Abstract: An approach to solving the three-dimensional transport equation is described. Directional probabilities, which make it possible to analyze axial leakage numerically, are defined. The problems of modeling the boundary conditions for the neutron flux under ordinary operating conditions of reactors and under the conditions of dewatering are discussed. The results obtained show that if the effect of the spectrum of the two-dimensional problem of a VVER cell is taken into account, then the axial leakage changes, especially near the reflector. The axial leakage also increases if the cell contains dewatered channels, but only if the boundary conditions are modeled in the form of mirror reflection on a real hexahedral boundary. This effect vanishes if the equivalent cylindrical cell approximation is used and the boundary conditions are modeled in the form of isotropic reflection. PubDate: 2016-07-01

Abstract: This is article is concerned with finding ways to improve the technical and economic characteristics of desalination plants. The possibility of using a contact heat-exchanger to evaporate part of the saline water flow by means of vapor circulating in the heat-exchange loop is examined. Technical solutions with high economic characteristics of desalination, absence of salt deposits on the working surfaces of the plant, design simplicity, and the possibility of automating dynamic processes and maintaining the operating regime are shown. PubDate: 2016-06-30

Abstract: An exact relation expressing the difference current and the derivative of the scalar neutron fl ux via a coeffi cient of proportionality is obtained. This relation is defined as the kinetic Fick’s law. It is shown that Fick’s law in the elementary theory of diffusion is a particular case of the kinetic law. The conventional criterion of the diffusion approximation is supplemented by a condition that expands the range of application of the diffusion approximation. The conceptual scheme of a method termed the integral-differential method of solving the transport equation on the basis of the kinetic Fick’s law is presented. PubDate: 2016-06-30

Abstract: The concentration of neutron radiation far from a source is discussed. A new method is proposed for solving this problem by choosing from among the scattered neutrons the ones that have acquired the required direction of flight and energy. The material along which such a neutron will travel must possess a small neutron cross section at the given energy. Materials consisting of isotopes with a large resonance cross section, for example, 56Fe, meet the requirements. The method discussed for concentrating high-energy neutrons makes it possible to increase their concentration more than 1000-fold in the detection area far from the source compared with isotropic propagation away from the source in all directions with equal probability. PubDate: 2016-06-30

Abstract: The results of investigations of swelling and in-reactor creep of the ferrite-martensite class steels EP-450, EP-823, and EI-852 irradiated in a BN-350 reactor at 305–700°C to damaging dose in the range 20–89 dpa are presented. The characteristics of radiation creep of three of the ferrite-martensite steels are close despite the differences of the chemical composition and heat-treatment. The relation B = 4.864·10–2 + 1.45·10–3T describes the average modulus of radiation creep of the experimental steel in the interval 305–550°C. PubDate: 2016-06-30

Abstract: The impact of research building B at the Bochvar All-Russia Research Institute for Inorganic Materials (VNIINM) on the subsoil (geological medium) is evaluated. It is shown that there is no radioactive contamination of the soils or underground water. The test results are used to substantiate the radiation safety of decommissioning the building. The network of observational wells that was created as part of engineering and environmental research is intended for monitoring the status of the underground water at the site of VNIINM during and after the decommissioning period for building B. PubDate: 2016-06-29

Abstract: The equations of a heterogeneous reactor with effective conditions at the core boundary and end reflectors are derived. The numerical solution of these equations gives significant reduction of the axial harmonics and the computational time for calculation of reactors with a large spike in the thermal neutron flux in the end reflectors. The efficacy of the method is illustrated by an example of a calculation of a reactor with an intermediate neutron spectrum. PubDate: 2016-06-29

Abstract: The aim of the investigations was to analyze the character and depth of the corrosion damage to EK-164 steel irradiated in contact with uranium dioxide at temperature 410–640°C, maximum damaging dose 66–94 dpa, and burnup 10–13% h.a. These investigations were performed by means of full-scale electropotential scanning of irradiated elements as well as optical and scanning electron microscopy of the selected segments. Fuel-side intercrystallite corrosion of the steel at depth to 55 μm was found at 450°C. At irradiation temperature 580°C in the presence of corrosive fission products, the damage acquired a mixed character involving continuous and intercrystallite corrosion to depth reaching 60 μm. At intermediate temperature and maximum damaging dose, the corrosion depth in steel does not exceed 20 μm. PubDate: 2016-06-29

Abstract: The radiation status of the special ventilation and piping systems is investigated as part of the work on the preparation of building B at the Bochvar All-Russia Research Institute for Inorganic Materials for decommissioning. Methods for extracting samples have been developed. Analysis for the content of plutonium isotopes showed that the deposits and precipitates are medium-level wastes. PubDate: 2016-06-27

Abstract: The mathematical modeling of nuclear fuel burnup is based on the solution of a system of ordinary differential equations of the Bateman type. The particularities of the systems obtained are examined. Examples of possible computational inaccuracies of the ORIGEN2 code are presented. New approaches to the solution of isotopic kinetics problems with a complete basis of elements in the fission product yield, including short-lived elements, are examined. PubDate: 2016-06-27

Abstract: Methods for trapping the 14C in waste gases by means of a combined technology are examined. The wastes gases from pyrochemical production can be purified by removing 14C by passing the gases at rates to 5 m3/h through a 0.5 m high layer of Ba(OH)2·8H2O granules in a 0.14 m in diameter apparatus after dilution with atmospheric air. The purification of the waste gases from hydrometallurgical production by removal of 14C (50 m3/h) is best accomplished by passage through a 0.28 m in diameter packed tower with 2.7–4 m high packing irrigated by an alkali solution which is regenerated by means of calcium hydroxide. The waste gases from pyrochemical production can also be passed through a packed tower. In this case the 14C is fixed in insoluble calcium carbonate and is placed in a storage facility and subsequently buried. The proposed technologies make it possible to purify the waste gases formed during the reprocessing of spent uraniumplutonium nitride nuclear fuel in a reprocessing module used in an on-site nuclear fuel cycle by removing 14C to a level admissible for air in production enclosures. PubDate: 2016-06-27

