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Benchmarking a CAD-Based Monte Carlo Code Using Fusion-Specific Experiments

Tim D. Bohm, S. T. Jackson, M. E. Sawan, P. P. H. Wilson

Nuclear Technology / Volume 175 / Number 1 / July 2011 / Pages 264-270

Technical Paper / Special Issue on the 16th Biennial Topical Meeting of the Radiation Protection and Shielding Division / Radiation Transport and Protection /

Researchers at the University of Wisconsin-Madison Fusion Technology Institute and Argonne National Laboratories have recently developed a computer-aided-design-based Monte Carlo code (DAG-MCNP5) to perform nuclear analysis of complex three-dimensional systems such as ITER. In this work, DAG-MCNP5-calculated results will be compared to native MCNP5-calculated results and to measured results for ITER-specific benchmark experiments in order to provide additional quality assurance for DAG-MCNP.

Calculated results are compared for the bulk shield mock-up and the helium-cooled pebble bed (HCPB) breeder blanket mock-up, which utilize the 14-MeV Frascati Neutron Generator facility. Neutron flux was measured at different depths in these experimental mock-ups using activation foils that cover the neutron energy range of 0 to 14 MeV. Additionally, tritium production in Li2CO3 pellets was measured in the HCPB experiment.

Results of the foil activation calculations for the bulk shielding experiment and the HCPB breeder experiment show agreement within statistical uncertainty for DAG-MCNP5 and native MCNP5. Calculated results for tritium production in the HCPB mock-up also agree within statistical uncertainty for the DAG-MCNP5 and native MCNP5 calculations. Timing results showed that DAG-MCNP5 is 5.3 times slower than native MCNP5 for the bulk shield mock-up. For the HCPB mock-up, DAG-MCNP5 is 4.8 times slower than native MCNP5.

It is concluded that the close agreement of calculated foil activation and tritium production between DAG-MCNP5 and native MCNP5 in these complex and ITER-relevant geometries provides additional quality assurance for the DAG-MCNP5 code and the mcnp2cad tool used in this work.

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