• Proceedings of the Korean Nuclear Society Conference
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• 1999.10a
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• pp.380.1-380
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• 1999

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.9-18
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• 1994

The engineered safeguards of Wolsung nuclear power plant unit 1 contain redundant systems of 2-out-of-3 logic which are not operating under normal conditions but are called upon to act when emergency conditions develop. To ensure their operability, the systems are periodically tested. In this work, we develop the unavailability formulae for 2-out-of-3 logic configurations which take into account the failure probability of the channels tested due to human error in the simultaneous testing scheme. We also develop the model for the probability that the reactor is tripped during the surveillance test due to either system failure or human error. We determined the optimal inspection periods of safety systems, taking into account both the unavailability of the safety system and the probability that the reactor is tripped during the surveillance test. We compared the results with the inspection periods currently used at Wolsung NPP Unit 1. As a result, the inspection periods obtained using a minimum human error (8.24 $\times$ 1$^{-6}$ ) are shorter than those currently used in Wolsung NPP unit 1 whereas the inspection periods obtained using a maximum human error are (4.44 $\times$ 10$^{-4}$ ) longer than those used in Wolsung NPP unit 1.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.73-78
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• 2003

Ultrasonic measurement is one of important technologies in the lift-time maintenance of nuclear poler plant. Ultrasonic inspection system is consisted of the operator, equipment and procedure. The reliability of ultrasonic inspection system is affected by its ability. The performance demonstration round robin was conducted to quantify the capability of ultrasonic inspection for in-service. The small number of teams who employed procedures that met or exceeded ASME Sec. XI Code requirements detected the piping of nuclear power plant with various cracks to evaluate the capability of detection and sizing. In this paper, the statistical reliability assessment of ultrasonic nondestructive inspection data using Monte Carlo simulation is presented. The results of the probability of detection (POD) analysis using Monte Carlo simulation are compared to these of logistic probability model. In these results, Monte Carlo simulation was found to be very useful to the reliability assessment f3r the small hit/miss data sets.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.8-14
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• 2013

Steam turbine blades and discs of nuclear power plants are one of the most highly stressed areas of turbine rotor, and periodic inspection of the blade roots is essential for monitoring integrity and preventing turbine failure. Ultrasonic technique is applied for volumetric inspection of blade root. However, the complexity of blade root geometry imposes challenges to inspection of blades and discs. Recently, phased array ultrasonic inspection technology is being applied to numerous power generation inspection applications including turbine rotor. The phased array ultrasonic technique requires customized inspection wedges which are generally necessary to generate effectively higher incident angle. But the usage of this wedge can cause access limitation for the lower stage blades of turbine because of the wedge front length. Therefore, the shear wave phased array probe which can generate high inspection angle without wedge is essentially necessary. In this study, feasibility study is conducted for the shear wave phased array ultrasonic probe application to blade and disc inspection. As results, the experimental results show that the shear wave phased array probe can detect the flaw and measure its size with reliable accuracy. Therefore if this shear wave phased array probe is applied to field inspection of blade and disc, more reliable inspection is expected for turbine having access limitation.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.05a
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• pp.511-512
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1024-1025
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• 2004

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.524.1-524
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• 2001

• Nuclear industry
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• v.3 no.5 s.15
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• pp.42-49
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• 1983

• Nuclear industry
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• v.5 no.4 s.26
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• pp.36-42
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• 1985

• Nuclear industry
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• v.5 no.12 s.34
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• pp.60-71
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• 1985