Vol 124, No 3 (2018)

The approaches used in the SAFR/V1 module modeling the thermal destruction of fuel pins in fast reactors for calculating in integrated code EVKLID/V2 the melting of fuel pins and solidification of the formed melt are described. The enthalpy formulation of the heat-conduction equation is used. The numerical scheme used for the heat-conduction equation in performing the calculations is presented. The realized boundary conditions as well as a model of the gas gap in a fuel pin are described. The module’s capability of modeling heat propagation, including in the presence of a phase transition, is verified on the basis of analytical tests.

A brief historical review of the use of liquid metals in nuclear power in the period 1950–2017 and the state of the problem today will make it possible to evaluate the prospects for their use in the first half of the 21st century (to 2050). There is hope that a discussion of these assessments will stimulate new approaches to the development of nuclear power. This presentation does not make predictions and concerns personal assessments by someone who has worked with liquid metals for more than 50 years. The present article is a revised variant of a preprint and report with the same title made at the interdepartmental seminar “Teplofizika-2007. Heat-and-Mass Transfer and Properties of Liquid Metals.”

Studies are presented of helium porosity in EP-450 oxide-dispersion-hardened yttrium steel, obtained by electopulse sintering, as a function of the Y₂O₃ content in comparison with EP-450 matrix steel and dispersion-hardened steel fabricated by hot extrusion. It is found that multiple zones with different types of helium porosity and different zone distribution develop in steel with 1 wt.% Y₂O₃; in steel with 0.3 wt.% Y₂O₃, there are fewer such zones than in matrix steel and steel obtained by hot extrusion. It is proposed that the extremely nonuniform distribution of porosity over volume and size in steel fabricated by electropulse sintering is associated with the initially strongly defective structure, including residual porosity, as well as with the chromium redistribution between ferrite grains and tempered-martensite grains during the sample preparation process.

A methodological provision system for neutron measurements performed using neutronic setups is described. The metrological characteristics of standard sources of neutrons of five different groups, created based on nuclear reactors and 14 MeV neutron generators, are presented. The neutron spectra are calculated by a standard method and presented in a unified analytical form as a superposition of physically validated spectra.

The possibility of using a rotating magnetic field in a low-frequency direct-flow plasma centrifuge for separating spent nuclear fuel is studied. Estimates of the separative effect in a model binary mixture with atomic mass 120 and 240 were made for concrete values of the parameters of the setup and the properties of rf-discharge plasma. The hydrodynamic parameters of the rotating and expanding plasma column, the separative effect, and the capacity of the setup are obtained.

To ensure that technological installations using radionuclide sources of radiation operate at top efficiency, the effect of the irradiation system parameters on the radiation utilization factor was studied. It was found that the radiation utilization factor depends not on individual parameters of the irradiation system but rather on a certain combination of these parameters. A dimensionless criterion was determined on the basis of these investigations – a complex based on a set of parameters of installations with maximum radiation utilization factor. The radiation utilization factor was determined as a function of the irradiator–irradiated object distance. The numerical range of the criterion corresponding to the maximum radiation utilization factor is shown. Data by means of Monte Carlo calculations were selected by performing experimental studies using independent dosimetric systems.