Method optimization and uncertainty budget calculation for difficult-to-measure 41Ca using ICP-MS/MS

Introduction Radioactive waste is the byproduct of different applications of radioactive materials such as nuclear power production, reactors decommissioning, medical treatments, scientific research, and industrial applications. It is important to characterize radioactive waste to ensure its safe management and disposal due to the radiation and toxicity risks it poses to humans and the environment. The waste produced during reactor decommissioning is largely composed of concrete, which contains calcium in high proportions.

Calcium-41 is specifically of interest when it comes to decommissioning waste characterization, seeing that it is a long-lived (half-life t1/2 = 103,000 years), highly bioavailable through rapid migration in groundwater. Calcium-41 is formed by neutron activation of Ca-40, and decays mainly via electron capture into stable K-41, releasing X-rays and Auger electrons during its decay. It is present in low amounts and is thus categorized as difficult-to-measure.

Destructive analysis of Ca-41 can be done using liquid scintillation counting (LSC) or tandem inductively coupled plasma-mass spectrometry (ICP-MS/MS) which are available for routine analyses. However, Ca-41 needs to be separated from potential interferences when it comes to both techniques. During this work, the analytical method currently available for purification and analysis of Ca-41 will be optimized to be able to achieve a lower detection limit.

Furthermore, an overall uncertainty budget will be determined. Objectives The work on this project can be summarized into two objectives: Optimize the currently available Ca purification method to achieve lower detection limit for the analysis of Ca-41 using ICP-MS/MS.

Determine the overall uncertainty budget of the optimized analytical method. Determine uncertainty budget for ICP-MS analysis and compare different ways of calculation.