In connection with the planned prolonged discharge of tritium-containing water from the Fukushima Daiichi Nuclear Power Plant, a gradual increase in tritium concentrations is expected in the coastal waters of the Far Eastern regions of the Russian Federation.

The aim of this study is to improve the methods for ensuring the radiation safety of the population under conditions of long-term discharge of radioactive water from the Fukushima Daiichi Nuclear Power Plant based on numerical modeling of ocean current circulation.

Materials and Methods: Seawater samples from the coastal areas of Kamchatka, Primorsky, and Khabarovsk Krais, Magadan and Sakhalin Oblasts, and the Chukotka Autonomous Okrug for the period 2023–2025 were used for the analysis of tritium content. Lagrangian models accounting for the spatiotemporal structure of oceanic circulation and currents were employed to describe tritium transport processes.

Results and Discussion: The mean values of tritium specific activity in samples collected at distances of up to 1000 m from the shore were shown to range from less than 1.0 Bq/kg to 5.5 Bq/kg. Numerical modeling revealed potential accumulation zones for tritium discharged with treated water from the Fukushima Daiichi Nuclear Power Plant: the Southern Kuril Islands, Sakhalin Island, the southern tip of the Kamchatka Peninsula, and Bering Island. The East Kamchatka Current forms a dynamic barrier along the eastern coast of Kamchatka, limiting the intrusion of contaminated waters into coastal areas.

Conclusion: To organize effective long-term monitoring of tritium in seawater and, subsequently, in seafood, it is necessary to refine the areas of the most likely tritium accumulation in the waters of the Russian Far East.

Monitoring internal doses from plutonium is most effectively accomplished by an indirect method based on the interpretation of nuclide activity measurements in excreta using biokinetic and dosimetric models. Currently, Russian Federation regulatory documents utilize the models presented by the International Commission on Radiological Protection in Publications 30, 66, and 67, while the International Commission on Radiological Protection has developed new models and approaches presented in Publications 130, 134, 137, and 141.

The aim of this study was to demonstrate the actual dynamics of plutonium excretion in urine and feces in comparison with calculated data upon the intake of plutonium as part of an industrial compound of complex isotopic composition.

Materials and Methods: The initial data for the study were the results of determining the activity of plutonium in daily amounts of urine and feces of three workers with acute inhalation intake of industrial plutonium compounds as a result of an emergency.

Results and Discussion: For each case, the most suitable scenario (model and set of physicochemical properties of the compound) was selected using the Akaike criterion, depending on the initial data used for the calculation. The calculations were performed based on the results of plutonium activity measurements in urine, the results of plutonium activity measurements in feces, and the results of plutonium activity measurements in urine and feces simultaneously. The statistical analysis performed showed that the choice of the most suitable model and set of physicochemical properties of the compound was determined by the choice of initial data. In one case, none of the models adequately explained the observed levels of plutonium in urine and feces.

Conclusion: There is undoubtedly a current lack of knowledge regarding the metabolism of industrial plutonium compounds, including those present at new fuel production sites. This requires extensive research into both the biokinetics and physicochemical properties of industrial plutonium compounds.

The development strategy for Russia's shipbuilding industry anticipates a multi-fold increase in the capacity of ship repair enterprises servicing nuclear maritime facilities, which underscores the need to enhance radiation safety for personnel.

The aim of the study was to determine the conditions and levels of occupational radiation exposure at the workplaces of various personnel categories at a nuclear ship repair enterprise, including under increased production loads.

Materials and methods: The study was conducted at a major nuclear ship repair facility. The ambient dose equivalent rate of gamma radiation and beta contamination levels were measured at workplaces of main, auxiliary, and administrative personnel (Group A). Data from the plant's radiation monitoring and five-year statistical reports on individual doses (Form No. 1-DOZ, 2016– 2020) were analyzed. Individual thermoluminescent dosimeters were used to estimate potential maximum doses.

Results and discussion: During periods when no radiation-hazardous work was being performed, the ambient dose equivalent rate at most workplaces did not exceed background levels (0,16 μSv/h), except near a tank with liquid radioactive waste (up to 6,75 μSv/h). During potentially hazardous operations (primary circuit maintenance, dismantling of safety mechanisms), the ambient dose equivalent rate reached 4,91– 7,15 μSv/h. The highest five-year average individual effective doses were recorded for flaw detection inspectors (6,89 mSv/year). Calculations for a hypothetical scenario of full workload revealed a potential risk of exceeding dose limits for certain occupations (fitter-installer, flaw detection inspector), especially for the lens of the eye.

