Nuclear facility solid waste package radioactivity evaluation method and system

Abstract

The invention discloses a nuclear facility solid waste package radioactivity evaluation method and system. The method comprises the following steps: in a radioactive waste generation or treatment stage, establishing a shielding calculation waste model to calculate a dose rate contribution value of unit amount of easily-measured nuclide in the radioactive waste to a radioactive waste surface dose rate measurement position; calculating the activity of each radionuclide in the radioactive waste by combining the surface dose rate of the radioactive waste; after the radioactive waste is treated toform a waste package, correcting the activity of the easy-to-measure nuclide in the waste package according to the decay of the radionuclide to obtain the correction activity of each easy-to-measure nuclide in each radioactive waste, and summing the correction activities of the same easy-to-measure nuclide in all the radioactive wastes to obtain the activity of the easy-to-measure nuclide in the waste package. Compared with a traditional sampling laboratory radiochemical analysis and NDA method, the problem that waste package sampling and measurement are difficult is solved, and the measurement and evaluation result is higher in accuracy than that of the NDA method.

Description

technical field [0001] The invention belongs to the field of nuclear facility radioactive waste management, and more specifically, the invention relates to a method and system for evaluating radioactive activity of nuclear facility solid waste packages. Background technique [0002] In recent decades, the construction of the national nuclear industry and the development of nuclear energy have continued to carry out a large number of scientific research and production activities, and a large number of nuclear facilities have been established. With the rapid development of construction and operation, various radioactive wastes continue to be generated. After a large number of nuclear facilities built in the early stage have successfully completed various national tasks, in order to protect the environment and public safety, various nuclear facilities have been closed down and entered the decommissioning stage. In the future, more nuclear facilities will be decommissioned. The ...

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Problems solved by technology

The measurement accuracy of the TGS method is relatively ideal, and the application range is relatively wide. Especially for the measurement accuracy of the uneven material in the barrel, it is obviously better than other measurement methods, but the higher accuracy depends heavily on the number of measurements. Multiple measurements are used to solve the equation group. The decoupling process makes the measurement process more complicated and the measurement time is too long, which is not suitable for the measurement of a large number of waste packages in nuclear facilities

The traditional SGS method adopts the basic assumption that the radioactive nuclides and absorbing media are uniformly distributed in each layer of the radioactive waste in the storage container, which is not consistent with the actual process of nuclear facilities, and the types of radioactive waste packages actually produced are various , the distribution of materials and nuclides in the package is mostly uneven, and the medium and radionuclide distribution of any measurement object are different from the basic assumptions of the SGS method, especially in medium and high densities, extremely uneven nuclide distribution, and even "hot spots" For radioactive waste, the distribution of radioactive intensity and the density of the medium vary greatly with the spatial geometric position. If the same linear attenuation coefficient is still used to correct the self-absorption of the sample, it will inevitably cause a large error in the analysis results.

For samples with relatively uniform and small attenuation, the SGS method has an error range of 10% to 30%, and the error increases with the increase of attenuation; for samples with very uneven attenuation, the error may even exceed 500%, and the system The occurrence of errors cannot be automatically diagnosed

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