Gamma Radiation Dose Rate Research Articles

САМОНАВЧАЛЬНІ НЕЙРОННІ КАРТИ В ЗАДАЧАХ ЕКОЛОГІЧНОГО МОНІТОРИНГУ

There is a certain problem in ecological monitoring of the environment state according to the measured values of a certain abiotic factor. Namely, how to build a continuous map of environmental pollution throughout the controlled area, based on the results of measurements carried out at a finite number of points inside the controlled territory. The aim of the work is to study the possibility of using the method of self organizing neural maps (SOM) for the problems of the ecological monitoring of the environment, and specifically for building an accurate continuous map of environmental pollution on the ground. The materials and methods of researches are the results of measurements the ambient equivalent of the continuous X-ray and gamma radiation dose rate on a territory of the historical center of Kharkiv has been used as research materials; processing of the obtained data by SOM's methods using MatLab 8.1 and STATISTICA 10 computer programs has been done. Results: in the process of 1000 self-learning cycles of a neural network of 100 initial active neurons randomly located on the controlled area map, 25 neural clusters have been obtained, the coordinates of the centers of which practically coincided with the 25 control points coordinates. A continuous map of the background radiation on the controlled area has been built. The accuracy of this map was no worse than 0.25 μR/hour. Conclusions: the possibility of using the SOM methods to build a continuous map of the level of environmental pollution on the ground based on the results of measuring the values of a certain abiotic factor in a finite number of points has been proven. It has been proven that this method is more accurate compared to the methods of regression mapping and cluster analysis, from which it is essentially different. The possibilities for a significant improvement in the accuracy of the method lie in increasing the number of initial neurons on the terrain map and the number of iterations during their training.

Особенности радиационного фона различных районов Санкт-Петербурга

Radiation safety takes an essential part in the megalopolises' ecological system. Nowadays the influence of radiation factor on the biosphere is considered one of the determining factors and it causes the necessity to monitor the environmental and radiation safety of the population. The aim of the study is a comparative assessment of the ambient equivalent dose rate (ADER) of gamma radiation according to automated radiation monitoring system (АSКRО) data and its own measurements in the South-Western district of St. Petersburg. The article presents an analysis of the radiation background of St. Petersburg over the past five years based on the data of the АSКRО, as well as the results of own measurements of the ADER in the South-Western district of St. Petersburg using the dosimeter-radiometer "Ecologist profi". When analyzing the radiation levels of various districts of St. Petersburg, it was found that the regions with a relatively higher level of ADER included the Central and South-Western regions. The results of our own meas-urements are comparable with the data from АSКRО; there are no significant differences be-tween the data samples. The results of the study show that the АSКRО data can be used for a general description of the radiation situation in certain areas of St. Petersburg, but they can not serve as a substitute for operational radiation control (monitoring). It is necessary to constantly control and monitor the radiation situation in the region in order to obtain information for timely detection of changes in the radiation situation and to prevent possible negative consequences of radiation exposure for the population and the natural environment.

The outcomes of functioning of the Unified System of Individual Dose Control of the Russian Federation citizens based on the 2019 data

