Hydrogen Isotope Separation by Plasma-Chemical Method

Abstract

Deuterium transfer (exchange) reaction as shown in HDO+H 2 =H 2 O+HD was studied as a case similar to the tritium transfer reaction as shown in DTO+D 2 =D 2 O+DT, the first step in tritium isotope separation of the tritiated heavy water DTO. The transfer reaction was plasma-chemically catalyzed by allowing a gas mixture such as H 2 O/D 2 , D 2 O/H 2 , H 2 O/HDO/H 2 or H 2 O/D 2 O/HDO/H 2 to flow through an atmospheric pressure discharge zone formed in a reaction chamber, the inner temperature of which was maintained just above 100 C. The plasma-chemical reactions diagnosed by infrared and emission spectroscopy revealed that the mixture underwent instantaneous deuterium transfer reactions as it passed the zone. The effectiveness of the method was demonstrated by high deuterium transfer rate, high separation factor of the transfer and a possibility of miniaturizing the separation facility.

Hollow-Cathode Based Electrical Discharge in Atmospheric Pressure Water Vapor at Wide Range of Temperature

“…The ready recombination of H 3 O þ species will make it hard to sustain the discharge through atmospheric pressure water vapor. However, our previous study 1) revealed that AC powered MHC discharge in atmospheric pressure water/ hydrogen gas mixture was stabilized although it showed oscillatory current profile. Thus, we adopted MHC configuration as the electrode geometry to induce the discharge in pure water vapor at atmospheric pressure.…”

“…The details of the experiments, particularly the geometric configurations of the electrode and the spectroscopic setup, are described elsewhere. 1,12) The micro-hollow electrodes assembly for generating atmospheric pressure water plasma is shown in Fig. 1(a).…”

“…Water molecules excited in atmospheric pressure electrical discharge (APD) can have high reactivity in some chemical reactions, which may be explained in terms of plasma catalytic effects manifested by the nonthermal plasma. For examples, hydrogen isotope exchange reaction between tritiated water and hydrogen gas can be catalyzed in electrical discharge, 1) providing an effective means for tritium separation. The high reactivity is attributed to free radicals and the molecules, in their excited vibrational or electronic states, which were formed during their interaction with energetic electrons in the discharge region.…”

Deuterium Recovery from H-D Gas Mixture by Thermal Diffusion in the Device of Branch Columns for Improved Performance

“…A number of methods for the separation of hydrogen isotopes, such as by means of palladium membranes (1)(2)(3)(4)(5), gas chromatography (6)(7)(8)(9), pressure swing adsorption (10,11) and plasma-chemical reaction (12), have been reported. Among them, the first method is potentially competitive with other methods for small and intermediate scale applications (13).…”