ML15160A612
| ML15160A612 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 06/08/2015 |
| From: | Hiremagalur J, Wong W Structural Integrity Associates |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML15160A620 | List: |
| References | |
| RS-15-158, TAC MF5654, TAC MF5655 1400187.301, Rev. 1 | |
| Download: ML15160A612 (23) | |
Text
ATTACHMENT 4 Structural Integrity Associates, Inc. Report File No. 1400187.301, Revision 1 Finite Element Model Development and Thermal Mechanical Stress Analyses for the Unit 2 N1 Nozzle (Non-Proprietary) 22 pages follow
StructuralIntegrity Associates, Inc0 File No.: 1400187.301 Project No.: 1400187 CALCULATION PACKAGE Quality Program: Z Nuclear E] Commercial PROJECT NAME:
LaSalle N702 Relief Request for 60 Years CONTRACT NO.:
00517760, Rev 4 CLIENT: PLANT:
Exelon Generation Company LLC LaSalle County Generating Station, Units I and 2 CALCULATION TITLE:
Finite Element Model Development and Thermal Mechanical Stress Analyses for the Unit 2 NI Nozzle NOTE: This document contains vendorproprietar, information. Such information has been redactedfor public release of this document.
Document Affected Project Manager Preparer(s) &
Revision Pages Revision Description Approval Checker(s)
Signature & Date Signatures & Date Preparer:
01 - 20 Initial Issue Wilson Wong A-i - A-2 Rich Bax 8/8/14 8/8/14 Checker:
Jagannath Hiremagalur 8/8/14 1 1 -20 Revised Proprietary Preparer:
A-I- A-2 Markings %K Rich Bax Wilson Wong 2/6/15 2/6/15 Checker:
Jagannath Hiremagalur 2/6/15 Page 1 of 20 F0306-01R I
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Table of Contents 1.0 OBJECTIVE ............................................................................................................ 4 2.0 A SSU M PTION S ........................................................................................................ 4 3.0 D ESIGN IN PUTS ..................................................................................................... 4 3.1 N ozzle Geom etry ......................................................................................... 4 3.2 Material Properties ....................................................................................... 5 3.3 Therm al Transient D efinitions ....................................................................... 5 4.0 FIN ITE ELEM EN T M O DEL .................................................................................. 5 5.0 STRESS AN A LY SIS ................................................................................................ 6 5.1 Unit Internal Pressure .................................................................................. 6 5.2 Therm al Transient A nalyses ........................................................................ 6 5.2.1 Thermal Analyses .......................................................................................... 6 5.2.2 Thermal Stress Analyses ................................................................................ 7 6.0 RESULTS ............................................................................................................. 7 6.1 Overall Stress and Tem perature Results ...................................................... 7 6.2 Through-W all Stress Extractions .................................................................. 7 7.0 CON CLU SION ........................................................................................................ 7 8.0 REFEREN CES ......................................................................................................... 8 A PPEND IX A COM PU TER FILEN A M ES ................................................................... A -1 File No.: 1400187.301 Page 2 of 20 Revision: 1 F0306-01RI R
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List of Tables Table 1: Bounding Transients for Analysis ........................................................................ 9 Table 2: Material Properties for Low Alloy Steel SA-508 Class 2 / SA-533 Grade B, C lass t .................................................................................................................... 10 Table 3: Material Properties for Stainless 308L (Treated as Type 304) .................................. 11 List of Figures Figure 1: Components Included in the Finite Element Model ......................................... 12 Figure 2: 3-D Finite Element Model Mesh for Analyses ................................................... 13 Figure 3: Applied Boundary Conditions and Unit Internal Pressure ................................ 14 Figure 4: Applied Thermal Boundary Conditions for Thermal Transient Analyses ...... 15 Figure 5: Applied Mechanical Boundary Conditions for Thermal Stress Analyses ...... 16 Figure 6: Total Stress Intensity Plot for Unit Internal Pressure .......................................... 17 Figure 7: Temperature Contour for Turbine Generator Trip SCRAM at Time=4602.2 sec .......................................................................................................................... 18 Figure 8: Stress Intensity Plot for Turbine Generator Trip SCRAM at Time=4602.2 sec .......................................................................................................................... 19 Figure 9: Path Locations for Through-Wall Stress Extractions ........................................ 20 File No.: 1400187.301 Page 3 of 20 Revision: I F0306-01R IR
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1.0 OBJECTIVE The LaSalle County Generating Station intends to apply the methods of Code Case N-702 [1] using guidance from BWRVIP- 108 [2] and BWRVIP-241 [3] to extend their existing inspection relief request for multiple RPV nozzles, specifically the N1, N2, N3, N5, N6, N7, N8, N9, N16, and N18 nozzles.
