Publications Details

Interaction of tin telluride and cesium hydroxide with reactor materials in steam

Elrick, R.M.; Ouellette, A.L.

Two laboratory tests were designed to study the behavior of SnTe and CsOH in steam at {approximately}1230 K with the reactor materials Inconel 600, 304 stainless steel, silver and nickel, a nonoxidizing constituent of Inconels and steels in reactor accident environments. Thermochemical calculations examined the sensitivity of species in the H-O-Cs-Te-Sn system to temperature, to hydrogen and SnTe concentrations and to total system pressure. Test results indicate that should SnTe be formed from fission product tellurium and the tin in zircaloy cladding, it may not remain stable in steam in the presence of unoxidized (or lightly oxidized) metals. Calculations show a small amount of SnTe, in equilibrium with steam, decomposes to primarily Te and SnO. It is felt that these decomposition producets react with the reactor materials since Sn and Te are seen to be deposited separately and not as SnTe. The deposition velocity for SnO vapor in the system was estimated to be 0.57 m/s. The response of CsOH in the system was similar to behavior observed previously: some cesium combined with silicon found in Inconel and stainless steel oxides. At lower temperatures ({le}940 K) CsOH corroded Inconel, stainless steel and nickel providing enhanced surface area for additional trapping of species. There was no experimental evidence for the formation of cesium telluride; vapor equilibrium calculations did not predict formation either. 33 refs., 29 figs, 7 tabs.