• Nuclear Engineering and Technology
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• 제55권6호
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• pp.2263-2275
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• 2023

In general, an internal fire events probabilistic safety assessment (PSA) model is quantified by modifying the pre-existing internal event PSA model. Because many pieces of equipment or cables can be damaged by a fire, a single fire event can lead to multiple internal events PSA initiating events (IEs). Consequently, when the fire events PSA model is quantified, inappropriate minimal cut sets (MCSs), such as duplicate MCSs, may be generated. This paper shows that single quantification of a hypothetical single-top fire event PSA model may generate the following four types of inappropriate MCSs: duplicate MCSs, MCSs subsumed by other MCSs, nonsense MCSs, and MCSs with over-counted fire frequencies. Among the inappropriate MCSs, the nonsense MCSs should be addressed first because they can interfere with the right interpretation of the other MCSs and prevent the resolution of the issues related to the other inappropriate MCSs. In addition, we propose a resolution process for each of the issues caused by these inappropriate MCSs and suggest an overall procedure for resolving them. The results of this study will contribute to the understanding and resolution of the inappropriate MCSs that may appear in the quantification of fire events PSA models.

• Nuclear Engineering and Technology
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• 제43권3호
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• pp.271-278
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• 2011

When performing fire PSA in a nuclear power plant, an event mapping method, using an internal event PSA model, is widely used to reduce the resources used by fire PSA model development. Feasible initiating events and component failure events due to fire are identified to transform the fault tree (FT) for an internal event PSA into one for a fire PSA using the event mapping method. A surrogate event or damage term method is used to condition the FT of the internal PSA. The surrogate event or the damage term plays the role of flagging whether the system/component in a fire compartment is damaged or not, depending on the fire being initiated from a specified compartment. These methods usually require explicit states of all compartments to be modeled in a fire area. Fire event scenarios, when using explicit identification, such as surrogate or damage terms, have two problems: (1) there is no consideration of multiple fire propagation beyond a single propagation to an adjacent compartment, and (2) there is no consideration of simultaneous fire propagations in which an initiating fire event is propagated to multiple paths simultaneously. The present paper suggests a fire propagation equation to identify all possible fire event scenarios for an explicitly treated fire event scenario in the fire PSA. Also, a method for separating fire events was developed to make all fire events a set of mutually exclusive events, which can facilitate arithmetic summation in fire risk quantification. A simple example is given to confirm the applicability of the present method for a $2{\times}3$ rectangular fire area. Also, a feasible asymptotic approach is discussed to reduce the computational burden for fire risk quantification.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2795-2798
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• 2003

본 논문에서는 국내에서 개발하고 있는 과학로켓용 발사통제시스템(FCS, Fire Control System)의 시퀀스제어의 처리 영역을 PLC 시스템을 사용하여 구현하였다. 프로세서의 이중화를 통하여 Hot Backup 시스템을 구축하고 ControlNet 네트워크［l］［2］를 기반으로 하는 프로세서와 I/O 간의 통신을 이용하였다. 먼저 로켓 발사통제시스템의 개요 및 주요 임무에 대하여 설명하고 기존에 사용된 발사통제시스템 구성을 분석하였다. PLC 시스템의 개요와 CPU 동작 내용 그리고 ControlNet 통신방식에 대하여 설명하고 프로세서를 이중화한 시스템을 제안하였다. 또한 이중화된 프로세서의 Switchover［2］방법을 알아보고 이러한 조건에 따른 PLC 시스템을 응용한 발사 통제시스템을 구성하여 이를 위해 작성된 시스템 운용 Ladder Diagram 프로그램에 대한 기술을 논하였다. 개발된 PLC 시스템의 구성을 제시하고 발사체 및 각종 지원시설과 연계한 시험을 통하여 성능을 검증하였다.

• 문화기술의 융합
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• 제9권5호
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• pp.737-745
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• 2023

본 논문은 열화상 이미지를 활용하여 배전반 화재 발생을 감지하기 위한 인공지능 모델을 개발하는 연구에 대해 다룬다. 연구의 목표는 수집한 열화상 이미지를 전처리하여 객체 탐지 모델에 적합한 데이터로 가공하고, 이를 이용하여 배전반 내 화재 발생 여부를 판단하는 모델을 설계하는 것이다. 연구에서는 AI-HUB의 산업단지 내 학습용 열화상 이미지 데이터를 활용하였으며, CNN 기반 딥러닝 객체 검출 알고리즘 중 대표적인 모델인 Faster R-CNN과 RetinaNet을 사용하여 모델을 구축하고 두 개의 모델을 비교 분석하여 최적의 모델을 제안하고 있다.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.719-728
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• 2015

Following the Fukushima accident, a special safety inspection was conducted in Korea. The inspection results show that Korean nuclear power plants have no imminent risk for expected maximum potential earthquake or coastal flooding. However long- and short-term safety improvements do need to be implemented. One of the measures to increase the mitigation capability during a prolonged station blackout (SBO) accident is installing injection flow paths to provide emergency cooling water of external sources using fire engines to the steam generators or reactor cooling systems. This paper illustrates an evaluation of the effectiveness of external cooling water injection strategies using fire trucks during a potential extended SBO accident in a 1,000 MWe pressurized water reactor. With regard to the effectiveness of external cooling water injection strategies using fire engines, the strategies are judged to be very feasible for a long-term SBO, but are not likely to be effective for a short-term SBO.

