.. _sec-mavric-shift: MAVRIC-Shift: Radiation Shielding Analysis Sequence with Shift ============================================================== Introduction ------------ MAVRIC-Shift integrates the Shift fixed-source Monte Carlo solver into the MAVRIC shielding sequence. MAVRIC continues to prepare problem-dependent cross sections and, for CADIS and FW-CADIS, uses Denovo to construct an importance map and biased source. Shift performs the final Monte Carlo transport calculation in place of Monaco. Main enhancement with MAVRIC-Shift is support for parallel processing which is enabled for both Deonovo and Shift. This section describes the MAVRIC-Shift implementation in SCALE 6.3. Input requirements ------------------ Input requirements for MAVRIC-Shift are designed to match MAVRIC with a few exceptions that are mentioned below. Users should be able to change the sequence name from ``=mavric`` to ``=mavric-shift`` and tend to any unsupported features and/or parameters to convert. their model to MAVRIC-Shift as seen in the example below. Select the Monte Carlo engine with the sequence name: .. code-block:: scale :caption: MAVRIC sequence selection =mavric My shielding calculation with Monaco =mavric-shift My shielding calculation with Shift MAVRIC-Shift retains the MAVRIC block layout and most input syntax. Changing the sequence name is sufficient only when every source, tally, response, and importance map option used by the model is supported by the Shift interface. An unsupported filter or control can change the physical problem; do not remove one only to make the input execute. It is highly recommended to use Fulcrum to validate MAVRIC-Shift models when converted from MAVRIC. The shared definitions, sources, tallies, parameters, and biasing blocks are defined in :numref:`sec-module.monaco`. MAVRIC-specific importance map input is defined in :numref:`keywords-importance` and :numref:`denovo-op`. Sequence capabilities --------------------- MAVRIC-Shift supports the principal MAVRIC calculation modes shown in the table below. .. tabularcolumns:: |\Yl{0.28}|\Yl{0.32}|\Yl{0.40}| .. list-table:: Supported MAVRIC-Shift capabilities :name: tab-mavric-shift-supported-capabilities :header-rows: 1 :widths: 28 32 40 :class: longtable * - Capability - MAVRIC input - MAVRIC-Shift behavior * - Analog forward transport - Omit the ``importanceMap`` block - Shift performs the final Monte Carlo calculation without a Denovo importance map calculation. * - CADIS - ``importanceMap`` and ``adjointSource`` - Denovo calculates the adjoint flux; Shift uses the biased source and weight windows. * - FW-CADIS - ``respWeighting`` or ``fluxWeighting`` - Denovo calculates the forward and adjoint fluxes; Shift uses the resulting biased source and weight windows. * - Multigroup and continuous-energy transport - Input library name, ``library``, or ``ceLibrary`` - Both final-transport energy modes are supported. * - Neutron, photon, and coupled transport - ``neutron`` and ``photon`` - Neutron-only, photon-only, and coupled neutron--photon transport are supported. * - Region tallies - ``regionTally`` - Flux, energy bins, supported responses, uncertainty, and figure of merit (FOM) are reported. * - Mesh tallies - ``meshTally``, ``gridGeometryID``, and ``cylGeometryID`` - Flux, energy bins, supported responses, uncertainty, FOM, and ``*.3dmap`` postprocessing are supported. * - Response definitions - ``response`` and ``doseData`` - User-defined responses and supported dose and reaction responses are supported. * - Source material filter - ``mixture`` in a source definition - The source can be restricted to a material mixture. * - Adjoint source - ``adjointSource``, ``boundingBox``, and ``locationID`` with ``responseID`` - The adjoint source can be defined over a volume for CADIS or FW-CADIS, but point adjoint sources are not supported. * - Parallel final transport - Execution option; no MAVRIC input keyword - Shift can use MPI when the installed SCALE build includes MPI. For CADIS and FW-CADIS, Denovo performs the deterministic calculation and Shift consumes