Journal Issue: Nuclear Energy and Technology
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Volume
2026 -12
Number
2
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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Direct numerical simulation of 2D and 3D bubble rise in liquid metal coolant
(НИЯУ МИФИ, 2026) Chudanov, V. V.; Aksenova, A. E.; Bayaskhalanov, M. V.; Leonov, A. A.; Makarevich, A. A.; Леонов, Алексей Анатольевич; Баясхаланов, Михаил Валерьевич
A numerical model for direct numerical simulation of compressible two-phase media is applied to the problem of gas-bubble rise in liquid lead. Because liquid metals are opaque and exhibit a very large density contrast between the gas and liquid phases, direct numerical simulation is an important tool for investigating interfacial dynamics and bubble-shape evolution. The paper presents 2D and 3D calculations performed with a two-phase flow code under development at IBRAE RAN using a previously developed surface-tension model integrated into the numerical algorithm. The numerical algorithm employs an explicit HLLC scheme with MUSCL reconstruction and equations of state to model compressible two-component media. The code is designed for the direct numerical simulation of thermal fluid dynamics in a two-phase compressible medium, including two-component mixtures, accounting for interfacial heat and mass transfer and using equations of state for Stiffened Gas or the Noble-Abel equation for weakly compressible media. The computed evolution of bubble shape and the time-dependent rise velocity are compared against experimental data for bubble rise in narrow rectangular channels. The simulated value of the rise velocity of a gas bubble with initial diameter of 3 mm agrees with the experimental average value of the rise velocity of moderate bubbles, entering the experimental channel through a nozzle of 3 mm in size, within 40%. This discrepancy is attributed to the insufficiently fine computational mesh used in the simulations.
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The rationale for opting for cement-based materials as an engineered barrier in a geological disposal facility for radioactive waste
(НИЯУ МИФИ, 2026) Tyupina, E. A.; Kozlov, P. P.; Boldyrev, K. A.; Krupskaya, V. V.
This paper provides experimental justification for selecting cement-based materials for engineered safety barriers (ESB) in geological disposal facilities (GDF) for radioactive waste. The long-term performance of three materials — Ordinary Portland Cement Concrete (OPCC), Calcium Aluminate Cement Concrete (CACC), and Nirex Reference Vault Backfill (NRVB) —was comparatively analyzed under conditions simulating groundwater impact in a crystalline rock massif. A one-year filtration experiment was conducted using synthetic groundwater at elevated pressure. The evaluation included comprehensive assessment of phase composition evolution, mechanical strength, hydraulic permeability, and chemical/electrochemical parameters of the interacting liquid phase. Results demonstrated that OPCC maintained increased content of strengthening phases (C-S-H, ettringite), enhanced mechanical strength exceeding the required minimum of 7.5 MPa, and consistently low hydraulic permeability (~10-12 m/s), meeting ESB criteria for contact with bentonite buffer. The pH of its filtrate remained below 11.5, minimizing alkaline degradation risks for bentonite. In contrast, NRVB exhibited complete dissolution of C-S-H and portlandite, resulting in significant strength reduction and high hydraulic permeability, making it unsuitable for bentonite buffer contact. For aluminate concrete, cross-reaction of metastable phase CAH10 into less dense C3AH6 caused substantial strength decrease and increased hydraulic permeability exceeding maximum permissible values (10-10 m/s), limiting its GDF application. Based on these findings, Ordinary Portland Cement Concrete emerges as the preferred material for ESB construction in GDF. These results establish foundation for subsequent geochemical modeling of long-term cement barrier evolution.
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Reconstruction of the helium to proton flux ratio in galactic cosmic rays using neutron monitor data
(НИЯУ МИФИ, 2026) Shcherbakova, K. A.; Lagoida, I. A.; Лагойда, Илья Алексеевич; Щербакова, Ксения Александровна
This paper presents a multiple linear regression framework for reconstructing the historical helium-to-proton (He/p) flux ratio of galactic cosmic rays (GCRs) leveraging long-term, ground-based neutron monitor datasets. Optimized via a Stochastic Gradient Descent (SGD) algorithm, the model was calibrated and trained on direct satellite measurements from PAMELA and AMS-02 covering the period 2006–2019 and was subsequently applied to estimate the He/p ratio for the extended period of 1980–2019. The reconstruction results show good agreement when validated against independent historical data from balloon-borne experiments. Given that the He/p ratio is a crucial indicator of cosmic ray modulation, utilizing the extensive time coverage of the neutron monitor network provides deeper insights into solar modulation dynamics over past solar cycles.