• 한국화재소방학회논문지
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• 제27권4호
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• pp.47-55
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• 2013

최근 소방안전 서비스는 위험의 사전방지와 일상생활에서 느끼는 생활안전 업무까지 확대되고 있다. 본 연구는 생활안전의 이론적 탐색과 119생활안전대의 실태분석을 바탕으로 소방공무원과 경기도민을 대상으로 설문조사의 결과를 토대로 소방조직의 효과적인 생활안전서비스 방안을 제시하는데 있다. 연구의 결과 지역사회의 사회적 자본 활용, 유관기관 협력관계 구축과 시민의 지지 확보, 다조직간의 협력, 긴급신고와 비긴급신고 구분, 생활안전 소방서비스의 사회안전망 역할 등을 제안하였다.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.410-423
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• 2019

Fire suppression using a water mist nozzle directly above an n-Heptane pool in a fire compartment with a door opening was numerically investigated using the Fire Dynamics Simulator (FDS) for the purpose of application in nuclear power plants. Input parameters for the numerical simulation were determined by experimental measurements. Water mist was activated 10 s after the fire began. The sensitivity analysis was conducted for three input parameters: total number of cubic cells of 6032-2,926,400, droplets per second of 1000-500,000, and extinguishing coefficient of 0-100. In a new simple calibration method of this study, the extinguishing coefficient yielding the fire suppression time closest to that measured by experiments was found for use as the FDS simulation input value. When the water mist jet flow made contact with the developed fire, the heat release rate instantaneously increased, and then rapidly decreased. This phenomenon occurred with a displacement of the flame near the liquid fuel pool. Changing the configuration of the door opening with different aspect ratios and opening ratios had impact on the maximum value of the heat release rate due to the flame displacement.

• Nuclear Engineering and Technology
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• 제54권5호
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• pp.1652-1656
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• 2022

Fire tests were conducted on cables using fire-retardant paint employed in nuclear power plants that transmit electrical power, control and instrument signals. The failure criteria of various power and control cables coated with fire retardant coating at three different coating thicknesses (~0.5 mm, 1.0 mm & 1.5 mm) were studied under direct flame test using Container Fire Test Facility (CFTF) based on standard tests for bare cables. A direct flame fire test was conducted for 10 min with an LPG ribbon burner rated at ten by fixing the cable samples in a vertical cable track. Inner sheath temperature was measured until ambient conditions were achieved by natural convection. The cables are visually evaluated for damage and the mass loss percentage. Cable functionality is ascertained by checking for electrical continuity for each sample. The thickness of cable coating on fire exposure is also studied by comparing the transient variation of inner sheath temperature along the Cable length. This study also evaluated the adequacy of fire-retardant coating on cables used for safety-critical equipment in nuclear power plants.

• International Journal of Advanced Culture Technology
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• 제7권3호
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• pp.92-96
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• 2019

This study analyzes the problems of fire qualification information websites and job search websites due to incomplete information in the job search process and suggests an improvement plan. It has been confirmed that the main reason for the cost of job searching is incomplete information required for a job search and job search through existing analysis. As a result, it is suggested to construct a smooth information system for economic entities and to provide easy access to information by mitigating the incompleteness of information. Based on this, analysis of the problems of Korean qualifications in the firefighting realm reveals that there is a qualification holder information and a job information site, and a qualification holder management system is established but only information of either qualification acquisition information or employment information is provided. In addition, it is easy to access information through a qualification acquisition information and employment information site via the Internet, but there are inconveniences that qualification acquisition information and employment information are dualized. In order to improve this, it is necessary to build a new customized integrated qualification management system that covers existing Q-net qualification acquisition information and worknet employment information.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2604-2612
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• 2023

Spent nuclear fuel and long-lived radioactive waste must be carefully handled before disposing them off to a geological repository. After the pre-storage period in water pools, spent nuclear fuel is stored in casks, which are widely used for interim storage. Interim storage in casks is very important part in the whole cycle of nuclear energy generation. This paper presents the results of the numerical study that was performed to evaluate the thermal behavior of a metal-concrete CONSTOR RBMK-1500 cask loaded with spent nuclear fuel and placed in an open type interim storage facility which is under fire conditions (steady-state, fire, post-fire). The modelling was performed using the ANSYS Fluent code. Also, a local sensitivity analysis of thermal parameters on temperature variation was performed. The analysis demonstrated that the maximum increase in the fuel load temperatures is about 10 ℃ and 8 ℃ for 30 min 800 ℃ and 60 min 600 ℃ fires respectively. Therefore, during the fire and the post-fire periods, the fuel load temperatures did not exceed the 300 ℃ limiting temperature set for an RBMK SNF cladding for long-term storage. This ensures that fire accident does not cause overheating of fuel rods in a cask.