The article presents results of the analysis of information on the doses of technogenic exposure of personnel and the population due to the normal operation of radiation facilities, exposure of the population due to natural sources and technogenically altered radiation environment, and medical exposure of patients. The data were obtained using the Unified System of Individual Dose Control of the RF citizens for 2019. The analysis was carried out on the basis of the data contained in the forms of state statistical observation No. 1-DOZ (personnel individual doses), No. 2-DOZ (emergency doses), No. 3-DOZ (patients’ exposure doses) and No. 4-DOZ (population exposure doses from natural and technogenically impacted background) for 2019 submitted by the organizations and territories, the state sanitary and epidemiological supervision of which was carried out by Rospotrebnadzor and FMBA of Russia. The article used data obtained within the framework of Radiation-Hygiene passportization. In 2019, 18430 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 247934 people, of which 227723 people belonged to the personnel group A and 20211 person to the personnel group B. For these groups, the doses were assessed based on results of individual dosimetric control. In 2019, according to the Unified System of Individual Dose Control data, the average individual annual effective dose of technogenic exposure to the personnel group A was 1.19 mSv, and for the personnel group B it was 0.64 mSv. The total number of X-ray and radiological diagnostic procedures performed in the Russian Federation in 2019 exceeded 306.5 million, or 2.09 procedures per a citizen. The average annual effective dose of medical radiation exposure per one resident of Russia in 2019 was 0.62 mSv, and per procedure — 0.31 mSv. The submittedforms No. 4-DOZ of the constituent entities of the Russian Federation for 2019 contained results of the measurements of dose rate of gamma radiation in 9179 wooden houses, 11,307measurements in low-rise stone houses, 121323 measurements in multi-storey stone houses and 229342 measurements in open areas. These also contained results of 3930 measurements of radon levels in wooden houses, 5071 measurements in low-rise stone houses and 46896 measurements in multi-storey stone houses, as well as the results of 19444 analyses of the levels of natural radionuclides in drinking water. 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 2019, was 3.36 mSv. The article provides Appendices with the final forms of Unified System of Individual Dose Controlfor the Russian Federation for 2019. Data for the forms have been obtained on the basis of summarizing the information contained in the forms of state statistical observation No. 1-DOZ, 3-DOZ and 4-DOZ of the constituent entities of the Russian Federation.

NATURALLY OCCURRING RADIONUCLIDES IN SOIL SAMPLES OF BURETI SUB-COUNTY OF KERICHO COUNTY KENYA.

The activity concentration of soil samples of Bureti sub-county was measured using thallium-activated sodium iodide detector. To ascertain the level of radiation hazard to the public, gamma radiation dose rates were also estimated. The average activity concentration due to 40K, 226Ra and 232Th for soil samples are 1164±70, 106±8 and 79±5 Bqkg-1, respectively. An average dose rate of 145±10 nGyh-1 was recorded, which is about 2.5 times higher than the world average value of 60 nGyh-1(UNSCEAR). On the other hand, an average outdoor effective dose of 0.35±0.02 mSvy-1 was measured, which is lower than the ICRP safety limit of 1 mSvy-1. This shows that the radiation hazards from naturally occurring terrestrial radionuclides in Bureti is low and therefore human radiation exposure is within the accepted limits.

Indirect assessment of internal irradiation from tritium decay on Lemna Minor duckweed

The response changes of the specific growth rate of Lemna minor duckweed was modeled using the logarithms of frond numbers on tritium activity concentration and gamma radiation dose from cobalt 60. The concept of average specific growth rate depends on the general exponential growth pattern, where toxicity is estimated based on the effect on the growth rate. One of the main questions of the effect of the radiation dose on duckweed is how to correlate the effect of beta radiation with the effect of any other radiation for modeling radiation on Lemna minor. Experimental data were extrapolated by utilizing the OECD guidelines.A linear relationship of absorbed dose and activity concentration was obtained for the average dependency growth rate of Lemna minor as D = (0.1257) · A0.585. The dose rate of gamma irradiation from 60Co increases with tritium activity dependence, on the specific growth rate of the Lemna minor duckweed. An increase in the tritium activity causes a decrease in the specific growth rate of the Lemna minor duckweed. It indicates that as the quantity of the beta radiation dose increase in Lemna minor duckweed, a higher quantity of gamma radiation will be required to cause the same effect in the specific growth rate of Lemna minor duckweed. The relation between the inhibition of the Lemna minor seedling growth and gamma and beta radiation dosage agrees roughly with that between the decrease of survival rate or fertility and dosage.

Estimation of the Duration of Cooling Time of the SFA of the VVER-1200 Reactor Depending on the Type of Transport Container

As the burnup increases, the requirements of nuclear and radiation safety for spent nuclear fuel (SNF) at the subsequent stages of operation grow. The analysis and estimation of the required cooling time of the spent fuel assemblies (SFAs) of the VVER-1200 reactor for transportation in various types of transport containers (TUK-13 and TUK-141O) are performed. The estimates are based on the analysis of residual energy release and gamma-radiation intensity of SNF depending on the cooling time for different burnups. The data on the absorbed dose rate of neutron and gamma radiation from SNF after 4 and 5 yr of cooling are presented.

