Vol 126, No 1 (2019)

The conception of a transportable small power plant based on a high-temperature gas-cooled nuclear reactor and a gas-turbine plant for supplying heat and electricity to settlements in the Far North and Siberia is presented. An open-loop energy conversion scheme with a Brayton cycle making possible quick start-up and leveling the fluctuations due to routine maintenance work or single failure of the main equipment, in the power delivery to the consumer is studied.

The problem of calculating a model of the radiation protection of a monoblock reactor, having a fast neutron spectrum and cooled by a eutectic lead-bismuth alloy, by a combined method using the CADIS methodology is examined. A deterministic calculation of the adjoint problem is performed by the method of characteristics, ensuring the smoothness of the solution. An algorithm for selecting the nodes of the weight window grid is presented for the many-group problem. The results of the neutron flux density distribution for the computational domain are described. A statistical error of 7% is obtained, confirming the methodological reliability of the spatial distribution of the neutron flux density in the Monte Carlo method.

The developmental history of the series-produced core for nuclear icebreakers and its conceptual and structural designs and the computational-methodological base of the physical design are presented. The fundamental differences from VVER-type power reactor cores, which are due to the specific operating conditions of ice breakers, are discussed. Measurements of the basic neutronic characteristics of a series-produced icebreaker core are presented and compared with calculations performed with the tested software system VKN-02. Experimental data confirm that the accuracy of the VKN-02 system in calculating the neutronic characteristics determining nuclear safety and the thermal engineering reliability of an icebreaker core is acceptable.

Some problems arising in the description and generalization of experimental data on the critical heat fluxes appearing upon boiling in channels are due to the lack of a strict definition of the critical heat flux and strict criteria for recording the conditions under which it occurs. It is shown that the desire to reduce the number of variables in the description and generalization of the data often leads to an incorrect interpretation of the influence of individual parameters. The problem of generalizing the experimental data is discussed in connection with the presence of a strong coupling between variables. This connection is what explains the large number and the diversity of empirical relations for the critical heat flux. It is suggested that the problem of multicollinearity should be solved at the stage where the parameters of the regression model are chosen, preference being given to independent variables. Attention is called to the drawbacks of look-up tables, derived by averaging and smoothing the primary experimental data, in describing the critical heat flux.

The results of an investigation of the development of porosity and swelling in the alloys V–Cr, V–W, V–Ta, and V–W–Ta irradiated by 40 keV helium ions to fluence 5·10²⁰m^–2at 650°C are presented. The investigations were conducted by means of transmission electron microscopy along the travel path of ions; this afforded some idea about the total swelling of the samples and the character of the depth distribution of the porosity in the targets. It was found that the gas swelling in binary alloys is identical to within the measurement error. Multicomponent alloying is effective from the standpoint of the suppression of helium swelling – the ternary alloy V–1%W–1%Ta is subjected to significantly less helium swelling. It observed for the first time in experiments that the distribution and penetration depth of helium ions different significantly from the calculations, and the effect depends strongly on the chemical composition of the irradiated alloy. Among the alloying elements tantalum promotes deeper penetration of helium ions. In addition, the effect increases with increasing concentration of tantalum in the alloy: in the alloys V–1%Ta and V–2%Ta, pores were discovered at depth 450–500 and 850–900 nm, respectively, which is significantly greater than the computed travel distance of 48 keV helium ions in vanadium (~300 nm).

Organizational and economic approaches to solving the problems of the reprocessing and disposal of spent nuclear fuel are examined. The capacity shortage for reprocessing spent nuclear fuel is equal to 510–530 tons/yr. It is shown that the financial resources needed to create storage and reprocessing facilities for spent fuel can be obtained by increasing the cost of electricity produced by NPP, which can equal 0.013–0.02 rubles/(kW·h).

A practical example of a hermetic cable gland for nuclear power plants is described. A model is constructed for performing diagnostics of the parameters of the hermetic cable gland and a procedure for performing operational monitoring of its state is developed. The proposed device makes it possible to reduce the development risk of emergency situations in the system by increasing the operational reliability of the hermetic cable gland. For this reason, operation monitoring of the electrodynamic state of a hermetic gland in NPP on the basis of an equivalent model is significant and urgent.