Titanium beryllide as an alternative to beryllium in nuclear and thermonuclear engineering, capabilities of UMP JSC in the technology development and beryllides products manufacture

For many decades, beryllium has been used as a structural element in nuclear installations as a moderator / breeder of fast neutrons. The consequence of neutron irradiation is a significant production of gas products in the form of helium and tritium, which leads to swelling and loss of strength properties of beryllium reflectors. The relatively low melting point of beryllium also imposes restrictions on the high-limit temperature regimes of the reactor core. As an alternative to pure beryllium, it is necessary to consider intermetallic compounds based on it, in particular titanium beryllide. Preliminary studies on the thermal desorption of helium and tritium from titanium beryllide have shown that this material has a much lower retention tendency and a lower release temperature. The higher melting point of titanium beryllide compared to pure beryllium is also an advantageous characteristic.Over the past years, UMP JSC, thanks to its research in this area, has achieved significant success in the development of technology for obtaining intermetallic billets and articles based on titanium and chromium beryllides. As a technology demonstrator, prototypes of structural elements of a helium-cooled blanket breeder module of the projected DEMO reactor were made by order of the Karlsruhe Institute of Technology, Germany.The advantages of titanium beryllide, as well as the success achieved in the production of billets and products from it, open up opportunities for a more extensive study of the nuclear, physical and mechanical properties of this material with the possibility of further use in nuclear technology, including thermonuclear reactors, and in high-temperature instrumentation.

Measurement of the spatial-energy distribution of neutrons in the irradiation channel of the critical facility

One of the basic installations of the Republican State Enterprise “Institute of Nuclear Physics” of the Ministry of Energy of the Republic of Kazakhstan is a critical assembly, which is a zero-power reactor. Desalinated water and beryllium serve as moderators and neutrons reflectors. The energy spectrum of neutrons in the core is thermal. The main purpose and area of application is the modeling and study of the neutronic characteristics of the cores of water-moderated research reactors of various types. The paper presents the results of experimental measurements of the spatial-energy distribution of neutrons in the dry, central channel of the critical assembly. Measurements of the neutron flux were carried out using activation foils for three energy groups of neutrons: thermal, epithermal, and fast. The measured thermal neutrons flux in the irradiation channel is ~ 3·108 cm‒2s‒1, and fast neutrons flux (with energies above 0.7 MeV) is ~ 8·108 cm‒2s‒1. The fraction of thermal neutrons in the integral flux was 0.23%, and the fraction of fast neutrons was 0.62%. In the axial distribution of thermal and fast neutrons, the maximum value of the neutron flux is 50 mm below the midplane of the core.

Recovering the performance of irradiated high temperature superconductors for use in fusion magnets

The magnets confining the plasma in future fusion devices will be exposed to a significant destructive flux of fast neutrons. Particularly, in cost efficient compact reactor designs, the degradation of the superconductor becomes an issue and directly impacts the commercial viability. We report on the influence of neutron radiation on the superconducting transition temperature, Tc, and the critical current density, jc, and discuss possibilities to counteract the degradation by thermal treatments. We found that the degradation in Tc and jc are closely related to each other, likely by the expected loss of superfluid density; thus, Tc is a very useful indicator for the magnets' degradation. It increases linearly with annealing temperature and around 25 % of the decrease can be recovered by annealing at 150 °C and about 60 % at 400 °C, which would more than double the magnet’s life time. However, a loss of oxygen has to be impeded in the latter case.