Dosimetry and methodology of gamma irradiation for degradation studies on solvent extraction systems

Abstract The recycling of minor actinides from dissolved nuclear fuels by hydrometallurgical separation is one challenging strategy for the management of spent fuel. These future separation processes will likely be based on solvent extraction processes in which an organic solvent system (extractant and diluent) will be contacted with highly radioactive aqueous solutions. To establish a separation between different elements in spent nuclear fuel, many extractants have been studied in the past. A particular example is N,N,N′,N′-tetraoctyl diglycolamide (TODGA), which co-extracts lanthanides and actinides from nitric acid solutions into an organic phase (e.g. TODGA in n-dodecane). The radiolytic stability of these extractants is crucial, since they will absorb high doses of ionizing radiation during their usage. Worldwide, different gamma irradiation facilities are employed to expose extractants to ionizing radiation and gain insight in their radiation stability. The facilities differ in many ways, such as their environment (pool-type or dry), configuration and gamma sources (often 60Co or spent nuclear fuel). In this paper, a dosimetric assessment is made using different dosimeter systems in a pool-type irradiation facility, which has the advantage to be flexible in its arrangement of 60Co sources. It is shown that Red Perspex dosimeters can be used to accurately characterize this high dose rate gamma irradiation field (approx. 13.6 kGy h−1), after comparison with alanine, Fricke and ceric-cerous dosimetry in a lower dose rate gamma irradiation field (approx. 0.5 kGy h−1). A final validation of the whole chain of techniques is obtained by reproduction of the dose constants for TODGA in n-dodecane.

In-situ assessment of background gamma radiation dose levels in outdoor environment of Enugu urban areas, Enugu state, Nigeria

In this study, in-situ measurements of absorbed dose rates of background gamma radiation in 146 outdoor locations within Enugu urban areas were carried out by means of a hand held radiation survey meter equipped with Geiger-Muller tube. In order to assess the radiological health status of the studied environment, annual effective dose (AED) and excess lifetime cancer risk (ELCR) were estimated from the measured dose rates. The measured radiation dose rates across the locations ranged from 77.21 to 180.53 nGy h−1 with a mean value of 124.92 ± 2.00 nGy h−1. The AED and ELCR values ranged from 0.09 to 0.22 mSv y−1 with overall mean of 0.15 mSv y−1 and 0.33 × 10−3 to 0.77 × 10−3 with overall mean of 0.54 × 10−3, respectively. The measured dose rates were significantly higher than world average gamma radiation dose of 59 nGy h−1 for outdoor environment. The dose rates revealed an elevated background radiation levels signifying a radiation contaminated environment. The ELCR values indicate that the accumulation of low-level radiation doses over a lifetime exposure can initiate cancer development in residents of Enugu urban areas.

Sensitivity of Trogoderma graminarium Ev. to the Action of Ionizing Radiation

The effect of different doses and dose rates of gamma radiation on the viability of khapra beetle Trogoderma granarium (larval stage) was studied in laboratory experiments in 2019–2020. The pest-infested grain of spring barley of the Nur variety was irradiated on a GUR-120 unit at dose ranges of 50–450 Gy (dose rate 100, 500, and 950 Gy/h) and 500–1000 Gy (dose rate 950 Gy/h). The irradiation of the khapra beetle at the dose range of 50–450 Gy and at a dose rate of 100 Gy/h caused a total mortality of larvae at doses of 350 and 450 Gy after 7 days, 100 and 300 Gy after 8 days, and 50, 150, 200, 250, and 400 Gy only after 14–17 days. The irradiation of larvae in the same dose range but at a rate of 500 Gy/h led to a more extended mortality rate of the pest population: 8 days at 400 Gy, 12 days at 200 and 300 Gy, 14 days at 350 Gy, and 18 days at doses of 50, 100, 250, and 450 Gy. At 150 Gy, the mortality rate reached 90% on the 14th day and remained at this level for 9 days, which can be explained by different ages of the pest larvae. When the dose rate was increased to 950 Gy/h, the dynamics of the death of khapra beetle larvae demonstrated a long plateau at doses of 350 and 450 Gy at a mortality rate of 70–90%, which caused a delay in their total death up to 20–24 days. The irradiation of the pest in the dose range of 500–1000 Gy at a radiation dose rate of 950 Gy/h proved to be more effective: the total mortality of the larvae was recorded on the fifth to sixth day. Ionizing radiation did not have a significant effect on the content of proteins, fat, fiber, dry matter, and nitrogen-free extractives in barley grain. The ash content statistically significantly changed under the effect of irradiation, but it was, however, no more than 3–6%.

