Letter Sequence Other |
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Initiation
- Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request, Request
- Acceptance...
- Supplement, Supplement, Supplement, Supplement, Supplement, Supplement
Administration
- Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance, Withholding Request Acceptance
- Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting, Meeting
Results
Other: ML070370281, ML073100027, ML073510180, ML080360067, ML080430700, ML080500171, ML080530256, ML081010450, ML081010451, ML081120502, ML081700294, ML081720078, ML081760295, ML082040065, ML082050462, ML082100425, ML082810470, ML083120308, ML083240224, ML083250083, ML090130718, ML090340528, ML090720951, ML090760630, ML091320366, ML092020345, ML092430520, ML092440518, ML092460495, ML092460496, ML092460497, ML092460498, ML092460500, ML092540483, ML092680057, ML12319A076, ML13044A498
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MONTHYEARML0711503712007-04-24024 April 2007 Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Steam Dryer Evaluations Project stage: Request ML0712905652007-05-16016 May 2007 Withholding Information from Public Disclosure, Response to Nuclear Regulatory Commission (NRC) Request for Additional Information - Round 12 for Browns Ferry EPU: Supplemental to SBWB-64 Project stage: RAI ML0716303492007-06-15015 June 2007 Meeting with the Tennessee Valley Authority Concerning the Status of Browns Ferry Nuclear Plant, Units 1, 2 and 3, Steam Dryer Review Project stage: Meeting ML0718700242007-07-0303 July 2007 Technical Specifications (TS) Change TS-461 - Modification of Restart Large Transient Testing License Condition 2. (G) 2 - Supplement 1 Project stage: Request ML0717801902007-07-0505 July 2007 Request for Additional Information for Extended Power Uprate - Round 13 (TS-431 and TS-418 (TAC Nos. MD5262, MD5263, and MD5264) Project stage: RAI ML0719004762007-07-10010 July 2007 Meeting with the Tennessee Valley Authority (TVA) Concerning the Pending ACRS Meeting on the Browns Ferry Extended Power Uprate Project stage: Meeting ML0721501562007-07-18018 July 2007 Slides from Meeting with Tennessee Valley Authority on the Browns Ferry Power Uprate ACRS Presentation Project stage: Meeting ML0721303712007-07-27027 July 2007 Technical Specifications Changes TS-431 and TS-418, Extended Power Uprate - Steam Dryer Evaluations Project stage: Request ML0721400442007-08-0808 August 2007 Summary of Meeting with Tennessee Valley Authority on the Browns Ferry Power Uprate ACRS Presentation Project stage: Meeting ML0724805472007-08-31031 August 2007 Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Round 13 Request for Additional Information (RAI) - Containment Overpressure Project stage: Request ML0727606602007-10-0909 October 2007 Request for Additional Information for Extended Power Uprate - Round 14 (TS-418) Project stage: RAI ML0728902372007-10-18018 October 2007 Request for Withholding Information from Public Disclosure Concerning Round 13 Request for Additional Information for Browns Ferry Nuclear Plant (Tac Nos. MD5262, MD5263 and MD5264) Project stage: RAI ML0729603112007-10-22022 October 2007 Technical Specification (TS) Changes TS-431 & TS-418, Extended Power Uprate - EPU Large Transient Testing Project stage: Request ML0731000272007-11-0909 November 2007 Request for Schedule Regarding Analysis for Steam Dryers on Extended Power Uprate Amendment Requests (TAC Nos. MD5262, MD5263, and MD5264) (TS-431 and TS-418-S) Project stage: Other ML0732303482007-11-15015 November 2007 Units 1, 2, and 3 - Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Round 13 Request for Additional Information (RAI) - Containment Overpressure APLA-35/37 Project stage: Request