Solid-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 E_t causes a tritium memory effect in the system.

This study aims to reduce the tritium contamination caused by high-activity tritium samples during calibration.

First, 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 E_d, the tritium enrichment factor (E_d)^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.

The 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.

The 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.