Downstream behavior of volatile iodine, cesium, and tellurium fission products: Final report

The downstream behavior of fission product iodine, cesium, and tellurium has been investigated by injecting mixtures of CsI, CsOH, and Te into a superheated steam/hydrogen stream and determining the physical and chemical changes that took place as the gaseous mixture flowed down a 3.65-m (12-ft) long reaction duct on which a temperature gradient (1000/degree/--200/degree/C) had been imposed. Deposition on the wall was found to occur by either reaction with the surface, vapor condensation, or aerosol collection. The deposition processes were influenced by reactions in the gas stream between CsI and CsOH and between Te and CsOH. Revaporization behavior was studied by flowing steam down the duct after deposition and determining the changes in the deposition and determining the changes in the deposition pattern on the wall of the duct. The deposits were characterized by chemical, SEM, and x-ray diffraction analyses. The experimental data were used in modeling the downstream behavior of iodine, cesium, and tellurium in a superheated steam/hydrogen stream. 20 refs., 18 figs., 30 tabs