Rapid extraction and assay of uranium from environmental surface samples

Environmental sampling to detect trace nuclear signatures is key component of international nuclear treaty enforcement. Herein, we explored rapid chemical extraction methods coordinated with measurement systems to provide faster, simpler assay of low level uranium from environmental samples. A key problem with the existing analytical method for processing environmental surface samples is the requirement for complete digestion of sample and sampling material. This is a time-consuming and labor-intensive process that limits laboratory throughput, elevates analytical costs, and increases background levels. Promising extraction methods were competitively evaluated for their potential to quickly and efficiently remove different chemical species of uranium from standard surface sampling material. A preferred combination of carbonate and peroxide solutions is shown to give rapid and complete form of uranyl compound extraction and dissolution. This simplified and accelerated extraction process is demonstrated with standard sampling material to be compatible with standard inductive coupled plasma mass spectrometry methods for uranium isotopic assay as well as rapid screening techniques such as X-ray fluorescence (XRF). Rapid extraction of the entire swipe is shown to allow efficient XRF assay of all collected material for simple, fast, nanogram-level XRF assay of the sample. The new methods have direct application in the support of nuclear safeguards treaty enforcement efforts as well as health and safety monitoring. The general approach described may have applications beyond uranium to other trace analytes of nuclear forensic interest (e.g., rare earth elements and plutonium) as well as heavy metals for environmental and industrial hygiene monitoring.