ML14149A407

From kanterella
Revision as of 08:51, 28 June 2018 by StriderTol (talk | contribs) (Created page by program invented by StriderTol)
Jump to navigation Jump to search
Palo Verde, Unit 3 - Calculation 32-9220624-000, Natural Frequency and Structural Integrity Analysis, (Non-Proprietary), Attachment 6
ML14149A407
Person / Time
Site: Palo Verde Arizona Public Service icon.png
Issue date: 04/18/2014
From: Barnes K
AREVA
To:
Office of Nuclear Reactor Regulation
References
102-06879-JJC-JHK-DCE 32-9220624-000
Download: ML14149A407 (34)
v • d • e


Text

{{#Wiki_filter:EnclosureRelief Request 52 Proposed Alternative in Accordance with10 CFR 50.55a(a)(3)(i)ATTACHMENT 6Natural Frequency and Structural Integrity Analysis 0402-01-FOI (Rev. 018, 01/30/2014)A CALCULATION SUMMARY SHEET (CSS)AREVADocument No. 32 -9220624 -000 Safety Related: MYes El NoNatural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle RepairTitle (Non-Proprietary)I PURPOSE AND SUMMARY OF RESULTS:AREVA Inc. Proprietary information in the document is indicated by pairs of braces" [1.,,PurposeThe purpose of this analysis is to find the natural frequency and analyze the structural integrity of the Palo VerdeNuclear Generating Station, Unit 3 (PVNGS3) Reactor Vessel Bottom Mounted Instrumentation (BMI) RemnantNozzle after repair.Summary of ResultsAs presented in Section 6.2, the remnant nozzle's natural frequencies are compared with the vortex shedding andother primary excitations on nozzle #3. There is no potential of excitation of the nozzle with the vortex shedding,nor with other dynamic loads analyzed herein.As discussed in Section 6.3, the Limit Load Analysis per NB-3228.1 as performed through the finite elementanalysis with ANSYS indicates that the lower bound collapse has not been reached even with a factor of 2 beingapplied to the internal pressure and all primary nozzle loads. It is concluded that the remnant nozzle and the weldwith a flawed region as analyzed herein retains its structural integrity through the plant normal operation.This is the non-proprietary version of 32-9216967-001.The total number of pages in this calculation is 33. This includes pages 1-26 and Appendix A (A-1 to A-7).THE DOCUMENT CONTAINSASSUMPTIONS THAT SHALL BETHE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT: VERIFIED PRIOR TO USECODENERSION/REV CODENERSION/REV w YesANSYS 14.5.7/Windows 7 x64 __ NoANSYS 14.0 (See Section 5.1.2)Enclosure Attachment 6Page 1 of 33 A 0402-01-FOI (Rev. 018, 01/30/2014)AR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Review Method: N Design Review (Detailed Check)-1 Alternate CalculationSignature BlockPages/SectionsPrepared/Revlewed/ApprovedAll except Section 5.1.2 and AppendixASection 5.1.2 and Appendix A-INote: P/RWA designates Preparer (P), Reviewer (R), Approver (A);LP/LR designates Lead Preparer (LP), Lead Reviewer (LR)Project Manager Approval of Customer References (NIA If not applicable)Name rTitle(printed or typed) (printed or typed) Signature DateMaya Chandrashekhar Project Manager ../I--//*[Mentoring Information (not required per 0402-01)Name Title Mentor to:(printed or typed) (printed or typed) (P/R) Signature DateN/AEnclosure Attachment 6Page 2 AAREVA0402-01-FOl (Rev. 018, 01/30/2014)Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Record of RevisionRevision Pages/Sections/ParagraphsNo. Changed Brief Description / Change Authorization000 All Initial IssueEnclosure Attachment 6 Page 3Enclosure Attachment 6Page 3 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table of ContentsPageSIG NATURE BLOCK ................................................................................................................................ 2RECO RD O F REVISIO N .......................................................................................................................... 3LIST O F TABLES ..................................................................................................................................... 6LIST O F FIG URES ................................................................................................................................... 71.0 PURPO SE ..................................................................................................................................... 82.0 ANALYTICAL M ETHO DO LOGY ............................................................................................... 83.0 ASSUM PTIO NS ............................................................................................................................ 93.1 Unverified Assumptions ............................................................................................................. 93.2 Justified Assumptions ........................................................................................................................ 93.3 Modeling Simplifications .......................................................................................................... 94.0 DESIG N INPUT ........................................................................................................................... 104 .1 D im e n s io n s ...................................................................................................................................... 