=[3], a bounding approach will be used to qualify all of the indicated nozzles by analyzing the Unit 2 NI nozzle with the highest fluence level from all the nozzles for both units.
The objective of this calculation is to develop a Finite Element (FE) model for the LaSalle Unit 2 NI Recirculation Outlet nozzle, and to determine the stresses caused by thermal transients and internal pressure. Nozzle piping loads are not considered since they have insignificant effects on the thick nozzle-to-vessel weld and nozzle blend radius sections. Through wall stresses at locations of interest are extracted and stored in computer files to be used in a separate Probabilistic Fracture Mechanics (PFM) calculation.
2.0 ASSUMPTIONS The following assumptions are made in this evaluation:
- The NI nozzle-to-safe end weld was not specifically modeled. Instead the material instantaneously transitions from the nozzle material to the safe end material. Since the location of stress extraction is at the nozzle-to-vessel weld and nozzle blend radius, the impact of this assumption is minimal.
" All thermal transients are assumed to start from a steady state uniform temperature.
- The stress free reference temperature for the thermal stress calculation is assumed to be 70'F.
- The nozzle is subjected to a conservative high convective heat transfer coefficient (HTC) of 10,000 Btu/hr-ft2-OF, while the entirety of the outside surface is assumed to be perfectly insulated with no heat transfer to produce a conservative temperature differential through the nozzle body.
" The cladding is assumed to be austenitic stainless steel Type 308L (evaluated as Type 304) based on previous experience.
- The nozzle-to-vessel weld is assumed to have material properties similar to the vessel and nozzle.
3.0 DESIGN INPUTS 3.1 Nozzle Geometry The reactor pressure vessel inside radius (IR) is 126.5 inches to the clad surface based Reference 4, with a vessel wall thickness of 6.75 inches (includes 0.1875 inch thick cladding). The NI nozzle has an IR of 10.84375" (includes 0.1875 inch thick cladding), with an outside radius (OR) of 20.03" on the vessel side and 12.375 on the safe end side of the nozzle [4].
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3.2 Material Properties The material component identification for the nozzle of interest is obtained from References 5 and 6.
The materials used for the modeled components and their elastic properties are listed in Table 2 and Table 3. The material properties used are in conformance with the 1968 Edition (through Winter 1969 Addenda) of the ASME Boiler and Pressure Vessel Code,Section III [7]. However, since thermal conductivity and specific heat values are not listed in the 1968 Edition, these values were obtained from the 2010 ASME Boiler and Pressure Vessel Code,Section II, Part D [8].
3.3 Thermal Transient Definitions The thermal transient definitions are obtained from Reference 9. The thermal cycle diagram for the NI nozzle, Reference 9a, states that all normal and upset transients are identical to the transients specified for Region B of the Reactor Vessel. References 9b and 9c are the thermal cycle diagrams for the reactor vessel, and they are identical. The bounding transients are chosen based on their temperature range and rate of change.
There are two bounding thermal transients analyzed, and they are both tabulated in Table 1. Pressures are not included because they are determined in a separate pressure analysis described in Section 5.1.
The stresses determined in the unit pressure analysis will be scaled to the bounding transient pressure and used in a subsequent PFM evaluation.
The Loss of Feedwater Pumps transient produces the greatest temperature rate of change out of all normal and upset transients. There are three internal cycles within the main transient, the last of which occurs after an indefinite time and can be bounded by the TGT-SCRAM transient which has the same rate of change but larger temperature range. Therefore, only the first two internal cycles are considered for the Loss of Feedwater Pump/Isolation Valves Close transient.
In order to achieve a final steady state condition, an arbitrary time of 3,600 seconds was allocated after the last load step, followed by an imposed steady state load step (at an arbitrary 60 seconds after the 3,600 seconds of additional time).
4.0 FINITE ELEMENT MODEL A three-dimensional (3-D) finite element model is constructed using the ANSYS finite element program [10]. The model will be used for pressure and thermal transient stress analyses. It is developed as a symmetric quarter model using the dimensions given in Reference 4, and includes a local portion of the reactor pressure vessel, the N I nozzle-to-vessel weld, the N I nozzle, and a portion of the attached safe end, as shown in Figure 1. The N 1 nozzle-to-safe end weld was not modeled because it is not near the region of interest and is assumed to have minimal effect. The model is meshed with the SOLID45 element type from the ANSYS library of elements, for which the thermal equivalent is SOLID70. The mesh used in this calculation is depicted in Figure 2.