Analysis of the Appearance of Micronuclei in the Erythrocytes and Activity of Bone Marrow Cells Proliferation after the Prolonged Low Dose Fast Neutrons Irradiation of Mice

Purpose: To analyze the level of cytogenetic damage and the activity of bone marrow cells proliferation in C57BL/6 mice after prolonged fast neutrons low dose irradiation at 10–500 mGy. Material and methods: Male C57BL/6 mice at the age of 7–8 and 16 weeks were used in the experiments. Irradiation was carried out on an OR-M installation in the field of fast neutrons and gamma quanta using five Pu(α,n)Be radionuclide sources with a high fast neutron yield at a dose rate of 2.13 mGy/h. The frequency of polychromatophilic (PCE) and normochromic (NCE) erythrocytes with micronuclei (MN) and the ratio of PCE and NCE were analyzed using light microscopy after cytochemical staining of the bone marrow cells of control and irradiated mice. The proliferation activity of bone marrow cells was determined by the number of Ki-67+-cells. The parameters of the cell cycle and the level of apoptosis were studied after DNA staining with DAPI using flow cytometry. Statistical processing of the results was carried out according to the Student’s method using the computer program Origin. Results: It was found that prolonged irradiation of mice with fast neutrons at a low dose rate (2.13 mGy/h) at doses from 10 to 500 mGy after 24 h led to statistically significant increase in the frequency of PCE with MN at all studied doses. No dose dependence of this parameter was observed in the studied range. The increase in the frequency of PCE with MN at a dose of 500 mGy was prolonged and persisted for at least 72 h. A significant increase in the frequency of NCE with MN 24 h after irradiation was found only at a dose of 500 mGy, which persisted up to 48 h. At this dose, there was also a decrease in the number of nucleated cells in the bone marrow 24 – 72 h after exposure, a decrease in the number of Ki-67+-cells 24 h after irradiation of mice, a block of the cell cycle in the G2/M phase, and a decrease of cells in the G0/G1 phase, but after 48 h, there were no disturbances in the cell cycle. Conclusion: It has been shown that after a single total prolonged irradiation of mice at low doses (10–500 mGy), when analyzing the frequency of PCE with MN, cytogenetic damage is recorded in the bone marrow, which indicates the genetic danger of exposure to even such low levels of fast neutron irradiation. A decrease in Ki67+ cells and cell cycle arrest at the G2/M phase were found only after irradiation of mice at a dose of 500 mGy and only 24 h after exposure, while the number of nucleated cells in the bone marrow at this dose was reduced, at least to 72 h.

Prompt and delayed gamma rays induced by epithermal and fast neutrons with indium

The emission of prompt and delayed gamma rays from (n,γ) and (n,n´γ) reactions induced by irradiation of indium with epithermal and fast neutrons was investigated with the instrument FaNGaS operated at Heinz-Maier-Leibnitz Zentrum (MLZ) in Garching. The average neutron energy of the neutron spectrum was 2.30 MeV. The measurement was done at an angle of 90° between neutron beam and detector. A total of 136 prompt gamma lines from which 42 are related to the capture of epithermal and fast neutrons and 94 to the inelastic scattering of fast neutrons were detected together with the delayed gamma lines of the activation products 113mIn, 114m2In, 115mIn, 116m2In and 116mIn. Intensities and neutron spectrum averaged isotopic partial cross section of the gamma lines are presented. Additionally the neutron spectrum averaged cross sections of the reactions, 113In(n,n´)113mIn, 113In(n,γ)114m2In, 115In(n,n´)15mIn, 115In(n, γ)116m2In and 115In(n, γ)116mIn were determined from the corresponding delayed gamma rays of the formed isotopes as 143 ± 22, 288 ± 13 194 ± 18, 201 ± 10 and 508 ± 24 mb respectively. The various results obtained were found consistent with the literature data. However, our measurement indicate the need to reevaluate the cross section of the 115In(n,γ)116m2In reaction for thermal neutrons.