HOLDER DESIGN EVALUATION OF GAMMA AREA MONITOR IN SOLID RADIOACTIVE WASTE INTERM STORAGE ROOM OF RADIOMETALURGY INSTALLATION

HOLDER DESIGN EVALUATION OF GAMMA AREA MONITOR IN SOLID RADIOACTIVE WASTE INTERM STORAGE ROOM OF RADIOMETALURGY INSTALLATION . Radiometalurgy Installation (RMI) is one of Non-Reactor Nuclear Installation where post-irradiation examination (PIE) take place, which give gamma radiation ranged from one µSv/h to the order of mSv/h. The PIE activity produce high-activity radioactive waste as a by-product that stored temporarily in RMI Building. The temporary solid radioactive waste storage room is equipped with in situ gamma area monitor (GAM) as a mean of external radiation protection for radioactive waste operator. This research is conducted to understand the characteristic of GAM Detector and evaluate the positioning of detector, the design of detector holder, and the threshold setting of radiation detection alarm in The temporary solid radioactive waste storage room. The research is conducted by measuring a standard radiation source Cs-137 with the activity of 1 µCi using GAM Detector with variation of position in 4 point, which are in the middle-front of detector, the front-side of the detector vessel, the middle of detector vessel, and back-end of detector vessel, along with variation of source to detector distance, which are 0 cm, 10 cm, 20 cm, 30 cm, 40 cm, and 50 cm. The measurement done in the middle-front of the detector give the highest dose of gamma radiation measured which are 5.63, 4.20, 0.58, 0.28 μSv/h. The result of gamma radiation dose measurement by the detector shows that the closer the source to middle-front part of the detector the higher the radiation measured. The holder design of the gamma radiation detector used in the current GAM device provides information on the gamma radiation dose rate of 74.26% of the actual dose rate. The detector holder currently positioned the middle-front side of the detector upwards therefore the design of detector holder needs to be modified in order for the detector to measure the dose more effectively and give the true number of dose measured

Review of radiation incidents in the territory of the Voronezh region

The aim of the work was to characterize the radiation incidents that took place in the territory of the Voronezh region. Materials and methods. To prepare this article the stock data of the radiological laboratory of the Center for Hygiene and Epidemiology in the Voronezh Region for 2009-2018 was used. All measurements in the investigation of radiation incidents were carried out with the MKS-AT1117M dosimeter-radiometer which passed the state calibration. The equivalent dose rate of gamma radiation (μSv/h) was determined. Results. For the last 10 years, 8 radiation incidents were registered on the territory of the Voronezh region, which were related to domestic clocks - 4 (measurements according to citizens), the detection of orphan sources of ionizing findings - 2, scrap metal - 1 and a thermometer - 1 (during customs inspection). According to the classification of emergencies, the radiation incidents are local, i.e. do not go beyond the territory of the facility, according to the international scale of nuclear and radiological events, INES refer to the incident (anomalies) with the level 1 “minor problems with the safety of components, a radioactive source of low activity level”. All interactions in the investigation of radioactive incidents involving specialists from the radiological laboratory of the Center for Hygiene and Epidemiology in the Voronezh region with other services showed a good level of rapid response.

