Radiation doses received by workers during their movement within areas contaminated as a result of events and activities, leading to emergency or existing exposure situations, may provide a substantial contribution to total external exposure during remediation work. This paper describes an approach to minimise worker external exposure in these circumstances, based on graph theory. The paper describes several tasks, including: searching for a route with the lowest dose, searching for an optimal bypass with a given set of control points and searching for the optimal road network coverage. Classical graph theory algorithms have been used (Dijkstra’s algorithm, Chinese postman problem and travelling salesman problem). Algorithms for solving the above mentioned problems have been developed and were included in the information-analytical system for radiation safety. This software has been applied for optimisation of protection during remediation work at the Andreeva Bay site of temporary storage for spent fuel and radioactive waste in the Kola Peninsula, both in the context of existing exposure situations and improving the preparedness for emergency exposure situations.
The article presents estimates of radiation doses of technogenic exposure to personnel and the public due to the normal operation of radiation facilities, exposure to the public due to natural sources and technogenically altered radiation environment, and medical exposure of patients. The doses values were obtained using the Unified System of Individual Dose Control of the Russian Federation citizens for 2020. The authors have analyzed the data contained in the forms of state statistical observation No. 1-DOZ, No. 2-DOZ, No. 3-DOZ and No. 4-DOZ for 2020 submitted by the organizations and territories, the state sanitary and epidemiological supervision of which was carried out by Rospotrebnadzor and Federal Medical Biological Agency of Russia. In the article also were used data obtained within the framework of Radiation-Hygiene Passportization. In 2020, 19 737 organizations dealing with technogenic sources of ionizing radiation submitted forms No. 1-DOZ with the information on the doses to personnel with a total number of 230 318 persons, of which 230 318 persons belonged to the personnel group A and 21 303 persons belonged to the personnel group B. For these groups, the doses were assessed based on results of individual dosimetric control. In 2020, according to Unified System of Individual Dose Control of the Russian Federation citizens data, the average individual annual effective dose of technogenic exposure to the personnel group A was 1.11 mSv, and for the personnel group B it was 0.63 mSv. In 2020, 6 cases of exceeding the average annual effective dose limit (20 mSv) for Group A personnel and 18 cases of exceeding the average annual effective dose limit (5 mSv) for Group B personnel were registered. The total number of X-ray and radiological diagnostic procedures performed in the Russian Federation in 2020 exceeded 275.4 million, or 1.83 procedures per a citizen. The average annual effective dose of medical radiation exposure per one resident of Russia in 2020 was 0.81 mSv, and per procedure – 0.44 mSv. The average annual effective dose of radiation to residents of the Russian Federation from natural sources, according to all measurements for the period from 2001 to 2020, was 3.36 mSv. More than 59% of this dose is associated with the inhalation of radon and its progenies. The average individual annual effective radiation dose to residents the Russian Federation subjects in 2020 ranged from 2.47 mSv (Kamchatka Krai) to 9.06 mSv (Altai Republic) with an average value for the Russian Federation of 4.18 mSv. For eight subjects of the Russian Federation, the average individual annual effective dose to public in 2020 exceeded 5 mSv: the Republics of Buryatia (5.31 mSv), Altai (9.06 mSv), Tyva (6.31 mSv), Magadan (5.07 mSv) and Irkutsk (6.13 mSv) regions, Stavropol (6.31 mSv) and Zabaykalsky (8.19 mSv) krai and the Evreiskaya Autonomous oblast (6.77 mSv).
This paper deals with classification of dose distributions of nuclear workers based on antikurtosis (Q) and entropy coefficients (K) and their relationship presented in QK-diagrams. It is shown that determination of the most appropriate distribution to adopt, for a specific data set of a wide range of input data, requires building and analysing QK-diagrams for distributions of logarithms of individual doses. Actual dose distributions for emergency and occupational exposure situations were then considered, as well as doses for one day of work during clean-up and routine activities. It is shown that, in all cases, three types of distributions of logarithms of individual doses were present: normal, Weibull and Chapeau. The location of the representation point of a dose distribution reflects the degree of dose control of the group of workers whose individual doses are collectively displayed in the QK-diagram. The more the representation point of the analysed distribution of the logarithms of the individual dose of a given contingent of workers deviates from the point of the lognormal distribution, the more there was intervention in the process of individual dose accumulation. Thus, QK-diagrams could be used to develop a dose control function. It is shown that the hybrid lognormal distribution, which is widely used in the field of radiation safety, for the purpose of approximation of real dose distributions, is unable to satisfactorily describe many dose distributions arising in aftermath operations and occupational exposure.
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