the resulting source biasing and weight window data. Supported tally summaries include the mean, standard deviation, relative uncertainty, and figure of merit (FOM). Limitations relative to MAVRIC-Monaco ------------------------------------- MAVRIC-Shift does not support every Monaco input. Use MAVRIC-Monaco, or revise the model, when it requires an entry listed in the table below. It is highly recommended to use Fulcrum for validation of models when converting a MAVRIC-Monaco model to MAVRIC-Shift model to identify unsupported features. .. tabularcolumns:: |\Yl{0.28}|\Yl{0.34}|\Yl{0.38}| .. list-table:: MAVRIC-Monaco input not supported by MAVRIC-Shift :name: tab-mavric-shift-unsupported-capabilities :header-rows: 1 :widths: 28 34 38 :class: longtable * - Capability - Monaco input - MAVRIC-Shift behavior and guidance * - Point-detector tallies - ``pointDetector`` - Unsupported. Use MAVRIC-Monaco when a point estimate is required. * - CAAS KENO-VI fission-source import - ``meshSourceFile``, ``fissPhotonZaid``, ``fissions``, and ``nu-bar`` - Unsupported. Use MAVRIC-Monaco or consider using a Watt fission distribution. * - Tally time bins - ``timeBoundsID`` - Unsupported. Use MAVRIC-Monaco for time-dependent tally bins. * - Source unit and region filters - ``unit`` and ``region`` - Unsupported. The source ``mixture`` filter is supported. * - Source spatial distributions and scaling - ``xDistributionID``, ``yDistributionID``, ``zDistributionID``, ``rDistributionID``, ``xScaleDist``, ``yScaleDist``, ``zScaleDist``, and ``rScaleDist`` - Unsupported. Use only source distributions accepted by MAVRIC-Shift. * - Source direction, axis, rotation, and resampling - ``dDistributionID``, ``dScaleDist``, ``direction``, ``cylinderAxis``, ``rotate``, and ``allowResampling`` - Unsupported. Use MAVRIC-Monaco if these cards define the physical source. * - Explicit source-sampling bias - ``biasedStrength`` - Unsupported. Use MAVRIC-Monaco if needed * - Mesh-source export - ``meshSourceSaver`` - Unsupported. MAVRIC-Shift cannot save the defined source as a Monaco mesh-source file. * - Region tally filters - ``mixture`` - Unsupported. Use an unfiltered region tally or MAVRIC-Monaco. * - Mesh tally filters - ``unit``, ``region``, and ``mixture`` - Unsupported. Use an unfiltered Cartesian mesh tally or MAVRIC-Monaco. * - Mesh tally detail modes - ``weightless`` and ``saveRespDetails`` - Unsupported. Use the available Shift mesh tally output or MAVRIC-Monaco. * - Adjoint-source location, unit, and region filters - ``locationID``, ``unit``, and ``region`` - Unsupported. Define a supported ``boundingBox`` adjoint source or use MAVRIC-Monaco. * - Adjoint-source material filter - ``mixture`` - Unsupported. * - General library-derived responses - ``MT``, ``nuclide``, and ``material`` - Partially supported. Material-based responses are not supported. Use a supported response, define the response explicitly, or use MAVRIC-Monaco. * - Reuse of deterministic flux files - ``forwardFluxes`` and ``adjointFluxes`` - Unsupported. MAVRIC-Shift must calculate the required Denovo fluxes. * - Importance-map source and weight overrides - ``subCells``, ``mapMultiplier``, and ``saveExtraMaps`` - Unsupported. Use the MAVRIC-Shift importance map construction. * - Legacy Denovo multigroup solver selectors - ``partUpscatter``, ``krylovType``, ``eigenSolver``, ``multiGSolver``, ``mgSettings``, ``upGroupSolver``, ``maxItersMG``, and ``toleranceMG`` - Unsupported. Remove the legacy selectors or use MAVRIC-Monaco. * - User-supplied Monte Carlo biasing - ``read biasing`` - Unsupported. Use analog transport, CADIS, or FW-CADIS. * - Run-time, particle-age, and weight-window controls - ``maxMinutes``, ``nMaxAge``, ``pMaxAge``, ``allowShortImpMap``, ``noCheckAtBirth``, and ``voidAllRegions`` - Unsupported. Select histories and supported stopping controls instead. * - Geometry map generation controls - ``make3dMaps``, ``make3dMap``, ``makeCylMaps``, and ``makeCylMap`` - Unsupported. This does not prevent ``*.3dmap`` processing of supported Cartesian mesh-tally results. * - Creating