A semi-empirical model of radiolytic gas bubble formation and evolution during criticality excursions in uranyl nitrate solutions for nuclear criticality safety assessment

A novel mathematical and computational model for the formation and evolution of radiolytic gas in aqueous fissile solutions is presented. The model predicts the rate at which bubbles are formed and/or removed from the system using semi-empirical correlations calibrated by means of numerical simulation. The model is able to reliably predict the behaviour of aqueous fissile solutions, including transient effects due to the formation and removal of radiolytic gas. A further extension to the model enables its application to boiling systems.