Study of the Influence of Forest and Peat Fires on the Radiation Situation in the South-Western Regions of the Bryansk Region

Abstract

   Introduction. The paper considers the influence of radiation forest and peat fires on the spread of radioactive contamination, which affects the well-being of thousands of people. The state of the environment in vast territories is deteriorating; negative socio-economic processes are developing. This is a serious problem of two states: the Russian Federation and the Republic of Belarus.   The objectives of the presented work are to study the radiation situation in forests and peat bogs located in the border areas of the Bryansk region, as well as to study the possibility of transferring radioactive materials during forest and peat fires.   Materials and Methods. The facts that clarified the theoretical basis of the presented research are highlighted in the scientific literature. The authors took into account, in particular, that: – the activity of radionuclides in the soil decreases in direct proportion to the depth; – a peat fire is an uncontrolled burning; – emissions of caesium-137 fractions (137Cs) during a fire can reach 3–4 %. We know the areas of forests in radiation-contaminated territories (RCT) of the Bryansk region from the applied literature and official sources. The most problematic areas from this point of view have been identified.A mobile radiometric laboratory, a scintillation gamma-ray spectrometer MKS-AT6101S were involved in the expedition research. The results of field gamma-ray spectrometry were recorded in three localities. The calculations for a hypothetical fire were carried out using the SAUR AIUS RSCHS 2030 software tool.   Results. The consequences of large and prolonged fires in the exclusion zone of the Chernobyl nuclear power plant are analyzed. It is established that the incidents did not lead to dangerous consequences for the population. The total effective dose of inhalations was ~0.003 % of the permissible level of irradiation. It is noted, however, that the forest soil of the Bryansk region has received significant damage from 137Cs pollution. The density of such pollution exceeded 5 Ci/km2 in 40 % of the affected forests. Of these, an indicator of 15-40 Ci/km2 and more was recorded in 16 %, in some quarters — up to 200 Ci/km2. It is established that zones with a high contamination density (40 Ci/km2) will remain in the region until 2026. Five districts are particularly problematic: Gordeevsky, Zlynkovsky, Klintsovsky, Krasnogorsky and Novozybkovsky. When fixing and predicting harm, the authors of the presented work proceeded from the following fact: during fires, the combustion products (forest litter, grass and undergrowth) contain more radioactive substances than the crowns of trees. In this regard, measurements were not made at a significant height. The field study route was chosen based on the available data on the maximum level of radioactive contamination. The ambient dose equivalent rate (ADER) of gamma radiation recorded at 2,757 points did not exceed 1.2 μSv/h (with an average value of 0.2-0.3 μSv/h). Measurements in the marshes did not reveal traces of 137Cs at a depth of more than 40 cm. The maximum activity of 137Cs was observed in the upper (0–4 cm) soil layer (up to 65 %). Taking into account the data obtained, the possibility of radioactive containation in the event of a forest fire was assessed. According to the calculations in the software environment, radioactive contamination will spread to 348 hectares. The density of radioactive contamination of the area may increase by 5–10 % (from the initial one). 33 people will suffer; there is a threat of death of 1 person. It has been established that a burning peat bog is the most powerful and long-term source of radioactive contamination, therefore it is important to prevent peat and forest fires. This will reduce the transfer of radionuclides and emissions of radioactive fumes. Remote and surface radiation monitoring facilities should be developed.   Discussion and Conclusion. The registered ADER is not dangerous for the health of the population of the Bryansk region. However, frequent fires significantly increase the likelihood of transferring active 137Cs to residential areas. In this sense, timely monitoring and forecasting of fires is relevant. The authors formulated proposals to improve the technical and technological components of the solution of the considered problem.   1. To clarify the radiation situation, all-terrain vehicles should be equipped with: – means of registering the radiation situation; – software and hardware complex for automatic collection, analysis of information and its fixation in databases.   2. There should be a reliable cellular communication between all rapid response units in the emergency zone.   Further research is focused on the creation of fast-deployable radiation monitoring modules and mobile aerial photography complexes using drones in the emergency zone.