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Comparison of TALYS and EMPIRE results for 177Lu production yield assessment using Deuteron Particles from compact cyclotron
(НИЯУ МИФИ, 2026) Khorshidi, A.
Background. The radioisotope lutetium-177 (177Lu) has been suggested for utilizing in radio-immunotherapy. Now, 177Lu is mainly produced by neutron activation through nuclear reactors, although cyclotron-based radioisotope generation may also be assessed.
Methods. In this investigation, the small cyclotron located in Karaj, Iran, with a maximum deuteron energy of 14 MeV, was simulated to generate 177Lu using a 176Yb target with the TALYS and EMPIRE codes. Here, the generation yield of the 176Yb(d,p)177Yb→177Lu reaction was computed via different incident energies.
Results. The estimated cross-section amounts of the reaction (d,p) and its rival reaction (d,x) were compared with other reports. The maximum cross-section amount for the (d,p) interaction was evaluated to be 125 mb at 10.5 MeV and for the (d,x) interaction to be 121 mb at 9.5 MeV. Through Pade fitting, the computed production yields were 315 and 319 MBq/µA.h at 14 MeV deuteron energy from TALYS and EMIRE simulators, respectively.
Conclusion. For a one-hour irradiation at 100 μA beam current, the activity was approximately estimated 31.5 GBq of 177Lu at 14 MeV. The EMPIRE code’s Fermi Gas Model offers computational efficiency and predictive capability for unknown nuclei, though its limitations at low excitation energies and for deformed nuclei introduce systematic uncertainties. Further experimental validation of the calculated cross-sections and development of efficient targetry and separation chemistry are recommended for practical implementation of this cyclotron-based production route.
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Effect of dispersive and relativistic optical model potentials on the production cross-section calculation of 225Ac from 232Th using proton energy
(НИЯУ МИФИ, 2026) Ige, O. O.; Longmena, T. S.; Sunday, J. A.
Targeted Alpha Therapy (TAT) is considered the best method of treatment of malignant tissues. Alpha particles have interesting properties of destroying the cancerous cells due to their short penetration and high linear energy transfer. Hence, the use of alpha emitting radionuclides allows for targeting specific cancerous cells and killing of the individual cells while minimizing the toxicity to the surrounding healthy cells. The sources of the alpha for such application are the major concern. Investigation shows that Actinium-225 and Bismuth-213 are potential candidates for the production of alpha for TAT. Because of its short halve-life, the best method of production of Bismuth-213 is through 225Ac/213Bi generator hence the study of the production of Actinium-225. Critical literature review reveals that proton bombardment of thorium-232 is the best method of producing Actinuim-225. Therefore, the theoretical calculations of the production cross-sections were conducted using a nuclear modular code Empire. The calculated cross-sections were compared with one another and with the measured production cross-sections obtained from the experimental nuclear reaction data exchange format library contained in the nuclear data section of the International Atomic Energy Agency (IAEA), to investigate the effect of optical model’s configurations and the effect of the dispersive and relativistic optical model potentials on the production cross-section. The optical models’ configurations were designated by D1, D2 and D3 respectively for models that used to calculate coupled-channel transmission coefficients for the incident channel in addition to Distorted-Wave Born Approximation uncoupled, used for coupled-channel transmission coefficients for the incident and outgoing channel in addition to Distorted-Wave Born Approximation uncoupled, and used for Distorted-Wave Born Approximation calculation for all collective levels. The potentials are dispersive and relative potential, non-dispersive and relative potential, and the non-dispersive and non-relativistic potentials. The result obtained shows that the optical model configuration used to calculate coupled-channel transmission coefficients for the incident channel in addition to Distorted-Wave Born Approximation uncoupled produces the better effect on the production cross-section. Similarly, the model with Non-Dispesive and Non-Relativistic potentials produces netter yield while the optical model with Dispersive and Relativistic potential is more physically conservative. Hence any of the optical models can be used for the calculation of the production cross-section, regardless of the dispersive and relativistic potentials of the optical model.