Abstract: Factors that affect the detection limit of tritium measurement with liquid scintillation counter are identified, screened and analyzed quantitatively in this article. With adoption of electrolysis enrichment, an optimized solution to lowering detection limit is presented. Above influential factors are verified individually by well designed experiments. It shows that the detection limit could be reduced to 0.87 Bq/L by choosing counting channels, background water, material of vial, ratio of sample and cocktail adequately without increasing workload, and further to 38.5 mBq/L if electrolysis enrichment process is used.

Key words: liquid scintillation, tritium, detection limit, electrolysis enrichment