Abstract: The parameters of the neutron flux in the experimental channels of VVR-Ts are determined. It is shown that to evaluate the 99Mo yield it is necessary to take account of, aside from the neutron flux, the dependence of the fission cross section of 235U on the temperature of the neutron gas. The blocking coefficient is calculated for an experimental uranium target. The computed radiochemical yield of 99Mo is compared with the experimentally measured value. It is shown that the average yield equals 0.75. A correlation is found between the neutron flux density, which is directly proportional to the power of the VVR-Ts nuclear reactor, at the target location and the radiochemical yield of 99Mo. PubDate: 2016-06-27

Abstract: The effect of the fume gases, produced when the insulation of chlorine-free cables burns, on the catalytic activity of hydrophobic low-temperature and hydrophilic high-temperature platinum catalysts of hydrogen oxidation, which are to be used in the ventilation-gas detritization system. The temperature regime for the combustion of cables in the presence of an oxygen deficiency is determined and the semiquantitative composition of the products formed is obtained. Upon exposure to the fume gas flow at room temperature the experimental samples of the catalysts were almost completely poisoned. At the initial temperature 473 K of a hydrophilic catalyst thermal activation of the catalyst occurs in the presence of fume gases. PubDate: 2016-06-01

Abstract: This work is devoted to the development of a method for solving the Boltzmann kinetic equation for neutron transport. The method is focused on solving an integral equation for neutron transport in a reactor cell with a complex geometry and different boundary conditions. An algorithm is proposed for solving the problem taking account of anisotropic scattering in the linear-anisotropic approximation. The approach is based on expanding the neutron flux in a system of orthogonal two-dimensional polynomials in each uniform zone of a heterogeneous cell. This expansion reduces the system of linear integral equations to a system of linear algebraic equations. The relations required to calculate the coefficients in the equations (six-fold integrals) as well as the computational algorithm are presented. Calculations of cylindrical and cluster cells are presented. The calculations are compared with the surface pseudosource method. It is shown that the results have advantages over the method of first collisions probabilities. PubDate: 2016-06-01

Abstract: Research based on the pulsed neutron experiment method (α-method) of subcriticality monitoring of the spent fuel pool at the Smolensk NPP is presented. The procedure includes stationary and nonstationary neutron-physical calculations and measurements of the main characteristics of a subcritical multiplying system, which the spent-fuel pool is. A description of the STEPAN-KhOYaT software specially developed for the computational support of the pulsed experiment is given. The subcriticality for real loads of spent-fuel pools is calculated and measured using the procedure. PubDate: 2016-06-01

Abstract: A scheme for trapping the nitrogen oxides released during operations with liquids in radiochemical technologies is develop-ed: the outgoing gases containing nitrogen oxides pass through a dephlegmator (in the process of dissolution of fuel or wastes) or bubbler condenser (in the process of denitration and vitrification), through FSGO and FARTOS filters after water aerosols are introduced into them, and through the RFTBL and then SMOG apparatus after the next water-aerosol portion is introduced. The proposed solution is incorporated in the technological schemes of the spent nuclear fuel reprocessing module in the on-site nuclear fuel cycle of the BREST reactor. PubDate: 2016-06-01

Abstract: This article contains information on professional external and internal radiation exposure in 2013 of workers in organizations, including NPP, on territories serviced by the Federal Medical-Biological Agency of Russia (FMBA). The parameters of the dose distribution are calculated: mode, median, average, standard deviation, quantile, and coeffi cient of variation for institutions on territories serviced by the FMBA. The number of individuals subject to individual dosimetric monitoring, grouped by institution and taking account of the radiation exposure dose is analyzed. Information on the professional external and internal radiation exposure of NPP workers is presented. PubDate: 2016-06-01

Abstract: A method is developed for solving the many-group neutron transport equation with an anisotropic scattering cross section in cylindrical geometry by a method where the operator is split and the single-group spatialangular parts of the problem are solved by the method of surface pseudosources. The developed procedure is implemented in the RATsIYa option of the WIMS-SH and SVL software systems. It is used to solve a VVER-1000 cell with mixed uranium-plutonium fuel and a VVER-1000 supercell with an absorbing element. The factor K
∞
calculated in the transport and linear-anisotropic approximation differs by up to 0.4% in the first cell and up to 2.3% in the second cell. PubDate: 2016-06-01

Abstract: The two-dimensional thermohydraulic model used in the thermohydraulic module of the SOKRAT-BN code is described and the computational results obtained by using it are presented. The thermohydraulic model is based on the solution of two-dimensional equations using empirical correlations for determining the intensity of the turbulent transfer of mass, energy and momentum in the radial direction. The experiments performed in the 19- and 37-pin assemblies on the Siena stand in Japan and in the 37-pin assembly in the KNS stand in Germany were calculated. The average deviations of the computed values do not exceed 10%. PubDate: 2016-06-01

Abstract: The conditions for using the SMA method based on foreign databases on seismic classification are examined. In contrast to the initial SMA methodology a modified approach does not presume rejection of computationalexperimental evaluation of seismic safety under real conditions. However, the methodology presented examines the possibility of validated reduction of work, including rejection of computational-experimental checking when using the domestic database now under development. Evaluations of the seismic safety margin are used in the validation of service life extension for NPP, reexamination of safety, and probability analysis of safety as well as in establishing the technical specifications for equipment, modernization and reconstruction, and improving safety. PubDate: 2016-06-01