ML12313A204

Nine Mile Point, Unit 2, Attachment 2, Final Steam Dryer Stress Report, Continuum Dynamics, Incorporated Report No. 12-18NP, Attachment 3, Affidavit from CDI

ML12313A204
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Site:	Nine Mile Point
Issue date:	10/26/2012
From:	Boschitsch A H Continuum Dynamics
To:	Office of Nuclear Reactor Regulation
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TAC ME1476 CDI Report No. 12-18NP
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ATTACHMENT 2FINAL STEAM DRYER STRESS REPORTCONTINUUM DYNAMICS, INCORPORATED REPORT NO. 12-18NP(NON-PROPRIETARY)Certain information, considered proprietary by Continuum Dynamics, Inc., has been deleted from thedocument in this Attachment. The deletions are identified by double square brackets ([[ ]]).Nine Mile Point Nuclear Station, LLCOctober 26, 2012 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationCDI Report No. 12-18NPStress Evaluation of Nine Mile Point Unit 2 Steam Dryerat 115% CLTPRevision 0Prepared byContinuum Dynamics, Inc.34 Lexington AvenueEwing, NJ 08618Prepared under Purchase Order No. 4500428093 forWestinghouse Electric Company LLC1000 Westinghouse DriveCranberry Township, PA 16066Prepared byAlexander H. BoschitschApproved byAlan J. BilaninOctober 2012This report complies with Continuum Dynamics, Inc. Nuclear Quality Assurance Programcurrently in effect.

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationExecutive SummaryThe stresses resulting from acoustic loads at the 115% CLTP operating condition (alsoreferred to herein as the extended power uprate or EPU condition) are calculated for the NineMile Point Unit 2 (NMP2) steam dryer using a finite element model and frequency-basedanalysis methodology. The finite element model of the steam dryer is identical to the onepreviously described in [1] and incorporates the modifications [1, 2] to the steam dryerpreviously deemed necessary to meet an alternating stress ratio SR-a>2 at EPU. Like theacoustic load analysis, the stress calculation is carried out in the frequency domain using theharmonic methodology described in Section 2. The stress analysis is consistent with thosecarried out in the U.S. for prior dryer qualification to EPU conditions. The resulting stresses areassessed for compliance with the ASME B&PV Code 2007 [3],Section III, subsection NG, forthe load combination corresponding to normal operation (the Level A Service Condition).The acoustic loads are prepared using the acoustic circuit model (ACM) version 4.1 [4]. Thismost recent version reflects biases and uncertainties obtained during re-benchmarking againstavailable Quad Cities (QC) data carried out under the requirement that identical filteringmethods be used on both QC data and new plant signal measurements. The ACM acoustic loadpredictions are obtained using main steam line strain gage measurements acquired at 115%CLTP conditions [5]. Other than the removal of known non-acoustic discrete frequencies (e.g.,electrical noise at multiples of 60 Hz) and the application of coherence filtering (which was alsoinvoked when processing the QC data) no other filtering methods are used. Further details of theacoustic load processing procedure are given in [4].It is required that the alternating stress ratios at EPU be above a target level of 2.0. In orderto meet this target, modifications to the dryer detailed in Section 5 of [1] and also in [6], wereimplemented. The modifications fall into the following groups:(1) Welds connecting the lifting rod braces to the vane bank side plates. These locationsexperienced high stress before modification that were addressed by a combination oflocalized reinforcement plates (the two upper-most braces) and increased weld size(lower-most brace).(2) Welds lying on the inward edge of the middle hood reinforcement strip. A 1/8th inchthick reinforcement plate has been added onto the portion of the middle hood lyingoutboard of the closure plate.(3) Inner hood/hood support welds. A total of four 15 lb masses were placed on thecentermost inner hoods.(4) Miscellaneous locations at: (i) the bottoms of the drain channels, (ii) ends of tie barsand (iii) the hood/hood support/base plate junctions which were predicted to havealternating stress ratios slightly below 2.0 at EPU before modifications were installed.(5) Closure plate attachment welds that experienced high stresses due to vibration of theclosure plate. These stresses were alleviated by attaching reinforcement ribs tosuppress the adverse resonant responses.i This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTo obtain refined estimates of the linearized stresses at selected high stress locations(3)]]A stress evaluation of the entire post-reinforcement NMP2 steam dryer shows that at nominalEPU operation (no frequency shift) the minimum alternating stress ratio (SR-a) anywhere on thesteam dryer is SR-a=3.09. The loads used to obtain this value account for all the end-to-endbiases and uncertainties in the loads model [5] and finite element analysis. To account foruncertainties in the modal frequency predictions of the finite element model, the stresses are alsocomputed for loads that are shifted in the frequency domain by +/-2.5%, +/-5%, +7.5% and +/-10%.The minimum alternating stress ratio encountered at any frequency shift is found to beSR-a=2.49 occurring at the +7.5% shift and occurring on the inner vane bank welded endplate/side plate junction. The stress ratio due to maximum stresses (SR-P) is dominated by staticloads and is SR-P=1.25 with all frequency shifts considered.The assessment shows that with the modifications in place the NMP2 steam dryer meets therequired stress margin at EPU operation.During power ascension testing NMP identified two off-normal loading conditions associatedwith the operational lineup of the RCIC system. Therefore additional stress evaluation isperformed using both estimated and measured loads obtained with the RCIC line isolated at theEPU condition. The resulting limiting alternating stress ratio is shown to be SR-a=2.05 so thatthe target stress margin is maintained.ii This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable of ContentsSection PageExecutive Summary ................................................................................................................. iTable of Contents .................................................................................................................. iii1. Introduction and Purpose ........................................................................................................ 12. Methodology & Evaluation Procedures ................................................................................ 52 .1 O v erv iew ............................................................................................................................... 52 .2 ....................................................... (3) ........................................................... 72.3 Computational Considerations .......................................................................................... 82 .4 ........................................ (3 ) ....................................................................... ..102.5 Flaw Evaluation ................................................ 113. Finite Element Model Description ....................................................................................... 193.1 Steam Dryer Geometry ............................................ 193.2 Material Properties ......................................................................................................... 223.3 Model Simplifications ................................................................................................... 223.4 Perforated Plate Model .................................................................................................. 233.5 Vane Bank Model .......................................................................................................... 253.6 Water Inertia Effect on Submerged Panels .................................................................... 263.7 Structural Damping ........................................................................................................ 263.8 Mesh Details and Element Types ................................................................................... 263.9 Connections between Structural Components .............................................................. 263.10 P ressure L oading ..................................................................... ......................................... 384. Structural A naly sis .................................................................................................................... 4 14 .1 S tatic A nalysis .................................................................................................................... 4 14.2 Harmonic Analysis .......................................... ......... 414.3 Post-Processing .......................................... ....................... 474.4 Computation of Stress Ratios for Structural Assessment ........... ........... 474 .5 ........................................ (3) ..................................... .............................. ..505. Modifications Implemented to Meet EPU Stress Margins ................................................... 525.1 Lifting Rod Support Brackets (Group 1) .............................................................. ............. 525.2 Middle Hood/Reinforcement Strip (Group 2) ................................................................ 595.3 Inner Hoods/Hood Support (Group 3)........................................................................... 615.4 Group 4 Locations ........................................................................................................ 645.5 Group 5 Locations -Modification of Closure Plates ................................................... 655.6 Summary of Modifications ............................................................................................ 705.7 Final (As-Built) Modifications and Installation ............................................................. 716 .R esu lts .......................................................................................................................................766.1 General Stress Distribution and High Stress Locations ................................................. 776.2 Load Combinations and Allowable Stress Intensities ................................................... 866.3 Frequency Content and Filtering of the Stress Signals ..................................................... 1056.4 Real Time Analysis With (i) 92.5 Hz signal Included and (ii) RCIC Line Closed ......... 1157 .C on clu sions ............................................................................................................................. 12 18. R eferences ............................................................................................................................... 122111.° This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information1. Introduction and PurposeCurrent licensing procedures to qualify the Nine Mile Point Unit 2 (NMP2) nuclear plant foroperation at Extended Power Uprate (EPU) operating condition require a stress assessment of thesteam dryer to ensure adequate stress margins under the increased loads. The steam dryer loadsdue to acoustic pressure fluctuations in the main steam lines (MSLs) are potentially damagingand the cyclic stresses from these loads can produce fatigue cracking if loads are sufficientlyhigh. The industry has addressed this problem with physical modifications to the dryers, as wellas a program to define steam dryer loads and their resulting stresses. The EPU qualificationprocess includes stress evaluations using both current licensed thermal power (CLTP) and EPUacoustic loads. The CLTP loads are acquired first and, by appropriate scaling, used to estimateEPU loads before power ascension takes place. A stress evaluation is carried out for these scaledloads to establish adequate stress margin and, if required, to design dryer modification to meetthese margins. Details of these CLTP-based stress evaluations are documented in [1]. Since themethods for estimating EPU loads from ones measured at CLTP are subject to inherentconservatisms and approximations a confirmatory stress calculation is also required that usesactual loads measured at EPU conditions. The present report documents this confirmatory stressevaluation for the NMP2 steam dryer by calculating the maximum and alternating stressesgenerated using strain gage MSL pressure measurements acquired at EPU operation asdocumented in [5] (data file name: 20120721142636).The load combination considered here corresponds to normal operation (the Level A ServiceCondition) and includes fluctuating pressure loads developed from NMP2 main steam line data,and weight. The fluctuating pressure loads, induced by the flowing steam, are predicted using aseparate acoustic circuit analysis of the steam dome and main steam lines [8]. Level B serviceconditions, which include seismic loads, are not included in this evaluation. Stress ratios areobtained by comparing these stresses (appropriately adjusted at welds) against allowable valuesand used to ensure compliance with the ASME Code (ASME B&PV Code,Section III,subsection NG) and to confirm that the alternating stress ratio, SR-a>2, as required under currentlicensing requirements.The current stress evaluation of the NMP2 steam dryer is performed using acoustic loadsgenerated using a revised Acoustic Circuit Model (ACM) Rev. 4.1 [4]. The development of thisrevision was motivated primarily by a requirement for. consistent usage of noise filteringstrategies during both model calibration against available data and application of the model toplants. Other than the removal of known non-acoustic discrete frequencies (e.g., electrical noiseat multiples of 60 Hz) and the application of coherence filtering (which was also invoked whenprocessing the Quad Cities data) no other filtering methods are used. In particular, no noisesubtraction using low power data is performed. Further details of the ACM Rev. 4.1 calibrationactivity are provided in [4]. Its application to obtain NMP2 steam dryer acoustic loads isdetailed in [5]. As described in [4] re-benchmarking the ACM against available Quad Cities dataproduced updated estimates of the acoustic speed and damping in the acoustics description andalso revised biases and uncertainties due to changes in the model, coherence-based noise filteringand comparison method. The biases and uncertainties used for the present load estimates arebased on the comparison with QC data at 790MWe using 16 sensors.1 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationThe stress analysis is carried out in the frequency domain, which confers a number of usefulcomputational advantages over a time-accurate transient analysis including the ability to assessthe effects of frequency scaling in the loads without the need for additional finite elementcalculations. The analysis develops a series of unit stress solutions corresponding to theapplication of a unit pressure at a MSL at specified frequency, f. Each unit solution is obtainedby first calculating the associated acoustic pressure field using a separate analysis that solves thedamped Helmholtz equation within the steam dryer [9]. This pressure field is then applied to afinite element structural model of the steam dryer and the harmonic stress response at frequency,f, is calculated using the commercial ANSYS 10.0 finite element analysis software. This stressresponse constitutes the unit solution and is stored as a file for subsequent processing. Once allunit solutions have been computed, the stress response for any combination of MSL pressurespectrums (obtained by Fast Fourier Transform of the pressure histories in the MSLs) isdetermined by a simple matrix multiplication of these spectrums with the unit solutions. Detailsof the frequency-based stress evaluation methodology are contained inIn order to qualify the NMP2 steam dryer for EPU operation it is required that the limitingalternating stress ratio at EPU be above a target level of 2.0. In previous stress evaluations [10]it was determined that when the estimated EPU acoustic loads were impressed on the originalsteam dryer configuration, the predicted alternating stress ratios at several locations fell belowthe target level. Therefore, modifications to the steam dryer have been implemented to ensurethat all locations meet or exceed the target stress ratio. Briefly, the groups and associatedmodifications consist of the following:Group 1: The lifting rod bracket/side plate welds. High membrane stresses werepredicted on the end of the existing weld. For the upper and middle bracketsthe modification to alleviate these stresses consists of reinforcements plateswelded to the vane bank side plate and brace. For the lower-most brackets asimple increase in the weld size from 11/4" to V2" suffices to reduce the stress toacceptable levels.Group 2: The middle hood reinforcement strip that previously experienced a high stressdue to vibration of the outboard section of the middle hood. This stress hasbeen alleviated by overlaying a 1/8" curved plate over the portion of themiddle hood located between the existing reinforcement strip and the closureplate.Group 3: The inner hood/hood support welds that were previously subject to highstresses resulting from the inner hood vibrations. To reduce these stresses atotal of four 15 lb masses are placed on the central inner hood panels (the twopanels connecting to the central hood support) 18" below the top of the vanebank surface.Group 4: A collection of locations that were previously determined to be slightly underthe target stress ratios. These locations included:(a) Middle hood/hood support welds. These stress locations are similar to theones on the inner hood/hood support welds and are alleviated in a similarmanner by adding a total of four 10 lb masses to the central sections of themiddle hoods.2 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information(b) Bottoms of the drain channel/skirt welds. These welds have beenreinforced by thickening the length and wrapping the weld around the junctionterminus and continuing it for 1" along the interior side.