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WCAP-18309-NP, Revision 0, Technical Justification for Eliminating Safety Injection Line Rupture as the Structural Design Basis Using Leak-Before-Break Methodology.
	ML18072A015
Person / Time
Site:	Cook
Issue date:	01/31/2018
From:	Johnson E; Westinghouse
To:	; Office of Nuclear Reactor Regulation
References
	AEP-NRC-2018-02 WCAP-18309-NP, Rev 0
	Download: ML18072A015 (74)
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ENCLOSURE 9 TO AEP-NRC-2018-02 WCAP-18309-NP, Revision O 'Technical Justification for Eliminating Safety Injection Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using Leak-Before-Break Methodology" (Non-Proprietary)

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-18309-NP January 2018 Revision 0 Technical Justification for Eliminating Safety Injection Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using Leak-Before-Break Methodology

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@ Westin .... .. g. *house *....

- - This record was final approved on 1/18/2018 9:38:47 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 WCAP-18309-NP Revision 0 Technical Justification for Eliminating Safety Injection Line Rupture as the Structural Design Basis for D.C. Cook Units 1 and 2, Using Leak-Before-Break Methodology January 2018 Author: Eric D. Johnson*

Structural Design and Analysis - II Reviewer: Momo Wiratmo*

Structural Design and Analysis - II Approved: Benjamin A. Leber, Manager*

Structura_l Design a1:1d 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

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 lll TABLE OF CONTENTS 1.0 Introduction ........................................................................................................................................ 1-1 1.1 Purpose ................................................................................................................................. 1-1 1.2 Scope and Objectives ............................................................................................................ 1-1 1.3 References ............................................................................................................................. 1-2 2.0 Operation and Stability of the Reactor Coolant System .................................................................... 2-1 2.1 Stress Corrosion Cracking ................................ ,................................................................... 2-1 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 SI lines .................................................. 2-3 2.5 References ............................................................................................................................. 2-3 3.0 Pipe Geometry and Loading .............................................................................................................. 3-1 3 .1

Calculations of Loads and Stresses .... ~ ....... :................ :................ :................ :....................... 3-1 3.2 Loads for Leak Rate Evaluation ........................................................................................... 3-1 3.3 Load Combination for Crack Stability Analyses ... ,.............................................................. 3-2 3.4 References ............................................................................................................................. 3-3 4.0 Material Characterization ................................................................................................................... 4-1 4.1 SI line Pipe Material and Weld Process ................................................................................ 4-1 4.2 Tensile Properties .................................................................................................................. 4-1 4.3 Reference .............................................................................................................................. 4-1 5.0 Critical .Locations .......... , ....... ,........ , ....... ,........, ....... ,........, ....... ,................. ,................. ,................. ,....... 5-1 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 Glob al 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 .. :................................................................................................................................... 10-1 Appendix A: Limit Moment ....................................................................................................... , .................. A-1 WCAP-18309-NP January 2018 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 iv LIST OF TABLES Table 3-1 Summary of D.C. Cook Units 1 Piping Geometry and Normal Operating Condition for the Hot Leg and Cold Leg Safety Injection Lines ........................._.................................. 3-4 Table 3-2 Summary ofD.C. Cook Units 2 Piping Geometry and Normal Operating Condition for the Hot Leg and Cold Leg Safety Injection Lines .......... ;................................................ 3-5 Table 3-3 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 1 Cold Leg ............................................................................................................................... 3-6 Table 3-4 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 2 Cold Leg ............................................................................................................................... 3-6 Table 3-5 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 3 Cold Leg ... .-........ ;....... .- ........ ;....... ;....... .-........ ;........-........ ;....... .-........ ;................ ;................ ;.... 3-7 Table 3-6 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 4 Cold Leg ............................................................................................................................... 3-7 Table 3-7 Summary of D.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 1 Hot Leg ................................................................................................................................. 3-8 Table 3-8 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 2 Hot Leg ................................................................................................................................. 3-9 Table 3-9 Sum~ary o_fD.C. Cook Un_it 1 Normal Loads an_d Stresses [or SI Line to Loop 3_ .

