Volume 88, Issue 5

The present research aims to enhance heat transfer in straight and wavy profile heat sinks using the same length and hydraulic diameter with different microchannel geometries (triangular, rectangular, trapezoidal, semi-circular, and circular) for uses in electronics, inkjet printing, high heat flux cooling of lasers, and other domains. The nanofluid employed is water/aluminum oxide (water/Al 2 O 3 ), and the flow regime is laminar. The range of Reynolds number (Re) in this study was 220 ≤ Re ≤ 550, and the concentrations of nanoparticle Al 2 O 3 with Heavy Water (2H 2 O) were 1.2 % volume. This investigation uses 3-dimensional Computational Fluid Dynamics (CFD) simulation software to investigate the heat transfer characteristics of several cross-sectioned microchannels. The numerical investigation utilizes the finite volume approach, and the CFD analysis is validated with accessible literature with different wavy profiles. According to the CFD simulation results, the microchannel with a circular cross-section has the highest heat transfer performance (up to 18 %) among the other cross-sections. The circular cross-section microchannel seemed to have the most significant increase in coolant temperature (by 9–22 %). The analysis outcomes prove that the microchannel with a circular cross-section has the highest performance for heat transfer; the triangular channel has the lowest performance under the same geometric parameters and boundary conditions. So, it is suggested that a circular microchannel can be used for a heat-carrying capacity of 150 W/cm 2 , a hydraulic diameter of 500 µm, and a Reynolds number equal to 500.

Bentonite exhibits obvious geological characteristics in different areas, and its chemical composition varies. To investigate the impact of these variations on the adsorption of Se(IV), the chemical structures and elemental contents of three types of bentonites were characterized using FTIR and XRF. By conducting a series of experiments and fitting the results with the kinetic adsorption model and the isothermal adsorption model, it was discovered that bentonite exhibits diverse adsorption modes for Se(IV). In acidic environments, the adsorption mode primarily involves forming an outer-sphere complex, whereas in neutral and alkaline environments, the primary mode is to form an inner-sphere complex. Zhi-Shin bentonite, which has low alumina content and high iron oxide content, demonstrates poor adsorption effectiveness on Se(IV) at low temperatures (less than 45 °C), but exhibits good adsorption effectiveness at high temperatures (more than 50 °C). Conversely, bentonite with high alumina content and low iron oxide content demonstrates the opposite effect. Furthermore, for bentonite with high iron oxide content, Se(IV) will form more inner-sphere complexes with iron oxide, and the adsorption behavior is not easily affected by changes in ionic strength and pH.

Design Study of Small Modular Gas-cooled Fast Reactors Employing Modified CANDLE Burnup with Radial Direction Shuffling Scheme has been performed with the power level 325–525 MWt. In this study Modified CANDLE burn-up scheme with radial direction shuffling has been employed with special attention to minimize reactivity swing during burn-up. The reactor cores are divided into 10 regions with equal volume in radial direction. The shuffling scheme of Modified CANDLE in radial direction can be described as follows. The natural uranium input is initially loaded in region 1. After 10 years of burnup the fuel in region 1 is shifter to region 2, the fuel in region 2 is shifted to region 3, etc. till the fuel of region 9 is shifter to region 10. The fuel from region 10 is taken out. Region 1–5 basically breeding zones in which plutonium is accumulated in fuels, while regions 5–10 have enough accumulated plutonium so that they contribute significantly to the power production. We call region 5–10 as burning zone. Nitride fuel is adopted as fuel in this study. Some parametric studies have been performed including variation of core height and power level. The neutronic calculations have been performed using the SRAC 2006 code with JENDL 4.0 nuclear data library. The optimized result shows the reactor could be operated 10 years continuously with maximum excess reactivity less than 1 % Δ k / k for 500 MWt output power, 160 cm core active height and 110 cm core active radius.

A good human-computer interface can improve the efficiency of operators in the main control room of a nuclear power plant (NPP) and reduce operational errors. It has been shown that ecological interface design (EID) can effectively reduce the cognitive load of users, improve the level of situation awareness, and help users to make decisions quickly and effectively. In this paper, we analyzed the feedwater deaeration system (ADG) of nuclear power plants, constructed the work domain analysis according to the abstraction hierarchy theory. The factors that affect the balance of the system are clarified, and the ecological interface is designed based on it, so that it can present the system status and present the future development trend more intuitively, and support the operator to predict the system situation. In this study, 10 volunteers with relevant knowledge background were selected for operational experiments, with subjective evaluation based on SART scale and grey theory, which verified that EID interface has significant advantages over the original interface in supporting both operator response time and accuracy.

The sustainability of nuclear energy implies the continuous research and development of fast reactor technology. This work represents a comparative analysis of fuel burnup calculations of three commercial-level fast spectrum concepts which are under research and development in Europe. The investigated designs are the European Sodium-cooled Fast Reactor, the European Lead-cooled Fast Reactor, and the European Gas-cooled Fast Reactor. MCNPX transport code was used to design three representative fuel assemblies of these fourth-generation concepts to analyze and compare their neutronic and safety parameters. The neutronic and safety analysis in this work includes the evolution of infinite multiplication factor and fissile inventory, neutron yield, the average energy of neutrons causing fission, neutron energy spectrum, neutron generation time, Doppler reactivity effect, effective delayed neutron fraction, and coolant void reactivity coefficient. The fuel burnup results showed that the ESFR is superior regarding the reactivity swing and breeding of fissile 239 Pu. On the other hand, analysis of safety parameters results showed that they depend mainly on fuel composition rather than on other design specifications.

The control room envelope (CRE) of a nuclear power plant is quite important during all kinds of the accidents. Only with the guaranteed habitability of the CRE, the operators can shut down the reactor safely during an accident with the release of hazardous chemicals or radioactive gases. In this study, Kuosheng nuclear power plant (NPP) in Taiwan had performed the inleakage test by using tracer gas technique, and six cases with different heating, ventilation and air conditioning system (HVAC) lineups were tested in this study. The test results showed that the unfiltered inleakage rate for the pressurization modes ranged from 0.063 m 3 /s to 0.098 m 3 /s and were all within the acceptance criteria of 0.212 m 3 /s. For the isolation modes, the unfiltered inleakage rate ranged from 0.240 m 3 /s to 0.321 m 3 /s and were still within the acceptance criteria of 0.944 m 3 /s. The test result provided useful information to improve the vulnerability of the CRE. It also showed that a decrease in the positive differential pressure of the CRE relative to its surroundings did not inevitably increase the unfiltered inleakage rate of the CRE if the critical boundary, such as the negative differential portions of the ventilation system, were still well sealed.