(c) Outer hood/hood support/cover plate junctions. A stress relief cut-outhole optimized to minimize the alternating stresses has been added to thesupport plate.Group 5: The closure plate attachment welds that, in the original configuration,encountered high stresses due to a strong 128 Hz vibration of the closureplate. These stresses have been addressed by attaching reinforcement ribs tosuppress and increase the frequency of the adverse resonant response.These modifications are fully accounted for in the current stress evaluation by updating theunit solutions of the complete dryer over the 30-250 Hz frequency range including the stiffenedclosure plate, the masses added to the inner and middle hoods, and the 1/8" thick reinforcementplate placed over the middle hood section outboard of the closure plate. Below 30 Hz theoriginal un-modified steam dryer unit solutions are used. This is acceptable since the dynamicresponse of the dryer below this frequency is small; it is also conservative since no credit is takenfor the stress reductions realized by these modifications. Other reinforcements such as themodified channel/skirt weld are localized (3)The frequency-based harmonic stress evaluation methodology, finite element model andpost-processing procedures ((3)) arefully identical to those described in the previous NMP2 steam dryer stress evaluation usingCLTP loads scaled to EPU conditions [1] and are described in Sections 2-4. The modificationsmade to the dryer are described in Section 5. The present stress report is distinguished fromprevious ones in that the acoustic signals are obtained at actual EPU conditions rather thaninferred from CLTP measurements. The results in terms of stress intensity distributions andstress ratios together with PSDs of the dominant stress components are given in Section 6.This stress evaluation shows that the limiting alternating stress ratio on the dryer at EPU isSR-a=2.49. The limiting peak stress ratio due to maximum membrane and bending stressesincluding static contributions is SR-P=1.25. These values show that the present modified steamdryer meets the required stress margin at EPU operation.3 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationDuring power ascension testing NMP identified two off-normal loading conditions associatedwith the operational lineup of the reactor core isolation cooling (RCIC) system that create eithera 92.5 Hz or 89.25 Hz content on the MSL B line. To predict the stresses resulting from thisload real time analyses were performed using both estimated and measured EPU loads obtainedfrom the test data. These calculations (Section 6.4) show that the limiting alternating stress ratiois SR-a--2.05 thus confirming that the required stress margin is sustained.4 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information2. Methodology & Evaluation Procedures2.1 OverviewBased on previous analysis undertaken at Quad Cities Units 1 and 2, the steam dryer canexperience strong acoustic loads due to the fluctuating pressures in the MSLs connected to thesteam dome containing the dryer. C.D.I. has developed an acoustic circuit model (ACM) that,given a collection of strain gage measurements of the fluctuating pressures in the MSLs, predictsthe acoustic pressure field anywhere inside the steam dome and on the steam dryer [4, 8, 9, 11 ].The ACM is formulated in frequency space and contains two major components that are directlyrelevant to the ensuing stress analysis of concern here. (3)5 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information11(3)]]6 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information(3)]](3)]]7 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information(3)]]2.3 Computational ConsiderationsFocusing on the structural computational aspects of the overall approach, there are a numberof numerical and computational considerations requiring attention. The first concerns thetransfer of the acoustic forces onto the structure, particularly the spatial and frequencyresolutions. The ANSYS finite element program inputs general distributed pressure differencesusing a table format. This consists of regular 3D rectangular (i.e., block) nxxnyxnz mesh wheren. is the number of mesh points in the i-th Cartesian direction and the pressure difference isprovided at each mesh point (see Section 3.10). These tables are generated separately using aprogram that reads the loads provided from the ACM software, distributes these loads onto thefinite element mesh using a combination of interpolation procedures on the surface and simplediffusion schemes off the surface (off-surface loads are required by ANSYS to ensure properinterpolation of forces), and written to ASCII files for input to ANSYS. A separate load file iswritten at each frequency for the real and imaginary component of the complex force.The acoustic field is stored at 5 Hz intervals from 0 to 250 Hz. While a 5 Hz resolution issufficient to capture frequency dependence of the acoustic field (i.e., the pressure at a pointvaries gradually with frequency), it is too coarse for representing the structural responseespecially at low frequencies. For 1% critical structural damping, one can show that thefrequency spacing needed to resolve a damped resonant peak at natural frequency, fn, to within5% accuracy is Af=0.0064xfn. Thus for fn=10 Hz where the lowest structural response modesoccur, a frequency interval of 0.064 Hz or less is required. In our calculations we require that'5% maximum error be maintained over the range from fn=5 Hz to 250 Hz resulting in a finestfrequency interval of 0.0321 Hz at the low frequency end (this adequately resolves all structuralmodes up to 250 Hz). Since there are no structural modes between 0 to 5 Hz, a 0.5 Hz spacing isused over this range with minimal (less than 5%) error. The unit load, fn(-oR), at anyfrequency, cOk, is obtained by linear interpolation of the acoustic solutions at the two nearestfrequencies, coi and coi+1, spaced 5 Hz apart. Linear interpolation is sufficient since the pressureload varies slowly over the 5 Hz range (linear interpolation of the structural response would notbe acceptable over this range since it varies much more rapidly over the same interval). Detailsregarding the frequency resolution have been provided in [13].Solution Management(3)]]8 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information(3)]]Structural DampingIn harmonic analysis one has a broader selection of damping models than in transientsimulations. A damping factor, z, of 1% critical damping is used in the structural analysis. Intransient simulations, this damping can only be enforced exactly at two frequencies (where thedamping model is "pinned"). Between these two frequencies the damping factor can byconsiderably smaller, for example 0.5% or less depending on the pinning frequencies. Outsidethe pinning frequencies, damping is higher. With harmonic analysis it is straightforward toenforce very close to 1% damping over the entire frequency range. In this damping model, thedamping matrix, D, is set toD=2zK (7)cowhere K is the stiffness matrix and 0o the forcing frequency. When comparing the responseobtained with this model against that for a constant damping ratio, the maximum difference atany frequency is less than 0.5%, which is far smaller than the 100% or higher response variationobtained when using the pinned model required in transient simulation.Load Frequency-RescalingOne way to evaluate the sensitivity of the stress results to approximations in the structuralmodeling and applied loads is to rescale the frequency content of the applied loads. In thisprocedure the nominal frequencies, 03k, are shifted to (l+X)(0k, where the frequency shift, X,ranges between +/-10%, and the response recomputed for the shifted loads. The objective of thefrequency shifting can be explained by way of example. Suppose that in the actual dryer a strongstructural-acoustic coupling exists at a particular frequency, (0*. This means that the followingconditions hold simultaneously: (i) the acoustic signal contains a significant signal at co*; (ii) thestructural model contains a resonant mode of natural frequency, (On, that is near or*; and (iii) theassociated structural mode shape is strongly coupled to the acoustic load (i.e., integrating theproduct of the mode shape and the surface pressure over the steam dryer surface produces asignificant modal force). Suppose now that because of discretization errors and modelingidealizations that the predicted resonance frequency differs from co* by a small amount (e.g.,1.5%). Then condition (ii) will be violated and the response amplitude therefore significantlydiminished. By shifting the load frequencies one re-establishes condition (ii) when (1+ X)o)* is9 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationnear (On. The other two requirements also hold and a strong structural acoustic interaction isrestored.(3)]]Evaluation of Maximum and Alternating Stress IntensitiesOnce the unit solutions have been obtained, the most intensive computational steps in thegeneration of stress intensities are: (i) the FFTs to evaluate stress time histories from (5); and(ii) the calculation of alternating stress intensities. (3)The high computational penalty incurred in calculating the alternating stress intensities is dueto the fact that this calculation involves comparing the stress tensors at every pair of points in thestress history. This comparison is necessary. since in general the principal stress directions canvary during the response, thus for N samples in the stress history, there will be (N-1)N/2 suchpairs or, for N=64K (the number required to accurately resolve the spectrum up to 250 Hz in0.01 Hz intervals), 2.1 x 109 calculations per node each requiring the determination of the roots toa cubic polynomial. (3)2.4(3)11(3)10 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information(3)]]2.5 Flaw EvaluationAs part of the steam dryer stress assessment for EPU operation an evaluation of existingflaws discovered in the outer hood/hood support/base plate junctions is required to establishwhether or not flaw propagation will occur at EPU conditions. If growth of the existingindications cannot be readily ruled out then a modification to the existing locations is required.Performing the flaw evaluation and designing the stress relief cutout required the combined useof several analysis methods which are summarized here. The flaw growth assessment is11 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationperformed jointly by CDI and Structural Integrity Associates (SIA). CDI provided a highresolution sub-model that includes details. of the local welds together with the perimeter loadsand inertial and body forces as described above. CDI also conducted supporting calculations toestimate the RMS stresses and determine whether the behavior at these locations is symptomaticof load- or displacement-controlled stresses. Finally a modified sub-model of this location witha circular cutout in the hood support was developed as a contingency repair in the event thatarresting of further crack growth at EPU operation cannot be assured under the current(unmodified) configuration. The sizing and placement of the circular cut-out is described in [7]and(3). With these results, SIA conducted the flaw evaluation using acombination of analytical methods and finite element modeling using crack elements asdescribed in [16].Load- or Displacement-Controlled StressesThe detailed flaw evaluation requires an assessment of whether the stress at the crack isprimarily load- or displacement-controlled as this distinction warrants different criteria forestablishing crack growth. In a load-controlled configuration the applied load essentiallyremains constant as the structure displaces. In a displacement-controlted configuration the forcesexperienced by the load are relieved as the structure displaces.The distinction can be explained by way of example and reference to Figure 1 which depictsa structure similar to the hood support. The structure contains a flaw as shown and the righthand edge is either: (i) loaded with a constant force or (ii) required to move by a specifieddisplacement. The former case would arise if the edge is directly loaded; the second situationarises when the hood response is dominated by the response of adjacent structures. Suppose thatthe displacement at the location indicated is monitored as the flaw length is increased. In a load-controlled configuration -case (i) -the monitored displacement is expected to increase as theflaw grows. Conversely in the displacement-controlled setting the monitored displacement willonly be weakly affected by the flaw length and will either remain approximately the same ordecrease with increasing flaw size.For the outer hood/hood support/cover plate junction it is noted that the 1/4" outer hoodsupport connects to the much thicker (1/2") outer hoods on the left edge and to the massive outervane banks on the right edge. Since the outer hoods connect directly to the vane banks it can besurmised that acoustic forcing of the outer hoods will produce motions in the combined outerhood + vane bank assembly. Because of the comparatively stiff outer hoods and massive vanebanks (compared to the hood support), the motions of this assembly is anticipated to be onlyweakly affected by a flaw at this junction.To verify this behavior for a complex structure such as the dryer where multiple load pathsexist, a practical means of establishing whether the forces transmitted to the hood support platesare displacement-limited is required. To this end the global finite element model is used andelements along the hood/hood support weld line progressively disconnected to simulate flaws ofdifferent lengths. Thus one begins with the fully connected model and evaluates thedisplacements at selected locations on the hood support and connected components whensubjected to the ACM Rev. 4.1 acoustic loads. These locations are chosen to lie between 3-912 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationinches away from the high stress location as shown in Figure 2. The lowest finite element in thehood support that is adjacent to the outer hood/hood support weld is then disconnected. Thenearest middle hood/hood support is similarly disconnected and the displacements at the samelocations recalculated. Next this process is repeated by disconnecting the two lowest finiteelements along the weld (i.e., the one. disconnected previously and the one immediately above italso adjacent to the weld) and re-evaluating the displacements; then disconnecting the threelowest elements, etc. The displacements are then plotted as a function of disconnection length tosee whether the displacements generally increase with disconnection length which is indicativeof load-controlled behavior, or whether the displacements remain constant or reduce withdisconnection length which implies displacement-controlled response. These plots are presentedin Figure 3. From these plots the response at the outer hood/hood support/cover plate isconsistent with displacement-controlled behavior as all displacements tend to reduce with cracklength or plateau to constant values.At the middle hood/hood support/base plate junction, the displacement amplitudes alldecrease gradually or plateau except for the middle hoods themselves whose amplitudes continueto grow. This is indicative of a vibration mode that continues to grow as the restraint providedby the hood support is reduced. For the hood support itself however, where the dominant stressoccur, the displacements at 2A and 2B are generally level or diminishing with crack length (seeFigure 3) indicating that the hood support stress is also displacement-controlled.The stress at the flaw tip is also recorded as a function of crack length to corroborate whetheror not the stress is displacement-controlled. Generally, one would expect to observe a reductionin this stress as the crack is extended. This observation is indeed borne out as shown in Figure 4.This plot records the maximum unit solution stress at the flaw tip as a function of displacementlength where the maximum is taken over all frequencies and MSL forcings.Finally, it is noted that the displacement-controlled stress behavior at all hood/hoodsupport/base plate junctions is supported by field observations at explained at length in [16].Essentially, for a load-controlled stress state the observed flaws Would have grown toconsiderably longer lengths. Instead, the flaws which are believed to have been initiated byresidual stresses, have grown to approximately 2" on the outer hood supports and 0.5" at themiddle and some inner hood supports and stopped. This is fully consistent with a displacement-controlled stress situation and also corroborates the analysis conducted in [16] which predictscrack growth to approximately 2" during the first operational cycle and subsequent arrest of thecrack as the crack tip stress field diminishes. While the evaluation in [16] focuses on the outerhood support, this evaluation constitutes the bounding flaw assessment for all (outer, middle andinner) hood support junctions given that the highest junction stresses occur on the outer hoodsupports and all locations evidence displacement-controlled stress behavior near the flaws.13 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFlaw evaluatedatdifferentlengths %Displacement, u.f,"Appiled WKad ForBaunduy DispiaemeMFigure 1. Conceptual arrangement of hood support geometry for the determining whether thelimiting stresses are load- or displacement-controlled.14 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 2. Depiction from below of locations near the outer hood/hood support/cover plate highstress point where displacements are recorded. Location 0 lies at the high stress location.Location 1 lies on the bottom edge of the hood support whereas locations 2A and 2B lieapproximately 9" and 13" respectively above location 1. Locations 3A and 3B reside on theouter hood at approximately the same heights as 2A and 2B; Locations 4A and 4B are similarlyplaced on the outer hood and are located behind the hood support and thus obscured by the hoodsupport in this view. Finally locations 5 and 6 are on the outer cover plate. Precise values aregiven in Table 1. Analogous locations are erected about the middle hood/hood support junction.Table 1. Coordinates of Locations 0-6 in Figure 2.Index node x y z0 95267 -102.75 28.39 01 14954 -94.875 28.39 02A 14789 -93.7966 28.39 10.05582B 14840 -93.7159 28.39 13.69983A 79184 -102.624 23.9483 9.448253B 78999 -102.495 23.689 13.41624A 77836 -102.617 33.8335 9.701844B 77835 -102.48 34.3628 13.81475 48374 -105.543 24.76 06 48388 -106.358 32.0303 015 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information4.50E-03 ,4.OOE-03 +-Cz-a1ECa.3.50E-033.OOE-032.50E-032 .GOE-03aI- -- ---- --- ----1.50E-03 -C ~ 3A----2A2 B3AB--4A-4B--5--* 61 .OOE-035.00E-04.111111-1ý....4111O.GOE+O +0I2345No. of Disconnected Elements2.50E-03 Tzt1E4.0CECLW1is2.0OE-03................................ --------1.50E-031.OOE-03 --ik--0--0- 2A"--4ý3A--4--38----*--4A-4B-465.00E-04O.OOEi-OO012345No. of Disconnected ElementsFigure 3. Variation of displacement amplitudes at the locations depicted in Figure 2 as afunction of the number of disconnected elements along the hood/hood support weld line. Top -outer hood; bottom -middle hood.16 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationMaximum Unit Solution Stress Intensity at Hood/HoodSupport Junctions16000140001200010000S0.* 800060004000200000 1 2 3 4 5No. of Disconnected ElementsFigure 4. Variation of the maximum unit solution stress at the tip of the disconnection line as afunction of the number of disconnected elements. The maximum of the stress intensity is takenover all MSL loadings and frequencies.17 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationSizing and Positioning the Stress Relief Cut-Out HoleIf the flaw evaluation shows insufficient margin a means of reducing the stress is needed.The option considered here is the insertion of a semi-circular stress relief cutout hole. The cut-out hole is optimized by adjusting the position and radius of the hole to minimize the overallstress ratio. The optimization process is carried out using a shell-based sub-model to expeditethe overall design process. (3)18 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information3. Finite Element Model DescriptionA description of the ANSYS model of the nine Mile Point Unit 2 steam dryer follows.3.1 Steam Dryer GeometryA geometric representation of the Nine Mile Point Unit 2 steam dryer was developed fromavailable drawings (provided by Constellation Energy Group and included in the design recordfile, DRF-C-279C) within the Workbench module of ANSYS. The completed model is shown inFigure 5. This model includes on-site modifications to the Nine Mile Point Unit 2 steam dryer.These are as follows.On-Site Modifications(i) The top tie rods are replaced with thicker ones.(ii) Inner side plates are replaced with thicker ones.(iii) Middle hoods are reinforced with additional strips.(iv) Lifting rods are reinforced with additional gussets.(v) Per FDDR KG1-0265 the support conditions are adjusted to ensure that the dryeris supported 100% on the seismic blocks.These additional modifications have been incorporated into the NMP2 steam dryer modeland are reflected in the results presented in this report. The affected areas are shown in Figure 6.Modifications Implemented for EPU Operation.In [17] several modifications were proposed to meet target EPU stress margins using aprevious acoustic loads model (ACM Rev. 4.0) without noise subtraction. These modificationsare now superseded here by the ones below and detailed in Section 5 that are obtained by on thebasis of acoustic loads processed using the ACM Rev. 4.1 analysis. These planned modificationsinclude:(vi) Reinforcement strips are added to the closure plates.(vii) Reinforcements to the upper-most and middle lifting rod braces are made in theform of additional strengthening plates.(viii) Increase the attachment weld size of the lower-most lifting rod brace from 1/4" to(ix) A 1/8th in curved plate is placed over the middle hood section lying outboard ofthe closure plate.(x) Four 15 lb masses are added to the central inner hood panels.(xi) Stress relief cut-outs are added to the outer hood/hood support/base platejunctions to alleviate local stresses.(xii) A wrap-around weld is added to the bottom of the drain channel/skirt weld.(xiii) Four 10 lb masses are added to the central middle hood panels.All of the modifications summarized here and detailed in Section 5 are implemented in theresults produced in Section 6.19 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationReference FrameThe spatial coordinates used herein to describe the geometry and identify limiting stresslocations are expressed in a reference frame whose origin is located at the intersection of thesteam dryer centerline and the plane containing the base plates (this plane also contains the top ofthe upper support ring and the bottom edges of the hoods). The y-axis is parallel to the hoods,the x-axis is normal to the hoods pointing from MSL C/D to MSL A/B, and the z-axis is vertical,positive up.