1 04 .2 M a te ria ls .......................................................................................................................................... 1 04.3 Primary Loads for Structural Integrity Analysis (Section 6.3) ..................................................... 114.3.1 Internal Pressure ......................................................................................................... 114.3.2 Remnant Nozzle Loadings ........................................................................................... 115.0 CO M PUTER SO FTW ARE .......................................................................................................... 125 .1 S o ftw a re .......................................................................................................................................... 1 25.1.1 Main Body Computer Software .................................................................................... 125.1.2 Appendix A Computer Software ................................................................................. 125 .2 C o m p ute r F ile s ................................................................................................................................ 126.0 CALCULATIO NS ......................................................................................................................... 146 .1 M o d e l ............................................................................................................................................... 1 46.1.1 Structural Boundary Conditions ................................................................................. 166.1.2 Primary Load Application for Structural Integrity Analysis .......................................... 166.2 Natural Frequency Analysis ...................................................................................................... 176.2.1 Remnant Nozzle Load Evaluation ............................................................................... 186.3 Structural Integrity Analysis ...................................................................................................... 197.0 CO NCLUSIO N ............................................................................................................................ 2

58.0 REFERENCES

............................................................................................................................ 26Enclosure Attachment 6 Page 4 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table of Contents(continued)PageAPPENDIX A : NOZZLE CRACKED REGION ............................................................................... A-1Enclosure Attachment 6 Page 5Enclosure Attachment 6Page 5 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)List of TablesPageTable 5-1: Computer Files .................................................................................................................... 12Table A-i: UT Data for Flaw Indications 1 through 4 ........................................................................... A-3Table A-2: UT Data for Flaw Indications 5 through 10 ......................................................................... A-4Table A-3: Calculation of Nozzle Cutout (1) ......................................................................................... A-5Table A-4: Calculation of Nozzle Cutout (2) ......................................................................................... A-6Enclosure Attachment 6Page 6 AAREVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)List of FiguresPageF ig ure 6-1: W indow Location ................................................................................................................. 14Figure 6-2: 3-D Solid Model Geometry with Window ....................................................................... 15Figure 6-3: M eshed FEA M odel ........................................................................................................ 16Figure 6-4: Remnant Nozzle First Mode ............................................................................................ 18Figure 6-5: Strain Results at 1 x Primary Loads (Remnant Nozzle and Weld) ................................. 20Figure 6-6: Strain Results at 1 x Primary Loads (Remnant Nozzle Only) ......................................... 21Figure 6-7: Strain Results at 1.5 x Primary Loads (Remnant Nozzle and Weld) ............................... 22Figure 6-8: Strain Results at 1.5 x Primary Loads (Remnant Nozzle Only) ....................................... 23Figure 6-9: Stress Results at 1 x Primary Loads (Remnant Nozzle and Weld) ............................... 24Figure 6-10: Stress Results at 1.5 x Primary Loads (Remnant Nozzle and Weld) ........................... 