Analysis of BFS-75-1 experiment

As the second stage of critical experiment plan for developing the KALIMER core design, an experimental program named BFS-75-1 was carried out, for which a uranium metal-fueled critical mock-up core was constructed at the BFS-1 facility in IPPE. In this work, the K-CORE system, being used in the KALIMER conceptual core design, has been validated against the BFS-75-1 experiment by comparing the calculated results to the measurements. The validation results show that the effective multiplication factor can be predicted within 0.2% discrepancy. The fission reaction rate distributions were calculated within 4% discrepancy in the core region, except U-238. The calculated values agreed with the measured ones within 6% for principal one and 17% for minor actinide spectral index according to various measurement methods respectively. The calculation for sodium void reactivity worth shows 24% deviation at the core boundary region. Deviations were found ranged from 1% to 7% in most of control rod experiments except the trap type control rod simulated by pellets. In the calculations of small sample reactivity worth, the first order perturbation method resulted in deviations less than 8% for U-235, U-238, Pu-239 and B-10, but much higher deviations for other materials. The calculated value for Doppler effect shows a large deviation from experiment value