Quality control of uranium concentration measurements

Abstract

Quality assurance and quality control are necessary to ascertain the output of any instrument with a certain level of confidence and maintain the measurement process in a state of statistical control. Data generated by three laser fluorimeters, used for analysing mass concentration of total uranium in liquid samples, were used in the present study. Erroneous data values, called outliers, were detected by Dixon test, Discordance outlier test, Rosner outlier test and Box plot. The distribution fitted to the data, was tested by Kolmogorov–Smirnov test, Chi-square test and Shapiro–Wilks test. From Shewart Control Charts it was concluded that the instruments were not in statistical control and an instrumental problem existed. The instrumental problem was solved and the instruments were subjected to quality control exercise again. Statistical parameters of the data from the detectors were compared before and after servicing. The improvement of the quality of detector output was evident.