Liquid scintillation counting of environmental radionuclides: a review of the impact of background reduction

Abstract

Liquid scintillation counting (LSC) supports a range of environmental science measurements. At Pacific Northwest National Laboratory, we are constructing an LSC system with an expected background reduction of 10-100 relative to values reported in the literature. In this paper, a number of current measurement applications of LSC have been considered with an emphasis on determining which aspects of such measurements would gain the greatest benefit: improved minimum detectable activity (MDA), reduction in sample size, and reduction in total analysis time.

Rapid method to determine 89/90Sr in steel samples

“…There continues to be significant improvements in instrument technology, where lowering the background in liquid scintillation counting is of particular interest. Douglas et al [20] at Pacific Northwest Nation Laboratory (Richland, WA, USA) have been evaluating ways to lower backgrounds in a LSC system, critical for low level environmental measurements. This includes optimization of coincidence counting electronics, construction with low background materials and perhaps even a shallow underground location.…”

Radiometric techniques for the detection and assessment of tritium in aqueous media - a review

“…In the case of LSC, it optimises the interaction between the low-energy βparticles and scintillant by combining them in a cocktail. Typical performance for LSC techniques in the analysis of environmental samples demonstrates a MDA of the order of 1  10 -4 Bq g -1 for a counting duration of around 3-5 hours and detection efficiency of 60% [154], [87]. However this may require the enrichment of the samples to an enrichment factor of 20, which takes up to 6 days to achieve [154].…”

In situ beta-gamma separation algorithm for cost-effective assessment of radioactive waste resources

“…Table 4 shows the calculation results from using the suggested method. The beta-ray counting fractions for each scintillator were calculated using Equations (9) to (12). Because BGO is much more sensitive than plastic to gamma rays, the beta-ray counting fractions for the BGO scintillators were much lower than those of the plastic scintillators.…”

“…The radioactivity of pure beta emitters can be measured using liquid scintillation counters (LSC) owing to their high efficiency for low‐energy beta rays . To analyze the radioactivity of purely beta‐emitting nuclides using LSCs, the sample must be pre‐treated: this procedure includes high‐temperature oxidation for a few hours and the collection of radioactive gas in a solution . Moreover, it includes an organic scintillator cocktail that generates liquid organic waste even though the LSC method with high‐temperature oxidation allows the measurement of an environmental sample with extremely low levels of radioactivity.…”