• 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.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.38-40
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• 2006

Nuclear power plants are urged to reduce operating and maintaining costs to remain competitive as well as to increase the safety preventing the radioactive material to the atmosphere. To reduce the cost and to increase the safety, the inspection of balance-of-plant heat exchanger becomes important. However, there are some problems for plugging the heat exchanger tubes since the criterion and its basis are not clearly described. The codes and standards related to show the tube plugging criteria may not exist currently. In this paper, a method to establish the tube plugging criteria of BOP heat exchangers is introduced and the tube plugging criteria for the non-regenerative heat exchanger in the steam generator blow-down system of nuclear power plant. This method relies on the similar method used to establish the plugging criteria for the steam generator tubes.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.21-24
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• 2008

We have developed a $kW_e$ class liquid fuel based solid oxide fuel cell (SOFC) system. Our final target is to develop the 1 $kW_e$ diesel based SOFC system for residential power generator(RPG). In this study, we present the conceptual design of SOFC system. System is composed of hot-box and cold-box. Planar typed SOFC stack, heat exchanger, combustor for stack tail gas, and fuel processor, such as fuel reformer and desulfurizer, are contained in the hot-box. And several balance of plants(BOP), such as fuel suppliers and controller, are contained in the cold-box. Before the SOFC system fabrication, we have already operated the selfsustaining fuel processor, and heat exchange of all heat-related components is simulated using ASPEN HYSYS, because heat maintenance and management in hot-box are important for stable operation of SOFC system. The self-sustained fuel processor was successfully operated for about 250 hours, and heat exchange is enough to operate the SOFC system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1193-1198
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• 2011

The solenoid valve used in fuel cell system need to have good sealing performance because the work fluid can explode in the system. Moreover, the temperature of the work fluid is extremely high in order to maintain the properties of the rubber ring that seals the solenoid valve. This study deals with the rubber ring which is made from a fluoro-elastomer. The life cycle of the rubber ring was estimated by the relational expression of Arrhenius, and the solenoid valve was tested to confirm the sealing characteristics.