Algerian Journal of Engineering and Technology

Integrated Experience Feedback-Knowledge Management Approach for Enhanced Safety of a Research Reactor

Ahmed Bourenane — 2025-11-28

In the nuclear field, safety is a fundamental requirement, driven by the need to protect workers, the public, and the environment from the effects of ionizing radiation. Nuclear safety increasingly relies on organizations' ability to manage their knowledge effectively in a context marked by rapid technological changes, skills renewal constraints, and growing operational complexity. Two complementary approaches play a strategic role in sustainably strengthening nuclear safety: Experience Feedback (EF) and Knowledge Management (KM). This article is based on a qualitative analysis of IAEA safety standards and technical documents, combined with the author's professional experience. The proposed integrated EF-KM cycle is derived from this analysis and is presented as a conceptual framework for implementation. The synergy between EF and KM contributes to the overall performance of safety systems by preventing error repetition, preserving tacit knowledge, and fostering a proactive safety culture. This article constitutes a direct advocacy for research reactor operating organizations to formally establish and integrate robust EF and KM programs as a strategic necessity, rather than treating them as optional initiatives. The paper also discusses implementation challenges and provides global success cases from EDF, WANO, and Bruce Power to ground the theoretical framework in practical reality. A practical example involving a transient iodine release is used to illustrate the operational benefits.

Microstructural study of ytterbium zirconate pyrochlore synthesized by the mixed method: sintering/chemical infiltration

Dalila Moudir — 2025-11-24

In this study, a zirconate pyrochlore with the chemical formula (Yb₀.₁Ba₀.₉)₂Zr₂O₇ was synthesized and stabilized by ytterbium nitrate. The used synthesis method combined between calcination and infiltration procedure where the considered infiltration parameters were concentration of ytterbium solution set at C=390 g/L, infiltration temperature and T= 105°C. However the thermal cycle of sintering in two stages, calcination at 550°C for 4 h, then a sintering of 1200°C for 24h. The characterization of the synthesized material was carried out by several analysis techniques. Archimedes' density using a hydrostatic balance gave a value of 4.001 g/ cm³ for the raw ceramic and 4.665g/cm³ for the sintered one. X-ray diffraction (XRD) analysis was used to track the progress of the synthesis and confirm its success through the formation of the ZrO₂ structure, the main framework of the pyrochlore material. Observation using a scanning electron microscope (SEM) allowed us to observe the distribution of grains and pores and estimate the quality of sintering, combined with analysis using X-ray energy dispersive spectrometry (EDX), which allowed us to check the global chemical composition of the sintered matrix. Fourier transform infrared (FTIR) analysis of pyrochlore (Yb₀.₁Ba₀.₉)₂Zr₂O₇ shows essential absorption bands between 400-4000 cm⁻¹.Two absorption bands can be seen at 470 cm⁻¹corresponding to Zr-O vibrations, and an absorption band at 682 cm⁻¹ corresponding to Ba-O vibrations.

Steady-State thermal-hydraulic and neutronic analysis of the NUR research reactor current configuration

Ourida Mokhtari — 2025-11-06

Maintaining adherence to safety standards and limitations throughout a nuclear reactor's operational life is crucial to preventing incidents and accidents that could have detrimental effects on workers, the general public, and the environment. The integrity of the fuel, and specifically the first safety barrier (the fuel cladding), must be maintained in order to reduce the likelihood of an accident. Compliance with these limits ensures that even at the hottest point of the reactor core, the safety limits cannot be exceeded. This study provides a thermal-hydraulic and neutronic analysis of the currentconfiguration of the NUR research reactor under steady-state conditions. Its primary aim is to ensure that all the critical thermal-hydraulic parameters uphold margins below the safety limits. The neutronics calculations were performed using OpenMC code validated by the obtained results of WINS/CITVAP ,power density distribution and Power Peaking Factors (PPFs) were calculated. The PPFs for each channel in the core are obtained, and the hot one is then localized. These results were injected in thermal-hydraulic model established by PARET code, in which the core was divided into two regions (two parallel fuel platesand their associated cooling channels). The first region represents the hottest channel in the core, and the second one, the remainder part named the average channel. This model provides the evolution of the fuel, coolant, and cladding temperatures in the hot channel. The temperature profiles generated were compared to those of the asymptotic model of a previous work and those acquired by the TERMIC.1H code in order to validate the PARET model for the reactor core. Consequently, under steady-state conditions, the clad's maximum temperature remained well below the safety limit. The most significant obtained result is that the NUR research reactor can safely operate at a nominal power while staying within the thermal safety limitations.

Multi-parametric study of welding parameters on the durability of CANDU fuel assemblies

Amane Sahli — 2025-11-06

This study focuses on TIG (Tungsten Inert Gas) welding of Zircaloy-4, used in fuel rod assemblies for CANDU (Canada Deuterium Uranium) reactors, to analyze the effect of welding parameters on the microstructural and mechanical quality of end-plug-to-cladding joints. Despite the extensive use of TIG welding for Zircaloy-4, understanding the induced metallurgical phenomena that affect mechanical properties remains a major challenge. This study aims at systematic characterization of welding parameter effects on microstructure and properties of plug-cladding joints, identifying metallurgical zones and correlating operating conditions with final performance. Welds were produced under various conditions of current intensity and rotation speed and examined using optical microscopy, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Vickers microhardness, and hydraulic burst tests. The analysis revealed three distinct zones: fusion zone (FZ), heat-affected zone (HAZ), and base metal (BM) with typical Widmanstätten structures. A clear correlation was found between heat input, hardness, and mechanical strength. Hydraulic burst tests confirmed the high performance of optimized welds, showing failure stresses of approximately 425 ± 10 MPa.

Hydrodynamic Parameters Study of Gas-Solid Fluidized Bed Reactor: Case of AUC Conversion to UO2

Smain Korichi — 2025-11-06

The fluidization technique is used for gas-solid interaction processes whenever high rates of heat and mass transfer between the two constituents is required. This work aims to contribute to the understanding of the hydrodynamic parameters of gas-solid fluidized bed reactors in the case of the conversion of AUC powder (ammonium uranyl carbonate) into UO₂ powder (uranium dioxide). The study focuses on the fluidization velocity effect on the pressure drop evolution during the fluidized bed process, as function of the temperature and type of gas used (pure N₂, pure H₂, and a 50% H₂–50% N₂ mixture). The study will also present the results of the gas flow rate variation as a function of temperature, as well as the results of the pressure drop variation as a function of the fluidization velocity, taking temperature as a parameter for pure N₂, pure H₂ and 50% H2-50% N₂ mixture. Calcination-reduction experiments were conducted, using a fluidized bed reactor to convert AUC powder into UO₂. These experiments examined the influence of process parameters on particle size, specific surface area, O/U ratio and porosity of the UO₂ powder produced. Using the optimized operating parameters, such as the fluidization velocity, gas flow rates, and treatment temperature of the fluidized bed reduction-calcination process, ensured the production of UO₂ powders with the required physicochemical characteristics.