Screening Method of Uranium Contamination Levels in Concrete by Total Reflection X-Ray Fluorescence Analysis

Abstract

In the dismantling of nuclear facilities or the decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station, it is necessary to evaluate the material contamination levels by nuclear fuels and fission products. In this study, we propose a method for screening the uranium contamination level of concrete surfaces in such a scenario. Using this method, the concrete surface is scraped, and its components are acid-eluted. Uranium is extracted by the solid-phase extraction method, and total reflection X-ray fluorescence analysis is performed. We concluded that it is appropriate to use 0.5 g of concrete for analysis because the solid phase extraction recovery decreases owing to the matrix effect when using larger concrete samples. The relationship between the added uranium content and that determined in the eluate showed a straight line with a slope of almost 1; whereas uncontaminated concrete also contains uranium, the vertical intercept has a significant value. The lower limit of detection was 37 ng, which indicates that the uranium contamination can be detected when an increase in uranium content exceeding 37 ng is observed in the acid eluate for concrete suspected of contamination compared to that for uncontaminated concrete.