IDENTIFICATION OF THE FUEL ROD CLADDING DESTRUCTION FROM THE CHANGE OF THE SNF STORAGE CASKS RADIATION

Two options for changing the distribution of spent nuclear fuel due to the possible destruction of the cladding of fuel rods, which causes a change in radiation outside the cask, are considered for VSC-24 casks used for storage of spent nuclear fuel by the dry method. The effect of height reduction due to the destruction of the fuel rods of all 24 SFAs and 10 central SFAs on external radiation is studied analytically and by numerical modeling in the MCNP package. The destruction of 24 SFA is shown to lead to a significant decrease in the dose rate of neutrons and gamma-radiation from 60Co on the weather lid of the cask, and of gamma-radiation from SNF isotopes at the mid-height of the side surface of the cask. The destruction of the ten central SFAs can be determined only from a change in the neutron radiation in the air inlets of the cask.

Distribution of gamma radiation dose rate related with natural radionuclides in all of Vietnam and radiological risk assessment of the built-up environment

A built-up environment utilizes building materials containing natural radionuclides that will change radiological risks. While radiological risks have been estimated from the activity concentrations of natural radionuclides in soil, it is important to evaluate the changes of these risks for the built-up environment using these building materials. Based on the direct measurements of absorbed dose rate in air and calculation of absorbed dose rate in air from activity concentrations in soil for all of Vietnam which has undergone significant economic growth in recent decades, the changes of absorbed dose rate in air and radiological risks before and after construction of many artificial structures were investigated. The results showed that the absorbed dose rates in air were clearly changed by the urbanization, and the difference ratio for all of Vietnam ranged from 0.5 to 2.1, meaning that the artificial structures have been acting as shielding materials to terrestrial gamma-rays or radiation sources. However, changes in annual effective dose in the built-up environment were small, and there was no new radiation risk from the built-up environment for Vietnam.

Microbicidal effectiveness of irradiation from Gamma and X-ray sources at different dose rates against the foodborne illness pathogens Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes in rice

The radiation response of three foodborne illness pathogens was examined for irradiation with cobalt-60 Gamma and low-energy (125 keV) X-ray at different dose rates. Escherichia coli, Salmonella Typhimurium and Listeria monocytogenes were inoculated into rice and irradiated at target doses of 0 (control), 250, 500, 750, 1000, and 1500 Gy with either Gamma radiation (dose rates of 9.1, 3.9 or 0.22 kGy/h) or X-ray radiation (dose rate of 0.76 kGy/h). Doses were measured with traceability to national standards. The dose rate did not significantly affect D10 values (microbicidal effectiveness) for any of the Gamma-irradiated pathogens. Low energy X-ray irradiated pathogens had significantly higher D10 values (lower microbicidal effectiveness) for all pathogens compared to Gamma-irradiated pathogens. The combination of Gamma or X-ray irradiation with a mixture of oregano/thyme essential oil (EO) fumigation generally increased the microbicidal effectiveness compared to irradiation alone. Gamma or low energy X-ray irradiation and plant essential oils such as oregano/thyme, applied alone or in combination, are effective antimicrobial treatments.

Радіаційний захист на залізорудних шахтах в умовах дії техногенно-підсилених джерел природного походження

The Purpose of the Research. To draw up a system of measures for radiation protection at the iron ore mines to facilitate the control of the natural exposure component of miners and to ensure that the established dose criteria are not exceeded. Methodsand Materials. During the development of the measures, the results and conclusions of the radiation-hygienic study of the Kryvyi Rih Agglomeration iron ore mines, the territory of which was identified as radon-dangerous with the presence of man-made sources of natural origin, were used. The measurements were made on the selected network of control points at the horizons of the mines. For analysis, the system was used to measure the volumetric activity of radon and its subsidiary decay products in the mine atmosphere, the dose rate of gamma radiation in mines, the content of natural radionuclides in the ores, the dustiness of the mine atmosphere. At the same time, they were guided by the main regulatory and methodological base. Results and Conclusions.The main stages of the developed system of radiation protection at iron ore mines in terms of technogenic-enhanced sources of natural origin are: radiation-hygienic examination, radiation control, protection measures for normalization of radiation situation, control of the effectiveness of radiation prevention, preventive protection. The decision on the need for radiation monitoring and the implementation of radiation protection measures for iron ore mines is made on the basis of the preliminary survey, which determines the categories of the mine and the type of control. On the basis of the conducted research of iron ore mines of Kryvyi Rih Agglomeration, a system of radiation protection was developed and ordered, the sequence of implementation of measures of radiation examination, radiation control and normalization of radiation situation was substantiated. The measures developed need to be consistent with the recommendations of the International Commission on Radiation Protection regarding radiological protection against radon exposure in the workplace. Key Words: iron ore mines, radiation protection, radiation control, radon, man-made sources of natural origin, miners.

