Helium isotope separation technology: A comprehensive review and perspective

Abstract

Helium is a light, rare gas element whose isotopes have very important applications in the fields of defense and security, energy technology, and frontier technology. Helium has two stable isotopes, helium-3 (³He) and helium-4 (⁴He), with the natural abundance of ⁴He being much higher than that of ³He. ⁴He is widely used in cryogenic refrigeration, Aerospace wind tunnel testing and Industrial leak detection, whereas ³He plays a key role in neutron detectors, deuterium-³He fusion, and cryogenic refrigeration. Currently, the only industrial source of ³He is the radioactive decay of tritium in nuclear reactors. However, the increasing demand for ³He in recent years has led to the exploration of a number of other potential avenues of obtaining it. In this paper, we summarize the various techniques for helium isotope separations to date, including cryogenic superleak, heat flush, cryogenic distillation, cryogenic adsorption, and a number of other less commonly used separations. We provide a detailed discussion and comparison of these methods. Finally, the paper summarizes and analyzes the methods used for measuring helium isotope concentrations to date.