ML093360327
| ML093360327 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/22/2009 |
| From: | Hiremagalur J, Rodamaker S FirstEnergy Nuclear Operating Co, Structural Integrity Associates |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| L-09-268, TAC ME0477, TAC ME0478 0800368.322, Rev. 1 | |
| Download: ML093360327 (21) | |
Text
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File No.: 0800368.322 CALCULATION PACKAGE Project No.: 0800368 Quality Program: [D Nuclear [: Commercial PROJECT NAME:
Davis Besse Phase 2 Alloy 600 CONTRACT NO.:
49151 Rev, I CLIENT:
PLANT:
Welding Services Inc.. (WSI)
Davis-Besse Nuclear Power Station. Unit I CALCULATION TITLE:
Finite Element Models of the Reactor Coolant Pump Discharge Nozzle with Weld Overlay Repair Document Affected Project Manager Preparer(s) &
Revision Pages Revision Description Approval Checker(s)
Signature & Date Signatures & Date 0
1 -19 Initial Issue A-I -A-2 Computer Files
/ R.
.Bax S"C. Rodainaker 5/22/09 5/22/09 J Hifr~eagalur 5/22/09 Page 1 of 19 F0306-0IRI
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Table of Contents 1.0 OBJECTIVE.......................................................................................................
4 2.0 TECHNICAL APPROACH.................................................................................
4 3.0 A SSUM PTION S / DESIGN INPUTS....................................................................
4 4.0 FINITE ELEM ENT M ODELS.............................................................................
5 4.1 N ozzle-to-Safe End W eld................................................................................
6 4.2 Safe End-to-Piping W eld...............................................................................
6 4.3 ID W eld Repair...............................................................................................
6 4.4 Cold Leg Spray N ozzle.................................................................................
7 4.5 Cold Leg Pressure Tap N ozzle......................................................................
7 4.6 Weld Nuggets and Layers.....................................
7 4.7 M aterials........................................................................................................
8 4.8 Loads and M echanical Boundary Conditions.................................................
8 5.0 RESULTS...........................................................................................................
8 6.0 REFEREN CES...................................................................................................
10 APPEN DIX A AN SY S INPUT FILES........................................................................
A -1 List of Tables Table 1: Com ponent M aterials........................................................................................
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List of Figures Figure 1. Reactor Coolant Pump Discharge Nozzle Dimensions Used........................ 11 Figure 2. Reactor Coolant Pump Discharge Nozzle, Safe End, and Weld Dimensions U se d....................................................................................................................
12 Figure 3. Reactor Coolant Pump Discharge Safe End, Safe End-to-Piping Weld, ID Weld Repair, and Attached Piping Dimensions Used...................................
13 Figure 4. Cold Leg Spray Nozzle Dimensions Used...................................................
14 Figure 5. Pressure Tap Nozzle Dimensions Used........................................................
15 Figure 6. W eld Layer and "Nugget" Layout.................................................................
16 Figure 7. 2-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle for Residual Stress (Min. OWOL Dims.).........................
17 Figure 8. 3-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle (M ax. FSW OL Dims.)......................................................
18 Figure 9. 3-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle (M in. OW OL Dims.)........................................................
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1.0 OBJECTIVE A weld overlay repair is being designed for the Reactor Coolant Pump Safe End-to-Piping Welds at Davis-Besse Nuclear Power Station, Unit 1. The purpose of this calculation package is to document the development of the finite element models which will be used to perform residual and operational stress analyses for later crack growth and ASME Code,Section III qualifications.
2.0 TECHNICAL APPROACH Three finite element models are developed using the ANSYS finite element analysis software [1].
One model is constructed as a 2-dimensional (2-D) axisymmetric model using the "optimized" minimum weld overlay thickness and length dimensions, which will later be used to determine residual stresses resulting from the welding process. The second and third finite element models are constructed as 3-dimensional (3-D) "half-symmetry" models, which will later be used to determine structural and thermal operational stresses. One of the 3-D models is constructed using "full structural" maximum dimensions for the weld overlay, whereas the other is constructed using "optimized" minimum overlay dimensions.
