• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1995년도 추계학술발표회논문집(2)
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• pp.509-516
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• 1995

The uncertainty analysis for the in-vessel steam explosion during severe accidents at a nuclear power plant is performed using a probabilistic approach. This approach consists of four steps; 1) screening, 2) quantification of uncertainty 3) propagation of uncertainty, and 4) output analysis. And the specific methods which satisfy the sub-objectives of each step are prepared and presented. Compared with existing ones, the unique feature of this approach is the improved estimation of uncertainties through quantification, which ensures the defensibility of the resultant failure probability distributions. Using the approach, the containment failure probability due to in-vessel steam explosion is calculated. The results of analysis show that 1) pour diameter is the most dominant factor and slug condensed phase fraction is the least and 2) fraction of core molten is the second most dominant factor, which is identified as distinct feature of this study as compared with previous studies.

• Nuclear Engineering and Technology
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• 제17권1호
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• pp.53-67
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• 1985

중대 노심사고는 아직 Design Basis Accident에 포함되지 않고 있으나, 극히 적은 사고 확률을 가지는 반면 사고 후 영향이 큼으로해서 원자력발전소의 전반적 위험 평가에 중요한 요인중의 하나가 되고 있다. 중대 노심사고시 격납용기 손상에 관련된 물리현상들은 Steam Explosion, Debris Bed Coolability, Hydrogen Burning, Steam Spike와 Core-Concrete Interaction 등이며, 각각의 현상에 대한 좀 더 나은 이해를 위해 현재 이루어지고 있는 연구들에 대한 개략적 설명을 시도 하였다.

• Nuclear Engineering and Technology
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• 제39권4호
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• pp.237-248
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• 2007

Sodium-cooled fast reactor is considered in France as a potential candidate for a prototype of 4th generation system to be built by 2020. A detailed working program has been launched recently to identify by 2012 the potential improvement tracks for later industrial development of these reactors. The goals for innovation are first identified: Progress of the safety with a special attention to severe accidents risk minimization and mitigation (defense in depth approach); Economic competitiveness of the system mainly by reducing the capital cost, the investment risks by enhancing in service inspection and repair capacities, and raising the availability; Sustainability with fissile material management while reducing the proliferation risk; capacity for long-lived waste transmutation.

• Nuclear Engineering and Technology
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• 제45권4호
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• pp.459-468
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• 2013

During a station blackout (SBO), the initiating event is a loss of Class IV and Class III power, causing the loss of the pumps, used in systems such as the primary heat transporting system (PHTS), moderator cooling, shield cooling, steam generator feed water, and re-circulating cooling water. The reference case of the SBO case does not credit any of these active heat sinks, but only relies on the passive heat sinks, particularly the initial water inventories of the PHTS, moderator, steam generator secondary side, end shields, and reactor vault. The reference analysis is followed by a series of sensitivity cases assuming certain system availabilities, in order to assess their mitigating effects. This paper also establishes the strategies to mitigate SBO accidents. Current studies and strategies use the computer code of the Integrated Severe Accident Analysis Code (ISAAC) for Wolsong plants. The analysis results demonstrate that appropriate strategies to mitigate SBO accidents are established and, in addition, the symptoms of the SBO processes are understood.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.3102-3113
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• 2023

Following the Fukushima nuclear disaster, the simulation of accidents in the spent fuel pool has become more noticeable. Despite the low amount of decay heat power, the consequences of the accidents in a spent fuel pool (SFP) can be severe due to the high content of long-lived radionuclides and lack of protection by the pressure vessel. In this study, the loss-of-cooling accident (LOFA) for the VVER-1000/V446 spent fuel pool is simulated by employing RELAP5 and MELCOR 1.8.6 as the best estimate and severe accident analysis codes, respectively. For two cases with different total power levels, decay heat of spent fuels is calculated by ORIGEN-II code. For modeling SFP of a VVER-1000, a qualified nodalizations are considered in both codes. During LOFA in SFP, the key sequences such as heating up of the pool water, boiling and reducing the water level, uncovering the spent fuels, increasing the temperature of the spent fuels, starting oxidation process (generating Hydrogen and extra power), the onset of fuel melting, and finally releasing radionuclides are studied for both cases. The obtained results show a reasonable consistency between the RELAP5 and MELCOR codes, especially before starting the oxidation process.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4585-4600
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• 2022

A pool scrubber is often used as a wet-type design to mitigate the consequence of a severe nuclear accident. While studies indicated higher decontamination performance of a deeper pool, utilizing a very tall pool can be problematic due to potential structural stability and water backflow issues. This study proposes, as an alternative to a single pool system, a pool scrubber system composed of serially connected multiple pools with lower heights. Since large fraction of aerosol removal takes place in the injection region, serially connected pool scrubber system is expected to enhance the overall decontamination capability of a pool scrubber system. To support the analysis of the proposed system's decontamination capability, a new computer model was developed in the study to describe the bubble size dependent effect on aerosol removal including the effect of pool residence time. The accuracy of the new model was examined against experimental data for its validation. The proposed scrubber system composed of serially connected multiple shorter pools is found to have much improved decontamination performance over the current single pool system design.

• 한국안전학회지
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• 제32권1호
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• pp.47-52
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• 2017

Chemical accidents occur by a variety of causes and aspects. Accident preparedness substances (APS) are defined by toxic chemicals highly likely to cause accidents due to their high acute toxicity, explosiveness or likely to cause severe damage where a chemical accident occurs among the chemicals. APS is designated and announced by Presidential Decree. However, chemical accidents occurred for recent 7 years were arisen mainly from non-accident preparedness substances, and only 24 species were included as chemical accident trigger among total 69 APS. In addition, APS were designated in 2014 and the list has not been updated since then although it needs to be amended in several aspects. Accordingly, this study analyzes the necessity of modification of APS management, and presents improved plans.

• 한국농공학회논문집
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• 제54권6호
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• pp.121-131
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• 2012

Many of the falling which is the number one risk factor in lethal accidents in construction could have been prevented if the right activity or supervising had been taken in time. All other measures do not preventive the fall, but rather intercept the fallen itself or preventive severe injury. The most common and the bets measures on the preventive measures are guardrails which are to be worn on the site. Workers always exposed the risk of serious accidents induced by causal effects related with environments around construction sites. In order to represent how to decrease the risk of workers, this study was accomplished with a number of interview with experienced site director, cheief of instructors, workers. And the questionaire survey (2012. 5~2012. 10) were used to make proposed policies which are expected to reduce critical disastrous accidents and strength authorized limits of director's management automatically.

• 한국항해항만학회지
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• 제26권5호
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• pp.549-554
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• 2002

국가는 재난에 대비한 범국가적 해양 구난방제체제 수림이 절실히 요구되고 있다. 그러나 우리나라는 구난방제 시설과 기술이 부족한 관계로 대형 해양사고 발생시 그 처리를 외국기술에 의존하는 형편이다. 이로 인해 가장 중요한 사고초기에 적절한 대처를 못하여 사고의 피해를 크게 확산시킬 우려가 상존하고 있다. 이에 이 논문에서는 해양사고가 발생할 경우 신속하고 효과적인 구난방제작업을 할 수 있도록 구난방제체제의 기반조성과 시설투자, 기술개발 및 능력 배양 등 다각적인 방안을 제시하였다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.190-190
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• 2001