Sellafield (United Kingdom)

Abstract This study investigates the erosion behavior and modeling of glass particle beds under impinging jet conditions, with a focus on particle size effects and the onset of cohesion. Ultrasonic profiling is implemented to scan and measure static crater profiles. Results indicate that particle size significantly affects crater dimensions, ring peak formation, and overall crater shape. The smallest glass particles ( d 50 = 35 μm) studied deviate from the trends in crater size, yield stress, and analytical modeling established using larger particles, indicating the onset of cohesion effects at this small particle size. The standard erosion parameter worked well for modeling cohesionless particles down to a certain size limit, beyond which cohesive forces become significant. A new parameter, E τ based on particle critical shear stress, is introduced for erosion modeling in this study. The transition to cohesive behavior observed in the smallest glass particles is successfully accounted for using E τ .

This paper investigates the acoustic frequency response of a Magnox package with internal pressure ranging from below atmospheric pressure to 3 bar. Vibrational resonant frequencies are measured using electromagnetic acoustic transducers (EMATs) and a finite element (FE) model is used to aid in interpreting the experimental results. This work builds on two previous studies that explored the vibrational resonant frequency response of Magnox packages at internal pressures above atmospheric pressure and addresses a gap in the literature by extending the analysis over a wider pressure range than these packages. The results demonstrate a strong correlation between the measured and modelled frequencies, validating the accuracy of the FE model in predicting the vibrational behaviour of the Magnox package under different pressure conditions. This work provides deeper insights into the acoustic characteristics of Magnox packages, which are essential for their ongoing safe and effective management.

Unmanned Aircraft Vehicles (UAVs) are increasingly prevalent, ranging from small recreational quadcopters for aerial photography to large-scale military and commercial drones used for delivery and inspection. As UAVs transition to autonomous flight, their ability to operate safely in adverse weather conditions must be tested in a controlled, repeatable, and measurable manner. To address this need, a facility, called the WindShaper, capable of replicating unsteady and non-homogeneous wind conditions in a laboratory setting was developed. This facility allows for the free-flight testing of UAVs, with precise position and attitude determination throughout the test duration via an optical motion tracking system. Moreover, the newly introduced regulations for drone certification move in the direction of demostrating the safety of the system in case of harsh environment and require a rigorous set of means of compliance. In this study, we subjected several commercially available quadcopters to various wind conditions, including steady winds and gusts, during the critical phases of take-off, hovering, and landing. A virtual bounding box with 50 cm edge length was defined around each UAV's initial position, and their ability to remain within this boundary was measured using the motion tracking system. Additionally, tests were conducted under conditions of degraded or complete loss of positioning sensors, such as cameras, GNSS, and ultrasonic distance sensors, to evaluate the UAVs' safety in the case of a sensor failure or obstruction during a mission. The tests were also repeated with the drones in different orientations to measure their abilities to withstand lateral and back-facing winds. This newly developed testing procedure aims to establish a state-of-the-art methodology for ensuring UAV safety, efficiency, and regulatory compliance. It offers significant benefits to manufacturers, operators, and regulators by providing a robust framework for assessing UAV performance in challenging flight conditions.

In order to enhance the suppleness of a lower limb rehabilitation medical robot during the re-habilitation process, this study proposes a multi-source information fusion lower limb motion intention recognition method based on surface electromyographic signals (sEMG) and lower limb joint angles. To solve the problem of data traffic surge during the collection process, a multi-source current limiting sliding time window algorithm (MLS) is proposed. The MLS algorithm controls the data flow through a flow limiting and sliding time window mechanism to ensure the efficiency and stability of the system in handling large data volumes. On this basis, the study combines the Back Propagation Generalized Algorithm Neural-network (BPGN) to construct a prediction model for lower limb joint angles. The experimental results show that under the same conditions of the algorithm, the fusion of multi-source information reduces the average error of knee joint angle prediction by 10.8° and the average error of ankle joint angle prediction by 7.2° compared with the method using a single lower limb joint angle signal. Under the same condition of input signal, the multivariate flow-limiting sliding time-window BPGN reduced the average knee joint error by 13.6° and the average ankle joint angle error by 8.5° compared to the BPGN intent recognition. The multivariate flow-limited sliding time window BPGN reduced the mean knee error by 11.2° and the mean ankle angle error by 7.4° compared to Radial Basis Function (RBF) Neural-network intent recognition. By integrating the sEMG signal and lower limb joint angle information, the system can more accurately capture the patient’s movement intention and realize more precise lower limb rehabilitation training.

