Application of the Complex Equilibrium Code QUIL to Cesium-Impurity Equilibria in the Primary Coolant of High-Temperature Gas-Cooled Reactors

摘要

An equilibrium analysis has been made of the fission-product cesium in the primary coolant loop of the high-temperature gas-cooled reactor (HTGR). The species distributions that result at equilibrium have been calculated for various conditions of reactor operation. The cesium species considered were the monomer, dimer, oxides, hydroxides, and the hydride. The effect of cesium sorption isotherms on graphite also was included in the analysis.nDuring normal reactor operations, the abundant species of cesium were calculated to be elemental cesium, Cs, and the monomeric hydroxide, CsOH. Under most conditions of steam ingress, the abundant species was calculated to be CsOH.nCesium adsorbed onto graphite was stable under all steam-ingress conditions considered. Thermal transients above 1500 K were required for equilibrium transport of cesium from the core to the coolant.nThe analysis was carried out using the complex equilibrium code QUIL, designed and written with special emphasis on features that make it applicable to the fission-product problem.