Abstract: This study analyzed the assessment results of the detection capability of gross α and gross β radioactivity in water in Yancheng from 2019 to 2024, with the aim to sort out the experiences and deficiencies, and to further improve the detection capability of the laboratory and ensure the accuracy of the detection results. From 2019 to 2023, the standard curve method (GB/T 5750.13—2006) was used. In 2024, the study transitioned to the thick-source method (GB/T 5750.13—2023) for simultaneously determining gross α and β radioactivity concentrations. Referring to the national standard "Conformity Assessment-General Requirements for Proficiency Testing" GB/T 27043—2012, results were valuated using Z-scores and the influencing factors were analyzed. All Z-scores for gross α (ranging 0.11-0.73) and gross β (ranging 0.17-1.67) measurements showed satisfactory performance (Z≤2.0), with outstanding results in 2020 and 2022. After accounting for influencing factors such as crosstalk ratios and branching ratios of gross β, the Z-scores aligned more closely with the reference values. Through systematic reviews of analytical procedures and to continuously improve detection capability, the detection accuracy and reliability of radionuclides in water samples has notably been enhanced.

Key words: radiological analysis, gross α radioactivity, gross β radioactivity, water samples