Journal of Nuclear Fuel Cycle and Waste Technology

Liquid scintillation counting (LSC) efficiency for tritium (³H) is calibrated using polynomial quench correction models and uncertainty analysis. We employed a previously published dataset of ³H quench standards, covering a wide range of quench levels. Second-, third-, and fourth-order polynomial models were fitted to the calibration data based on the published relationship between the instrument’s quench index and ³H counting efficiency. This was intended to provide representative cases for uncertainty analysis, rather than to identify an optimal functional form. The propagated uncertainties were quantified across the quench range, revealing that the intermediate and high quench regions are particularly sensitive; small errors in quench or calibration yield disproportionately large efficiency uncertainties. In contrast, the low-quenching region exhibited a relatively minor uncertainty contribution. These results highlight the methodological importance of applying rigorous uncertainty propagation to ³H LSC efficiency calibrations. In particular, explicitly accounting for calibration-fit uncertainty via the law of propagation of variances ensures a more reliable activity estimation and alignment with modern metrological standards, which is crucial for the confident quantification of low-level ³H.

Keywords

Liquid scintillation counting (LSC), Tritium, Quench curve, Uncertainty, Transformed spectral index of the external standard (tSIE)