\NS 44IA50.00Figure 5. Overall geometry of the Nine Mile Point Unit 2 steam dryer model.20 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 6. Existing on-site modifications accounted for in the model and associated geometricaldetails.21 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information3.2 Material PropertiesThe steam dryer is constructed from Type 304 stainless steel and has an operatingtemperature of 550'F. Properties used in the analysis are summarized below in Table 2.Table 2. Material properties.Young's Modulus -Density Poisson(106 psi) (ibm/in3) Ratiostainless steel 25.55 0.284 0.3structural steel with added water 25.55 0.856 0.3inertia effectThe structural steel modulus is taken from Appendix A of the ASME Code for Type 304Stainless Steel at an operating temperature 550'F. The effective properties of perforated platesand submerged parts are discussed in Sections 3.4 and 3.6. Note that the increased effectivedensity for submerged components is only used in the harmonic analysis. When calculating thestress distribution due to the static dead weight load, the unmodified density of steel(0.284 lbm/in3) is used throughout.Inspections of the NMP Unit 2 dryer have revealed IGSCC cracks in the upper support ring(USR) and skirt. A separate analysis of these cracks [18] has been performed to determinewhether: (i) they will propagate further into the structure and (ii) their influence upon structuralresponse frequencies and modes must be explicitly accounted for. To establish (i) the stresscalculated in the global stress analysis is used in conjunction with the crack geometry tocalculate the stress intensity factor which is then compared to the threshold stress intensity. Forthe USR and skirt cracks the highest stress intensity factors are 1.47 ksi-in05 and 2.75 ksi-in°5respectively; both values are below the threshold value (3 ksi-in°5) implying that fatigue crackgrowth will not occur.To determine (ii) the change in modal response frequencies due to the presence of a flaw ispredicted by analytical means (in the case of the USR) or using finite element analysis (for theskirt). In each case, the flaw size used in these calculations is increased to ensure conservativeestimates (for example, in the case of the skirt flaws extending up to 1/2 the panel width areconsidered). For the USR, the change in modal frequencies due to the presence of the cracks isless than 0.5%. For the skirt, using a conservative estimate for the crack to panel width of 0.3(the measured value is less than 0.17) the change in modal frequency is also less than 0.5%. Inboth cases such small changes in modal frequencies are considered negligible and are readilyaccounted for when performing frequency shifting.3.3 Model SimplificationsThe following simplifications were made to achieve reasonable model size while maintaininggood modeling fidelity for key structural properties:* Perforated plates were approximated as continuous plates using modified elasticproperties designed to match the static and modal behaviors of the perforated plates. The22 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationperforated plate structural modeling is summarized in Section 3.4 and Appendix C of[19].0 The drying vanes were replaced by point masses attached to the corresponding troughbottom plates and vane bank top covers (Figure 8). The bounding perforated plates, vanebank end plates, and vane bank top covers were explicitly modeled (see Section 3.5).9 The added mass properties of the lower part of the skirt below the reactor water levelwere obtained using a separate hydrodynamic analysis (see Section 3.6).(3)]0 Four steam dryer support brackets that are located on the reactor vessel and spaced at 90'intervals were explicitly modeled (see Section 3.9).* Most welds were replaced by node-to-node connections; interconnected parts sharecommon nodes along the welds. In other locations the constraint equations betweennodal degrees of freedom were introduced as described in Section 3.9.3.4 Perforated Plate ModelThe perforated plates were modeled as solid plates with adjusted elastic and dynamicproperties. Properties of the perforated plates were assigned according to the type and size ofperforation. Based on [20], for an equilateral square pattern with given hole size and spacing,the effective moduli of elasticity were found.The adjusted properties for the perforated plates are shown in Table 3 as ratios to materialproperties of structural steel, provided in Table 2. Locations of perforated plates are classifiedby steam entry / exit vane bank side and vertical position.Tests were carried out to verify that this representation of perforated plates by continuousones with modified elastic properties preserves the modal properties of the structure. These testsare summarized in Appendix C of [19]and compare the predicted first modal frequency for acantilevered perforated plate against an experimentally measured value. -The prediction wasobtained for 40% and 13% open area plates (these are representative of the largest and lowestopen area ratios of the perforated plates at NMP2, as seen in Table 3) using the analyticalformula for a cantilevered plate and the modified Young's modulus and Poisson's ratio given byO'Donnell [20]. The measured and predicted frequencies are in close agreement, differing byless than 3%.(3)]]23 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information[((3)]][F(3)]]Figure 7. [[>(3)]]24 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 3. Material properties of perforated plates.(3)]]3.5 Vane Bank ModelThe vane bank assemblies consist of many vertical angled plates that are computationallyexpensive to model explicitly, since a prohibitive number of elements would be required. Theseparts have significant weight which is transmitted through the surrounding structure, so it isimportant to capture their gross inertial properties. Here the vane banks are modeled as acollection. of point masses located at the center of mass for each vane bank section (Figure 4).The following masses were used for the vane bank sections, based on data found on provideddrawings:inner banks, 1618 Ibm, 4.sections per bank;middle banks, 1485 Ibm, total 4 sections per bank; andouter banks, 1550 ibm, 3 sections per bank.These masses were applied to the base plates and vane top covers using the standard ANSYSpoint mass modeling option, element MASS2 1. ANSYS automatically distributes the point massinertial loads to the nodes of the selected structure. The distribution algorithm minimizes thesum of the squares of the nodal inertial forces, while ensuring that the net forces and momentsare conserved. Vane banks are not exposed to main steam lines directly, but rather shielded bythe hoods.The collective stiffness of the vane banks is expected to be small compared to thesurrounding support structure and is neglected in the model. In the static case it is reasonable toexpect that this constitutes a conservative approach, since neglecting the stiffness of the vanebanks implies that the entire weight is transmitted through the adjacent vane bank walls andsupports. In the dynamic case the vane banks exhibit only a weakresponse since (i) they havelarge inertia so that the characteristic acoustically-induced forces divided by the vane massesand inertias yield small amplitude motions, velocities and accelerations; *and (ii) they areshielded from acoustic loads by the hoods, which transfer dynamic loads to the rest of thestructure. Thus, compared to the hoods, less motion is anticipated on the vane banks so that25 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationapproximating their inertial properties with equivalent point masses is justified. Nevertheless,the bounding parts, such as perforated plates, side panels, and top covers, are retained in themodel. Errors associated with the point mass representation of the vane banks are compensatedfor by frequency shifting of the applied loads.3.6 Water Inertia Effect on Submerged PanelsWater inertia was modeled by an increase in density of the submerged structure to accountfor the added hydrodynamic mass. This added mass was found by a separate hydrodynamicanalysis (included in DRF-C-279C supporting this report) to be 0.143 lbm/in2 on the submergedskirt area. This is modeled by effectively increasing the material density for the submergedportions of the skirt. Since the skirt is 0.25 inches thick, the added mass is equivalent to adensity increase by 0.572 lbm/in3.This added water mass was included in the ANSYS model byappropriately modifying the density of the submerged structural elements when computingharmonic response. For the static stresses, the unmodified density of steel is Used throughout.3.7 Structural DampingStructural damping was defined as 1% of critical damping for all frequencies. This dampingis consistent with-guidance given on pg. 10 of NRC RG-1.20 [24].3.8 Mesh Details and Element Types.Shell elements were employed to model the skirt, hoods, perforated plates, side and endplates, trough bottom plates, reinforcements, base plates and cover plates. Specifically, the four-node, Shell Element SHELL63, was selected to model these structural components. Thiselement models bending and membrane stresses, but omits transverse shear. The use of shellelements is appropriate for most of the structure where the characteristic thickness is smallcompared to the other plate dimensions. For thicker structures, such as the upper and lowersupport rings, solid brick elements were used to provide the full 3D stress. The elementsSURF 154 are used to assure proper application of pressure loading to the structure. Mesh detailsand element types are shown in Table 4 and Table 5.The mesh is generated automatically by ANSYS with refinement near edges. The maximumallowable mesh spacing is specified by the user. Here a 2.5 inch maximum allowable spacing isspecified with refinement upto 1.5 inch in the following areas: drain pipes, tie rods, the curvedportions of the drain channels and the hoods. Details of the finite element mesh are shown inFigure 9. Numerical experiments carried out using the ANSYS code applied to simpleanalytically tractable plate structures with dimensions and mesh spacings similar to the ones usedfor the steam dryer, confirm that the natural frequencies are accurately recovered (less than 1%errors for the first modes). These errors are compensated for by theuse of frequency shifting.3.9 Connections between Structural ComponentsMost connections between parts are modeled as node-to-node connections. This is thecorrect manner (i.e., within the finite element framework) of joining elements away fromdiscontinuities. At joints between shells, this approach omits the additional stiffness provided bythe extra weld material. Also, locally 3D effects are more pronounced. The latter effect isaccounted .for using weld factors. The deviation in stiffness due to weld material is negligible,since weld dimensions are on the order of the shell thickness. The consequences upon modal26 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationfrequencies and amplitude are, to first order, proportional to t/L where t is the thickness and L acharacteristic shell length. The errors committed by ignoring additional weld stiffness are thussmall and readily compensated for by performing frequency shifts.When joining shell and solid elements, however, the problem arises of properly constrainingthe rotations, since shell element nodes contain both displacement and rotational degrees offreedom at every node whereas solid elements model only the translations. A node-to-nodeconnection would effectively appear to the shell element as a simply supported, rather than (thecorrect) cantilevered restraint and significantly alter the dynamic response of the shell structure.To address this problem, constraint equations are used to properly connect adjacent shell- andsolid-element modeled structures. Basically, all such constraints express the deflection. (androtation for shell elements) of a node, R1, on one Structural component in terms of thedeflections/rotations of the corresponding point, P2, on the other connected component.Specifically, the element containing P2 is identified and the deformations at P2 determined byinterpolation between the element nodes. The following types of shell-solid element connectionsare used in the steam dryer model including the following:1. Connections of shell faces to Solid faces (Figure 10a). While only displacement degreesof freedom are explicitly constrained, this approach also implicitly constrains therotational degrees of freedom when multiple shell nodes on a sufficiently dense grid areconnected to the same solid face.2. Connections of shell edges to solids (e.g., connection of the bottom of closure plates withthe upper ring). Since solid elements do not have rotational degrees of freedom, thecoupling approach consisted of having the shell penetrate into the solid by one shellthickness and then constraining both the embedded shell element nodes (inside the solid)and the ones located on the surface of the solid structure (see Figure 10b). Numericaltests involving simple structures showed that this approach and penetration depthreproduce both the deflections and stresses of the same structure modeled using onlysolid elements or ANSYS' bonded contact technology. Continuity of rotations anddisplacements is achieved.The use of constraint conditions rather than the bonded contacts advocated by ANSYS forconnecting independently meshed structural components confers better accuracy and usefulnumerical advantages to the structural analysis of the steam dryer including better conditionedand smaller matrices. The smaller size results from the fact that equations and degrees offreedom are eliminated rather than augmented (in Lagrange multiplier-based methods) byadditional degrees of freedom. Also, the implementation of contact elements relies on the use ofvery high stiffness elements (in penalty function-based implementations) or results in indefinitematrices (Lagrange multiplier implementations) with poorer convergence behavior compared topositive definite matrices.The steam dryer rests on four support blocks which resist vertical and lateral displacement.The support blocks contact the seismic blocks welded to the USR so that 100% of the dryerweight is transmitted through the seismic blocks per the FDDR KG1-265. Because the contactregion between the blocks and steam dryer is small, the seismic blocks are considered free to27 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationrotate about the radial axis. Specifically nodal constraints (zero relative displacement) areimposed over the contact area between the seismic blocks and the support blocks. Two nodes oneach support block are fixed as indicated in Figure 11. One node is at the center of the supportblock surface facing the vessel and the other node is 0.5" offset inside the block towards thesteam dryer, half way to the nearest upper support ring node. This arrangement approximates thenonlinear contact condition where the ring can tip about the block.28 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information[1CEMasses areconnected to -top and bottomsupportsPoint massesGussets to liftingrods connectionsSSkirt to support"- rings connectionsI/L-SimplysupportedrestraintsA/IFigure 8. Point masses representing the vanes. The pink shading represents where constraintequations between nodes are applied (generally between solid and shell elements, point massesand nodes and , Inc. Proprietary InformationFigure 9b. Close up of mesh showing on-site modifications.31 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 9c. Close up of mesh showing drain pipes and hood supports.32 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 9d. Close up of mesh showing node-to-node connections between various plates.33 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 9e. Close up of mesh showing node-to-node connections between the skirt and drainchannels; hood supports and hoods; and other parts.34 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 9f. Close up view of tie bars.35 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationShell nodes DOF are related to solid element shape functionsSurface of solid elementFigure 10a. Face-to-face shell to solid connection.Surface of solid elementFigure 1 Ob. Shell edge-to-solid face connection.36 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 11. Boundary conditions. Inside node is half way between outer surface of support blockand upper support ring.37 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information3.10 Pressure LoadingThe harmonic loads are produced by the pressures acting on the exposed surfaces of thesteam dryer. At every frequency and for each MSL, the pressure distribution corresponding to aunit pressure at the MSL inlet is represented on a three-inch grid lattice grid (i.e., a mesh whoselines are aligned with the x-, y- and z-directions) that is superimposed over the steam dryersurface. This grid is compatible with the 'Table' format used by ANSYS to 'paint' generalpressure distributions upon structural surfaces. The pressures are obtained from the Helmholtzsolver routine in the acoustic analysis [9].In general, the lattice nodes do not lie on the surface, so that to obtain the pressuredifferences at the surface it is necessary to interpolate the pressure differences stored at thelattice nodes. This is done using simple linear interpolation between the 8 forming nodes of thelattice cell containing the surface point of interest. Inspection of the resulting pressures atselected nodes shows that these pressures vary in a well-behaved manner between the nodes withprescribed pressures. Graphical depictions of the resulting, pressures and comparisons betweenthe peak pressures in the original nodal histories and those in the final surface load distributionsproduced in ANSYS, all confirm that the load data are interpolated accurately and transferredcorrectly to ANSYS.The harmonic pressure loads are only applied to surfaces above the water level, as indicatedin Figure 12. In addition to the pressure load, the static loading induced by the weight of thesteam dryer is analyzed separately. The resulting static and harmonic stresses are linearlycombined to obtain total values which are then processed to calculate maximum and alternatingstress intensities for assessment in Section 5.(3)]] This is useful since revisions in the loadsmodel do not necessitate recalculation of the unit stresses.38 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNODESPRES-NORMz-.101592 .04099 36 468738-.030301 .397447 .540029Figure 12a. Real part of unit pressure loading MSL A (in psid) on the steam dryer at 50.1 Hz.No loading is applied to the submerged surface and lifting rods.39 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationANNODESPRE S-NORMx4 z.394932.295671494193Figure 12b. Real part of unit pressure loading MSL A (in psid) on the steam dryer at 200.45 Hz.No loading is applied to the submerged surface and lifting rods.40 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information4. Structural AnalysisThe solution is decomposed into static and harmonic parts, where the static solution producesthe stress field induced by the supported structure subjected to its own weight and the harmonicsolution accounts for the harmonic stress field due to the unit pressure of given frequency in oneof the main steam 'lines. All solutions are linearly combined, with amplitudes provided by signalmeasurements in each steam line, to obtain the final displacement and stress time histories. Thisdecomposition facilitates the prescription of the added mass model accounting for hydrodynamicinteraction and allows one to compare the stress contributions arising from static and harmonicloads separately. Proper evaluation of the maximum membrane and membrane+bending stressesrequires that the static loads due to weight be accounted for. Hence both static and harmonicanalyses are carried out.4.1 Static AnalysisThe results of the static analysis are shown in Figure 13. The locations with highest stressinclude the inner vane bank connection to inner base plate near support brackets with stressintensity 9,598 psi. There are four locations with artificial stress singularity, which are excludedfrom the analysis. The static stresses one node away are used at these locations as more realisticestimate of local stress. These locations are at the connections of the inner end plate to the innerbase plate at the ends of the cut-out, as shown in Figure 13c.4.2 Harmonic AnalysisThe harmonic pressure loads were applied to the structural model at all. surface nodesdescribed in Section 3210. Typical stress intensity distributions over the structure are shown inFigure 14. Stresses were calculated for each frequency, and results from static and harmoniccalculations were combined.To evaluate maximum stresses, the stress harmonics including the static component aretransformed into a time history using FFT, and the maximum and alternating stress intensities forthe response, evaluated. According to ASME B&PV Code,Section III, Subsection NG-3216.2the following procedure was established to calculate alternating stresses. For every node, thestress difference tensors, 6im = (n -0m, are considered for all possible pairs of the stresses anand am at different time levels, t, and tin. Note that all possible pairs require consideration* sincethere are no "obvious" extrema in the stress responses. However, in order to containcomputational cost, extensive screening of the pairs takes place (see Section 2.3) so that pairsknown to produce alternating stress intensities less than 250 psi are rejected. For each remainingstress difference tensor, the principal stresses Si, S2, S3 are computed and the maximum absolutevalue among principal stress differences, Sn =max{IS1 -s21,1s1-s31,1s2-s31}, obtained. Thealternating stress at the node is then one-half the maximum value of Snm taken over allcombinations (n,m), i.e., Salt= lmax { Snm }. This alternating stress is compared against allowablen,mvalues, depending on the node location with respect to welds.41 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNODAL SOLUTIONSTEP=1SUB =1TIME=1USUM (AVG)RSYS=ODMX =.068847SMN =.505E-03SMX =.068847.505E-03 .015 i067 .061254.008099 .05366 .068847Figure 13a. Overview of static calculations showing displacements (in inches). Maximumdisplacement (DMX) is 0.069". Note that displacements are amplified for visualization.42 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationAN1000 W 5000Figure 13b. Overview of static calculations showing stress intensities (in psi). Maximum stressintensity (SMX) is 9,598 psi. Note that displacements are amplified for visualization43 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information"-1--i>'/____7__ 'T_X.IIzFigure 13c. Stress singularities. Model is shown in wireframe mode for clarity.44 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNODAL SOLUTIONSTEP=1185SUB =1FREQ=50. 