Four different magnetic Fe₃O₄nanoparticles were synthesized and characterized by solvothermal method based on different sodium salts. Sodium salts which were used to synthesize the nanoparticles were NaOAc, Na₂CO₃, a mixture of NaOAc and Na₃Cit, and a mixture of NaOAc and Na₂C₂O₄. The structural and optical properties of the synthesized nanoparticles were examined by XRF, XRD, SEM and FT-IR. The results estimated from XRD pattern and SEM image indicated that the second sample (Na₂CO₃) had the lowest average particle and crystallite size around 29 nm and 43 nm. It was also shown that the first (NaOAc) and second (Na₂CO₃) samples had the best FT-IR spectra, similar to the available commercial sample which was provided by Merck. At last, the prepared Fe₃O₄nanoparticles were applied as sorbents to sorb uranium ions (U(VI)) from radioactive wastewater. The adsorption results showed that the highest U(VI) adsorption was obtained for the second sample in the solution with pH around 10.

Small modular reactors (SMRs) represent a key area of interest to nuclear industry developers, which have been making significant progress during the past few years. Generally, these reactors are promising owing to their improved safety due to passive systems, enhanced containment efficiency, and fewer capital costs in comparison to traditional nuclear reactors. An important advantage of SMRs is their adaptability in being coupled to other energy-consuming systems, such as desalination plants (DPs) to create a cogeneration plant. Considering the serious challenges regarding the freshwater shortage in many regions of the world and the necessity of using low-carbon energy sources, it is advantageous to use SMR for supplying the required heat and electricity of DPs. As a high-performance desalination technology, the hybrid desalination (HD) systems can be exploited, which retain the advantages of both thermal and membrane desalination methods. In this study, several SMR coupling schemes to HD plants have been suggested. In performing a thermodynamic analysis of integrated SMR-DP, the International Atomic Energy Agency (IAEA) Desalination Thermodynamic Optimization Program (DE-TOP) has been utilized. It has been found that the use of relatively hot water from the SMR condenser leads to about 6.5 to 7.5% of total desalination cost reduction, where the produced electricity and hot steam extracted from low-pressure turbine were used to drive the HD system.

The competitiveness of small modular reactors (SMRs) has been planned based on design simplification, short construction time, passive safety systems, and enabling self-financing by ramp-up construction. Due to the global energy challenges, SMRs have received pervasive attention from a wide range of researchers, designers, developers, stakeholders, and customers. Besides the many advantages related to the design of SMRs, there are challenges ahead of these reactors. SMR licensing is one of the most critical challenges in the front deployment of these reactors. This challenge stems from innovations in SMR designs and systems, such as modularity or deployment for desalination, energy storage, hydrogen production, process heat, and district heating. Due to the lack of experimental data and technical knowledge, the licensing challenges for non-water coolant SMRs are more complicated. Nearly all previous generation reactor licenses were based on conservative analysis while the decision-making methods based on best-estimate and realistic approaches have received more attention in recent years. Thus, the method known as the best estimate plus uncertainty (BEPU) approach is selected for licensing in some cases. At this time, using the BEPU approach in licensing for conventional NPPs is a mature technology and ready for industrial application. Nevertheless, because most previous reactors were licensed based on conservative methods, developers and even regulatory bodies resist re-assessments based on the BEPU approach, while using the choice of conventional conservative methods is a type of roll-back for next-generation SMRs. Thus, this work reviews the BEPU approach and clarifies the possibility of using this approach in the licensing process of SMRs. The lack of experimental data and tight coupling of phenomena along with uncertainty quantification are the main challenges ahead of using BEPU in the licensing process of SMRs.

An accurate prediction of fission gas release is an important issue for fuel rod heat transfer because it has a significant impact on the prediction of gap conductance and, therefore, fuel temperatures. To do this, we previously developed a physics-based code for prediction of fission gas behavior with considering grain growth in UO2 fuel (SS code). This code is used as a subroutine in FRAPCON 3.1 code. Such physics-based codes enable us to more accurately examine the swelling caused by fission gases. Initially, the effect of temperature changes and grain growth on the fission gases behavior was investigated, and the results are used to calculate the fuel and gap thermal conductivity coefficients. Separate-effect results show that intra-granular bubble swelling remains negligibly low (on the order of 10⁻⁴), exerting almost no direct influence on fuel thermal conductivity. Integral effect simulations for BR-3 Rod 24-I-6 and IFA-432 Rod 1 demonstrate that the SS subroutine predicts fission gas release fractions in good agreement with measured data and with the FORMAS method. The results further indicate that gap thermal conductivity decreases with increasing fission gas release and burnup due to the accumulation of low-conductivity fission gases (xenon and krypton) in the fuel-cladding gap.