ML0733304832007-11-21021 November 2007 Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Preliminary Findings on Steam Dryer Stress Analysis Project stage: Request ML0735101802007-12-14014 December 2007 Technical Specifications Changes TS-431 and TS-418 - Extended Power Uprate - Schedule Regarding Analysis for Steam Dryers Project stage: Other ML0734607572007-12-19019 December 2007 Request for Withholding Information from Public Disclosure for Browns Ferry Nuclear Plant (Tac No. MD5262, MD5263 and MD5264) Project stage: Withholding Request Acceptance ML0735400102008-01-25025 January 2008 Summary of Meeting with Tennessee Valley Authority on Steam Dryer Portion of the Extended Power Uprate Review (TAC Nos. MD5262, MD5263, and MD5264), Browns Ferry Units 1, 2, and 3 Project stage: Meeting ML0801504182008-01-25025 January 2008 Plants, Units 1, 2, and 3 - (Public Version) - Summary of December 10, 2007 Meeting with TVA on Steam Dryer Portion of the Extended Power Uprate Review Project stage: Meeting ML0803205212008-01-25025 January 2008 Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) Response to Round 15 Request for Additional Information (RAI) - APLA-38/40, SRXB-71, and SRXB-72 Project stage: Request ML0803600672008-01-25025 January 2008 Steam Dryer RAI 15 Status, Slides Project stage: Other ML0802501652008-01-30030 January 2008 Request for Withholding Information from Public Disclosure for Browns Ferry Nuclear Plant (Tac Nos. MD5262, MD5263, and MD5264) Project stage: Withholding Request Acceptance ML0803805602008-01-31031 January 2008 Technical Specifications (TS) Change TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Round 15 Request for Additional Information (RAI) Regarding Steam Dryer Analyses Project stage: Request ML0804307002008-02-11011 February 2008 Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Schedule Regarding EPU Project stage: Other ML0803503812008-02-14014 February 2008 Summary of Meeting with Tennessee Valley Authority - on Extended Power Uprate Review Project stage: Meeting ML0805302562008-02-21021 February 2008 Unit 1 - Technical Specifications (TS) Change TS-431 - Extended Power Uprate (EPU) - Fuels Methods Commitments Project stage: Other ML0806501012008-02-21021 February 2008 Response to Round 16 Request for Additional Information SRXB-73 Project stage: Request ML0804506472008-02-27027 February 2008 Request for Withholding Information from Public Disclosure Project stage: Withholding Request Acceptance ML0803506982008-02-29029 February 2008 Request for Additional Information for Extended Power Uprate - Round 16 (TS-431 and TS-418) (TACs MD5262, MD5263, MD5264) Project stage: RAI ML0807104982008-03-0606 March 2008 (BFN) - Units 1, 2, and 3 - Technical Specifications (TS) Change TS-418 and TS-431 - Extended Power Uprate (EPU) - Response to Round 16 Request for Additional Information (RAI) - SRXB-74/86 and SRXB-87 Through SRXB-90 Project stage: Request ML0811205102008-03-20020 March 2008 Summary of March 20, 2008, Meeting with Tennessee Valley Authority Regarding Steam Dryer Portion of the Extended Power Uprate Review (TAC Nos. MD5262, MD5263, and MD5264) - Slides Project stage: Meeting ML0810104512008-04-0404 April 2008 Technical Specifications (TS) Changes TS-431 and TS-418 Extended Power Uprate (EPU) BFN Steam Monitoring Plan Project stage: Other ML0810104502008-04-0404 April 2008 (BFN) - Units 1, 2, and 3 - Technical Specifications (TS) Changes TS-431 and TS-418 - Extended Power Uprate (EPU) - Response to Round 15 and Round 16 Requests for Additional Information (RAI) Regarding Steam Dryer Analyses Project stage: Other ML0817602952008-04-0909 April 2008 Units 1, 2, & 3 - Technical Specifications Changes TS-431 and TS-418 - Extended Power Uprate - Confirmation