Dr. X. Steve Xiao

Savannah River National Laboratory (SRNL)

Hydrogen isotope separation development at SRNL

Abstract: 

Engineering

TCAP (Thermal Cycling Absorption Process) is the most advanced hydrogen isotope separation process based on palladium hydride technology. SRNL is the technology leader in the world supporting tritium production for the U.S. nuclear weapons stockpile. Palladium and other materials were found to have very large hydrogen isotopic effects shortly after the discovery of deuterium in 1931 and tritium in 1934. Batch palladium chromatography for hydrogen isotope separation dates to the 1950’s. A “continuous” process using Pd chromatographic separation did not appear until half a century later with successful development of the TCAP in SRNL. The TCAP invention is an engineering achievement with simple design and advanced control logic and is suitable for radioactive confinement.

Theoretical

University of Manchester reported a 10:1 H/D isotopic selectivity across graphene and two other types of 2-D crystals, theorizing a 30:1 H/T selectivity by zero-point energy. However, the measured isotope effect independent of the types of 2-D membrane remained puzzling. The fact that the selectivity depends on isotope mass but not the type of membrane or membrane thickness triggered SRNL to consider quantum tunneling mechanism. A quantum tunneling solution was derived from 1-dimentional Schrödinger equation that explained Manchester data, and further predicted 58.5:1 H/T selectivity. Investigation is ongoing to verify H/T selectivity in order to conclude between the two hypotheses.

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