• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.7-12
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• 2006

In this paper, a new evaluation scheme is suggested to estimate load-carrying capacities of wall thinned pipes. At first, computational fluid dynamics analyses employing steady-state and incompressible flow are carried out to determine pressure distributions in accordance with conveying fluid. Then, the variational pressures are applied as input condition of structural finite element analyses to calculate local stresses at the deepest point. The efficiency of proposed scheme was proven from comparison to conventional analyses results and it is recommended to consider the fluid structure interaction effect for exact integrity evaluation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.313-318
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• 2012

In CANDU, feeder pipes supply heavy water to pressure tube and steam generator. Under service conditions, Flow-Accelerated Corrosion (FAC) produces local wall-thinning in the feeder pipes. The wall-thinning in these pipes affects the integrity of the piping system, as verified in previous research. This paper provides limit loads for wallthinned feeder pipes with $45^{\circ}$ and $60^{\circ}$ bend angles, and proposes an equation that predicts the limit loads for wallthinned feeder pipes with arbitrary bend angles. On the basis of finite element limit analyses, limit loads are obtained for wall-thinned feeder pipes under in-plane bending and internal pressure. There are two cases of in-plane bending: the in-plane closing direction and the in-plane opening direction. The material is considered the effect of the large deformation, so an elastic-perfectly-plastic material is assumed in the calculations.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.127.2-127
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• 2001

• Nuclear industry
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• v.7 no.4 s.50
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• pp.86-87
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• 1987

미국원자력규제위원회(NRC)의 조사에 의하면 배관파단의 원인은 파단부 부근의 배관내면이 심하게 감육하고 있으며 원자로 트?후의 2차계의 압력변동에 견디지 못했기 때문이라고 보여지고 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 2002.10a
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• pp.401.1-401
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• 2002

• Proceedings of the Korean Magnestics Society Conference
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• 2016.11a
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• pp.90-91
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• 2016

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.807-812
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• 2001

This paper represents the wall thinning analysis results for secondary side piping of two types of domestic nuclear power plants based on the DB establishment and F AC analysis study for NPP secondary system piping. CHECWORKS code utilized in this study has been applied world widely to wall thinning analyses for secondary side piping and its reliability has also been proved. The predicted wear rates for several piping systems of a pressurized water reactor NPP are compared with those of a pressurized heavy water reactor NPP and with the measured wear rates. On the basis of comparison results of the predicted and measured wear rates, the analysis results can be effectively applied to the development of a standard thinned pipe management program targeted all domestic nuclear power plants.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.4
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• pp.331-338
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• 2008

Ultrasonic testing for welds is widely used to ensure the integrity of facilities in NPPs. Automated ultrasonic testing(AUT) is more consistent than the manual ultrasonic testing(MUT). It can scan welded parts, examines the scanned images, and saves the results as data files. AUT in NPPs is making use of commercial systems, and there has been some difficulties in calibration of the system. An AUT system is developed. It comprises of pulser/receiver, scanner and a control program(SonicWizard). The performance demonstration for piping welds in NPPs and the piping wall thickness measurement on site were conducted to verify this system. The test results of the ultrasonic testing system developed is satisfactory and effective.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.31-39
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• 2015

Pipe wall-thinning by flow-accelerated corrosion (FAC) and various types of erosion is a significant and costly damage phenomenon in secondary piping systems of nuclear power plants (NPPs). Most NPPs have management programs to ensure pipe integrity due to wall-thinning that includes periodic measurements for pipe wall thicknesses using ultrasonic tests (UTs). Nevertheless, thinning evaluations are not easy because the amount of thickness reduction being measured is often quite small compared to the accuracy of the inspection technique. U.S. Electric Power Research Institute (EPRI) had proposed Total Point Method (TPM) as a thinning occurrence evaluation method, which is a very useful method for detecting locally thinned pipes or fittings. However, evaluation engineers have to discern manually the measurement data because there are no numerical algorithm for TPM. In this study, numerical algorithms were developed based on non-parametric and parametric statistical method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.156-162
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• 2006

Pipe thinning is one of the major issues for the structural fracture of pipes of nuclear power plants. Therefore a method to inspect a large area of piping systems quickly and accurately is needed. In this paper, we proposed the method for monitoring pipe thinning. Our basic idea come from that a group velocity of impact wave is different as wall thickness. If the group velocity is measured, wall thickness can be estimated. To obtain the group velocity, time-frequency analysis is used. This is because an arrival time difference can be measured easily in time-frequency domain rather than time domain. To test the performance of this technique, experiments have been performed for a plate and U type pipe. Results show that the proposed technique is quite powerful in the monitoring pipe thinning.