418REAL ONLYSINT (AVG)DMX =.195193SMN =.081579SMX =11642.081579 2587 ,1 103481294 ,9055 11642Figure 14a. Overview of harmonic calculations showing real part of stress intensities (in psi)along with displacements. Unit loading MSL A at 50.1 Hz (oriented to show high stress locationsat the hoods).45 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationMN..--- 644. 744 ... M- 4512 5801Figure 14b. Overview of harmonic calculations showing real part of stress intensities (in psi)along with displacements. Unit loading MSL A at 200.5 Hz.46 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information4.3 Post-ProcessingThe static and transient stresses computed at every node with ANSYS were exported intofiles for subsequent post-processing. These files were then read into separate customizedsoftware to compute the maximum and alternating stresses at every node. The maximum stresswas defined for each node as the largest stress intensity occurring during the time history.Alternating stresses were calculated according to the ASME standard described above. For shellelements the maximum stresses were calculated separately at the mid-plane, where onlymembrane stress is present, and at top/bottom of the shell, where bending stresses are alsopresent.For nodes that are shared between several structural components or lie on junctions, themaximum and alternating stress intensities are calculated as follows. First, the nodal stresstensor is computed separately for each individual component by averaging over all finiteelements meeting at the node and belonging to the same structural component. The timehistories of these stress tensors are then processed to deduce the maximum and alternating stressintensities for each structural component. Finally for nodes shared across multiple componentsthe highest of the component-wise maximum and alternating stresses is recorded as the "nodal"stress. This approach prevents averaging of stresses across components and thus yieldsconservative estimates for nodal stresses at the weld locations where several components arejoined together.The maximum stresses are compared against allowable values which depend upon the stresstype (membrane, membrane+bending, alternating -Pm, Pm+Pb, Salt) and location (at a weld oraway from welds). These allowables are specified in the following section. For solid elementsthe most conservative allowable for membrane stress, Pm, is used, although bending stresses arenearly always present also. The structure is then assessed in terms of stress ratios formed bydividing allowables by the computed stresses at every node. Stress ratios less than unity implythat the associated maximum and/or alternating stress intensities exceed the allowable levels.Post-processing tools calculate the stress ratios, identifying the nodes with low stress ratios andgenerating files formatted for input to the 3D graphics program, TecPlot, which provides moregeneral and sophisticated plotting options than currently available in ANSYS.4.4 Computation of Stress Ratios for Structural AssessmentThe ASME B&PV Code,Section III, subsection NG provides different allowable stresses fordifferent load combinations and plant conditions. The stress levels of interest in this analysis arefor the normal operating condition, which is the Level A service condition. The loadcombination for this condition is:Normal Operating Load Combination = Weight + Pressure + ThermalThe weight and fluctuating pressure contributions have been calculated in this analysis and areincluded in the stress results. The static pressure differences and thermal expansion stresses aresmall, since the entire steam dryer is suspended inside the reactor vessel and all surfaces areexposed to the same conditions. Seismic loads only occur in Level B and C cases, and are notconsidered in this analysis.47 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationAllowable Stress IntensitiesThe ASME B&PV Code,Section III, subsection NG shows the following (Table 6) for themaximum allowable stress intensity (Sm) and alternating stress intensity (Sa) for the Level Aservice condition. The allowable stress intensity values for type 304 stainless steel at operatingtemperature 550'F are taken from Table 1-1.2 and Fig. 1-9.2.2 of Appendix I of Section III, in theASME B&PV Code. The calculation for different stress categories is performed in accordancewith Fig. NG-3221-1 of Division I,Section III, subsection NG. The allowable value foralternating stress is taken from curve C of Fig. 1-9.2.2 in Appendix I in Section III of the ASMEB&PV Code.Table 6. Maximum Allowable Stress Intensity and Alternating Stress Intensity for all areasother than welds. The notation Pm represents membrane stress; Pb represents stressdue to bending; Q represents secondary stresses (from thermal effects and grossstructural discontinuities, for example); and F represents additional stress increments(due to local structural discontinuities, for example).Type Notation Service Limit Allowable Value (ksi)Maximum Stress Allowables:General Membrane Pm Sm 16.9Membrane + Bending Pm + Pb 1.5 Sm 25.35Primary + Secondary Pm + Pb + Q 3.0 Sm 50.7Alternating Stress Allowable:Peak = Primary + Secondary + F Salt Sa 13.6When evaluating welds, either the calculated or allowable stress was adjusted, to accountfor stress concentration factor and weld quality. Specifically:" For maximum allowable stress intensity, the allowable value is decreased by multiplyingits value in Table 6 by 0.55.* For alternating stress intensity, the calculated weld stress intensity is multiplied by a weldstress intensity (fatigue) factor of 1.8 for a fillet weld and 1.4 for a full penetration weld,before comparison to the Sa value given above.The weld factors of 0.55 and 1.4 (full penetration weld) or 1.8 (fillet weld) were selectedbased on the observable quality of the shop welds and liquid penetrant NDE testing of all welds(excluding tack and intermittent welds, which were subject to 5X visual inspection) duringfabrication. These factors are consistent with fatigue strength reduction factors recommended bythe Welding Research Council, [25], and stress concentration factors at welds, provided in [26]and [27]. In addition, critical welds are subject to periodical visual inspections in accordancewith the requirements of GE SIL 644 SIL and BWR VIP-139 [28]. Therefore, for weld stressintensities, the allowable values are shown in Table 7. These factors (0.55 and 1.4 or 1.8) alsoconservatively presume that the structure is joined using fillet welds unless specified otherwise.Since fillet welds correspond to larger stress concentration factors than other types. of welds, thisassumption is a conservative one.48 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 7. Weld Stress Intensities.Type Notation Service Limit Allowable Value (ksi)Maximum Stress Allowables:General Membrane Pm 0.55 Sm 9.30Membrane + Bending Pm + Pb 0.825 Sm 13.94Primary + Secondary Pm + Pb + Q 1.65 Sm 27.89Alternating Stress Allowables:Peak = Primary + Secondary + F Salt Sa 13.6Comparison of Calculated and Allowable Stress IntensitiesThe classification of stresses into general membrane or membrane + bending types was madeaccording to the exact location, where the stress intensity was calculated; namely, generalmembrane, Pm, for middle surface of shell element, and membrane + bending, Pm + Pb, forother locations. For solid elements the most conservative, general membrane, Pm, allowable isused.The structural assessment is carried out by computing stress ratios between the computedmaximum and alternating stress intensities, and the allowable levels. Locations where any of thestresses exceed allowable levels will have stress ratios less than unity. Since computation ofstress ratios and related quantities within ANSYS is time-consuming and awkward, a separateFORTRAN code was developed to compute the necessary maximum and alternating stressintensities, Pm, Pm+Pb, and Salt, and then compare it to allowables. Specifically, the followingquantities were computed at every node:1. The maximum membrane stress intensity, Pm (evaluated at the mid-thickness location forshells),2. The maximum membrane+bending stress intensity, Pm+Pb, (taken as the largest of themaximum stress intensity values at the bottom, top, and mid thickness locations, forshells),3. The alternating stress, Salt, (the maximum value over the three thickness locations istaken).4. The stress ratio due to a maximum stress intensity assuming the node lies at a non-weldlocation (note that this is the minimum ratio obtained considering both membrane stressesand membrane+bending stresses):SR-P(nw) = min{ Sm/Pm, 1.5

• Sm/(Pm+Pb) }.5. The alternating stress ratio assuming the node lies at a non-weld location,SR-a(nw) = Sa / (1.1

• Salt),6. The same as 4, but assuming the node lies on a weld,SR-P(w)=SR-P(nw)

• 0.557. The same as 5, but assuming the node lies on a weld,SR-a(w)=SR-a(nw) / fsw.49 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNote that in steps 4 and 6, the minimum of the stress ratios based on Pm and Pm+Pb, is taken.The allowables listed in Table 7, Sm=16,900 psi and Sa=13,600 psi. The factors, 0.55 and fsw,are the weld factors discussed above with fsw=1.8 being appropriate for a fillet weld and fsw=1.4for a full penetration weld. The factor of 1.1 accounts for the differences in Young's moduli forthe steel used in the steam dryer and the values assumed in alternating stress allowable.According to NG-3222.4 in subsection NG of Section III of the ASME Code [3], the effect ofelastic modulus upon alternating stresses is taken into account by multiplying alternating stressSalt at all locations by the ratio, E/Emodel= 1., where:E = 28.3 106 psi, as shown on Fig. 1-9.2.2. ASME BP&V CodeEmodel = 25.55 106 psi (Table 2)The appropriate maximum and alternating stress ratios, SR-P and SR-a, are thus determined anda final listing of nodes having the smallest stress ratios is generated. The nodes with stress ratioslower than 4 are plotted in TecPlot (a 3D graphics plotting program widely used in engineeringcommunities [29]). These nodes are tabulated and depicted in the following Results Section.4.5 (3)11(3)50 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information1[(3)]]51 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5. Modifications Implemented to Meet EPU Stress MarginsThe dryer analyzed in Section 5 [10] identified several locations with alternating stress ratiosbelow the EPU target of 2.0 when subjected to the ACM Rev. 4.1 acoustic loads. To achieve thedesired EPU stress margins several modification were proposed and analyzed in Section 6 of thesame report. These evaluations were carried out using (3). Thepresent section provides definitive specifications of the required modifications that wereimplemented in the NMP2 dryer for EPU operation. The collection of modifications organizedinto the following distinct groups:Group 1: The lifting rod bracket/side plate welds. The upper and middle bracketsalready have weld reinforcement, but this does not reduce stresses sufficientlyunder the new loads.Group 2: The middle hood reinforcement strip incurs a high stress due to vibration ofthe outboard section of the middle hood.Group 3: The inner hood/hood support welds that experience high stresses due to theinner hood vibrations.Group 4: The remaining points which are readily modified to achieve SR-a>2.0 at EPU.Group 5: Closure plate welds which are addressed by adding reinforcement strips tothese plates.Below, these groups are discussed in further detail. In this discussion the "pre-modified" state ofsteam dryer is taken to be its configuration before the Group 1-5 modifications wereimplemented (i.e., the NMP2 configuration prior to the Spring 2012 outage).5.1 Lifting Rod Support Brackets (Group 1)Without any modification other than an increase in the existing weld size from 1/4" to 1/22"which, (3)it was determined on the basis of CLTP loads that the limiting alternating stress locations wouldoccur on the lifting rod support brackets. (see Figure 15) with an alternating stress ratio below2.76 at CLTP, which, using a velocity square-based scaling would indicate an alternating stressratio below 2.0 at EPU. The stresses were highly localized (only one node on each such bracketis affected) which is indicative of development of stress singularities at this re-entrant corner. Itwas further established that with the weld reinforcement, the lower-most brackets had sufficientstress margin and only the middle and upper brackets did not meet the target stress ratios. Forthese brackets further weld reinforcement appeared unlikely by itself to achieve the necessarystress reductions. Instead a more substantial structural reinforcement was developed.The localized nature of the stress concentration called for a corresponding localizedreinforcement. Several such concepts were proposed in [10]. There it was shown that increasingthe local thickness -specifically that of all elements with at least one node on the verticalplate/brace weld line -from 0.375" to 0.75" satisfactorily reduced the stress and did not52 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationsignificantly impact the modal properties or stresses elsewhere on the steam dryer. Of thevarious concepts considered, Concept 2 was recommended as it provided substantial stressreduction while requiring less severing, grinding and re-welding than some of the other concepts.This configuration shown in Figure 16 consists of a 2" radius, 0.375" thick circular disk weldedto the vertical plate and a small reinforcement plate, shaped to match the re-entrant comercontour as shown, is welded onto the support bracket to increase the effective thickness andthereby reduce the membrane stress. By examining the maximum stress in the unit solutionstresses over the 128-145 Hz frequency range (which brackets the dominant frequencies for thislocation in the global solution) it was shown that this reinforcement reduces the maximum stressby a factor of 0.18 (Table 11 of [10]).The design finalized here builds upon the semi-circular disc concept 2 but is modified toeliminate any cutting of existing welds. It consists of a 2.5" wide by 3" high 3/8" thickrectangular plate with a 1.5" long and 1" wide slot cut out as indicated in Figure 17. Thedimensions are selected so that the plate can slide over the existing 0.25" brace attachment weld(WI). Note that the total width of the existing 0.25" double sided fillet weld is 2x0.25" (twofillets) plus 0.375" (brace plate thickness) or 0.875". The larger 1" slot accommodates possibleirregularities in the actual weld. The length of the slot is sized so that the plate can slide up tothe existing weld (again accounting for possible irregularities in the wrap around portion of theexisting weld) and leave sufficient room for a 0.375 fillet weld (W2) around its perimeter. Theplate and slot has 1/4" rounded fillets. The installation process begins by sliding this plate overthe brace and attaching it to the vertical plate by a 3/8" fillet weld as indicated in Figure 17.Next a 1/2" weld (W4) is created as shown in Figure 18 to attach the 3/8" brace reinforcementplates. These welds are continued to the right along the entire length of the vertical plate/bracejoint wrapping around the end. This allows continued used of the SRF=0.64 for this reinforcedweld line. The attachment is completed by adding a 1/4" weld W5 to attach the bracereinforcement plates to the brace. A top view of the brace reinforcement plate is shown in Figure19. The plate is 5" long by 1.25" wide and trimmed at a 47.5 deg. angle as indicated so that theedge is parallel to the existing weld jpining the two plates comprising the lifting rod brace.This reinforcement is used for the middle and top lifting rod braces. For the lowest bracesadequate stress margin is achieved by increasing the existing weld size to V2, allowingapplication of (3) to this weld as shown in [30].Prior to final design and installation it was required that available photographs of the as-builtlifting rod brace installations be reviewed to ensure that there is adequate clearance relative toexisting welds and to ensure proper fitting of the new components. For example, reference to thephotograph in Figure 20 suggests that proper fitting of the vertical plate will entail milling out astep on the face adjacent to the vertical plate to accommodate the closure plate and its attachmentweld.53 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information1.2075"6"ElrIFigure 15. Basic geometry of lifting rod brace. The lifting rod slides through the circular holeand the brace is attached to the vane bank vertical plate.Figure 16. Reinforcement concept 2: Partial reinforcement -semi-circular plate one side plate(red) and reinforcement of re-entrant comer on support bracket (blue)54 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information0.40.50210-1,. 