Conclusion: Radiation exposure conditions for personnel vary significantly depending on profession and type of work. To ensure radiation safety, a differentiated approach to planning repair work is required, taking into account personnel specialty, the nature of operations, and strict adherence to safety protocols, especially during high-load periods and for high-risk groups.

The aim of the study was to perform phantom dosimetry of organs and tissues to assess effective radiation doses to patients during computed tomography of combined areas of the body and calculated based on the readings on the scanner console.

Materials and Methods: The study was performed on СT-scanner Toshiba Aquilion 64 an anthropomorphic tissue-equivalent phantom weighing 73.5 kg using thermoluminescent detectors located in the locations of organs and tissues, under standard computed tomography protocols of two combined body regions: 1 – organs of thorax, abdomen and pelvis; 2 – organs of abdomen and pelvis. The effective radiation dose was calculated using tissue weighting factors according to NRB-99/2009 and ICRP Publication 103 recommendations.

Results and Discussion: The largest contribution to the total radiation dose was found for the gonads, red bone marrow, colon, lungs and stomach (71.8-76.2% in total). It was established that the effective radiation doses to patients during computed tomography, calculated based on the results of phantom dosimetry with TLD detectors, are higher than the values obtained from DLP data on the console of a computer scanner using tissue weighting factors according to ICRP Publication 103 for CT-1 by 1.12 times, for CT-2 by 1.13 times, according to NRB-99/2009 for CT-1 by 1.30 times, for CT-2 by 1.38 times.

Conclusion: Dosimetry on an anthropomorphic tissue-equivalent phantom demonstrates higher patient radiation doses during computed tomography compared to dose values calculated by DLP on the computed tomography scanner console. This demonstrates the importance of periodically comparing patient doses calculated by DLP on the computed tomography scanner console with doses recorded by direct dosimetry under real computed tomography scanning conditions in radiology departments and centers.

Form №3-DOZ is commonly used to analyze patient doses from radiographic procedures. However, direct comparison of average effective dose data from Form №3-DOZ with results of experimental studies is inappropriate, as Form №3-DOZ presents effective doses averaged over the patient's exposure projections. This leads to significant overor underestimation of the comparison results.

The aim of this study was to develop a method for estimating average effective doses per frontal or lateral projection for common radiographic procedures using Form №3-DOZ data.

Materials and Methods: The study was based on the data from the regional databanks of Form № 3-DOZ for Saint Petersburg and Leningrad regions; an original method for calculating average effective doses per projection has been developed.

Results and Discussion: average effective doses for the most common X-ray procedures performed on digital and analog X-ray units in St. Petersburg and the Leningrad Region in 2023 were determined.

Conclusion: It is advisable to integrate this method into software for completing Form №3-DOZ.

The relevance of the research of new radioprotectors is due to the need to protect healthy tissues during radiation therapy. Existing drugs have serious side effects, which requires the search for safer and more effective analogues.

The aim of the work is a comparative analysis of the radioprotective efficacy of three promising compounds – fumaric acid, 3-hydroxypyridine fumarate and deanol aceglumate in vitro. Tasks: to determine non-toxic concentrations of compounds, to evaluate their protective effect under different types of radiation (gamma quanta, protons, ¹²C ions), to compare the effect on normal (fibroblasts Fb-hTERT) and tumor (neuroblastoma SK-N-BE(2)) cells.

Materials and Methods: the study was conducted on cultures of cells under the influence of ionizing radiation of different quality: gamma quanta (60Co), protons and accelerated ¹²C ions. Optimal concentrations have been established: fumaric acid – 400 μmol, 3-hydroxypyridine fumarate – 200 μmol, deanol aceglumate – 1000 μmol. Incubation time is 24 hours.

Results and Discussion: It was shown that all compounds showed a significant radioprotective effect on gamma radiation (1-12 Gy) for fibroblasts; the protective effect was also observed on tumor cells. There was no radioprotective effect when irradiated with protons and ¹²C ions. Deanol aceglumate has demonstrated the greatest effectiveness.

