Nuclear criticality safety evaluation of the ℗33U inventory at the Oak Ridge National Laboratory using ENDF/B-V cross section

This work presents a nuclear criticality safety evaluation of the ²³³U inventory which is stored in two different facilities at the Oak Ridge National Laboratory (ORNL). The evaluation employs KENO V.a with ENDF/B-V cross sections. The inventory is housed in retrievable storage wells within Building 3019 and three fuel drain tanks within the Molten Salt Reactor (MSR) Fuel Drain Tank Cell (FDTC) at ORNL. In order to establish subcritical storage limits on the basis of calculations, the calculational method (e.g., Monte Carlo) and ENDF/B-V cross section data were validated against ²³³U critical experiments. Once validated, KENO V.a was used to evaluate the storage wells located in Building 3019. The calculated k_eff for the nominal configuration of the wells is 0.8438 ±0.0018 which is sufficiently subcritical. Moreover, the calculated storage well loading limits for ²³³U are 2.45, 1.90, 1.75, 1.30 and 0.95 kg U/ft for H/U atom ratios of 0, 3, 5, 10 and 20, respectively. After examining the storage wells, the FDTC was evaluated using KENO V.a, and the calculated kerr of the nominal configuration of the three drain tanks is 0.8432 ± 0.0028 which is sufficiently subcritical. The FDTC was also evaluated for credible upset conditions using KENO V.a. The results of this evaluation indicate that the facility is sufficiently subcritical during the upset conditions.