3/8- Plate2.5' (W) x 3" (H)rBraceW1W2Vertical PlateBrace* zW2'7*VerticalReinforcementPlateFigure 17. Schematic of reinforcement. WI is the existing 0.25" weld; W2 is the new 0.375"weld for attaching the vertical reinforcement plate.55 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationW4W4S>0W4 BraceReinforcementPlatesFigure 18. Additional welds. The 0.5" fillet weld, W4, attaches the 3/8" brace reinforcementplates to the vertical reinforcement plate. The weld continues on over the existing braceattachment weld. W5 attaches the brace reinforcement plates to the existing brace.56 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationI/I1Figure 19. Depiction of brace reinforcement plate.57 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 20. As built lifting rod brace.58 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5.2 Middle Hood/Reinforcement Strip (Group 2)Application of the Rev. 4.1 CLTP acoustic loads to the pre-modified steam dryer induced astrong response on the section of the middle hood lying between the closure plate and the verticalreinforcement strip (see Figure 21), and produced stresses along this strip that exceeded targetlevels. This strip was originally added to address indications on the outboard section of themiddle hood. The high stresses occur on the 1/8" middle hood rather than within the muchthicker strip (additional 3/8") and are dominated by a 109.0 Hz signal which, at the +10% shift,excites a structural response at 119.9 Hz.In Section 6 of [10] it was reasoned that a local modification was unlikely to rectify the highstress, but merely shift its location slightly. Therefore, to reduce the stress it was proposed tosuppress the active oscillation by covering this section of the middle hood with a 3/8" curvedplate welded about. its perimeter to the hood and closure plate. Manufacture of the plate isstraightforward and creating the attachment weld does not pose accessibility challenges.However, since each such plate would weigh approximately 90 lbs and stress evaluations showedthat all previously limiting locations on the hood acquired very high alternating stress ratios(SR-a>20) after the modification it was surmised that adequate stress reduction could easily beachieved using thinner reinforcement plates.Therefore the steam dryer stress evaluation was repeated by replacing the previous 3/8"curved reinforcement plate by one that is 1/8" thick thus increasing the effective thickness of thehood section to 1/4". Unit solution stresses of the complete steam dryer with this modified middlehood section (and also the other planned reinforcements -reinforced closure plate and addedmasses on the inner and middle hoods as discussed below) were developed in the 30-250 Hzfrequency range. This range: (i) encompasses the frequency where stresses are highest and (ii)ensures that any higher order modes occurring at higher frequencies are fully accounted for.Recalculation of the stresses at the Group 2 locations results in CLTP stresses that are below1300 psi which maintains ample margin for EPU operation.It was recommended that the panels be trimmed to size such that the plate edges reach towithin 1/8" of the existing welds on the closure plate and the reinforcement strip. A 3/16" inchfillet weld is then applied around the perimeter of the reinforcement plate.59 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 8. Group 2 CLTP stresses after adding 1/8th reinforcement plate over the middle hoodsection lying between the existing reinforcement strip and closure plate.Location node Pm Pm+Pb Sa SR-P SR-a % Freq. Dom.Shift Freq. [Hz]2. Hood Reinforcement/Middle Hood 98275 200 497 362 28.07 18.96 0 135.48. Hood Reinforcement/Middle Hood 90126 981 1462 381 9.47 18.05 5 51.29. Hood Reinforcement/Middle Hood 98268 352 597 377 23.34 18.24 2.5 135.410. Hood Reinforcement/Middle Hood 90949 993 1112 321 9.36 21.36 -5 140.9i Middle hood sectionoutboard of closure plate-thickness increased by1/8".Figure 21. Middle hood section subject to modification and existing reinforcement strip.60 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5.3 Inner Hoods/Hood Support (Group 3)In the pre-modified steam dryer configuration the inner hoods and to a lesser extent also themiddle hoods, showed a strong stress response on the hood/hood support welds in the 45-60 Hzrange. The stresses resulted from strong vibrations of the central sections of the inner andmiddle hoods and did not meet the required margin for EPU operation. Since the acoustic loadson these hoods are relatively low, these vibrations are caused by transmission of loads from othersteam dryer components such as the directly forced outer hoods. Since the welds, particularly athigher elevations, are difficult to access and reinforce it was necessary to pursue alternatemodifications. One option was to stiffen the hood panels and suppress vibrations by addingreinforcement strips at the modal displacement response peaks. This would generally result insimilar response modes occurring at upward-shifted natural frequencies. However, examinationof the MSL signals indicates that these signals increase with frequency so that an upward shift inthe hood frequencies would place these frequencies into a range with stronger MSL signals.Therefore the option pursued was to add small 15 lb masses on the inner hoods. Specificallyone such mass was added to each of four central inner hood sections as indicated in Figure 22.Each mass is located 18" below the top of the vane bank surface since this is approximately thereach length of a submerged diver welding the masses to the inner hoods. The addition of themasses lowers the natural response frequencies and reduces the modal amplitudes (since thegeneralized masses of the participating modes are reduced). These masses were added into theglobal model and unit solutions regenerated over the 30-250 Hz frequency range (in conjunctionwith the other modifications to the dryer including the thickened closure plates, middle hoodmasses and middle hood reinforcement described for Group 2). As shown in Section 6.2, withthese masses in place all locations meet the required margins.Using a density of 0.284 lb/in3 for stainless steel it follows that the volume of the 15 lb massis 52.8 in3.It was originally proposed to employ a rounded 8"x8" 1" thick rectangular mass withtwo interior slits -a lower 6" slit and an upper 3" slit -added for additional weld support (seeError! Reference source not found.). The mass would be attached with a 1/4/4" weld around thetop and side edges (the bottom edge is considered inaccessible to diver reach) and the same sizedweld around the interior perimeters of the two slits. The bottom face of the mass would belocated at 18" below the top of the vane bank. Theupper and lower slots were added to allow foradditional attachment welds. Due to additional manufacturing requirements and installationconstraints these masses were modified while maintaining the total mass and CG locationconstant.. Stress evaluations of the redesigned masses and their attachment welds confirmed thatadequate stress margin was maintained.61 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 22. The inner hood sections (blue) whose response contributes to the high stresses on thecentral hood support/inner hood weld. Middle and outer hoods excluded from view to exposeinner hood surfaces. Proposed masses are added 18" below the top of the vane bank.62 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationI[(3)]]63 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5.4 Group 4 LocationsUnder a previous load definition three families of locations were identified as havingalternating stress ratios between 2.65 and 2.76 before modifications [10]. Because theselocations were close to, but did not meet the target margin it was natural to collect these locationsinto a single fourth group. To meet EPU margin, modifications were developed for the group 4members and assessed on the basis of the older loads. The modifications identified for theselocations are described below. Assessment of the modifications for the hood/hood support/baseplate junction and of the bottom of the drain channel/skirt weld is (3).The following locations were addressed under group 4.(a) Outer hood/hood support/cover plate junctions. These points lie on the commonintersection between the hood, hood support and base plate. To alleviate the stress a stress reliefcut-out hole in the hood support was incorporated. A detailed evaluation of this modificationwas developed in Section 3.4 and Appendix A. 11 of [7] showing that the stress reduction factorachieved with (3). The semi-circular stress relief cut-out hole canbe generated using electrical discharge machining (EDM) that can be implemented remotely thusreducing diver dose to at most the period required to attach the device to the hood support.(b) Bottoms of the drain channel/skirt welds. These locations are easily accessible and Can bereinforced by adding a wrap-around reinforcement weld to alleviate the stress. Specifically, itwas proposed to increase the existing bottom 4" of weld to a thickness of 0.25" and wrap theweld around the bottom of the drain channel and 1" up on the interior side of the junction. InSection 3.1 of [7] a stress reduction factor of (3). Without application of the SRF, the limiting alternatingstress ratio at CLTP was shown to be SR-a=3.06. Therefore, using the up-to-date CLTP loaddefinition this location met the required stress margin without any modification needed. Whenthe stress reduction factor is invoked the limiting stress ratio at CLTP for this weld increased toSR-az=4.84 and occurredon a point that is 1" above the bottom of the drain channel/skirt junctionwhere the SRF is in fact not applied.(c) Middle hood/hood support welds; High stresses occur on the middle hood/hood supportwelds due to vibrations of the middle hoods. The stresses at these locations have been addressedby adding a total of four 10 lb masses on the central sections of the middle hoods. Thesefunction in a manner similar to the masses employed for the inner hoods. However, because alesser reduction is needed the masses are smaller than those installed on the inner hoods. Otherthan a reduction in the lower ledge height to achieve the required mass, all other details of themass design are identical to that attached to the inner hood. The middle hood masses are placedat the same 18" depth measured from the top of the vane bank as the inner hood masses. Theimpact on stress of adding these masses in and also the other reinforcements including thereinforced closure plates, inner hood masses and reinforced middle hood section outboard of theclosure plate was quantified by generating unit solutions with all modifications implementedover the 30-250 Hz frequency range and applying the ACM Rev. 4.1 loads. With thesemodifications the limiting alternating stress ratio at this location SR-a=3.71 at CLTP.64 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationThe resulting changes in the stress ratios for the Group 4 locations when implementing allsteam dryer modifications are summarized in Table 9.Table 9. Alternating stress ratios for group 4 locations before and after modifications.Location Modification SR-a (at CLTP)Pre- Post-Modification Modification(a) Hood Support/Outer Base Cut-out in hood support (SRF=0.80, Section 3.4 2.29 2.83Plate/Middle and Appendix A.11 in [7])Backing Bar(b) Submerged Drain Wrap around weld (SRF=0.56, Section 3.1 in 3.06 4.84Channel/Submerged Skirt [7]))(c) Hood Support/Middle Hood Added 10 lb mass 2.94 (1) 3.71Note: (1). Pre-modification value is estimated as follows. In [2] it was shown that the limitingalternating stress ratios on the middle hood/hood support weld were 2.68 before modification(Table 6 in [2]) and 3.38 after modification (Entry 16 in Table 10 of [2]). This implies a stressincrease of 26% when removing the middle hood masses. The pre-modification value is thusestimated as SR-a=3.71/1.26.5.5 Group 5 Locations -Modification of Closure PlatesThe pre-modification closure plates are 1/8 in thick and contained a structural mode near128 Hz. This mode is a second order mode in the vertical direction and first order in thehorizontal direction. In preliminary analyses of the dryer these plates were found to respondstrongly to a 135.7 Hz component in the acoustic signal which when shifted by -10% duringfrequency shifting, couples closely to the closure plate frequency. The response mode inducedhigh stresses along the lateral welds connecting the closure plate to the vane bank (a straightvertical weld) and to the adjacent hood (a mostly vertical weld, but curved to accommodate thehood geometry). The highest stresses generally occurred at the top of this weld. However,significant stresses also developed on these weld lines between 10-20 inches below the top of theweld. This corresponds to the weld locations nearest the maximum displacement of this mode.In preliminary stress assessments made for the dryer where noise was filtered from the signal onthe basis of low power measurements, several locations on the closure plate welds emerged ashaving stress ratios that do not meet target levels at EPU. These locations were addressed byperforming a (3). In some cases, addition of an interior weld or thickening of the existing weld (seeSection 2.2) was required to achieve acceptable stress ratios.With updated acoustic loads processed with the ACM Rev. 4.1 (and where low powersubtraction is not performed) the closure plate weld reinforcements were found insufficient toachieve the target EPU stress margin. Rather than pursue further weld reinforcement, which islimited in regard to both access (finite arm reach limits the length of weld that can be producedon the interior side of the closure plate) and prospect for improvement (making weld legssignificantly larger than the plate thickness does not necessarily improve the stresses), it was65 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationdecided to reinforce the closure plate itself to simultaneously reduce stresses and separatestructural mode and peak acoustic frequencies.(3)]]With the closure plate reinforcement and other steam dryer modifications it is determinedthat the previous closure plate attachment weld reinforcements are no longer needed and theexisting welds are sufficient to meet the EPU stress margins. (3)66 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationW 510OFigure 23: Second mode shape (f=-128.45 Hz) of unmodified closure plates67 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationI'NCI)AL SCLUTICNSTEP=1SUB =1FREQ=259.55USUMRSYS=oEMX =17.218SF.a-P27.778SMX =17.21803.8267.65211.47815.3051.913 5.739 9.565 13.391 17.218Figure 24: Fundamental mode shape (f=259.6 Hz) of modified closure plate.68 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information............................................................ .............I..P3°............ ........... .......................................................4.. F-7.000.ft11,000O-.5OO0.500.... .....,....0 0 ......--- -0.500S................................... ..........................................44. .............................I..--I I- 0.5000.5000,500Figure 25. Closure Plate Modification -Geometry (0.5"w x 0.75"h Beam (from [31])69 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5.6 Summary of ModificationsThe dryer modifications are summarized in Table 10. To implement the modifications 1, 4, 5 and 8 unit solutions wereregenerated over the 30-250 Hz frequency range with these modifications in place. Below 30 Hz the unit solutions for the originalunmodified dryer were used. Since the original dryer had no significant stress response below 30 Hz, the splitting of the unit solutionsin this manner is acceptable. For the remaining locations (3).iThe, unit solutions arecombined with the MSL signals in the manner described in Section 2 to obtain the results in Section 6.Table 10. Summary of modifications made to the NMP2 steam dryer.Reinforcement / Modification Details FEA Implementation1. Add reinforcement ribs to all (8) closure plates. Section 5.5 Closure plates are thickened to obtain dynamicallyequivalent structure a described in Section 3.52. Increase weld of the lowest lifting rod-brace/vertical Section 5.4;plate welds to 0.5" Section 3.5in (3)]][713. Reinforce middle and upper lifting rod braces to Section 5.1 Reduce stresses by 0.18 at this location based on FEAeliminate stress concentration on weld to vertical plate. reductions shown for Concept 2 in Table 11 of [10])4. Add 1/8" thick plate over the middle hood section Section 5.2 Thicken the existing plate by 1/8".lying between the closure plate and existing reinforcementstrip.5. Add total of four 15 lb masses to the central sections of Section 5.3 Place 15 lb point masses on the inner hoods at thethe inner hoods. mass centers.6. Add stress relief cut-out at the bottom edge of the outer Section 5.4;hood supports. Section 3.4 in[7] (3)]]7. Reinforce the bottom of the drain channel/skirt weld Section 5.4;with thickened wrap-around weld. Section 3.1 in (3)]]P7]8. Add total of four 10 lb masses to the central sections of Section 5.4 Place 10 lb point masses on the middle hoods at thethe middle hoods. mass centers.70 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information5.7 Final (As-Built) Modifications and InstallationIn order to facilitate installation and access during underwater welding operations themodification designs described above were refined and analyzed in more detail prior toinstallation. The adjustments made were negligible with regard to the global analysis since: (i)integral properties such as added mass and overall stiffness of the structure were unchanged sothat deviations in mode shapes and natural frequencies from those analyzed in the full steamdryer model would be negligible; and (ii) the modifications generally occurred on a level ofdetail that was finer than considered in the global model. An example of the latter involves aweld used to attach a 15 lb mass to the inner hood. This weld was extended by 1" relative to thedesign and the extension analyzed in detail to show it reduced the maximum weld stress by a1.5%. Such details are not resolved on the global model with a 2.5 in mesh spacing but areinstead conservatively compensated for by imposing an overall bias (9.53%) on the stresspredictions to account for finite mesh size. In addition to these adjustments, additionalinformation, such as tolerances for the outer hood support cut-outs and closure platereinforcement rib installations, was developed to provide appropriate manufacturing andinstallation constraints.The refinements to the modification groups are summarized below:Group 1: The lifting rod bracket/side plate welds are essentially unchanged from thedesigned configurations.Group 2: The original design of the reinforcement plate attached to the middle hoodlocated outboard of the closure plate did not include an adequate standoffbetween the perimeter of the reinforcement plate and adjacent structuralelements thus posing welding difficulties. Consequently a 2.25 in standoffand beveling of the reinforcement plate perimeter were incorporated. Thisconfiguration was reanalyzed to ensure that stresses remain acceptable anddetermined that at CLTP the limiting conservative alternating stress ratio onthe plate reduced from SR-a=3.47 to 3.02 which remains well above margin.Group 3: The 15 lb masses attached to the inner hoods were modified to facilitatewelding and installation without altering the mass and center of gravity. Asshown in Figure 26 the added mass structure has evolved into a thinner platewith an upper rounded edge and the mass concentrated on the lower part. Therounded upper edge allows for a longer weld length while concentrating themass towards the bottom shortens the required reach of the welder to theattachment welds. Dynamic stress analyses of the masses added to the globalsteam dryer model (see Figure 27) confirmed that stresses near and on theattachment welds remain acceptable [6] for more detail).Group 4: The 10 lb masses added to the central panels of the middle hoods weremodified to match the final 15 lb inner hood mass designs except for thethickness and height of the lower ledge where the mass is concentrated -thisledge is modified so that the correct mass and center of gravity location aremaintained.. The 10 lb mass geometry is shown in Figure 28. Other thanproviding tolerances for the outer hood support cutouts near the outerhood/cover plate junction, there were no other adjustments to the Group 4designs.71 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationGroup 5: Tolerances on the vertical positioning of the reinforcement ribs weredeveloped. The rib cross-section was modified by incorporating a chamfer toimprove weld access, ensure good weld quality and minimize heat transfer tothe closure plate. The resulting cross-section was analyzed to ensure adequatebending stiffness and fundamental frequency (i.e., >250 Hz) of the closureplate are maintained. Finally, due to clearance requirements it was necessaryto reposition the lower-most rib by 2.5" relative to the original design. Thisconfiguration was evaluated and determined to acceptable.Complete details of the design adjustments and associated stress evaluations are provided in [6].72 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information21-b we Aft-M& "Ovomo Afin-dnMuMMMA MA I I II ihIMMOMU~a ft2LUZIK JAAMTUA MULOA3I191C FrXM13 MIIAHIA MMNMM ASW*R PC00 SVR314M0DA ~sWM05 MriX3nu1XM# I~.iW M* inIM04OVIMMAwinT0XMWM D09CInuPMWAPInwUBEAP F segu54W436M&00" T AIOE1 $"I-W.JL ME.ITIMI UUIBYWO POO FIhtmMr-.12211OETALAISOMETFUC VIEWMmSCCIOE6L Bs1o" 3A X"4 /F6-BIASC.E 2 WML MOM DR19OM to WH- DOMG0 PMenENIMM MIE1 FOR tEE= HM~KMMM I -f NIE MLE POIT_______ MJQKEAR8STATION 2~119M.U -C10082C95 2A4321Figure 26. Drawing of 15 lb added mass from Appendix E in [32].73 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 27. 15 lb masses embedded into the global model. Top -overview; bottom -close up ofmesh near added masses.74 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information21mw~,w.mdm.* *~a~IIb~~..F~U.U~Z (1~ 4. dghrt.ein~ SIII W miWAPMTHAN II -ef MJ)D,v17u I 1 NOECO MW LB WASS 1P1.I.U1. MA TB FM C 1 W M SHO Tn CI BEDGES, 4 4O~~T~lCLI T4 A TOSDA FANOC BnM IN) .S FITMUM SY W I~~emRUFM 3NONNGh& BX P UAWU M L CHE M WSFFCSFE ISM0OSESEKt' S4li43Q=USm1ASTU AM T SON. (IN & ISD-.13Ul~CCDIEALR~ASCAL2,AB/BBWALE 55015~S~i inw~A~ baGCEMM IN PAITIESES (ýA IAFM RBR ONL.YAAN we NO MLEPOIN* wstu~Tu mau8N MJ(EMR STATENi 2~ -,etnininIW ~STEAM DRYER MOE HOOD7W .