The models include the reactor coolant pump discharge nozzle, the nozzle-to-safe end weld, the safe end, the safe end-to-piping weld and weld butter, a postulated ID weld repair, a portion of attached cold leg piping (elbow) and cladding, the stainless steel buffer layer, the cold leg spray nozzle, the pressure tap and associated weld, and the weld overlay repair.
3.0 ASSUMPTIONS / DESIGN INPUTS The "optimized" and "full structural" weld overla desi s are shown in References 2 and 9
- =A number of assumptions were made during development of the finite element models, which are listed as follows:
An ID weld repair is assumed to have been applied to the safe end-to-piping weld, as documented in MRP-169, Section 4.2 [4]. The dimensions used for the repair are assumed, as indicated in Figure 3. The ID weld repair is only modeled in the 2-D residual stress analysis for simulation purposes, since the adjacent materials are identical it does not affect the structural and stress results.
o The spray nozzle-to-safe end attachment weld was not specifically modeled. In addition the spray nozzle itself was simplified with only the thickest portion of the nozzle modeled. More dimensional details for the spray nozzle is provided in Figure 4.
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S
- The 3-dimensional models included a Spray Nozzle, which is only present on RCP 2-2.
The presence of the Spray Nozzle bounds the remaining RCP locations as it adds stiffness to the structure, reduces the total amount of overlay material and provides for more thermal stress effects.
o The 3-dimensional models included a Pressure Tap Nozzle, which is only present on RCP 2-2 and 2-1. The presence of the Pressure Tap Nozzle bounds the remaining RCP locations as it adds stiffness to the structure, reduces the total amount of overlay material and provides for more thermal stress effects.
o For the 2-Dimensional residual stress model, the minimum "optimized" weld overlay thickness and length dimensions are extracted from Reference 2. Since the weld overlay repair impacts the fillet radius of the spray nozzle a revised shorter length corresponding to the length where the weld overlay repair taper touches the spray fillet is used. This corresponds to a weld overlay repair 0.51 inches shorter in length which is conservative since the beneficial stresses will be reduced for the overlay. From the minimum "optimized" weld overlay design the height at Station D is called out as 0.68 inches, but is modeled as 0.52 inches due to the required exclusion of the piping elbow, which is again conservative due to the reduction in thickness.
o Two separate 3-dimensional models are modeled; one using the minimum "optimized" weld overlay (OWOL) thickness and length dimensions from Reference 2, and the other using the maximum "full structural" weld overlay (FSWOL) dimensions from Reference
- 9. Using the minimum "optimized" dimensions is intended to produce conservative stresses for primary loading (pressure and mechanical piping loads) analyses, whereas using the maximum "full structural" dimensions is intended to produce conservative stresses for secondary loading (thermal) evaluations.
o Additional dimensional assumptions were necessary and are indicated in Figures 2 through 5.
4.0 FINITE ELEMENT MODELS Three finite element models are constructed. The 2-dimensional axisymmetric model is constructed using the 4-node structural solid element, PLANE 182 (the thermal equivalent for the thermal analyses is PLANE55).
The second and third models are 3-dimensional (3-D) models, which are constructed using the 8 and 20-node brick elements, SOLID45 and SOLID95 (the thermal equivalent for thermal analyses is SOLID70 and SOLID90, respectively). Due to the symmetric layout of the nozzle, a 1800 (half-symmetry) section of the nozzle is modeled. The two 3-D models differ only in the thickness and File No.: 0800368.322 Page 5 of 19 Revision: 0 F0306-01R1I
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length of the weld overlay (one model uses the maximum "full structural" dimensions; the other uses minimum "optimized" dimensions).