Conclusion: The study confirmed the prospects of deanol aceglumate and other compounds as radioprotectors under gamma irradiation. Their use can reduce damage to healthy tissues during radiation therapy. However, no protective effect has been detected for protons and heavy ions, which requires further study.

The relevance of this study lies in the need to reconsider established approaches to the use of personal protective equipment in computed tomography due to the widespread implementation of automatic tube current and voltage modulation algorithms. Since PPE can distort the input data for these algorithms, their use may not only fail to reduce but could also unjustifiably increase the patient's radiation dose, which requires detailed experimental verification, especially in pediatric practice where patients are most sensitive to ionizing radiation.

The aim of this work is to assess the influence of personal protective equipment on the performance of the automatic tube current and voltage modulation programs (CareDose 4D and Care kV) during CT examinations on a Somatom Force (Siemens) scanner, using an anthropomorphic phantom of a five-year-old child.

Materials and Methods: The study was conducted at the CT department of the Almazov National Medical Research Centre using an anthropomorphic phantom of a five-year-old child and a technically sound Somatom Force (Siemens) tomograph. To assess the impact of personal protective equipment on the operation of the automatic current and voltage modulation programs (CareDose 4D and Care kV), a series of phantom scans was performed with and without various positioning options for a protective lead apron, simulating real clinical practice.

Results and Discussion: The results showed that when a lead apron enters the topogram area, the system interprets this as an increase in the patient's body size and density, which automatically increases the radiation parameters compared to a scan performed without the lead apron.

Conclusion: Evaluating the impact of this effect on absorbed and effective doses requires further research to determine the appropriateness of using personal protective equipment in computed tomography.

To date, studies of the effects of parental pre-conceptional radiation exposure on the health of offspring have not provided sufficient evidence to confirm the detected harm. This underscores the importance of ongoing research in this area.

The objective of the study is to analyze the risk of solid cancer incidence in the Urals Cohort of Exposed Population Offspring for the period from 1956 to 2020.

Materials and methods: the number of the analyzed cohort amounted to 24952 people, the average age by the end of the follow-up period was 40 years. During the 65-year period, 569 solid cancers were registered. The dose to the parents' gonads was calculated based on the TRDS2016 dosimetry system developed by the staff of the Southern Urals Federal Research and Clinical Center for Medical Biophysics. The median dose to the ovaries of mothers of the cohort members was 6.1 mGy, to the testes of fathers 4.5 mGy, total parental gonadal dose 31.2 mGy. Regression analysis with Poisson distribution using EPICURE statistical package programs was applied for risk assessment.

Results: risk analysis of all solid cancer incidence among the offspring of exposed parents did not reveal a significant dependence on parental gonadal dose. At the same time, a significant dependence of the lung cancer risk on maternal and total parental gonadal doses was found among cohort members. The results are in good agreement with similar mortality data in the same cohort. The point values of lung cancer risk have a wide confidence interval, indicating that uncertainty exists and requires further investigation.

The relevance of the work is due to the need to improve the methods of control of professional internal exposure due to incorporated radionuclides with a long biological half-life.

The aim of the work was to test a methodical document regulating the organization of internal exposure control due to plutonium based on a risk-based approach to limiting radiation exposure to personnel. The task of the work was a practical application of the method of interpretation of the results of individual dosimetric control in monitoring the annual increment of the lifetime excess risk of death from radiation-induced cancer.

Materials and Methods: The control system is based on the principle of limiting the doses of radiation to plutonium storage organs, depending on the age at which the exposure occurred, and the permissible levels of plutonium exposure make it possible not to exceed the acceptable level of the radiation-related risk throughout the work experience. Based on an array of data from individual dosimetric monitoring of 44 employees of the Mayak production association, calculations of annual equivalent doses to critical organs were performed, and the radiation effect on personnel was estimated based on the expected effective dose.

Results and Discussion: In most cases, during the control periods, admissions were recorded that led to the formation of internal radiation doses above the registration level. The registered values of the expected effective doses for fifty years, as well as the values of equivalent doses for critical organs, did not exceed the established limits. In seven cases, the equivalent doses to critical organs were higher than 60 mSv, while the annual excess risk for the year of control did not exceed 1 ×10 ^-3. For all employees of the controlled group, no excess of the acceptable annual risk was recorded in any of the control periods.

Conclusion: The completed test operation of the methodological guidelines showed the practical applicability of the methods described in the document, made it possible to identify the shortcomings of the tested approach and formulate proposals for improving the calculation algorithms.

