• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.3
• /
• pp.165-172
• /
• 2016

An experimental study of the thermal-hydraulic characteristics of passive safety systems (PSSs) was conducted using a system-integrated modular advanced reactor-integral test loop (SMART-ITL). The present passive safety injection system for the SMART-ITL consists of one train with the core makeup tank (CMT), the safety injection tank, and the automatic depressurization system. The objective of this study is to investigate the injection effect of the PSS on the small-break loss-of-coolant accident (SBLOCA) scenario for a 0.4 inch line break in the safety-injection system (SIS). The steady-state condition was maintained for 746 seconds before the break. When the major parameters of the target value and test results were compared, most of the thermal-hydraulic parameters agreed closely with each other. The water level of the reactor pressure vessel (RPV) was maintained higher than that of the fuel assembly plate during the transient, for the present CMT and safety injection tank (SIT) flow rate conditions. It can be seen that the capability of an emergency core cooling system is sufficient during the transient with SMART passive SISs.

• Nuclear Engineering and Technology
• /
• v.31 no.5
• /
• pp.476-485
• /
• 1999

In order to evaluate the gravity-injection capability to maintain core cooling after a loss-of-shutdown-cooling event during shutdown operation, the plant conditions of the Yong Gwang Units 3&4 were reviewed. The six cases of possible gravity-injection paths from the refueling water tank (RWT) were identified and the thermal-hydraulic analyses were performed using the RELAP5/MOD3.2 code. The core cooling capability was significantly dependent on the gravity-injection path, the RCS opening, and the injection rate. In the cases with the pressurizer manway opening higher than the RWT water level, the coolant was held up in the pressurizer and the system pressure continued increasing after gravity-injection. The gravity injection eventually stopped due to the high system pressure and the core was uncovered. In the cases with the injection path and opening on the same leg side, the core cooling was dependent on whether the water injected from the RWT passed the core region or not. However, in the cases with the injection path and opening on the different leg side, the system was well depressurized after gravity-injection and the core boiling was successfully prevented for a long-term transient. In addition, from the sensitivity study on the gravity-injection flow rate, it was found that about 54 kg/s of injection rate was required to maintain the core cooling and the core cooling could be provided for about 10.6 hours after event with that injection rate from the RWT. Those analysis results would provide useful information to operators coping with the event.

• Nuclear Engineering and Technology
• /
• v.51 no.3
• /
• pp.692-701
• /
• 2019

Recently, instrumentation and control (I&C) systems in nuclear power plants have undergone digitalization. Owing to the unique characteristics of digital I&C systems, the reliability analysis of digital systems has become an important element of probabilistic safety assessment (PSA). In a reliability analysis of digital systems, fault-tolerant techniques and their effectiveness must be considered. A fault injection experiment was performed on a safety-critical digital I&C system developed for nuclear power plants to evaluate the effectiveness of fault-tolerant techniques implemented in the target system. A software-implemented fault injection in which faults were injected into the memory area was used based on the assumption that all faults in the target system will be reflected in the faults in the memory. To reduce the number of required fault injection experiments, the memory assigned to the target software was analyzed. In addition, to observe the effect of the fault detection coverage of fault-tolerant techniques, a PSA model was developed. The analysis of the experimental result also can be used to identify weak points of fault-tolerant techniques for capability improvement of fault-tolerant techniques

• Journal of the Korea Safety Management & Science
• /
• v.6 no.4
• /
• pp.183-193
• /
• 2004

The injection mold industry has strong relationship with many other industries. In the injection mold industry, the harmonious collaboration of the order-making companies, the mold-making companies, and the molded-parts making companies, which are distantly located, is very important. In this study, a web-based collaboration system is developed for the purpose. It offers the criterion to select appropriate production companies. It also tries to minimize the production cost of the mold design by distributing and evaluating the design information. The developed system is constructed using various recent web-programming tools.