of Commitment Completions Project stage: Other ML0811205022008-04-16016 April 2008 CDI Incoming Letter Dated April 16, 2008 Regarding NRC Presentation Entitled, Tennessee Valley Authority Browns Ferry Nuclear Plant - Extended Power Uprate Steam Dryers. Project stage: Other ML0811302312008-04-17017 April 2008 Public Slides - Summary of April 17, 2008, Meeting Regarding Steam Dryer Portion of the Extended Power Uprate Review, Project stage: Meeting ML0811200332008-04-30030 April 2008 Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Request for Withholding Information from Public Disclosure for Round 15 Fuels Responses Project stage: Withholding Request Acceptance ML0812806272008-05-0101 May 2008 Technical Specifications Change TS-418, Extended Power Uprate Supplemental Response to Round 16 Request for Additional Information - SRXB-87 & SRXB-89 Project stage: Supplement ML0813502222008-05-0202 May 2008 Request for Additional Information for Extended Power Uprate - Round 17 (TS-431 and TS-410) Project stage: RAI ML0805001712008-05-0202 May 2008 - Schedule Regarding Analysis for Steam Dryers on Extended Power Uprate Amendment Requests (TAC Nos. MD5262, MD5263, and MD5264) (TS-431 and TS-418) Project stage: Other ML0812804712008-05-0202 May 2008 Request for Additional Information for Extended Power Uprate - Round 17 Project stage: RAI ML0813602912008-05-22022 May 2008 Summary of April 17, 2008, Meeting Regarding Steam Dryer Portion of the Extended Power Uprate Review Project stage: Meeting ML0815805532008-05-22022 May 2008 Summary of 5/22/08 Meeting Regarding Containment Overpressure Portion of the Extended Power Uprate Review - Browns Ferry - Handouts Project stage: Meeting ML0810604452008-06-0202 June 2008 Request for Withholding Information from Public Disclosure for Partial Round 13 Responses (Tacs. MD5262, MD5263 and MD5264) Project stage: Withholding Request Acceptance ML0810606162008-06-0202 June 2008 Request for Withholding Information from Public Disclosure for Browns Ferry Nuclear Plant Project stage: Withholding Request Acceptance ML0810607222008-06-0202 June 2008 Request for Withholding Information from Public Disclosure for Partial Response to Round 13 Project stage: Withholding Request Acceptance ML0816403252008-06-0303 June 2008 Units 2 & 3 - Technical Specifications Change TS-418 - Extended Power Uprate - Supplemental Response to Round 16 Request for Additional Information - SRXB-88 Project stage: Supplement ML0812607122008-06-0505 June 2008 Summary of Meeting with TVA Steam Dryer Portion of the Extended Power Uprate Review Project stage: Meeting ML0817002942008-06-12012 June 2008 Technical Specifications Changes TS-431 and TS-418 - Extended Power Uprate - Response to ACRS Conclusions and Recommendations Regarding Containment Overpressure Credit Project stage: Other 2008-01-30
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Category:Calculation
MONTHYEARML16123A1492016-04-30030 April 2016 Transmittal of 2015 Annual Radioactive Effluent Release Report, and Revisions 22 and 23 to the Offsite Dose Calculation Manual CNL-14-068, (Bfn), Units 1, 2 and 3 - Supplement to Proposed Technical Specification Change to Revise the Leakage Rate Through MSIVs (TS-485)2015-01-29029 January 2015 (Bfn), Units 1, 2 and 3 - Supplement to Proposed Technical Specification Change to Revise the Leakage Rate Through MSIVs (TS-485) ML14015A4042013-11-22022 November 2013 Attachment 6 - NDQ099920010019 - Ex-Containment Removal Coefficients for Alternative Source Term Analyses, Through Attachment 11 - List of Regulatory Commitments ML12123A0182011-07-0505 July 2011 0-ODCM-001, Revision 0021, Offsite Dose Calculation Manual, Enclosure 5 ML1012604712010-04-30030 April 2010 Enclosure 5, Browns Ferry Nuclear Plant