• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.3
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• pp.1-6
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• 2012

The containment Integrated Leakage Rate Testing(ILRT) of nuclear power plants in Korea is performed in accordance with NSSC(Nuclear Safety and Security Commission) code 2012-16 and ANSI/ANS 56.8-1994. Nuclear power plants in Korea and the United States are to apply same test criteria, ANSI/ANS 56.8-1994, except type A testing time. NPPs in Korea apply 24 hours according to NSSC code 2012-16, but NPPs in United States apply 8 hours according to 10CFR50 App. J for type A test. So, there are many difficulties in order to perform ILRT in Korea. In this study, I review the impact on the ILRT results and the effect of ILRT due to type A testing time. The future, we will continue study to enhance the test reliability and improve these problems.

• Journal of the Earthquake Engineering Society of Korea
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• v.19 no.1
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• pp.21-28
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• 2015

The nuclear accident due to the recent earthquake in Japan has triggered awareness of the importance of safety with regard to nuclear power plants (NPPs). An earthquake is one of the most important parameters which governs the safety of NPPs among external events. Application of a base isolation system for NPPs can reduce the risk for earthquakes. At present, a soil-structure interaction (SSI) analysis is essential in the seismic design of NPPs in consideration of the ground structure interaction. In the seismic analysis of the base-isolated NPP, it is restrictive to consider the nonlinear properties of seismic isolation devices due to the linear analysis of the SSI analysis programs, such as SASSI. Thus, in this study, SSI analyses are performed using an iterative approach considering the material nonlinearity of the isolators. By performing the SSI analysis using an iterative approach, the nonlinear properties of isolators can be considered. The difference between the SSI analysis results without iteration and SSI with iteration using SASSI is noticeable. The results of the SSI analysis using an effective linear (non-iterative) approach underestimate the spectral acceleration because the effective linear model cannot consider the nonlinear properties of isolators. The results of the SSI analysis show that the horizontal response of the base-isolated NPP is significantly reduced.

• Journal of the Ergonomics Society of Korea
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• v.32 no.1
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• pp.47-58
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• 2013

Objective: The aim of this study is to review the job stress measurement for applying in nuclear power plants(NPPs). Background: The standard and guideline to evaluate and manage the job stress is insufficient in NPPs. Although job stress might have a negative effect on task performance particularly it can be related with human error in NPPs. Method/Results: This paper considered the objective and subjective stress measurements. One of the questionnaire(Korean Occupational Stress Scale) and the experiment method was investigated to apply in NPPs. KOSS was analyzed about the inter item consistency and correlation with the workload, and relative importance. In the objective evaluation considered the experiment method for the physical and mental job stress and analyzed from the phased point of view. Conclusion/Application: The measurement and criteria to evaluate job stress for operators must be complemented on the job characters and environments in NPPs. This study may support to confirm and manage the job stress in NPPs. The study of more specific methodology on job stress in NPPs is required on the basis of this paper.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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• pp.300-305
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• 2013

LOOP(Loss of Offsite Power) and SBO(Station Blackout) events have been occurring in nuclear power plants should be reviewed and be controlled on important electrical equipments by professional engineer to prevent and to safety improvement from safety assessment and reliability analysis report. LOOP and SBO occasionally happened by internal or external causes. This paper contained that LOOP frequency in the United States NPPs and in the domestic NPPs have compared and analyzed data by the past lessons and probabilistic statistics. Additionally will be installed MG(Mobile Generator) according to the lessons of Fukushima nuclear accident in Japan, which CDF(Core Damage Frequency) and LOOP frequency have reconsidered. And this paper proposed to reduce reliability criteria using PSA(Probabilistic Safety Analysis).

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.12-20
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• 2010

In a primary system at nuclear power plants (NPPs), various radionuclides including fission products and corrosion products are generated due to the complex water conditions. Particularly, $^3H,\;^{14}C,\;^{58}Co,\;^{60}Co,\;^{137}Cs,\;and^{131}I$ are important radionuclides in respect of dose assessment for radiation workers and management of radioactive effluents. In this paper, the dominant contributors of radiation exposure for radiation workers and the member of public adjacent to NPPs were reviewed and the process of dose assessment attributable to those contributors were introduced. Furthermore, the analysis for some examples of radiation exposure to radiation workers and the public during the NPP operation was carried out. This analysis included the notable precedents of internal radiation exposure and contamination of demineralized water occurred in Korean NPPs. Particularly, the potential issue about the dose assessment of tritium and carbon-14 was also reviewed in this paper.

