• 한국유체기계학회 논문집
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• 제10권1호
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• pp.41-48
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• 2007

The effect of the upstream flow conditions on the disc stability of the swing check valves was investigated at various upstream flow disturbance sources and distances from the tested check valves. The experimental loop was designed and installed to measure the disc positions, disc back stop load, and differential pressure at flow velocities lot 3 inch and 6 inch swing check valves. The selected disturbance sources are elbow and globe valve. The effect of the disc fluctuation is different depending on the type of disturbance and the distance between the disturbance and the check valve. Disturbances generated by elbow and globe valve located upstream from check valve create greater and more violent disc motion than uniform flow.

• 한국소음진동공학회논문집
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• 제12권1호
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• pp.36-41
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• 2002

The cause and the elimination method for the chattering phenomena were investigated in a check valve attached to the exit of an auxiliary cooling water pump in a Korean nuclear powerplant. From the site experiment and the numerical calculation, the incident angle of the disk was so small that it was not able to produce the sufficient lifting force to overcome the gravitational component of the disk weight. Moreover, it turned out that the installation position was not symmetric for the secondary vortical flow generated inside the elbow so that the flow structure had strongly unstable flow characteristics. From this study, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and the installation position of the calve body.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.407-412
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• 2008

원자력발전소의 안전성 확보를 위해서, 설비의 유지 관리 기법은 고장이 발생했을 때 조치하는 고장정비에서부터 고장을 미연에 방지하기 위한 예방정비, 예측정비 그리고 상태기반정비로 진행되어 가고 있다. 국내 원자력발전소에서는 고장정비와 예방 정비가 적용되고 있으며, 예측정비와 상태기반정비에 대한 연구가 수행되고 있다. 본 논문에서는 모터구동밸브, 공기구동밸브, 역지밸브 그리고 펌프에 대한 예방정비 현황과 기술 개발 동향에 대해 살펴보았다.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 2005년도 춘계 학술발표회
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• pp.223-228
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• 2005

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.178.2-178
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• 2002

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 요약집 춘계학술발표대회
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• pp.221-221
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• 2004

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2004년도 요약집 춘계학술발표대회
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• pp.91.2-91.2
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• 2004

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.69-73
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• 2015

The study investigated effects of residual stresses and Charpy impact energy on brittle fractures of the butt weld between the valve and the piping, and of the valve body in nuclear power plants via a linear elastic fracture mechanics approach in the ASME B&PV Code, Sec.XI and finite element analysis. Weld residual stress in a butt weld between close check valve and piping, and residual stress in the valve due to casting process were assumed to be proportional to yield strength of base metal. Operating stresses in the butt weld and the valve body were calculated using approximate engineering formulae and finite element analysis, respectively. Applied stress intensity factors were calculated by assuming postulated cracks with specific sizes and then by substituting the residual stresses and the operating stresses into engineering formulae presented in the ASME B&PV Code, Sec.III. Plane strain fracture toughness was derived by using a correlation between Charpy V-notch impact energy and fracture toughness. Structural integrity of the weld and the body against brittle fracture was assessed by using the applied stress intensity factors, plane strain fracture toughness and the linear elastic fracture mechanics approach. As a result, it was identified that the structural integrity was maintained with decreasing the residual stress levels and increasing the Charpy V-notch impact energy.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.881-886
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• 2003

In spite of its simple design, structure and operating mechanism, swing check valves are one of the critical components which adversely affect the safety of the nuclear power plants if they fail to function properly. Therefore, it is important to evaluate the performance condition of the swing check valves in safety-related systems. The performance characteristics of swing check valves include opening characteristics, the minimum required flow velocity, the pressure drop at design flow, the disc stability, and the effect of the upstream disturbances. Among factors to identify the performance of a swing check valve, a method to evaluate the opening characteristics and the minimum required flow velocity, which guarantees to fully open the disc and hold the disc without motion, are presented to determine the operating region of the swing check valve, such as stable, tapping, or oscillation. Based on the determined operating region and opening characteristics, the simple methods of wear and fatigue analyses of the specific parts of the valve are also described.

• 한국유체기계학회 논문집
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• 제8권6호
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• pp.15-25
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• 2005

Check valves playa vital role in the operation and protection of nuclear power plants. Check valves failure in nuclear power plants often lead to a plant transient or trip. The analysis of historical failure data gives information on the populations of various types of check valves, the systems they are installed in, failure modes, effects, methods of detection, and the mechanisms of the failures. A majority of check valve failures are caused by improper application. The experimental apparatus is designed and installed to measure the disc positions with flow velocity, Vopen and Vmin for 3 inch and 6 inch swing check valves. The minimum flow velocity necessary to just open the disc at a full open position is referred to as Vopen, and Vmin is defined as the minimum velocity to fully open the disc and hold it without motion. In the experiments, Vmin is determined as the minimum flow velocity at which the back stop load begins to increase after the disc is fully opened or the oscillation level of disc is reduced below $1^{\circ}$. The results show that the Vmin velocities for 3 inch and 6 inch swing check valves are about 27.3% and 17.5% higher than the Vopen velocities, respectively.