25Figure A-I: Reference Positions for UT Inspection Data ..................................................................... A-2Figure A-2: N ozzle C racked R egion .................................................................................................... A-7Enclosure Attachment 6Page 7 AARIEVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)1.0 PURPOSEAn inspection of Alloy 600 Bottom Mounted Instrument (BMI) nozzles in 2013 identified potential coolantleakage between the interface of the RVBH (reactor vessel bottom head) penetration #3 and the BMI nozzle atPalo Verde Nuclear Station Unit 3 (PVNS3). Although a half-nozzle repair performed on nozzle #3 moved theprimary pressure boundary from the original J-groove partial penetration weld at the inner surface of the vessel toa new J-groove partial penetration weld at an outer surface weld pad, there remains a concern that cracks in theremnant nozzle may propagate over the remaining life of the plant.The remaining function of the remnant nozzle consists of two parts:1. Provide a path for the incore instrumentation cable.2. Maintain structural integrity so as to limit the size of a DBA break under a hypothetical failure of the J-groove weld on the new external pad pressure boundary. That is, the size of the break opening wouldremain the same as that of the attached [ ] ID tubing, which is the same as the current design of theother internal welded BMI nozzles that use the anti-ejection feature.These design functions are accomplished by demonstrating structural stability of the remnant nozzle and weldjoint. The effect of the cracks in the nozzle and degraded weld on the structural stability of the remnant nozzle areconservatively evaluated to calculate the potential reduction in stiffness and its corresponding natural frequency toensure that a resonant condition does not exist when subjected to the flow induced vibratory loads of the RCSsystem.AREVA Document 51-9220420 (latest revision) provides a road map of the AREVA analyses for the Palo VerdeBMI Nozzle.The purpose of this calculation is to determine the natural frequency of the remnant nozzle and evaluate itsstructural integrity, considering any circumferential extension of the lack of fusion zone and flawed material dueto crack growth. The natural frequency will be compared to the excitation of primary dynamic loads to determineif resonance may occur. The structural integrity of the nozzle will be determined by demonstrating there is nocollapse mechanism formed by loads as high as 1.5 times maximum primary loads using ASME Code LimitAnalysis (Reference [1]) as a guide. Although the remnant nozzle is no longer considered to be a primary pressureboundary component, it is convenient to use ASME Code Section III as a guideline for determining the structuralintegrity of the nozzle. Primary loads imposed on the remnant nozzle at penetration #3 that need to be addressedinclude deadweight, pressure, seismic, pump excitation, white noise excitation, and hydraulic flow.2.0 ANALYTICAL METHODOLOGYThe general methodology of model development and analysis consists of:1) Use the three-dimensional model developed for the Section III analysis (Reference [2]) and modify toinclude the lack of fusion between the weld and remnant nozzle due to the cracking found. The cracksidentified in BMI nozzle 3 were contained within a circumferential arc of approximately [] (See Appendix A), centered approximately at the uphill side of the nozzle. Thiscircumferential region of cracking will be assumed to exhibit a complete loss of fusion between thenozzle and remnant J-groove weld over the full axial depth of the weld. The model is alsoconservatively considered to have a complete loss of materialin the flawed zone within a window ofthe size [ ] by [ ] (see Section 4.1 and Appendix A for details). It will alsoconsider corrosion between the BMI remnant nozzle #3 and the RVBH.2) The natural frequencies of the remnant nozzle will be calculated using the finite element modeldeveloped to reflect the loss of fusion at the interface between the nozzle and J-groove weld. ThisEnclosure Attachment 6 Page 8 AAR EVADocument No. 32-9220624-.000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)frequency will be compared to the vortex shedding frequency and the excitation of other primarydynamic loads.3) Use primary loadings on the BMI nozzle #3 including deadweight, pressure, seismic, pumpexcitation, white noise excitation, and hydraulic flow and apply to the finite element model asdeveloped in the Section III analysis. These will be modified as necessary based on the frequencyfound in Step 2.4) Run a limit load analysis to obtain the total strains for the nozzle and J-groove weld material. Ensureno collapse mechanism forms at the nozzle to weld junction for loadings up to 1.5 times themaximum primary loads.3.0 ASSUMPTIONS3.1Unverified AssumptionsThere are no unverified assumptions within this calculation.3.2 Justified AssumptionsThis circumferential region of cracking is conservatively assumed to exhibit a complete loss of fusion between thenozzle and remnant J-groove weld over the full axial depth of the weld over the flawed region identified inReference [3].3.3Modeling SimplificationsOne boat sample is included in the finite element model. The boat excavation will be modeled at the plane ofsymmetry on the uphill side (i.e., most critical location). This modeling simplification allows a 180 degree finiteelement model in lieu of 360 degrees.To account for the flaws in the remnant nozzle a "window" is cut in the nozzle with the size calculated inAppendix A. This window bounds the flawed area in the remnant nozzle and the area where there is loss of fusionbetween the nozzle and remnant J-groove weld. It is conservative to consider the loss of material for the flawedregion while in reality there is only a loss of rigidity due to crack propagation.Enclosure Attachment 6Page 9 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)4.0 