A complex radiation diagnostics facility "DRAGON" has been constructed at the reactor IR-8. The facility includes 3 beams for measurements using neutron and gamma radiation. The parameters of the facility are presented; the main units of the facility are described. The results of radiographic and tomographic experiments on the setup are presented.

The medieval Russian bronze reliquary cross pendant was investigated using a complex of nondestructive methods in order to determine the degree its integrity and identify the material filling its internal cavity. The metal composition is established. It is found that the cross material was subjected to spatially inhomogeneous corrosion and that the cavity is filled with soil. It is shown that application of complementary nondestructive methods provides the most reliable information on historical heritage objects.

Changes in the structure and atomic dynamics of diamond irradiated by fast neutrons have been studied. It has been shown that a sample irradiated to a fluence of 1021 cm−2 holds the diamond crystal structure and change in the cubic cell parameter corresponds to a 5% increase in the atomic volume, which can be treated as the application of a “negative” pressure P < −25 GPa to the sample. It has been found experimentally that a peak in the phonon spectrum corresponding to optical modes of a crystal lattice is noticeably shifted toward low energies. The Grüneisen parameter for optical modes of diamond at negative pressure has been estimated. It has been established that the Grüneisen parameter of diamond in the pressure range of −25 GPa < P < 35 GPa does not change and is close to unity.

The crystalline and magnetic structure of the nonstoichiometric intermetallic compound Tm 2 Fe 18 has been investigated in the temperature interval from 3 to 300 K using the methods of neutron diffraction, synchrotron radiation, and ultra-small-angle neutron scattering. A theoretical interpretation of the spin-reorientation transition has been given and the value and temperature dependence of the first constants of magnetic anisotropy for the sublattices of iron and thulium have been determined. Based on the results of experiments and theoretical interpretation of small-angle neutron scattering, a conclusion has been made on a reconstruction of the domain structure upon spin-reorientation phase transition.

Residual stress instrument STRESS at 8 MW research reactor IR-8 at National Research Center "Kurchatov Institute" is described. Using double-crystal monochromator PG002(flat)/Si220(horizontal focusing perfect crystal), providing fixed neutron wavelength lambda - 1.56 angstrom, resulted in compact arrangement of the instrument, high intensity and low background. The experiments showed that in maximal available path length (76 mm in ferritic steel) the difractometer is comparable with other modern stress-difractometers at more powerful reactors.

The current state of neutron research at the IR-8 reactor is considered and it is shown that the research is focused on two main avenues: comprehensive radiation diagnostics for the sake of those knowledge domains which have not used it before and research of the structure of material under extreme conditions (high pressures, strong magnetic fields, and irradiation). Case studies are given in the areas of materials technology, geology, paleontology, archaeology, and medicine, as well as studies of materials under thermobaric impact and self-radiation. The possibilities of a combination of different experimental techniques are discussed.

The most important results of tomographic studies of paleontological objects on the facilities of the National Research Centre “Kurchatov Institute” are described. It is shown that the use of the synchrotron and neutron tomography makes it possible to obtain new information on the structure of fossil animals, which is of fundamental importance for taxonomy and morphological analysis of extinct fauna.

Prospects for creating a Kurchatov Institute Neutron Center based on the IR-8 reactor with a hydrogen cold neutron source, neutron guides, and new experimental facilities in the neutron guide hall and the reactor hall are discussed. Such a center will have a wide range of equipment enabling research using various new techniques, both in core aspects and in the area of nanotechnologies, surface physics, and study of material in extreme conditions.

Phase transformations of the amorphous phase of fullerene C-70 at high temperature (HT) (up to 1100 degrees C) and high pressure (HP) (2-8 GPa) have been investigated and compared with the previous studies on the crystalline phase of fullerene C-70. The amorphous phase of fullerene C-70 was obtained by ball-milling. The study was conducted using neutron diffraction, Raman spectroscopy and HRTEM. It was shown that under the influence of HT and HP, the amorphous-like phase of fullerene C-70 retains an amorphous structure up to 500 degrees C and transforms at temperatures 800-1100 degrees C into amorphous-like or nanocrystalline graphite. The interesting difference of the transformation of the amorphous and crystalline phases of C-70 is the structure of formed amorphous-like graphite. These types of amorphous-like graphite differ in the type of neutron diffraction patterns and in the presence or absence of graphite nanoclusters. An explicit anisotropy of amorphous-like graphite is revealed, which is manifested in the dependence of the diffraction patterns on the direction of measurement of the diffraction pattern in the sample under study. The introduction of deuterium affects the structure and diffraction spectra of amorphous-like graphite formed at HTHP.