RIPTIDE: a novel recoil-proton track imaging detector for fast neutrons

Neutron detectors are an essential tool for the development of many research fields, as nuclear, particle and astroparticle physics as well as radiotherapy and radiation safety. Since neutrons cannot directly ionize, their detection is only possible via nuclear reactions. Consequently, neutron-based experimental techniques are related to the detection of charged particle or electromagnetic radiation originating from neutron-induced reactions. The study of fast neutrons is often based on the neutron-proton elastic scattering reaction. In this case, the ionization induced by the recoil protons in a hydrogenous material constitutes the basic information for the design and development of neutron detectors. Although experimental techniques have continuously improved and refined, so far, proton-recoil track imaging is still weak in laboratory rate environments because of the extremely small detection efficiency. To address this deficiency, we propose a novel recoil-proton track imaging system in which the light deriving from a fast scintillation signal is used to perform a complete reconstruction in space and time of the event. In particular, we report the idea of RIPTIDE (RecoIl Proton Track Imaging DEtector): an innovative system which combines a plastic scintillator coupled to imaging devices, based on CMOS technology, or micro channel plate sensors. The proposed apparatus aims at providing neutron spectrometry capability by stereoscopically imaging the recoil-protons tracks, correlating the spatial information with the time information. RIPTIDE intrinsically enable the online analysis of the ionization track, thus retrieving the neutron direction and energy, without spoiling the overall efficiency of the detection system. Finally, the spatial and topological event reconstruction enables particle discrimination — a crucial requirement for neutron detection — by deducing the specific energy loss along the track.

Feasibility Study of Copper-64 Radioisotope Production by Secondary Fast Neutron Bombardment

As a beta and positron emitter, copper-64 (Cu-64) has been coined a theranostic agent in nuclear medicine. Copper-64 is generally produced by bombarding a nickel-64 target with a proton beam via 64Ni(p,n)64Cu nuclear reaction. In this work, secondary fast neutrons are proposed to produce Cu-64 radioisotope via 64Zn(n,p)64Cu nuclear reaction. The secondary fast neutrons were produced by a 10 MeV proton-irradiated primary titanium (Ti) target simulated using the PHITS 3.16 code. In the simulation, the Ti target thickness was varied from 0.01 to 0.1 cm to obtain the optimum secondary fast neutron flux, which was calculated in the rear, radial, and front directions. The Cu-64 radioactivity yield was then computed using the TENDL 2019 nuclear cross-section data. Also, the expected radioactive impurities during Cu-64 production were predicted. The simulation results indicated that the total fast neutron flux resulted from the 10-MeV proton bombarded Be target was 1.70x1012 n/cm2s. The maximum integrated Cu-64 radioactivity yield was 2.33 MBq/µAh when 0.03 cm thick Ti target was shot with 10-MeV protons. The most significant impurities predicted during the bombardment were radioactive isotopes e.g., Co-61, and Zn-65, with the total radioactivity yield estimated to be 0.28 Bq/µAh.

Neutron/gamma radiation shielding characteristics and physical properties of (97.3–x)Pb–xCd–2.7Ag alloys for nuclear radiation applications

In this work, the shielding performance of (97.3–x)Pb–xCd–2.7Ag (x=10, 18, and 30) ternary alloys against neutrons and gamma rays has been investigated. The microstructure, thermal and mechanical properties of the ternary alloys were examined. The total mass attenuation coefficients, μ⁄ρ, for prepared alloys were determined at 662, 1173, and 1332 keV photon energies using NaI (Tl) scintillation detector. The theoretical values of μ⁄ρ were calculated using WinXCom program depending on the mixture rule. The estimated values were compared with the measured values for all investigated alloys. Atomic cross-section, σa, electronic cross-section, σe, effective atomic number, Zeff, effective electron number, Neff, and GP fitting parameters (b, c, a, Xk, and d) were determined. The exposure buildup factor, EBF, have been also calculated. Fast neutron attenuation for the prepared samples have been investigated via the macroscopic effective removal cross-section (∑_R) calculation. Also, thermal neutron attenuation has been evaluated via neutron scattering calculator. The results show that the alloys containing 10 and 30% Cd compromise between superior tensile strength and Young modulus, while the pasty range, heat of fusion and ductility decreased with increasing Cd content. Moreover, the prepared ternary alloys have a high attenuation ability for gamma rays as the standard Pb. The increase of Cd ratio also significantly enhances the thermal neutron attenuation by amazing way along with the increase in the attenuation rate of fast neutrons.