Burnup Performance of modified CANDLE shuffling in axial direction on gas cooled fast reactors with UN-Th fuels

The modified CANDLE (Constant Axial shape of Neutron flux, nuclide densities, and power shape During Life of Energy production) strategy shuffling in an axial direction has been successfully applied to gas cooled fast reactor. This paper investigated the utilization of natural uranium, enriched nitride and Thorium ( 238 U 15 N and 232 Th) as fuel on 3000MWt reactor power and refuelling every 10 years of burnup. The reactor core is partitioned into ten regions with the same volume in the axial direction. Initially, a fuel input ( 238 U 15 N and 232 Th) is placed in region 1. After ten years of burnup, a fuel in region 1 was moved to region 2, then to region 3, and so on until the fuel in region 9 was moved to region 10. The fuel in 10 th region was removed in the core. The neutronic computations were performed in two different ways by using SRAC 2006 code and JENDL4.0 as a nuclear data library. Firstly, PIJ was used for fuel cell calculations and secondly CITATION for a reactor core calculation. The results show that the effective multiplication factor is greater than one, at the beginning of life, its value is approximately 1.0028 and at the end of life is approximately 1.0279. This indicates that the reactor is capable to operate through a burn-up period by employing 238 U 15 N and 232 Th (10%) as fuel cycle input. At the beginning of life, the integral conversion ratio is approximately 9.9455 and at the end of life is approximately 1.2906. The burnup level at the end life is about 30.29% HM.