The work is devoted to the study of the possibility of predicting the gamma dose rate from ¹³⁷Cs +¹³⁷mBa radionuclides that fell into the environment as a result of a large-scale radiation accident. Based on existing analytical models of cesium migration on the one hand and natural data on the vertical distribution of cesium in the soils of areas contaminated as a result of the Chernobyl accident on the other, a forecast of the dose rate of gamma radiation in the air over open areas was constructed. The experimental database contained 180 profiles from the Bryansk region of the Russian Federation and about 100 profiles, including global ones, from Bavaria (Germany). To approximate the radionuclide distribution in the soil, solutions of the convectivediffusion equation and the lognormal distribution were used. The best fit to the real distributions of the radionuclide in the soil was the χ² distribution, which is a solution of the convective-diffusion equation with an increasing diffusion coefficient, and the lognormal distribution. For both distributions, the dependences of the parameters (diffusion penetration rate and movement rate with soil moisture) on time were found. Assuming the universality of these dependences, a method for their reconstruction in time is proposed, for example, based on once selected profiles of global fallouts. The absorbed dose rate values in the air were calculated for up to 50 years after the fallout. The average difference between the experimental data, expressed as the ratio of the dose rate in the air at a height of 1 m above the soil from the profile of ¹³⁷Cs + ¹³⁴Cs radionuclides at time t to the dose rate in the air for radionuclides located on the soil surface from the calculated ones, was 9 % for the Bryansk region and 14 % for Bavaria. The calculated values of the absorbed dose rate in the air were verified using the results of its measurements in the Bryansk region in the period of 3–24 years after the fallout. They coincided with the measured values within 95 % of the measurement error interval throughout the entire measurement time period except for the 8th year after the accident, which confirms the adequacy of the radionuclide distributions in the soil used in the work.

The Mayak Production Association is an enterprise of the Rosatom State Corporation, characterized by the highest tritium emissions, which exceed the total emissions from all other nuclear industry and nuclear power enterprises in the Russian Federation. Consequently, the population of Ozyorsk, residing in close proximity to the Mayak Production Association, has been and continues to be exposed to internal irradiation from tritium over a prolonged period.

The aim of this study is to investigate the factors affecting the volumetric activity of tritium in urine samples from residents of Ozyorsk, a city located in the area influenced by the Mayak Production Association, to estimate the committed effective dose equivalent of internal exposure from tritium.

Materials and Methods: Urine samples were collected from Ozyorsk residents in 2016, 2017, 2018, 2021, and 2023. A total of 218 samples were collected, including 58 samples from children. The volumetric activity of tritium in urine was measured using a Quantulus-1220 device. To collect data on factors influencing tritium levels in residents’ urine, a questionnaire survey was conducted. Statistical analysis was performed using Microsoft Excel and R software.

Results and Discussion: The volumetric activity levels of tritium in the urine of Ozyorsk residents ranged from 4 to 49 Bq/L. A multivariate regression model was developed to describe the influence of various factors on the volumetric activity of tritium in residents’ urine under combined pathways of tritium intake. Estimates of the expected effective doses for Ozyorsk residents were less than 0.076 % of the dose limit of 1 mSv.

Conclusion: Investigating the key factors affecting the volumetric activity of tritium in residents’ urine allows not only to assess actual internal exposure doses but also to predict the doses in the event of increased tritium emissions from enterprises of the Rosatom State Corporation. Additionally, it facilitates the development of approaches for retrospective dose assessment in the population.

Annual assessment of population exposure levels and dose structure is required to identify priority exposure situations and to substantiate radiation risk management measures at the level of a constituent entity of the Russian Federation.

Aim of the study: to provide a comparative hygienic assessment of exposure levels and dose structure for the populations of Saint Petersburg and Leningrad Oblast in 2014–2023 and to compare associated health risks.

Materials and Methods: radiation-hygienic passports of Saint Petersburg and Leningrad Oblast for 2014–2023 were analyzed, together with data from the Federal repository of radiationhygienic passports, the compilations Doses of Radiation Exposure of the Population of the Russian Federation, and the reference series Radiation Situation in the Territory of the Russian Federation; mean individual lifetime radiation risk indices were calculated in accordance with MR 2.6.1.0145-19.

