Benchmark Critical Experiments of a Heterogeneous System of Uranium Fuel Rods and Uranium Solution Poisoned with Gadolinium, and Application of Their Results to JACS Validation

Abstract

A series of critical experiments were performed using heterogeneous cores at the Static Experiment Critical Facility (STACY) of the Japan Atomic Energy Agency (JAEA) in order to obtain systematic benchmark criticality data concerning the dissolving process in reprocessing plants. Focusing on the use of gadolinium as a soluble poison, critical mass was measured for a combination of uranium dioxide fuel rods (5 wt% 235 U) and uranyl nitrate solution (6 wt% 235 U) poisoned with gadolinium (Gd). Fuel rods were arrayed with a 1.5 cm lattice interval in the poisoned fuel solution in a 60-cm-diameter cylindrical tank. The uranium concentration of the solution was roughly kept at about 330 gU/L, and the Gd concentrations were varied up to 0.1 gGd/L. The other series of experiments were also conducted, as reference cases, varying uranium concentration in the fuel solution without Gd. The results provided benchmark criticality data for validation of neutron multiplication factor calculation on heterogeneous systems such as a dissolver. Validation calculation of JACS based on the newly obtained benchmarks supports the justification of its utilization for the criticality safety analysis.

Synthesis and Characterization of Cellulose Acetate Membranes with Self-Indicating Properties by Changing the Membrane Surface Color for Separation of Gd(III)

“…The present study was conducted for Gd(III) separation from aqueous solutions. Gadolinium nitrate is one of the most used moderators for nuclear reactions which, in the recent year, successfully replaced boron for this type of application [7,[33][34][35]. The basic idea of the current research was to have an easy method to remove gadolinium from aqueous solutions and also the possibility that the membrane would indicate the gadolinium separation without adjacent analysis.…”

Crown Ether-Immobilized Cellulose Acetate Membranes for the Retention of Gd (III)

“…The present study was performed to separate Gd (III) from water, using cellulose acetate membranes with immobilized crown ethers. Gadolinium nitrate is used to control nuclear reactions, which, in the last years, has successfully replaced boric anhydride for this [18,[35][36][37]. Given that nuclear solutions are of high purity, the possibility of having and separating other interferences from the system was eliminated from the beginning [18,38].…”