Shutdown dose rate benchmarking using modern particle transport codes

Shutdown dose rate benchmarking using modern particle transport codes

Shutdown dose rate benchmarking using modern particle transport codes 150 150 UKAEA Opendata
UKAEA-CCFE-PR(19)76

Shutdown dose rate benchmarking using modern particle transport codes

Shutdown dose rate calculations provide an essential input to the design and research of fusion power plant technology. They allow the estimation of dose to personnel and equipment during planned and unplanned maintenance. The mesh coupled rigorous 2 step (MCR2S) methodology used at Culham Centre for Fusion Energy (CCFE) was originally developed to link the MCNP particle transport code and the FISPACT-II inventory code. As new particle transport codes are developed there is a strong motivation to move towards a code agnostic approach allowing us to take advantage of the modern codes’ features. This paper details the current MCR2S work-flow and looks at the developments made with incorporating two other transport codes, Serpent 2 and OpenMC, into the methodology. Two benchmarks, the FNG shutdown dose rate experimental benchmark and the ITER computational benchmark, have been performed for both codes and compared to results produced with MCNP. In general, the results show that MCNP, Serpent 2 and OpenMC give shutdown dose rate results similar to the FNG experiment. For both FNG experimental campaigns it was shown that all of the codes predicted the dose in the central cavity of the model to be comparable to the measured result. However, all codes appeared to slightly overestimate the dose rates for Campaign 1 (all results had a C/E between 1 and 1.5) and underestimate the dose rates for Campaign 2 (all results had a C/E between 0.6 and 1). Some differences were seen between OpenMC and MCNP for the ITER port plug benchmark, where the lack of variance reduction in OpenMC meant that the neutron flux estimates at the rear of the model were not well converged. This led to differences of up to 13% in the shutdown dose rate tallies. It was shown that Serpent 2 and MCNP, where variance reduction was used, gave very similar shutdown dose rate results. These were within 3% of each other for all tallies. Although some areas for development of the Serpent 2 and OpenMC transport codes have been highlighted, overall the comparisons give confidence that the implementation of these two transport codes into the MCR2S work-flow has been carried out successfully.

Collection:
Journals
Journal:
Nuclear Fusion
Publisher:
IOP (Institute of Physics)
Published date:
20/04/2020