卷 120, 编号 1 (2016)

A method of improving the computational reactor model in the IR program on the basis of the experimental data on the xenon power oscillations is presented. It is concluded on the basis of the deviation of the computed axial offset from experiment that the program requires adjustment. The program was modernized by replacing the dependence of the thermophysical parameters of the core on the specific rate of power release by solving the heat-conduction and heat-and-mass transfer equations. This is accomplished by means of the method and software used in the NOSTRA computer code, which were additionally improved by taking account of the influence of structural changes in the fuel on the thermal conductivity.

This article is concerned with investigations of temperature stratification of the first-loop coolant in the surge line of the pressure compensator in the No. 5 unit of the Novovoronezh NPP. The actual stress-strain state and accumulated structural damage in the surge line in different operating regimes was analyzed by means of multiparametric computational and experimental monitoring. The experimental data demonstrate thermal stratification, giving rise to a temperature differential over the cross section ranging from 30°C under normal operating conditions to 150°C, as a result of disruption of the normal operating conditions, and high thermal stresses. The analysis shows that the cyclic strength of the weld connection of the surge line can be exhausted by the end of the 60-yr life of the No. 5 unit. It is concluded that the actual residual stresses must be measured and calculations of the cyclic strength and the residual life of the surge line must be performed. It is suggested that a technology be developed to strengthen the weld-joint metal in order to reduce the formation of operational surface defects.

Research on the development of EP-450 high-density, Y₂O₃-oxide dispersion-hardened, reactor ferritemartensite steel is described. All available parameters influencing the final density of the compacts were varied in the course of the preparation of the powders and electric-pulse consolidation. The research established that samples with density equal to 99% of the theoretical value can be obtained for the following optimized mechanical activation and electric-pulse consolidation parameters: mechanical alloying time 30 h, optimal Y₂O₃ amount 0.2–0.5 wt.%, sintering temperature 825–890°C, climb rate to the prescribed temperature >300°C/min, load 70–80 MPa, holding time at the load – without isothermal holding or holding for ≥3 min.

It is shown that the thermodynamics characteristics of uranium hexafluoride solutions with volatile hexaand pentafluoride elements are a consequence of the strictly symmetric configuration of their molecular structure in the gaseous and liquid states. Simple methods are proposed for evaluating the properties of binary mixtures of elemental penta- and hexafluorides. These methods are based on a comparison of the element–fluorine bond length in the constituent molecules of system and the known enthalpy of mixing of one solution with the potential energy in the formation of a pair of unlike molecules of a different solution.

A new type of coherent electromagnetic process – coherent bremsstrahlung – on colliding beam setups with short bunches is examined. It is shown that solid-state photomultipliers can be used to detect, register, and investigate coherent bremsstrahlung.

Test results for models of particle coagulation and settling on a surface in an aerosol module in analytical tests and experiments are presented. A module is being developed for modeling the dynamics of polydisperse multicomponent aerosols in the first loop of VVER during a serious accident with emission of fission products from fuel elements into the coolant flow.