Benchmarking TWODANT using the French CRAC experiments

Abstract

Critical calculations of unreflected cylinders filled with fissile solution were performed using the TWODANT code with the 118-isotope, 16-group Hansen-Roach neutron cross-section library. The benchmark experiments used were the France CRAC experiments. In these experiments unreflected 300mm and 800mm cylinders were used to contain the solution. The fissile solution was highly enriched (approximately 93%) uranyl nitrate solution of various concentrations. These concentrations varied from 21.4 g/l to 383 g/l in total uranium. The calculational results were compared to the experimental results and to calculations performed using the Monte-Carlo codes MCNP with a continuous-energy neutrons cross-section library and KENO V.a with a cross-section library based on the 16-group Hansen-Roach neutron cross-section set. The TWODANT and KENO V.a codes underestimated the calculated keff for most cases whereas MCNP in most cases showed a keff estimation much closer to unity. Dimension search performed using TWODANT show that the code is able to follow the trend in the measured critical height with a relatively constant bias of 8.96% of the measured height.