Testing of a heterogeneous fuel rod in the research Impulse graphite reactor

Abstract

The paper presents the results of an experiment conducted in the IGR (Impulse Graphite Reactor) to study the behavior of a heterogeneous fuel rod under loss-of-flow conditions. A heterogeneous fuel rod is one of the options under consideration for the layout of a core of fast reactors. The fuel rod consists of two zones of enriched fuel, separated by a fuel zone with low content of uranium-235.During the experiment, conditions were provided that correspond to the expected operating conditions of a fuel rod in a fast reactor at a nominal power, including the level and distribution of energy release throughout the height of a fuel rod and the temperature of an ambient sodium.The experiment results allowed evaluating the state of fuel pellets subjected to thermal impact, typical for the initial phase of an Unprotected Loss-of-Flow (ULOF), in which there is a decrease in heat removal from fuel rods, heating of fuel pellets up to the melting temperature and destruction of the fuel cladding.The methodological approaches and obtained experimental data will be used in preparation and conduction of experiments with model heterogeneous fuel assembly (FA) when simulating the ULOF.