The paper presents the estimated doses to the population of six eastern districts of the Orenburg region, Russia, based on the results of a comprehensive radiation survey conducted in 2019 in 34 settlements with previously found elevated levels of activity concentration of natural radionuclides in tap water from ground water sources of drinking water supply. It is shown that the average individual annual effective dose due to all natural sources of ionizing radiation in 18 of 34 settlements corresponds to ‘elevated level’ of exposure due to natural sources according to established classification (from 5 to 10 mSv/year), and in another 7 settlements to ‘high level’ (over 10 mSv/year) with radon being the main contributor to the dose. Four settlements of Kvarkensky and Adamovsky districts, where the highest indoor radon concentrations had been found, were selected for a detailed survey, which included measurements of density of radon flux from the soil, radon concentration in soil gas, activity concentration of natural radionuclides in samples of building materials and in soil samples, and activity concentration of radon in tap water from groundwater sources of drinking water supply. Results of the detailed survey proved that the main source of radon in the buildings was the soil gas infiltration; compared to it, the contribution of waterborne radon release was insignificant.
The paper presents results of a comprehensive radiation survey conducted in 2019 in six districts of the eastern part of the Orenburg region in 37 settlements with previously found elevated levels of activity concentration of natural radionuclides in tap water from groundwater sources of drinking water supply. The survey included measurements of indoor radon concentrations and EEC in residential and public buildings, as well as measurements of ambient dose equivalent rate of gamma radiation indoors and outdoors. The survey revealed that annual average indoor radon EEC in many residential buildings in 23 settlements and public buildings in 25 settlements exceeded the hygienic norm (action level) of 200 Bq/m3 adopted in Russia for existing buildings. The highest values of annual average indoor radon EEC were obtained in residential buildings in Novovinnitskoe (1242 Bq/m3), Bratslavka (987 Bq/m3) and Anikhovka (942 Bq/m3) in Adamovsky district, and in public buildings in Kvarkeno (2291 Bq/m3) in Kvarkensky district, Karabutak (1114 Bq/m3) and Novovinnitskoe (923 Bq/m3) in Adamovsky district. The established hygienic norms in terms of ambient dose equivalent rate indoors and outdoors were not exceeded in the surveyed settlements. Results of the survey showed that the main reason for high indoor radon concentrations in residential and public buildings in the settlements of the eastern part of the Orenburg region is not related to the usage of tap water from groundwater sources of drinking water supply with elevated levels of activity concentration of natural radionuclides.
The article deals with the issues of normative and methodological support of radiation survey of buildings and structures to be demolished. It is noted that with the intensive growth of construction of dwellings and public buildings in large cities, former industrial territories with a significant number of facilities to be demolished are being included into the development zone. The radiation monitoring and sorting of industrial waste generated after the demolition of buildings is not feasible in practice. The expediency of radiation survey of buildings and structures to be demolished at the stage preceding their dismantling, as well as the need to develop and approve at the federal level the methodology of its implementation is substantiated. Recommendations for the assessment of radiation safety indicators of buildings and structures to be demolished are given. It is shown that if the value of ambient equivalent gamma dose rate in the buildings and structures to be demolished does not exceed 0.6 μSv/h, industrial waste generated after demolition of buildings and structures and containing only natural radionuclides are not a subject to any restrictions related to the radiation factor, since the value of effective activity concentration of natural radionuclides is guaranteed not to exceed 1500 Bq/kg and therefore the waste is classified as Category I in accordance with the Basic sanitary rules for the provision of radiation safety (OSPORB 99/2010).
The paper presents data on indoor radon concentrations in the buildings of children institutions in a number of regions of the Russian Federation. The results of detailed radon surveys in 132 buildings of children institutions in 85 settlements of six districts of the Leningrad Region conducted in 2018-2020 were analyzed. In 14 buildings of children institutions in the Leningrad region (10.5% of all surveyed buildings) the hygienic limit on the indoor radon EEC was exceeded, the maximum measured value of radon concentration in the premises of children institutions reached 2200 Bq/m3. It seems appropriate to extend the experience of cooperation between the Directorate of the Rospotrebnadzor for the Leningrad Region and the Saint-Petersburg Research Institute of Radiation Hygiene after Professor P.V. Ramzaev in conducting detailed radon surveys in children institutions on other regions of the Russian Federation that face problems with indoor radon.
