The cost reduction of electrolytically produced heavy water and hydrogen in the context of some new process parameters

Abstract

Hydrogen is an extremely important material, which is commonly used in many industrial processes in huge quantities, while its heavy isotopes, deuterium (D) as heavy water, and tritium (T) have great significance for nuclear energetics. Thus, improvements in their production are always of interest. Electrolysis (sometimes in combination with other methods) is often used for heavy water production or re-enrichment. It is a high energy consuming method at the same time with high isotope separation factors. An efficient way to achieve both, energy savings and a significant increase of the HID separation factors simultaneously, is applying water electrolysis from alkaline solutions, using catalytic cathode materials made from hypo-hyper-d-electronic combinations of transition metals and electrode in situ activation with tris-(ethylenediamine)-Co(III)-chloride complex. The appropriate conditions were investigated in this study. The dependence of isotope enrichment on the amount of water that must be electrolyzed was calculated using the Rayleigh equation. From that dependence the amounts for obtaining pure heavy water, i.e the corresponding energy savings, were estimated for different values of the separation factor, along with the minimum number of electrolytic stages in an enriching cascade. The method is discussed in a context that assumes heavy water as a by-product of hydrogen/oxygen generation, being an energy storage medium in a certain electroenergetic system during periods of the day when the consumption of energy from the system is reduced. This could be of importance for countries with a high percent of nuclear energy in the system, to avoid plant power reduction. If the discussed conditions are applied, hydrogen/oxygen can be produced at a reduced cost, delivering a D-enriched electrolyte to the subsequent heavy water production cascade.