# Presentation: 817233

## 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**

## 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**

## 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**

## 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**

## 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 **

## 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**

## 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**

## 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**

## Monaco Example:  Ueki Experiment

## Monaco Example:  Ueki Experiment

## Monaco Example:  Ueki Experiment

## 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**

## 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**

## CADIS Methodology

**Want to find:**

**typical problem:**

**Or some detector response related to flux:**

- flux

## 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. **

## 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:**

## CADIS Methodology

**Weight window target weight values:**

**Weight window size:  (c=upper/lower)**

## 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**

## 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**

## MAVRIC Example – Weight targets

## MAVRIC Example - Source Biasing

## MAVRIC Example Results

## MAVRIC Cask Example

## MAVRIC Cask Example

## MAVRIC Cask Example

## MAVRIC Cask Example

**Speed up:  583**

## MAVRIC Cask Array Example

## MAVRIC Cask Array Example

## MAVRIC Cask Array Example

**Speed up:  28**

## MAVRIC Cask Array Example

##          GeeWiz

## 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

## 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**

## 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