• Proceedings of the KSME Conference
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• 2001.06d
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• pp.343-347
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• 2001

Advanced Pressurized Reactor 1400(APR-1400), which is a standard evolutionary advanced light water reactor(ALWR), has been developed from 1992 as one of long-term Government Project(G-7). The APR-1400 is designed to operate at the rated output of 4000MWt to produce an electric power output of around 1450MWe. The balance of plant (BOP) for the secondary system consists of main steam, feedwater, condensate, turbine generator and auxiliary system. In this paper, we describe the major design features of secondary component, balance of plant configuration, and then the turbine cycle thermal performance evaluation using PEPSE code.

• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.71-78
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• 2009

One of main concepts involved in regional small nuclear reactors is unmanned remote control. Internet-based virtual private networks provide environments for the remote monitoring and control of geographically-dispersed systems, and with the advances in communication technologies, the potential of networks for real time control and automation becomes enormous. However, networked control has some problems. The most critical is delay in signal transmission, which degrades system stability and performance. Therefore, a networked control system should be designed to account for delay. This paper proposes some design approaches for a delay-tolerant system that can guarantee predetermined stability margins and performance. To accomplish this, the reactor plant is modeled with consideration of uncertainties. With this model, three kinds of controllers are developed using different methods. The designed systems are compared with respect to stability and performance, and a second-order controller designed using the table lookup method was found to give the most satisfactory results.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.3071-3079
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• 2023

Helium production in the nuclear fuel matrix during irradiation plays a critical role in the design and performance of Gen-IV reactor fuel, as it represents a life-limiting factor for the operation of fuel pins. In this work, a surrogate model for the helium production rate in fast reactor MOX fuels is developed, targeting its inclusion in engineering tools such as fuel performance codes. This surrogate model is based on synthetic datasets obtained via the SCIANTIX burnup module. Such datasets are generated using Latin hypercube sampling to cover the range of input parameters (e.g., fuel initial composition, fission rate density, and irradiation time) and exploiting the low computation requirement of the burnup module itself. The surrogate model is verified against the SCIANTIX burnup module results for helium production with satisfactory performance.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.191-198
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• 2011

According to the propagation of fuel cell system, the importance of that system efficiency is being magnified. Thus, the efficiency improvement of reformer which is the important factor of fuel cell system will be required. This study has been experimentally performed to evaluated the performance of plate type STR reactor. At first, we changed fuel flow rate (2, 3 and 4 l/min) in burner, and then we measured a proportion of hydrogen in produced gas through the STR reactor by G.C for evaluating the performance of plate type STR reactor in various fuel supply conditions. And we changed S/C ratio (2 and 4) and measured a proportion of hydrogen in produced gas through the STR reactor. As a results, condition at fuel flow rate 2 and 3 l/min could not be supplied amount of heat for STR sufficiently. Condition at fuel flow rate 4 l/min could supplied a heat excessively. And condition at S/C ratio 2, reaction occurred insufficiency. But condition at S/C ratio 4 was excess. From above, we found the optimum conditions that were fuel rate 3.5 l/min and S/C ratio 3.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.937-946
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• 2020

The aim in the present work is to simulate accident scenarios of AP1000 during the small-break loss-of-coolant accident (SBLOCA) and investigate the performance and behavior of automatic depressurization system (ADS) during accidents by using MIDAC (The Module In-vessel Degradation severe accident Analysis Code). Four types of accidents with different hypothetical conditions were analyzed in this study. The impact on the thermal-hydraulic of the reactor coolant system (RCS), the passive core cooling system and core degradation was researched by comparing these types. The results show that the RCS depressurization becomes faster, the core makeup tanks (CMT) and accumulators (ACC) are activated earlier and the effect of gravity water injection is more obvious along with more ADS valves open. The open of the only ADS1-3 can't stop the core degradation on the basis of the first type of the accident. The open of ADS1-3 has a great impact on the injection time of ACC and CMT. The core can remain intact for a long time and the core degradation can be prevent by the open of ADS-4. The all results are significant and meaningful to understand the performance and behavior of the ADS during the typical SBLOCA.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.1974-1987
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• 2023

The load-following operation of small modular reactors (SMRs) requires accurate prediction of transient behaviors that can occur in the balance of plants (BOP) and the nuclear steam supply system (NSSS). However, 1-D thermal-hydraulics analysis codes developed for safety and performance analysis have conventionally excluded the BOP from the simulation by assuming ideal boundary conditions for the main steam and feed water (MS/FW) systems, i.e., an open loop. In this study, we introduced a lumped model of BOP fluid system and coupled it with NSSS without any ideal boundary conditions, i.e., in a closed loop. Various methods for coupling boundary conditions at MS/FW were tested to validate their combination in terms of minimizing numerical instability, which mainly arises from the coupled boundaries. The method exhibiting the best performance was selected and applied to a transient simulation of an integrated NSSS and BOP system of a SMART. For a transient event with core power change of 100-20-100%, the simulation exhibited numerical stability throughout the system without any significant perturbation of thermal-hydraulic parameters. Thus, the introduced boundary-condition coupling method and BOP fluid system model can expectedly be employed for the transient simulation and performance analysis of SMRs requiring daily load-following operations.