Method for identifying areas of virgin soils using a portable gamma-spectrometer-dosimeter

The dose rate of gamma radiation in air at a height of 1 m above the surface of virgin (undisturbed) soil is the starting point in the basic model that is used to estimate the dose of external radiation to the population living in areas contaminated due to the Chernobyl accident. Today, i.e. more than 30 years after the fallout, the finding of truly virgin lands is a rather difficult task, because many meadows were repeatedly plowed and/or rehabilitated after the accident. The purpose of this study was to develop a quantitative criterion for the detection of virgin soil areas using a portable gamma-ray spectrometer-dosimeter. To achieve this, we have conducted a statistical analysis of published and new data on the use of in situ gamma-ray spectrometry in radioactively contaminated territories of the Bryansk region of Russia and the Gomel region of Belarus in 2015–2018. The sample contains results of decoding 60 gamma spectra recorded at a height of 1 m above the ground in virgin meadows, cultivated lands and forests. Based on the performed analysis, a quantitative dosimetric criterion is proposed for in situ identification of virgin soils using a portable gamma-spectrometer-dosimeter. The article presents an algorithm for searching a virgin plot.

Targeting NRF2, Regulator of Antioxidant System, to Sensitize Glioblastoma Neurosphere Cells to Radiation-Induced Oxidative Stress.

The presence of glioma stem cells (GSCs), which are enriched in neurospheres, may be connected to the radioresistance of glioblastoma (GBM) due to their enhanced antioxidant defense and elevated DNA repair capacity. The aim was to evaluate the responses to different radiation qualities and to reduce radioresistance of U87MG cells, a GBM cell line. U87MG cells were cultured in a 3D model and irradiated with low (24 mGy/h) and high (0.39 Gy/min) dose rates of low LET gamma and high LET carbon ions (1-2 Gy/min). Thereafter, expression of proteins related to oxidative stress response, extracellular 8-oxo-dG, and neurospheres were determined. LD50 for carbon ions was significantly lower compared to LD50 of high and low dose rate gamma radiation. A significantly higher level of 8-oxo-dG was detected in the media of cells exposed to a low dose rate as compared to a high dose rate of gamma or carbon ions. A downregulation of oxidative stress proteins was also observed (NRF2, hMTH1, and SOD1). The NRF2 gene was knocked down by CRISPR/Cas9 in neurosphere cells, resulting in less self-renewal, more differentiated cells, and less proliferation capacity after irradiation with low and high dose rate gamma rays. Overall, U87MG glioma neurospheres presented differential responses to distinct radiation qualities and NRF2 plays an important role in cellular sensitivity to radiation.

The effect of high dose rate gamma irradiation on the curing of CaO-FexOy-SiO2 slag based inorganic polymers: Mechanical and microstructural analysis

In search for alternative cementitious materials for radioactive waste encapsulation, geopolymers and inorganic polymers (IPs) have received wide attention. Moreover, Fe-rich IPs offer an interesting alternative to high density concretes for use in radiation shielding applications. Materials can however be altered when subjected to ionizing radiation, creating the necessity to evaluate the material’s behaviour under irradiation conditions. In this study the effect of high dose rate (8.85 kGy/h) gamma irradiation is investigated on CaO-FexOy-SiO2 slag-based IPs. Samples with different curing times (1 h, 24 h and 28 days) prior to the irradiation were irradiated to a dose of 200 kGy using a60Co source.The effect of gamma radiation is observed to be highly dependent on the curing time prior to irradiation. 28 days cured samples are found to be resistant to the irradiation for the dose (rate) and properties tested without any significant change in strength, indentation characteristics, porosity and Fe3+ content. The IPs studied show a different behaviour when irradiated immediately after casting or after 24 h of curing. It is therefore thought that the mechanism behind the effect of irradiation is different for the non-hardened samples compared to hardened samples. For the 1 h cured samples prior to irradiation multiple effects were observed: an increase of the compressive strength by a factor 2.20, a decrease in hardness of the binder by a factor of 0.73, a lower Young’s-modulus of the binder by a factor of 0.67, a decrease of creep in time for the binder by a factor of 0.72, a decrease in porosity by a factor of 0.92 and an increase of the Fe3+/ΣFe ratio by a factor of 1.95.