To justify the decision on the necessity of the execution of the remediation actions or public safety measures as well as the correspondence of the remediated territories to the established criteria or reference levels it is necessary to correctly perform the assessment of the doses of the public residing in the zone of influence of the facilities of the nuclear and radiation legacy. Currently, there is no legislative document, regulating the doses of that category of the public. Based on the result of the regulatory documents and scientific publications on the radiation surveys of the contaminated territories and assessment of the doses to the public residing in the surveillance zone of the radiation facilities, on the radioactively contaminated territories and exposed by natural radionuclides, it was estimated that approaches, models and equations for the estimation of the doses from man-made and natural radionuclides can be applied for the public residing in the zone of influence of the facilities of the nuclear and radiation legacy. The number of control measurement points and samples for the radiation survey of the territories of the limited scale should be sufficient for the representative assessment of the doses to the public.
To justify the decision on the necessity of the execution of the remediation actions or public safety measures as well as the correspondence of the remediated territories to the established criteria or reference levels it is necessary to correctly perform the assessment of the doses of the public residing in the zone of influence of the facilities of the nuclear and radiation legacy. Currently, there is no legislative document, regulating the doses of that category of the public. Based on the result of the regulatory documents and scientific publications on the radiation surveys of the contaminated territories and assessment of the doses to the public residing in the surveillance zone of the radiation facilities, on the radioactively contaminated territories and exposed by natural radionuclides, it was estimated that approaches, models and equations for the estimation of the doses from man-made and natural radionuclides can be applied for the public residing in the zone of influence of the facilities of the nuclear and radiation legacy. The number of control measurement points and samples for the radiation survey of the territories of the limited scale should be sufficient for the representative assessment of the doses to the public.
Underground water is one of the sources of water supply and the most important mineral resources. The enrichment of natural groundwater with radium isotopes is a geochemical regularity, and their use a recognized source of additional exposure to the population and the environment. Forecast resources of groundwater in the territory of the Russian Federation are 869055 thousand m3/day. As of 01.01.2015, 15054 deposits (sections) of groundwater have been explored, of which 10556 are in operation. In the federal districts, the volume of extraction and extraction of groundwater varies widely. The percentage of groundwater in domestic and drinking water supply in 35 regions of the Russian Federation ranges from 70 to 100%; in more than 30 regions it exceeds 90%. A whole series of large cities provide water supply through the underground water. Underground waters, depending on the field of application, are divided into drinking, technical, heat power, industrial and medical. The formation of numerous areas with an increased content of natural radionuclides for all types of groundwater is largely determined by the volume of their use. Organized use of groundwater is preceded by special water treatment, where it is possible to form doses of exposure to those above permissible levels established in NRB-99/2009 and the formation of a mass of waste with an increased content of natural radionuclides. In many regions of the country, there is a prospect of a constant increase in the use of all types of groundwater and the creation of new enterprises, which will require monitoring and radiation and hygienic assessment. Particular attention should be paid to the use of associated waters of oil and gas fields that have the highest content of natural radionuclides among groundwaters as a promising source of mineral raw materials.
According to the Federal target program “Provision of the nuclear and radiation safety in 2016-2020 and up to 2030”, activities on the liquidation of the nuclear legacy are performed in the Russian Federation. The nuclear legacy includes mines, pits, industrial facilities, burrows and tailings of the uranium processing facilities (objects of uranium legacy), objects of extraction and processing of precious and rare elements and mineral ore, producing the wastes with the increased concentration of natural radionuclides. Due to the damage or lack of the barriers, preventing the distribution of radionuclides, natural radionuclides contaminate the environment and expose the population residing in closely located communities. Radionuclides of radium ( 226Ra and 228Ra), radon (222Rn) and their daughter have the main contribution to the doses and corresponding radiation risks to the public residing in a vicinity of such facilities. According to the Russian legislative documents, exposure of the public residing in the area of location of the objects of the uranium legacy and objects and territories, contaminated by the natural radionuclides due to the past activities of the non-nuclear facilities is attributed to the natural exposure with the subsequent compliance to the requirements of NRB 99/2009 and OSPORB 99/2010 on limitations of natural exposure. The main direction of the use of the objects and territories contaminated by the natural radionuclides due to the past activities of nuclear and non-nuclear facilities is their unlimited use for the industrial purposes. The main criteria for the unlimited use of remediated areas and territories of buildings and constructions are the requirements of NRB-99/2009 and OSPORB-99/2010 for the construction of the residential and public buildings. The criteria of NRB-99/2009 and OSPORB 99/2010 for the industrial buildings would be applied for the use of the remediated areas and territories of buildings and constructions with the residual contamination by the natural radionuclides.
