Ecological features of fast reactor nuclear power plants (NPPs) at all stages of their life cycle

The future nuclear power industry should focus on the enhanced safety reactors such as inherently safe liquid metal fast neutron reactors. Many years of the operating experience from the BN-600 fast power reactor show that it has some advantages in terms of safety (the large amount of sodium in the reactor, large boiling point margin, etc). The safety systems have been improved in BN-800 which is under construction and further in BN-1200 project. Along with the design features of nuclear power plants, the overall safety culture including the optimization of radiation protection is very important. The UrFU in conjunction with the Rosatom enterprises works in this direction, dealing with the route optimization of work in radiation fields using dynamic programming techniques, optimization of the composition of the homogeneous protective materials for a given isotopic composition of radioactive contamination, the development of computer models of radioactive systems for training of the dismantling personnel. The management of the increasing amount of radioactive waste (RW) is the priority task of the nuclear power industry. Fast reactors allow it to minimize the amount of RW through the extraction of the fission products from the irradiated nuclear fuel while uranium and plutonium are returned to the reactor at a closed nuclear fuel cycle. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Route optimization in the removal of radiation hazards

Route optimization is one of the types of jobs peculiar to nuclear facilities. For example, route optimization can be used as a way to minimize the radiation dose to personnel during the dismantling of dangerous radiation equipment. The sequence of jobs affects the total dose exposure of personnel. Also, in the solution of problems there are additional constraints in the form of precedence conditions. These conditions are due to technological constraints on the sequence of dismantling. This problem is similar to the well-known traveling salesman problem, but unlike the classic traveling salesman problem, the cost function depends on the list of outstanding tasks. A version of the method of dynamic programming has been designed to solve this problem and the appropriate software has been created. The developed software to provide estimates reduces personnel exposure in the optimization sequence of dismantling radioactive equipment. © 2014 WIT Press.International Journal of Safety and Security Engineering;International Journal of Sustainable Development and Planning;WIT Transactions on Ecology and the Environmen

Warped Riemannian metrics for location-scale models

The present paper shows that warped Riemannian metrics, a class of Riemannian metrics which play a prominent role in Riemannian geometry, are also of fundamental importance in information geometry. Precisely, the paper features a new theorem, which states that the Rao-Fisher information metric of any location-scale model, defined on a Riemannian manifold, is a warped Riemannian metric, whenever this model is invariant under the action of some Lie group. This theorem is a valuable tool in finding the expression of the Rao-Fisher information metric of location-scale models defined on high-dimensional Riemannian manifolds. Indeed, a warped Riemannian metric is fully determined by only two functions of a single variable, irrespective of the dimension of the underlying Riemannian manifold. Starting from this theorem, several original contributions are made. The expression of the Rao-Fisher information metric of the Riemannian Gaussian model is provided, for the first time in the literature. A generalised definition of the Mahalanobis distance is introduced, which is applicable to any location-scale model defined on a Riemannian manifold. The solution of the geodesic equation is obtained, for any Rao-Fisher information metric defined in terms of warped Riemannian metrics. Finally, using a mixture of analytical and numerical computations, it is shown that the parameter space of the von Mises-Fisher model of $n$-dimensional directional data, when equipped with its Rao-Fisher information metric, becomes a Hadamard manifold, a simply-connected complete Riemannian manifold of negative sectional curvature, for $n = 2,\ldots,8$. Hopefully, in upcoming work, this will be proved for any value of $n$.Comment: first version, before submissio

