage loss, inlet and outlet of the through-wall crack, A= crack opening area (ft2). 6.4 LEAK RATE CALCULATIONS Leak rate calculations were mad~ as a function of crack length at the governing locations previously identified in Section 5. L The normal operating loads of Table 3-3 through Table 3-6 (for Unit 1), and Table 3-7 through Table 3-10 (for Unit 2) were applied, in these calculations.

The crack opening areas were estimated using the method of Reference 6-3 and the leak rates were calculated using the formulation described above. The material properties of Section 4.2 (see Table 4-1) were used for these calculations.

The flaw sizes to yield a leak rate of 8 gpm were calculated at the governing locations and are given in Table 6-1 for D.C. Cook Unit 1 and Unit 2. The flaw sizes so determined are called leakage flaw sizes. The D.C. Cook Unit 1 and 2 RCS pressure boundary leak detection system meets the intent of Regulatory Guide 1.45 and meets a leak detection capability of 0.8 gpm. Thus, to satisfy the margin of 10 on the leak rate, the flaw sizes (leakage flaw sizes) are determined which yield a leak rate of 8 gpm. Leak Rate Predictions WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS .3 6-3

6.5 REFERENCES

6-1 [ rc,e 6-2 M. M, El-Wakil, "Nuclear Heat Transport, International Textbook Company," New York, N.Y, 1971. 6-3 Tada, H., "The Effects of Shell Corrections on Stress Intensity Factors and the Crack Opening Area of Circumferential and a Longitudinal Through-Crack in a Pipe," Section II-I, NUREG/CR-3464, September 1983. 6-4 Crane, D. P., "Handbook of Hydraulic Resistance Coefficient," Flow of Fluids through Valves, Fittings, 1l.Ild Pipe by the Engineering Division of Crane, 1981, Technical Paper No. 410. Table 6-1 Segment I II III Leak Rate Predictions WCAP-18295-NP Flaw Sizes Yielding a Leak Rate of 8 gpm for the D.C. Cook Unit 1 and 2 10-inch Accumulator Lines Pipe Size Welding Weld Location Process Node IO-inch SMAW 2-SI-59-10-307 SAW 2-SI-58-9-160Y SMAW 2-SI-58-9-162 IO-inch SAW 2-SI-58-6-I84N SMAW 2-SI-58-6-I84F SAW 2-SI-56-3-458F IO-inch 2-SI-56-3-456 SMAW Leakage Flaw Size (in) 2.79 3.68 3.64 3.03 3.01 9.17 9.57 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 6-4 a,c,e Figure 6-1 Analytical Predictions of Critical Flow Rates of Steam-Water Mixtures Leak Rate Predictions WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

Leak Rate Predictions WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3 LENGTHIDtAMETER RATIO Cf .. iO) Figure 6-2 [ ]3,c,e Pressure Ratio as a Function of Lill 6-5 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

---i;;t.:,.~

.. **.:-*. WESTJNGHOUSE NON-PROPRIETARY CLASS 3 a,c,e r [ Figure 6-3 Idealized Pressure Drop Profile Through a Postulated Crack Leak Rate Predictions WCAP-18295-NP 6-6 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTJNGHOUSE NON-PROPRIETARY CLASS 3 7-1 7.0 FRACTURE MECHANICS EVALUATION

7.1 GLOBAL

FAILURE MECHANISM Determination of the conditions which lead to failure in stainless steel should be done with plastic fracture methodology because of the large amount of deformation accompanying fracture.

One method for predicting the failure of ductile material is the plastic instability method, based on traditional plastic limit load concepts, but accounting for strain hardening and taking into account the presence of a flaw. The flawed pipe is predicted to fail when the remaining net section reaches a stress level at which a plastic hinge is formed. The stress level at which this occurs is termed as the flow stress. The flow stress is generally taken as the average of the yield and ultimate tensile strength *of the material at the temperature of interest.

This methodology has been shown to be applicable to ductile piping through a large number of experiments and will be used here to predict the critical flaw size in accumulator line piping. The failure criterion has been obtained by requiring equilibrium of the section containing the flaw (Figure 7-1) when loads are applied. The detailed development is provided in Appendix A for a through-wall circumferential flaw in a pipe with internal pressure, axial force, and imposed bending moments. The limit moment for such a pipe is given by: where: ]a,c,e The analytical model described above accurately accounts for the piping internal pressure as well as imposed axial force as they affect the limit moment. Good agreement was found between the analytical predictions and the experimental results (Reference 7-1 ). For application of the limit load methodology, the material, including consideration of the configuration, must have a sufficient ductility and ductile tearing resistance to sustain the limit load. Fracture Mechanics Evaluation WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation).

WESTINGHOUSE NON-PROPRIETARY CLASS 3 7-2 7.2 LOCAL FAILURE MECHANISM The local mechanism of failure is primarily dominated by_ the crack tip behavior in terms of crack-tip blunting, initiation, extension and finally cracks instability.

The local stability will be assumed if the crack does not initiate at all. It has been accepted that the initiation toughness measured in terms of J 10 from a integral resistance curve is a material parameter defining the crack initiation.

