[en] The effects of the number of steam generating sections repair strategy type and operational limits related to the sodium-water steam generator sectional structure on the reliability of NPPs with fast reactors are investigated. The mathematical model for accounting for the above-mentioned factors in calculations of the reactor structural reliability is suggested. Using this model the dependence of the NPP unit registrated power utilization factor on a sectionalization degree and steam generator repair strategy is investigated. On the basis of the obtained data analysis it is concluded that the use of the reserved sections is an effective mean for improving the plant reliability factors. At that the highest value of the power utilization factor is achieved with one or two reserved sections. As the real steam generator designs always have some power reserves in the case of one section failure the above advantages connected with the section reservation can be realized by increasing the power of operating sections

[en] Different aspects of decreasing the cost of electric power generated at low-power (up to 10-15 MW) NPPs due to exclusion of constant operational personnel and supplying the blocks with maximum factory readiness to construction site, as well as corresponding decrease of mounting works are briefly discussed. 2 refs., 3 figs

[en] This work is aimed at obtaining experimental information on the fuel elements temperature state in the beyond-the-crisis area and at developing the methodology for calculating the heat exchange coefficient. The following area of the mode parameters: pressure - 11.7-16.7 MPa, temperature at the fuel assembly model inlet - 200-285 deg C, mass velocity - 700-1900 kg/(m² · c), is studied. The availability of certain beyond-the-crisis capacity reserve is experimentally proved. The study results showed, that the coolant temperature at the inlet into the fuel assembly model produces the highest effect on the beyond-the-crisis reserve within the studied range of mode parameters. The beyond-the crisis reserve increases with growth of temperature. The methodology for calculating the heat exchange coefficient in the beyond-the-crisis area is developed

[en] Fields of application of nuclear power plants with subboiling, their specific features and problems connected with the plant operation reliability are considered. Problems of calculational and experimental analyses of instability mechanisms characteristic for the plants with subboiling or on the boundary of boiling regime are discussed. Factors determining boundaries of the existence of a widely spread phenomenon of a subboiling coolant instability namely its oscillations during natural circulation in parallel channels are analyzed in details. Program for numerical calculation of interchannel and the whole circuit instability is given

[en] Engineering technique for calculated estimation of scales of vessel depressurization, caused by cyclic intergrowth of the original or generated in the course of operation defects through the wall is presented. Appropriate calculational analysis as applied to the district heating nuclear power plant reactor vessel is conducted. It is shown that a postulated crack has a large reserve by the number of cycles for the development up to the leak occurrence. A large reserve by the number of cycles up to realization of leak-prior-to-destruction criterion allows one to prevent the reactor vessel integrity violation by nondestructive control means available and a small depressurization scale gives grounds for the working through the variants of the considered accident after effect localization without the obligatory application of such a complex and expensive construction as a protective shell

[en] Assuring district heating plant safety has required the use of engineering decisions based on inherent safety features of the reactor and on passive safety systems. It is shown that the ACT-500 reactor plant for DHPs currently under construction in the USSR meets the enhanced safety concept as follows from the quantitative and qualitative assessments

[en] Postulated accident development which can lead to severe damages of the VPBER-600 reactor core are considered

[en] The article deals with the ways of improving the economic efficiency of low-power NPPs designed for remote areas. Capital investments can be reduced significantly due to a maximum simplification of designs and circuits of the power unit, as well as to unit delivery of systems and equipment. A cardinal reduction of operating costs seems to be feasible, given the technical staff will not stay permanently at the power plant and control over NPP operation will be executed from the remote control center. 2 refs

[en] Reasons for hydrodynamic instability in the reactor coolant circuits at a relatively low pressure not exceeding 2.5-3.0 MPa are discussed. Possible methods for stability increase namely: the decrease of the length of separate draft tubes, increase of steam content, decrease of the coolant subheating up to boiling at the core outlet, channel throttling at the outlet, increase of pressure compensator stiffness, increase of parameter non-identity for separate channels are investigated by calculations and experimentally. The conducted investigation shows that strong stabilizing effect on the amplitude of interchannel and mainly general-circuit oscillations is produced by channel non-identity. The system becomes practically stable at non-dentity exceeding 30%. Leaks through the interchannel space also increase stability. Decrease osubheating up to 20 deg C still more stabilizes the system. A conclusion is made on the necessity of optimal combination of the considered stabilizing factors

[en] Peculiarities of creation of the computer-aided design systems (CADS) for water-cooled and moderated nuclear reactors are considered. A system analysis approach to the given CADS development on the basis of subdividing the design information into types (control, numerical, graphic) and subtypes depending on the degree of their effects on the reactor characteristics is described. A method of CADS construction for initial design stages, based on using the local graphs of controlling parameter is proposed. Description of data base and software structure is given