Advanced Materials Research Vol. 1084

Abstract: One of the problems in developing the neutron capture therapy (NСT) of malignancies is the absence (or unavailability) of neutron sources having necessary intensity and spectrum. The first (and the only so far) experimental medical irradiation units for neutron capture therapy in Russia were created at IRT MEPhI nuclear reactor. At the exit of the tangential channel, there is a device for irradiating superficial tumors by thermal neutrons. A combined beam of thermal and epithermal neutrons that allows processing deep-lying tumors was implemented on the basis of a thermal column.

Abstract: The results of simulation of IRT-T reactor conversion from highly enriched fuel to new perspective low enriched fuel based on uranium-molybdenum alloy are given. Main characteristics of reacting core with the use of highly enriched and low enriched fuel are calculated. It is shown that impact of using new materials in fuel composition remains neutronic and thermal hydraulic characteristics of the core at an acceptable level.

Abstract: The neutron transmutation doping (NTD) of silicon is usually used for producing different electronic devices like thyristors, VLSI, detectors, etc. This article focuses on the formation of the radiation field to create the technology for silicon NTD implementing a pool-type nuclear reactor. The works includes the analytical consideration of the conditions for achieving the high radial irradiation uniformity of silicon ingots.

Abstract: This paper describes a method of determining the correlation of the exhausted graphite fuel blocks’ lifespan in high temperature gas-cooled reactors with the fuel burnup. The axial distribution of the local values of the exhausted lifespan of graphite fuel blocks was obtained. It is shown that for ensuring the compliance of the design value of the fuel burnup with graphite fuel blocks operability, it is necessary to reduce the average mixed temperature of the helium coolant leaving the reactor core and as well as reduce the time between nuclear fuel recharges.

Abstract: Ways of increasing massic activity of 188W resulting from irradiation of tungsten targets in the middle flux nuclear reactor IRT-T have been analyzed. Calculation and experimental results of evaluating the influence of blocking effect on accumulation of target radionuclides are presented. The possibility to increase effective activation cross section by creating definite target shape has been experimentally proven.

Abstract: The calculation results of the operating modes of a plasma reactor for utilizing model water-organic compositions based on a closed nuclear fuel cycle’s inflammable wastes in air plasma are shown. Program complex ANSYS Fluent 6.3 with broad data base of gaseous, liquid and solid materials for calculation of different physical and chemical processes was used.

Abstract: In this article process of complex plasma utilization of sludge in low radioactive liquid radioactive waste (LRW) storage pools is investigated. It was also shown the possibility of effective air plasma utilization of such wastes in the form of optimal water-organic compositions with the adiabatic temperature of combustion higher than 1200 °C.

Abstract: Neutron transmutation doped silicon is an important material for electronics that is based on the conversion of ³⁰Si into ³¹P through a ³⁰Si (n,γ) → ³¹Si reaction taking place during the neutron irradiation and followed by the beta decay of ³¹Si into ³¹P. The production of such silicon requires high homogeneity. The paper describes a new facility for NTD of silicon ingots of up to 5 inches in diameter and presents the experimental results that were obtained at IRT-T research nuclear reactor.

Abstract: The article contains an analytical overview of technologies used for obtaining UF₆. The structures of devices for obtaining UF₆ have been considered. Their advantages and drawbacks have been outlined. It has been shown that plasma reactors using uranium tetrafluoride as a raw material are the most efficient in obtaining UF₆.

Abstract: The behavior of the interference absorption coefficient of X-rays in Laue geometry depending upon the disposition of diffraction vector and temperature gradient vector in the perpendicular direction to the reflecting atomic planes family was experimentally studied. The study was carried out for the different thicknesses of quartz single crystal for atomic planes. It was shown that in the case of anti-parallel disposition of the diffraction vector and temperature gradient vector the absorption coefficient of X-rays sharply decreases with the increase of temperature gradient and in the case of the parallel disposition of the diffraction vector and the temperature gradient vector the absorption coefficient firstly increases and then decreases. The theoretical calculation corresponding to the experiment conditions have been done. The physical explanation of the obtained experimental results has been made. The obtained results are in good correspondence with the experiment.