Development of a kinetics code, AGNES, for the evaluation of criticality accidents in solution fuel systems

A kinetics code, AGNES (Accidentally Generated Nuclear Excursion Simulation code) is developed for the evaluation of criticality accidents in solution fuel systems. Nuclear excursions in solution fuel systems is affected by the behaviour of 'radiolytic gas' void. This void causes power oscillations by changing the solution fuel density and a pressure pulse by its sudden appearance in the solution. In an evaluation work of the consequence of a criticality accident, these void effects must be considered carefully. The AGNES code can calculate the void-effects with two void models. The production, the growth and the movement of voids and their effects on the reactivity can be calculated with the 'Modified energy model'. Using this model, the power oscillations can be simulated. The pressure pulse at a first power excursion as well as the void volume at that time can be calculated with the 'Pressure model'. Some calculations performed for 'CRAC' experiments show good agreements with the experiments. (author)