Year
2025
Abstract
Under the environmental sampling program for International Atomic Energy Agency (IAEA) safeguards, the development of age dating, also known as radiochronometry, is an area of intense research to bolster safeguards analytical support. The measurement of ‘model ages’ derived from the ingrowth of parent-daughter isotope pairs found in trace amounts at nuclear facilities provide a type of ‘clock’ to indicate the most recent purification or production date of a safeguarded material. Current radioanalytical and mass spectrometric measurement techniques employed for age dating struggle to determine model-ages of freshly separated materials due to the sub-femtogram sample sizes of isotopes of interest present in environmental swipe samples. Despite the reported superiority of Accelerator Mass Spectrometry (AMS) in its sensitivity to trace amounts the actinides, it has rarely been investigated in the application of radiochronometry for safeguards. This paper investigates the practicality and usefulness of employing AMS for age dating, using the Australian Nuclear Science and Technology Organisation’s (ANSTO) 1MV VEGA accelerator as a case study. Results demonstrate that the superior sensitivity of AMS will make it practical for age dating of freshly separated materials. This application is particularly suited for plutonium dating, whilst uranium age dating is limited by contamination risks due to large isotopic abundance ranges collected in swipe samples. AMS has a unique potential for age dating recently separated plutonium of both low and high burnup obtained by environmental swipe sampling, incapable by current means. By applying AMS to accurately verify the production age of plutonium at various production facilities, especially those of recent operation, this additional capability would strengthen the IAEA's safeguards analytical capabilities.