Hot Leg ............................................................................................................................... 3-10 Table 3-10 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 4 Hot Leg ............................................................................................................................... 3-11 Table 3-11 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 1 Cold Leg ............................................................................................................................. 3-12 Table 3-12 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 2 Cold Leg ............................................................................................................................. 3-12 Table 3-13 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 3 Cold Leg ............................................................................................................................. 3-13 Table 3-14 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 4 Cold Leg ............................................................................................................................. 3-13 Table 3-15 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 1 HotLeg ............................................................................................................................... 3-14 Table 3-16 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 2 Hot Leg ............................................................................................................................... 3-15 Table 3-17 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 3 Hot Leg ............................................................................................................................... 3-16 WCAP-18309-NP January 2018 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 V Table 3-18 Summary ofD.C. Cook Unit 2 Normal Loads and Stresses for SI Line to Loop 4 HotLeg ............................................................................................................................... 3-17 Table 3-19 Summary of D.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 1 Cold Leg ............................................................................................................................. 3-18 Table 3-20 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 2 Cold Leg ............................................................................................................................. 3-18 Table 3-21 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 3 Cold Leg ............................................................................................................................. 3-19 Table 3-22 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 4 Cold Leg ............................................................................................................................. 3-19 Table 3-23 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 1 Hot Leg ............................................................................................................................... 3-20 Table 3-24 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 2 Hot Leg ............................................................................................................................... 3-21 Table 3-25 Summary ofD.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 3 Hot Leg *****************************:*************************************************************************************************3-22 Table 3-26 Summary of,D.C. Cook Unit 1 Faulted Loads and Stresses for SI Line to Loop 4 Hot Leg ............................................................................................................................... 3-23 Table 3-27 Summary ofD.C.*Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 1 Cold Leg ............................................................................................................................. 3-24 Table 3-28 Summary of D.C. Cook Unit 2 Faulted _Loads and Stresses for SI Line to Loop 2 Cold Leg ............................................................................................................................. 3-24 Table 3-29 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 3 Cold Leg ............................................................................................................................. 3-25 Table 3-30 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 4 Cold Leg ............................................................................................................................. 3-25 Table 3-31 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 1 Hot Leg ............................................................................................................................... 3-26 Table 3-32 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 2 Hot Leg ............................................................................................................................... 3-27 Table 3-33 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 3 Hot Leg ............................................................................................................................... 3-28 Table 3-34 Summary ofD.C. Cook Unit 2 Faulted Loads and Stresses for SI Line to Loop 4 Hot Leg ............................................................................................................................... 3-29 Table 4-1 Material Properties for Operating Temperature Conditions on D.C. Cook Units 1 and 2 SI Lines ....................................................................................................................... 4-2 WCAP-18309-NP January 2018 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 vi Table 5-1 Critical Analysis Location for Leak-Before-Break ofD.C. Cook Units 1 and 2 SI Lines ................................................................................................................................. 5-2 Table 6-1 Flaw Sizes Yielding a Leak Rate of 8 gpm for the D.C. Cook Units 1 and 2 SI lines .......... 6-4 Table 7-1 Flaw Stability Results for the D.C. Cook Units 1 and 2 SI Lines Based on Limit Load and EPFM .................................................................................................................... 7-3 Table 9-1 Leakage Flaw Sizes, Critical Flaw Sizes, and Margin for the D.C. Cook Units 1 and 2 SI Lines ....................................................................................................................... 9-2 WCAP-18309-NP January 2018 Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 vu LIST OF FIGURES Figure 3-1 D.C. Cook Units 1 and 2 Typical Piping Layout for SI lines .............................................. 3-30 Figure 3-2 D.C. Cook Unit 1 Cold Leg SI Line Layout Showing Weld Locations with Node Points - Loops 1 through 4 ................................................................................................. 3-31 Figure 3-3 D.C. Cook Unit 1 Hot Leg SI Line Layout Showing Weld Locations with Node Points -Loops 1 and 4 ........................................................................................................ 3-32 Figure 3-4 D.C. Cook Unit 1 Hot Leg SI Line Layout Showing Weld Locations with Node Points - Loops 2 and 3 .. :..................................................................................................... 3-33 Figure 3-5 D.C. Cook Unit 2 Cold Leg SI Line Layout Showing Weld Locations with Node Points - Loops 1 through 4 ................................................................................................. 3-34 Figure 3-6 D.C. Cook Unit 2 Hot Leg SI Line Layout Showing Weld Locations with Node Points - Loops 1 and 4 ........................................................................................................ 3-35 Figure 3-7 D.C. Cook Unit 2 Hot Leg SI Line Layout Showing Weld Locations with Node Points-Loops 2 and 3 ........................................................................................................ 3-36 Figure 5-1 D.C. Cook Unit 2 Cold Leg SI Line Critical Weld Locations .............................................. 5-3 Figure 5-2 D.C. Cook Unit 1 Hot Leg SI Line Loops 1 and 4 Critical Weld Locations ......................... 5-4 Figure 5-3 D.C. Cook Unit 2 Hot Leg SI Line Loop 1 Critical Weld Locations .................................... 5-4 Figure 5-4 D.C. Cook Unit 2 Hot Leg SI Line Loop 3 Critical Weld Locations .................................... 5-5 Figure 6-1 Analytical Predictions of Critical Flow Rates of Steam-Water Mixtures ............................. 6-5 Figure 6-2 t,c,e Pressure Ratio as a Function of LID ............................................ 6-6 Figure 6-3 Idealized Pressure Drop Profile Through a Postulated Crack ............................................... 6-7 Figure 7-1 [ r,c,e Stress Distribution .................................................................................. 7-4 _

