• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4263-4279
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• 2024

The small modular PWR (SMPWR) usually adopts integral design. Under severe accident, the system responses are different from those large PWRs. It is necessary to study the severe accident behavior of the SMPWR. A MELCOR model is developed for SMPWR and its steady-state results are in good agreement with the design values. Severe accidents induced by secondary pipeline break accidents are simulated, and no pressure relief measures are taken to keep the primary loop under high pressure. The mitigation effects of passive containment air cooling system (PAS) and passive cavity injection system (PCIS) are evaluated under different cases. The results show that under high pressure conditions, PCIS can effectively cool the lower head. The earlier the PCIS operates, the more significant the mitigation effect can be. In addition, PAS can effectively reduce the peak pressure and temperature in the containment. This study can provide a reference for the formulation of severe accident management guidelines on SMPWRs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• 한국가스학회지
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• 제23권2호
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• pp.9-16
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• 2019

울산, 여주 등 산업단지의 고압매설배관에서 발생할 수 있는 굴착공사 등 타 공사로 인한 중대사고의 발생빈도를 도시가스 매설 배관과 비교하여 FTA에 의해 기초사상(Basic event)을 도출하여 제시한다. 또한 굴착빈도, 순찰주기 등 배관손상 영향 인자를 관찰 및 분석하고, 이들 인자의 중요도와 민감도를 Risk 비교분석을 통해 구해봄으로써 고압가스매설배관의 안전성 향상에 기여한다.

• 한국해양공학회지
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• 제29권1호
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• pp.100-110
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• 2015

To meet the increasing demand for energy around the world, offshore and subsea energy development is constantly being conducted. This trend is accompanied by an increasing demand for pipeline installation, which brings numerous problems, including those related to accessibility, high pressure, and corrosion. Among these, corrosion is a primary factor in pipeline fractures, and can cause severe environmental and industrial damage. Hence, accurate corrosion assessment for corroded pipelines is very important. For this reason, the present study investigated the mechanical behavior of an idealized corroded subsea pipeline with an internal/external pressure load using the commercial FEA code ABAQUS. Then, the analysis result was compared with corrosion assessment codes such as ASME B31G, DNV RP F101, ABS. Finally, a fitness-for-service assessment was conducted.

• 한국해양공학회지
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• 제28권1호
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• pp.85-92
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• 2014

Offshore fields are increasingly important for the development of offshore resources due to the growing energy needs. However, an offshore field for oil and gas production has difficult development conditions, e.g., high temperature, high pressure, sweet/sour compositions of fluids, etc. Corrosion is one of the biggest issues for offshore pipeline engineering. In this study, a Corrosion Resistant Alloy (CRA) pipe for corrosion prevention was investigated through its global demand and trends, and three types of CRA pipelines were introduced with detailed explanations. The usefulness of CRA was also evaluated in comparison to a carbon steel pipeline in terms of the structural strength, cost, and other factors. Offshore pipeline engineering, including mechanical design and verification of the results through an installation analysis based on numerical software, was performed for the carbon steel type and solid CRA type. The results obtained from this study will be useful data for CRA pipeline designers and researchers.

• 한국해양환경ㆍ에너지학회지
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• 제19권1호
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• pp.52-61
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• 2016

대용량의 $CO_2$를 지중에 저장하기 위한 CCS(Carbon Capture and Storage)는 고압의 파이프라인 수송공정을 수반한다. 또한, 사고 및 유지보수와 같은 비정상상태가 발생할 경우 고압의 $CO_2$를 대기 중으로 방출시키는 감압공정이 필요하다. 본 연구에서는 고압 $CO_2$ 파이프라인에서의 감압현상을 수치해석적 방법을 이용하여 분석하였다. 수치계산 결과를 실험데이터와 비교분석함으로써 수치해석의 예측 능력을 검증하였다. 수치모델이 기체-액체 혼합 구간에서의 2상 감압현상을 잘 예측하였다. 그러나 초임계 액체 단상 감압과 기체 단상 감압현상에 대해서는 온도변화 등을 예측하는데 한계가 있음을 밝혔다.

• 에너지공학
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• 제26권3호
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• pp.90-96
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• 2017

지역난방 열수송관을 통해 중온수를 공급할 때 고압의 중온수로부터 열사용자 설비(지역난방 열교환기)를 보호하고 온도조절을 원활히 하고 유체의 원거리 공급을 위해 차압유량조절밸브를 통해 압력을 조절하거나 압력을 감소시키고 있다. 하지만, 고압 유체 사용에 따라 압력조절밸브에서 캐비테이션이 발생하여 잦은 고장 및 오작동을 유발하여 많은 문제가 발생하고 있으며, 사업자 및 사용자 모두에게 에너지 손실 및 민원 유발 등의 원인이 되고 있다. 이러한 문제를 해결하기 위해 연구 중인 1차측 차압유량조절밸브를 수력터빈으로 대체하여 차압에너지를 전기에너지로 변환하고, 전기를 2차측 펌프의 동력으로 활용하는 에너지 절감기술을 소개하고자 한다.

• 한국압력기기공학회 논문집
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• 제7권3호
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• pp.48-53
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• 2011

A PHE (Process Heat Exchanger) is a key component required to transfer heat energy of $950^{\circ}C$ generated in a VHTR (Very High Temperature Reactor) to the chemical reaction that yields a large quantity of hydrogen. A small-scale PHE prototype made of Hastelloy-X is being tested in a small-scale gas loop at Korea Atomic Energy Research Institute. In this study, as a part of the evaluation on the high-temperature structural integrity of the small-scale PHE prototype, we carried out macroscopic high-temperature structural analysis of the small-scale PHE prototype under the gas loop test conditions considering the pipeline stiffness.

• 열처리공학회지
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• 제27권5호
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• pp.235-241
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• 2014

Effects of rolling and cooling conditions on microstructures and mechanical properties of high-deformable pipeline steels were investigated in this study. Six kinds of pipeline steels were fabricated by varying rolling and cooling conditions, and their microstructures were analyzed by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. Tensile and Charpy impact tests were conducted on the steels in order to examine the mechanical properties. The steels rolled in the two-phase region showed better low-temperature toughness than those in the single-phase region due to the larger amount of ferrites having high-angle boundaries, although they have lower strength and absorbed energy. The steel rolled in single-phase and finish-cooled at higher temperature showed a good combination of high strength and good low-temperature toughness as well as excellent deformability of the lowest yield ratio and the highest uniform elongation because of the presence of fine ferrite and a mixture of various low-temperature transformation phases.

• 상하수도학회지
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• 제31권6호
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• pp.599-609
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• 2017

Desalination plants have been recently constructed in many parts of the world due to water scarcity caused by population growth, industrialization and climate change. Most seawater desalination plants are designed with a submarine pipeline for intake and discharge. Submarine pipelines are installed directly on the bottom of the water body if the bottom is sandy and flat. Intake is located on a low-energy shoreline with minimal exposure to beach erosion, heavy storms, typhoons, tsunamis, or strong underwater currents. Typically, HDPE (High Density Polyethylene) pipes are used in such a configuration. Submarine pipelines cause many problems when they are not properly designed; HDPE pipelines can be floated or exposed to strong currents and wind or tidal action. This study examines the optimal design method for the trench depth of pipeline, analysis of on-bottom stability and dilution of the concentrate based on the desalination plant conducted at the Pacific coast of Peru, Chilca. As a result of this study, the submarine pipeline should be trenched at least below 1.8 m. The same direction of pipeline with the main wind is a key factor to achieve economic stability. The concentrate should be discharged as much as high position to yield high dilution rate.