Kazakhstan is known as a country with a complex radioecological situation resulting from different sources such as a natural radiation background, extensive activities of the industrial system of the former Soviet Union and a well-known testing of nuclear power weapons occurred in the Semipalatinsk Test Site (STS) area. The present study focuses on the assessment of the background of dicentric chromosomes in Kazakhstan’s population, which is the starting point in the dose assessment of irradiated people, since the baseline level of spontaneous dicentrics can vary significantly in different populations. In this context, aiming to determine the background frequency of chromosome aberrations in the population of Kazakhstan, considering the heterogeneity of natural radiation background levels of its large territory, a selection of 40 control subjects living in four cities of North, South, West and East Kazakhstan was performed. The cytogenetic study on the selected groups showed fairly low background frequency values of chromosome aberrations (0.84 ± 0.83 per 1000 cells), comparable with other data in the literature on general populations, reporting background frequency values between 0.54 and 2.99 per 1000 cells. The obtained results should be taken into account when constructing the dose–effect calibration curve used in cytogenetic biodosimetry, as a “zero” dose point, which will reduce the uncertainty in quantifying the individual absorbed dose in emergency radiological situations.

The results of research on the application of the method of measurement of gross alpha-, beta-activity in water using the liquid scintillation counter (LSC) Quantulus 1220 are presented. Basic procedures of preparation and spectrometric measurement of aqueous samples were studied and performed. The detection efficiency of alpha-, beta-particles depending on quenching and the optimum alpha-, beta-radiation separation parameter for the method used were determined. Testing and validation of the technique was carried out on model solutions with different concentrations and composition of alpha- and beta-emitters, as well as by participating in interlaboratory comparisons. The results demonstrated that the use of LSS allows for a sufficiently fast and accurate estimation of the gross alpha- and beta-activity in water below the regulated limits without the use of labor-intensive sample preparation.

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The article presents results of the study of the effect of LED power modes based on AlGaAs heterostructures (short-circuit, open circuit, and active mode with the passage of operating current during irradiation) on the resistance to γ-n-pulse exposure. Reduction of LED emission power under the influence of γ-n-pulse occurs in two stages irrespective of irradiation power mode, with each stage characterized by its own regularity and its own factor. Built-in electric field of p-n-junction does not contribute significantly to the degradation of LED power when exposed to γ-n-pulse. At irradiation of LED in active power mode after exposure to γ-n-pulse (Fn ≤ 1.5·1012n/cm2, Dγ ≤ 20 Gy (Si)) a recovery of LED power by the value of ΔP is observed. Recovery of ΔP power leads to reduction of the damage factor at the first stage, to increase of the LED resistance, and to shift of the boundary between the stages to the area of higher neutron fluences. It is supposed, that the observed jump-like increase of ΔP radiation power under the influence of γ-n-pulse is caused by radiation-stimulated annealing of local mechanical stresses that is generated under the condition of passing of operating current through LED.