• Nuclear Engineering and Technology
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• v.46 no.2
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• pp.225-234
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• 2014

Wall-thinned defects caused by accelerated corrosion due to fluid flow in the inner pipe appear in many structures of the secondary systems in nuclear power plants (NPPs) and are a major factor in degrading the integrity of pipes. Wall-thinned defects need to be managed not only when the NPP is under maintenance but also when the NPP is in normal operation. To this end, a test technique was developed in this study to detect such wall-thinned defects based on the temperature difference on the surface of a hot pipe using infrared (IR) thermography and a cooling device. Finite element analysis (FEA) was conducted to examine the tendency and experimental conditions for the cooling experiment. Based on the FEA results, the equipment was configured before the cooling experiment was conducted. The IR camera was then used to detect defects in the inner pipe of the pipe specimen that had artificially induced defects. The IR thermography developed in this study is expected to help resolve the issues related to the limitations of non-destructive inspection techniques that are currently conducted for NPP secondary systems and is expected to be very useful on the NPPs site.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2561-2567
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• 2018

The extension of DC battery backup time in the DC power supply system of nuclear power plants (NPPs) remains a challenge. The lead-acid battery is the most popular at present. And it is generally the most popular energy storage device. However, extension of backup time requires too much space. The lithium-ion battery has high energy density and advanced gravimetric and volumetric properties. The aim of this paper is development of the sizing formula of stationary lithium-ion batteries. The ongoing research activities and related industrial standards for stationary lithium-ion batteries are reviewed. Then, the lithium-ion battery sizing calculation formular is proposed for the establishment of industrial design standard which is essential for the design of stationary batteries of nuclear power plants. An example of calculating the lithium-ion battery capacity for a medium voltage UPS is presented.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.10 no.1
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• pp.31-36
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• 2014

For decreasing an unexpected shutdown of Nuclear Power Plants, Korea Hydro & Nuclear Power co.(KHNP) has developed Single Point Vulnerability(SPV) of NPPs since 2008. SPV is the equipment that cause reactor shutdown & turbine trip or more than 50% power rundown due to its malfunction. New type Nuclear Power Plants need to develop the SPV list, so performed the SPV selection for about 1 year. To develop this, Failure Mode Effect Analysis(FMEA) methods are used. As results of FMEA analysis, about 700 equipment are selected as SPV. Thereafter those are going to be applied to new type Nuclear Power Plants to enhance equipment reliability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.4
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• pp.509-512
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• 2012

For decreasing an unexpected shutdown of Nuclear Power Plants, Korea Hydro & Nuclear Power co.(KHNP) has developed Single Point Vulnerability(SPV) of NPPs since 2008. SPV is the equipment that cause reactor shutdown & turbine trip or more than 50% power rundown due to its malfunction. Newly built Nuclear Power Plants need to develop the SPV list, so performed the job which analyse equipment failure effect for SPV selection for 1 year. To develop this, Failure Mode Effect Analysis(FMEA) and Fault Tree Analysis(FTA) methods are used. As results of this analysis, about 900 equipment are selected as SPV. Thereafter those are going to be applied to Nuclear Power Plants to enhance equipment reliability.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.207-213
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• 2003

Carbon-14 is one of the major radionuclides released by CANDU Nuclear Power Plants(NPPs). It is almost always emitted as gas through the stack. From CANDU NPPs about 95% of all carbon-14 is released as carbon dioxide. Carbon-14 is a low energy beta emitter which, therefore, gives only a small skin dose from external radiation. As carbon dioxide Is physiologically rather inert gases for man's metabolism, the inhalation dose is probably less than 1 % of the ingestion dose. But this source of carbon-14, formed in a closed, nor-oxidative environment, was subsequently released into the workplace as an insoluble particulate when these systems were opened lip for re-tubing at CANDU NPPs. As a part of the improvement of dosimetry program at Wolsong Nuclear Power Plants, the carbon-14 metabolism based on references was investigated and studied to setup the internal dosimetry program due to inhalation of carbon-14.