G. G. Bondarenko

Effect of the Electron Decay of Metallic Fission Products on the Chemical and Phase Compositions of an Uranium-Plutonium Fuel Irradiated by Fast Neutrons

After fast-neutron irradiation, uranium-plutonium nitride U0.8Pu0.2N is shown to acquire a complex structure consisting of a solid solution that is based on the nitrides of uranium, plutonium, americium, neptunium, zirconium, yttrium, and lanthanides and contains condensed phases U2N3, CeRu2, BaTe, Ba3N2, CsI, Sr3N2, LaSe, metallic molybdenum, technetium, and U(Ru, Rh, Pd)3 intermetallics. The contents and compositions of these phases are calculated at a temperature of 900 K and a burn-up fraction up to 14% (U + Pu). The change in the composition of the irradiated uranium-plutonium nitride is studied during the electron decay of metallic radionuclides. The kinetics of transformation of U103Ru3, 137CsI, 140Ba3N2, and 241PuN is calculated.

Simulation of charged and excited particle transport in the low-current discharge in argon-mercury mixture

Simulation of the electron, ion and metastable excited atom transport in the argon-mercury mixture low-current discharge is fulfilled. Distributions of the particle densities along the discharge gap under different mixture temperatures are obtained and it is demonstrated that the principal mechanism of mercury ion generation is the Penning ionization of mercury atoms by argon metastables, which contribution grows sharply with the mixture temperature due to mercury density increase. Calculations show that the mercury and argon ion flow densities near the cathode are of the same order already under the relative mercury content of about 10−4 corresponding at the argon pressure 103 Pa to the mixture temperature 30 C. Therefore, at the room temperature the electrodes of mercury illuminating lamps at the stage of their ignition are sputtered predominantly by mercury ions.

Features of the Damage and the Structural Changes in the Tungsten Surface Layer under the Pulsed Action of Laser Radiation,Ion and Plasma Fluxes

The degradation of a bilateral pressed tungsten surface layer by pulsed laser irradiation in the free-running mode (power density q = 105–5 × 106 W/cm2, pulse duration τ = 0.7 ms) and the Q-switched mode (q = 109–1010 W/cm2, τ = 80 ns) as well as under plasma beam irradiation in a plasma focus (PF) device (q = 108–1012 W/cm2, τ = 10–100 ns) has been investigated. The features of the degradation, erosion, and structural changes in the tungsten surface layer under different irradiation conditions have been determined. It has been shown that the use of PF devices in combination with laser equipment is promising for the simulation of the extreme radiation–thermal effects in materials that are typical of thermonuclear fusion devices with magnetic and inertial plasma confinement.

Influence of Temperature on the Ionization Coefficient and Ignition Voltage of the Townsend Discharge in an Argon–Mercury Vapor Mixture

The kinetics of main types of charged and excited particles present in a low-current discharge in an argon–mercury vapor mixture used in gas-discharge illuminating lamps has been investigated in a wide interval of the reduced electric field strength and temperature. Mechanisms behind the production and loss of ions and metastable atoms have been discovered, and the temperature dependences of their contributions to maintaining their balance have been determined. It has been shown that, when the discharge is initiated in the lamp and the mercury content in the mixture is low, the ionization coefficient exceeds that in pure argon, which is almost exclusively due to the Penning reaction. The influence of this reaction grows with a reduction of the electric field strength in the interelectrode gap. The dependences of the discharge ignition voltage on the interelectrode gap (Paschen curves) for different temperatures of the mixture have been calculated, and the nonmonotonicity of the temperature dependence of the ignition voltage has been explained.

Structural Changes in the Vanadium Sample Surface Induced by Pulsed High-Temperature Deuterium Plasma and Deuterium Ion Fluxes

The structural changes in the vanadium sample surface are studied as functions of the conditions of irradiation by pulsed high-temperature deuterium plasma and deuterium ion fluxes in the Plasma Focus installation. It is found that processes of partial evaporation, melting, and crystallization of the surface layer of vanadium samples take place in the plasma flux power density range q = 108–1010 W/cm2 and the ion flux density range q = 1010–1012 W/cm2. The surface relief is wavelike. There are microcracks, gas-filled bubbles (blisters), and traces of fracture on the surface. The blisters are failed in the solid state. The character of blister fracture is similar to that observed during usual ion irradiation in accelerators. The samples irradiated at relatively low power density (q = 107–108 W/cm2) demonstrate the ejection of microparticles (surface fragments) on the side facing plasma. This process is assumed to be due to the fact that the unloading wave formed in the sample–target volume reaches its irradiated surface. Under certain irradiation conditions (sample–anode distance, the number of plasma pulses), a block microstructure with block sizes of several tens of microns forms on the sample surfaces. This structure is likely to form via directional crack propagation upon cooling of a thin melted surface layer.

