Separation of multicomponent isotope mixture during filling of gas centrifuge cascade
IIsotopically modified materials with isotope content of chemical elements different from that in natural compositions, have found wide application in various fields of economy (nuclear power engineering, medicine, fundamental research, etc.). During recent decades, special attention of researchers was focused on the separation of multicomponent isotope mixtures (MCIM) in gas centrifuge (GC) cascades. Steady-state mode of MIM separation in GC cascade is preceded by non-stationary process consisting of two phases: phase 1 is the filling of GC cascade with process gas; phase 2 is the establishment of steady-state concentrations of components in the cascade. So far, research under phase 1 (filling the cascade with process gas) has not yet been implemented. Consequently, the assumption that concentrations of components in stages after filling the separation cascade correspond to their concentrations in the source MIM (feed flow of the cascade) is used for setting initial conditions for calculation and research of phase 2. Taking into consideration the effects of initial conditions on the character of the evolution of concentrations of components in the separation cascade during the subsequent non-stationary process and its duration it is expedient to research MIM separation process during filling GC cascade in order to verify the above assumption.
Results of modeling the process of filling the GC cascade with process gas for different number of separation stages and different feed flow rates, as well as for the case when feed flow is supplied to different stages of the cascade are provided in the present paper using the example of germanium isotopic separation. Regularities were identified in the evolution of concentrations of Ge isotopes in different cascade stages and flows. Separation of Ge isotopes and their distribution between the cascade stages in accordance with mass numbers take place in the process of filling the cascade. Increased feed flow results in the reduction of the duration of cascade filling, decrease of maximum concentrations of isotopes and their redistribution over the cascade stages. Concentrations of each of Ge isotopes in the cascade after its filling vary within wide range of values. It is demonstrated that the assumption of equality of concentrations of isotopes in the cascade stages after the filling to the concentrations of isotopes in the source isotope mixture (cascade feed flow) is a rude approximation. Use of this assumption for setting the initial conditions for modeling non-stationary separation cascade process results in the change of calculation dynamics of isotope concentrations in the cascade flows.
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