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SCALE Criticality Safety and Radiation Shielding

This course provides instruction on the use of the CSAS6 sequence for criticality safety calculations and the MAVRIC shielding sequence with 3-D automated variance reduction for deep-penetration problems. CSAS6 uses either the KENO-VI or Shift 3-D Monte Carlo (MC) code to solve the k-effective eigenvalue problem for criticality safety. MAVRIC uses either the Monaco or Shift 3-D MC code for fixed-source shielding analysis. Both sequences use the SCALE Standard Composition Library and the SCALE Generalized Geometry Package (SGGP), which allows for versatile modeling of complex geometries and provides convenient, efficient methods for modeling repeated and nested geometry configurations such as lattices.

The MAVRIC sequence is based on the CADIS (Consistent Adjoint Driven Importance Sampling) methodology. For a given tally to be optimized in a MC calculation, the CADIS method uses the result of an adjoint calculation from the Denovo 3-D deterministic code to create both an importance map for weight windows and a biased source distribution. MAVRIC is completely automated in that from a single user input, it creates the cross sections (forward and adjoint), computes the adjoint fluxes, creates the importance map and biased source, and then executes MC calculation. An extension to the CADIS method using both forward and adjoint discrete ordinates calculations (FW-CADIS) is included in MAVRIC so that multiple point tallies or mesh tallies over large areas can be optimized (calculated with approximately the same relative uncertainty).

Both CSAS6 and MAVRIC use ENDF/B-VII.1 or ENDF/B-VIII.0 nuclear data distributed with SCALE to perform continuous energy (CE) or multigroup (MG) calculations. Both sequences can also be used with the Fulcrum consolidated SCALE user interface for interactive model setup, computation, output review, and 3-D visualization. Instruction is also provided on the SCALE material input and resonance self-shielding capabilities and the data visualization capabilities within Fulcrum for visualizing fluxes, reaction rates, and nuclear data as well as mesh tallies. CSAS6 and MAVRIC/Monaco can be applied together to perform an integrated criticality accident alarm system (CAAS) analysis.

No prior knowledge of SCALE is required.