Abstract: In the analysis of radioactive samples, radionuclides decay correction methods could be classified into three different stages(types): correction for decay during the counting period, correction for decay prior to the starting time of counting, and the correction for decay during the sampling duration. Based on the law of radioactive decay, the principles of three different types of decay correction methods are explained. Aiming at the gaseous effluents monitoring and samples analysis in nuclear power plants, for the short half-life radionuclides of noble gases & iodines, the necessity of decay corrections which were applied to the specific activity results is analyzed and the decay correction factors of three different types are calculated. For gamma-ray spectrometry, experimental results reveal that the Minimum Detectable Concentration(MDC) of radionuclide is directly related to the decay corrections. The application scheme of decay corrections for gaseous effluents monitoring samples analysis in nuclear power plants is introduced and studied. For the short half-life radionuclides of noble gases & iodines, the monitoring analytical data deviation was reduced by the implementation of the reasonable conservative corrections scheme, and the conservativeness of statistical emissions could be ensured too.

Key words: nuclear power plant, gaseous effluents, decay corrections, short half-life radionuclides, noble gases, iodines, Minimum Detectable Concentration(MDC), emissions