Transient Behavior of Low Enriched Uranium Silicide Miniplate Fuel under a Triplet Configuration.

Abstract

This paper describes the results of a transient experiment using low enriched (≤20wt% 235U)uranium silicide research reactor miniplate fuel. Three silicide minlplate fuel specimens assembled in a triplet configuration with a water gap of 2.38 mm were pulsed in the Nuclear Safety Research Reactor (NSRR) with an energy deposition of 78cal/g·fuel. The results obtained in this study are summarized as follows: 1. Under a restricted condition of coolant cross flow, the mid-plate in the triplet configuration (pulsed at 78cal/g·fuel) showed an extremely high peak cladding surface temperature (PCST), 475°C, which was higher than that of the other two plates (173 and 192°C). The temperature of coolant in the water gap increased rapidly to 140°C while that at the non-gap locations increased to about 50°C. Despite the poor cooling conditions, especially at the mid-plate, the three silicide miniplate fuels did not fail mechanically. Owing to the comparatively slow quenching rate from PCST and/or the small magnitude of the temperature drop during quenching, the fuels might not be subjected to the local tensile stress necessary to cause through-plate cracking.2. The bowing of the miniplate fuel caused the 2.38 mm water channel gap to be narrowed to 48% of its maximum. The uneven coolant temperature profiles in the water gaps between the miniplates might be a cause for the bowing.