Analytical description of the hydrogen evolution from concrete under the effect of gamma radiation

The formation of explosive gas mixtures due to the evolution of hydrogen from concrete structures for radiation protection of nuclear power buildings should be taken into account when designing and operating them. However, this requires methods for estimating and predicting the radiation evolution of hydrogen.This paper was done due to the lack of analytical methods for determining the gas evolution from concrete and their components under the influence of gamma radiation. In the work, based on the available experimental data, the model was selected, checked, and adjusted for an analytical description of the process of hydrogen evolution from concrete on aggregates that do not contain water under the influence of gamma radiation.When selecting the model, it was assumed that the evolution of hydrogen from concrete on aggregates that do not contain water under the effect of gamma radiation is mainly due to the radiation decomposition of evaporable water (free water and adsorbed water) from hardened cement paste (cement stone) and is determined by the amount of evaporable water in the material and the power of the absorbed dose of gamma radiation. It was taken into account that the amount of evaporable water during irradiation decreases with increasing time and temperature of irradiation.Verification of the possibility of using the selected model, its necessary adjustment and determination of the main parameters of this model was performed on the basis of available experimental data on the evolution of hydrogen from Portland cement stone under the influence of gamma radiation. We used experimental data on the release of hydrogen and water from cement stone containing and practically not containing evaporable water when irradiated with gamma rays with an average energy of 1.25 MeV at the absorbed dose rate of 0.87 kGy/h, 3.84 kGy/h and 7.05 kGy/h at temperatures of 25, 40 and 60 °C for up to 2 months. The dependence of the model parameters on the absorbed dose rate of gamma radiation and the irradiation temperature is shown. For cement stone dried at 120 °C to remove evaporable water, the amount of residual evaporable water (residual evaporable water or decomposed chemically bound water) was studied and determined.

The Influence of Natural Sources on Radiation Exposure Levels in the Population of the Arkhangelsk Region

Introduction: The issue of radiation safety in terms of population exposure to natural sources of background radiation remains relevant since, according to the results of numerous studies, among all sources of ionizing radiation the natural ones contribute the most to the population exposure worldwide. Our purpose was to assess the contribution of natural sources of background radiation to the individual effective dose of the population of the Arkhangelsk Region. Materials and methods: We measured residential indoor and outdoor gamma dose rates and the residential indoor equivalent equilibrium volumetric activity of radon isotopes. We also analyzed data of statistical form No. 4-DOZ “Information about population exposure doses attributed to the natural and anthropogenically altered background radiation” and radiation hygiene passportization conducted in 2008–2017 by cities and districts of the Arkhangelsk Region and estimated long-term average indicators of the individual effective dose of radiation and chain indicators of the growth rate. Results: We established that the internal exposure to radon isotopes (46.8%) and external terrigenous exposure (23.6%) contributed the most to the individual effective dose due to natural sources in the population of the Arkhangelsk Region. In 2008–2017, the individual effective dose attributed to natural sources was 2.50 mSv/yr, to external exposure – 0.59 mSv/yr, and to internal exposure to radon isotopes – 1.17 mSv/yr. The analysis of average values of the equivalent equilibrium volumetric activity of radon isotopes and the gamma radiation dose rate in residential buildings of various type (wooden, single-story stone and multistory stone) in the Arkhangelsk Region supported the conclusion about the significant contribution of the former to the individual effective dose due to natural sources. Conclusions: We established the contribution of natural sources of ionizing radiation to the total doses of the population.