-fdlý V -ulO MA SSA; c 7 1008C96 27 -3-3 -1- sa- ASm=. OWA4321Figure 28. Drawing of 10 lb added mass from Appendix E in [32].75 This Document Does Not. Contain Continuum Dynamics, Inc. Proprietary Information6. ResultsThe stress intensities and associated stress ratios resulting from the Rev. 4.1acoustic/hydrodynamic loads [4, 5] with associated biases and uncertainties factored in, arepresented below. The bias due to finite frequency discretization and uncertainty associated withthe finite element model itself, are also factored in. In the following sections the highestmaximum and alternating stress intensities are presented to indicate which points on the dryerexperience significant stress concentration and/or modal response (Section 6.1). The loweststress ratios obtained by comparing the stresses against allowable values, accounting for stresstype (maximum and alternating) and location (on or away from a weld), are also reported(Section 6.2). Finally the frequency dependence of the stresses at nodes experiencing the loweststress ratios is depicted in the form of accumulative PSDs (Section 6.3).In each section results are presented both at nominal conditions (no frequency shift) and withfrequency shift included. Unless specified otherwise, frequency shifts are generally performed at2.5% increments. The tabulated stresses and stress ratios are obtained using a 'blanking'procedure that is designed to prevent reporting a large number of high stress nodes fromessentially the same location on the structure. In the case of stress intensities this procedure is asfollows. The relevant stress intensities are first computed at every node and then nodes sortedaccording to stress level. The highest stress node is noted and all neighboring nodes within 10inches of the highest stress node and its symmetric images (i.e., reflections across the x=0 andy=0 planes) are "blanked" (i.e., excluded from the search for subsequent high stress locations).Of the remaining nodes, the next highest stress node is identified and its neighbors (closer than10 inches) blanked. The third highest stress node is similarly located and the search continued inthis fashion until all nodes are either blanked or have stresses less than half the highest value onthe structure. .For stress ratios, an analogous blanking procedure is applied. Thus the loweststress ratio of a particular type in a 10" neighborhood and its symmetric images is identified andall other nodes in these regions excluded from listing in the table. Of the remaining nodes, theone with the lowest stress ratio is reported and its neighboring points similarly excluded, and soon until all nodes are either blanked or have a stress ratio higher than 5.The acoustic loads applied to the steam dryer are obtained using the most recent andcomplete strain gage signals [5] and processed using the-ACM Rev. 4.1 analysis with associatedbiases and uncertainties updated to reflect the new revision as described in [4]. For the FEMstructural model there are three main contributors to the bias and uncertainty. The first is anuncertainty (21.5%) that accounts for modeling idealizations (e.g., vane bank mass model),geometrical approximations and other discrepancies between the modeled and actual dryer suchas neglecting of weld mass and stiffness in the FEA. The second contributor is a bias of 9.53%accounting for discretization errors associated with using a finite size mesh, upon computedstresses. The third contributor is also a bias and compensates for the use of a finite discretizationschedule in the construction of the unit solutions. The frequencies are spaced such that at 1%damping the maximum (worst case) error in a resonance peak is 5%. The average error for thisfrequency schedule is 1.72%.76 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information6.1 General Stress Distribution and High Stress LocationsThe maximum stress intensities obtained by post-processing the ANSYS stress histories forEPU at nominal frequency and with frequency shift operating conditions are listed in Table 11.Contour plots of the maximum stress intensities with all frequency shifts included are shown inFigure 29. The figures are oriented to emphasize the high stress regions. Note that these stressintensities do not account for weld factors but do include end-to-end bias and uncertainty.Further, it should be noted that since the allowable stresses vary with location, stress intensitiesdo not necessarily correspond to regions of primary structural concern. Instead, structuralevaluation is more accurately made in terms of the stress ratios which compare the Computedstresses to allowable levels with due account made for stress type and weld. Comparisons on thebasis of stress ratios are made in Section 6.2.The maximum stress intensities in most areas are low (less than 1000 psi). For themembrane stresses (Pm) the high stress regions tend to occur at: (i) the bottom of the centralvertical side plate that joins the innermost vane banks (stress concentrations occur where thisplate is welded to the inner base plates resting on the upper support ring); (ii) the welds joiningthe tie bars to the top cover plates on the vane banks; (iii) the seismic blocks that rest on thesteam dryer supports; (iv) the bottoms of the inner vane bank side plates where they connect tothe USR; and (v) the closure plate welds. For these locations the stresses are dominated by thestatic contribution as can be inferred from the small alternating stress intensities (Salt) tabulatedin Table 11 for the high Pm locations. From Figure 29a higher Pm regions are seen to be in thevicinity of the supports where all of the dryer deadweight is transmitted, the closure platesconnecting the inner hoods to the middle vane banks, and various localized concentrations suchthose along the bottom of the outer hood.The membrane +/- bending stress (Pm+Pb) distributions evidence a more pronounced modalresponse especially on the inner and middle hood structures. High stress concentrations arerecorded on the bottom edge of the central vertical plate where it joins to the USR (immediatelyaboVe the support blocks) and the inner vane bank. Other areas with high Pm+Pb stressconcentrations include: (i) the tops of the closure plates where they are welded to a hood or vanebank end plates; (ii) the skirt/drain channel welds; (iii) the outer cover plates connecting to theupper support ring and bottom of the outer hoods; (iv) the common junction between each hood,its hood support (or stiffener), and (v) the central panels of the inner and (to a lesser extent)middle hoods (see Figure 29b-c).The alternating stress, Salt, distributions are most pronounced on the inner and middle hoods.The highest stress intensity at any frequency shift at a non-weld location occurs on the innerhood. Though not exposed directly to the MSL acoustic sources, these hoods are thinner than theouter ones and their response is driven mainly by structural coupling rather than direct forcing.Significant response is also observed on the outer hoods nearest the MSL inlet acoustics.Numerous weld locations also show significant stress including the bottoms of drain channelsand the junctions between the hoods, hood supports and base plates. These locations arecharacterized by localized stress concentrations as indicated in Figure 29e and have emerged ashigh stress locations in other steam-dryers also. Other locations with high alternating stressintensities include the tie bar/top cover plate weld, the weld joining the lifting rod braces to thevertical vane bank end plate and welds involving the closure plate.77 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationComparing the nominal results (Table 11 a) and results with frequency shifting (Table 1 lb) itcan be seen that maximum stress intensities, Pm and Pm+Pb, do not differ significantly. Thehighest alternating stress is approximately 25.0% higher when frequency shifts are considered.78 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 1 a. Locations with highest predicted stress intensities for EPU conditions with no frequency shift.Stress Location Weld SRF(a) Location (in) node Stress Intensities (psi) Dom.Category x y z Pm Pm+Pb Salt Freq. (Hz)Pm Inner Side Plate No 3.1 119 0.5 37229 7545 8933 570 73.9Upper Support Ring (USR)/Support/Seismic Yes -6.9 -122.3 -9.5 113554 7271 7271 945 15.5BlockSide Plate, Ext/Inner Base Plate Yes 16.3 119 0 94143 6985 9878 544 44.9Tie Bar Yes 49.3 108.1 88 141275 6228 6228 1182 97.4Side Plate/Closure Plate/Top Plate Yes -47.1 -108.6 88 91558 5674 6267 1009 199.0Pm+Pb Side Plate Ext/Inner Base. Plate Yes 16.3 119 0 94143 6985 9878 544 44.9Inner Side Plate No 3.1 119 0.5 -37229 7545 8933 570 73.9Side Plate/Top Plate Yes 49.6 108.6 88 93256 2584 8882 1637 97.4Side Plate/Top Plate Yes 17.6 119 88 91215 964 7654 1732 69.4Middle Base Plate/Inner Hood/Backing Bar Yes -39.9 -108.6 0 84197 532 7381 1451 71.3Salt Inner Hood. No -32.4 27 72.4 81316 1350 4052 3799 44.9Brace .No 79.6 85.5 75.8 37811 3580 3617 3529 136.7" Middle Hood No 63.6 -30 73.3 34.302 1267 3483 3324 61.2" Inner Hood No 31.4 -36.1 77.1 70582 1053 3027 2848 44.5" Middle Hood No 63.2 -18.3 [ 75.4 34769 816. 2883 2755 61.2Notes: (a) [[(b) Full penetration weld so that weld factor, WF=1.4(1-5) 'Number referring to the (3) Entry is empty if no SRF is applied.(3)]]79 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 1 lb. Locations with highest predicted stress intensities taken over all frequency shifts at EPU conditions.Stress Location Weld SRF(a) Location (in) node Stress Intensities (psi) % Freq. Dom.Category x y z Pm Pm+Pb Salt Shift Freq. (Hz)Pm Inner Side Plate No 3.1 119 0.5 37229 7600 9091 737 -10 70.8" USR/Support/Seismic Block Yes -6.9 -122.3 -9.5 113554 7460 7460 1118 -10 14.2Side Plate Ext/Inner Base Plate Yes 16.3 119 0 94143 7092 10071 712 7.5 101.0" Tie Bar Yes 49.3 108.1 88 141275 6391 6391 1273 10 91.1Top Plate/Side Plate/Closure Plate Yes -47.1 -108.6 88 91558 5940 6670 1290 7.5 195.5Pm+Pb Side Plate Ext/Inner Base Plate Yes 16.3 119 0 94143 7092 10071 712 7.5 101.0Side Plate/Top Plate Yes 49.6 108.6 88 93256 2610 9167 1790 10 91.1" Inner Side Plate No 3.1 119 0.5 37229 7600 9091 737 5 70.8" Side Plate/Top Plate Yes 17.6 119 88 91215 994 7829 1986 5 69.8Middle Base Plate/Inner Backing Yes -39.9 -108.6 0 84197 586 7729 1854 7.5 52.1Bar/Inner HoodSalt Inner Hood No -32.4 27 72.4 81316 1632 5221 4778 -7.5 60.8__" Brace No 79.6 85.5 75.8 37811 3624 3854 3722 -2.5 134.3" Inner Hood No 31.4 -36.1 77.1 70582 1165 3773 3660 -7.5 60.6" Middle Hood No -64.8 24.8 67.6 30488 923 3488 3361 5 59.5" Inner Hood No 31.8 -16.2 75.4 70627 907 3202 3162 -7.5 60.6Notes: (a) [[(b) Full penetration weld so that weld factor, WF=1.4(1-5) Number referring to the (3) Entry is empty if no SRF is applied.(3)]]80 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationzPm [psi]7500675060005250450037503000225015007500Figure 29a. Contour plot of maximum membrane stress intensity, Pm, for EPU operation withfrequency shifts. The recorded stress at a node is the maximum value taken over allfrequency shifts. The maximum stress intensity is 7600 psi.81 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationzX YPm+Pb [psi]100009000800070006000500040003000200010000Figure 29b. Contour plot of maximum membrane+bending stress intensity, Pm+Pb, for EPUoperation with frequency shifts. The recorded stress at a node is the maximumvalue taken over all frequency shifts. The maximum stress intensity is 10071 psi.First view.82 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 29c. Contour plot of maximum membrane+bending stress intensity, Pm+Pb, for EPUoperation with frequency shifts. Second view from beneath.83 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationzSalt [psi]460040003500300025002000150010005000Figure 29d. Contour plot of alternating stress intensity, Salt, for EPU operation with frequencyshifts. The recorded stress at a node is the maximum value taken over all frequencyshifts. The maximum alternating stress intensity is 4778 psi. First view.84 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationSalt [psi]450040003500300025002000150010005000Figure 29e. Contour plot of alternating stress intensity, Salt, for EPU operation with frequencyshifts. The recorded stress at a node is the maximum value taken over all frequencyshifts. Second view from below.85 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information6.2 Load Combinations and Allowable Stress IntensitiesThe stress ratios computed for EPU at nominal frequency and with frequency shifting arelisted in Table 12 (without frequency shifting) and Table 13 (with frequency shifting). The stressratios are grouped according to type (SR-P for maximum membrane and membrane+bendingstress, SR-a for alternating stress) and location (away from welds or on a weld). The tabulatednodes with frequency shifting in Table 13 are also depicted in Figure 30. The plotscorresponding to maximum stress intensities depict all nodes with stress ratios SR-P_<5 orSR-P_<4 as indicated, and the plots of alternating stress ratios display all nodes with SR-a<5.For EPU operation at nominal frequency (no frequency shift) the minimum stress ratio isidentified as a maximum stress, SR-P=1.28, and is recorded on upper support ring where it restson the support block. This stress at this location is dominated by the static stress due todeadweight and is only weakly responsive to acoustic loads as can be seen from the highalternating stress ratio at this location (SR-a>6.15 at all frequency shifts). This is true for all fournodes having the lowest values of SR-P, all having SR-a>5.32 at all frequency shifts. Theminimum alternating stress ratio at zero frequency shift, SR-a=3.09, occurs on the weldconnecting the middle hood, hood support and outer base plate.The effects of frequency shifts are conservatively accounted for by identifying the minimumstress ratio at every node, where the minimum is taken over all the frequency shifts considered(including the nominal or 0% shift case). The resulting stress ratios are then processed as beforeto identify the smallest stress ratios anywhere on the structure, categorized by stress type(maximum or alternating) and location (on or away from a weld). The results are summarized inTable 13 and show that the lowest stress ratio, SR-P=1.25, occurs at the same location as in thenominal case and is only slightly lower. Moreover, the limiting value closely matches thatpredicted in [1] at CLTP. Again this is due to the dominance of static contributions andcomparatively weak dependence on acoustic loads. The next three lowest SR-P locations inTable 13b are the same as in Table 12b. With frequency shifting the lowest alternating stressratio occurs at a different location, the side plate/end plate weld of the inner vane bank (seelocation 1 in Figure 30h) and assumes a value of SR-a=2.49. Based on the largest Fouriercoefficient, the dominant frequency contributing to this stress is 142 Hz. In addition to this weldthe first several limiting nodes involve the bottom of a hood/hood support weld (locations 2, 9and 10, with dominant frequencies 51-52 Hz and 66 Hz), the end of a tie bar (locations 4, 5, 7, 8and 13, with dominant frequencies 69 Hz and 61 Hz), or a closure plate (location 6,. dominantfrequency 70 Hz). More details of the stress response spectra are provided in the followingsection. In the CLTP-based stress evaluation [1] the limiting node location was node 95267.This is a mirror node of 99337 (the sign of y is reversed) which is the second entry in Table 13c.It is noted that in Table 13c the application of an SRF is only required for entry 12 (node87633) which corresponds to the both lifting rod brace. The other locations achieve analternating stress ratio, SR-a>2 even when the SRF is set to unity.In the most recent previous stress evaluation [1] using loads obtained at CLTP the limitingalternating stress ratio was SR-a=2.83 which, using a velocity squared scaling corresponds to analternating stress ratio of SR-a=2.83/1.382=2.05 at EPU. This prediction is conservative relativeto the value of SR-a=2.49 obtained using actual EPU loads which can be attributed to the86 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationconfluence of one or more of the following explanations. First, the measured steam flow at EPUwas 115.5% [5] rather than the analysis assumption of 117.56%. This reduces the velocitysquared scaling factor from 1.38 to 1.33 so that the alternating stress ratio at EPU obtained byscaling the CLTP value would be SR-a=2.83/1.33=2.13. Furthermore, NMP2 has indicated thepotential that an additional 1% to 1.5% measurement + bias exists reducing the actual flow to114.5%. The velocity square scaling factor in that case would be 1.31 and the correspondingalternating stress ration inferred using this factor would be SR-a=2.16.Second, it is known that the-measured signals are contaminated with noise associated withstructural vibrations, sensor noise (contributing to a noise floor) and other possible non-acousticsources such as MSL turbulence. Except for coherence filtering, no attempt to remove this noiseis made so that for the purposes of stress evaluation it is effectively treated as acoustic. A poweris increased the noise contributions generally remain approximately constant or scale at a ratethat is slower than the velocity-square scaling associated with acoustic sources. Thus whenpower is increased one expects that a signal combining an acoustic contribution (which scaleswith velocity squared) and a non-acoustic part (which grows more slowly or remains constant)will scale at a rate somewhat less than velocity squared. Thus one expects that the alternatingstress ratios obtained from actual plant measurements at EPU will be larger (stresses will belower) than those obtained by scaling the values measured at CLTP.Another contributing explanation is that the [[(3)Finally, when the CLTP data used to calculate the stresses in [1] was collected, a strain gagechannel was dropped on both the upper and lower MSL D measurement locations. This meansthat there was a higher degree of contamination by structural vibration resulting in higherestimates of acoustic loads. Note that since structural vibrations are coherent the coherence filterwould not be effective in removing these non-acoustic signals. In the data collected at 115%CLTP and used to prepare the results in Table 12 and Table 13 all data channels were operativeat the upper station in MSL D. At the lower MSL D station one channel was again absent, butsince the structural contributions to the signals at the upper and lower MSL D locations are lesslikely to be coherent (because they are essentially absent at the upper location) the coherencefilter removes them from the final signal. Removal of these non-acoustic structural contributionsto the signals results in lower and more accurate stress estimates.87 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 12a. Limiting non-weld locations with at EPU conditions with no frequency shift. Stress ratios are grouped according to stresstype (maximum -SR-P; or alternating -SR-a).Stress Location Location (in.) node Stress Intensity (psi) Stress Ratio Dom.Ratio x y z Pm Pm+Pb Salt SR-P SR-a Freq. (Hz)SR-P 1. Inner Side Plate 3.1 119 0.5 37229 7545 8933 570 2.24 21.71 73.92. Thin Vane Bank Plate -15.6 -118.4 0.6 2558 4841 5253 281 3.49 > 40 44.93. Support/Seismic Block 10.2 123.8 -9.5 113286 4566 4566 1485 3.70 8.33 15.5SR-a 1; Inner Hood -32.4 27 72.4 81316 1350 4052 3799 6.26 3.25 44.9" 2. Brace 79.6 85.5 75.8 37811 3580 3617 3529 4.72 3.50 136.7" 3. Middle Hood 63.6 -30 73.3 34302 1267 3483 3324 7.28 3.72 61.288 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 12b. Limiting peak stress ratios, SR-P, on Welds at EPU conditions with no frequency shift. Bold text indicates minimum stressratio on the structure.Location SRF(a) Location (in.) node Stress Intensity (psi) Stress Ratio Dom.x y z Pm Pm+Pb Salt SR-P SR-a Freq. (Hz)1. USR/Support/Seismic Block -6.9 -122.3 .-9.5 113554 7271 7271 945 1.28 7.27 15.52. Side Plate Ext/Inner Base Plate 16.3 119 0 94143 6985 9878 544 1.33 12.62 44.93. Tie Bar 49.3 108.1 88 141275 6228 6228 1182 1.49 5.81 97.44. Side Plate/Closure Plate/Top Plate -47.1 -108.6 88 91558 5674 6267 1009 1.64 6.80 199.0S. Inner Side Plate/Inner BasePlate 2.3 119 0 98446 4653 7968 681 1.75 10.08 73.96. Side Plate/Top Plate 17.6 119 88 91215 964 7654 1732 1.82 3.97 69.47. Hood Support/Outer Base Plate/Middle Backing Bar -71.3 0 0 95428 5079 5388 2178 1.83 3.15 53.68. Closure Plate/Backing Bar/Inner Hood 39.9 108.6 0.5 93062 5060 5121 801 1.84 8.58 70.89. Hood Support/Middle Base Plate/Backing Bar/Inner 39.9 0 0 88639 4884 5031 1976 1.90 3.48 70.8Hood(b)10. Vane Bank Plate/Hood Support/Inner Base Plate 24.1 -59.5 0 85191 4859 4940 1237 1.91 5.55 54.411. Hood Support/Outer Cover Plate/Outer Hood(4) 0.8 -102.8 28.4 0. 95267 4800 4915 2192 1.94 *3.13 54.412. Outer Cover Plate/Outer Hood 102.8 -58.1 0 94498 1039 7166 901 1.95 7.63 11.513. Hood Support/Middle Base Plate/Backing Bar/Inner 39.9 -59.5 0 101435 4442 4738 1562 2.09 4.40 44.1Hood(b)Notes: (a) [[(b) Full penetration weld so that weld factor, WF=1.4.(1-5) Number referring to the (3) Entry is empty if no SRF is applied.