Comparison of tritiated-water standards by liquid scintillation for calibration of a new Standard Reference Material®

Abstract

A new National Institute of Standards and Technology (NIST) tritiated-water ((3)H-labeled oxidane) standard was prepared and calibrated. It is the 17th in a series of linked standards since 1954 and will be disseminated as Standard Reference Material® SRM 4927G, having a massic activity of 544.2kBqg(-1), with an expanded (k=2) relative standard uncertainty of 0.96%, at a Reference Time of 1200 EST, 1 May 2015. The calibration is based on relative liquid scintillation (LS) measurements using quench-varied efficiency tracing with two previous 1999 issues, viz., SRM 4927F and 4926E. Measurement comparisons were also made with respect to a 1994 tritiated-water French national standard and to a tritiated-water solution measured by 19 laboratories as part of an international measurement comparison organized by the Bureau International des Poids et Mesures (BIPM) in 2009. Confirmatory measurements for the massic activity of both SRM 4927F and 4927G by a triple-to-double coincidence ratio (TDCR) technique were also made.

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

“…To combat the latter two points, by 1979 commercially available standards were marketed in the form of micro-gram quantity compounds that could be dissolved in the vial to expediate the ISM process [50]. Periodic comparisons of a wide range of tritium standards for LSC have demonstrated apparent consistency between the standards [51], [52]. The user must be careful in the choice of standard for use in ISM, factors effecting the decision include: it must be radiologically distinct from the sample, clearly resolved in the data output, have a suitably long half-life, be readily available, and ideally is eluted following analysis.…”

Primary standardization of 224Ra activity by liquid scintillation counting

“…For CNET, efficiency variation was achieved by chemical quenching with nitromethane and all 224 Ra sources were measured against matched 3 H sources. The 3 H sources were prepared using a gravimetric dilution of NIST tritiated-water (Hydrogen-3) standard SRM 4927g (NIST 2015;Collé et al, 2016).…”