Some peculiar features for kinetics of fission gas release from nuclear fuel on fast heating up

This paper presents studies of some anomalies observed in kinetics of fissi on products based on the model of porous fuel. A nonmonotone two-peak struc ture of a fission product flux is shown to be determined by the effect of t he system of open pores. It has been established that on heating, an explos ive growth of a flux in the region of relatively high temperatures is assoc iated with a high nonlinearity of the time dependence of phenomenological p arameters describing a fission gas release from a solid phase. The analysis has been performed, of the processes accompanying a decay of a fission pro duct solid solution. The possibility of a fuel material dispersion has been noted under the conditions of a fast reactivity accident due to a sharp ri se of the gas phase pressure in the system of closed pores. (C) 2000 Elsevi er Science Ltd. All rights reserved.