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In this study, the natural radioactivity in pit-water and paddy soil around a decommissioned uranium mine in eastern China was investigated. The gamma radiation absorbed dose rate, annual effective dose equivalent, radium equivalent activity, and radiation hazard index were calculated, and their spatial distribution was presented. The profile distribution of the activity concentrations of radionuclides was also investigated for the possible deposition effect. The radioactivity accumulation in the paddy-soil due to the irrigation was further discussed. It was shown that the accumulation of radioactivity in the paddy soil was limited from the irrigation.

Eight liquid effluent samples from nuclear power plants (NPP) were analyzed for 63Ni, 131I, and gamma radionuclides using methods with low detection limits. The sum of the radionuclides activity concentrations of the effluent samples from NPPs A and B were closely lower than the operator’s results with a maximum of decreasing to 29%, while from NPP C were much lower with a maximum of decreasing to 5%. The unlisted radionuclides account for 5.0–889%. It was indicated that the statistics method of the discharge amount could be established based on a regular investigation of the radionuclide characteristics based on analytical methods with low limits of detection.

An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities.

The analytical method for organically bound tritium (OBT) was developed in our laboratory. The optimized operating conditions and parameters were established for sample drying, special combustion, distillation, and measurement on a liquid scintillation spectrometer (LSC). Selected types of OBT samples such as rice, corn, rapeseed, fresh lettuce and pork were analyzed for method validation of recovery rate reproducibility, the minimum detection concentration, and the uncertainty for typical low level environmental sample was evaluated. The combustion water recovery rate of different dried environmental sample was kept at about 80%, the minimum detection concentration of OBT ranged from 0.61 to 0.89 Bq/kg (dry weight), depending on the hydrogen content. It showed that this method is suitable for OBT analysis of environmental sample with stable recovery rate, and the combustion water yield of a sample with weight about 40 g would provide sufficient quantity for measurement on LSC.