DESIGN INPUT4.1DimensionsMajor nominal dimensions are the same as Reference [2] and are summarized below:RVBH inside radius to base metalRVBH base metal thickness (min.)Cladding ThicknessButtering ThicknessBMI Remnant Nozzle OD at weldBMI Remnant Nozzle ID at weldJIIIIIBMI Repair Nozzle OD [ jBMI Repair Nozzle ID = [ ]Weld Pad Height = [The cracks identified in BMI nozzle 3 were contained within a circumferential arc of approximately [] (See Appendix A based on Reference [3] and calculation in Section 6.1), centered approximately at theuphill side of the nozzle. This circumferential region of cracking is assumed to exhibit a complete loss of fusionbetween the nozzle and remnant J-groove weld over the full axial depth of the weld.The window cut out to simulate the portion of nozzle having flawed material starts at [ ] above thehorizontal datum (where the nozzle ID tapers to [ ] ). and the bottom of the window is ] I .It hasa total height of [ I and is " ] wide circumferentially. See Appendix A for dimension details.4.2 MaterialsMaterial designations are listed in Section 6.0 of Reference [4]. For existing materials, material properties to beused in the finite element analysis are taken from Reference [5]. For replacement materials, material properties aretaken from Reference [6]. Material properties for each component are tabulated in Reference [2].RVBHBMI Remnant NozzleCladdingButteringJ-Groove WeldRepair Weld FillerReplacement Half Nozzle[CCCCCExistingExistingExisting (non-structural)I Existing, use [I Existing, use [Replacement, use [IIIReplacementEnclosure Attachment 6 Page 10Enclosure Attachment 6Page 10 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)4.3 Primary Loads for Structural Integrity Analysis (Section 6.3)4.3.1 Internal PressurePer Reference [4], the design temperature and pressure are [ J and [ , respectively. Thedesign pressure is used as the maximum normal operating pressure.Since secondary stress due to thermal is self-relieving and not considered part of the analysis a uniformtemperature of [ ] (Tunif=Tref in ANSYS, no differential thermal growth) is applied throughout themodel and a uniform pressure of [ ] (conservative) on all surfaces in contact with the primarycoolant. These surfaces include the RVBH interior, the original J-groove weld, the head bore, the weld pad bore,the remaining and replacement BMI nozzle inside diameter and the remaining and replacement BMI nozzleoutside diameter which is inside the head bore. In addition, the bottom end of the replacement BMI nozzle alsohas the pressure applied to represent the hydrostatic end cap pressure.4.3.2 Remnant Nozzle LoadingsPer Reference [7] the remnant nozzle inside the vessel experiences the following external loads, which describedon Pages A-582 to A-585 of Reference [7]:Fluid Flow Pressure (HF)Pump Periodic Excitation (PPE)Seismic Accelerations (SSE)Mechanical White Noise Excitation (WN)The nozzle loadings used in Reference [2] based on References [7] and [8] are reviewed for resonance based onthe natural frequency found and are used or updated as necessary. Since the nozzle loads are reversible, they willall be applied in the same direction at the same time. Two cases will be considered, one in the positive x directionand one in the negative x direction. See Figure 6-2 for the coordinates.Enclosure Attachment 6 Page iiEnclosure Attachment 6Page '11 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)5.0 COMPUTER SOFTWAREAll computer files generated for this analysis and the Installation Test files have been uploaded to AREVAColdStor found in the following directory: "\cold\General-Access\32\32-9000000\32-9216967-000\official". Allfiles are listed in Table 5-1.5.1SoftwareMain Body Computer Software5.1.1ANSYS Release 14.5.7 (Reference [9]) is used in this calculation. Verification tests are listed as follows:* Computer programs tested: ANSYS Release 14.5.7." Verification Tests: VM246 for SOLID186 and SOLID187 elements." Computer hardware used: DELL Precision (Service Tag# 5VM76S 1, computer name "KBARNES3") withWindows 7 Enterprise Service Pack 1, 64 bit Operating System with 8 GB of RAM available." Name of person running the tests: Kristine Barnes." Date of tests: 2/7/2014.5.1.2Appendix A Computer SoftwareANSYS Release 14.0 (Reference [10]) is used in this calculation. The software was used for determining the sizeand position of the flaws in the welds and it is acceptable to use the earlier version. Verification tests are listed asfollows:" Computer programs tested: ANSYS Release 14.0.