Evolutionary stage of the spectral variable BD+48 1220=IRAS 05040+4820

Based on high-resolution observations (R=60000 and 75000), we have studied the optical spectral variability of the star BD+48 1220 (IRAS05040+4820). We have measured the equivalent widths of numerous absorption lines of neutral atoms and ions at wavelengths from 4500 to 6760 AA, as well as the corresponding radial velocities. We use model atmospheres to determine Teff=7900K, log g=0.0, microturbulence velocity xi_t=6.0, and the abundances for 16 elements. The star's metallicity differs little from the solar value: [Fe/H]=-0.10 dex. The main peculiarity of the chemical composition of the star is a large He-excess, derived from the HeI 5876 A absorption, [He/H]=+1.04, and the equally large O-excess, [O/Fe]=+0.72 dex. The C-excess is small, [C/Fe]=+0.09 dex, and the ratio [C/O]$\le$ 1. We obtained a revised relation for the light-metal abundances: [Na/Fe]=+0.87 with [Mg/Fe]=-0.31. The barium abundance is low, [Ba/Fe]=-0.84. The radial velocity of the star measured from photospheric absorption lines over three years of observations varies in the interval V_sun = -(7 - 15) km/s. Time variable differential line shifts have been revealed. The entire set of available data (the luminosity Mv~-5m, velocity V_lsr~-20 km/s, metallicity [Fe/H]=-0.10, and peculiarities of the optical spectrum and chemical composition) confirms the status of BD+48 1220 as a post-AGB star with He- and O-excesses belonging to the Galactic disk.Comment: 42 pages, 7 figures, 6 tables, accepted by Astronomy Report

Interaction effects and phase relaxation in disordered systems

This paper is intended to demonstrate that there is no need to revise the existing theory of the transport properties of disordered conductors in the so-called weak localization regime. In particular, we demonstrate explicitly that recent attempts to justify theoretically that the dephasing rate (extracted from the magnetoresistance) remains finite at zero temperature are based on the profoundly incorrect calculation. This demonstration is based on a straightforward evaluation of the effect of the electron-electron interaction on the weak localization correction to the conductivity of disordered metals. Using well-controlled perturbation theory with the inverse conductance $g$ as the small parameter, we show that this effect consists of two contributions. First contribution comes from the processes with energy transfer smaller than the temperature. This contribution is responsible for setting the energy scale for the magnetoresistance. The second contribution originates from the virtual processes with energy transfer larger than the temperature. It is shown that the latter processes have nothing to do with the dephasing, but rather manifest the second order (in $1/g$) correction to the conductance. This correction is calculated for the first time. The paper also contains a brief review of the existing experiments on the dephasing of electrons in disordered conductors and an extended qualitative discussion of the quantum corrections to the conductivity and to the density of electronic states in the weak localization regime.Comment: 34 pages, 13 .eps figure

The photometric and spectral investigation of CI Camelopardalis, an X-ray transient and B[e] star

We combined the results of UBVR photometry of CI Cam taken at Sternberg Astronomical Institute in 1998--2001, and moderate resolution spectroscopy taken at Special Astrophysical Observatory during the same time period. Photometry as well as fluxes of Balmer emissions and of some Fe II emission lines of CI Cam in quiet state reveal a cyclic variation with the period of $1100\pm50^d$. The variation like this may be due to an orbital motion in a wide pair with a giant star companion that exhibits the reflection effect on its side faced to a compact companion. The V-band photometry also confirms the pre-outburst 11.7 day period found by Miroshnichenko earlier, but with a lower amplitude of 3 per cent. The possibility of identity of this photometric period with the period of jet's rotation in the VLA radio map of the object CI Cam was investigated. The radio map modelling reveals the inclination of the jet rotation axis to the line of sight, $i = 35-40^o$, the angle between the rotation axis and the direction of ejection of the jet, $\theta = 7-10^o$, and jet's spatial velocity of 0.23--0.26c. Equivalent widths and fluxes of various spectral lines show different amplitudes of changes during the outburst, and essentially distinct behaviour in quiescence. Five types of such behaviour were revealed, that indicates the strong stratification of a gas and dust envelope round the system . The time lag of strengthening of 50--250$^d$ in the forbidden line of nitrogen [N II] was found relatively to the X-ray outburst maximum.Comment: 15 pages, 8 figures, 3 tables, Astron. Zh., 2002, (in press), vol.79, number