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5.0 STRESS ANALYSIS 5.1 Unit Internal Pressure A unit internal pressure, P = 1,000 psi, is applied to the interior surfaces of the model. An end-cap load is applied to the free end of the nozzle piping in the form of tensile axial pressure, as calculated below.
P" IR,1000.
Pec 10.843752 2 2 Peci= (OR, -IR, (12.3752 _10.843752)= 3,307psi where, Pecl = End cap pressure on attached piping free end (psi)
P = Internal unit pressure (psi)
IRi = Inside radius of modeled piping (in) = 10.84375" (with cladding) [4]
ORi = Outside radius of modeled piping (in) =12.375" [4]
The internal pressure also induces an end-cap load on the axial free end of the modeled vessel shell, as calculated below.
P. IR,2 1000.126.52 (OR -JiR22 133.252_126.52)- 9,127 psi where, Pec2 = End cap pressure on vessel shell axial free end (psi)
P = Internal unit pressure (psi)
IR 2 = Inside radius of modeled vessel shell (in) = 126.5" (with cladding) [4]
OR 2 = Outside radius of modeled vessel shell (in) = 133.25" [4]
Symmetric boundary conditions are applied at the vessel's circumferential free end and the overall model's two planes of symmetry. The free end of the nozzle piping and axial free end of the vessel shell are coupled in their respective axial directions to simulate the remaining portions of the geometry not included in the model. The applied load and boundary conditions for the unit pressure load case are shown in Figure 3.
5.2 Thermal Transient Analyses The thermal transients to be analyzed for the NI nozzle are defined in Section 3.3, and are applied as follows.
5.2.1 Thermal Analyses Bulk fluid temperatures and heat transfer coefficients are applied to the inside surface nodes of the model. The nozzle and inside surface of the vessel are both subjected to a conservatively high convective heat transfer coefficient (HTC) of 10,000 Btu/hr-ft2 -°F, while the entirety of the outside File No.: 1400187.301 Page 6 of 20 Revision: 1 F0306-01RIR
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surface is assumed to be perfectly insulated with no heat transfer. Figure 4 depicts a representative plot of the thermal boundary conditions applied for the transient analyses.
5.2.2 Thermal Stress Analyses Symmetric boundary conditions are applied at the vessel's circumferential free end and the overall model's two planes of symmetry. The free end of the nozzle piping and axial free end of the vessel shell are coupled in their respective axial directions to simulate the remaining portions of the geometry not included in the model. Figure 5 shows a representative plot of the mechanical boundary conditions applied for the thermal transient stress analyses.
6.0 RESULTS 6.1 Overall Stress and Temperature Results A representative stress intensity contour plot for the unit pressure analysis is shown in Figure 6. Stress from the thermal transient is calculated. A representative temperature contour and total stress intensity contour plot for the Turbine Generator Trip SCRAM transient is shown in Figure 7 and Figure 8, respectively.
6.2 Through-Wall Stress Extractions In support of the future PFM analysis, four through-wall stress paths, two each at 00 and 900, are defined within the region of the NI nozzle blend radius and nozzle-to-vessel weld, as shown in Figure 9. Since the model is symmetric, these two paths also represent the stress at 180' and 2700, respectively. Stresses from all runs are extracted and saved in *.csv file format which can be imported to an Excel workbook for further processing (see Appendix A for file listings).
7.0 CONCLUSION
Unit pressure and thermal transient stress analyses have been performed. Stress results were extracted from all analyses for through-wall paths at locations of interest along the N I nozzle blend radius and nozzle-to-vessel weld in support of future PFM calculations. All of the stress results are stored in computer files for later use (see Appendix A for file listings).
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8.0 REFERENCES
- 1. Code Case N-702, "Alternative Requirements for Boiling Water Reactor (BWR) Nozzle Inner Radius and Nozzle-to-Shell Welds,Section XI, Division 1," February 20, 2004.
- 2. Safety Evaluation of Proprietary EPRI Report, "BWR Vessel and Internal Project, Technical Basis for the Reduction of Inspection Requirements for the Boiling Water Reactor Nozzle-to-Vessel Shell Welds and Nozzle Inner Radius (BWRVIP-108)," December 19, 2007, SI File No.