* Verification Tests: VM 111 for the PLANE55 element (element type is arbitrary for the purpose of AppendixA)." Computer hardware used: DELL Precision (Service Tag# 5VN36S 1, computer name "DKILLIAN4") withWindows 7 Enterprise Service Pack 1L 64 bit Operating System with 8 GB of RAM available." Name of person running the tests: Doug Killian." Date of tests: 2/11/2014.5.2Computer FilesThe following table lists the computer files associated with the natural frequency and structural integrity of thePV3 RV BMI Nozzle Repair.Table 5-1: Computer FilesFile Name Date DescriptionGeometryFEM nodes/elements written from ANSYS WorkbenchGeom-cut.dat 01/14/2014 for frequency and structural analysis.Geom cut Modal.out 01/16/2014 Output creating model .db file for frequency analysis(Section 6.2).Geom cutStr.out 01/16/2014 Output creating model .db file for structural integrityI analysis (Section 6.3).Enclosure Attachment 6Page 12 AAREVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)File Name Date DescriptionBoundary Conditions/MaterialsmatDef modal.mac 01/16/2014 Material definitions for frequency analysis (read by-__Geom cut Modal, Section 6.2).Material definitions for structural integrity analysis (reade aby Geom cut str, Section 6.3).Structural boundary conditions written from ANSYSbc st symm.mac 01/14/2014 Workbench (read by each analysis).Natural Frequency Analysis (Section 6.2)Modal Cut.out 01/16/2014 Output documenting modal natural frequency analysis.I Reads database from Geom cut Modal.Structural Integrity Analysis (Section 6.3)Output documenting the structural analysis with loadsLoadLimitSSEPos.out 03/06/2014 for the structural integrity determination. Reads databasefrom Geom cut Str.LoadLimitSSEPos Post.out 03/06/2014 Post Processing for LoadLimitSSEPos.outOutput documenting the structural analysis with loadsLoadLimitSSENeg.out 03/06/2014 for the structural integrity determination. Reads databasefrom Geom cut Str.Load LimitSSENegPost.out 03/06/2014 Post Processing for Load Limit SSENeg.outLCISSENegPost.dat 03/06/2014LC1_SSEPosPost.dat 03/06/2014LC2_SSENegPost.dat 03/06/2014LC2 SSEPos Post.dat 03/06/2014LC3_SSENegPost.dat 03/06/2014Stress and Strain Results from the Load Limit Analyses.LC3 SSEPos Post.dat 03/06/2014LC4 SSENeg Post.dat 03/06/2014LC4 SSEPos Post.dat 03/06/2014LC5_SSENeg__Post.dat 03/06/2014LC5 SSEPosPost.dat 03/06/2014Appendix AFlaws.out 03/04/2014 Draws lines between the end points of each flawindication and then extends the skewed flaws until theyFlaws.output 03/04/2014 intersect the extended axial flaws.Determines the size and position of the cracked regionFlaw Indications.xlsx 01/29/2014 fo lw~uptIfrom Flaws.output.Verification FilesVerification run for SOLID 186 and SOLID 187VM246.out 02/07/20 14elmnselements.vml I 1.vrt 02/11/2014 Verification run for PLANE 55 used in Appendix A.Enclosure Attachment 6Page 13 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)6.0 CALCULATIONS6.1 ModelThe 3-D solid model simulates a [ ] section of BMI Nozzle #3 and a portion of the adjacent ReactorVessel Bottom Head. The model is similar to the model used in Reference [2], with the major difference beingthe window cut out to account for the actual cracks on the nozzle and weld.The window is located [ ] above the horizontal datum (where the nozzle ID tapers to [the bottom of the window is ] as shown in Figure 6-1. It has a total height of [[ ] wide circumferentially (see Appendix A).] ) and] and isRemnant Nozzle[][1I[-3[NNTSFigure 6-1: Window LocationFor modeling the cutout in a half model, half of the total circumferential width is considered [ t[ ] due to symmetry). With an OD of [ Jthe total circumference of the remnant nozzleThe angle of the window for the half model is:E ]Enclosure Attachment 6Page '14 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Therefore, the window will be modeled for a [ ] portion of the nozzle. This is in the same location that theexisting weld is unfused from the nozzle and bounds the flawed weld locations.No contact elements are included in the model to account for the corrosion between the pipe and the RVBH. Thecorrosion rate was found to be [ I over [ ] of operation (Reference [11]). The maximumdisplacement for the entire nozzle at design loadings is [ ] (LCl_SSENeg_Post.dat, See Section 6.3).Therefore, the remnant nozzle will not interact with the RVBH head.The model geometry is built with ANSYS Workbench [9] and is shown in Figure 6-2. The model is meshedwithin the ANSYS Workbench environment. The meshed FEA model is shown in Figure 6-3. The meshedWorkbench model is written to Geom cut.dat which is used to create the two models for the frequency andstructural analysis (Geom cutModal.out and Geom cutStr.out).Figure 6-2: 3-D Solid Model Geometry with WindowEnclosure Attachment 6 Page 15Enclosure Attachment 6Page 15 AAR EVA Document No. 32-9220624-000Natural Frequencyand Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-3: Meshed FEA Model6.1.1Structural Boundary ConditionsSymmetric boundary conditions are applied to the nodes that lie on the plane of symmetry of the model viaANSYS file bc_stsymm.mac. These symmetric boundary conditions allow in-plane displacements (i.e., radialgrowth) while restricting all out-of-plane displacements.6.1.2 Primary Load Application for Structural Integrity AnalysisInside surfaces which are in contact with the fluid are loaded with the appropriate internal pressure. Thesesurfaces include: RVBH interior, remnant nozzle OD and top surface within the vessel, remnant nozzle andreplacement nozzle ID, remnant nozzle and replacement nozzle within the head bore, RVBH bore, and cut ends ofremnant and replacement nozzle within the bore. In addition, an end-cap pressure is applied to the external end ofthe repair nozzle to simulate the hydrostatic pressure which is present in the full system. The exterior of theRVBH and repair nozzle are not loaded by pressure.Enclosure Attachment 6Page 16 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair. (Non-Proprietary)EndCapPress= Pressure x (Inside Radius)2/ ((Outside Radius)2 -(Inside Radius)2)The remnant nozzle loads are applied as a concentrated