| With the development and utilization of nuclear power technology after the end of World War ?,according to the statistical data of IAEA,442 nuclear power units are currently in operation,and the nuclear power unit under construction is 6,among which,the nuclear power units in transit account for more than 16%of the worldundefineds total electricity.On the occasion of the large-scale development of nuclear energy,there is a large number of nuclear facilities in the early nuclear industry system that are relatively unripe for the test or technology,including the research reactor for scientific research,the nuclear facilities of the military industry,the nuclear power experiment pile and the demonstration pile built for the purpose of verifying the related technologies,etc.,from the design life,The units of these facilities have basically reached the design life and must proceed to the decommissioning disposal stage as early as possible.According to the relevant data statistics of IAEA and NEA,about 2800 nuclear power plant units in the future need to go into the decommissioning disposal The estimation of the quantity of radioactive reserves is one of the most important work of the decommissioning of nuclear facilities.It is of great practical significance to provide the necessary reference materials for the decommissioning of the nuclear facilities.(1)It is an important basis for the determination of the decommissioning plan and the design of the decommissioning project.can provide the basis for selecting the correct retirement operation technology and method,such as the decontamination method,the removal technology and the like;and(2)providing the technical reference basis for the long-term radiation measures of the working personnel,the public and the environment;(3)Provide reference for the management and disposal of radioactive waste at different levels of radiation.In this paper,by taking the XX nuclear power unit as an example,the field investigation on the source project of the project nuclear power unit is carried out by using the radiation detection technology,and the estimation of the radioactive reserve items is carried out,and the neutron fluence rate of the fine components in the reactor is calculated based on the Monte Carlo software MCNP.then the activity calculation is carried out by the ORIGEN2 program,the primary system and each sub-system pollutant item are estimated and analyzed,the system and the equipment structural parameters are combined,the radioactive retention amount of the core and the neutron activation component and the pollution device is calculated,In comparison with that measurement data,the calculation method and the model are more reasonable.The total activity of the radioactivity in 2018 is 8.44E 17Bq,and the total activity of the core and neutron activation component is 8.42E 17Bq,and the total activity of the contaminated equipment is 1.67E 15Bq.During the first 10 years of the shutdown,the total activity of the activated pollutants decreased linearly due to the decrease of the self-decay of a large amount of radioactive 55Fe,and the total activity of the activated pollutants was reduced by 100 years,and the total activity of the pollutants was reduced to 5.19 E 06Bq,55Fe to 9.55 E 03 Bq,and 54Mn to 9.69E-22Bq,and the total activity of the activated pollutants was reduced to 9.69E-22Bq.The main pollution nuclide is 63Ni,59Ni.At this time,the effect of the radioactive nuclide self-decay is gradually reduced,and the measures of other ways need to be taken into account.The key of the safety protection is 60Co.In these main activation products,the high-energy X-ray of 60Co has a large environmental impact on the periphery of the facility,so it is necessary to set up the corresponding shielding layer according to its activity.In addition,it is also necessary to take into account the hazard of the nuclide in the pollutant,and 60Co belongs to the high toxicity.54Mn and 63Ni are of moderate toxicity,which also need to be considered in the follow-up. |
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