An Acoustic Converter Used to Measure Ionizing Radiation Energy Loss

A monitor is proposed based on ultrasonic production when ionizing radiation passes through a medium. The recording element is a 0.2 mm aluminum plate mounted in a ceramic acoustic converter AC in the form of a wedge of thickness 2 mm. The low plate thickness minimizes the beam parameter distortion, while special technology used in the AC provides high sensitivity. The device has been calibrated in the proton beam from the ITEP accelerator at 200 MeV with 2·10⁹–6·10¹⁰ particles in a pulse and a pulse length of 70 nsec.     

Oxidation of methane in a wide range of pressures and effect of inert gases

The analysis of methane oxidation in a wide range of pressures (0.05–10 atm) demonstrates that the efficiency of CH₃ radicals recombination is of great importance for high selectivity of C₂ hydrocarbons formation. The relative efficiency of different “colliders” assisting the stabilization of exited C₂H*₆ molecules increases in the series: solid surface> Ar> He. The increase of the overall reaction rate upon increasing pressure of the inert gases in the case of catalysts having a higher surface area and more developed pore structure is likely due to the contribution of the surface-induced chain reaction in the volume of pores.     

Concept of a multitask grid system with a flexible allocation of idle computational resources of supercomputers

A new concept of a multitask distributed heterogeneous computing system is proposed. The basic principles of such system are that it uses only idle supercomputer resources and does it as a common user; thus, it does not conflict with the administration policy in any way. The efficiency of the proposed concept is demonstrated by the example of the real grid system that currently uses supercomputer resources to boost the performance of the SAT@home and OPTIMA@home volunteer distributed computing projects.     

Prospective Power-Reactor Fuel Cycles Based on Water-Free Reprocessing of Spent Fuel

A pyroelectrochemical process for reprocessing spent fuel and fabricating granular oxides UO₂, PuO₂ or (U, Pu)O₂ from chloride melts has been developed at the Scientific-Research Institute of Nuclear Reactors for a prospective nuclear fuel cycle. The basic equipment has been developed. The basic results of a comprehensive study of fuel elements with vibrationally compacted (U, Pu)O₂ fuel for fast reactors are presented. The performance of the reactors remains high up to 30% burnup in standard BOR-60 reactor fuel assemblies and 32% burnup in experimental fuel elements. An assessment is made of the effectiveness of the pyroelectrochemical methods and vibrational compaction technology for plutonium utilization.     

Stripping of Pu and Tc from tributyl phosphate solutions with carbohydrazide

Stripping of Pu from 30% tributyl phosphate solutions with carbohydrazide was studied. The degree of the Pu stripping drastically decreases with an increase in acidity and increases with an increase in the carbohydrazide concentration and in temperature. The Pu(IV) reduction rate in the two-phase system is sufficiently high to perform the reductive stripping of Pu with carbohydrazides both in mixer-settlers and in centrifugal extractors. Stripping of Tc at high phase ratio (O/W = 30) with carbohydrazide, hydrazine, and U(IV) in a mixture with hydrazine was studied. At low acidity (<1 M HNO₃) and 30?C35°C, carbohydrazide allows more than 80% stripping of Tc from 30% TBP solutions even at high volume ratio of the phases.     

Intrinsic second-order nonlinearity in chalcogenide glasses containing HgI2

Frequency conversion using nonlinear optical (NLO) crystals is widely used in advanced photonic technologies to produce coherent light in the spectral regions where the available laser sources are missing. Isotropic glasses usually do not show second order nonlinear processes like second harmonic or difference frequency generation (SHG, DFG) except for temporarily induced anisotropy under external stimuli. Here, we show that a HgI₂–Ga₂S₃–GeS₂ homogeneous glass exhibits a strong intrinsic SHG response comparable with that of the well-known NLO single crystal LiNbO₃. The origin of this extremely rare phenomenon seems to be noncentrosymmetric bent HgI₂ molecules embedded in a sulfide glassy host. Taking into account the unique properties of chalcogenide glasses (wide IR transmission, low phonon density, unlimited ability to be modified changing the appropriate glass properties, fiber drawing and thin layer design), the observed phenomenon opens up the possibility of creating fundamentally new devices for mid-IR photonics.     

Pretreatment of rice husk in a pilot scale mill for further enzymatic hydrolysis

The effect of the mechanical activation of rice husk on the reactivity of its carbohydrates was studied. The activation was performed in a pilot-scale centrifugal roller mill. The mechanical treatment of the raw material led to an increase in its reactivity due to the increase in the specific surface area and amorphization of the crystalline regions of cellulose. The optimum process conditions of activation, leading to the preparation of a reactive product from rice husk, were determined: rotor frequency 1500 rpm, raw material feed rate 30 kg/h. The rice husk particles were ground to 45–50 μm under these conditions. These changes led to a sevenfold increase of the yield of low-molecular carbohydrates in the complete enzymatic hydrolysis of the material.