load at the mid-height of the nozzle. Since the model onlyincludes 180 degrees of the nozzle and weld, the loads are divided by 2 when applied. For the Pump PeriodicExcitation (PPE) and White Noise Excitation (WN), the resultant of the force calculated in Reference [2] is used:t ]The seismic loads are also calculated based on a resultant force in the horizontal direction in Reference [2]:The Fluid Flow Pressure or Hydrolic Flow Load (HF) is a single load in the horizontal direction and does notneed to use a resultant of two directions: I I as calculated in Reference [2].6.2 Natural Frequency AnalysisThe bottom mounted nozzles are subjected to hydraulic loads as the reactor coolant emerges from the downcomerregion and turns to flow through the fuel assemblies. Of particular concern are cross flows that could potentiallyexcite vortex shedding vibration modes or pump excitation modes for the remnant nozzle. The natural frequenciesof the remnant nozzle must be calculated to ensure no resonance with the vortex shedding or excitation of otherdynamic loads.To perform the frequency analysis, the material for the nozzle was modified to account for the water mass in thenozzle and displaced by the nozzle as done previously in Reference [7]. In Reference [7] on pg. A-524, thevolumes of the solid nozzle and void space are calculated for nozzle #1. The nozzle is similar in size to nozzle #3,and it is acceptable to use the volumes calculated previously to find the necessary increase in material density toaccount for water mass. The window cut out is not considered in the following density calculation since it is afictitious window and the material is still present in reality.Per Reference [7], the solid volume is [ ] and the void volume is [ .Therefore, the totalvolume of water that must be accounted for is:[ ITherefore the weight of water is (water density = [ 0.0266 lb/in3 ] , Reference [7]):[ IThe total weight of steel is (steel density [ 0.304 lb/in3 ] , Reference [7]):[Therefore, the increase in weight is:I JWhen the cut model is run with a factor of 1.111 for the nozzle density, the modal analysis produces the first fewfrequencies as registered in the output file "ModalCut.out." The lowest frequency is found to be:[ I with [ ] mass participation in the [ , first mode shownin Figure 6-4.Enclosure Attachment 6Page '17 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)The next lowest frequency of [ ] does not demonstrate participation from the nozzle. The next modethat shows participation from the nozzle is the 3rd mode with a frequency of [Figure 6-4: Remnant Nozzle First Mode6.2.1 Remnant Nozzle Load EvaluationBased on the new natural frequency, each remnant nozzle load listed in Section 6.1.2 is evaluated to ensure thereis no resonance:Fluid Flow Pressure (HF): The vortex shedding frequency for nozzles #1-40 is [ I (Reference [7],pg. A-527). This is much lower than the first natural frequency of nozzle #3, therefore, there will be no excitationof the nozzle due to the vortex sheading frequency.Pump Periodic Excitation (PPE): The frequency is not close to either of the pump excitations at [] (C [] separation either way). Therefore, the previous load used at [ (Reference [7])is still acceptable.Seismic Accelerations (SSE): The seismic accelerations used are peak values as calculated in Reference [2].Therefore, the natural frequency has no effect on the load.Mechanical White Noise Excitation (WN): The white noise band covers frequencies up to [ ]Therefore, the. natural frequency has no effect on the load.Enclosure Attachment 6 Page 18Enclosure Attachment 6Page 18 AAREVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)6.3 Structural Integrity AnalysisAlthough the remnant nozzle is no longer considered to be a primary pressure boundary component, it isconvenient to use ASME Code Section III (Reference [1]) as a guideline. As such the Limit Analysis detailed inSection NB-3228.1 is used as a guideline for determining if the remnant nozzle and J-groove weld will remainstructurally intact during plant operation. Per Section NB-3228. 1, the maximum loadings should not be greaterthan 2/3 of the lower bound collapse load. Thus, 1.5 times all primary loadings will be checked to ensure nocollapse mechanism forms. Since the analysis is only concerned about the remnant nozzle becoming a loose part,and not concerned with maintaining an ASME pressure boundary, fatigue evaluation on the remnant nozzle is notperformed herein. The crack growth evaluation of the remnant nozzle is performed in AREVA Document 32-9217241 (latest revision).The material properties are updated for this model so that the materials are all elastic-perfectly plastic inmatDefLL.mac. The yield strength used is 1.5Sim as prescribed by NB-3228.1 of Reference [I].Yield Stress for remnant nozzle ( [ ] ) is 23.3 ksi x 1.5 = 34.95 ksi Reference [5]Yield Stress for the RVBH ( [ I ) is 26.7 ksi x 1.5 = 40.05 ksi Reference [5]Yield Stress for the cladding (non-structural, ] ] ) is 16.7 ksi x 1.5 = 25.05 ksi Reference [5]Yield Stress for the replacement nozzle and weld [ ] is 23.3 ksi x 1.5 = 34.95 ksi Reference [6]For the limit analysis, the applied primary loads including deadweight, pressure ( [ ] ), seismic ( [] ), pump excitation ( [ ] ), whitenoise excitation ( [ ] ), and hydraulic flow ( [ ] ) are taken from Reference [2] and applied atmid-height of the remnant nozzle as a concentrated load. The loads are increased incrementally using a multiplierfrom I to 2 by an increment of 0.25 (numbered as Load Cases 1-5). Note that even with a factor of 2, ANSYS stillprovides a converged solution indicating the lower bound collapse loads have not been reached. The analysis isrun for the two worst case scenarios: (1) all loads applied in the positive x-direction (LoadLimitSSEPos.out)and (2) all loads applied in the negative x-direction (LoadLimit SSENeg.out). The external loads along with thepressure ensure that all load combinations are bounded. See Figure 6-2 for the coordinates.The limit analysis is documented in LoadLimitSSEPos.out and LoadLimitSSENeg.out. Stresses and strainsare printed to files LC(x)_SSEPosPost.out and LC(x)_SSENeg_Post.out where (x) is the load case number as.Based on a yield strength of 1.5Sm, the maximum elastic strain where [ for [] is:E ]Anything above this is considered plastic. All plots are based on the SSENeg run as it was judged to be worstcase. Figure 6-5 and Figure 6-6 show strain contours for the applied loads with a multiplier of 1.0, with gray areasindication strain above [ ] .Figure 6-9 shows stress contours for the applied loads with a multiplierof 1.0, where the maximum stress is 34.95 ksi as calculated above. Figure 6-7 and Figure 6-8 show strain contoursfor the applied loads with a multiplier of 1.5. Figure 6-10 shows stress contours for the applied loads with amultiplier of 1.5. For loads with a multiplier of 1.0, the plastic portions of the remnant nozzle are near the edge ofthe window and along the crevice where the remnant nozzle is attached to the J-groove weld with no collapsemechanism formed as shown in Figure 6-5 and Figure 6-6. The plastic portions expands through a majority of thenozzle and weld at a multiplier of 1.5, as shown in Figure 6-7 and Figure 6-8, however a collapse mechanism hasstill not formed completely through the nozzle and weld. Per NB-3228.1 (Reference [1]), the model should be runEnclosure Attachment 6 Page 19 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity.Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)until collapse and the loadings should not exceed 2/3 of the collapse load. Since the model does not collapse at 1.5times all primary loads as shown by ANSYS convergence, it is concluded that a sufficient portion of the remnantnozzle and J-groove weld remains stable up to 1.5 times all primary loads, the nozzle will remain structurallyintact through normal operation.Figure 6-5: Strain Results at I x Primary Loads (Remnant Nozzle and Weld)Enclosure Attachment 6Page 20 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-6: Strain Results at I x Primary Loads (Remnant Nozzle Only)Enclosure Attachment 6Page 21 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-7: Strain Results at 1.5 x Primary Loads (Remnant Nozzle and Weld)Enclosure Attachment 6Page 22 AAREVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-8: Strain Results at 1.5 x Primary Loads (Remnant Nozzle Only)Enclosure Attachment 6Page 23 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-9: Stress Results at I x Primary Loads (Remnant Nozzle and Weld)Enclosure Attachment 6Page 24 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure 6-10: Stress Results at 1.5 x Primary Loads (Remnant Nozzle and Weld)

7.0 CONCLUSION

As found in Section 6.2, the remnant nozzle's lowest natural frequency is much higher than the vortex sheddingfrequency near nozzle #3. Excitation by other primary dynamic loads is also evaluated. There is no excitation ofthe nozzle due to the vortex sheading or other dynamic loads.As discussed in Section 6.3, the Limit Load Analysis per NB-3228.1 as performed through the finite elementanalysis with ANSYS indicates that the lower bound collapse has not been reached even with a factor of 2 beingapplied to the internal pressure and all primary nozzle loads. It is concluded that the remnant nozzle with a flawedregion as analyzed herein remains its structural integrity through the plant nonnal operation.Enclosure Attachment 6Page 25 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)

8.0 REFERENCES

References identified with an (*) are maintained within Palo Verde Nuclear Generating Station Records Systemand are not retrievable from AREVA Records Management. These are acceptable references per AREVAAdministrative Procedure 0402-01, Attachment 8. See page 2 for Project Manager Approval of customerreferences.I. ASME B&PV Code, Section 11I, "Rules for Construction of Nuclear Facility Components," Division 1,1998 Edition, including Addenda through 2000.2. AREVA Inc. Document 32-9215084-001, "ASME Section III End of Life Analysis of PVNGS3 RV BMINozzle Repair."3. *Palo Verde Unit 3 U3R17, Reactor Vessel Bottom Mounted Instrumentation ID Examinations, WesdyneReport WDI-PJF- 1312161 -FSR-00 1, Rev. 0, October 2013.4. AREVA Inc. Design Specification 08-9212780-001, "Palo Verde Unit 3 Reactor Vessel Bottom MountedInstrument Nozzle Modification."5. ASME B&PV Code, Section III, "Nuclear Power Plant Components," Division 1, 1971 Edition includingAddenda through Winter 1973.6. ASME B&PV Code, Section II, Part D, Materials, "Properties," 1998 Edition, including Addenda through2000.7. *APS Report N001-0301-00214, Revision 7, "Reactor