• Nuclear Engineering and Technology
• /
• v.41 no.8
• /
• pp.995-1004
• /
• 2009

The Advanced Power Reactor 1400 (APR1400) is an evolutionary advanced light water reactor (ALWR) based on the Optimized Power Reactor 1000 (OPR1000), which is in operation in Korea. The APR1400 incorporates a variety of engineering improvements and operational experience to enhance safety, economics, and reliability. The advanced design features and improvements of the APR1400 design include a pilot operated safety relief valve (POSRV), a four-train safety injection system with direct vessel injection (DVI), a fluidic device (FD) in the safety injection tank, an in-containment refueling water storage tank (IRWST), an external reactor vessel cooling system, and an integrated head assembly (IHA). Development of the APR1400 started in 1992 and continued for ten years. The APR1400 design received design certification from the Korean nuclear regulatory body in May of2002. Currently, two construction projects for the APR1400 are in progress in Korea.

• Journal of Biosystems Engineering
• /
• v.21 no.2
• /
• pp.155-166
• /
• 1996

A direct injection sprayer was designed using the concepts of injection mixing and total flow control, flowrate-based system compensating for the variation of forwarding speed. A metered rate, proportionally to the actual diluent flow rate, of a tracer chemical was injected directly into the diluent stream. The injection of chemical may improve the precision and safety of chemical application process. The control system was evaluated for the variables of the control interval, tolerances and sensitivities of flow regulation valve and injection pump. Performance of the system was assessed as that the response time of flow rate, response time of injection rate, absolute steady state error, and the coefficient of variance(C.V.) of concentration were 8.5 and -0.53 seconds, 0.067 lpm(0.8%) and 3.15%, respectively, at optimal parameters of control interval of 1.0 sec, fast sensitivity of flow regulation valve, medium sensitivity of injection pump and medium tolerance of flow rate. Performance of the system can be improved by increasing the sensitivity of flow regulating valve and employing a high resolution velocimeter, such as Doppler radar.

• Journal of the Korean Society of Safety
• /
• v.10 no.4
• /
• pp.22-35
• /
• 1995

In this paper, an electronic control unit is developed using 16bit microcomputer for automobile engine. This system incorporate AFS(Air Flow Sensor) of Hot Wire type, DIS(Direct Ignition System), ISC(Idle Speed Control) system, CAS(Cranke Angle Sensor) and other peripheral device. This system includes hardware and software to facilitate precision control of both fuel injection and ignition timing. Especially, this controller consists of position signal(180 teeth) and 4 REF signals. Present system has maximum $720^{\circ}CA$ delay. But this system has maximum $180^{\circ}CA$. Thus, this system is able to precision control both fuel injection and ignition timing.

• Proceedings of the Safety Management and Science Conference
• /
• 2010.04a
• /
• pp.189-197
• /
• 2010

Recently, industrial business environments have rapidly changed and face severe competitive challenges. The effective inventory system enables to product and deliver the products quickly for meeting due date of customer's order in this environment. This study have developed a web-based inventory system framework using RFID for a plastic injection molding industry. The system analysis inventory problem issues such as inventory planning, warehouse assignment. In this study, web-based inventory system using Java language is proposed and implemented. As the result of implementation of the system, we expected that it manages to inventory planning continually and systematically.

• Journal of the Korea Safety Management & Science
• /
• v.12 no.3
• /
• pp.177-182
• /
• 2010

Industrial business environments have rapidly changed and face severe competitive challenges. The effective inventory system enables to product and deliver the products quickly for meeting due date of customer's order in this environment. This study have developed a web-based inventory system using RFID for an injection molding industry. The system analysis inventory problem issues such as inventory planning, warehouse assignment and assist to develop production scheduling. In this study, web-based inventory system using Java language and RFID technology is proposed and implemented. As the result of implementation of the system, we expected that it manages to inventory planning continually and systematically.

• Nuclear Engineering and Technology
• /
• v.41 no.7
• /
• pp.921-928
• /
• 2009

As part of an evaluation for an in-vessel severe accident management strategy, a coolant injection into the reactor vessel under depressurization of the reactor coolant system (RCS) has been evaluated in detail using the SCDAP/RELAP5 computer code. A high-pressure sequence of a small break loss of coolant accident (SBLOCA) has been analyzed in the Optimized Power Reactor (OPR) 1000. The SCDAP/RELAP5 results have shown that safety injection timing and capacity with RCS depressurization timing and capacity are very effective on the reactor vessel failure during a severe accident. Only one train operation of the high pressure safety injection (HPSI) for 30,000 seconds with RCS depressurization prevents failure of the reactor vessel. In this case, the operation of only the low pressure safety injection (LPSI) without a HPSI does not prevent failure of the reactor vessel.