Development of reference material for quality control of uranium analysis in marine sediments

Environmental radioactivity monitoring is strengthening due to public concerns over radioactive contamination since the Fukushima nuclear power plant accident. Therefore, various research laboratories, institutes, and universities have been conducting environmental radioactivity surveys around nuclear power plants (NPPs). However, the reliability of the results continues to trigger controversy in society. This study was conducted to develop reference material (RM) for the quality control of ²³⁸U and ²³⁴U analyses in marine sediments. The RM was prepared according to ISO Guides 31, 34, and 35. A homogeneity test of the marine sediment RM was implemented by analyzing two batch samples from ten bottles using multiple acid digestion and alkali fusion, respectively. We found that the ²³⁸U and ²³⁴U reference values of the RM were 43.0 ± 1.7 Bq kg^-1(k=1) and 41.5 ± 1.9 Bq kg^-1(k=1), respectively. This marine sediment RM will be useful for the quality control of analytical methods for similar samples and proficiency tests.