Determination of total tritium in urine from residents living in the vicinity of nuclear power plants in Qinshan, China

Tritium in urine from members of the general public and occupationally exposed workers in Lund, Sweden, prior to operation of the European Spallation Source

A powerful neutron source, the European Spallation Source (ESS), is currently under construction in Lund, Sweden (~90 000 inhabitants). Levels of tritium (³H) in urine were estimated in members of the public in Lund and employees at the ESS using liquid scintillation counting, to obtain baseline levels before the start of operation of the ESS. These were compared with levels in other occupationally exposed radiation workers. Both the spallation reaction in the ESS tungsten target and the activation of various materials by the protons produced by the 5 MW linear accelerator will generate tritium, which will be released into the atmosphere mainly as tritiated water (HTO). Urinary HTO activity concentrations were determined in a total of 55 individuals belonging to four different categories: ESS employees, neighbours of the ESS, members of the general public in Lund and exposed workers from other facilities. The participants were asked to provide information on their beverage intake the day before urine sampling. The urine samples were filtered on activated charcoal and distilled before analysis. The effect of sample preparation on the isotope fractionation of urine samples was investigated by isotope ratio mass spectrometry (IRMS) of ²H/¹H, which showed no influence. IRMS was also used to investigate if the ratio between the stable hydrogen isotopes (²H/¹H) could provide useful data of the origin, and hence the tritium concentration, of various types of drinking water. Urinary HTO activity concentrations determined using liquid scintillation counting (LSC) were found to be below the minimum detectable activity (MDA) of 2.1 Bq⋅L^-1 for most of the participants. Five of the workers actively handling organic tritiated material were found to have activity concentrations between 3.5 and 11 Bq⋅L^-1, which were higher than the average value in local tap water of 1.5 ± 0.6 Bq⋅L^-1. The results will be used to evaluate the radiological impact on the population from future releases of tritium resulting from the operation of the ESS.

Monitoring of Tritium Internal Exposure Doses of Heavy-Water Reactor Workers in Third Qinshan Nuclear Power Plant

To analyze the tritium internal exposure dose of workers in the Third Qinshan Nuclear Power Plant over the past 15 years. Urine samples provided by workers are tested directly to analyze the tritium concentrations and estimate internal exposure dose. Since 2004, an average of approximately 1600 workers have been monitored annually, with an average annual monitoring frequency of approximately 11 000. Since 2004, the average annual collective dose of tritium internal exposure was 149.62 person·mSv, accounting for 19.07% of the total annual collective dose. A total of 18 workers’ annual individual internal tritium radiation doses exceeded 2 mSv, of which 5 workers’ internal tritium radiation doses in a single intake exceeded 2 mSv. The occupational population with the largest total internal tritium radiation doses consists of maintenance personnel, fuel operators, and radiation protection personnel, whose collective doses of internal exposure account for 75.51% of the total collective doses within the plant. Over 15 years of operation, the internal tritium radiation doses of workers in the Third Qinshan Nuclear Power Plant have been strictly controlled within the national regulatory limit and power plant management target, ensuring the health and safety of the workers.

Tritium internal dose estimation from measurements with liquid scintillators

Tritium may exist in several chemical and physical forms in workplaces, common occurrences are in vapor or liquid form (as tritiated water) and in organic form (e.g. thymidine) which can get into the body by inhalation or by ingestion. For internal dose assessment it is usually assumed that urine samples for tritium analysis are obtained after the tritium concentration inside the body has reached equilibrium following intake. Comparison was carried out for two types of vials, two efficiency calculation methods and two available liquid scintillation devices to highlight the errors of the measurements. The results were used for dose estimation with MONDAL-3 software. It has been shown that concerning the accuracy of the final internal dose assessment, the uncertainties of the assumptions used in the dose assessment (for example the date and route of intake, the physical and chemical form) can be more influential than the errors of the measured data. Therefore, the improvement of the experimental accuracy alone is not the proper way to improve the accuracy of the internal dose estimation.

Determination of tritium concentrations in humans before the development of a nuclear power plant in Turkey

The most widely used method to determine the level of tritium in humans is testing urine. Tritium concentrations in urine samples of 100 persons aged 18-66 years selected randomly from a pilot region in Turkey were analysed. The average activity concentration of urine samples was 4.66 ± 1.94 Bq L(-1) and the maximum activity concentration was 27.91 Bq L(-1). The minimum detectable activity was 2.38 Bq L(-1). The annual effective dose from tritium was also evaluated on the basis of the measurement results and reference values recommended by the International Commission on Radiological Protection. The effective doses for males and females were 4.56 and 3.54 nSv, respectively. These results were lower than the permissible annual effective dose for members of the public.