Calibration of tritium enrichment factor in solid-polymer electrolyte device based on correlation between deuterium and tritium

Abstract

BackgroundSolid-polymer electrolyte (SPE) water electrolysis has been widely used to concentrate low-level environmental tritium for measurements. It has the advantages of electrolyte elimination, infinite reduction ratio, high current, safety, and environmental friendliness. However, the use of high-activity tritium samples for the calibration of its tritium enrichment factor Et causes a tritium memory effect in the system.PurposeThis study aims to reduce the tritium contamination caused by high-activity tritium samples during calibration.MethodsFirst, the deuterium method (DM) was used to calibrate the prepared SPE-based tritium enrichment system. The strong correlation between the tritium-to-protium (β) and deuterium-to-protium separation factors (α) during the electrolysis was determined to obtain the electrolytic cell constant, k = αβ-1/βα-1. Then, based on the deuterium enrichment factor Ed, the tritium enrichment factor (Ed)k of the SPE-based tritium enrichment system was determined. Finally, the influence factors of the k-value were analyzed, and the tritium enrichment factors derived via low-level tritium measurements using the DM and spike-proxy method (SPM) were compared.ResultsThe value of k is approximately 1.088 9, with a slight variation of 0.89% among cells. The k-value depends on the electrode material, but it is almost independent of the initial volume of water.ConclusionsThe k-value can be used as a constant for calibration of the tritium enrichment factor for the same types of electrolyzer with high accuracy and precision.

Keywords

• solid-polymer electrolyte water electrolysis
• separation factor
• tritium
• deuterium
• tritium enrichment factor
• tritium recovery factor