If, for a given load, the calculated I-integral value is shown to be less than the J 10 of the material, then the crack will not initiate.

Stability analysis using this approach is performed for selected location.

7.3 RESULTS

OF CRACK STABILITY EVALUATION A stability analysis based on limit load was performed.

D.C. Cook Units 1 and 2 shop and field welds utilize SMAW and SAW weld processes.

The "Z" factor for SMAW and SAW (References 7-2 and 7-3) are as follows: Z = 1.15 [1.0 + 0.013 (OD-4)] for SMAW Z = 1.30 [1.0 + 0.010 (OD-4)] for SAW where OD is the outer diameter of the pipe in inches. The Z-factors for the SMAW and SAW were calculated for the critical locations, using the pipe outer diameter (OD) of 10.75 inches. The applied faulted loads (Table 3-11 through Table 3-14 for Unit 1 and Table 3-15 through Table 3-18 for Unit 2) were increased by the Z factor. Material properties were used from Table 4-1. Table 7-1 sumniarizes the results of the stability analyses based on limit load for Unit 1 and 2. The leakage flaw sizes are also presented in the same table. Additionally, elastic-plastic fracture mechanics (EPFM) I-integral analysis for through-wall circumferential crack in a cylinder is performed for select locations using the procedure in the EPRI Fracture Mechanics Handbook (Reference 7-4). Table 7-1 shows the results of this analysis.

7.4 REFERENCES

7-1 Kanninen, M. F., et. al., "Mechanical Fracture Predictions for Sensitized Stainless Steel Piping with Circumferential Cracks," EPRI NP-192, September 1976. 7-2 Standard Review Plan; Public Comment Solicited; 3.6.3 Leak-Before-Break Evaluation Procedures; Federal RegisterNol.

52, No. 167/Friday, August 28, 1987/Notices, pp. 32626-32633.

7-3 NUREG-0800 Revision 1, March 2007, Standard Review Plan: 3.6.3 Leak-Before-Break Evaluation Procedures.

7-4 Kumar, V., German, M.D. and Shih, C. P., "An Engineering Approach for Elastic-Plastic Fracture Analysis," EPRI Report NP-1931, Project 1237-1, Electric Power Research Institute, July 1981. Fracture Mechanics Evaluation WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 7-3 Table 7-1 Stability Results for the D.C. Cook Unit 1 and 2 10-inch Accumulator Lines Based on Limit Load Welding Weld Location Segment Pipe Size Process Node I 10-inch SMAW 2-SI-59-10-307 SAW 2-SI-58-9-160Y II 10-inch SMAW

• 2-SI-58-9-162 SAW 2-SI-58-6-184N SMAW 2-SI-58-6-184F III 10-inch SAW 2-SI-56-3-458F SMAW 2-SI-56-3-456 Note: 1. Calculated based on the methodology in Section 7.2 Fracture Mechanics Evaluation WCAP-18295-NP Critical Flaw Size (in) 10.04 11.88 12.32 11.66 12.30 18.34 1 19.14 1 Leakage Flaw Size (in) 2.79 3.68 3.64 3.03 3.01 9.17 9.57 January 2018 Revision 0. *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation) i Fracture Mechanics Evaluation*

WCAP-18295-NP WESTINGHOUSE NON-PROPRIETARY CLASS 3 Neutral Axis Figure 7-1 [ r,c.e Stress Distribution 7-4 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM_. ( This statement was added by the PRIME system upon its. validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 8-1 8.0 ASSESSMENT OF FATIGUE CRACK GROWTH The fatigue crack growth (FCG) analysis is not a requirement for the LBB analysis (see References 8-1 and 8-2) since the LBB analysis is based on the postulation of a through-wall flaw, whereas the FCG analysis is performed based. on the surface flaw. In addition Reference 8-3 has indicated that, "the Commission deleted the fatigue crack growth analysis in the proposed rule. This requirement was found to be unnecessary because it was bounded by the crack stability-analysis." Also, since the growth of a flaw which leaks 8 gpm would be expected to be minimal between the time that leakage reaches 8 gpm and the time that the plant would be shutdown; therefore, only a limited number of cycles would be expected to occur.

8.1 REFERENCES

8-1 Standard Review Plan; Public Comment Solicited; 3.6.3 Leak-Before-Break Evaluation Procedures; Federal Register/Vol.

52, No. 167/Friday, August 28, 1987/Notices, pp. 32626-32633.

8-2 NUREG-0800 Revision 1, March 2007, Standard Review Plan: 3.6.3 ... Leak-Before-Break Evaluation Procedures.

8-3 Nuclear Regulatory Commission, 10 CPR 50, Modification of General Design Criteria 4 Requirements for Protection Against Dynamic Effects of Postulated Pipe Ruptures, Final Rule, Federal Register/Vol.

52, No. 207/Tuesday, October 27, 1987/Rules and Regulations, pp. 41288-41295.

