Applicability of a 100-mL Polyethylene Vial for Low-Level Tritium Measurement Using a Low-Background Liquid Scintillation Counter

For low-level tritium measurements using a liquid scintillation counter, scintillation vial selection is important. The applicability of polyethylene (PE) vials was studied. Three types of vials were tested: (1) 100-mL perfluoroalkoxy alkane (PFA) fluorine resin vials, (2) 100-mL PE vials, and (3) 145-mL PE vials. Ultima Gold LLT was the reference liquid scintillator in this study. The background counts for these vials were found to be 2.5 counts per minute. Tritiated water of 1.5 Bq‧mL−1 was employed as an internal standard to determine the counting efficiency. The counting efficiencies for the 100-mL PFA, 100-mL PE, and 145-mL PE vials were estimated to be 17%, 16%, and 13%, respectively. The lower limits of detection of these vials for a counting time of 100 min were 1.45 Bq‧L−1 for 100-mL PFA vials, 1.54 Bq‧L−1 for 100-mL PE vials, and 1.47 Bq‧L−1 for 145-mL PE vials. Thus, these vials demonstrate similar performances for tritium measurements.