Status of ITER Neutronicsand CAD/MCNPDevelopmentMohamed Sawanfor UW-Madison TeamPaul Wilson, Tim Tautges (SNL),Greg Sviatoslavsky, Brian KiedrowskiFusionTechno lo gyInstitut eITER TBM MeetingUCLAMay 10-11 2006M. Sawan ITER TBM MeetingMay 10-11, 20062• ITER first magnetic fusion facilitywhich:– will produce significant fusion power– requires nuclear licensing• According to French regulation ITER– will be classified as a nuclear Installationcalled “Installation Nucléaire de Base”(INB) due to the expected tritiuminventory and waste generation during thelifetime of ITER• The aim of ITER Organization is to:– construct and operate such first-of-a-kindnuclear installation satisfying the demandsand interests of the user community and offunding partnersNeutronic Analysis Service for ITERM. Sawan ITER TBM MeetingMay 10-11, 20063• Extensive neutronics calculations and analyses in ITER are required to– ensure that existing, modified, or proposed structure, system, or componentdesigns will meet technical and functional requirements– demonstrate capability of safe operation– assess maintaining, repairing, replacing or modifying components– provide required baseline for access, repository and waste management ofcomponents• Neutronics calculations and analyses shall conform to the ITERManagement and Quality Program (MQP) that establishes the overallframework for the execution of the ITER Project• This implies the availability of:– Adequate modelling tools which would reduce turnaround time between CAD-based design and design changes and analysis.– Well documented QA procedures for neutronic work.– Database systemRole of Neutronic Analyses in ITERM. Sawan ITER TBM MeetingMay 10-11, 20064US Neutronics Support Areas:Global model, diagnostics, TBM, FW/shieldM. Sawan ITER TBM MeetingMay 10-11, 20065Previous Work on CAD Interfacewith 3D Neutronics• Translation-based approaches– Tsige-Tamirat et al., FZK– Manson, Raytheon– Van Riper, White Rock Science– Wu et al., Hefei, China+ Speed– Setup effort• Direct CAD evaluation– Franke et. al, SNL+ Setup effort– SpeedM. Sawan ITER TBM MeetingMay 10-11, 20066CAD-Based MCNP(X)• Use Common Geometry Module (CGM) tointerface MCNPX directly to CAD & othergeometry data– Previous efforts found CAD-based raytracing to be too slow (20-50x)– Implement ray-tracing approximations in CGM to reducecalls to exact CAD function• Benefits:– Dramatically reduce turnaround timefrom CAD-based design changes– No translation to MC geometry representation• Removes limitation on surface types• Improves robustness by using same engine for CAD and MCNP– Can handle 3D models not supported in MCNPCGMCAD VoxelsMCNPXMCNPXNativeGeometry (Other)M. Sawan ITER TBM MeetingMay 10-11, 20067MCNPX/CGM Example ARIES CompactStellerator• High-degree NURBS geometry from curves/surfacesfit to Fourier seriesIBOBθTIBOBθTM. Sawan ITER TBM MeetingMay 10-11, 20068CPU Time vs. MCNPX• MCNPX – original code• BB – Axis-oriented bounding box• OBB – Oriented bounding box• Sorted BB – Grid-sorted BB• Dist limit – transport distance-limited• Facet-only: No ACIS ray intersection– (less accurate, MUCH faster)3cyls0102030405060MCNPXBBSort BBSort BB, dist lmtSort OBBSort OBB, dist lmtOBB, Facet-onlyTime FactorCobalt051015202530MCNPXBBSort BBSort BB, dist lmtSort OBBSort OBB, dist lmtOBB, Facet-onlyTime Factor4.33.0!23.512.3!+M. Sawan ITER TBM MeetingMay 10-11, 20069CAD PROCESSINGCAD PROCESSINGCATIAfileCATIA STEPfileCUBITACISfileMCNPX/CGMtranslationdata preparation:model &analysis “imprint” surfaces “merge” matingsurfacesM. Sawan ITER TBM MeetingMay 10-11, 200610Imprint & Merge ProcessImprint & Merge ProcessVolume AVolume BVolume AVolume B1. PRIOR to Imprint, top of Volume Bmade up of one surface2. Following IMPRINT, top of Volume Bmade up of three surfaces3. Following MERGE, top of Volume B made up of twosurfaces plus one surface shared with Volume AM. Sawan ITER TBM MeetingMay 10-11, 200611CAD Issues Requiring CAD Issues Requiring ““RepairRepair””• Overlapping Volumes (i.e.: clashes)• Mating surfaces not contacting• Slight “Misalignment”– Imprint generates ultra thin surfaces– Doesn’t always require repairComplex Surface DefinitionM. Sawan ITER TBM MeetingMay 10-11, 200612Examples of Typical CAD IssuesExamples of Typical CAD Issuesand Typical Repairsand Typical RepairsM. Sawan ITER TBM MeetingMay 10-11, 200613Action - Volumes trimmed to contact onlyOverlapping VolumesOverlapping VolumesIssue – Overlapping VolumesM. Sawan ITER TBM MeetingMay 10-11, 200614Action – Edit geometry toestablish proper contactMating Surfaces Not ContactingMating Surfaces Not ContactingIssue – No ContactM. Sawan ITER TBM MeetingMay 10-11, 200615Action – Edit geometry to correct misalignmentMisalignmentMisalignmentIssue – misalignment … … causes imprint difficultyand therefore no mergeM. Sawan ITER TBM MeetingMay 10-11, 200616Action – MAY require recreating volumeEdges cross at this pointAction – MAY require recreating volumeIssue – Slight Edge MisalignmentMisalignmentMisalignmentEdges cross at this pointM. Sawan ITER TBM MeetingMay 10-11, 200617Complex Surface DefinitionComplex Surface DefinitionAction – Recreategeometry and/or“Unify” neighboringvolumes into a singlevolume.Issue – definition ofneighboring complexsurfaces differ slightly,preventing surfacesfrom mergingM. Sawan ITER TBM MeetingMay 10-11, 200618Complex Surfaces & MisalignmentComplex Surfaces & MisalignmentIssue – Misalignmentalong curvedsurfacesM. Sawan ITER TBM MeetingMay 10-11, 200619Distribution of Repair EffortsDistribution of Repair Efforts40%40%MisalignmentMisalignment50% Complex50% ComplexSurfaceSurfaceDefinitionDefinition10% Overlapping Volumes10% Overlapping Volumes& Non-contact& Non-contactM. Sawan ITER TBM MeetingMay 10-11, 200620Improving the ProcessImproving the Process➤Direct Link to CATIA (or appropriate modeler)data – eliminating possible translation issues➤Work with original ITER data – simplificationprocess may have introduced errors➤Tighten design process to minimize “designer-introduced” issues➤Leverage prior work via configuration control -allowing future model revisions to address onlythose area that have changedM. Sawan ITER TBM MeetingMay 10-11, 200621MCNP(X)-CGMDevelopment Plan & Progress• Upgrade to newest versions of MCNP(X)• Upgrade to MCNPX v2.5.0 complete–