Separation of neon-21 from natural neon by thermal diffusion

The rare stable isotope neon-21 comprises 0.27 percent of natural atmospheric neon. In earlier work, separation of neon-21 in high purity was accomplished by thermal diffusion with the aid of deuterated methane as an auxiliary gas. The separation is now being accomplished by thermal diffusion without the use of an auxiliary gas. In the latter process a two-stage, multiple column, thermal diffusion system is employed. The most abundant isotope, neon-20, is removed in the first stage, leaving a binary mixture of neon-21 and neon-22. The binary mixture is further separated in the second stage of the process, yielding high purity neon-21. It was found that the performance of the separation apparatus in both the transient and steady-state modes could be accurately predicted from thermal diffusion column and cascade theory. The thermal diffusion separation technique can be used for the separation of a wide variety of gas mixtures, including isotopic separations of stable and radioactive nuclides. Recent examples include separation of argon-37 and argon-39 from atmospheric argon and the enrichment of krypton-85 and xenon-136 from nuclear reactor fission gas