Interaction of tritium and helium with lead–lithium eutectic under reactor irradiation

Abstract

This paper describes the study of tritium and helium generation and release from the lead–lithium eutectic under irradiation in the IVG1.M reactor (Institute of Atomic Energy of the Republic of Kazakhstan).The experiments were carried out using the method of mass-spectrometric registration of released gases.Experimental conditions were as follows: the irradiation temperature was from 573K to 773K; the reactor power levels were 1, 2 and 6MW.The study allowed to obtain the temperature dependences of tritium and helium release from the lead–lithium eutectic at different reactor powers (for different neutron fluxes and, respectively, for different rates of helium and tritium generation in material). Phenomenological models were proposed for description of the processes of tritium and helium generation and release from the lead–lithium eutectic. These models allowed us to describe the experimental data very well. Helium release simulation assumed that the flow of helium from the eutectic's surface is linearly dependent on its bulk concentration. For modeling the tritium release the process was divided into two phases: the first one—the yield of tritium atoms on the surface, has been described in the same assumption as for the helium release; and the second phase included a description of the second-order desorption from the surface of the eutectic.All the main parameters of the models, such as the effective release coefficient of tritium and helium atoms on a surface, the effective constant of desorption rate of tritium atoms from the eutectic surface were identified.