• Nuclear Engineering and Technology
• /
• 제47권2호
• /
• pp.212-218
• /
• 2015

We describe a comparative analysis of different tools used to assess safety-critical software used in nuclear power plants. To enhance the credibility of safety assessments and to optimize safety justification costs, $Electricit{\acute{e}}$ de France (EDF) investigates the use of methods and tools for source code semantic analysis, to obtain indisputable evidence and help assessors focus on the most critical issues. EDF has been using the PolySpace tool for more than 10 years. Currently, new industrial tools based on the same formal approach, Abstract Interpretation, are available. Practical experimentation with these new tools shows that the precision obtained on one of our shutdown systems software packages is substantially improved. In the first part of this article, we present the analysis principles of the tools used in our experimentation. In the second part, we present the main characteristics of protection-system software, and why these characteristics are well adapted for the new analysis tools. In the last part, we present an overview of the results and the limitations of the tools.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 1994년도 추계학술발표회 초록집
• /
• pp.141-145
• /
• 1994

A computer code for solving the 3-D time-dependent multigroup neutron diffusion equation by a coupled reactor kinetics method recently developed has been developed and for evaluating its applicability in CANDU transient analysis applied to a 3-D kinetics benchmark problem which reveals non-uniform loss of coolant accident followed by an asymmetric insertion of shutdown devices. The performance of the method and code has been compared with the CANDU design code, CERBERUS, employing a finite difference improved quasistatic method.

• 한국초전도ㆍ저온공학회논문지
• /
• 제10권1호
• /
• pp.62-66
• /
• 2008

The characteristic of the superconducting magnetic energy storage(SMES) system is faster response, longer life time, more economical, and environment friendly than other uninterruptible power supply(UPS) using battery. So, the SMES system can be used to develop methods for improving power quality where a short interruption of power could lead to a long and costly shutdown. Recently, cryogen free SMES has developed using BSCCO(Bismuth Strontium Calcium Copper Oxide) wire. We fabricated and tested the conduction cooling system for the 600 kJ class HTS SMES. The experiment was accomplished for the simulation coils. The simulation coils were made of aluminium, it is equivalent to thermal mass of 600 kJ HTS SMES coil. The coil is cooled with two GM coolers through the copper conduction bar. In this paper, we report that the test results of cool-down and heat loads characteristics of the simulation coils. The developed conduction cooling system adapted to 600 kJ HTS SMES system and cope with the unexpected sudden heat impact, too.

• 플랜트 저널
• /
• 제16권3호
• /
• pp.37-41
• /
• 2020

최근 노후화된 LNG선박의 증가, 선박가격 하락으로 중고 LNG선 재활용 가능성이 증대되고 있다.또한 노후발전소 대체관련 Needs가 늘고 있으며 가스생산량 증가 및 친환경 연료가 각광받고 있어 가스 발전플랜트 매력도도 상승하고 있다. 이에 본 연구에서는 중고 LNG선을 개조하여 LNG저장 및 발전플랜트 기능을 갖추게 하고 이밖에 재기화기능,벙커링 기능을 갖춘 복합기능 플랜트에 대한 기획연구를 수행하였다.이를 통해 노후 화력발전 중단,원전해체 등으로 인한 에너지 공백을 대체하고 국가 위기사태에 이동형 발전 플랜트를 긴급으로 투입가능해지며 대북 경협 등 정책에 새로운 대안으로 활용할 수 있다.

• Nuclear Engineering and Technology
• /
• 제51권3호
• /
• pp.676-682
• /
• 2019

After the Fukushima Daiichi accident, there has been an increasing preference for passive safety features in the nuclear power industry. Some passive safety systems require limited active components to trigger subsequent passive operation. Under very serious accident conditions, passive safety features could be rendered inoperable or damaged. This study evaluates (i) the performance and effectiveness of the passive safety features of iPOWER (innovative Power Reactor), and (ii) whether a severe accident condition could be reached if the passive safety systems are damaged, namely the case of heat exchanger tube rupture. Analysis results show that the reactor coolant system remains in the hot shutdown condition without operator actions or electricity for over 72 h when the passive auxiliary feedwater systems (PAFSs) are operable without damage. However, heat exchanger tube rupture in the PAFS leads to core damage after about 18 h. Such results demonstrate that, to enhance the safety of iPOWER, maintaining the integrity of the PAFS is critical, and therefore additional protections for PAFS are necessary. To improve the reliability of iPOWER, additional battery sets are necessary for the passive safety systems using limited active components for accident mitigation under such extreme circumstances.

