Obtaining the Optimum Transuranic Layer Configuration for Transmutation in Molten Salt Reactor Fuel Channel

Incineration of transuranic (TRU) elements can be performed in various types of nuclear reactor. Thermal molten salt reactor (MSR) can be utilised for TRU incineration, typically by blending TRU elements with the carrier salt. This method has issues in low trifluoride solubility and lower TRU burnup than fast spectrum MSR. This study proposes an innovative method of TRU incineration in MSR as a heterogeneous configuration by inserting tubular TRU layer into MSR fuel channel. To obtain optimum configuration, TRU layers comprised of reactor grade plutonium (RGPu) and minor actinide (MA) were inserted in an MSR fuel channel in central, middle, and outer configurations. Neutronic analysis was performed in the MSR fuel channel using MCNP6.2 code, and decay analysis was done using ORIGEN2.1. The analysed parameters include infinite multiplication factor, temperature coefficient of reactivity (TCR), transmutation efficiency (TE), and post-irradiation decay activity. It was observed that TRU layer with a volume fraction of 5% in a narrow fuel channel and outer configuration exhibit the optimum TE and improved the TCR. After 1460 days of irradiation, the TE was found to be 30.98% and lower radioactivity than unirradiated TRU after 400 years of decay. This result is promising as an initial stage prior to whole core calculation.