• Journal of Environmental Health Sciences
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• v.39 no.3
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• pp.289-299
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• 2013

Objectives: For the field application of the dielectric barrier discharge plasma reactor, scale-up of the plasma reactor is needed. This study investigated the possibility of inactivation of microorganisms in sewage using pilot multi-plasma reactor. We also considered the possibility of degradation of total organic carbon (TOC) and nonbiodegradable matter ($UV_{254}$) in sewage. Methods: The pilot plasma reactor consists of plasma reactor with three plasma modules (discharge electrode and quartz dielectric tube), liquid-gas mixer, high voltage transformers, gas supply equipment and a liquid circulation system. In order to determine the operating conditions of the pilot plasma reactor, we performed experiments on the operation parameters such as gas and liquid flow rate and electric discharge voltage. Results: The experimental results showed that optimum operation conditions for the pilot plasma reactor in batch experiments were 1 L/min air flow rate), 4 L/min liquid circulation rate, and 13 kV electric discharge voltage, respectively. The main operation factor of the pilot plasma process was the high voltage. In continuous operation of the air plasma process, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal condition of 13 kV were $10^{2.24}$ CFU/mL, 56.5% and 8.6%, respectively, while in oxygen plasma process at 10 kV, residual microorganisms, $UV_{254}$ absorbance and TOC removal rate at optimal conditions were $10^{1.0}$ CFU/mL, 73.3% and 24.4%, respectively. Electric power was increased exponentially with the increase in high voltage ($R^2$ = 0.9964). Electric power = $0.0492{\times}\exp^{(0.6027{\times}lectric\;discharge\;voltage)}$ Conclusions: Inactivation of microorganisms in sewage effluent using the pilot plasma process was done. The performance of oxygen plasma process was superior to air plasma process. The power consumption of oxygen plasma process was less than that of air plasma process. However, it was considered that the final evaluation of air and oxygen plasma must be evaluated by considering low power consumption, high process performance, operating costs and facility expenses of an oxygen generator.

• Clean Technology
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• v.21 no.4
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• pp.229-234
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• 2015

Recently, there are increasing numbers of study regarding hydrogen fuels but researches on desulfurization of diesel are rare. In this study, we performed diesel desulfurization reactor design by computation fluid dynamics simulation. By analyzing the change in flow and sulfur concentration at the outlet according to the changes in flow rate, reactor length, and reactor diameter, we have found the minimum catalyst performance for the given flow rate condition and the relation between the reactor performance and the reactor size and shape. We also studied the effects of permeability of the packed bed on the flow and sulfur concentration distribution. The present work can be utilized to design a diesel desulfurization reactor for a fuel cell used in ships. Furthermore, the present work also can be used to design low sulfur diesel supply in oil refineries and therefore contribute to the development of clean petrochemical technology.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.310-323
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• 2023

The k-eigenvalue neutronics/thermal-hydraulics coupling calculation is a key issue for reactor design and analysis. Jacobian-free Newton-Krylov (JFNK) method, featured with super-linear convergence rate and high efficiency, has been attracting more and more attention to solve the multi-physics coupling problem. However, it may converge to the high-order eigenmode because of the multiple solutions nature of the k-eigenvalue form of multi-physics coupling issue. Based on our previous work, a modified JFNK with a line search method is proposed in this work, which can find the fundamental eigenmode together with thermal-hydraulics feedback in a wide range of initial values. In detail, the existing modified JFNK method is combined with the line search strategy, so that the intermediate iterative solution can avoid a sudden divergence and be adjusted into a convergence basin smoothly. Two simplified 2-D homogeneous reactor models, a PWR model, and an HTR model, are utilized to evaluate the performance of the newly proposed JFNK method. The results show that the performance of this proposed JFNK is more robust than the existing JFNK-based methods.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.237-240
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• 2002

Micro catalytic reactors are alternative propulsion device that can be used on a nano satellite. When used with a monopropellant, $H_2O_2$, a micro catalytic reactor needs only one supply system as the monopropellant reacts spontaneously on contact with catalyst and releases heat without external ignition, while separate supply lines for fuel and oxidizer are needed for a bipropellant rocket engine. Additionally, $H_2O_2$ is in liquid phase at room temperature, eliminating the burden of storage for gaseous fuel and carburetion of liquid fuel. In order to design a micro catalytic reactor, an appropriate catalyst material must be selected. Considering the safety concern in handling the monopropellants and reaction performance of catalyst, we selected hydrogen peroxide at volume concentration of 70% and perovskite redox catalyst of lantanium cobaltate doped with strondium. Perovskite catalysts are known to have superior reactivity in reduction-oxidation chemical processes. In particular, lantanium cobaltate has better performance in chemical reactions involving oxygen atom exchange than other perovskite materials. In the present study, a process to prepare perovskite type catalyst, $La_{0.8}Sr_{0.2}CoO_3$, and measurement of its propellant decomposition performance in a test reactor are described.