Offsite Dose Calculation Manual 0-OCDM-001, Revision 20 ML0924604982009-08-19019 August 2009 Calculation Package 0900833.302, Rev. 0, Steam Dryer Hood Stiffener Stress Relief Modification Stress Reduction Factor (Srf) Computation, Enclosure 4 ML0912802642009-04-30030 April 2009 Offsite Dose Calculation Manual 0-ODCM-001, Revision 0019 ML0910002912009-04-0303 April 2009 (BFN) - Unit 1 - Technical Specifications (TS) Change TS-431 - Extended Power Uprate (EPU) - Response to Round 23 Request for Additional Information (RAI) EMCB.205 and EMCB.206 ML0918201692009-01-27027 January 2009 Letter from F. Godwin, TVA to NRC on Browns Ferry Proposed Request for Exemption from 10 CFR 50, Appendix R. Paragraph lll.G.2, Fire Protection of Safe Shutdown Capacity ML0902203942009-01-0808 January 2009 Response to Round 23 RAI Technical Specifications Changes TS-431 and TS-418, Extended Power Uprate, Enclosure 2 - Structural Integrity Associates, Inc. Calculation Package 0006982.304, Revision 1 and Encls 4 and 5 ML0831203082008-10-30030 October 2008 Calculation Package 0006982.304, Extended Power Uprate Main Steam Line Strain Gauge Vibration Monitoring. ML0817500812008-06-16016 June 2008 Encl. 6, Calculation Package 0006982.301, Extended Power Uprate Main Steam Line Strain Gage Vibration Monitoring, and Encl. 7, Response to Round 15 Group 4 and Round 17 Request for Additional Information ML0721303822007-07-31031 July 2007 CDI Report No. 07-06NP, Revision 0, Finite Element Model for Stress Assessment of Browns Ferry, Unit 2 & 2 Steam Dryer to 250 Hz ML0721303752007-07-31031 July 2007 CDI Report No. 07-05NP, Revision 0, Finite Element Model for Stress Assessment of Browns Ferry, Unit 1, Steam Dryer to 250 Hz ML0721303862007-07-31031 July 2007 CDI Report No. 07-09NP, Revision 0, Methodology to Predict Full Scale Steam Dryer Loads from In-Plant Measurements, with Inclusion of a Low Frequency Hydrodynamic Contribution ML0721304152007-07-31031 July 2007 CDI Report No. 07-11NP, Revision 0, Dynamics of BWR Steam Dryer Components ML0721304292007-07-31031 July 2007 C.D.I. Technical Memorandum No. 07-26NP, Revision 0, Comparison of Browns Ferry Unit 1 & Unit 2 Main Steam Line Strain Gage / Pressure Readings ML0721304012007-07-31031 July 2007 CDI Report No. 07-10NP, Revision 0, Acoustic and Low Frequency Hydrodynamic Loads at CLTP Power Level on Browns Ferry, Unit 2, Steam Dryer to 250 Hz ML0625103822006-08-21021 August 2006 Enclosure 2, Browns Ferry, Units 1, 2 & 3 - Calculation MDQ099920060011, Revision 1, Transient Npsh/Containment Pressure Evaluation of RHR and Core Spray Pumps. ML0625103742006-08-21021 August 2006 Enclosure 1, Browns Ferry, Units 1, 2 & 3 - Calculation MDQ0999970046, Rev 10, NPSH Evaluation of Browns Ferry RHR and CS Pumps. ML0622300632006-08-0404 August 2006 Calculation MDQ099920060011, Rev. 0, Transient Npsh/Containment Pressure Evaluation of RHR and Core Spray Pumps. ML0622300582006-08-0404 August 2006 Calculation MDQ099970046, Rev. 9, NPSH Evaluation of Browns Ferry RHR and CS Pumps. ML0608804692006-03-23023 March 2006 Calculation MDQ0999970046 NPSH Evaluation of Browns Ferry RHR and CS Pumps ML0608804152006-03-0909 March 2006 Calculation MDQ0999970046, Rev. 008, NPSH Evaluation of Browns Ferry RHR and CS Pumps ML0512506002005-04-28028 April 2005 Offsite Dose Calculation Manual, Revision 0016 ML0507703702005-03-11011 March 2005 Technical Specifications (TS) Change TS-447, Request for Additional Information (RAI) - Extension of Channel Calibration Surveillance Requirement Performance Frequency and Allowable Value Revision ML0612206472005-02-0404 February 2005 Offsite Dose Calculation Manual, Revision 17 ML0603806772004-06-0909 June 2004 TVA Calculation CDQ1 074 2004 0160, Rev 0, HCLPF Calculations of RHR