[en] The research reactor WWR-M of the Institute for Nuclear Research of the National Academy of Sciences of Ukraine (NASU) has been in operation for more than 47 years. Ukrainian legislation demands the decommissioning plan for nuclear installation at the operation stage. Initial decommissioning planning for WWR-M was performed in the framework of the Decommissioning Concept issued in 2001. Currently the Decommissioning Program (DP) has been elaborated. On the basis of selected decommissioning strategy, the DP determines and substantiates the principal technical and organizational measures on the preparation and implementation of the WWR-M decommissioning, the chain of decommissioning stages, the sequence of planned works and measures as well as the necessary conditions and infrastructure for its provision and safe implementation. (author)

[en] The structure of ¹¹⁷Sb levels populated in the reaction ¹¹⁵In(α, 2nγ) at E_α = 27.2 MeV is investigated. Data on γγ coincidences and the angular distributions of γ rays are used to construct the energy-level diagram and to determine the multipole orders of various transitions and the quantum numbers of levels. The positive-parity band based on the 9/2⁺ level is observed up to I = 23/2. A new band is revealed that is probably based on one of the isomer states. The levels of ¹¹⁷Sb are interpreted in terms of the coupling of a proton to vibrations of the core or to three-quasiparticle excitations. Identical bands in the neighboring isotopes of Sb are discussed. 26 refs., 7 figs., 3 tabs

[en] The WWR-M research reactor at the Institute for Nuclear Research is one of the first research reactors constructed and commissioned in the former USSR. The reactor was commissioned in 1960. At present, the reactor is a unique nuclear installation in the Ukraine due to its technical parameters and skilled staff. Future safe reactor operations require the replacement of obsolete equipment that was not upgraded during the last modernization. The current condition of the reactor allows for its safe operation for at least 8-10 more years if some systems and elements are upgraded. Extending reactor operations till 2015 is now considered to be the strategic goal. A coherent approach for the reactor modernization is in progress now. Previously, the Institute for Nuclear Research undertook several measures to improve both reactor and radiation safety. The current project includes the design of the control rod system equipment and renewal of an existing one; namely, the replacement of the current control rod system in the technological programme for automatic regulation, control, drive, and protection. (author)

[en] Both the description of and the operational experience with the radiation protection system at the research reactor WWR-M are presented. The list of the factors regarding the radiation hazards during the reactor routine operation is given and the main activities on the radiation safety provision are established. The statistical information for the staff exposure, the radioactive aerosol releases and the external radiation monitoring is shown. The preliminary considerations on the system upgrading for the decommissioning are presented. (author)

[en] The research reactor WWR-M of the Institute for nuclear research of the National Academy of Sciences of Ukraine is one of the first research reactors built and commissioned in the former USSR. Reactor was commissioned in 1960 and represents a heterogeneous water-moderated research facility operating with thermal neutrons at a power of 10 MWt, giving a maximum neutron flux of 1.5x10¹⁴ ncm^-2 s^-1 at the core centre. Reactor has nine horizontal experimental channels, a thermal column, and 13 vertical isotope channels inside the beryllium reflector. It is possible to install 10-12 vertical channels in the core. (authors)

[en] The investigations, initiated in, of the deuteron excitation functions for nuclear reactions with interaction energies of up to several tens of MeV were continued. The aim of the investigations is to obtain experimental data that can be used to determine the concentration of nuclides forming as a result of the transmutation of nuclei of the deuteron-irradiated material as well as to study the possibilities of predicting the data theoretically. In the present work we measured the excitation function for reactions in which long-lived nuclides are formed under irradiation of tin by deuterons. Calculations of the excitation functions were performed on the basis of the model of pre-equilibrium emission of nucleons and evaporation of nucleons and γ-rays from the compound nucleus using the program ALICE LIVERMORE. Conclusions are drawn on the basis of a comparison of the measurements and calculations about the role of the compound-nucleus mechanism in reactions with deuterons on tin and the possibility of using the ALICE LIVERMORE program for predicting reaction excitation functions. Thus far the only such investigation for tin is the experiment performed with deuteron energies up to 13.6 MeV

[en] The total cross sections of nuclear reactions in the energy range between several MeV and several tens of MeV have not been sufficiently studied at the present time. In many cases there are no experimental data. There is often a question of accuracy with which the cross sections can be calculated using theoretical models. At the same time, these types of nuclear constants are essential for the development of every nuclear technology. In the present work, an excitation function of nuclear reactions has been experimentally studied by the formation of long-lived radionuclides from the interaction of 47 MeV deuterons with zirconium of natural isotopic abundance. The experimental results are compared with theoretical calculations performed within the framework of a preequilibrium emission model and the evaporation of particles from a compound nucleus. Earlier an analogous study of the excitation function of proton-induced reactions was conducted

[en] Results of conservative personnel dose estimations for two decommissioning variants (immediate and deferred dismantling) of the VVER-1000 unit in Ukraine are presented. It was assumed that the dismantling would start within 10 and 40 years at after the unit's final shut down in the first and second variants, respectively. Estimated collective personnel doses for these variants are about 14.3 and 6.1 manSv. Man-hours and doses for the decommissioning of unit's components as well as the RAW and SNF site storage facilities are presented. Regardless of the fact that the personnel dose estimations are conservative, its ratio and component proportions are realistic and it can be used for the selection of optimal decommissioning strategy for VVER-1000 unit in Ukraine. (author)

[en] The results of in-beam investigations of ¹¹³Sn using the (p,n), (p,3n), (α,n) and (α,2n) reactions are summarized. Excited states have been identified until E_x=4715 MeV and J^π=(27/2^-). For a large number of levels mean lifetimes τ have been determined with the DSA method. For the J^π=25/2⁺ state at E_x=4059 MeV, τ=1.0(4) ns has been measured with the γ-RF method. The experimental results are compared with the predictions of shell-model calculations. Most of the positive-parity states may be considered as one- or three-quasiparticle neutron excitations of the 2d_5/2, 1g_7/2, 3s_1/2 and 2d_3/2 shells, the negative-parity states as the coupling of one 1h_11/2 neutron to the two- or four-quasiparticle neutron excitations in the even-mass ¹¹²Sn core. For the 25/2⁺ isomer the three-quasiparticle neutron configuration ν(h²_11/2 g^-1_7/2) has been proposed on the basis of a shell-model analysis using the mass-formula formalism. The experimentally observed yrast states in ¹¹³₅₀Sn₆₃ are compared with the corresponding states in the valence mirror nucleus ¹⁴⁵₆₃Eu₈₂ giving remarkable similarities although the parameters for the shell-model calculations differ considerably. The analysis of nearest-neighbour spacing distributions of experimentally obtained 5/2⁺ states in ¹¹³Sn does not allow definite conclusions about regularity or chaos. (orig.). With 9 figs., 2 tabs