chart files - ``makeChart`` and ``makeCharts`` - Unsupported. Use MAVRIC-Monaco if needed. * - Response output control - ``lessOutput`` - Unsupported. * - Distribution fine-tuning and controls - ``trueCDF``, ``biasedPDF``, ``biasedCDF``, ``weight``, ``importance``, ``runSampleTest``, and ``runSampleTests`` - Unsupported. Use MAVRIC-Monaco if needed. * - Monaco six-check tally suite - Automatic output; ``noStatChecks`` disables it in Monaco - Not implemented. MAVRIC-Shift reports tally uncertainty and FOM. MAVRIC-Shift calculates and reports FOM values. It does not reproduce the six statistical checks printed for Monaco point and region tallies. Transport engine selection -------------------------- As of SCALE 6.3.4, we recommend using MAVRIC-Shift when its supported source and tally definitions cover the analysis and parallel Shift transport is useful. Use MAVRIC-Monaco when the model depends on a missing feature, especially point detectors, time dependence, or the SCALE 6.3 CAAS mesh source workflow. Solver comparisons require equivalent physical models. Use the same nuclear data, geometry, material temperatures, source strength and distributions, responses, tally bounds, variance reduction targets, and stopping criteria. The two Monte Carlo engines do not share random number streams, so tally values should be compared statistically, not for exact equality. Parallel execution ------------------ Monaco particle transport in MAVRIC is serial. Denovo and Shift final transport can run in parallel with an MPI-enabled SCALE installation. The code output reports used executable, process count, histories, CPU time, wall time, uncertainty, and FOM for any performance comparison. A serial SCALE installation exercises MAVRIC-Shift functionality but cannot validate MPI scaling. Users can execute a parallel job by providing ``-N`` flag, followed by number of processors desired and optionally provide a machine file via ``-M``. .. note:: An analog model without an ``importanceMap`` block can be run in parallel as: :: scalerte –N 4 –M mach mavric-shift.inp .. important:: If a variance-reduction method is enabled via ``importanceMap`` then number of processors should be the product of ``xblocks``, ``yblocks``, and ``numSets`` when running a MAVRIC-Shift model n parallel. One SCALE 6.3 development study used a simplified continuous-energy spent-fuel cask model. In the high-fidelity cases, all reported relative standard deviations were below 1 percent. CADIS wall time was 380 minutes with serial Monaco and 18 minutes with 16-process Shift; FW-CADIS wall time was 274 and 24 minutes. These results characterize one model and computing system, not a general speedup. MAVRIC Utilities ----------------- MAVRIC-Shift-generated mesh tallies do not contain geometry and material information stored in ``*.3dmap`` files and may not suitable to perform mesh operations requiring such information. As a result, not all utilities will be compatible with MAVRIC-Shift-generated ``*.3dmap`` files, please refer to individual utility documentation. Output and review ----------------- MAVRIC-Shift writes the standard SCALE output and message files, final region and mesh tally summaries, detailed supported tally files, and supported Cartesian ``*.3dmap`` results. Shift table layout, diagnostic text, timing, and auxiliary output will differ from Monaco output. For each production calculation, verify: * normal SCALE and sequence termination and zero reported errors; * the intended data library, particle modes, histories, and process count; * source, response, tally, and importance map summaries; * tally means, standard deviations, relative uncertainties, and FOM; and * batch stability or other convergence evidence appropriate to the result. For a parity study, preserve the matched inputs, commands, output and message files, process counts, timings, and the statistical comparison. Two estimates :math:`x_1 \pm \sigma_1` and :math:`x_2 \pm \sigma_2` are consistent at a chosen multiplier :math:`k` when .. math:: \left|x_1-x_2\right| \leq k\sqrt{\sigma_1^2+\sigma_2^2}.