The kinetics of the reactions of tellurium with stainless steel surfaces and silver aerosols

Abstract Tellurium is a very reactive fission product having great importance because of its own contribution to the health hazard if it is released to the environment and the fact that it is the precursor of decay chains involving iodine. This paper describes a new model to analyze and quantify the chemical behavior of the tellurium fission product in the primary system of pressurized water reactors under severe accident conditions. The great uncertainty on tellurium chemical behavior and the lack of specific experimental evidences suggest the need of a theoretical approach to the problem. The model quantifies the chemical interaction of tellurium vapors with silver aerosols and with the stainless steel of the pipes and structural surfaces. It is also aimed to determine the effect of oxide layers on the reaction rates. All these phenomena alter the transport through the primary system and modify the source term. Hence, the importance of an adequate description of these chemical processes. The model has been incorporated into the RAFT 1.1 transport code and has been verified and validated by using the results and boundary conditions of MARVIKEN Aerosol Transport Test 4. The results show their good agreement with the experimental data.

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