Development of compact electrolytic enrichment system for environmental tritium analysis

The new electrolytic enrichment system with compact glass cell was designed. Three (Ni-Fe-Ni) electrodes are used, and electrolysis is carried out at a rate of 2.45 g per h with constant current density of 120 mA per cm2. This enrichment system allows the enrichment for small, limited sample volumes (e.g. Tritiated Water (HTO) recovered from air). With an initial water volume of 100 ml, the tritium enrichment factor of 7 within 2 days and a detection limit of 0.12 Bq per L can be obtained by Liquid Scintillation Counter (LSC) measurement for 1000 minutes, which is better than the direct measurement with 50 ml sample water using large vial. It is also possible to perform the high enrichment process. The initial sample volume of 700 ml enriched for 12 days by manual refilling yields a tritium enrichment factor of around 43 and detection limit of 0.02 Bq per L for 1000 minutes of LSC measurement.