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The paper presents the results of validating the severe accident block of the EVKLID/V2 integral code used to calculate the processes of fission product release from the oxide fuel melt and dissociation of nitride fuel observed during the destruction of the core in a fast neutron reactor with liquid metal cooling. Based on the obtained results, the uncertainty of calculating individual parameters, including the fraction of released fission products and the loss of the fuel mass during dissociation, is presented. [ABSTRACT FROM AUTHOR]

A tandem electrostatic accelerator with an original design called a Vacuum Insulated Tandem Accelerator was proposed and developed at the Budker Institute of Nuclear Physics. Unlike conventional tandem accelerators, it does not use accelerating tubes—the high-voltage and intermediate electrodes are made in the form of nested cylinders and are fixed at a single feedthrough insulator. This design of the electrodes made it possible to provide a high rate of ion acceleration (up to 25 kV/cm). The accelerator is equipped with a set of diagnostic tools that provide the long-term stable production of a beam of protons or deuterons with an energy varying from 0.6 to 2.3 MeV and with a current varying from 0.1 to 10 mA. The ion beam is characterized by high monochromaticity, energy stability (0.1%), and high current stability (0.4%). The accelerator is used for in situ observations of the blistering of a metal irradiated with protons; for measuring the cross section of the reactions 7Li(p,p'γ)7Li, 7Li(p,α)α, and 11B(p,α)αα; for developing boron neutron capture therapy for malignant tumors by using neutrons generated in the 7Li(p,n)7Li reaction; for the radiation testing of promising materials using fast neutrons in the 7Li(d,n) reaction; and for other applications. The accelerator became an integral part of the medical neutron source for boron neutron capture therapy: the first facility was put into operation in one of the first six BNCT clinics in the world in Xiamen, China; the next two facilities are being made for the National Center of Oncological Hadron Therapy in Pavia (Italy) and for the Blokhin National Medical Research Center of Oncology in Moscow. In this paper, the design of the accelerator and its features and parameters, as well as the results of studies carried out using the accelerator, are presented and discussed. [ABSTRACT FROM AUTHOR]

Models of physicochemical processes in a lead coolant, which can be used as part of the CFD code to justify the coolant technology, and as part of an integral code to describe the state of the reactor plant at the time of the start of the simulated dynamic regime are presented. The described models are integrated into the OXID module of the EUCLID/V2 integral code developed at the Institute for Problems of Safe Development of Nuclear Power Engineering, Russian Academy of Sciences. The OXID module makes it possible to calculate, on the basis of a two-layer model, the growth of an oxide film in a lead coolant on the surface of a metal that is in contact with liquid lead, the crystallization of dissolved oxides on the channel walls, the formation of lead oxide particles (nucleation) in a coolant flow, the coagulation of solid oxide particles in a lead coolant, the deposition of oxide particles on the channel walls, the crystallization of dissolved oxides on particles and dissolution of oxide particles in the lead coolant, and the transfer of formed impurities in the coolant. A system of relationships and equations is given that allows modeling of these processes as part of a software module. By integrating this module into the EUCLID/V2 code, it is possible to carry out connected calculations of physical and chemical processes in a lead coolant, which are typical for various operating conditions of a BREST-OD-300 reactor plant. To demonstrate the performance of the implemented models, the results of verification based on analytical tests and validation based on experimental data on the growth of an oxide film on the surface of stainless steel at different concentrations of oxygen in lead, obtained at the AO SRC RF-IPPE on the CM-2 circulation stand, are presented. The validation made it possible to estimate the errors in the calculation of individual parameters important for safety. [ABSTRACT FROM AUTHOR]

Boron neutron capture therapy (BNCT) can become an instrument for patients with malignant neoplasms of the rectum and colon. Here we evaluate the effectiveness of BNCT performed at the accelerator based epithermal neutron source at G. I. Budker Institute of Nuclear Physics, Siberian Division of Russian Academy of Sciences, in relation to subcutaneous xenografts of human colon adenocarcinoma SW-620 in SCID mice. Utilization of BNCT with boronоphenylalanine (BPA) and sodium borocaptate (BSH), which were injected intravenously into the retroorbital sinus, resulted in a significant decrease in tumor volumes compared to the control group (no radiation). [ABSTRACT FROM AUTHOR]

The second version of the EUCLID/V integrated code, denoted by EUCLID/V2, has been developed for analyzing the processes occurring in the course of severe accidents in sodium-cooled reactor plants with uranium dioxide fuel. Within the verification of this version that uses a 3D thermal-hydraulic module, modeling was carried out, and the prediction results were compared with the experimental data obtained on experimental setups in Germany and France on simulating accidents involving partial and complete blockage of the flow section (the first type) and also with loss of coolant flowrate (the second type). The experiments on simulating an accident involving partial blockage of the flow pass section in a 169-pin assembly (KNS 169) and on simulating an accident involving complete blockage of the flow pass section in a 37-pin assembly (SCARABEE-N BE+3) correspond to accidents of the first type, and experiments on simulating an ULOF type accident in a 37-pin assembly (KNS 37) correspond to accidents of the second type. Based on calculations carried out taking into account the available experimental data, the correctness of modeling performed using the EUCLID/V2 integrated code 3D thermal-hydraulic module is estimated, and the error of the coolant and fuel pin cladding temperatures predicted using the presented code is determined. [ABSTRACT FROM AUTHOR]

A simple theoretical model is proposed in this paper based on an analysis of the experimental data available in the available literature. It describes the rate of mass loss during the dissociation of uranium nitride in a vacuum and in a gas atmosphere due to the evaporation of substances from the surface of materials. The proposed model can be used to assess the degree of dissociation of uranium nitride, which is one of the main causes of fuel destruction, since congruent melting is observed only at high nitrogen pressures. [ABSTRACT FROM AUTHOR]