[en] Methodology and results are presented for the “safety ranking” of legacy radioactive material storage sites that are situated in populated areas adjacent to the Chernobyl Exclusion Zone and contain wastes from clean-up and decontamination operations carried out in 1986 - 1989. Based on this safety ranking, recommendations regarding the order of remediation and management strategy for these sites are provided. The results suggest that remedial works for radioactive legacy sites can be optimized, and waste volumes that may require retrieval and further disposal in engineered facilities can be considerably minimized. It is recommended that the managing organization (Kyiv Inter-Regional Special Combine of UkrSC “Radon”) should focus their characterization, monitoring and maintenance works on the relatively few higher risk legacy sites identified in this study, while low-risk sites can be eventually released from regulatory control.

[en] Averaged assessments of radiological effectiveness dynamics of mineral fertilizers of long-term application at the late phase of ChNPP accident have been carried out on the base of 3-5-years experiments. The influence of mineral fertilizers, used in different doses for agricultural plants, has been shown for intensity of ¹³⁷Cs accumulation by plants on various soil-climatic conditions of radioactively contaminated territory of the Ukraine. (authors)

[en] Analysis of the results of the selective monitoring of ¹³⁷Cs in cow milk in settlements, where values of the milk contamination have not met requirements of the permissible levels since the Chernobyl accident, was performed. Monitoring network, which was created at the institute, is covering the most critical settlements of Zhytomyr, Rivne and Volyn regions. The article presents data on radionuclide contamination of cow milk for the last 5 years (2011 - 2015), while observations are carried out since the 90s of the last century. Long-term data show that the current dynamics of contamination of cow milk in these settlements is comparable to the decrease of ¹³⁷Cs activity due to its physical decay. (authors)

[en] Using the calculated values for wood samples (relative diameter, height and relative activity concentration of ¹³⁷Cs) se-lected in different parts of the profile tree stems, statistical and graphical interpretation of the regularity of the distribution of ¹³⁷Cs in the wood of model trees of Scots pine were performed. In the research detected observation uniformity of sam-ples in the studied profiles stems for the relative activity concentration of ¹³⁷Cs, calculated on the base of the ratio of the activity concentration of tree rings for certain years to their median at height of 1.3 m. Three intervals of the relative di-ameters for stem wood of model trees at height of 1.3 m of the study stand were obtained, that is characterized by signifi-cant difference on the activity concentration of ¹³⁷Cs: d(ω)_1,3m ≤ 0,55 (Am(ω) = 0,63 ± 0,08), 0,55 < d(ω)_1,3m ≤ 0,95 (Am(ω) = 1,01 ± 0,04), 0,95 < d(ω)_1,3m ≤ 1,0 (Am(ω) = 2,1 ± 0,5). (authors)

[en] ⁹⁰Sr and ¹³⁷Сs content in soil and unplanted wood of small size has been measured along the southern fuel trace of Chernobyl fallout, in Ivankov region of Kiev Oblast during 2012 - 2013. At present, due to biogenic and vertical ⁹⁰Sr migration in soil of forests, is reserved in 20-cm rooting-layer, containing less than 0.25 mg-eq of exchangeable calcium per 100 g of soil, reduced by 67 ± 18 % in average. Therefore, contamination of fuel wood with ⁹⁰Sr today is depended weakly on exchangeable calcium content in soil (up to 1 mg-eq/100 g), considering the equal levels of the initial soil contamination with ⁹⁰Sr. Values of ⁹⁰Sr transfer factor (TF) to unplanted wood of deciduous trees and pine mounted to 34 ± 20 and 61 ± 56 (Bq/kg/(kBq/m²), in average, that is in dozens exceeded the values, recommended by IAEA. In practice, at total area of Ivankov region there exist a risk to overrun hygienic norm value of ⁹⁰Sr content in fuel wood, and brushwood. (authors)

[en] A probabilistic approach on description of radionuclide contamination of agricultural land as well as crops grown on the land was suggested. The approach can be used to substantiate the possibility to make available the land for agricultural use. The approach allows to assess not only the average value of the activity concentration of radionuclides in crop, but also the probability of exceeding permissible levels. Method was successfully tested in the fields, which are allocated to the second zone of radioactive contamination. These fields are located in Narodichy district of Zhytomyr region and Polisskyi district of Kyiv region. (authors)

[en] Uniqueness of radioecological situation in Ukraine is due to the presence of large areas of peat soils spread, which observed abnormally high rates of radioactive cesium plants. Even in 30 years after the Chernobyl accident on peat soils with levels of contamination by ¹³⁷Cs about 37 kBk/m² agricultural products exceeding the requirements of AS-06. Developed and tested traditional anti radiation measures are not received due to circumstances, state support for the contaminated area. Therefore, we proposed different approaches to improve the radioecological situation on the contaminated peat soils.). (authors)

[en] Results of the small-field experimental study of the dynamics of biological availability of freshly added standard radioactive solution of ¹³⁷Cs in peat-bog soil are presented. The initial values of the ¹³⁷Cs concentration ratios CR(t) and transfer factors TF(t), in the aboveground phytomass of natural meadow grass vegetation in peat-bog soils in the real soil-climatic conditions of Western Polissya were determined. Based on the results of the field and laboratory studies, the values of fast and slow periods of the ecological half-reduction ( T_e^f and T_e^s , respectively) of CR and TF of radioactive cesium in the studied soils were estimated. The model for prediction of the dynamics of CR and TF of radioactive cesium into natural meadow grass vegetation from peat-bog soils with its abnormal high biological availability was proposed. (authors)

[en] An experiment to search for 2β processes in ¹⁰⁶Cd with the help of ¹⁰⁶CdWO₄ crystal scintillator (mass of 215 g), enriched in ¹⁰⁶Cd up to 66 %, is in progress at the Gran Sasso National Laboratories of the INFN (Italy). After 1320 h of data taking, limits on double beta processes in ¹⁰⁶Cd have been established on the level of 10¹⁹ - 10²⁰ yr, in particular (all the results at 90 % C.L.): T_1/2(0ν2ε) > 3.6 x 10²⁰ yr, T_1/2(2νεβ⁺) > 7.2 x 10¹⁹ yr, and T_1/2(2ν2β⁺) > 2.5 x 10²⁰ yr. Resonant 0ν2ε processes have been restricted as T_1/2(0ν2K) > 1.4 x 10²⁰ yr and T_1/2(0νLK) > 3.2 x 10²⁰ yr. A possible resonant enhancement of the 0ν2ε processes is estimated in the framework of the QRPA approach.

[en] Method of calculation of nuclear transformations in irradiated targets is realized for selection of optimal conditions for accumulation of radioisotopes in reactor, taking into account contributions of different energy neutrons (thermal, resonance and fast). Wide potentialities of program complex MCNP-4C based on the method of statistical testing (Monte Carlo method) were used. Positive in proposed method is that all calculations starting from spectra and fluxes of neutrons in reactor and completing by quantity of accumulating nuclei carry out within the framework of the same methodological approach. It was shown by the example of radioactive ⁹⁸Mo production in Mo⁹⁸Mo(n, γ)⁹⁹Mo reaction that for achievement of maximal yield of target radionuclide. it is necessary to irradiate start targets of Molybdenum in hard spectrum with essential contribution of resonance neutrons.