Vessel., Unit 3, Analytical Report, V-CE-30869,30AU84."8. *APS Specification MN742-A00179, Revision 4, "Project Specification for a Reactor Vessel Assemblyfor Arizona Nuclear Power Project Units 1, 2, and 3."9. ANSYS and ANSYS Workbench, Release 14.5.7, ANSYS Inc., Canonsburg, Pa.10. ANSYS, Release 14.0, ANSYS Inc., Canonsburg, Pa.11. AREVA Inc. Document 51-9213061-001, "Corrosion Evaluation for Palo Verde Unit 3 Reactor VesselBottom Mounted Instrument Nozzle Modification."Enclosure Attachment 6Page 26 AAREVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)APPENDIX A: NOZZLE CRACKED REGIONA.1 PurposeNon-destructive examination (NDE) of the Palo Verde Unit 3 bottom mounted instrumentation (BMI) nozzle #3by ultrasonic inspection (UT) revealed ten flaw indications in the nozzle in the vicinity of the partial penetrationJ-groove weld that attaches the nozzle to the reactor vessel bottom head. The purpose of this appendix is to definea rectangular window, or cutout, to represent a region of potentially degraded material due to future extension ofcracks in the nozzle. This is used to evaluate the remaining structural integrity and natural frequency of thedegraded nozzle.A.2 Definition of Flaw Indications and Calculation of Nozzle CutoutThe NDE inspection report (Reference [3]) describes ten part-through wall flaw indications in BMI nozzle #3located on the outside surface of the nozzle near the J-groove weld. Flaw indications I through 4 are orientedprimarily in the axial direction (with respect to the nozzle) while flaw indications 5 through 10 are slightlyskewed. It is postulated that over time the "axial" flaws and the skewed flaws will increase in depth and lengthuntil they link up to form a region of degraded material that will potentially affect the structural integrity of thenozzle. To account for this degraded region in the structural models, a volumetric section of the nozzle will beremoved, or cutout, to form a window in the nozzle wall. Using data from the UT inspection report (Reference[3]) to define the initial flaw orientations, the size of the nozzle cutout and its location are calculated by extendingthe defined flaws indications until they intersect.Table A-1 and Table A-2 are taken from the UT inspection report (Reference [3]). Table A-I presents theinspection data for flaw indications I through 4 and Table A-2 provides similar data for flaw indications 5through 10. Each flaw indication is defined by linear (LI/L2) and angular ( l/42) positions of its two end pointsrelative to horizontal and vertical datum lines. The vertical position of the weld at the location of the flawindication is defined by the linear dimensions L3 and L4. The reference positions for these parameters areexplained below, with the aid of Figure A- 1.Distance is measured in inches.Angular position is measured in degrees.Horizontal datum: [Azimuthal datum: [Enclosure Attachment 6Page A-1 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Figure A-I: Reference Positions for UT Inspection DataThe UT data in Table A-I and Table A-2 are rearranged and processed in Table A-3 and Table A-4 to determinebounding flaw characteristics. This data is further processed by "rolling out" the outer surface geometry onto aflat plane to produce linear arc lengths (ArcLen 1/ArcLen2) to the end positions of each flaw indication. Theseflaw indications are then extended upward and downward to determine where the skewed flaws intersect the axialflaws, using the ANSYS (Reference [10]) computer code as a graphical interpreter. The ANSYS input is echoedin the output file (Flaws.out) and creates the output file (Flaws.output). Both are included in the list of computerfiles that have been placed on the ColdStor server (see Section 5.2). The input file takes linear dimensions fromTable A-3 and Table A-4 to draw lines between the end points of each flaw indication and then extends theskewed flaws until they intersect the extended axial flaws. The end points of the extended flaws, obtained fromthe ANSYS output file, are passed to the EXCEL spreadsheet "Flaw Indications.xlsx", where they are used todetermine the size and position of the cracked region, as shown in Table A-4.Enclosure Attachment 6Page A-2 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table A-I: UT Data for Flaw Indications 1 through 4Enclosure Attachment 6 Page A-3Enclosure Attachment 6Page A-3 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table A-2: UT Data for Flaw Indications 5 through 10Enclosure Attachment 6Page A-4 AAR EVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table A-3: Calculation of Nozzle Cutout (1)Enclosure Attachment 6Enclosure Attachment 6 Page A-5mPage A-5 AAR EVA Document No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)Table A-4: Calculation of Nozzle Cutout (2)Enclosure Attachment 6Page A-6 AAREVADocument No. 32-9220624-000Natural Frequency and Structural Integrity Analysis for PVNGS3 RV BMI Nozzle Repair (Non-Proprietary)A.3 Summary of Nozzle CutoutThe nozzle cutout is defined pictorially in Figure A-2. From Table A-4, the overall size of the window is[ ] wide by [ ] high. The window starts at [ ] above the horizontal datum and stops at] below the datum line.Figure A-2: Nozzle Cracked RegionEnclosure Attachment 6Page A-7}}

Retrieved from "https://kanterella.com/w/index.php?title=ML14149A407&oldid=726287"