A description of the irradiation facility and available parameters of neutron and gamma exposures, including the maximum integrated doses, are presented in the paper. The research capabilities for radiation hardness tests of materials in a high-intensity beam of fast neutrons at the IBR-2 reactor of the Joint Institute for Nuclear Research in Dubna (Russia) are outlined.

Methodology and results of measuring the differential density of the neutron flux in irradiation beam line no. 3 of the IBR-2 reactor using neutron activation analysis (NAA) are presented in the paper. The results are compared to the calculation performed on the basis of the 3D MCNP model. The data that are obtained are required to determine the integrated radiation dose of the studied samples at various distances from the reactor.

In July 10, 2012 cold neutrons were generated for the first time with the unique pelletized cold neutron moderator CM-202 at the IBR-2M reactor. This new moderator system uses small spherical beads of a solid mixture of aromatic hydrocarbons (benzene derivatives) as the moderating material. Aromatic hydrocarbons are known as the most radiation-resistant hydrogenous substances and have properties to moderate slow neutrons effectively. Since the new moderator was put into routine operation in September 2013, the IBR-2 research reactor of the Frank Laboratory of Neutron Physics has consolidated its position among the world’s leading pulsed neutron sources for investigation of matter with neutron scattering methods.

The design and main characteristics of a test setup for studying the serviceability of the bead cryogenic neutron moderator and determining its optimal operating conditions on the fast pulsed IBR-2 reactor are presented. Using the test setup, the possibility has been demonstrated of filling the moderator chamber with the working medium—beads of a mixture of aromatic hydrocarbons, delivered to the chamber by a cold (T < 85 K) helium gas flow over an intricately shaped cryogenic pipeline system.

Experiments on production of long-lived Hf178m2 isomer in reactor irradiations are described. Properties of this nuclide are promising for its potential application as a relatively safe power source characterized by high density of accumulated energy. Metal natHf samples were activated in the Dubna IBR-2 reactor at positions corresponding to different neutron fluxes. Samples were bare or shielded by Cd and B4C layers. The gamma activity of the samples was analyzed with Ge gamma spectrometers during a two-year period following their irradiation. In the presence of dominant activation products 175Hf and 181Hf, the high-spin isomers Hf178m2 and Hf179m2 were also detected despite relatively low levels. The isomer-to-ground state ratios and cross-sections were determined from the measured yields. For Hf178m2, the cross-section for burnup (destruction) by neutron capture after its production was also estimated, clarifying the results from earlier experiments. In the context of suggestions for use of Hf178m2 for applications, the results confirm that large-scale production of this isomer by reactor irradiations is not feasible. In contrast, the efficiency of production of Hf179m2 is much higher and an amount of about 1016 atoms may be produced in standard reactor irradiations. For Hf178m2, more productive methods are known, in particular fast neutron irradiations at En≥14MeV and spallation reactions at intermediate energies. Neutron cross-sections for isomers may also be significant in astrophysics.

The URAM-2 irradiation system facility at the IBR-2 reactor is described. The results of experiments performed with this facility to study the behavior of water ice, solid methane, aromatic hydrocarbons, and other materials exposed to fast neutrons and γrays are presented. The rate of energy accumulation in these materials under irradiation and the amount of accumulated hydrogen and the temperature at which the hydrogen leaves the material matrices are determined. Recommendations are made for the working temperature of these materials for use in cold neutron moderators.

The second isomer (T-1/2 = 25.1 d) in Hf-179 is one of a number of nuclear states that is interesting from the point of view of triggering a release of "clean" nuclear energy because it stores a specific energy of about 0.5 MJ/mg. The yield of this isomer in nuclear reactions is restricted due to its high spin, I-pi = 25/2(-). The productivity of previously known methods was enough for the creation of experimental amounts but not for potential applications. In this paper, we show that irradiations in a reactor by the fast neutron flux within the fission spectrum are useful for the accumulation of Hf-179m2 in an amount of 10(16) nuclei. In an experiment performed in the Dubna IBR-2 reactor, the yield, cross-section sigma(m), and isomer-to-ground state ratio sigma(m)/sigma(g) were measured for the Hf-179(n, n,gamma)Hf-179m2 reaction. The systematics of the sigma(m)/sigma(g) values deduced from the experimental data available for this isomer are discussed.

The report continues our investigations of the thermometers which can be operated under conditions combining high radiation environment and cryogenic temperatures. To clarify temperature shifts due to fast neutron irradiation up to 10(16) n/cm(2), additional platinum, carbon-glass and TVO temperature sensors were tested. The selected sensors were preliminary calibrated, and a series of experiments were carried out with irradiation of the sensors at 77.3 K and 293 K when their readings were measured in-situ. The postradiation behavior of the sensors was estimated as well. The obtained results are discussed.

The irradiation facility at the beam line no. 3 of the IBR-2 reactor of the Frank Laboratory for Neutron Physics is described. The facility is aimed at irradiation studies of various objects with area up to 800 cm2 both at cryogenic and ambient temperatures. The energy spectra of neutrons are reconstructed by the method of threshold detector activation. The neutron fluence and γ dose rates are measured by means of alanine and thermoluminescent dosimeters. The boron carbide and lead filters or (nγ) converter provide beams of different ratio of doses induced by neutrons and photons. For the lead filter, the flux of fast neutrons with energy more than 0.1 MeV is 1.4 × 1010n cm−2s−1 and the neutron dose is about 96% of the total radiation dose. For the (nγ) converter, the γ dose rate is ∼ 500 Gy h−1 which is about 85% of the total dose. The radiation hardness tests of GaAs electronics and materials for the ATLAS detector to be put into operation at the Large Hadron Collider (LHC) have been performed successfully at this facility.

The present paper describes the installation for ultracold neutrons (UCN) at the SM-2 reactor of the Reactor Research Institute in Dimitrovgrad. Maximum UCN flux extracted was about 1200 s−1. Both integral and differential energetic spectra of the obtained beam were measured. The UCN transmission was determined for straight and bent guide tubes as well as the angular distribution of UCN at the exit of these guide tubes. It is shown that there exists an effect of beam alignment and a lower limiting in the neutron angular distribution at the guide tube exit. Results of a storage experiment in a vessel of about 3401 are reported.