Results and Discussion: over the study period, the average individual annual effective dose from all sources was 3.8–5.2 mSv in Saint Petersburg and 3.2–4.2 mSv in Leningrad Oblast. In 2023, contributions from natural sources reached 72 % and 89 %, respectively; medical exposure accounted for 27 % and 11 %, while other sources contributed less than 1 %. In 2014–2023, medical exposure doses increased (growth rates of 246.6 % in Saint Petersburg and 232.0 % in Leningrad Oblast), with computed tomography providing the main contribution to the collective dose. Radon exposure made the largest contribution to the mean individual lifetime radiation risk in both regions; the risk attributable to medical exposure was higher in Saint Petersburg than in Leningrad Oblast (maximum 8.7 × 10⁻⁵ in 2023 versus 3.4 × 10⁻⁵ in Leningrad Oblast). Technogenic exposure of the population in contaminated areas and within surveillance zones of radiation facilities remained low (≤ 0.1 mSv and ≤ 0.006 mSv).

Conclusion: The findings obtained refine regional prevention priorities, including develpment and implementation of regional radon programs as well as justification and optimization of X-ray examinations.

Despite the sufficient scientific justification and certain successes achieved by Rospotrebnadzor in ensuring the radiation safety of the population when exposed to natural radiation sources, there are currently a number of unresolved issues that prevent the full application of existing sanitary and epidemiological requirements regarding natural radiation in practice. Summary: The paper presents an overview of the main practical issues faced by Rospotrebnadzor specialists in the course of ensuring radiation safety of the population related to natural sources of exposure, analyzes the causes and consequences of their occurrence, and evaluates the prospects for their solution. It is shown that the main practical issues in implementing current sanitary and epidemiological requirements, and the functioning of the system for collecting, recording and analyzing data on the levels of all major natural sources of public exposure, are: reduction in the number of radiation surveys conducted and measurements taken in existing buildings; unavailability of certain supplies for radon measurements; lack of practical tools for monitoring commodities with elevated concentration of natural radionuclides; lack of a clear procedure for implementing measures aimed at reducing public exposure to natural sources; reduction in the number of private testing laboratories transmitting data to Regional databank of radiation doses to the public; and the lack of practical tools holding the laboratories accountable for the poor quality of surveys conducted and measurements taken. The solution to the described issues may be: the adoption of radon programs; the resumption of the practice of issuing sanitary and epidemiological certificates for commodities or the inclusion of certain types of commodities in the list of products (goods) subject to state registration; the development of interdepartmental documents defining the procedure for handling of non-compliance with sanitary requirements; the development of a legal mechanism for interaction between Rospotrebnadzor and Rosaccreditation on the work of testing laboratories and the application of radiation control methods. Conclusion: Solving practical issues of ensuring public radiation safety related to exposure to natural sources is impossible without the coordinated work of federal and regional executive authorities, including clear mechanisms for interaction, planning and implementation of radon mitigation actions.

The gamma dose rate in air at any given outdoor location is not constant throughout the year. These fluctuations of the dose rate should be taking into account when assessing external radiation dose to humans. The aim of this study was to determine the seasonal variability of ambient dose equivalent rate on the streets of St. Petersburg. Materials and Methods: A portable gamma spectrometer-dosimeter, carried in a backpack on the operator, was used to measure gamma spectra in situ. Measurements were conducted in summer and winter on the streets located in the central part of the city. For comparison, spectra were measured on paths and lawns of the city parks. Results and Discussion: On average, ambient dose equivalent rates from natural radionuclides on the streets in winter were 6 % lower than those in summer. The difference was statistically significant (Wilcoxon test for the pair samples, p < 0.01). More pronounced differences between winter and summer were found in parks: with a snow cover depth of approximately 20 cm, the ambient dose equivalent rate on lawns and paths decreased by 32 % and 29 %, respectively. The differences between the seasons were statistically significant (p < 0.05). The relatively small decrease in the ambient dose equivalent rate on the city streets in winter is explained not only by snow removal from sidewalks and roadways but also by the fact that in this location some gamma radiation comes from radionuclides in the walls of buildings. Conclusion: The seasonal variations in the ambient dose equivalent rate from natural radionuclides on the city streets are extremely small. A coefficient of 0.95 can be used to estimate the magnitude of the reduction in the corresponding rate of external exposure to humans on the streets in winter compared to summer.