All three models include:
" A portion of the reactor coolant pump discharge nozzle o The nozzle-to-safe end weld e
The safe end
- The safe end-to-piping weld and weld butter o A portion of the cold leg piping/elbow o A portion of the cold leg piping/elbow cladding o The stainless steel buffer layer
" The weld overlay repair o A postulated ID weld repair of the safe end-to-pipe weld
- The Cold Leg Spray Nozzle (Included in 3-D models only)
" Pressure Tap Nozzle (Included in 3-D models only) o Pressure Tap Nozzle weld (Included in 3-D models only)
The dimensions used to generate the models are shown in Figures 1 through 5. The figures include the respective references and indicate those dimensions that are assumed.
The 2-dimensional model is shown in Figure 7, and the 3-dimensional models are shown in Figures 8 and 9.
4.1 Nozzle-to-Safe End Weld 4.2 Safe End-to-Piping Weld Details of the safe end-to-pipe weld preparation were provided in References 3 and 7. Reference 7 provides as-built dimensions. Figure 3 indicates the dimensions that were modeled.
4.3 ID Weld Repair An ID weld repair is assumed to have been applied to the safe end-to-elbow weld. Section 4.2 of MRP-169 [4] indicates that "...one must start with a highly unfavorable, pre-overlay residual stress condition such as that which would result from an ID surface weld repair...," but does not define the extent of the repair that would meet this condition. The finite element model examples provided in Section 5.0 and Section 8.0 of MRP-169 use 50% through wall repairs. However, all of the example nozzles have diameters less than 14 inches and wall thicknesses less than 1.5 inches. The modeled discharge nozzle File No.: 0800368.322 Page 6 of 19 Revision: 0 F0306-01RII
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safe end-to-elbow weld is 3.1 inches thick with an inside diameter of 28 inches. Based on prior experience with a large bore residual mockup, a 25% ID weld repair (resulting in a repair depth of 0.725 inch) will be modeled and should generate "... a highly unfavorable, pre-overlay residual stress condition..." The dimensions used for the repair are assumed, as indicated in Figure 3.
4.4 Cold Leg Spray Nozzle 4.5 Cold Leg Pressure Tap Nozzle 4.6 Weld Nuggets and Layers The 2-dimensional model (see Figure 6) will be used to determine residual stresses resulting from the ID weld repair and the weld overlay repair. The nozzle-to-safe end weld and safe end-to-pipe weld will not be included in the residual stress determination as the resulting stress state will be conservatively assumed to be zero, as studies have shown [5] that the as-welded (butt weld) stress state is typically compressive at the ID surface. Imposing the residual effect of the ID repair on a zero stress state is conservative, as this increases the tensile stresses at the ID. Reference 5 documents that even with the significant compressive stresses of the as-welded butt weld, the residual stress state of the final ID repair is adverse, with significant axial and hoop tensile stresses.
The regions of weld overlay and weld repair are divided into a number of layers by which the welding process will be simulated. In a later residual calculation, the layers will be further sub-divided into nuggets. These "nuggets" will represent a grouping of weld bead passes, which subdivide the weld layers. The number of layers was determined using an average bead thickness of approximately 0.1 inches. See Figure 4 for weld layer layout.
S 0
The ID weld repair is performed in eight layers.
The weld overlay is performed in nine layers.