(3)]]89 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 12c. Limiting alternating stress ratios, SR-a, on welds at EPU conditions with no frequency shift.Location SRF(a) Location (in.) node Stress Intensity (psi) Stress Ratio Dom.x y z Pm Pm+Pb Salt SR-P SR-a Freq. (Hz)1. Hood Support/Outer Base Plate/Backing Bar 71.3 0 0 98067 4669 5074 2219 1.99 3.09 44.12. Side Plate/Top Plate -80.2 -85.2 88 93031 522 2779 2217 5.02 3.10 71.33. Closure Plate/Middle Hood 60.2 -85.2 87 89317 1216 5186 2203 2.69 3.12 71.04. Hood Support/Inner Hood(b) -36.8 0 46.9 95644 836 2384 2198 5.85 3.12 44.4.5. Hood Support/Inner Hood(b) 32.4 0 72.5 99540 577 2472 2194 5.64 3.13 55.46. Hood Support/Outer Cover Plate/Outer 0.80 -102.8 28.4, 0 95267 4800 4915 2192 1.94 3.13 54.4Hood(4)7. Top Plate/Middle Hood/Top Plate 55.6 -28.4 88 90955 899 2600 2093 5.36 3.28 61.28. DoubleSide Plate/Top Plate 49.3 0 88 93197 1200 2884 2091 4.83 3.29 70.89. Hood Support/Middle Hood(b) 63.8 0 72.5 98462 500 2281 2062 6.11 3.33 61.210. Hood Support/Inner Hood(b) -38.2 0 34.9 95638 801 2033 2028 6.86 3.39 44.111. Tie Bar/Top Plate(2) 0.77 -81.1 85.2 88 99456 914 4324 2026 3.22 3.39 71.312. Inner Hood/Top Plate 24.1 -30.6 88 85512 773 2228 1991 6.26 3.45 55.413. Hood Support/Middle Base Plate/Backing 39.9 0 0 88639 4884 5031 1976 1.90 3.48 70.8Bar/Inner Hood.b)14. Side Plate/Top Plate 17.6 0 88 95617 1144 2709 1962 5.15 3.50 71.3Notes: (a) [[(b) Full penetration weld so that weld factor, WF=I.4.(1-5) Number referring to the (3) Entry is empty if no SRF is applied.(3)]]90 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 13a. Limiting non-weld locations with at EPU conditions with frequency shifts. Stress ratios are grouped according to stresstype (maximum -SR-P; or alternating -SR-a). Locations are depicted in Figure 30.Stress Location Location (in.L node Stress Intensity (psi) Stress Ratio % Freq. Dom.Ratio x y z Pm Pm+Pb Salt SR-P SR-a Shift Freq. (Hz)SR-P 1. Inner Side Plate 3.1 119 0.5 37229 7600 9091 737 2.22 16.78 -10 70.82. Thin Vane Bank Plate -15.6 -118.4 0.6 2558 4898 5321 318 3.45 38.92 5 14.43. Support/Seismic Block 10.2 123.8 -9.5 113286 4618 4618 1574 3.66 7.86 10 13.9SR-a 1. Inner Hood -32.4 27 72.4 81316 1632 5221 4778 4.86 2.59 -7.5 60.82. Brace 79.6 *85.5 75.8 37811 3624 3854 3722 4.66 3.32 -2.5 134.33. Inner Hood 31.4 -36.1 77.1 70582 1165 3773 3660 6.72 3.38 -7.5 60.64. Middle Hood -64.8 24.8 67.6 30488 923 3488 3361 7.27 3.68 5 59.591 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 13b. Limiting peak stress ratios, SR-P, on welds at EPU conditions with frequency shifts. Bold text indicates minimum stressratio on the structure. Locations are depicted in Figure 30.Location SRF(a) Location (in.) node Stress Intensity (psi) Stress Ratio % Freq. Dom.x y z Pm Pm+Pb Salt SR-P SR-a Shift Freq. (Hz)1. USR/Support/Seismic Block -6.9 -122.3 -9.5 113554 7460 .7460 1118 1.25 6.15 -10 14.22. Side Plate Ext/Inner Base Plate 16.3 119 0 94143 7092 10071 712 1.31 9.65 7.5 101.03. Tie Bar 49.3 108.1 88 141275 6391 6391 1273 1.45 5.40 10 91.14. Side Plate/Closure Plate/Top Plate -47.1 -108.6 88 91558 5940 6670 1290 1.56 5.32 7.5 195.55. Inner Side Plate/Inner Base Plate -2.3 -119 0 99200 4533 8367 896 1.67 7.67 7.5 69.86. Hood Support/Outer Base Plate/Middle -71.3 0 0 95428 5297 5388 2454 1.75 2.80 5 51.2Backing Bar7. Side Plate/Top Plate 17.6 119 88 91215 994 7829 1986 1.78 3.46 5 69.88. Hood Support/ Cover 0.8 -102.8 28.4 0 95267 5181 5343 2695 1.79 2.55 5 52.1Plate/Outer Hood(4)9. Hood Support/Middle Base 39.9 0 0 88639 5181 5193 2010 1.79 3.42 10 40.5Plate/Inner Backing Bar/Inner Hood(b)10. Middle Base Plate/Backing Bar/Inner Hood -39.9 -108.6 0 84197 586 7729 1854 1.80 3.71 7.5 52.111. VaneBank Plate/Hood Support/Base Plate -24.1 59.5 0 99487 5126 5232 1569 1.81 4.38 7.5 44.912. Outer Cover Plate/Outer Hood 102.8 -58.1 0 94498 1078 7303 1072 1.91 6.41 10 10.513. Hood Support/Middle Base -39.9 59.5 0 90468 4569 4674 1822 2.03 3.77 -5 69.8Plate/Backing Bar/Inner Hood(b)Notes: (a)(b)Full penetration weld so that weld factor, WF=I.4.(3)]] Entry is empty if no SRF is applied.(1-5) Number referring to the (3)92 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 13c. Limiting alternating stress ratios, SR-a, on welds at EPU conditions with frequency shifts. Locations are depicted inFigure 30.Location SRF(a) Location (in.) node Stress Intensity (psi) Stress Ratio % Freq. Dom.x y z Pm Pm+Pb Salt SR-P SR-a Shift Freq. (Hz)1. Vane Bank Plate/Side Plate/End Plate -24.1 119 11.6 90170 842 3084 2757 4.52 2.49 7.5 142.02. Hood Support/Outer Cover Plate/Outer Hood (4) 0.8. -102.8 -28.4 0 99337 3681 4009 2704 2.53 2.54 5 52.13. Side Plate/End Plate -24.1 119 21.9 90232 912 2905 2687 4.80 2.56 5 146.14. Side Plate/Top Plate 17.6 0 88 95617 1381 3359 2644 4.15 2.60 5 69.45. Side Plate/Top Plate -49.3 0 88 97693 1220 3420 2641 4.08 2.60 2.5 69.86. Closure Plate/Middle Hood 60.2 -85.2 87 89317 1341 5726 2638 2.43 2.60 2.5 70.17. Side Plate/Top Plate -80.2 -85.2 88 93031 556 3048 2617 4.57 2.62 5 69.48. Top Plate/Inner Hood 24.1 -30.6 88 85512 785 2698 2575 5.17 2.67 -7.5 60.69. Hood Support/Outer Base Plate/Backing Bar -71.3 0 0 95428 5297 5388 2454 1.75 2.8 5 51.210. Hood Support/Middle Base Plate/Backing -39.9 0 '0 85723 5130 5381 2418 1.81 2.84 7.5 66.4Bar/Inner Hood(b)11. Side Plate/Top Plate -54 -54.3 88 85117 607 2641 2410 5.28 2.85 5 69.412. Side Plate/Brace(5) 0.64 79.7 -85.2 31.2 87633 2735 2901 2404 3.40 2.86 7.5 123.513. Top Plate/Side plate/Inner Hood (3) 0.83 24.1 -27.8 88 90897 889 2702 2367 5.16 2.90 -7.5 60.614. Outer Cover Plate/Outer Hood -102.8 -1 0 95236 1302 2741 2359 5.09 2.91 -10 60.615. Hood Support/Inner Hood(b) 32.4 0 72.5 99540 631 2627 2347 5.31 2.93 -10 61.316. End Plate/inner Hood -39.3 115.1 20.5 95777 1941 2787 2306 4.79 2.98 5 146.117. Tie Bar 17.6 59.8 88 137575 3258 3258 2301 2.85 2.98 10 65.518. Outer End Plate/Outer Hood -97.9 -69.4 58.4 99213 856 2427 2273 5.74 3.02 2.5 69.8Notes: (a) [[(b) Full penetration weld so that weld factor, WF=1.4.(1-5) Number referring to the (3) Entry is empty if no SRF is applied.(3)]]93 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationzTSR-P4.8d4.6;4.4.....4.2g4a...3.8 .... 0 03.6NI d3.4O'~O.OFiur 3a Lcaiosofmiimmstes rtos S-P5associtdwt maxmu "stsesanon-wlds fr EP opertionwith requncy sifts The ecored stess atioi h iiuvalue~~~~~~~~~~*Qa taeovralfrqecuhfs Tenmesrfrs oteeueae oainfrS-valus a no-weds n Tble1 3. Tis iewshos'lctin..ad394 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information4.404.2 '443.841 t.W4.6 WM3.4 ýN.Figure~~~~~~~~~~~~~~~~~~~. U.4Lctosofmnmmsrs rtoS- sscae ihmxiu tessano-ed4o.2 prto it rqec hfs h eode tesrtoi h iiuvau 4ae vr lrqec shits.Thumbr reer toteeuertdlctinfrS-value at on-wlds n Tale 13a his iew shw locaton.295 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationSR-a4.84.64.44.243.83.63.43.232.82.6Figure 30c. Locations of minimum alternating stress ratios, SR-a_<5, at non-welds for EPUoperation with frequency shifts. The recorded stress ratio at a node is the minimum value takenover all frequency shifts. Numbers refer to the enumerated locations for SR-a values at non-welds in Table 13a. View showing locations 1 and 4.96 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Informationzx4.84.64.44.243.83.63.43.232.82.6Figure 30d. Locations of minimum alternating stress ratios, SR-a<5, at non-welds for EPUoperation with frequency shifts. The recorded stress ratio at a node is the minimum value takenover all frequency shifts. Numbers refer to the enumerated locations for SR-a values at non-welds in Table 13a. View showing locations 2 and 3.97 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationSR-P3.83.63.43.232.82.62.42.221.81.61.41.2Figure 30e. Locations of minimum stress ratios, SR-P<4, associated with maximum stresses atwelds for EPU operation with frequency shifts. The recorded stress ratio at a node is theminimum value taken over all frequency shifts. Numbers refer to the enumerated locations forSR-P values at welds in Table 13b. This view shows locations 1, 4, 5, 8 and 10.98 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationIzSR-P3.83.63.43.232.82.62.42.221.81.61.41.2Figure 30f. Locations of minimum stress ratios, SR-P<4, associated with maximum stresses atwelds for EPU operation with frequency shifts. The recorded stress ratio at a node is theminimum value taken over all frequency shifts. Numbers refer to the enumerated locations forSR-P values at welds in Table 13b. This view shows locations 2, 3, 7 and 12.99 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationxSR-P3.83.63.43.232.82.62.42.221.81.61.41.2Figure 30g. Locations of minimum stress ratios, SR-P<4, at welds for EPU operation withfrequency shifts. The recorded stress ratio at a node is the minimum value taken over allfrequency shifts. Numbers refer to the enumerated locations for SR-P values at welds in Table13b. This view from below shows locations 6, 8-11 and 13.100 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 30h. Locations of minimum alternating stress ratios, SR-a_<5, at welds for EPU operationwith frequency shifts. The recorded stress ratio at a node is the minimum value taken over allfrequency shifts. Numbers refer to the enumerated locations for SR-a values at welds in Table13c. This view shows locations 1, 3-8, 11, 13 and 15-17.101 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 30i. Locations of minimum alternating stress ratios, SR-a<<5, at welds for EPU operationwith frequency shifts. The recorded stress ratio at a node is the minimum value taken over allfrequency shifts. Numbers refer to the enumerated locations for SR-a values at welds in Table13c. View showing locations 2, 9, 10 and 14.102 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 30j. Locations of minimum alternating stress ratios, SR-a_<5, at welds for EPU operationwith frequency shifts. The recorded stress ratio at a node is the minimum value taken over allfrequency shifts. Numbers refer to the enumerated locations for SR-a values at welds in Table13c. View around locations 6 and 12.103 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationFigure 30k. Locations of minimum alternating stress ratios, SR-a<5, at welds for EPU operationwith frequency shifts. The recorded stress ratio at a node is the minimum value taken over allfrequency shifts. Numbers refer to the enumerated locations for SR-a values at welds in Table13c. View around locations 2, 4, 5, 7, 8, 11, 13, 14 and 18.104 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information6.3 Frequency Content and Filtering of the Stress SignalsThe frequency contribution to the stresses can be investigated by examining the powerspectral density (PSD) curves and accumulative PSDs for selected nodes having low alternatingstress ratios. The accumulative PSDs are computed directly from the Fourier coefficients aswhere &(cOk) is the complex stress harmonic at frequency, (Ok. Accumulative PSD plots areuseful for determining the frequency components and frequency ranges that make the largestcontributions to the fluctuating stress. Unlike PSD plots, no "binning" or smoothing offrequency components is needed to obtain smooth curves. Steep step-like rises in X(w) indicatethe presence of a strong component at a discrete frequency whereas gradual increases in thecurve imply significant content over a broader frequency range. From Parsival's theorem,equality between 4(0N) (where N is the total number of frequency components) and the RMS ofthe stress signal in the time domain is established.The selected nodes are the ones having the lowest alternating stress ratios (at a weld) in Table13c. These are:Node 90170 -located on the inner vane band side plate/end plate weld. This is the limitingalternating stress location. The associated PSDs are shown in Figure 31 a.Node 99337- located on the welded common junction between the outer hood, hood supportand outer cover plate. This node is a mirror image of the limiting alternating stresslocation (node 95267) at CLTP. The associated PSDs are shown in Figure 3 lb.Node 95617 -located on the weld joining the tie bar and inner vane bank top plate. Theassociated PSDs are shown in Figure 31 c.Node 89317 -located on the weld joining the closure plate and middle hood. The associatedPSDs are shown in Figure 3 1d.Node 87633 -located on the lifting rod brace/vane bank end plate connection. Theassociated PSDs are shown in Figure 31 e.These are the nodes labeled 1, 2, 4, 6 and 12 in Table 13c for alternating stresses on a weld andaccompanying Figure 30h-k.In each case; since there are six stress components and up to three different section locationsfor shells (the top, mid and bottom surfaces), there is a total of 18 stress histories per component.Moreover, at junctions there are at least two components that meet at the junction. The particularstress component that is plotted is chosen as follows. First, the component and section location(top/mid/bottom) is taken as the one that has the highest- alternating stress. This narrows theselection to six components. Of these, the component having the highest Root Mean Square(RMS) is selected. For comparison the PSDs and cumulative PSDs are also shown for the CLTPload examined in [1] at the shifts producing the highest stress intensity at that load.105 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationThe first node (90170) is dominated by a peak centered at near 152 Hz for the +7.5% shiftedcase (this corresponds to a 142 Hz peak shifted upward by the frequency shift). From theaccumulative PSD it is evident that frequency shifting increases this peak, but does not shift itsfrequency. This is indicative of a peak in the signal moving closer to a structural resonance. Avery similar behavior is observed for node 99337 which has a dominant frequency about 52.1 Hz(this was a significant frequency for the CLTP loads also). At the limiting +5% frequency shiftthis peak grows with frequency shift. The third node (95617) follows a similar behavior (Peakfrequency about 69 Hz) whereas the fourth node (89317) exhibits two distinct peaks. Finally fornode 87633, several peaks are present. In all cases the CLTP curves are qualitatively verysimilar to the EPU results after the expected adjustment for gross amplitude is made. Thisindicates that, as anticipated, neither the acoustic loads nor resulting stress response havedeveloped any significant new peaks.Another way to characterize the dominant frequencies is to plot the dominant frequency overthe dryer surface. For each finite element node the frequency associated. with the largest stressharmonic (at any frequency shift) is recorded. A contour map of this dominant frequency isshown in Figure 32. This map is useful in a qualitative sense for identifying what dryercomponents appear most responsive to particular frequencies. For most of the dryer, includingthe central section of the outer hoods, the inner hoods and most of the skirt the dominantfrequencies are in the 50-60 Hz range as indicated in Figure 32b. From Figure 32b the outersections of the outer hoods show peak frequencies near 65-75 Hz. The middle hoods respond inthe ranges 58-62 Hz whereas the inner hoods respond in the range 45-60 Hz.106 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNode 90170, aCl)a-E400350300250200150100500105104050 100 150 200Frequency [ Hz ]250Node 90170, a-1000i.10000U)"' 100101050 100 150 200250Frequency [ Hz ]Figure 3 Ia. Accumulative PSD and PSD curves of the axx stress response at node 90170.107 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNode 99337, a.5000.0-U)a-0f)E400300200I--IEPU +5% shifttCLTT -1%sshif.. ...... ....-.. .......... .........1000050100150200250Frequency [ Hz]Node 99337, or10610I)a-Clo" 100010010050 100 150 200 250Frequency [ Hz ]Figure 3lb. Accumulative PSD and PSD of the axx stress response at node 99337.108 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNode 95617, aYYa.75E400350300250200150100500050 100 150 200Frequency [ Hz ]250Node 95617, aYY10 5104T1000z0-10010050 100 150 200250Frequency [ Hz ]Figure 3 lc. Accumulative PSD and PSD of the cyy stress response at node 95617.109 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNode 89317, aYYC,)0-E350300250200150100500050 100 150 200Frequency [ Hz ]250Node 89317, aYY10 51041000a-10100101050 100 150 200250Frequency [ Hz ]Figure 31d. Accumulative PSD and PSD of the Oyy stress response at node 89317.110 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationNode 87633, ciyyC,)a..75E6005004003002001000i"-EPU -no shift--0-- EPU +7.5% shift _".. --X-- CLP+ 10%/, shift-------...................050 100150200250Frequency [ Hz]Node 87633, cy10510 4I1000100101..EPU -no shift-@- EPU +7.5% shiftCUP + 10% shift050100150200250Frequency [ Hz ]Figure 31 e. Accumulative PSD and PSD of the ayy stress response at node 87633.III This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationDom. Freq. [Hz]50454035302520151050xFigure 32a. Contour map showing the dominant frequencies (i.e., the frequency with the largeststress harmonic). This shows locations with dominant frequencies in the range 0-50 Hz.112 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationDoa. Freq. [Hz]7874706662585450zxFigure 32b. Contour map showing the dominant frequencies (i.e., the frequency with the largeststress harmonic). This shows locations with dominant frequencies in the range 50-80 Hz.113 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationDom. Freq. [Hz]2502402302202102001901801701601501401301201101009080zx4YFigure 32c. Contour map showing the dominant frequencies (i.e., the frequency with the largeststress harmonic). This shows locations with dominant frequencies in the range 80-250 Hz.114 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information6.4 Real Time Analysis With (i) 92.5 Hz signal Included and (ii) RCIC Line ClosedAs discussed in [5] it was established that during power ascension the MSL B loads wereaffected by the reactor core isolation cooling (RCIC) steam line configuration. As a result,additional tests and data collections were conducted to define the loads with the RCIC lineisolated as described in Appendix C of [5]. In this section the stresses resulting from twoadditional loads corresponding to different RCIC line configurations are calculated andcompared against the baseline EPU loads used in the full steam dryer stress analysis.The first load adds a 92.5 Hz peak to the baseline 115% CLTP load. This peak was observedin the MSL B data initially collected at 110% CLTP, but was not reproducible in the post-scramrecovery. To gage the impact of such a signal at 115% CLTP the peak was scaled and combinedwith the baseline 115% loads as described in [33]. The second load definition was collected at115% CLTP with the inboard RCIC valve temporarily closed. This resulted in a narrow peak onMSL B at 89.3 Hz. Both RCIC conditions are considered off-normal conditions correspondingto a short-duration technical specification limiting condition or to a transient loading associatedwith an unusual steam line drain configuration.In order to analyze these loads a subset of nodes with smallest stress ratios is selected andstresses re-evaluated at those locations only. The particular set of nodes is selected in a manner-similar to that used for real time stress evaluation during power ascension [34]. Specifically thelist is comprised of the following nodes:* All nodes with an EPU alternating stress ratio, SR-a<3.0. There are 41 such nodes on aweld and 7 more located away from a weld.* The RPS sub-set of nodes with 3.5<SR-a<4 at EPU. There are 36 such nodes on a weldand another 4 away from a weld.* The RPS set of nodes with SR-P<3 at EPU (skipping those already included in thepreceding set). There 18 such nodes on a weld and another node off the weld.All 107 nodes are processed with three different loads: the baseline EPU loads used in theremainder of this report, the loads with the 92.5 Hz signal artificially added and loads at EPUwith the RCIC line closed. The stress intensities are calculated in the same manner as whenanalyzing- the entire dryer and the limiting stresses With frequency shifting included are reported.The resulting stress-ratios are summarized in Table 14 together with the dominant frequency.For most nodes, addition of the 92.5 Hz signal has negligible effect upon the stress intensity.The exceptions occur for those components and limiting locations where the 92.5 Hz signal is thedominant component. The limiting alternating stress- ratio is SR-a=2.39.Closing the RCIC line has a more extended effect where all nodes experience a somewhatdifferent stress.with stress changing even when the dominant frequency remains unchanged. Thelimiting alternating stress ratio is SR-a=2.05.115 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTable 14. Stresses obtained at 107 locations using: (i) baseline EPU loads; (ii) the same EPU loads with a 92.5 Hz signal added asdescribed in [5, 33] and (iii) at EPU operation with the RCIC line closed.All non-weld nodes with SR-a<3Inner Hood 81316 -32.4 27.0 72.4 4.86 2.59 60.8 4.85 2.58 60.8 4.42 2.31 52.2Inner Hood 70703 32.9 -27.2 .69.8 5.27 2.66