Heat Exchanger Anchorage for Seismic IPEEE Program. ML0603806762004-06-0909 June 2004 TVA Calculation CDQ1 999 2004 0156, Rev. 0, HCLPF Calculations of MCC Anchorage for Seismic IPEEE Program. ML0614405592004-03-0606 March 2004 Enclosure 5, Browns Ferry, Units 1, 2 & 3 - Changes to the Offsite Dose Calculation Manual 2004, Rev 16 ML0424500612004-03-0404 March 2004 Calculation CDN1-000-2004, Seismic Verification of Condenser and Its Anchorage, MSIV Ruggedness Seismic Analysis - Resolution of Pos 15-1. ML0603806721996-06-14014 June 1996 Calculation CD-Q0000-940339, Rev. 1, Calculation of Basic Parameters for A46 and Individual Plant Examination of External Events (IPEEE) Seismic Program. 2016-04-30
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Text
ENCLOSURE 4 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT I TECHNICAL SPECIFICATIONS (TS) CHANGE TS-431 EXTENDED POWER UPRATE (EPU)
STRUCTURAL INTEGRITY ASSOCIATES, INC. CALCULATION PACKAGE 0900833.302, REVISION 0, "STEAM DRYER HOOD STIFFENER STRESS RELIEF MODIFICATION STRESS REDUCTION FACTOR (SRF) COMPUTATION" Attached is Structural Integrity Associates, Inc. Calculation Package 0900833.302, "Steam Dryer Hood Stiffener Stress Relief Modification Stress Reduction Factor (SRF) Computation."
StructuralIntegrityAssociates, Inc. File No.: 0900833.302 CALCULATION PACKAGE Project No.: 0900833 [ Q E- Non-Q PROJECT NAME:
BFN Steam Dryer Technical Support CONTRACT NO.:
63268 CWA P5160 CLIENT: PLANT: Browns Ferry Units 1, 2 & 3 Tennessee Valley Authority (TVA)
CALCULATION TITLE:
Steam Dryer Hood Stiffener Stress Relief Modification Stress Reduction Factor (SRF) Computation D Project Manager Preparer(s) &
Document Affected Revision Description Approval Checker(s)
Revision Pages Signature& Date Signatures & Date 0 1-17, Initial Issue At, tfOAZI' Computer Files K.K. Fujikawa 08/19/09 S. B. Kok 08/19/09 M. Qin 08/19/09 Page 1 of 17 F0306-O IRO
V Structural Integrity Associates, Inc.
Table of Contents 1.0 IN TRODU CTION ........................................................................................................................ 4 2.0 METHODOLOGY / ASSUMPTIONS / MATERIAL PROPERTIES .................................... 5 3.0 STRESS RELIEF SCHEM E .................................................................................................... 6 4.0 STIFFEN ER ANA LY SIS .................................................................................................... 7 4.1 Key D im ensions .............................................................................................. ......... 7 4.2 Boundary Conditions and Applied Load ......................................................................... 8 4.3 Solid Finite Elem ent M odel ............................................................................................. 9 4.4 Solid M odel Stress Paths .............................................................................................. 10 4.5 Solid M odel Results ........................................................................................................... 11 4.6 Stress Com parison ............................................................................................................. 15 5.0 CON CLU SION S ........................................................................................................................ 16 6.0 REFEREN CES ........................................................................................................................... 17 Appendix A - Com puter Files ............................................................................................................. Al File No.: 0900833.302 Page 2 of 17 Revision: 0 F0306-OIRO
V StructuralIntegrity Associates, Inc.