The first 5–7 years of the period under review in the history of the Natural Sources Dosimetry Laboratory happened to be in very hard period, which had a time the entire country. A severe funding reduction of the Institute in the 90-s created a threat of loss of the most active and highly professional middle-aged specialists. In these conditions, the only and the most efficient way to maintain Institute as a scientific establishment was to organize the Federal Radiological Center under the guidance of Dr. A.N. Barkovskiy. The Federal Radiological Center consisted of the all physical laboratories, including the Natural Sources Dosimetry Laboratory, without government funding. Nevertheless, as it is shown below, this period was the most fruitful for theoretical and experimental researches, and for development of legal documents and instructional guidance documents. Over these years, more than 10 sanitary regulations and hygienic standards, and more than 20 guidance documents were developed and implemented. Doses of the population due to the natural exposure data-collecting system on the base of federal statistical observation №4-DOZ form were designed. At this period, the first Federal Target Program «Radon» and the System of radiation and hygienic passportization of organizations and territories were developed and authorized. Dr. E.M. Krisiuk was fully engaged in these activities. In these years a great number of non-nuclear companies were examined. Large-scale studies of levels of exposure of the population on specific territories were conducted. The paper examines a summary of the main results, which were obtained in the most important areas of research and practical studies in the period under review.
The results of the radon screening in the premises of the preschool and school institutions in the Leningrad region are analized. The data were obtained from measurements of radon volume activity by the integral method. As objects of control were selected the old buildings built before 2000 and relatively new buildings. It is shown that the territory of the Leningrad region is highly heterogeneous by the potential radon hazardous. The highest levels of radon were identified in the surveyed buildings in Boksitogorsk, Volosovo, Vyborg and Slantsy.
At the initial development stage of the Leningrad Research Institute of Radiation Hygiene natural sources dosimetry laboratory the experts focused at establishment of equipment and methodology. The following period of the lab activity was rather related to theoretical and experimental research which finally led to creation of a new in radiation hygiene field of work on standard protection of population irradiation caused by natural sources of ionizing radiation. The article describes the main results of the laboratory research of construction materials natural radioactivity and the subsequent substantiation of specifications on natural radionuclides content in them. There was parallel research of natural radionuclides transfer in the system “fertilizers→soil→plants” and further along the nutrition chain into the human body. In these works there were first obtained the quantitative data on coefficients of natural radionuclides transfer from fertilizers into agricultural plants, data on the natural radionuclides content in phosphate fertilizers of the main manufacturers, and the reference data on the natural radioactivity of arable soils. This research provided substantiation of a standard of natural radionuclides content in phosphate fertilizers. Important results were also received in a large-scale research of natural environment radioactivity and of technological processes of production, processing and use of mineral raw materials. During this research for the first time there were obtained the tool data on irradiation levels and structure of doses of non-uranium industries enterprises’ employees and on natural radionuclides balance parameters in different technologies.For the last two years of the considered period the laboratory was practically not engaged in its primary activity – the efforts of all laboratory and the Institute experts were focused at analysis of Chernobyl NPP accident consequences, research of man-caused environmental contamination and development of protective activities.
By this time in the Russian Federation there is collected a huge file of data describing the influence of all natural sources of ionizing radiation on population in municipal conditions. These data are collected and generalized in radiation hygiene passports of the Russian Federation for the last 16 years and in the reporting forms of federal statistical supervision No 4-DOZ “Data on doses of population irradiation due to the natural and manchanged radiation background” for a period of 14 years. These data are received by direct measurements of gamma radiation dose rate in the premises and in the open air on the territory of settlements. Measurements were made with the most different dosimeters; their technical and metrological parameters differ considerably. In this regard of certain interest is evaluation of this data reliability degree; that will help to find out the reasons of higher levels of the Russian Federation population external irradiation in comparison with average global dose values.In this article an attempt was made to evaluate reliability degree of data on the population external irradiation doses using the radiation hygiene passports of territories and reporting forms No 4-DOZ for the whole period of supervision. For this there was used the known dependence between the gamma radiation dose rate and natural radionuclides effective specific activity (AEFF) in inhabitancy objects. For this purpose there were used the data on average AEFF values of building raw materials and of local manufacture materials, which are presented in radiation hygiene passports of territories. Definition of design value of gamma radiation dose rate in the buildings and in the open air according to AEFF measurement data in building raw materials and in local manufacture materials actually enables to get an independent evaluation of the population external irradiation doses. Comparison of two evaluations of the population external irradiation levels enabled to reveal certain territories on which the population external irradiation doses are obviously overestimated or underestimated. It is proved that the specified population external irradiation dose values for certain entities and for the whole country are much closer to corresponding evaluations by foreign experts and to the average global levels.
