Vol 120, No 2 (2016)

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.

The influence of the parameters of the neutron intensity regulation system on the uncertainty of the neutron field in a critical stationary reactor is investigated. The spectral expansion method is used to obtain by means perturbation theory a relation for the neutron flux density distribution. On the basis of the relations obtained an expression for the correlation function of the neutron field is obtained and analyzed. Numerical modeling is used to determine the spatial distribution of the dispersion of the neutron field for different arrangements of the neutron detectors and control organs.

The thermal power of NPP with VVER-100 can be increased by increasing the flow of reactor water by increasing the number of revolutions of the main circulation pump. The computational method proposed in the present article makes it possible to determine, for prescribed relations between the reactor water flow and the crisis of heat exchange in the reactor setup with known geometry of flow over the fuel elements and with the prescribed heightened coolant flow, the admissible power increment for constant safety margin of the heat-engineering reliability of the core. The expected effects and problems in implementing the method of operating the reactor are examined and evaluated.

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.

The physical and chemical properties of N₂O and methods for its trapping and decomposition are examined. It is found that organic solvents, water, hydrazine hydrate, and a solution of potassium bichromate in sulfuric acid dissolve N₂O but its stabilization by this method is unreliable. Catalytic decomposition upon heating is acknowledged to be an effective method of neutralizing N₂O. Different composite materials, including those containing d and ƒ elements, were studied as catalysts. It was found that suitable composites for catalytic decomposition of N₂O are SiO₂–Cu, Al₂O₃–Ni at 150°C and Al₂O₃–Cu, Al₂O₃–Fe, Al₂O₃–Ni, and SiO₂–Cu at 250°C. It was shown that the passage of ethanol vapors above the composites at the indicated temperature increases the degree of decomposition of N₂O by a factor of 10. The results obtained were used to develop a gas-purification system in the technology for reprocessing spent nitride fuel.

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.