List of Tables Table 4-1 Stiffener M odel Key D im ensions ..................................................................................... 7 Table 4-2 Stiffener Solid Model Maximum Stress Intensity ........................................................... 13 Table 4-3 Stiffener Solid Model / Shell Model Stress Ratio ........................................................... 15 List of Figures Figure 3-1 Hood Stiffener Stress Relief Scheme .............................................................................. 6 Figure 4-1 Stiffener Model Boundary Conditions and Applied Load .............................................. 8 Figure 4-2 Stiffener Solid Finite Element Model Mesh (Isometric View) ........................................ 9 Figure 4-3 Stiffener Solid M odel Stress Paths ................................................................................ 10 Figure 4-4 Stiffener Solid Model Stress Intensity at High Stress Region (View 1)............................ 11 Figure 4-5 Stiffener Solid Model Stress Intensity at High Stress Region (View 2) ....................... 12 File No.: 0900833.302 Page 3 of 17 Revision: 0 F0306-OIRO
StructuralIntegrityAssociates, Inc.
1.0 INTRODUCTION
Background
The Browns Ferry steam dryer has been analyzed using a shell finite element model, which does not specifically model the weld at connections between plate members. The results show that there are localized high stresses due to structural discontinuity at some of the welded connections. Based on past experience, it has been established that if the connections are modeled using solid elements to represent the weld, the weld can better distribute the stresses in the region of high stress discontinuity. Coupled with the use of the stress linearization approach, the maximum stress intensity computed using the solid model (with the weld modeled) generally gives a better prediction of stresses compared with shell elements in region of high structural discontinuity.
The computation of the stress reduction factor (SRF) for the hood stiffener is documented in Reference 1. The computed SRF for the hood stiffener is 0.79.
In order to achieve a stress reduction at the peak stress location at the bottom of the stiffener / hood connection, a number of stress relief schemes have been considered. A parametric study of a stress relief modification involving the use of a semi-circular cut-out near the peak stress location has been performed and this study is documented in Reference 2. This study forms the basis of the stress relief approach adopted in this calculation.
Obiective This calculation documents the stress analysis and the computation of the SRF for a hood stiffener with a stress relief scheme. This stress relief scheme places a semi-elliptical cut-out (with a major radius of 1.75" and a minor radius of 1.25") at the bottom of the stiffener. The edge of this cut-out is located at 3/16" from the edge of the fillet weld (see Figure 3-1).
The finite element analyses in this calculation are performed using ANSYS Version 11.0 (Reference 5).
File No.: 0900833.302 Page 4 of 17 Revision: 0 F0306-OlRO
V StructuralIntegrity Associates, Inc.
2.0 METHODOLOGY / ASSUMPTIONS / MATERIAL PROPERTIES The methodology, assumptions, and material properties used in this calculation are similar to those used in Reference 1. For completeness, some of the key parameters are summarized in this section.
Unit Load Application A unit load of 1,000 lb is applied to the bottom 1.75" section of the stiffener. This unit load is applied to the solid sub-model. The computation of the SRF is based on stresses resulted from the unit load application.
Material Properties The material properties for A-240, Type 304 stainless steel (Reference 3) at 550'F are used for the analysis. Similar material properties are assumed for the weld.