Study of deuterium and hydrogen distributions in Ta|CD2|Ta, Ta|Ta|CD2|Ta|Ta, and Nb|CD2|Nb assemblies after exposure to high-temperature argon plasma

Assemblies made of Ta|CD2|Ta, Ta|Ta|CD2|Ta|Ta and Nb|CD2|Nb foils are irradiated with pulses of high-temperature argon plasma created by means of a “Plasma Focus” setup. The irradiated foil samples are investigated by recording the recoil nuclei of hydrogen and deuterium. It is found that hydrogen and deuterium are redistributed in foil stacks. The ultradeep penetration of light gas impurities (hydrogen and deuterium) can be explained by the influence of shock waves on the foils and accelerated diffusion under an external force.

Attenuation of photon and neutron radiation using iron–magnetite–serpentinite radiation-protective composite

The attenuation coefficients of photon and neutron beams as they pass through the iron–magnetite–serpentinite cement concrete (IMSCC), which is used for biological protection of nuclear reactors, are calculated. Compton scattering makes the main contribution to attenuation of the beam at γ-photon energies lying in the range of 0.2–11 MeV, while at photon energies higher than 11 MeV the main contribution to attenuation of beam is made by the effect of formation of electron–positron couples. It is shown by assessing the influence of fast neutrons that, despite the low density of hydrogen in the composite under study, the contribution of hydrogen to the attenuation coefficient of the neutron flux is very important. It is connected both with the high hydrogen concentration and the fact that higher kinetic energy is transferred to light atomic nuclei than to heavy ones under neutron irradiation.

Modification of MIS structures by electron irradiation and high-field electron injection

The change in the charge state of metal–insulator–semiconductor (MIS) structures with a two-layer silicon-dioxide–phosphosilicate-glass gate insulator upon their modification under electron irradiation and high-field electron injection is studied. A thin glass film is formed by doping a thermal SiO2 film formed on the surface of a silicon wafer with phosphorus. It is found that the negative charge accumulated in a thin film of phosphosilicate glass during high-field tunneling electron injection or electron irradiation can be used to adjust the threshold voltage and to increase the charge stability and the breakdown voltage of MIS devices. It is shown that MIS structures need to be annealed at a temperature of approximately 200°C to obtain high thermal-field stability after modification of their charge state by the electron injection or electron irradiation. It is found that the use of a two-layer silicon-dioxide–phosphosilicate-glass gate dielectric increases the average value of the charge injected into the insulator to breakdown and decreases the amount of defect structures.

Modification of thin oxide films of MOS structure by high-field injection and irradiation

We have investigated processes of modification and changing of the charge state of MOS structures having a multilayer gate dielectric based on a thermal SiO2 film doped with phosphorus under conditions of different modes of high-field electron injection and an electron irradiation. We have determined that negative charge, accumulating in the phosphosilicate glass (PSG) ultra thin film of the MOS structures having the two-layer gate dielectric SiO2-PSG under conditions of both high-field tunneling injection of electrons and electron beam, could be used for a modification of devices having the same structure (e.g. correction of threshold voltage, increase of charge stability and breakdown voltage of MOS structure). We have shown that when thickness of PSG film increased, a raising of the electron traps density occurred, but the value of the cross-section of electron traps was the same. It was established that in order to obtain MOS structures with high thermal stability, one has to anneal them at 200° C after performing irradiation treatment.

Transport packing set for radioactive waste based on a radiation-protective polymeric matrix

This article considers the possibility of using a neutron-protective polymeric cover for transport packing sets (containers) of spent nuclear fuel (SNF). It is confirmed that it is possible to synthesize highly dispersed hydrophobic metal organosiloxane powders that have a chain silicate containing chemically bonded gadolinium with a high concentration of gadolinium atoms in the polymeric volume. Scientific foundations for modification of the structure and properties of polymeric composites are developed which provide for directed regulation of their supramolecular structure by introducing plasticizing and modifying additives. Design and experimental studies on the neutron-protective properties of the developed polymeric composite are conducted.