Program for Reconstructing the Relative Power Distribution in the Fuel Assembly of the IVG.1M Reactor. Verification and Application

Программа восстановления относительного поля энерговыделения в топливной сборке реактора ИВГ.1М. Верификация и применение
Sabitova R.R. Popov Y.A. Irkimbekov R.A. Bedenko S.V. Prozorova I.V. Svetachev S.N. Medetbekov B.S.
2025 Obninsk Institute for Nuclear Power Engineering, National Research Nuclear University MEPhI

Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika
2025 Issue 2 167 - 179 pp.

Physical studies on the radial energy release distribution in the fuel assembly of the IVG.1M research reactor were conducted during the reactor’s physical start-up phase after its conversion to low-enriched uranium (LEU) fuel. The research methodology involved irradiation experiments on physical mockups of LEU fuel assemblies within the reactor core, followed by measurements of gamma activity in irradiated fuel elements of the mockup. Since such studies involve dose loads on personnel, minimisation of labour and time costs is essential. This was achieved by reducing the number of measured fuel rods and reconstructing the nodal (rod-by-rod) energy release non-uniformity across the fuel assembly using the developed ENREDI program.The program employs polinomial approximation-interpolation at uniformly arranged nodal points and accounts for two-zone radial fuel profiling. This approach enabled the determination of the energy release non-uniformity factor and supported further calculations of the assembly’s absolute power. This work focuses on the description and verification of the ENREDI program through neutron-physical simulation with MCNP5, along with findings from the physical studies. This work focuses on the description and verification of the ENREDI program through neutron-physical simulation with MCNP5, along with findings from the physical studies. According to the verification results, the ENREDI program’s calculation algorithm reliably reconstructs the energy release field across the fuel assembly cross-section, with a maximum reconstruction error of 5% for peripheral fuel elements. Some underestimation of values is observed in areas with fewer nodal points in lattice rows, indicating potential improvements in accuracy for these specific regions.

energy release , energy release field recovery , interpolation , IVG.1M reactor , LEU fuel

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Institute of Atomic Energy, The National Nuclear Center of the Republic of Kazakhstan, 10 Beybit Atom St., Kurchatov, 071100, Kazakhstan
National Research Tomsk Polytechnic University, 2 Lenin Av., Tomsk, 634050, Russian Federation

Institute of Atomic Energy
National Research Tomsk Polytechnic University

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