FigureA-1 Pipe with a Through-Wall Crack in Bending ....................................................................... A-2 WCAP-18309-NP January 2018 Revision 0

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r 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 Safety Injection (SI) lines, including the 6-inch and 8-inch lines directly attached to the hot leg piping of the reactor coolant system (RCS) as well as the IO-inch and 6-inch lines attached to the accumulator line piping for injection into the cold leg of the RCS, 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 SI 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 SI 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 SI lines from the hot leg piping of each loop of the RCS through a check valve and up to an isolation valve, as well as the SI lines from the IO-inch Accumulator lines up to the first check valve.

Schematic drawing of the piping systems are shown in Section 3.0, Figure 3-1. 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 c_an be_ brie:!Jy summar_ized as follows:_

1. 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 material types used in the plant, provide representative material properties.

7. Demonstrate margin on applied load by combining the faulted loads by absolute summation method.

Introduction January 2018 WCAP-18309-NP Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 1-2 This report provides a fracture mechanics demonstration of SI 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).

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

Introduction January 2018 WCAP-18309-NP Revision 0

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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 (RCS) 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) fanned 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 enviromnent. 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 January 2018 WCAP-18309-NP Revision 0

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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 of I GSCC have been reported for PWR primary coolant systems.

Primary Water Stress Corrosion Cracking (PWSCC) occurred in the V. C. Summer reactor vessel hot leg nozzle, Alloy 82/182 weld. It should be noted that this susceptible material is not found at the D.C. Cook Units 1 and 2 SI lines.

2.2 WATER HAMMER.

Overall, there is a low potential for water hammer in the RCS and connecting SI lines since they are designed and operated to preclude the voiding condition in normally filled lines. The RCS and connecting SI 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 also controlled 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 Jines. Preoperational testing and operating experience has verified the Westinghouse approach. The operating transients of the RCS primary piping and connected SI 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.1 Code does not contain an explicit piping low cycle fatigue analysis requirement. The B31.1 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 January 2018 WCAP-18309-NP Revision 0

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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 RCP have been found analytically to be very small, between 2 and 3 ksi at the highest. Field measurements on a typical PWR plant indicate vibration stress amplitudes less than 1 ksi. When translated to the connecting SI lines, these stresses would be even lower, well below the fatigue endurance limit for the SI 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 SI LINES The SI lines and the associated fittings for the 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 SI piping is about 618°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 SI lines.