Assessment of Fatigue Crack Growth WCAP-18295-NP January 2018 Revision 0 *** This record was final approved on *1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 9-1 9.0 ASSESSMENT OF MARGINS The results of the leak rates of Section 6.4 and the corresponding stability evaluations of Section 7.3 are used in performing the assessment of margins. Margins are shown in Table 9-1 for Unit 1 and 2. All the LBB recommended margins are satisfied.

In summary, margins at the critical locations relative to: 1. Flaw Size -Using faulted loads obtained by the absolute sum method, a margin of 2 or more exists between the critical flaw and the flaw having a leak rate of 8 gpm (the leakage flaw). 2. Leak Rate -A margin of 10 exists between the calculated leak rate from the leakage flaw and the plant leak detection capability of 0.8 gpm. 3. Loads -At the critical locations the leakage flaw was shown to be stable using the faulted loads obtained by the absolute sum method (i.e., a flaw twice the leakage flaw size is shown to be stable; hence the leakage flaw size is stable). A margin of I on loads using the absolute summation of faulted load combinations is satisfied.

Table 9-1 Leakage Flaw Sizes, Critical Flaw Sizes and Margins for D.C. Cook Units 1 and 2 10-inch Accumulator Lines Welding Weld Location Critical Segment Pipe Size Flaw Size Process Node (in) ACC-I IO-inch SMAW 2-SI-59-10-307 10.04 SAW 2-SI-58-9-160Y 11.88 ACC-II 10-inch SMAW 2-SI-58-9-162 12.32 SAW 2-SI-58-6-I84N 11.66 SMAW 2-SI-58-6-184F 12.30 ACC-III IO-inch SAW 2-SI-56-3-458F 18.34 SMAW 2-SI-56-3-456 19.14 Notes: 1. Margin of2.0 demonstrated based on the methodology in Section 7.2 Assessment of Margins WCAP-18295-NP Leakage Flaw Size (in) 2.79 3.68 3.64 3.03 3.01 9.17 9.57 Margin 3.6 3.2 3.4 3.8 4.1 >2.0 1 >2.0 1 January 2018 Revision 0 *** This record was fin~~~~roved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 10-1

10.0 CONCLUSION

S This report justifies the elimination of accumulator lines break from the structural design basis for D.C. Cook Units 1 and 2 as follows: a. Stress corrosion cracking is precluded by use of fracture resistant materials in the piping system and controls on reactor coolant chemistry, temperature, pressure, and flow during normal operation.

Note: Alloy 82/182 welds do not exist at the D.C. Cook Units 1 and 2 accumulator lines. b. Water hammer should not occur in the accumulator line piping because of system design, testing, and operational considerations.

c. The effects of low and high cycle fatigue on the integrity of the accumulator line piping are negligible.

d. Ample margin exists between the leak rate of small stable flaws and the capability of the D.C. Cook Units 1 and 2 reactor coolant system pressure boundary leakage detection systems. e. Ample margin exists between the small stable flaw sizes of item ( d) and larger stable flaws. f. Ample margin exists in the material properties used to demonstrate end-of-service life (fully aged) stability of the critical flaws. i For the critical locations, flaws are identified that will be stable because of the ample margins described in d, e, and f above. Based on loading, pipe geometry, welding process, and material properties considerations, enveloping critical (governing) locations were determined at which Leak-Before-Break crack stability evaluations were made. Through-wall flaw sizes were postulated which would cause a leak at a rate often (10) times the leakage detection

~ystem capability of the plant. Large margins for such flaw sizes were demonstrated against flaw instability.

Finally, fatigue crack growth assessment was shown not to be an issue for the accumulator line piping. Therefore, the Leak-Before-Break conditions and margins are satisfied for D.C. Cook Units 1 and 2 accumulator line piping. It is demonstrated that the dynamic effects of the pipe rupture resulting from postulated breaks in the accumulator line piping need not be considered in the structural design basis of D.C. Cook Units 1 and 2. Conclusions WCAP-18295-NP January 2018 Revision 0 *** This record was final approved .on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

Appendix A: Limit Moment WCAP-18295-NP WESTJNGHOUSE NON-PROPRIETARY CLASS 3 APPENDIX A: LIMIT MOMENT ] a,c,e A-1 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 ,a) 0..----------------------~---

f.TJ Figure A-1 Pipe with a Through-Wall Crack in Bending Appendix A: Limit Moment WCAP-18295-NP A-2 January 2018 Revision 0 *** This record was final approved on 1/18/2018 9:40:03 AM. ( This statement was added by the PRIME system upon its validation)

WCAP-18295-NP Revision 0 Proprietary Class 3 **This page was added to the quality record by the PRIME system upon its validation and shall not be considered in the page numbering of this document.**

Author Approval Kirby Christopher R Jan-16-2018 14:21 :34 Reviewer Approval Johnson Eric D Jan-17-2018 14:51:15 Manager Approval Leber Benjamin A Jan-18-2018 09:40:03 Files approved on Jan-18-2018

~** This record was final approved on 1/18/2018 9:40,03 AM. ( This statement was added by the PRIME-system upon its validation)