Investigation on fuel pebble parameter in the calculation of RGTT200K thorium core

In RGTT200K design, the utilization of thorium as a promising fuel becomes an alternative that should be considered. This paper discusses fuel pebble parameter in the thorium core calculation for RGTT200K. The calculations were performed with Monte Carlo transport code MCNPX and continuous energy cross section data library ENDF/B-VII at the temperature of 1200K. The ²³³U enrichment between 4% and 20% also the increased ²³²Th/²³³U fuel loading from 0.1 g to 15 g per pebble were varied to analyze the trends of criticality and burnup behavior of RGTT200K thorium core. The calculation results show that low fuel loading causes RGTT200K core has over moderated condition. The addition of fuel loading after reaching its maximum condition causes k_eff curve decreases and RGTT200K thorium core has undermoderated condition. The core with low fuel loading indicates high decrease in ²³³U and high increase of ²³³Pa concentration. Instead of the core with high fuel loading indicates low decrease in ²³³U and low increase of ²³³Pa concentration. The fuel loading of 6 g with ²³³U enrichment of 8% can be considered in design of RGTT200K with a specific criticality and burnup values. (author)