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4.7 Materials The following materials were used for the modeled components:
Table 1: Component Materials Component Material Reactor Coolant Pump Discharge Nozzle A-351, Grade CF8M [6]
Nozzle-to-Safe End Weld Stainless Steel Type 316 (Assumed)
Safe End A-376, Type 316 [6]
Safe End-to-Pipe Weld and Butter Alloy 82/182 [6]
Cold Leg Piping (elbow)
A-516, Grade 70 [6]
Cold Leg Piping (elbow) Cladding A-240-304L [6]
ID Weld Repair of Safe End-to-Pipe Weld Alloy 82/182 (Assumed)
Weld Overlay Buffer Layer ER-308L [2, 9]
Weld Overlay Repair Alloy 52M [2, 9]
Spray Nozzle A-182 F316 [6]
Pressure Tap Nozzle A-336 Cl. F8M [6]
Pressure Tap Nozzle Weld Stainless Steel Type 316 (Assumed)
The structural material properties used for the finite element models were previously developed in Reference 6. Reference 6 includes two ANSYS material property files. The first, "MPropLinearDB.INP," includes temperature dependent linear elastic and thermal material properties. This file is intended for the thermal transient and mechanical loads analyses (including pressure and axial/moment loads), which will be used for the stress evaluations in support of the ASME Code,Section III qualification and crack growth evaluations. The second file, "MProp_MISONLinear DB.INP," again includes temperature dependent linear elastic and thermal material properties, but also includes temperature-dependent non-linear material properties. This file is intended to be used for the residual stress evaluations in support of future crack growth evaluations.
These files are called directly within their respective finite element model input files.
4.8 Loads and Mechanical Boundary Conditions No loads or boundary conditions of any kind are included in the finite element models at this time.
Specific loads and boundary conditions, appropriate to the specific analysis, will be applied in subsequent stress evaluations to be performed in later calculation packages.
5.0 RESULTS Three finite element models of the Reactor Coolant Pump Discharge Nozzle were developed to support stress analyses and residual stress determinations. The 3-dimensional models, shown in Figures 8 and 9, are intended to be used for linear elastic stress analyses for use in later ASME Code,Section III qualifications and crack growth evaluations. The input files for these ANSYS models are DB-OUTLET-File No.: 0800368.322 Revision: 0 Page 8 of 19 F0306-O1Rl:
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MIN.INP and DB-OUTLET-MAX.INP. The files generate two ANSYS database files named DB-OUTLET-MfN.DB and DB-OUTLET-MAX.DB, which can be resumed for subsequent linear elastic evaluations. The 2-dimensional model, shown in Figure 7, is intended to be used for non-linear residual stress analyses whose results will then be used in future crack growth evaluations. The input file for the ANSYS model is DB-OUTLET-RES.INP. The file generates an ANSYS database file named DB-OUTLET-RES.DB, which can be resumed for the subsequent residual stress evaluations.
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6.0 REFERENCES
- 1. ANSYS/Mechanical, Release 8.1 (w/Service Pack 1), ANSYS Inc., June 2004.
- 2. SI Drawing No. 0800368.520, Sheet 1 of 3, "RCP Discharge Nozzle Optimized Weld Overlay Design," SI File No. 0800368.520 (for revision refer to SI Project Revision Log, latest revision).
- 3. FirstEnergy Specification No. M-496Q, "Technical Specification for Mitigation of Alloy 600/182/82 Welds for The First Energy Company Davis-Besse Nuclear Power Station, Unit 1, Oak Harbor, Ohio," SI File No. 0800368.201.
- 4. Materials Reliability Program: Technical Basis for Preemptive Weld Overlays for Alloy 82/182 Butt Welds in PWRs (MRP-169), EPRI, Palo Alto, CA, and Structural Integrity Associates, Inc., San Jose, CA: 2005. 1012843.
- 5. Materials Reliability Program: Welding Residual and Operating Stresses in PWR Plant Alloy 182 Butt Welds (MRP-106), EPRI, Palo Alto, CA: 2003. 1009378.
- 6. SI Calculation No. 0800368.301, "Material Properties for Davis-Besse Unit 1, RCP Suction, RCP Discharge, Cold Leg Drain and Core Flood Nozzles Preemptive Weld Overlay Repairs,"
(for revision refer to SI Project Revision Log, latest revision).
