Journal Issue: Nuclear Energy and Technology (NUCET)
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Volume
2026 -12
Number
1
Issue Date
Journal Title
Nuclear Energy and Technology (NUCET)
Journal ISSN
2452-3038
Том журнала
Том журнала
Nuclear Energy and Technology (NUCET)
Nuclear Energy and Technology (NUCET) (2026 -12)
Статьи
Публикация
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Evaluation of the excitation function for alpha particle induced reactions on the target of 59Co using PACE4 code
(НИЯУ МИФИ, 2026) Urgessa T
Theoretical excitation functions for the alpha particle-induced reactions 59Co(α,2p4n)57Co, 59Co(α,2pn)60Co, and 59Co(α,4p5n)54Mn were analyzed and compared to the experimental excitation functions. Experimental cross sections were calculated using the PACE4 and TALYS-2.0 statistical model codes across an energy range of 33.1–54.5 MeV. PACE4 calculations used different values of level density parameters at k = 8–10, while TALYS-2.0 calculations were performed with multiple level density models (ldmodel 1–5). The analysis also examined the sensitivity and uncertainty of theoretical cross sections to changes in level density parameter. A quantitative comparison of the experimental and theoretical excitation functions was performed using calculations of reduced chi-square (χ2red) and normalized root mean square deviations (NRMSD). The findings indicate that PACE4 calculations more accurately reflect both the size and form of the experimental excitation functions compared to TALYS-2.0 calculations for the reaction channels studied. The quantitative analysis indicates the predominance of the compound nucleus reaction mechanism, suggesting that pre-equilibrium and direct contributions have a minimal impact within the energy ranges studied. This study provides a thorough justification for the nuclear theoretical models and offers consistent nuclear reaction data for alpha particle-induced reactions on a 59Co target.
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Safety-oriented CFD analysis of the PeLUIt-40 pebblebed HTGR under partial flow and LOCA scenarios
(НИЯУ МИФИ, 2026) Afif, M. T.; Sulistyo, F. Y.; Veretennikov, D. G.
In this study, the thermal–hydraulic behavior of the Indonesian Micro Reactor PeLUIt-40, a 40 MWt modular pebble-bed high-temperature gas-cooled reactor (HTGR), was analyzed under reduced coolant flow and loss-of-coolant accident (LOCA) conditions. Three-dimensional computational fluid dynamics (CFD) simulations using a porous-media core model and volumetric heat sources from neutronic analysis were performed. Steady-state simulations were conducted for helium flow rates from 100% to 25% of nominal, and a transient LOCA was simulated by reducing flow to zero over ten seconds. The results show that maximum core temperatures increased nonlinearly with reduced flow, exceeding TRISO fuel limits at 25% flow, while outlet duct temperatures remained well homogenized. During the LOCA, passive buoyancy-driven circulation limited temperature rise, stabilizing around 1026 °C. These findings provide preliminary insight into PeLUIt-40 thermal hydraulics, highlighting the need for further validation and extended transient analysis to confirm safety margins.
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Frequency regulation in high-renewable grids using small modular reactors (SMR): a comparison of pid and mpc strategies
(НИЯУ МИФИ, 2026) Elfaramawy, R. M.; Sarhan, A. A.; Helmy, S.; El-Wakeel, A. S.
The rapid penetration of renewable energy sources (RESs) into modern power systems has introduced unprecedented challenges in frequency regulation, primarily due to the intermittency and variability of wind and solar generation. Traditional large-scale nuclear and fossil-fuel-based power plants, while reliable, lack the flexibility required for rapid response to frequency fluctuations in high-renewable environments. Small modular reactors (SMRs) have emerged as a promising alternative, combining nuclear reliability with enhanced operational flexibility (Elfaramawy et al. 2025).
This research presents a comparative study of two control strategies—proportional-integral-derivative (PID) and model predictive control (MPC)—for frequency regulation in a renewable-rich grid, where SMRs act as flexible balancing resources. Using validated Simulink-based dynamic models of SMR dynamics, grid frequency response, and renewable variability, the performance of PID and MPC controllers in mitigating disturbances caused by renewable fluctuations and large-scale contingencies was analyzed.
Results indicate that both controllers provide effective frequency regulation, with MPC offering modest advantages in overshoot suppression and settling time. While PID demonstrates reliable performance and ease of deployment, MPC enables predictive optimization and explicit constraint handling. The findings suggest that both control strategies are viable for SMR-based frequency support, with MPC providing incremental improvements in dynamic response for future high-renewable grids.
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Pretreatment of radioactive concentrate from leadbismuth cooled fast reactors: flocculant screening and process optimization
(НИЯУ МИФИ, 2026) Peng, S.; Wang, D.; Li, S.; Li, J.; Xie, H.
The processing of radioactive concentrates generated during the operation of lead bismuth fast reactors is extremely difficult, with complex components including heavy metals such as Pb and Bi, radioactive nuclides such as Cs, Sr, and Co, alpha emitters such as 210-Po, as well as organic matter and suspended particles. This study focuses on the pretreatment challenges of this radioactive liquid waste, systematically screening 13 types of mature commercial flocculants and evaluating their efficiency in the flocculative removal of key heavy metals and simulated radionuclides from the concentrate. The experimental results showed that the flocculant #9 had a removal efficiency of over 99% for Pb, Bi, and Co within 20 minutes, and a removal efficiency of 96% for the 210-Po analog element Te. The effluent pH was close to neutral, which was superior to other reagents. Through optimization via single-factor experiments and Response Surface Methodology, the optimal process parameters for flocculant #9 were determined as follows: pH 7.8, dosage of 1.17 g/L, and flocculation time of 15.9 minutes. This study provides an efficient and low-cost pretreatment process for radioactive concentrate from lead-bismuth reactors, which can significantly reduce the subsequent deep purification load of 21°Po and offers technical support for the optimization of nuclear waste liquid treatment processes.
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Modernization of the SC-INT subchannel thermalhydraulic code
(НИЯУ МИФИ, 2026) Vertikov, E. A.; Zaporzhin, K. V.; Oleksyuk, D. A.; Khamaza, V. A.; Khudykin, A. M.; Glazov, M. A.; Morozkin, O. N.
The article presents the main results of the work cycle on modernizing the source code of the SC-INT computer program designed for subchannel thermal-hydraulic calculations of the water-cooled nuclear reactors cores. The mathematical description of the program is briefly provided, including the method of allocation of control volumes in space, the discrete analog of the basic conservation laws forming the system of nonlinear equations, as well as the method of its solution. The path passed on the internal modernization of the program is described in detail: ejection of outdated Fortran programming language constructions, transition to structure-oriented approach of writing source code, development of modular architecture, as well as implementation of the alternative numerical algorithm for solving the main system of nonlinear equations using the PETSc library. As an example of the SC-INT program capabilities, which appeared after the above described modernizations, the results of thermal-hydraulic calculation in fine-mesh subchannel approximation of a full-scale VVER-1000 reactor core are presented. The core under consideration is assembled from fuel assemblies of different designs: with and without installed «Vikhr» and «Progonka» type intensifier grids. It is demonstrated that the residuals on the main coolant parameters achieved in the simulation of the full-scale core match in order with the corresponding values characteristic for calculations of small-scale experimental fuel assembly models. Thermal-hydraulic calculations of full-scale cores in the subchannel approximation opens the possibility for development of coupled program complexes designed for improved estimation of the parameters of multiphysics processes in the cores of water-cooled nuclear reactors.