Browsing by Author "Medley, P"

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    Comparison of radium-228 determination in water among Australian laboratories
    (Elsevier, 2017-11) Zawadzki, A; Cook, M; Cutmore, B; Evans, F; Fierro, D; Gedz, A; Harrison, JJ; Loosz, T; Medley, P; Mokhber-Shahin, L; Mullins, S; Sdraulig, S
    The National Health and Medical Research Council and Natural Resource Management Ministerial Council of Australia developed the current Australian Drinking Water Guidelines which recommend an annual radiation dose value of 1 mSv year−1. One of the potential major contributors to the radiation dose from drinking water is radium-228, a naturally occurring radionuclide arising from the thorium decay series. Various methods of analysing for radium-228 in water have been established and adapted by analytical radiochemistry laboratories. Seven laboratories in Australia participated in analysing radium-228 spiked water samples with activity concentrations ranging from 6 mBq L−1 to 20 Bq L−1. The aim of the exercise was to compare and evaluate radium-228 results reported by the participating laboratories, the methods used and the detection limits. This paper presents the outcome of the exercise. Crown Copyright © 2017 Published by Elsevier Ltd.
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    Optimisation of neodymium hydroxide micro-precipitation of polonium-210 for alpha spectrometry source preparation
    (South Pacific Environmental Radioactivity Association, 2022-11-29) Medley, P; Patterson, S; Howell, NR; Froehlich, MB
    Co-precipitation of actinides with lanthanide hydroxides is a suitable technique to prepare high resolution sources for alpha spectrometry. One such technique has been adapted and optimised for co-precipitation of 210Po with Nd(OH)3. Chemical recovery greater than 90%, with a resolution less than 40 keV at full-with-half-maximum (FWHM) was achieved. The method can be faster, less expensive and less labour intensive than routine techniques using auto-deposition of Po onto Ag. Owing to co-precipitation of several metals with Nd(OH)3, including Fe and alpha emitting radionuclides, radiochemical separation of 210Po from the sample matrix is required for this method to be effective. The technique, however, does effectively separate Po from Cu, and is thus highly suited to samples where complete radiochemical separation from Cu is difficult to achieve, such as copper concentrates. The method also achieves 94±2% separation of 210Po from Pb. A common technique for measurement of 210Pb uses an initial separation of 210Pb from 210Po and then allows time for ingrowth of 210Po. A second radiochemical separation is then performed for 210Po, measurement of which is used to infer the initial activity concentration of 210Pb. Effective separation of 210Po and 210Pb using Nd(OH)3 co-precipitation can therefore simultaneously radiochemically separate these two isotopes and prepare 210Po for alpha spectrometry. Thus, reducing radiochemical processing for 210Pb analysis when measured through ingrowth of 210Po. As Bi is also co-precipitated with Nd(OH)3 with this method, a correction factor for contribution from 210Bi to the 210Po activity measured may be required. Biological samples were processed using microwave-assisted digestion followed by radiochemical separation for 210Pb and 210Po. Co-precipitation of 210Po with Nd(OH)3 was done on the 210Po fraction from both separated fractions, a delay after radiochemical separation for the 210Pb fraction was allowed for ingrowth of 210Po. Results from these measurements will be presented.