Monaco/MAVRIC: Computational Resources for Radiation Protection and Shielding in SCALE Douglas E. Peplow, Stephen M. Bowman, James E. Horwedel, and John C. Wagner Nuclear Science and Technology Division Oak Ridge National Laboratory Computational Resources for Radiation Protection and Shielding - II American Nuclear Society Winter Meeting November 16, 2006 Albuquerque, New Mexico

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 2 Introduction  Monaco — multi-group Monte Carlo code  MORSE physics  SCALE Generalized Geometry Package (same as KenoVI)  MAVRIC — Automated Variance Reduction  CADIS Methodology  GTRUNCL3D and TORT  Monaco for Monte Carlo Calculation  GeeWiz — the Windows GUI for using many SCALE programs  Monaco/MAVRIC will be part of SCALE 6

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 3 SCALE  Standardized Computer Analyses for Licensing Evaluation  Collection of codes for performing  criticality safety  radiation shielding  spent fuel characterization  reactor physcis  radiation source terms and decay heat

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 4 SCALE  Functional modules – physics calculations  KENO, Monaco, ORIGEN-S, NEWT, XSDRNPM  Control modules automate the execution and data exchange of individual codes to perform various types of analyses in calculation sequences  CSAS, MAVRIC, TSUNAMI, TRITON  Multi-group and continuous energy cross- section data

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 5 Current SCALE Shielding Modules  SAS1 – 1-D discrete ordinates Shielding Analysis Sequence  automates cross-section processing, transport calculation, and calculation of dose rates outside a defined shield  Combined 1-D criticality/shielding analysis (e.g. CAAS)  SAS4 – 3-D Monte Carlo Sheilding Analysis Sequence designed for calculation of radiation doses exterior to a transport/storage cask. Uses XSDRNPM to calculate adjoint fluxes for the generation of biasing parameters  MORSE  3-D Monte Carlo functional module used in SAS4  Different geometry package than the SCALE Monte Carlo criticality (KENO) codes  Legacy code, geometry package has not been updated in >20 years

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 6 Current SCALE Monte Carlo Shielding  SAS4 – Shielding Analysis Sequence  Automated 1-D axial or radial variance reduction  Not updated in more than a decade  Design limitations based on cylindrical cask geometry  Effective for cask mid-plane and top center doses  Not well suited to cask corners or very heterogeneous geometries  Not effective for general purpose shielding analyses  Hence, need for modern Monte Carlo tool with automated 3-D variance reduction (AVR) for general shielding applications

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 7 Monaco  3-D Multi-group Monte Carlo  MORSE physics  SCALE Generalized Geometry Package (same as KenoVI)  Fixed source  Variety of geometric shapes  Can use a mesh-based source  Tallies  Point detectors, region tallies, mesh tally  Convolves fluxes with detector responses

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 8 Monaco  Variance Reduction  Biased source energy distribution  Source direction distribution  Path length stretching  Point detector tallies  Weight windows by region and energy group  Advanced Variance Reduction  Mesh/energy group based importance map  Mesh/energy group based biased source

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 9 Monaco Example: Ueki Experiment

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 10 Monaco Example: Ueki Experiment

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 11 Monaco Example: Ueki Experiment

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 12 MAVRIC 3-D Automated Variance Reduction  SCALE cross section processing  GTRUNCL3D and TORT  Computes the adjoint flux for a given response  Monaco for Monte Carlo calculation  Importance map (weight windows for splitting and roulette)  Biased source distribution

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 13 CADIS Methodology  From the adjoint flux  Importance map for MC transport (weight windows for splitting and roulette)  Biased source distribution  Biased source and importance map work together (i.e., are consistent)  A. Haghighat and J. C. Wagner, “Monte Carlo Variance Reduction with Deterministic Importance Functions,” Progress in Nuclear Energy, 42(1), 25-53, (2003). Consistent Adjoint Driven Importance Sampling

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 14 CADIS Methodology  Want to find:  typical problem:  Or some detector response related to flux: flux

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 15 CADIS Methodology  If the adjoint flux for a given detector response is known:  Then the detector response is simply:  Unfortunately, the exact adjoint flux may be just as difficult to determine as the forward flux.

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 16 CADIS Methodology  With an approximate adjoint flux for a given detector response:  Total detector response is approximated as:  Biased source distribution found to be:  Sampled particles start with weights of:

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 17 CADIS Methodology  Weight window target weight values:  Weight window size: (c=upper/lower)

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 18 SCALE Sequence: MAVRIC  Cross sections  Multi-group SCALE libraries  Create adjoint and forward cross section sets  Find the approximate adjoint flux  GRTUNCL3-D – first collision code (for pnt det)  TORT – 3-D discreet ordinates transport code  Forward Monte Carlo - Monaco  Uses mesh-based biased source  Uses mesh-based importance map (weight windows)  Automate as much as possible An implementation of the CADIS Methodology

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 19 SCALE Sequence: MAVRIC Monaco with Automated Variance Reduction using Importance Calculations SCALE Driver and MAVRIC Input ICE Monaco End Optional: TORT adjoint cross sections Optional: 3-D discrete ordinates calculation 3-D Monte Carlo Resonance cross-section processing BONAMI / NITAWL or BONAMI / CENTRM / PMC TORT GRTUNCL-3D Optional: first-collision source calculation

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 20 MAVRIC Example – Weight targets

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 21 MAVRIC Example - Source Biasing

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 22 MAVRIC Example Results

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 23 MAVRIC Cask Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 24 MAVRIC Cask Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 25 MAVRIC Cask Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 26 MAVRIC Cask Example Speed up: 583

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 27 MAVRIC Cask Array Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 28 MAVRIC Cask Array Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 29 MAVRIC Cask Array Example Speed up: 28

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 30 MAVRIC Cask Array Example

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 31 GeeWiz

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 32 KENO3D  Powerful 3-D interactive visualization tool that displays KENO V.a or KENO-VI geometry models  Plot calculated results (e.g., fluxes and reaction rates) over geometry

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 33 KENO3D  help  top view, side view  toggle wireframe  toggle highlight edges  orbit  rotate  pan  zoom options  axis  legend  simple cuts  rebuild in window  dockable toolbars

O AK R IDGE N ATIONAL L ABORATORY U. S. D EPARTMENT OF E NERGY 34 Future Work  MAVRIC Sequence  Automatic homogenization in importance map  Refine standard set of TORT parameters  Incorporate new Monaco tallies  Optimizing mesh tallies  Monaco  Modern F95 programming structures  Modern, block/keyword input structure  Output to separate (html) tables  Larger variety of source descriptions  Larger variety of tally options – multipliers, totals  Cross-Section Data  ENDF/B-VI coupled multigroup library  Testing, Testing, then a bit more Testing

Discussion & Questions