Penelitian ini bersumber pada permasalahan terkait kesadaran mahasiswa akan menjaga lingkungan masih kurang dan belum mencerminkan upaya dalam mendukung tercapainya tujuan pembangunan berkelanjutan. Berdasarkan analisis kebutuhan dilapangan dikembangkanlah e-modul berbasis ekoliterasi. Penelitian ini bertujuan untuk mengetahui tingkat validasi e-modul berbasis ekoliterasi. Metode penelitian menggunakan Research & Development (R&D) dengan menggunakan model ADDIE yang terdiri dari tahap analisis, desain dan pengembangan (develop). Instrumen penelitian yang digunakan yaitu lembar angket validasi ahli materi yang terdiri dari indikator kelayakan isi, kontekstual, penyajian materi dan ekoliterasi, ahli media memuat indikator kegrafikan, kemudahan, konsistensi dan format, penyajian dan ahli bahasa mencakup beberapa indikator yaitu komunikatif, lugas, dialogis dan interaktif, kesesuaian dengan kaidah bahasa Indonesia. Analisis data dilakukan secara deskriptif kuantitatif dan kualitatif. Hasil penelitian menunjukkan bahwa nilai rata-rata persentase secara keseluruhan mencapai 93,85% dengan kategori “sangat valid” artinya e-modul berbasis ekoliterasi dapat dikatakan layak untuk dapat diujicobakan.

Molecular dynamics and density functional theory simulations are used to predict the lattice and electronic contributions of thermophysical properties for UN, PuN, and mixed (U,Pu)N systems. The properties predicted include the lattice parameter, linear thermal expansion, enthalpy, and specific heat capacity, as a function of temperature. The simulation predictions for high temperature specific heat capacity are compared against experimental measurements to understand the behavior, and why differences in the experimental measurements are observed. The influence of adding U vacancies, N interstitials, and Pu to UN is also examined. For this, a new PuN potential parameter set is developed and used with the Kocevski UN potential, enabling the dynamics of mixed (U,Pu)N systems to be studied. How defects impact the thermophysical properties is important for understanding fuel behavior under different reactor conditions, and these mechanistic predictions can be used to support fuel performance codes where data is scarce.

The UK’s adoption of pyroprocessing of spent nuclear fuel as an alternative to the current aqueous processing routes requires a robust scientific underpinning of all relevant processes. One key process is the clean-up of the contaminated salt from the electroreducing and electrorefining processes. A proposed method for this clean-up is zone refining, whereby the tendency of the contaminants to remain in the liquid phase during melting and freezing is exploited to ‘sweep’ the contaminants to one end of the sample. Experiments were performed, utilising off-the-shelf laboratory equipment, to demonstrate the feasibility of zone refining for clean-up of electroreducing and electrorefining wastes. This was successful for the electrorefining simulant samples, with effective segregation coefficient, keff, values, which provide a measure of the degree of separation in the sample, between 0 and 1. Lower values indicate greater separation, with values of as low as 0.542 achieved here, corresponding to a reduction in RECl3 content from 10.0 wt.% to 8.4 wt.% (for 80% salt reuse). Due to difficulties in obtaining a fully homogeneous electroreducing simulant waste, it was not possible to demonstrate the feasibility of zone refining using the current experimental setup. Further research is required to elucidate the correct preparation conditions for production of homogeneous electroreducing waste simulants.