• Nuclear Engineering and Technology
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• v.49 no.8
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• pp.1629-1635
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• 2017

Reliable prediction of nuclear fuel rod behavior of nuclear power reactors constitutes a basic demand for steady-state calculations, design purposes, and fuel performance assessment. Perfect design of fuel rods as the first barrier against fission product release is very important. Simulation of fuel rod performance with a code or software is one of the fuel rod design steps. In this study, a software program called MARCODE is developed in MATLAB environment that can analyze the temperature distribution, gap conductance value, and fuel and clad displacement in both solid and annular fuel rods. With a comparison of the maximum fuel temperature, fuel average temperature, fuel surface temperature, and gap conductance in solid and annular fuel, the effects of a central hole on the fuel temperature distribution are investigated.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1756-1763
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• 2020

The paper studies spark plasma sintering (SPS) of industrially used UO₂-based fuel containing integral fuel burnable absorber (IFBA) of neutrons Gd₂O₃. Densification dynamics of pristine UO₂ powder and the one added with 2 and 8 wt% of Gd₂O₃ under ultrasonication in liquid has been studied under SPS conditions at 1050, 1250, and 1450 ℃. Effect of sintering temperature on phase composition as well as on O/U stoichiometry has been investigated for UO₂ SPS ceramics. Sintering of uranium dioxide added with Gd₂O₃ yields solid solution (U,Gd)O₂, which is isostructural to UO₂. SEM with EDX and metallography were implemented to analyze the microstructure of the obtained UO₂ ceramics and composite UO₂-Gd₂O₃ one, particularly, open porosity, defects, and Gd₂O₃ distribution were studied. Microhardness, compressive strength and density were shown to reduce after addition of Gd₂O₃. Obtained results prove the hypothesis on formation of stable pores in the system of UO₂-Gd₂O₃ due to Kirkendall effect that reduces sintering efficiency. The paper expands fundamental knowledge on pros and cons of fuel fabrication with IFBA using SPS technology.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.732-736
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• 2008

The traditional method to calculate the gravity feed is to assume that only one tank in fuel system supplies the needed fuel to the engine, and then calculated for the single branch. Actually, all fuel tanks compete for supplying oil. Our method takes into consideration all fuel tanks and therefore, we believe, our method is intrinsically superior to traditional methods and is closer to understanding the real seriousness of the oil supply situation. Firstly, the thesis gives the mathematical model for fuel flow pipe, pump, check valve and the simulation model for fuel tank. On the basis of flow network theory and time difference method, we established a new calculation method for gravity feed oil of aeroplane fuel system, secondly. This model can solve the multiple-branch and transient process simulation of gravity feed oil. Finally, we give a numerical example for a certain type of aircraft, achieved the variations of oil level and flow mass per second of each oil tanks. In addition, we also obtained the variations of the oil pressure of the engine inlet, and predicted the maximum time that the aeroplane could fly safely under gravity feed. These variations show that our proposed method of calculations is satisfactory.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1769-1785
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• 2021

The Integral Pressurized Water Reactors (IPWRs) as the innovative advanced and generation-III + reactors are under study and developments in a lot of countries. This paper is aimed at the thermal hydraulic study of the hot and average fuel sub-channel in a Generation III + IPWR by loose external coupling to the neutronic simulation. The power produced in fuel pins is calculated by the neutronic simulation via MCNPX2.6 then fuel and coolant temperature changes along fuel sub-channels evaluated by computational fluid dynamic thermal hydraulic calculation through an iterative coupling. The relative power densities along the fuel pin in hot and average fuel sub-channel are calculated in sixteen equal divisions. The highest centerline temperature of the hottest and the average fuel pin are calculated as 633 K (359.85 ℃) and 596 K (322.85 ℃), respectively. The coolant enters the sub-channel with a temperature of 557.15 K (284 ℃) and leaves the hot sub-channel and the average sub-channel with a temperature of 596 K (322.85 ℃) and 579 K (305.85 ℃), respectively. It is shown that the spacer grids result in the enhancement of turbulence kinetic energy, convection heat transfer coefficient along the fuel sub-channels so that there is an increase in heat transfer coefficient about 40%. The local fuel pin temperature reduction in the place and downstream the space grids due to heat transfer coefficient enhancement is depicted via a graph through six iterations of neutronic and thermal hydraulic coupling calculations. Working in a low fuel temperature and keeping a significant gap below the melting point of fuel, make the IPWR as a safe type of generation -III + nuclear reactor.

• Nuclear Engineering and Technology
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• v.41 no.7
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• pp.969-978
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• 2009

The ASSERT-PV subchannel code developed by AECL has been applied as a design-assist tool to the advanced $CANDU^{(R)1}$ reactor fuel bundle. Based primarily on the $CANFLEX^{(R)2}$ fuel bundle, several geometry changes (such as element sizes and pitch-circle diameters of various element rings) were examined to optimize the dryout power and pressure-drop performances of the new fuel bundle. An experiment was performed to obtain dryout power measurements for verification of the ASSERT-PV code predictions. It was carried out using an electrically heated, Refrigerant-134a cooled, fuel bundle string simulator. The axial power profile of the simulator was uniform, while the radial power profile of the element rings was varied simulating profiles in bundles with various fuel compositions and burn-ups. Dryout power measurements are predicted closely using the ASSERT-PV code, particularly at low flows and low pressures, but are overpredicted at high flows and high pressures. The majority of data shows that dryout powers are underpredicted at low inlet-fluid temperatures but overpredicted at high inlet-fluid temperatures.

• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.38-50
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• 2023

Proton exchange membrane fuel cell (PEMFC) is a portable and clean power generation device. The structural arrangement of the flow field has a significant influence on the delivery efficiency of PEMFC. In this article, a new bionic flow channel is designed based on the inspiration of a spider shape. The branch channel width and branch corner are studied as the focus, and its simulation is carried out by the method of computational fluid dynamics (CFD). The results show that when channel width/rib width and corner of the branch are 1.5 and 130° , respectively, it is the best numerical combination and the cell comprehensive performance is excellent. The final model using this numerical combination is compared with the traditional flow channel model to verify the advancement of this scheme.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.653-660
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• 2022

The interaction between UN and CdCl₂ in the LiCl-KCl molten eutectic was studied at 1023 K. The chlorination was monitored by sampling and recording the redox potential of the medium. At 1023 K the chlorination of UN with cadmium chloride in the molten LiCl-KCl eutectic proceeds completely and results in the formation of uranium chlorides. The melts of the LiCl-KCl-UCl₃ or LiCl-KCl-UCl₄ compositions can be obtained by the end of experiment depending on the presence of metallic cadmium in the reaction zone. The higher the concentration of the chlorinating agent, the faster the reaction rate. At [CdCl₂]/[UN] = 1.65 (10% excess) the reaction proceeds to completion in about 7.5 h. At [CdCl₂]/[UN] = 7 the complete chlorination takes 2.5-3 h.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.42-49
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• 1997

This experimental study was performed to find fuel property variations of the ultrasonic energy adding gasoline and improve the spray characteristics of the multipoint injector for EFI engine. The cause and effect of the characteristic improvement of the ultrasonic energy adding fuel was found out by the chemical structure analysis (NMR, IR), distillation and viscosity test. The results are obtained that the chemical property of gasoline organizition was changed aromatics to paraffins and branch index as the physical characteristics of gasoline were improved by ultrasonic energy. There were higher distillation and lower viscosity in ultrasonic energy adding gasoline.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1097-1104
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• 2023

A preliminary criticality analysis for novel pyrochemical apparatuses for the reprocessing of mixed uranium-plutonium nitride spent nuclear fuel from the BREST-OD-300 reactor was performed. High-temperature processing apparatuses, "metallization" electrolyzer, refinery remelting apparatus, refining electrolyzer, and "soft" chlorination apparatus are considered in this work. Computational models of apparatuses for two neutron radiation transport codes (MCU-FR and MCNP) were developed and calculations for criticality were completed using the Monte Carlo method. The criticality analysis was performed for different loads of fissile material into the apparatuses including overloading conditions. Various emergency situations were considered, in particular, those associated with water ingress into the chamber of the refinery remelting apparatus. It was revealed that for all the considered computational models nuclear safety rules are satisfied.

• Journal of Environmental Health Sciences
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• v.46 no.6
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• pp.719-725
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• 2020

Objectives: With the growth of national interest in fine particulate matter, many complaints about pollutants emitted from air pollution emitting facilities have arisen in recent years. In particular, it is thought that a large volume of particulate pollutants are discharged from workplaces that use Solid Refuse Fuel (SRF). Therefore, particulate contaminants generated from SRF were measured and analyzed in this study in terms of respective particle sizes. Methods: In this study, particulate matter in exhaust gas was measured by applying US EPA method 201a using a cyclone. This method measures Filterable Particulate Matter (FPM), and does not consider the Condensable Particulate Matter (CPM) that forms particles in the atmosphere after being discharged as a gas in the exhaust gas. Results: The mass concentration of Total Suspended Particles (TSP) in the four SRF-using facilities was 1.16 to 11.21 mg/Sm3, indicating a very large concentration deviation of about 10 times. When the fuel input method was the continuous injection type, particulate matter larger than 10 ㎛ diameter showed the highest particle size fraction, followed by particulate matter smaller than 10 ㎛ and larger than 2.5 ㎛, and particulate matter of 2.5 ㎛ or less. Contrary to the continuous injection type, the batch injection type had the smallest particle size fraction of particulate matter larger than 10 ㎛. The overall particulate matter decreased as the operating load factor decreased from 100% to 60% at the batch input type D plant. In addition, as incomplete combustion significantly decreased, the particle size fraction also changed significantly. Both TSP and heavy metals (six items) satisfied the emissions standards. The measured value of the emission factor was 38-99% smaller than the existing emissions factor. Conclusions: In the batch injection facility, the particulate matter decreased as the operating load factor decreased, as did the particle size fraction of the particulate matter. These results will help the selection of effective methods such as reducing the operating load factor instead of adjusting the operating time during emergency reduction measures.