Nuclear excursions in aqueous solutions of fissile materials

Fissile materials in the form of aqueous homogeneous solutions are used during the chemical processing of nuclear materials. In this form there exists the possibility of an accidental criticality. A one-dimensional multi-region model was developed for simulating fast power excursions in a cylinderical homogeneous aqueous fissile solution. The model includes a novel method for computing reactivity feedback that accounts for the axial distribution of power and solution density. The feedback method is based on the change in neutron leakage due to a change in solution density. The model also includes an equation of state derived from quasi-static thermodynamic theory for a solution containing gas bubbles. The model was compared to the KEWB-5 (Kinetic Experiments on Water Boilers) series of experiments. The model could approximate the values of peak power and pressure found in the experiments, but the pressure curves did not match the shapes of the experimental pressure traces