Post-Test Analysis of the 28 Element High Temperature Thermal-Chemical Experiment CS28-l

Abstract

An out-of-pile 28-element fuel channel experiment has been performed to improve the understanding of fuel channel behaviour under severe accident conditions and to provide validation and assessment data for various high-temperature thermal-chemical codes. Controlled input parameters for the experiment were superheated steam inlet temperatures and flow rates, moderator water temperatures, and fuel element simulator bundle power. Measured variables included test-section temperatures and pressures, steam outlet temperatures, and hydrogen production from the exothermic zirconium/steam reaction. The experiment was successful in obtaining fuel element simulator temperatures as high as 1730°C, with a peak hydrogen production rate of 0.28 mol/s recorded during the experiment. This paper summarizes the experimental results and describes a post-test analysis for this experiment using the fuel-channel code CHAN-11-WL (MOD-28a) to help interpret the experimental data and to enhance our understanding of the physical phenomena involved. The code calculated fuel element simulator temperatures using the empirical oxidation correlations of Urbanic-Heidrick and Leistikow-Prater-Courtright. Analysis of the results indicated the zirconium/steam reaction at various test-section locations was self-sustaining as both measured and simulated temperatures continued to increase beyond 1680°C after electric power to the test section was turned off. The experiment provided a valuable database for assessing various high-temperature thermal-chemical models used to assess fuel channel safety in a CANDU** pressurized heavy-water reactor. The work reported in this paper was funded by the CANDU Owners Group (COG).