Izvestiya vuzov. Yadernaya Energetika

The peer-reviewed scientific and technology journal. ISSN: 0204-3327

Computational Studies of Reactivity Effects in Severe Accidents, Accounting for Sodium Boiling, Fuel Cladding Melting, and Fuel Melting in a High-Power Sodium-Cooled Fast Reactor

5/18/2026 2026 - #02 Modelling Processes at Nuclear Facilities

Averchenkova E.P. Peregudov A.A. Solomonova N.V. Schekotova L.A. Khomyakov Yu.S. Chernukhina Yu.V. Volkov A.V. Shvetsov Yu. E.

DOI: https://doi.org/10.26583/npe.2026.2.16

UDC: 629.039.58

The development of fast neutron reactors is an important step in the implementation of a closed fuel cycle. The design of new and operation of existing power units requires a detailed approach to justifying their safety. An important section of the safety analysis report for any power unit is the calculation analysis of accidents that could lead to severe radiation consequences – beyond design basis accidents. The article presents the results of computational studies of reactivity effects and their methodological components of error in a severe beyond design basis accident accompanied by boiling of sodium in the core, melting of steel and fuel assemblies in a high-power fast reactor with sodium coolant. Today, virtually all neutronic codes simulating severe reactor accidents use a diffusion approach to solving the neutron transport equation. It is important to evaluate the methodological error component introduced by this approach. For this purpose, a comparison was made of the reactivity effects obtained using the neutron-physical module MOST and the MMKK computer program, which use the diffusion method for solving the neutron equation and the Monte Carlo method, respectively. Two test models of the core of a high-power fast reactor with sodium coolant and loaded with oxide and nitride mixed uranium-plutonium fuel were selected as the calculation model.

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beyond design basis accident sodium coolant reactivity effects error assessment diffusion codes precision codes accidents MOX fuel SNUP fuel neutronics calculations methodological amendments

Link for citing the article: Averchenkova E.P., Peregudov A.A., Solomonova N.V., Schekotova L.A., Khomyakov Yu.S., Chernukhina Yu.V., Volkov A.V., Shvetsov Yu. E. Computational Studies of Reactivity Effects in Severe Accidents, Accounting for Sodium Boiling, Fuel Cladding Melting, and Fuel Melting in a High-Power Sodium-Cooled Fast Reactor. Izvestiya vuzov. Yadernaya Energetika. 2026, no. 2, pp. 238-253; DOI: https://doi.org/10.26583/npe.2026.2.16 (in Russian).

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