The material properties used are as follows:
Modulus of Elasticity 25.55E6 psi (Reference 4, Page 12)
Poisson's Ratio 0.30 (Reference 4, Page 12)
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3.0 STRESS RELIEF SCHEME The stress relief scheme for the hood stiffener consists of placing a semi-elliptical cut-out at the bottom of the stiffener. The dimensions of this semi-elliptical hole are 1.75" (major radius) by 1.25" (minor radius). The edge of this cut-out is located at 3/16" away from the edge of the fillet weld. An illustration of the stress relief scheme is shown in Figure 3-1.
AN STIFFENER FILLET WELD HOOD BASE PLATE 0.1875" -A Figure 3-1 Hood Stiffener Stress Relief Scheme File No.: 0900833.302 Page 6 of 17 Revision: 0 F0306-0 I RO
StructuralIntegrity Associates, Inc.
4.0 STIFFENER ANALYSIS The stiffener sub-model consists of three key parts: the stiffener, the hood, and the base plate.
4.1 Key Dimensions The key dimensions of the sub-model are as follows [1, Table 4-1]:
Table 4-1 Stiffener Model Key Dimensions Thickness / Size Modeled Dimensions Component (in) (in x in)
Stiffener 1/4" 10" (width) x 34" (height)
Hood 1/2" 56" (depth) x 34" (height)
Base Plate 1/2" 56" (depth) x 7" (width)
Weld ( 3/16" Along the entire connection.
Note: (1) The fillet weld is modeled in the solid sub-model, on both sides.
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4.2 Boundary Conditions and Applied Load The boundary conditions and applied load are identified in Figure 4-1 [1, Figure 4-1].
AN Hood Edge A Edge A Base
- Stiffener Base Plate tery S1,000 Brown lb EdgeC Browns Ferry Stiffener Weld Figure 4-1 Stiffener Model Boundary Conditions and Applied Load Boundary Conditions Edge A: Plane of symmetry.
Edge B: Restrained in Y translation, and rotation about X and Z.
Edge C: Plane of symmetry, and restrained from translation in X.
Applied Load Load: 1,000 lb is evenly applied at the bottom 1.75" section of the stiffener.
File No.: 0900833.302 Page 8 of 17 Revision: 0 F0306-O1RO
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4.3 Solid Finite Element Model The solid finite element model is modeled using SOLID45 elements. Variable mesh sizes, with finer mesh around the region of high stress concentration and coarser mesh away from the high stress concentration region, are used. Six layers of elements are modeled across the plate thickness, therefore, providing adequate discretization through the plate thickness to capture the stress variations across the thickness. The entire model consists of approximately 320,000 nodes and 375,000 solid elements. The finite element mesh is shown in Figure 4-2.
Figure 4-2 Stiffener Solid Finite Element Model Mesh (Isometric View)
File No.: 0900833.302 Page 9 of 17 Revision: 0 F0306-O1RO
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4.4 Solid Model Stress Paths Linearization stress paths are taken from the weld root to the component surface in the vicinity of the high stress region. In addition, linearization stress paths are also taken from the weld toe to the opposite surface of the connecting parts. The stress paths used for the stiffener solid model are shown in Figure 4-3.
I I I I 7 8 7 Figure 4-3 Stiffener Solid Model Stress Paths File No.: 0900833.302 Page 10 of 17 Revision: 0 F0306-OIRO
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4.5 Solid Model Results The stress intensity plots for the solid model are provided in Figure 4-4 and Figure 4-5.
Figure 4-4 Stiffener Solid Model Stress Intensity at High Stress Region (View 1)
File No.: 0900833.302 Page 11 of 17 Revision: 0 F0306-01 RO
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Figure 4-5 Stiffener Solid Model Stress Intensity at High Stress Region (View 2)
File No.: 0900833.302 Page 12 of 17 Revision: 0 F0306-01 RO
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Maximum Stress Intensity The stress intensity is computed for the different stress paths. There are multiple locations for each of the paths, and the largest magnitude is identified as the maximum stress intensity for that path.
The maximum stress intensity for the different paths are summarized in Table 4-2.