BWRVIP.108P.
- 3. BWR VIP-24 1. BWR Vessel Internal Project,ProbabilisticFractureMechanics Evaluationfor the Boiling Water Reactor Nozzle-to- Vessel Shell Welds and Nozzle Blend Radii, EPRI, Palo Alto, CA. 1021005. EPRI PROPRIETARY INFORMATION.
1400187.214.
- 5. Unit 1 Form N-I Manufacturers' Data Report for Nuclear Vessels, Revision 1, Contract 2867, SI File No. 1400187.203.
- 6. Unit 2 Form N-lA Manufacturers' Data Report for Nuclear Vessels, Contract 72-2046, SI File No. 1400187.204
- 7. ASME Boiler and Pressure Vessel Code,Section III, Material Properties, 1968 Edition through Winter 1969 Addenda.
- 8. ASME Boiler and Pressure Vessel Code,Section II, Part D, Material Properties, 2010 Edition.
- 9. Thermal Cycle Diagrams
- a. General Electric Drawing Number 158B8136, Sheet 1, Revision 6, "Reactor Vessel Nozzle Thermal Cycles," SI File No. 1400187.207
- b. General Electric Drawing Number 73 1E776, Sheets 1 and 2, Revision 3, "Reactor Vessel Thermal Cycles," LaSalle Unit 1, S1 File No. 1400187.205
- c. General Electric Drawing Number 761E581, Sheets 1 and 2, Revision 1, "Reactor Vessel Thermal Cycles," LaSalle Unit 2, SI File No. 1400187.206
- 10. ANSYS Mechanical APDL and PrepPost, Release 14.5 (w/ Service Pack 1), ANSYS, Inc.,
September 2012.
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Table 1: Bounding Transients for Analysis h,
Transient Time, Btu/hr-Description Number sec T, OF ft2-OF Turbine Trip 1 0 528 10000 SCRAM 4392 400 10000 9648 552 10000 Loss of Feedwater Pumps/ 2 0 525 10000 Isolation Valves Close 360 573 10000 370 561 10000 1260 561 10000 1680 490 10000 2160 573 10000 2170 561 10000 3240 561 10000 3660 485 10000 Note: A total of 3,660 seconds (in addition to the time shown) was added to the end of the transients to capture transient stress lag and to achieve a final transient steady state condition (see Section 3.3 of this calculation).
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Table 2: Material Properties for Low Alloy Steel SA-508 Class 2 / SA-533 Grade B, Class 1 Mean Young's Thermal Thermal Specific Temperature Modulus Expansion Conductivity Heat(')
(OF) (x10 6 psi) (xl0-6 in/in/*F) (x10"4 Btu/sec-in-OF) (Btu/lb-°F) 70 27.9 6.07 5.49 0.106 100 27.9(2) 6.13 5.46 0.107 150 27.8(2) 6.25 5.44 0.110 200 27.7 6.38 5.44 0.113 250 27.6(2) 6.49 5.42 0.116 300 27.4 6.60 5.42 0.119 350 27.2(2) 6.71 5.39 0.122 400 27.0 6.82 5.35 0.125 450 26.7(2) 6.92 5.32 0.128 500 26.4 7.02 5.25 0.130 550 26.1(2) 7.12 5.21 0.133 600 25.7 7.23 5.14 0.135 650 25.3(2) 7.33 5.07 0.138 700 24.8 7.41 5.00 0.141 Density (p) = 0.283 lb/in 3, assumed temperature independent.
Poisson's Ratio (u) = 0.3, assumed temperature independent.
Notes:
(1) Specific Heat values are derived from the equation shown in General Note (a) of Table TCD [8], Specific Heat = TC / (TD x density).
(2) Interpolated.
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Table 3: Material Properties for Stainless 308L (Treated as Type 304)
Mean Young's Thermal Thermal Specific Temperature Modulus Expansion Conductivity Heat0)
(OF) (xl0 6 psi) (x10 6 in/in/OF) (XI0"4 Btu/sec-in-OF) (Btu/lb-0 F) 70 27.4 9.11 1.99 0.116 100 27.3(2) 9.16 2.01 0.117 150 27.2(2) 9.25 2.08 0.120 200 27.1 9.34 2.15 0.122 250 27.0(2) 9.41 2.22 0.124 300 26.8 9.47 2.27 0.125 350 26.6(2) 9.53 2.34 0.127 400 26.4 9.59 2.41 0.129 450 26.2(2) 9.65 2.45 0.130 500 26.0 9.70 2.52 0.132 550 25.7(2) 9.76 2.57 0.132 600 25.4 9.82 2.62 0.133 650 25.2(2) 9.87 2.69 0.134 700 24.9 9.93 2.73 0.135 Density (p) = 0.283 lb/in 3, assumed temperature independent.
