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Currently, there is an intensive development of manned and unmanned submersibles due to development of offshore oil and gas fields, development of underwater archaeology and exploration activities in transit zones regarding seabed mineral extraction. The depth of immersion and the nature of the underwater technical works performed determine not only the design of the underwater vehicle, its power-to-weight ratio and technical equipment, but also impose high requirements on reliability, survivability, and habitability, if the underwater vehicle implies that the operator is on board inside a pressure hull. The main objectives of the study carried out by the authors were to achieve high reliability and survivability of the main elements of the propulsion-steering complex, which ensure movement of a human-occupied vehicle in the water column, its positioning and retention at a given point in the water area.For this purpose, it was proceeded to development of an automated control system for the electric drive of the propulsive device of manned immersible. The proposed developments include a flowchart of the movement control system, circuitry engineering solutions using power semiconductor devices to maintain operability of the electric drive in extreme and emergency operating conditions, and movement control algorithms. Electromagnetic calculations of the active part of the electric machine were performed by the finite element method, considering the geometric features of the dental zone of the rotor and stator. The proposed mathematical apparatus served to calculate optimal control actions of the electric drive and to quantitatively assess the reduction in electrical losses once optimal control was applied. The calculation of the optimal control parameters was carried out using the maximum principle. The initial conditions for auxiliary functions are determined by the Newton‒ Raphson method. A comparison of various modes of operation of the electric drive was made regarding their influence on duration of the campaign, and other parameters.The calculations did not consider the parameters and geometry of the propulsive device (the propeller) since the developers of electric propulsion systems for manned and unmanned underwater vehicles of various classes often deliberately reduce the efficiency of the propeller to increase speed of the electric motor shaft, resulting in a decrease in the dimensions and weight of the latter.

In this paper, we consider means to develop and improve a dc traction power supply systems and its adaptation for high-speed mine lines. One way to improve and increase the efficiency of the traction power supply system is to increase the rated voltage in the dc traction grid up to 24 kV. This allows increasing the throughput and carrying capacity of railways, increasing the distance between substations, and reducing the cross section of the traction grid wires and electricity losses in power supply devices. All this, as well as the absence of supply voltage unbalance under dc, inductive losses, and a significantly lower electromagnetic effect on the infrastructure, is more efficient than all ac traction power supply systems. We determined the directions of numerical modeling and proposed nonlinear numerical models that allow analyzing the interaction of sources of electromagnetic fields of traditional and superconducting electrical equipment under the conditions of an unlimited region of magnetic field propagation and the absence of symmetry of the field distribution in space. To determine the effect of electromagnetic fields on the integral parameters of traditional and superconducting electrical equipment, an algorithm and a package of applied programs were developed. We performed studies and substantiated the parameters and dimensions of superconducting inductive reactors of smoothing traction substation filters at which the volume of occupied space is minimized and the best use of superconducting material is ensured at a specified energy intensity.

The technical and economic indicators of introduction of new type of smoothing reactors are calculated considering the features of the operating conditions of traction power supply systems of direct current 3,5 kV. Based on the data provided by operating and installation organizations, an assessment was made of cost indicators of catenary system repairs.The main financial items were formed, on the basis of which the calculation of net income and net present value was carried out in order to determine the payback period of inv estment costs.The payback period based on the calculations (a little more than three years for equipment related to fixed assets with an assigned service life of twenty-five years) indicates a high level of investment attractiveness of a new type of smoothing reactor. The suggested method allows calculations using a large number of physical and operational parameters that affect the economic performance of the device.

—Two units of an RZhFA-6500 reactor were put into operation into a current return circuit of the Uglerod traction substation of the West Siberian Railroad in series connection with RBFA-U-6500/3250 reactor as a part of a resonant-aperiodic L-shaped filter device. Before assembling the new type reactor, its inductances were measured with the ammeter–voltmeter method under alternating current. The phase-shift angle between current and voltage drop on the RZhFA-6500 reactor was not controlled. To check the operability of the new of type reactor and analyze its efficiency, a series of experiments in the regular and emergency operation modes of the dc traction power supply system were conducted. An experiment using a forced short circuit without cessation of the motion of electric vehicle over the section was performed. Oscillograms at the catenary feeder and the circuit of traction current return were synchronously recorded upon disconnection of a high-speed switch. A comparative analysis of harmonic composition of the voltage drops on the reactors of two types was carried out. The amplitude–frequency responses of traction current for different operation modes of the Uglerod traction substation were plotted. The method for calculation of the RZhFA-6500 reactor inductance based on recorded oscillograms in regular and emergency operation modes of the traction power supply system was developed and tested. A universal formula for inductance calculation taking into account the phase-shift angle between the current and the voltage drop on the reactor when measurements by the ammeter–voltmeter method was derived.