Table 4-2 Stiffener Solid Model Maximum Stress Intensity Location P. + Pb (psi)
Path 1 4,737 Path 2 4,084 Path 3 5,154 Path 4 4,737 Path 5 .4,084 Path 6 5,154 Path 7 2,855 Path 8 3,559 Path 9 5,109 Cut-Out '* 7,771 Note: (1) The stress intensity at the cut-out is not subject to weld factor of 1.8 [6, Figure 3]. Since the stress intensity of 7,771 psi for the cut-out is less than the stress intensity of 5,154 psi x 1.8 (weld factor) for Paths 3 and 6, the stress at the cut-out does not govern.
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Other Observation The placement of the cut-out at the bottom of the stiffener directs the load path away from the bottom of the stiffener. Since the cut-out is located a short distance (i.e., 3/16") away from the fillet weld, the geometry prevents the load path from returning to the bottom of the stiffener as it approaches the weld. The increased flexibility introduced by the cut-out at the base of the stiffener /
hood connection causes the load, and hence the stress, to shift upward. As a result, the maximum stress intensity for the stress relief modification is located at approximately 0.7" from the base. This is consistent with the findings documented in Reference 2.
File No.: 0900833.302 Page 14 of 17 Revision: 0 F0306-0 1RO
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4.6 Stress Comparison The stress comparison between the shell and the solid finite element models is summarized in Table 4-3.
Table 4-3 Stiffener Solid Model / Shell Model Stress Ratio Pm +Pb Solid Shell (psi) (psi) 1 4,737 0.48 2 4,084 0.42 3 5,154 0.53 4 4,737 0.48 5 4,084 9,8090() 0.42 6 5,154 0.53 7 2,855 0.29 8 3,559 0.36 9 5,109 0.52 Maximum= 0.53 Note: This value is taken from Reference 1.
Summary The maximum SRF for the solid model stress intensity / shell model stress intensity is 0.53.
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5.0 CONCLUSION
With the use of the stress relief modification, the solid model / shell model SRF for the hood stiffener has been reduced from 0.79 (without the stress relief scheme as documented in Reference 1) to 0.53. This ratio is applicable to the stiffener shell stress intensity at the bottom of the welded connection between the stiffener and the hood.
File No.: 0900833.302 Page 16 of 17 Revision: 0 F0306-O IRO
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6.0 REFERENCES
- 1. SI Calculation No. 0006982.301, "Shell and Solid Sub-Model Finite Element Stress Comparison," Revision 2, SI File No. BFN-15-301.
- 2. SI Calculation No. 0900833.301, " Hood Stiffener Plate Stress Relief Scheme Parametric Study,"
Revision 0, SI File No. 0900833.301.
- 3. Email with attachments from George Nelson (TVA) to Marcos Herrera (SI) on 04/22/08 at 9:02 am, "Steam Dryer - Drain Channel," SI File No. BFN-15-224.
- 4. Email with attachment from Rick Cutsinger (TVA) to Soo Bee Kok (SI) on May 20, 2008 @9:02 am, "RE: Weld Structure Evaluation," SI File No. BFN-15-227.
- 5. ANSYS Mechanical and PrepPost w/ Service Pack I (ANSYS 11.0 SPI), May 2009.
- 6. GE Report DRF GE-NE 0000-0039-4817-1, "Recommended Weld Quality and Stress Concentration Factors For use in the Structural Analysis of Exelon Replacement Steam Dryer,"
April, 2005.
File No.: 090083 3.302 Page 17 of 17 Revision: 0 F0306-01 RO
V StructuralIntegrity Associates, Inc.
Appendix A - Computer Files Filename Description StiffSM7.inp Stiffener Solid Model analysis input.
StiffSM7PP.inp Stiffener Solid Model post-processing input.
StiffenerSummarySM7.xls Stiffener result summary spreadsheet.
File No.: 0900833.302 Page Al of A]
Revision: 0 F0306-OIRO