Poisson's Ratio (t) = 0.3, assumed temperature independent.
Notes:
(1) Specific Heat values are derived from the equation shown in General Note (a) of Table TCD [8], Specific Heat = TC / (TD x density).
(2) Interpolated.
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MAT1fl'H LOS Vipernoz Model 31D Figure 1: Components Included in the Finite Element Model File No.: 1400187.301 Page 12 of 20 Revision: I F0306-O1RIR
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LxS Figure 2: 3-D Finite Element Model Mesh for Analyses File No.: 1400187.301 Page 13 of 20 Revision: 1 F0306-OIRIR
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iYrT' NrIM Nozzle End Cap Pressure Vessel End Cap Pressure
~Symmetry
- I f.U 8001.66 2375.62 1250.41 125.2.07 1000 125041 LGS - Vipernoz Mxdel - 3D Figure 3: Applied Boundary Conditions and Unit Internal Pressure (Units for Pressure in terms of psi)
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2YW ~I WS - V-WL .,_- A a) Heat transfer coefficient (HTC)
ELM=
LZS - t z :-b) Bulk temperature (TBULK)
Figure 4: Applied Thermal Boundary Conditions for Thermal Transient Analyses (Turbine Generator Trip SCRAM shown, loads applied at end of transient)
(Units for HTC in terms of Btu/sec-in 2-°F, TBULK in *F)
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T",r NMrii Symmetrn 11S Vipernaz lMxel 3D)
Figure 5: Applied Mechanical Boundary Conditions for Thermal Stress Analyses File No.: 1400187.301 Page 16 of 20 Revision: 1 F0306-01RIR
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SimT (AWX)
RM 0 rMv .098Q298
- ý*w -i573.Z 7
ý-M -47723.9 1573.27[ 011/ 340.4 31468.2 42596.1 47"/23.9 WGS Vipernoz Model , 3D Figure 6: Total Stress Intensity Plot for Unit Internal Pressure (Units for stress intensity in terms of psi)
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S'INT-3 SUB -1 rJTD-46O2 .24 Stt' 404 .582 411.628 445.358 452.104 458.85 465.596 LGS Vipernoz Model 3D Figure 7: Temperature Contour for Turbine Generator Trip SCRAM at Time=4602.2 sec.
(Units for temperature in terms of *F)
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Irm'Z, Crll7ZTT'ZV 1IFP-27 SLUB -1 T'-,4602 .24 SINT (AVG)
!rW .426674
."-6885595 W -31478.2
%%Xi-44657. 4 3516.3 LGS Vipernoz Model 3D Figure 8: Stress Intensity Plot for Turbine Generator Trip SCRAM at Time=4602.2 sec.
(Units for stress intensity in terms of psi)
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MAT M 0' Fa(
LGS Vlpernoz M~del 3D Figure 9: Path Locations for Through-Wall Stress Extractions File No.: 1400187.301 Page 20 of 20 Revision: I F0306-OIRIR
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APPENDIX A COMPUTER FILENAMES File No.: 1400187.301 Page A-I of A-2 Revision: 1 F0306-OIRI
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File Name Description STACK.INP Controller input file to run thermal and mechanical analyses LGS.INP Input file to construct the 3-D model for linear-elastic analysis Input file of temperature dependent linear elastic material MPropLinearLGS.INP properties COMPONENTS.INP Component and boundary conditions definition file THMLGS_1 .INP Analysis input file for Transient 1 THMLGS_2.INP Analysis input file for Transient 2 LGSPRESS.INP Analysis input file for Unit Internal Pressure Load step definition file from thermal analysis THM *mntr.inp * = LGS 1, LGS 2 CMNTR.MAC Thermal temperature time history extraction macro file to create THM
- mntr.inp files GenStress.mac Path stress extraction macro file to extract *.CSV files GETPATH.TXT Through-wall path definition file Curve fit coefficients outputs of stresses in tabulated forms STR_*_COEP?.CSV * = PRESS, LGS_1, LGS_2
? = path number 1-10 File No.: 1400187.301 Page A-2 of A-2 Revision: 1 F0306-01 RI