Analysis of tritium activity concentrations in urine and internal dose assessment for nuclear power plant workers

Abstract

ObjectiveTo investigate the activity concentration of tritium in urine of nuclear power plant (NPP) workers, in order to evaluate the occupational exposure levels. MethodsThree chosen NPPs were respectively located in southern, southeastern and northeastern China. Workers involved in operating, service, nuclear cleaning, chemical analysis, health physics, technical support, among others were randomly selected as the research targets, and 69 urine samples of no less than 50 ​mL were collected. The oxidative distillation method was used to pretreat the urine samples, and the activity concentration of tritium in distillate was then measured using liquid scintillation counter. The formula for the committed effective dose was also applied used to estimate the internal doses. ResultsThe highest tritium activity concentrations in urine samples from three NPPs were 2412.7, 6351.4, and 478.7 Bq/L, respectively. Correspondingly, the internal doses due to tritium intake were 1.8, 4.8 and 0.4 ​μSv, respectively. ConclusionsThe urine tritium activity concentration of workers varied greatly dependent on their job categories. The values for urine tritium radioactivity concentrations of workers involved in health care, nuclear cleaning and maintenance were generally higher than those for other job categories. The difference in urine tritium activity concentration mainly came from the different exposure time and tritium concentrations. From the dose assessment results, the internal dose caused by tritium intake did not exceed the public annual effective dose limit.