In October 2010, DOE/NNSA worked with Belarus to remove 88 kilograms of Russian-origin HEU fresh and spent fuel. As a compensation for removed fresh HEU fuel Belarus was supplied equivalent amount of unique UZrCN low enriched uranium (LEU) fuel. This fuel was loaded in HYACINTH critical assembly to conduct different types of nuclear research in collaboration with the US DOE national laboratories. Transient physics studies were performed using HYACINTH critical facility with UZrCN fuel. In these studies, experiments and analyses were carried out for the movement of the water moderator or the control rod inside the HYACINTH critical facility. The change of the neutron flux and the neutron multiplication during the transient events were determined. In these HYACINTH configurations, the fuel material is low enriched uranium zirconium carbon nitride (U<sub>0.9</sub>-Zr<sub>0.1</sub>-C<sub>0.5</sub>-N<sub>0.5</sub>) with ~12.5 g/cm3 density and ~11.3 g/cm3 uranium density. Water is the moderator and the reflector material, and the fuel clad material is a steel alloy. The fuel rods arrangement has a triangular lattice. The absorber material is born carbide with fuel rod follower or Plexiglas rod to avoid any disturbance for the neutron flux field. In the first transient experimental set, the water moderator level of the HYACINTH critical configurations was changed with different speed. In the second set, the absorber material was inserted with different speed inside the HYACINTH critical configurations. The neutron flux was measured in all the experiments as a function of the time. MCNP and SERPENT Analytical simulations were performed to calculate the neutron flux and the reactivity during these transients. The MCNP neutron tracking process was updated to simulate the geometrical model changes during the transient. In this paper, the experimental and the analytical results are presented and compared successfully to prove the capability of using UZrCN LEU fuel in critical assemblies.<i></i>
Year
2020
Abstract