Inter Laboratory Comparison Exercise to Determine the Radionuclide Comparison of Three Mixed Biota Samples

The issue surrounding the shortage of reference materials has long been discussed and becoming progressively important as the nuclear industry faces the challenges of decommissioning, increasing the requirement for the analysis of a wide range of radionuclides in diverse sample types. To meet demand the radiochemical methods need to be flexible and robust whilst maintaining a high level of quality, essential to underpinning public and environmental safety in a highly regulated sector. Integral to the process of method development, validation, and performance evaluation is the use of reference materials which provide the confidence in the measurement. Currently there is an acute shortage of certified, solid, reference materials due to costs associated with production and availability of suitable material. An alternative to adopting the formal intercomparison exercise approach was explored by the UK’s Analyst Informal Working Group (AIWG). The members recognized the shortage of suitable, solid materials containing a range of alpha, beta and gamma emitters and identified three mixed biota samples. The molluscs, winkles and crustacea contained a mix of environmental activity level radionuclides (¹⁴C, ⁴⁰K, ⁹⁰Sr, ⁹⁹Tc, ¹³⁷Cs, ^239+240Pu, ²⁴¹Pu and ²⁴¹Am) and were dispatched to 12 laboratories in the UK and Europe in the Summer of 2017. Following analysis, using several techniques, the results were evaluated in terms of levels of precision, sensitivity and limits of detection. The results of the study showed all the radionuclides were successfully analysed by the laboratories to a level of precision and accuracy consistent with that achieved through routine analysis. The exercise demonstrated the viability and benefits of adopting the intercomparison exercise approach, which uses consensus values, to produce fit for purpose reference materials to practically address the shortage.