Modeling and simulation of transient performance of uranium enrichment cascade in the event of a crash of gas centrifuge machines

Abstract

One of the significant phenomena in the operational conditions of the enrichment cascades is the sudden crash of a number of separate machines along the cascade. In order to investigate the effect of gas centrifuge crash on cascade performance, separation of the cascade in a transient condition should be modeled. In this paper, the performance of two-component symmetric enrichment cascades was modeled, using partial mass balance equations in the transient condition. Nonlinear equations of the model were also discriminated against using Crank Nicholson's finite difference method and the q iteration method was used to solve the equations. The results of the computer simulation of the model cascade for the enrichment of uranium 235 showed that if the crash of gas centrifuge machines occurs at the end of the enrichment part of the cascade, the product concentration will decrease more and more, and it takes a longer time to reach new steady-state condition. For the cascade and the conditions used in this paper, with the crash of a machine, the greatest reduction in product concentration compared to the pre-incident state is, 0.5% percent and the highest increase in waste stream concentration compared to the pre-incident state is 0.2 percent. It was also observed that the cascade performance of machines with a higher separation factor is less affected by the crash of machines. The results showed that the gas hold up has a small effect on the variation of the 235 isotope concentration in the product stream and only affects the time to reach equilibrium in the cascade.

Keywords

• symmetric cascade
• two-component enrichment
• transient simulation
• gas centrifuge crash
• separation factor