Optimization of a primary X‐ray filter for X‐ray fluorescence analysis of uranium and plutonium

When workers are wounded at a nuclear fuel handling facility, it is difficult to quantify actinide contamination through α‐particle counting because these particles are shielded by blood. To overcome this problem, we used X‐ray fluorescence (XRF) analysis with a handheld‐type device that is useful in cases where sampling is not allowed, such as in this study. In XRF analysis, a primary X‐ray filter made of metal foil is generally inserted between the X‐ray tube and the sample to attenuate the incident X‐ray at the energy region of the XRF signal for the target element. Doing so can reduce the background signal originating from the scattered radiation of the incident X‐ray. In this study, we aimed to optimize a primary X‐ray filter that facilitates simultaneous high‐sensitivity analysis of uranium and plutonium in a wound. For this purpose, XRF measurements were performed for a needle‐puncture wound model contaminated by U and Pu, and the relationship between the filter material/thickness and the detection limit was investigated. Optimizing the filter material/thickness of a given target element was found to improve the detection limit of the measurement by ~10%.