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Vol 122, No 4 (2017)
- Year: 2017
- Articles: 10
- URL: https://journal-vniispk.ru/1063-4258/issue/view/15507
Articles
Neutron-Physical Model Impact on the Calculation of a Serious Accident with Sodium Boiling in a Fast Reactor
Abstract
A comparative analysis is made of calculations of a loss-of-coolant accident in a 1500 MW(t) fast reactor. The COREMELT code with different neutron-physical modules RADAR3D and RAKAR2D and the same thermohydraulic module COREMELT are used. The computational results are used as a basis for comparing the self-protection of a reactor with a sodium cavity at the top of the core for the case of a serious accident with coolant boiling. The effect of the diffusion and transport modules of the spatial neutron-physics models on the calculation is analyzed.
217-225
Article
Measurement of the Power Coefficient of Reactivity of VVR-Ts in a Wide Power Range
Abstract
The power coefficient of reactivity of VVR-Ts was previously determined only in the range 10–11 MW. The aim of the present work was to determine the power coefficient of reactivity in the range 1–10 MW. The experiment was performed on a completely depoisoned reactor. The change in the reactivity excess was determined according to the position of the control rods. It was shown experimentally that the power coefficient of reactivity is not constant and is negative for the given power range. Thus, the VVR-Ts reactor can operate safely in different operating regimes.
226-229
Heat Transfer in Turbulent Flow. Part 2. Velocity and Temperature Distributions
Abstract
Relations describing the velocity and temperature distributions are studied on the basis of an analysis of a large amount of experimental data from investigations of temperature fields in turbulent flow of different media – air, water (P ≥ 1) and liquid metal (Pr << 1). It is noted that the use of the coefficients νt and at of turbulent transfer of momentum and heat, respectively, as well as their ratio – the Prandtl number – for the calculation of the heat transfer intensity can lead to significant errors, though in so doing an apparent correspondence is observed between the experimental and computations data expressed in logarithmic coordinates in the form Nu = ƒ(Re) or Nu = ƒ(Pr), Nu = ƒ(Pe). It is concluded that in engineering calculations of heat transfer in turbulent flow it is preferable to use relations based on the velocity and temperature distributions at Pr = const.
230-242
Magnetic Flowmeter for Fast Sodium Reactors
Abstract
A magnetic flowmeter for liquid sodium is described. The inductor in this device consists of an electromagnet generating a pulsed, low-frequency, magnetic field. The use of a pulsed magnetic field made it possible to separate the informative component of the signal from all electromagnetic interference whose time variation is not a multiple of the frequency of the excitation magnetic field. Thus, all interferences at the industrial frequency and the thermo-emf are eliminated. This increases the accuracy of flow rate measurements significantly and makes it possible to reduce the magnetic field in the channel. The power of the inductor does not exceed 0.5 W. There is no need to adjust the zero point, and it is possible to measure low flow rates and the reverse flow. The physical principles of the method of measurement, the design particulars and technical characteristics of the device, and the results of tests are examined.
243-251
Technology and Facility for Incinerating Irradiated Reactor Graphite
Abstract
The USG-1 facility was developed to incinerate spent reactor graphite. It is equipped with a monitoring and control system; its maximum capacity is 10 kg/h. Trial combustion of a batch of unirradiated graphite was conducted. The tests showed that the units in the facility are serviceable and irradiated reactor graphite can be incinerated directly in an air flow. For a 1.5 kg load of graphite, the burn rate at 900°C was equal to 0.3 kg/h. The burn rate increases with increasing load. The incineration of irradiated graphite bushings of the EI-2 reactor in the USG-1 incinerator was studied at PDC UGR. The completeness of incineration was 95% and the 137Cs catching efficiency was 95%. With modification of the gas purification unit, the USG-1 incinerator can be used to burn irradiated graphite contaminated by traces of nuclear fuel and in monitoring the atmospheric emissions of 14CO2.
252-256
Mobile Systems for Fluoride Reprocessing of Spent Nuclear Fuel
Abstract
Experts at the National Research Center – Kurchatov Institute have proposed compact reprocessing of spent nuclear fuel from the naval fleet as well as NPPs close to the Arctic coast, directly at the site of offloading, on the basis of an innovative, experimentally verified, fluoride-distillation technology. They propose developing a mobile system consisting of a seagoing carrier (vessel with small displacement) or terrestrial carrier (railroad platform) on which is mounted a compact process line consisting of fluorination and purification apparatus as well as auxiliary setups. There are no liquid wastes in the fluoride processes; solid wastes are to be removed, as they are formed, from the mobile system into special sites in waste locations of the Arctic coast for long-term dry storage in concrete containers.
257-262
Purification of Regenerated Uranium Hexafluoride in a Two-Cascade Scheme with <5% 235U Enrichment
Abstract
Two schemes are proposed for purifying regenerated uranium hexafluoride in double cascades. A large flow of native and a small flow of regenerated uranium are fed into the first cascade. One of the external outgoing flows contains low-enrichment uranium with prescribed concentration <5%. The concentration of the second outgoing 235U flow coincides with the regenerated uranium feed concentration. In this flow, corresponding to purified regenerated uranium hexafluoride, the 232,234,236U concentration decreases. The obtained products meet the ASTM C 996–10 specifications for low-enrichment uranium hexafluoride.
263-270
Possibilities of Increasing Logging Efficiency with Simultaneous Analysis of Neutron and Gamma Fields Formed in Oil Wells
Abstract
The increase in the efficacy of studying well saturation in simultaneous analysis of radiation fields by means of pulsed neutron, activation, and spectrometric logging is examined. It is shown that neutron activation logging can in principle be realized in experimental testing of an operating model of apparatus in producing geophysical objects. Technical solutions using neutron well radiators based on sealed accelerator tubes with a laser source of deuterons and magnetic insulation, as a result of a large neutron yield combined with high pulse stability, as well as a thermally stabilized γ spectrometer, are proposed and validated.
271-277
Hot Particles and Radionuclide Transport in Water Media
Abstract
The characteristics of hot particles in the ambient environment are presented: activity, propagation, size, and density as well as contribution to the total activity of contaminants, distribution factor, leach rate, and deposition rate. The differences of suspensions, bottom deposits, and hot particles are shown. The equations governing the transport of radionuclides are formulated for systems, consisting of hot particles and suspensions, in water and bottom deposits. The coefficients in the equations are determined and the possibility of radionuclides being removed from bays by tides is taken into account. Solutions are obtained for the transport equations and the average sizes of the activity spots owing to hot particles and ordinary suspensions are determined. The possibility of transport of hot particles over large distances in a river floodplain is examined. The water circulation rate at which hot particles are carried out of flooded objects is determined.
278-283
Scientific and Technical Communications
Diagnostics Indicators in Monitoring the Technical State of Direct Charge Sensors in Nuclear Reactors
284-289