The use of advanced structural concepts for development of electric power equipment of dc traction power supply systems allows one to triple the power density per unit volume. An armored rod radial–cylindrical magnetic system with massive nonlaminated design elements, which is split into sections by nonmagnetic gaps, allows one to provide high mechanical strength without using additional fasteners and pressing elements. This design also provides an admissible level of hysteresis and eddy current losses, as well as meeting the requirements for unconditional linearization of a magnetic flux in the range of working currents. The latter is caused by the performance of smoothing reactors as parts of high-power rectifiers that feed rolling stock.

Two blocks were commissioned of an RZhFA-6500 reactor as part of the two-link smoothing device at the Letnaya traction substation of the Sverdlovsk Railroad. To test the efficiency of the reactor, a forced short circuit experiment was performed without stopping the movement of the electric vehicle over the section, the level of psophometric voltage on the dc buses of the traction substation was measured and an experiment was carried out of a forced short circuit with cessation of movement over the section. During the experiments, oscillograms of transient processes were taken, analysis of which confirmed the efficiency of the new type of reactor in the structure of a two-link filter device.

Utilization of DC and AC HTS cable lines in electrical grid enables enhancement of the transmission capacity, reduced power losses, lowering of allotment areas, improvement of environmental conditions and improvement of fire and explosion safety of these power transmission lines. An HTS DC cable lines (CL) bring the new additional advantages, including the opportunity to introduce into the power system a new electric link without increasing fault current level. It allows to connect input stations in the city on medium voltage sites and, as a result, improves the reliability of the energy supply to customers. Federal Grid Company of Unified Energy System (FGC UES) started with the development and construction of a HTS DC cable link, which included the cable, cryogenics, AC/DC/AC converters, terminations and cable coupling joints. The link will connect two substations on downtown area. The purpose of this project is to operate at 50 MW HTS cable in the live network of St. Petersburg to demonstrate its effectiveness and improve the reliability of the grid. Nowadays are developed all the elements of the line and all technologies required for cable manufacturing. After successful tests of two 30-m HTS cable samples together with current leads and coupling boxes, full scale production of all devises for HTS DC cable line was began. This paper describes the current status of the production and tests of the HTS cable line elements.

The design of the ASTRA facility and critical assemblies that simulate physics features of modular high-temperature reactors (HTHR-Ms) with a graphite moderator and reflectors loaded with fuel particles having multilayer ceramic coatings is described in detail. Geometrical dimensions of the main elements and regions of the critical assemblies, composition of the materials used, and experimental results for various configurations of the critical assemblies are presented. A detailed computational benchmark model allowing for the structural and compositional features of the critical assembly configurations in question is developed on the basis of all the above data. The results are to be used for verification of the neutronics codes used for calculations of high-temperature helium-cooled reactors.

The results of a search for the optimal water-uranium ratio for VVER with no changes to the fuel elements and assemblies are presented. It is shown that decreasing the volume of a fuel pellet while maintaining the same 235 U load as a result of increasing the enrichment will decrease the specific consumption of uranium and increase the run time. The proposed modifications to the fuel can be implemented in operating reactors and advanced VVER designs.

The “zero” power ASTRA critical facility at the Kurchatov Institute is intended for experimental investigation of neutronics of HTGR reactors. Spherical graphite elements with multilayer coated fuel particles inside, along with pure graphite and absorber containing spherical elements can be used in different configurations of cores. Reactor-grade graphite blocks are used in the structures of bottom, side, top, and/or internal reflectors. Hardware capabilities of the facility allow creation of the critical assemblies with the outer diameter and height of the side reflector of up to 3.8 and 4.6 m, respectively. The ASTRA critical facility was used to simulate the HTGR reactors earlier designed in Russia, PBMR reactor (being developed in RSA) and is going to be used under the international GT-MHR project (France, Japan, Russia, USA) mainly for the purpose of obtaining experimental benchmark data for computer code validations. Brief description of the ASTRA facility characteristics, investigated core configurations, experimental methods, and results is given in the paper.

The TOPAZ‐2 reactor system is a heterogeneous epithermal system fueled with highly‐enriched fuel based on uranium oxide, cooled by a sodium‐potassium liquid metal (NaK), using a zirconium hydride moderator, with 37 thermionic fuel elements (TFEs) built into the core. The core is surrounded by a radial beryllium reflector which contains rotating regulating drums with moderating segments. An important problem is the guaranteeing of nuclear safety upon the accidental falling of the TOPAZ‐2 reactor into water, which leads to the growth of the reactivity of the reactor. It has turned out that it is necessary to use the Monte‐Carlo method for the conduct of neutronics calculations of such a complex reactor. In the United States (U.S.) and Russia, different codes based on the Monte‐Carlo method are used for calculations — the MCNP code in the U.S., and the MCU‐2 code in Russia. The goal of this work is the comparison of the codes and neutronics data used in the U.S. and Russia for the basis of the TOPAZ‐2 nuclea...