Izvestiya vuzov. Yadernaya Energetika

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

Investigation of the Effect of Using a Radial Reflector on the Neutron-Physical Characteristics of the Small-Module Reactors

9/17/2026 2026 - #03 Modelling processes at nuclear facilities

Vorontsova A.A. Vnukov R.A. Kolesov V.V.

DOI: https://doi.org/10.26583/npe.2026.3.13

UDC: 621.039.5

Small-module installations are convenient due to their small size, which allows them to be installed in places unsuitable for the placement of power reactors. However, this advantage is also their disadvantage: the small size of the core leads to an increase in neutron leakage. One of the ways to solve this problem may be to use a neuron reflector made of various materials. This work is devoted to the study of the effect of a graphite reflector placed behind the reactor vessel on the neutron-physical characteristics of small-module reactors using the SVBR-100 reactor model as an example. It is proposed to consider the effect of reflector thickness on the spectrum of neurons, energy release and duration of the fuel campaign. Models with a step-by-step increase in the graphite layer during the campaign from 0 to 20 cm in increments of 2, 5 and 10 cm are proposed. With this approach, there is no reflector at the beginning of the campaign, and the thickness of the reflector changes when the Keff value is less than 1,000. When modeling such a campaign, it was noticed that each of the considered steps allows you to get a gain in the length of the fuel campaign, which turns out to be almost identical. The use of a reflector has a strong effect on peripheral fuel assemblies: the placement of the reflector leads to an equalization of energy release within the fuel assemblies, and also contributes to the shift of the neutron spectrum to the thermal region, while the center of the core remains virtually unchanged. When considering the composition of the discharged fuel at the end of the campaign for models with a reflector, there is a decrease in the amount of plutonium compared to the initial model, but its purity improves. At the same time, the size of the reflector does not affect the quality of plutonium. The proportion of minor actinides remains less than 1% for all the models under consideration. In general, the use of a graphite reflector has a positive effect on the neutron-physical characteristics of the reactor, including an increase in the wavelength and equalization of the energy release field. In the future, it is planned to study other reflector materials, such as beryllium and zirconium hydride.

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neutron reflector graphite energy release neutron spectrum isotopic composition

Link for citing the article: Vorontsova A.A., Vnukov R.A., Kolesov V.V. Investigation of the Effect of Using a Radial Reflector on the Neutron-Physical Characteristics of the Small-Module Reactors. Izvestiya vuzov. Yadernaya Energetika. 2026, no. 3, pp. 182-195; DOI: https://doi.org/10.26583/npe.2026.3.13 (in Russian).

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