- 7. EPRI DM Report IR-2005-95, Revised page 10-1 and 10-3, "Davis-Besse Unit 1 Reactor 1i Lirawing iNo. U6?UU05.Y4U, bneet i Of 4, --KLr Ulscnarge iNozzie Puii mructural (FSWOL) Weld Overlay Design," SI File No. 0800368.540 (for revision refer to SI Project PA%7icrn~n T ne lt1-pf rpir,ýi~nn' File No.: 0800368.322 Revision: 0 Page 10 of 19 F0306-01RF
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7]
7
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Figure 1. Reactor Coolant Pump Discharge Nozzle Dimensions Used File No.: 0800368.322 Revision: 0 Page 11 of 19 F0306-O1R1l
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Figure 2. Reactor Coolant Pump Discharge Nozzle, Safe End, and Weld Dimensions Used File No.: 0800368.322 Page 12 of 19 Revision: 0 F0306-01R1
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Figure 3. Reactor Coolant Pump Discharge Safe End, Safe End-to-Piping Weld, ID Weld Repair, and Attached Piping Dimensions Used File No.: 0800368.322 Page 13 of 19 Revision: 0 F0306-01RlI
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[As-Modeled)
[As-Modeled]
[As-Modeled]
'm"os
- Based on the relative orientation of the 0.75" pressure tap nozzle and cold leg pipe,
[Reference 10, Pages 30, 31, and 33].
The 7.75" length is deduced to be towards the safe end-to-pipe weld.
Figure 4. Cold Leg Spray Nozzle Dimensions Used File No.: 0800368.322 Revision: 0 Page 14 of 19 F0306-O1Rl
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W, I-Ozon 44 Lý-
Figure 5. Pressure Tap Nozzle Dimensions Used File No.: 0800368.322 Revision: 0 Page 15 of 19 F0306-01RE
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Layer 9 (Alloy 52M)
Layer 8 (Alloy 52M)
Layer 7 (Alloy 52M)
Layer 6 (Alloy 52M)
Layer I (Alloy 52M)
Layer 5 (Alloy 52M)
Layer 4 (Alloy 52M)
Layer 3 (Alloy 52M)
Layer 2 (Alloy 52M)
/ Layer I (ER308L)
Ag 1
Layer 8-'
Figure 6. Weld Layer and "Nugget" Layout File No.: 0800368.322 Revision: 0 Page 16 of 19 F0306-01RI
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I giffim RCP Outlct Nozzlc Figure 7. 2-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle for Residual Stress (Min. OWOL Dims.)
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ELEMENTS MAT NUM AN PLOT NO.
I Figure 8. 3-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle (Max. FSWOL Dims.)
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ELEMENTS NAT NUM AN PLOT NO.
1 RCP Outlet Nozzle Figure 9. 3-Dimensional ANSYS Finite Element Model of Reactor Coolant Pump Discharge Nozzle (Min. OWOL Dims.)
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APPENDIX A ANSYS INPUT FILES File No.: 0800368.322 Revision: 0 Page A-I of A-2 F0306-O1R1
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File Name Description ANSYS input file to construct 3-dimensional model of Davis-Besse DB-OUTLET-MAX.INP Reactor Coolant Pump Discharge Nozzle (max. WOL dimensions for linear-elastic analysis).
ANSYS input file to construct 3-dimensional model of Davis-Besse DB-OUTLET-MIN.INP Reactor Coolant Pump Discharge Nozzle (min. WOL dimensions for linear-elastic analysis).
ANSYS input file to construct 2-dimensional model of Davis-Besse DB-OUTLET-RES.INP Reactor Coolant Pump Discharge Nozzle (min. WOL dimensions for non-linear residual stress analysis).
ANSYS input file of temperature dependent linear elastic material MPropLinear_DB.INP properties, called by DB-OUTLET-MAX.INP and DB-OUTLET-MIN.INP. File developed previously in Reference 6.
ANSYS input file of temperature dependent linear elastic and MProp_MISONLinearDB.INP temperature dependent non-linear material properties, called by DB-OUTLET-RES.INP. File developed previously in Reference 6.
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