Cross-validation of standardisation techniques at ANSTO using cobalt-60 and learnings from the presence and identification of non-gamma-ray emitting impurities

W M van Wyngaardt; A H H Bowan; E L Clark; C M B Keevers; M L Smith; M Zarifi; A Stopic

doi:10.1016/j.apradiso.2023.111027

Cross-validation of standardisation techniques at ANSTO using cobalt-60 and learnings from the presence and identification of non-gamma-ray emitting impurities

Appl Radiat Isot. 2023 Nov:201:111027. doi: 10.1016/j.apradiso.2023.111027. Epub 2023 Sep 16.

Authors

W M van Wyngaardt¹, A H H Bowan², E L Clark², C M B Keevers², M L Smith², M Zarifi², A Stopic²

Affiliations

¹ Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, 2234 NSW, Australia. Electronic address: freda.vanwyngaardt@ansto.gov.au.
² Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, 2234 NSW, Australia.

PMID: 37748217
DOI: 10.1016/j.apradiso.2023.111027

Abstract

To fulfil the technical requirements for accreditation to ISO/IEC 17025, the end-to-end validation of all processes associated with standardising ⁶⁰Co, including gravimetric source dispensing, primary standardisation by the 4π(LS)β-γ coincidence and live-timed anti-coincidence extrapolation techniques, and impurity determination were performed and documented. Pure-beta-emitting impurities in a ⁶⁰Co stock solution were identified. The impact of such impurities on measurement by liquid scintillation counting and comparison in the ESIR are discussed. A fresh ⁶⁰Co source was produced, standardised, and compared using the SIR.

Keywords: 4πβ-γ coincidence; 4πβ-γ live-timed anti-coincidence; Cobalt-60; Extended international reference system; ISO/IEC 17025; Liquid scintillation counting; MTR2; Pure-beta-emitting impurity; Radionuclide metrology.