Wall thinning by erosion and erosion-corrosion effects should not occur in the SI piping due to the low

. velo_city, typic~lly less than 1._0 ft/sec and the stainless steel material, which_ is hi_ghly _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 SI lines. The cause of wall thinning is related to high water velocity and is therefore clearly not a mechanism that would affect the SI piping.

Brittle fracture for stainless steel material occurs when the operating temperature is about -200°F. SI line operating temperature is higher than 120°F and therefore, brittle fracture is not a concern for the SI lines.

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 January 2018 WCAP-18309-NP Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-1 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:

F M (3-1) cr =-+

A Z

where, cr stress, psi F axial load, lbs M moment, in-lbs A pipe cross-sectional area, in2 Z section modulus, in3 The moments for the desired loading combinations are calculated by the following equation:

2 2 2 M =~M X +M y +M Z (3-2)

where, Mx X component of moment, Torsion My Y component of bending moment M2 Z component of bending moment 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 FDw + Frn + Pp (3-3)

Mx = (Mx)Dw + (Mx)rn (3-4)

Mv (Mv)Dw + (Mv)rn (3-5)

Mz = (Mz)Dw + (Mz)rn (3-6)

Pipe Geometry and Loading January 2018 WCAP-18309-NP Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-2 The subscripts of the above equations represent the following loading cases:

DW = dead weight 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 through 3-18 at all the weld locations.

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 ...J2 to 1.0. The absolute summation of loads is shown in the following equations:

F .= I FDW

. I+ . I FTH I + IF.p I + IFSSE!NERTIA. I + IF. SSEAM I (3-7)

Mx = I (Mx)nw I + I (Mx)rn I + I (Mx)ssEINERnAI + I (Mx)ssEAMI (3-8)

My= I (My)nw I+ I (My)rn I+ I (My)ssEINERTIAI + I (My)ssEAMI (3-9)

Mz = I CMz)nw I + I(Mz)rn I+ I (Mz)ssEINERTIAJ + I (Mz)ssEAMJ (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 used 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 3-19 and 3-34.

Notes: For the cold leg SI lines, LBB analysis will not be performed at the locations beyond the first check valve. The cold leg SI line check valve, in conjunction with the 10-inch check valve on the Accumulator line, provides protection against break propagation. Any break beyond the second check valve will not have any effect on the primary loop piping system. Similar justification is considered for the hot leg SI lines, in that LBB analysis will not be performed at the locations beyond the isolation valve.

The check valve and isolation valve, in series on the hot leg SI lines, provides protection against break propagation. Any break beyond the isolation valve will not have any effect on the primary loop piping Pipe Geometry and Loading January 2018 WCAP-18309-NP Revision 0

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WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-3 system. Figure 3-1 illustrates the typical layout of the cold leg and hot leg SI lines, 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 Register/Vol. 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 January 2018 WCAP-18309-NP Revision 0

- - This record was final approved on 1/18/2018 9:38:47 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 the Hot Leg and Cold Leg Safety Injection Lines Minimum Normal Operating Outer Weld Location Wall Loop Segment Diameter Temperature Pressure Nodes Thickness (in) (OF) (psig)

(in) 403F to 402 10.750 0.896 SI-CL-I 120 2,235 398 6.625 0.650 1 SI-HL-I 181 to 174 6.625 0.650 618 2,235 SI-HL-II 170F to 152B 6.625 0.650 120 2,235 SI-HL-III 148X to 132 . 8.625 0.731 . 120* 2,235 400Nto 400F 10.750 0.896 SI-CL-I 120 2,235 406 6.625 0.650 2 SI-HL-I 511 to SOOP 6.625 0.650 618 2,235 SI-HL-II SOOP to 479 6.625 0.650 120 2,235 SI-HL-III 96X to 78 8.625 0.731 120 2,235 158F to 158N 10.750 .0.896 SI-CL-I 120 2,235 152 6.625 0.650 3 SI-HL-I 550 to 536F 6.625 0.650 618 2,235 SI-HL-II 536F to 516 6.625 0.650 120 2,235 SI-HL-III 96Yto 78 8.625 0.731 120 2,235 294X 10.750 0.896 SI-CL-I 120 2,235 290 to 284 6.625 0.650 4 SI-HL-I 221 to 214 6.625 0.650 618 2,235 SI-HL-II 2IOF to 190 6.625 0.650 120 2,235 SI-HL-III 148Y to 132 8.625 0.731 120 2,235 Notes:

Figure 3-1 shows the piping layout and segments.

Figures 3-2 through 3-7 show the weld locations for each line analyzed.

Material type is A376 TP316 or A403 WP316.

Piping in segment SI-CL-I is IO-inch Schedule 140 and 6-inch Schedule 160.

Piping in segment SI-HL-I and SI-HL-II is 6-inch Schedule 160.

Piping in segment SI-HL-III is 8-inch Schedule 140 .

. The minimum wall thickness is conservatively based at the weld counterbore and not per ASME Code requirement.

Pipe Geometry and Loading January 2018 WCAP-18309-NP Revision 0

- - This record was final approved on 1/18/2018 9:38:47 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 the Hot Leg and Cold Leg Safety Injection Lines Minimum Normal Operating Outer Weld Location Wall Loop Segment Diameter Temperature Pressure Nodes Thickness (in) {°F) (psig)

(in) 402F to 402N 10.750 0.896 SI-CL-I 120 2,235 400 to 388 6.625 0.650 1 SI-HL-I 181 to 174 6.625 0.650 618 2,235 SI-HL-11 170F to 150 6.625 0.650 120 2,235 SI-HL-III . 148X to 132 8.625 0.731 120 2;235 .

400N to 400F 10.750 0.896 SI-CL-I 120 2,235 404 to 412 6.625 0.650 2 SI-HL-I 511 to 500F 6.625 0.650 618 2,235 SI-HL-11 500F to 479 6.625 0.650 120 2,235 SI-HL-III 96X to 78 8.625 0.731 120 2,235 158F to l58N .10.750 0.896 SI-CL-I 120 2,235 156 to 146 6.625 0.650 3 SI-HL-I 550 to 536F 6.625 0.650 618 2,235 SI-HL-11 536F to 516 6.625 0.650 120 2,235 SI-HL-III 96Yto 78 8.625 0.731 120 2,235 294X 10.750 0.896 SI-CL-I 120 2,235 288F to 284 6.625 0.650 4 SI-HL-I 221 to 214 6.625 0.650 618 2,235 SI-HL-11 210F to 188 6.625 0.650 120 2,235 SI-HL-III 148Yto 132 8.625 0.731 120 2,235 Notes:

Figure 3-1 shows the piping layout and segments.

Figures 3-2 through 3-7 show the weld locations for each line analyzed.

Material type is A376 TP316 or A403 WP316.

Piping in segment SI-CL-I is 10-inch Schedule 140 and 6-inch Schedule 160.

Piping in segment SI-HL-I and SI-HL-11 is 6-inch Schedule 160.

Piping in segment SI-HL-III is 8-inch Schedule 140.

The minimum wall thickness is conservatively based at the weld counterbore and not per ASME Code requirement.

Pipe Geometry and Loading January 2018 WCAP-18309-NP Revision 0

- - This record was final approved on 1/18/2018 9:38:47 AM. ( This statement was added by the PRIME system upon its validation)

WESTINGHOUSE NON-PROPRIETARY CLASS 3 3-6 Table 3-3 Summary ofD.C. Cook Unit 1 Normal Loads and Stresses for SI Line to Loop 1 Cold Leg Weld Location Axial Force Moment Total Stress Node (lbf) (in-lbf) (psi) 403F 141,396 52,841 5,937 402 141,558 41,557 5,764 398 49,122 39,885 6,427 Notes: See Figure 3-2 for piping layout.