• 에너지공학
• /
• 제8권4호
• /
• pp.525-532
• /
• 1999

한국형 차세대 원자로는 ABB-CE사의 System 80+의 설계개념을 근간으로 하여 표준화된 원자로의 계통설계를 추진하고 있다. 본 연구에서는 차세대 원자로 정지냉각계통의 운전시 요구되는 인허가 요건등제반 조건을 충족시킬 수 있는지를 해석하였다. 또한 운전시 필요한 열교환기의 유효면적과 원자로 기기냉각수 유량등 기본적인 설계자료를 산출하여 차후 차세대 원자로 정지냉각계통의 상세설계 업부를 수행하는데 필요한 기초자료를 제시하여 핵증기공급계통 (NSSS)의 기술개발을 이루는데 목적이있다. 차세대 원자로는 울진 3, 4호기 열출력 2.825MWth 에 비해 열출력이 4,000MWth 로 증가되어 정지냉각계통의 관련서례자료를 새로 산출해야하므로 정지냉각계통의 냉각능력을 평가하는 KDESCENT 전산코드를 이용하여 원자로 노심의 잔열과 정지냉각계통의 현열을 제거할 수 있는 최소 유량을 제시하였으며 주요 구성기기인 열교환기, 펌프, 밸브 및 기타 기기의 기능 및 정지냉각계통의 운전절차를 고찰하였다.

• 한국산업융합학회 논문집
• /
• 제21권6호
• /
• pp.265-271
• /
• 2018

DC-DC buck converter is a critical building block in the power management integrated circuit (PMIC) architecture for the portable devices such as cellular phone, personal digital assistance (PDA) because of its power efficiency over a wide range of conversion ratio. To ensure a safe operation, avoid unexpected damages and enhance the reliability of the converter, fully-integrated protection circuits such as over voltage protection (OVP), under voltage lock out (UVLO), startup, and thermal shutdown (TSD) blocks are designed. In this paper, these three fully-integrated protection circuit blocks are proposed for use in the DC-DC buck converter. The buck converter with proposed protection blocks is operated with a switching frequency of 1 MHz in continuous conduction mode (CCM). In order to verify the proposed scheme, the buck converter has been designed using a 180 nm CMOS technology. The UVLO circuit is designed to track the input voltage and turns on/off the buck converter when the input voltage is higher/lower than 2.6 V, respectively. The OVP circuit blocks the buck converter's operation when the input voltage is over 3.3 V, thereby preventing the destruction of the devices inside the controller IC. The TSD circuit shuts down the converter's operation when the temperature is over $85^{\circ}C$. In order to verify the proposed scheme, these protection circuits were firstly verified through the simulation in SPICE. The proposed protection circuits were then fabricated and the measured results showed a good matching with the simulation results.

• Nuclear Engineering and Technology
• /
• 제53권5호
• /
• pp.1436-1445
• /
• 2021

To obtain the dynamic characteristics of reactor secondary circuit under transient conditions, the system analysis program was developed in this study, where dynamic models of secondary circuit were established. The heat transfer process and the mechanical energy transfer process are modularized. Models of main equipment were built, including main turbine, condenser, steam pipe and feedwater system. The established models were verified by design value. The simulation of the secondary circuit system was conducted based on the verified models. The system response and characteristics were investigated based on the parameter transients under emergency shutdown and overload. Various operating conditions like turbine emergency shutdown and overspeed, condenser high water level, ejector failures were studied. The secondary circuit system ensures sufficient design margin to withstand the pressure and flow fluctuations. The adjustment of exhaust valve group could maintain the system pressure within a safe range, at the expense of steam quality. The condenser could rapidly take out most heat to avoid overpressure.

• 전력전자학회논문지
• /
• 제26권3호
• /
• pp.214-221
• /
• 2021

SiC MOSFETs require a faster and more reliable short-circuit protection circuit than conventional methods due to narrow short-circuit withstand times. Therefore, this research proposes a short-circuit protection circuit using a current-sensing circuit based on Rogowski coil. The method of designing the current-sensing circuit, which is a component of the proposed circuit, is presented first. The integrator and input/output filter that compose the current-sensing circuit are designed to have a wide bandwidth for accurately measuring short-circuit currents with high di/dt. The precision of the designed sensing circuit is verified on a double pulse test (DPT). In addition, the sensing accuracy according to the bandwidth of the filters and the number of turns of the Rogowski coil is analyzed. Next, the entire short-circuit protection circuit with the current-sensing circuit is designed in consideration of the fast short-circuit shutdown time. To verify the performance of this circuit, a short-circuit test is conducted for two cases of short-circuit conditions that can occur in the half-bridge structure. Finally, the short-circuit shutdown time is measured to confirm the suitability of the proposed protection circuit for the SiC MOSFET short-circuit protection.

• Journal of international Conference on Electrical Machines and Systems
• /
• 제2권4호
• /
• pp.460-465
• /
• 2013

Electrical equipments of nuclear power plant are divided into class 1E and non-class 1E. Electrical equipment and systems that are essential to emergency reactor shutdown, containment isolation, reactor core cooling, and containment and reactor heat removal, are classified as class 1E. batteries of nuclear power plant are divided into four channels, which are physically and electrically separate and independent. The battery bank of class 1E DC power system of the nuclear power plant use lead-acid batteries in present. The lead acid battery, which has a high energy density, is the most popular form of energy storage. Kt factor of lead-acid battery is used to determine battery size and it is one of calculatiing coefficient for capacity. this paper analyzes Kt factor of lead-acid battery for the DC power system of nuclear power plant. In addition, correlation between Kt parameter and peukert's exponent of lead-acid battery for nuclear plant are discussed. The analytical results contribute to optimize of determining size Lead-acid battery bank.