The problem of developing a dedicated neutron diffractometer for placement on a horizontal reactor channel to measure internal stresses in bulk materials and components under conditions of a limited space is considered. It is shown that the use of a double-crystal monochromator composed of pyrolytic graphite and a focusing bent perfect silicon single crystal is the optimal solution to this problem. The diffractometer with such a monochromator that is installed at the IR-8 reactor of the National Research Center Kurchatov Institute is comparable in luminosity and resolution at a reactor power of 6 MW to modern stress diffractometers at more powerful reactors.

The interaction of hydrogen with ZrMo2 intermetallic compound at pressure up to 2500 bars has been studied. In ZrMo2-H-2 system desorption isotherms were measured and thermodynamic parameters of hydride phase decomposition were calculated. The structure of ZrMo2D4.0 deuteride has been investigated by X-ray and neutron diffraction methods. It was revealed that ordering of deuterium in the cubic lattice of ZrMo2 led to the formation of superstructure with tetragonal lattice. The occupancy of the positions of deuterium and metal atoms was determined. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

The effect deuterium has on phase transformations is studied for amorphous and crystalline fullerenes C60 and C70 at high temperatures of up to 1300°C and high pressures (2–8 GPa). Amorphous fullerene phases are obtained via long grinding in a planetary mill. Structure is studied by means of neutron diffraction. In all cases, amorphous graphite (nanographite) forms in the temperature range of 800–1100°C. This material has different diffraction spectra distinguished by the heights of the halos observed on the graphite diffraction maxima and their relative intensities. These spectra (the structure of nanographite) are affected by preliminary amorphization, the number of carbon atoms in the fullerenes (C60 or C70), and the introduction of deuterium atoms. The different spectra of amorphous (disordered) graphite testify to its varying structure.

The ultrasmall- and wide-angle neutron diffraction methods are used to study multiscale structures and phase transformations in synthetic opals at different temperatures and pressures (as high as 1500°C and 10 GPa, respectively). Monodisperse colloidal particles of amorphous silica dioxide (a-SiO2) with an average diameter of 150‒1700 nm whose deviation from the mean is less than 5% are synthesized to fabricate the samples. Opal matrices up to 3 cm thick are obtained via the natural sedimentation of a SiO2-globule suspension followed by drying and heat treatment. Neutron-diffraction processes are investigated using a DISK multidetector superposition diffractometer mounted at the IR-8 reactor of the National Research Centre Kurchatov Institute at a neutron wavelength of 1.668 Å. Ultrasmall-angle diffraction experiments are performed in the two-crystal mode of a STOIK spectrometer.

Structure of smooth hydrocarbon CD x films with a high deuterium ratio x ~ 0.5 redeposited from T-10 tokamak D-plasma discharges (NRC Kurchatov Institute, Moscow) has been studied. For the first time, small and wide angle X-ray scattering technique using synchrotron radiation and neutron diffraction have been employed. A fractal structure of CD x films is found to consist of mass-fractals with rough border, surface fractals (with rough surface), plane scatterers and linear chains forming a branched and highly cross-linked 3D carbon network. The found fractals, including sp2 clusters, are of typical size ~1.60 nm. They include a C13 fragment consisting of three interconnected aromatic rings forming a minimal fractal sp2 aggregate 9 × C13. These graphene-like sp2 clusters are interconnected and form a 3D lattice which can be alternatively interpreted as a highly defective graphene layer with a large concentration of vacancies. The unsaturated chemical bonds are filled with D, H atoms, linear sp2 C=C, C=O, and sp3 structural elements like C-C, C-H(D), C-D2,3, C-O, O-H, COOH, C x D(H) y found earlier from the infrared spectra of CD x films, which are binding linear elements of a carbon network. The amorphous structure of CD x films has been confirmed by the results of earlier fractal structure modeling, as well as by researches with X-ray photoelectron spectroscopy which allow finding a definite similarity with the electron structure of their model analogues — polymeric a-C:H and a-C:D films with a disordered carbon network consisting of atoms in sp3 + sp2 states.