• 60.6 5.27 2.66 60.6 4.52 2.25 60.5Inner Hood 70645 31.7 -31.1 75.6 5.49 2.73 60.6 5.49 2.73 60.6 4.58 2.27 60.5Inner Hood 70672 32.3 -28.2 73.0 5.26 2.73 60.6 5.25 2.73 60.6 4.51 2.27 60.5Inner Hood, 70588 31.6 -29.0 76.0 5.34 2.75 60.6 5.34 2.75 60.6 4.49 2.30. 60.5Inner Hood 70653 31.8 -33.4 75.1 5.55 2.85 60.6 5.55 2.85 60.6 4.63 2.38 60.5Inner Hood 70266 31.1 -33.7 78.1 5.83 2.94 60.6 5.82 2.94 60.6 4.88 2.43 60.5All nodes on weld with SR-a<3Vane Bank Plate/Side Plate/End Plate 90170 -24.1 119.0 11.6 4.52 2.49 142.0 4.53 2.49 142.0 3.92 2.16 147.4Hood Support/Outer Cover Plate/Outer Hood 99337 -102.8 -28.4 0.0 2.53 2.54 52.1 2.52. 2.53 52.1. 2.42 2.51 60.5Entry Bottom Perf/Side Plate/End Plate 90233 -24.1 119.0 20.0 4.81 2.55 146.1 4.81 2.55 146.1 4.26 2.20 147.4Hood Support/Outer Cover Plate/Outer Hood 95267 -102.8 28.4 0.0 1.79 2.55 52.1 1.79 2.58 52.1 1.63 2.27 60.5Entry Bottom Perf/Side Plate/End Plate 90232 -24.1 119.0 21.9 4.80 2.56 146.1 4.80 2.56 146.1 4.23 .2.19 147.4Entry Bottom Perf/Side Plate/End Plate 90234 -24.1 119.0 18.2 4.89 2.58 146.1 4.89 2.58 146.1 4.33 2.22 147.4Entry Bottom Perf/Side Plate/End Plate 90231 -24.1 119.0 23.7 4.83 2.59 146.1 4.82 2.59 146.1 4.22 2.20 147.4Side Plate/Top Plate 95617 17.6 0.0 88.0 '4.15 2.60 69.4 4.14 2.58 69.4 3.61 2.22 65.2Side Plate/Top Plate 97693 -49.3 0.0 88.0 4.08 2.60 69.8 4.02 2.56 69.8 3.48 2.13 69.7Closure Plate/Middle Hood 89317 60.2 -85.2 87.0 2.43 2.60 70.1 2.45 2.39 92.5 2.29 2.08 89.3Side Plate/Top Plate 93031 -80.2 -85.2 88.0 4.57 2.62 69.4 4.50 2.57 69.4 4.18 2.30 69.7Top Plate/Inner Hood 85S12 24.1 -30.6 88.0 5.17 2.67 60.6 5.16 2.67 60.6 4.40 2.20 60.5Entry Bottom Perf/Side Plate/End Plate 90230 -24.1 119.0 25.6 4.98 2.68 146.1. 4.98 2.68 146.1 4.34 2.27 147.4116.

This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationEntry Bottom Perf/Side Plate/End Plate 90235 -24.1 119.0 16.3 5.14 2.70 146.1 5.14 2.70 146.1 4.49 2.29 147.4Vane Bank Plate/Entry Bottom Perf/Side 90168 -24.1 119.0 14.5 5.14 2.75 146.1 5.14 2.75 146.1 4.44 2.33 147.4Plate/End PlateSide Plate/Top Plate 91054 80.2 -85.2 88.0 2.68 2.75 66.0 2.59 2.58 92.5 2.50 2.33 89.3Side Plate/Top Plate 99455 -80.2 85.2 88.0 2.67 2.78 65.5 2.56 2.58 65.5 2.52 2.40 89.3Hood Support/Outer Base Plate/Backing Bar 95428 -71.3 0.0 0.0 1.75 2.80 51.2 1.74 2.80 51.2 1.72 2.49 53.8Top Plate/Inner Hood 99104 -24.1 23.9 88.0 5.66 2.83 60.8 5.66 2.82 60.8 5.32 2.67 52.2Hood Support/Middle Base Plate Backing 85723 -39.9 0.0 0.0 1.81 2.84 66.4 1.81 2.74 66.4 1.70 2.36 89.3Bar/Inner HoodSide Plate/Top Plate 85117 -54.0 -54.3 88.0 5.28 2.85 69.4 5.42 2.97 69.4 5.14 2.77 89.3Entry Bottom Perf/Side Plate/End Plate 90229 -24A1 119.0 27.4 5.19 2.85 146.1 5.19 2.85 146.1 4.56 2.41 147.4Side Plate/Brace 87633 79.7 -85.2 31.3 3.40 2.86 123.5 3.51 2.83 92.4 3.45 2.66 89.3Inner Hood/Top Plate 85516 24.1 -23.9 88.0 5.66 2.87 60.6 5.65 2.87 60.6 4.59 2.37 60.5Inner Hood/Top Plate 90897 24.1 -27.8 88.0 5.16 2.90 60.6 5.16 2.90 60.6 4.66 2.45 60.5Outer Cover Plate/Outer Hood 95236 -102.8 -1.0 0.0 5.09 2.91 60.6 5.11 2.92 60.6 4.90 2.68 52.2Outer Cover Plate/Outer Hood 95237 -102.8 1.0 0.0 5.07 2.92 60.6 5.10 2.93 60.6 4.83 2.70 52.2Top Plate/Inner Hood 99130 -24.1 26.8 88.0 5.55 2.92 60.8 5.55 2.91 60.8 5.26 2.78 61.4Hood Support/Inner Hood 99540 32.4 0.0 72.5 5.31 2.93 61.3 5.34 2.93 61.3 4.21 2.23 53.8Top Plate/Inner Hood 99115 -24.1 30.6 88.0 5.71 2.94 60.8 5.75 2.93 60.8 5.27 2.77 52.2Hood Support/Inner Hood 99541 32.0 0.0 74.4 5.29 2.94 61.3 5.30 .2.94 61;3 4.34 2.31 53.8Vane Bank Plate/Side Plate/End Plate 90169 -24.1 119.0 13.1 5.51 2.94 142.0 5.51 2.94 142.0 4.70 2.49 147.4Vane Bank Plate/Side Plate/End Plate 90582 24.1 -119.0 11.6 5.17 2.94 147.8 5.18 2.95 147.8 4.67 2.50 148.6Top Plate/Inner Hood 99132 -24.1 27.8 88.0 5.15 2.95 60.8 5.15 2.94 60.8 4.86 2.78 61.4Outer Cover Plate/Outer Hood 95238 -102.8 2.9 0.0 5.13 2.95 60.6 5.16 2.95 60.6 4.83 2.73 S2.2Outer Cover Plate/Outer Hood 95234 -102.8 -4.9 0.0 5.24 2.97 60.6 5.24 2.97 60.6 5.10 2.73 52.2Outer Cover Plate/Outer Hood 95241 -102.8 4.9 0.0 5.13 2.97 60.6 S.16 2.97 60.6 4.78 2.76 52.2End Plate/Inner Hood 95777 -39.3 115.1 20.5 4.79. 2.98 146.1 4.79 2.98 146.1 4.47 2.53 147.4Tie Bar 137575 17.6 59.8 88.0 2.85 .2.98 65.5 2.91 3.02 65.5 2.63 2.29 89.3Top Plate/Inner Hood 91288 24.1 -26.3 88.0 5.85 2.99 60.6 5.84 2.99 60.6 4.87 2.SO 60.5Tie Bar 138250 17.6 -59.8 88.0 2.88 2.99 69.4 2.90 2.95 92.5 2.64 2.55 89.3117 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationRPS nodes located off weld with 3 < SR-a < 4Brace 37811 79.6 85.5 75.8 4.66 3.32 134.3 4.66 3.31 134.3 3.83 2.84 147.4Inner Hood 70582 31.4 -36.1 77.1 6.72 3.38 60.6 6.71 3.38 60.6 5.67 2.79 60.5Middle Hood 30488 -64.8 24.8 67.6 7.27 3.68 59.5 7.25 3.68 59.5 5.57 2.76 56.4Inner Hood 70627 31.8 -16.2 75.4 7.92 3.91 60.6 7.92 3.91 60.6 6.73 3.36 53.8RPS nodes located on weld with 3 < SR-a <4Outer End Plate/Outer Hood 99213 -97.9 -69.4 58.4 5.74 3.02 69.8 5.82 3.05 69.8 5.62 2.80 69.7Side Plate/Top Plate 91055 81.1 -85.2 88.0 3.04 3.02 69.5 2.92 2.81 92.5 2.81 2.59 89.3Outer End Plate/Outer Hood 100731 -101.7 -63.6 27.1 5.67 3.03 91.6 5.34 2.70 92.5 5.49 2.71 89.3Hood Support/Inner Hood 95645 -36.5 0.0 48.8 5.68 3.04 49.6 5.68. 3.04 49.6 4.73 2.47 44.5Vane Bank Plate/Side Plate/Outer End Plate 90812 87.0 85.2 11.6 -3.94 3.15 123.5 4.06 3.22 123.5 3.77 2.82 89.3Side Plate/Top Plate 103080 49.6 -108.6 88.0 3111 3.17 92.5 3.21 3.07 92.5 2.39 2.05 89.3Hood Support/Outer Hood 85769 -98.1 -28.4 57.1 6.00 3.20 69.4 5.94 3.17 69.4 5.44 2.90 69.7Side Plate/Top Plate 101600 -17.6 -119.0 88.0 1.80 3.23 69.8 1.79 3.18 69.8 1.69 2.93 89.3Hood Support/Inner Hood 90431 -36.8 59.5 46.9 5.89 3.23 49.6 5.90 3.23 49.6 4.75 2.57 52.2MiddleHood/Top Plate 90947 55.6 -27.9 88.0 5.67 3.24 52.1 5.74 3.26 52.1 5.25 2.76 61.4Entry Bottom Perf/Side Plate/Outer End Plate 90823 87.0 85.2 .29.3 5.88 3.30 96.9 5.94 3.28 96.9 4.78 2.50 89.2Side Plate/Brace 89650 80.6 85.2 75.8 4.66 3.33 134.3 4.67 3.32 134.3 3.81 2.79 147.4Hood Support/Middle Hood 98462 63.8 0.0 72.5 6.11 3.33 61.2 6.12 3.34 61.2 6.04 3.38 69.9Hood Support/Inner Hood 95637 -38.3 0.0 32.9 632 3.36 40.3 6.73 3.36 40.3 4.93 2.46 44.5Outer End Plate/Outer End Plate 95264 95.9 72.4 0.0 6.50 3.37 123.5 6.59 3.37 123.5 5.91 3.18 89.3Thin Vane Bank Plate/Hood Support/Outer 98950 -87.0 -28.4 0.0 3.57 3.40 52.1 3.59 3.47 52.1 3.41 3.72 49.5Base PlateOuter Cover Plate/Outer Hood 95251 -102.8 12.7 0.0 5.72 3.43 60.6 5.74 3.43 60.6 5.25 3.24 52.2Outer End Plate/Outer Hood 94570 100.6 65.3 39.3 6.86 3.44 123.5 6.99 3.50 92.5 5.92 2.95 89.2End Plate/End Plate Ext 96132 -31.5 117.2 0.0 6.25 3.44 142.0 6.25 3.44 142.0 5.07 2.76 145.5Hood Support/Outer Hood 91741 -99.8 -28.4 45.3 6.69 3.46 52.1 6.72 3.47 52.1 7.51 3.84 52.2End Plate/End Plate Ext 96111 -32.7 116.9 0.0 6.48 3.48 142.0 6.47 3.48 142.0 5.23 2.79 145.5Hood Support/Inner Hood 95821 -32.8 -59.5 70.5', 6.73 3.61 60.6 6.73 3.61 60.6 6.83 3.69 60.5118 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationClosure Plate/Middle Hood 91590 -68.7 85.2 42.9 6.72 3.67 69.8 6.62 3.64 69.8 5.67 3.05 69.7Middle Base Plate/Backing Bar/Inner Hood 84197 -39.9 -108.6 0.0 1.80 3.71 52.1 1.79 3.62 52.1 1.73 2.97 69.7Hood Support/Inner Hood 99514 39.3 0.0 21.0 7.07 3.71 44.1 7.04 3.71 44.1 6.00 3.07 48.0Entry Bottom Perf/Side Plate/End Plate 90226 -24.1 119.0 33.0 6.11 3.72 146.1 6.11 3.72 146.1 5.39 3.15 147.4Hood Support/Middle Hood 98477 68.9 0.0 40.9 7.59 3.74 53.1 7.59 3.75 53.1 6.30 3.16 50.0Hood Support/Middle Base Plate/Backing 90468 -39.9 59.5 0.0 2.03 3.77 69.8 2.03 3.75 65.5 1.90 3.34 89.3Bar/Inner HoodOuter End Plate/Outer Hood 99185 -95.7 -72.7. 70.1 7.48 3.79 69.8 7.38 3.73 69.8 6.61 3.40 69.7Top Plate/Inner Hood 99156 -24.1 20.0 88.0 7.58 3.85 60.8 7.57 3.84 60.8 6.94 3.59 52.2Vane Bank Plate/Hood Support/Middle Base Plate 98968 55.6 -54.3 0.0 2.13 3.87 .42.2 2.12 3.85 40.5 2.03 3.21 89.3Side Plate/Brace 88745 -85.7 -85.2 53.5 7.39 3.91 69.8 7.18 3.59 69.8 6.50 3.29 89.3Outer End Plate/Outer Hood 94561 102.4 62.5 14.8 7.28 3.96 123.5 7.33 3.88 123.5 6.65 3.31 89.2Hood Support/Outer Base Plate/Backing Bar 100204 71.3 54.3 0.0 4.16 3.97 147.8 4.17 3.96 147.8 4.02 3.27 53.8Hood Support/Middle Hood 99416 63.8 54.3 72:5 7.63 3.97 53.1 7.67 3.97 53.1 8.17 4.17 60.5Vane Bank Plate/Hood Support/Inner Base Plate 85191 24.1 -59.5 0.0 1.82 4.00 52.2 1.77 4.03 92.5 1.67 3.25 89.3Non weld RPS nodes with SR-P < 3Inner Side Plate 37229 3.1 119.0 0.5 2.22 16.78 70.8 2.22 16.16 69.8 2.20 15.56 89.3RPS nodes located on weld with SR-P < 3USR/Support/Seismic Block 113554 =6.9 -122.3 -9.5 1.25 6.15 14.2 1.25 6.12 14.2 1.27 6.48 16.9Side PlateExt/Inner Base Plate 94143 16.3 119.0 0.0 1.31 9.65 101.0 1.32 9.95 92.4 1.29 8.02 89.3Tie Bar 141275 49.3 108.1 88.0 1.45 5.40 91.1 1.45 5.36 92.5 1.38 4.11 89.3Top Thick Plate/Side Plate/Closure Plate/Top Plate 91558 -47.1 -108.6 88.0 1.56 5.32 195.5 1.57 5.33 191.3 1.58 5.42 190.8Inner Side Plate/Inner Base Plate 99200 -2.3 -119.0 0.0 1.67 7.67 69.8 1.65 7.33 69.8 1.67 6.97 89.3Side Plate/Top Plate 91215 17.6 119.0 88.0 1.78 3.46 69.8 1.78 3.31 92.5 1.62 2.40 89.3Hood Support/Middle Base Plate/Backing 88639 39.9 0.0 0.0 1.79 3.42 40.5 1.78 3.36 40.5 1.70 2.65 89.2Bar/Inner HoodVane Bank Plate/Hood Support/Inner Base Plate 99487 -24.1 59.5 0.0 1.81 4.38 44.9 1.76 3.89 92.5 1.73 3.96 53.7Outer Cover Plate/Outer Hood 94498 102.8 -58.1 0.0 1.91 6.41 10.5 1.91 6.43 10.5 1.88 5.76 10.9Vane Bank Plate/Hood Support/Inner Base Plate 91888 -24.1 0.0 0.0 2.17 4.33 45.5 2.17 3.97 92.5 2.04 3.36 89.3119 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary InformationTie Bar 141237 25.0 108.1 88.0 2.32 6.62 70.3 2.36 6.72 92.4 2.24 5.09 89.3USR/Seismic Block/Support 113508 -122.1 10.2 -9.5 2.38 10.42 52.1 2.38 10.36 52.1 2.28 9.31 89.3Closure Plate/Inner Hood 95172 28.8 -108.6 87.0 2.38 4.21 66.4 2.32 3.99 92.5 1.90 2.41 89.3Vane Bank Plate/Hood Support/Outer Base Plate 98956 -87.0 28.4 0.0 2.65 4.02 50.1 2.60 3.97 50.1 2.56 3.94 60.5Hood Support/Outer Base Plate/Backing Bar 95000 71.3 -54.3 0.0 2.76 4.47 147.8 2.77 4.50 147.8 2.66 3.89 89.3.Submerged Skirt/Drain Channel 95139 91.0 -76.7 -100.0 2.89 4.73 51.5 2.89 4.74 51.5 2.72 3.78 89.3Tie Bar .140202 -80.8 84.7 88.0 2.93 4.46 65.5 2.81 4.14 65.5 2.66 3.65 89.3Tie Bar 140238 -56.4 84.7 88.0 2.94 6.42 69.4 2.96 6.57 69.4 3.07 6.75 89.3120 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information7. ConclusionsA stress evaluation of the NMP2 steam dryer with the modifications described in Section 5.and summarized in Table 10 has been carried out using acoustic loads collected at EPU (115%CLTP) conditions. The analysis calculates the stresses arising when the steam dryer is subjectedto acoustic loads inferred from strain gage measurements on the main steam lines and acalibrated acoustic circuit model (ACM, Rev. 4.1) that uses these measurements to obtain theacoustic loads on the dryer. The ANSYS FEA package is then used to acquire the dryer stressresponse resulting from these acoustic loads and the stress results post-processed to obtain thelimiting alternating stress ratios. The results account for all biases and uncertainties identifiedfor both the ACM Rev. 4.1 and the FEA harmonic analysis.The stress evaluation shows that the limiting alternating stress ratio on the dryer with allmodifications implemented is SR-a=2.49 and occurs on the inner vane bank welded sideplate/end plate junction. The limiting stress ratio due to a maximum stress is SR-P=1.25. Thesestress estimates represent the limiting Values after all frequency shifts in the +/-10% frequencyrange are considered and all end-to-end bias and uncertainties have been imposed.These stress ratios qualify the steam dryer for EPU operation.During power ascension testing NMP identified two off-normal loading conditions associatedwith the operational lineup of the RCIC system that create either a 92.5 Hz (RCIC steam linedrains isolated) or a 89.25 Hz content (RCIC steamline isolated)on the MSL B. Therefore a realtime analysis is performed using both estimated and measured EPU loads from the test data. Theresulting limiting alternating stress ratio is shown to be SR-a=2.39 with 92.5 Hz content andSR-a=2.05 with 89.25 Hz content. In each case the required stress margin is met.121 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information8. References1. Continuum Dynamics, Inc. (2011) Stress Evaluation of Nine Mile Point Unit 2 SteamDryer Using ACM Rev. 4.1 Acoustic Loads. C.D.I. Report No.11-04P (Proprietary),Rev. 0, May.2. Continuum Dynamics, Inc. (2010) Design and Stress Evaluation of Nine Mile Point Unit2 Steam Dryer Modifications for EPU Operation. C.D.I. Report No.10-12P(Proprietary), July.3. ASME Boiler and Pressure Vessel Code,Section III, Subsection NG (2007).4. Continuum Dynamics, Inc. (2011) ACM Rev. 4.1: Methodology to Predict Full ScaleSteam Dryer Loads from In-Plant Measurements (Rev. 3). C.D.I. Report No.10-09P(Proprietary), November.5. Continuum Dynamics, Inc. (2012) Acoustic and Low-Frequency Hydrodynamic Loads at115% CLTP Target Power Level on Nine Mile Point Unit 2 Steam Dryer to 250 Hz UsingACMRev. 4.1 (Rev. 0). C.D.I. Report No.12-20P (Proprietary), September.6. Continuum Dynamics, Inc. (2012) Stress Evaluations of Nine Mile Point Steam DryerModifications. C.D.I. Technical Memo 12-03, Rev. 0, January.7. Continuum Dynamics, Inc. (2011) Sub-Modeling in the Nine Mile Point Unit 2 SteamDryer, Rev. 0. C.D.I. Report No.11-03P (Proprietary), June.8. Continuum Dynamics, Inc. (2007) Methodology to Predict Full Scale Steam Dryer Loadsfrom In-Plant Measurements, with the Inclusion of a Low Frequency HydrodynamicContribution. C.D.I. Report No.07-09P (Proprietary).9. Continuum Dynamics, Inc. (2005) Methodology to Determine Unsteady PressureLoading on Components in Reactor Steam Domes (Rev. 6). C.D.I. Report No. 04-09(Proprietary).10. Continuum Dynamics, Inc. (2010) Stress Assessment of Nine Mile Point Unit 2 SteamDryer Using the Acoustic Circuit Model Rev. 4.1. C.D.I. Report No. 10-1 1P(Proprietary), June.11. Continuum Dynamics, Inc. (2010) Acoustic and Low-Frequency Hydrodynamic Loads atCLTP Power Level on Nine Mile Point Unit 2 Steam Dryer to 250 Hz Using ACM Rev.4.1 (Rev. 2). C.D.I. Report No. 10-1OP (Proprietary), January.12. ANSYS, Release 10.0 Complete User's Manual Set, (http://www.ansvs.com).13. Continuum Dynamics, Inc. (2007) Response to NRC Request for Additional Informationon the Hope Creek Generating Station, Extended Power Uprate. RAI No. 14.110.14. Continuum Dynamics, Inc. (2008) Stress Assessment of Hope Creek Unit 1 Steam DryerBased on Revision 4 Loads Model, Rev. 4. C.D.I. Report No.07-17P (Proprietary).15. Press, W.H., et al., Numerical Recipes. 2 ed. 1992: Cambridge University Press.16. Structural Integrity Associates, Inc. (2010) Flaw Evaluation of Indications in the NineMile Point Unit 2 Steam Dryer Vertical Support Plates Considering Extended PowerUprate Flow Induced Vibration Loading (Rev. 0). SIA Calculation Package No.1000814.401, July.17. Continuum Dynamics, Inc. (2009) Stress Assessment of Nine Mile Point Unit 2 SteamDryer at CLTP and EPU Conditions, Rev. 1. C.D.I. Report No.09-26P (Proprietary),December.122 This Document Does Not Contain Continuum Dynamics, Inc. Proprietary Information18. Structural Integrity Associates, Inc. (2008) Flaw Evaluation and Vibration Assessment ofthe Nine Mile Point Unit 2 Steam Dryer for Extended Power Uprate OperatingConditions. Report No. 0801273.401.19. Continuum Dynamics, Inc. (2008) Stress Assessment of Browns Ferry Nuclear Unit 1Steam Dryer, Rev. 0. C.D.I. Report No.08-06P (Proprietary).20. O'Donnell, W.J., Effective Elastic Constants For the Bending of Thin Perforated PlatesWith Triangular and Square Penetration Patterns. ASME Journal of Engineering forIndustry, 1973. 95: p. 121-128.21. de Santo, D.F., Added Mass and Hydrodynamic Damping of Perforated Plates VibratingIn Water. Journal of Pressure Vessel Technology, 1981. 103: p. 175-182.22. Idel'chik, I E. and E. Fried, Flow Resistance, a Design Guide for Engineers. 1989,Washington D.C.: Taylor & Francis. pg. 260.23. Continuum Dynamics, Inc. (2007) Dynamics of BWR Steam Dryer Components. C.D.I.Report No. 07-1iP.24. U.S. Nuclear Regulatory Commission (2007) Comprehensive Vibration AssessmentProgram for Reactor Internals During Preoperational and Initial Startup Testing.Regulatory Guide 1.20, March.25. Weld Research Council (1998) Fatigue Strength Reduction and Stress ConcentrationFactors For Welds In Pressure Vessels and Piping. WRC Bulletin 432.26. Pilkey, W.D., Peterson's Stress Concentration Factors, 2nd ed. 1997, New York: JohnWiley. pg. 139.27. Lawrence, F.V., N.-J. Ho, and P.K. Mazumdar, Predicting the Fatigue Resistance ofWelds. Ann. Rev. Mater. Sci., 1981. 11: p. 401-425.28. General Electric (GE) Nuclear Energy, Supplement I to Service Information Letter (SIL)644, "B WR/3 Steam Dryer Failure, "September 5. 2003.29. Tecplot, Inc. (2004) Documentation: Tecplot User's Manual Version 10 Tecplot, Inc.,October.30. Continuum Dynamics, Inc. (2009) Compendium of Nine Mile Point Unit -2 Steam DryerSub-Models Away From Closure Plates C.D.I. Technical Note No.09-16P (Proprietary),August.31. Structural Integrity Associates, Inc. (2009) Nine Mile Point Unit 2 Steam Dryer ClosurePlates Analysis Results. SIA Letter Report No. 0900895.401 Revision 0, August 21.32. Westinghouse (2011) NMP2 Steam Dryer Modifications and Repairs. FCN-MODS-NMP2-11, Rev. 1.33. Continuum Dynamics, Inc. (2012) Limit Curves with ACM Rev. 4.1 for the 115% PowerLevel Basis with 92.5 Hz Peak at Nine Mile Point Unit 2 (Rev. 0). C.D.I. Technical NoteNo. 12-28 (Proprietary). September.34. Continuum Dynamics, Inc. (2012) Real Time Monitoring of the Nine Mile Point Steamduring Power Ascension. C.D.I. Technical Note No.12-17P (Proprietary). June.123 ATTACHMENT 3AFFIDAVIT FROM CONTINUUM DYNAMICS, INCORPORATED (CDI)JUSTIFYING WITHHOLDING PROPRIETARY INFORMATION(CDI REPORT NO.12-18P)Nine Mile Point Nuclear Station, LLCOctober 26, 2012 410 Continuum Dynamics, Inc.(609) 538-0444 (609) 538-0464 fax 34 Lexington Avenue Ewing, NJ 08618-2302AFFIDAVITRe: C.D.I. Report No.12-18P "Stress Evaluation of Nine Mile Point Unit 2Steam Dryer at 115% CLTP," Revision 0I, Alan J. Bilanin, being duly sworn, depose and state as follows:1. I hold the position of President and Senior Associate of Continuum Dynamics, Inc. (hereinafterreferred to as C.D.I.), and I am authorized to make the request for withholding from PublicRecord the Information contained in the document described in Paragraph 2. This Affidavit issubmitted to the Nuclear Regulatory Commission (NRC) pursuant to 10 CFR 2.390(a)(4) basedon the fact that the attached information consists of trade secret(s) of C.D.I. and that the NRCwill receive the information from C.D.I. under privilege and in confidence.2. The Information sought to be withheld, as transmitted to Constellation Energy Group asattachment to C.D.I. Letter No. 12115 dated 17 October 2012, C.D.I. Report No.12-18P"Stress Evaluation of Nine Mile Point Unit 2 Steam Dryer at 115% CLTP," Revision 0. Theproprietary information is identified by its enclosure within pairs of double square brackets ("[[]]"). In each case, the superscript notation (3) refers to Paragraph 3 of this affidavit thatprovides the basis for the proprietary determination.3. The Information summarizes:(a) a process or method, including supporting data and analysis, where prevention of its use byC.D.I.'s competitors without license from C.D.I. constitutes a competitive advantage overother companies;(b) Information which, if used by a competitor, would reduce his expenditure of resources orimprove his competitive position in the design, manufacture, shipment, installation,assurance of quality, or licensing of a similar product;(c) Information which discloses patentable subject matter for which it may be desirable toobtain patent protection.The information sought to be withheld is considered to be proprietary for the reasons set forthin paragraphs 3(a), 3(b) and 3(c) above.4. The Information has been held in confidence by C.D.I., its owner. The Information hasconsistently been held in confidence by C.D.I. and no public disclosure has been made and it isnot available to the public. All disclosures to third parties, which have been limited, have beenmade pursuant to the terms and conditions contained in C.D.I.'s Nondisclosure SecrecyAgreement which must be fully executed prior to disclosure.

5. The Information is a type customarily held in confidence by C.D.I. and there is a rational basistherefore. The Information is a type, which C.D.I. considers trade secret and is held inconfidence by C.D.I. because it constitutes a source of competitive advantage in thecompetition and performance of such work in the industry. Public disclosure of theInformation is likely to cause substantial harm to C.D.I.'s competitive position and foreclose orreduce the availability of profit-making opportunities.I declare under penalty of perjury that the foregoing affidavit and the matters stated therein are true andcorrect to be the best of my knowledge, information and belief.Executed on this __ PA__ day of 0o 2012.Alan J. Bilaniny/Q !Continuum Dynar4cs, Inc.Subscribed and sworn before me this day: Zý2 /.c~,oEILEEN P BURMEISTERNOTARY PUBLICSTATE OF NEW JERSEYMy Commission Expires May 06,2017