To systematically evaluate the single-event-effect sensitivity and in-orbit reliability of aerospace-grade baseband processing SoC circuits, heavy-ion irradiation tests were performed on different accelerator platforms in accordance with the QJ 10005A-2018 standard to investigate single-event latch-up (SEL), single-event upset (SEU), and single-event functional interrupt (SEFI). Considering the high integration level and functional complexity of the SoC, a four-level test methodology, including design for testability (DFT), memory built-in self-test (MBIST), function-level testing, and typical application-level testing, was adopted for effect characterization, and the IRPP model was further used to evaluate in-orbit reliability in the GEO environment. The results show that the LET threshold of SEL for the SoC is no less than 79.24 MeV•cm2/mg, and the LET thresholds of SEU for flip-flops and memory cells are 15.9 MeV•cm2/mg and 16.8 MeV•cm2/mg respectively, both meeting the aerospace specifications. The on-orbit error rates of baseband processing function and typical application function are 2.20×10–5 per device per day and 7.90×10–7 per device per day, which are lower than the specified limits. All single-event effect indicators of the baseband processing SoC satisfy the requirements for aerospace applications, indicating a certain level of radiation tolerance under the tested conditions
During the electrorefining of spent nuclear fuel in molten salt for the recovery of U, Pu, and minor actinide (MA), fission products (FPs) such as rare earth and alkaline earth elements accumulate continuously, leading to the decrease of process efficiency. Thus, the purification of the spent salt and the stable immobilization of these volatile radioactive FPs chlorides still require further investigation. In this study, simulated FPs (140La, 144Ce, 90Sr) were precipitated from a LiCl-KCl molten salt system as low-volatility LaPO4, CePO4, and SrCO3, using K3PO4 and K2CO3 as precipitants. With LaPO4 as the host matrix, the precursor mixtures were sintered without pressure to produce a kind of monazite waste form with controlled stoichiometries (La1-2xSrxCexPO4). At 1350 degrees C with x <= 0.2, the crystalline component of the sintered waste pellets was found to consist exclusively of the monazite phase, while a secondary phase was notably enriched in Sr. Cerium was determined to exist in both +3 and + 4 valence states, indicating that a portion of Ce3+ substitutes for La3+, whereas another portion is oxidized to Ce4+ and forms charge-compensating pairs with Sr2+, collectively occupying two adjacent La3+ sites. MCC and PCT static leaching tests confirmed low normalized leaching rates (NRi) for La, Sr, and Ce in monazite. Furthermore, the addition of borosilicate glass (1, 10, 25, 50 wt%) to monazite reduced the leaching rates by 1-2 orders of magnitude, reaching NRi values of 4.83 & times; 10-6, 1.31 & times; 10-4, and 3.20 & times; 10-6 g m-2 d-1 for La, Sr, and Ce respectively with a 10 wt% glass addition. When the glass addition was increased to 50 wt%, the Vickers hardness attained 8.06 GPa. The monazite waste form in this work, with a maximum simulated FPs (140La, 144Ce, 90Sr) loading capacity of 57.6 wt%, exhibits high waste loading alongside excellent chemical durability and mechanical stability, demonstrating its potential as an advanced method for FPs immobilization.
Miniature Neutron Source Reactor (MNSR) is currently the research reactor with the largest number of exports in China, which has only one fuel assembly with the diameter of 230 mm and the height of 248 mm. Within the limited space of the MNSR fuel assembly, 350 fuel elements are compactly installed and fixed on the bird cage. In the past practice of MNSR commissioning and assembly, the installation of fuel elements has been time-consuming and difficult to install in place, causing the staff to contact radioactive substances for a long time. To solve the above problems, based on keeping the physical design of fuel assembly unchanged, this article has conducted optimization research on the installation structure of MNSR fuel assembly. An installation structure design scheme of adding the “straight groove” to the lower end plug of the fuel element has been proposed, which can not only improve the accuracy and efficiency of installation but also reduce other problems caused by improper installation. By computational analysis and experimental simulation, the reliability and feasibility of the installation structure design scheme have been verified. The optimized design has been successfully applied in the installation and commissioning of MNSR fuel assembly in Ghana and Nigeria LEU conversion projects, significantly simplifying the operation process, remarkably reducing the working time, and effectively decreasing the radiation intensity of the staff. It provides an important reference for the optimization and installation of MNSR fuel assembly and helps promotion and application of MNSR globally.
The nuclear power industry preferably aims to a closed nuclear fuel cycle and a transition to a two-component structure based on the joint operation of thermal and fast neutron reactors. This approach makes it possible to significantly reduce the volume of radioactive waste and increase the efficiency of using uranium fuel. Sodium fast neutron reactors currently demonstrate the highest technical readiness for commercial operation. This status has been achieved through the accumulation of operational experience from research reactors to pilot demonstration projects. Many of these reactors are currently in the process of decommissioning. Decommissioning of sodium fast neutron reactor facilities is associated with serious intellectual, material, and technological difficulties. There is still no overall experience in the world of completing the decommissioning of such facilities. Nevertheless, it is believed that the experience and competencies accumulated in these activities are key to forming a strategy for decommissioning of the future nuclear power plants with fast neutron reactors as an important final stage of the life cycle of such nuclear facilities. This is very important because decommissioning is a complex process that requires careful planning and coordination to ensure the safety of personnel, the public, and the environment in the future. In this regard, this review is devoted to an overview of the current progress in decommissioning various experimental sodium fast neutron reactor facilities. The accumulated experience, existing problems, and prospects for further work have been analyzed.
Irradiation test facilities and loops play a pivotal role in advancing the field of nuclear energy. These systems are engineered to emulate the conditions within nuclear reactors, enabling precise assessment of the performance of nuclear materials and components. They are instrumental in ensuring the safety and reliability of nuclear energy technologies and are crucial for the innovation of new nuclear materials and fuels. Moreover, they are significant in addressing key technical challenges, including material aging and irradiation damage. However, current research on these irradiation test facilities and loops is insufficient. This study aims to conduct an in-depth analysis and comparison of the design characteristics, as well as the advantages and disadvantages, of various irradiation test facilities and loops, including CARR (China Advanced Research Reactor), HFETR (High Flux Engineering Test Reactor), and CMRR (China Mianyang Research Reactor). Additionally, this research includes a thermohydraulic analysis of specific irradiation test loops, deriving thermohydraulic characteristic parameters that are essential for evaluating and ensuring the safety of the test loops under various operating conditions. This further confirms the safety of the test fuel elements, providing a solid foundation for the reliability of the irradiation testing process and the accuracy of nuclear material testing. The results of this study provide a comparative analysis of the design of irradiation test facilities and circuits and provide an important reference for improving their performance and safety.
