[en] Technical peculiarities of experiments on determination of neutron-physical parameters for heterogeneous lattices are considered and the experiments with the uranium-thorium-graphite RBMK type polylattices are described. Three variants differing in thorium content in a polycell, a polycell arrangement and a structure of channel with thorium are investigated. Using as an example one of the lattices, the effect of channel dewatering on neutron-physical parameters is studied. Distributions of different-energy neutrons over the cell radius (microdistribution) and macrodistributions of neutron flux density, as well as balance ratios of ²³²Th, ²³⁵U and ²³⁸U, are determined. The data obtained can be used for testing the computer programs for calculating heterogeneous reactor lattices and thorium constants

[en] Modification of methodology, including gamma- and roentgenospectrometry of ²⁴¹Am and relative content of Pu/²⁴¹Am for determination of specific activity of ²⁴¹Am and plutonium isotopes in the soil samples is substantiated. The possibilities of the above methodology are studied and comparison with the traditional radiochemical methodology is given

[en] Gamma radiation spectral measurements of uranium and plutonium samples irradiated by neutrons of ²⁵²Cf source are described. Peaks of ¹³⁸Cs and other short-lived fissile products are observed in spectra. Content of fissile isotope in the samples was characterized by the intensity of peaks

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[en] Results of the experimental investigation of the resonance neutron absorption in the fuel of a high-temperature graphite reactor (HTGR) are presented. Data on the resonance neutron absorption in the HTGR fuel are obtained according to measurements with certain irradiated microfuel elements. Irradiation has been conducted in the experimental channel in the centre of the reactor. Micro-fuel element gamma-radiation has been measured using a Ge(Li) spectrometer. Resonance integrals of ²³⁸U capture and ²³⁵U fission depending on the microfuel element mass are measured. The dependence of the resonance microfuel element integral on its temperature at 300-1500 K is investigated. The resonance integral dependence of the spherical HTGR fuel element on the uranium content at 500-1500 ratio of carbon and uranium concentration is determined. A conclusion is made on fitness of calculation methods where equivalence ratio is used for description of the resonance neutron absorption in the fuel basing on the comparison of the data obtained with the calculation results

[en] Design and theoretical, as well as experimental, investigations of the integral parameters of carbon-uranium systems with a different number of cells have been carried out to ascertain the influence of heterogeneity and the possibility of using the theory of the material parameter when analysing results obtained for heterogeneous subcritical systems. The Galanin-Feinberg method has been used in the theoretical analysis of the heterogeneity effects. The experiments designed to study the influence of the number of cells on the parameters measured have been carried out on subcritical carbon-uranium systems with natural uranium using a reactor neutron beam. The number of cells varies from 9 to 81, the system height being 270 cm. The cadmium ratio Rsub(Cd)sup(28) and / has been measured. The parameter Rsub(Cd)sup(28), being the most sensitive one to changes in the dimensions of the system, remains unaffected with 25 cells or more. The results of the relative measurements of Rsub(Cd)sup(28) are in reasonable agreement with the data from the heterogeneity calculations

[en] γ-Radiation spectra of spontaneously fissionable ²⁵'2Cf and Pu samples with different isotope ratio (²³⁸Pu, ²⁴⁰Pu, ²⁴²Pu) were measured. Peaks of the fixed fission products were identified in spectrum. Conclusion on the possibility of control over mass and isotope ratio of massive samples from the results only γ-spectrometric measurements was made

[en] Possibility for the application of activation γ-spectrometric procedure for the determination of nuclear materials content in samples was studied. Using temporary irradiation of samples by slow neutrons of the Pu-Be-source by the ∼ 10⁷ s^-1 intensity good for the measurement ¹³⁸Cs γ-radiation with 1436 keV is started, mass of nuclear materials is determined using intensity of this radiation. Three series of experiments with sets of metal uranium and uranium dioxide samples of different enrichment and mass are presented. As experiments demonstrated the error of uranium determination is as much as 1 - 3 % on period of irradiation 30 - 60 min and the same duration of measurement. Special experiments on the investigation into the effect of geometry of test and γ-radiation self-absorption in the sample on possibilities of γ-spectrometric measurements of nuclear materials samples are conducted

[en] In this work is described the procedure called 'Express estimation of minimum detecting activity of Sr 90 on Expert beta-gamma-whole-body-counter'. This procedure is one of the methods for determination of minimal detected activity of Sr 90 taking into account anthropometric description data of human's body and consideration, that this radionuclide is distributed even over the skeleton. (authors)

[en] This article describes the algorithm of estimation error at the operations with beta-spectrums, as well as compares the theoretical and experimental errors by the data handling of beta-channel. (authors)