• Nuclear Engineering and Technology
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• 제37권2호
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• pp.191-200
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• 2005

Shaking table tests of the seismic behavior of a steel frame structure model were performed. The purpose of these tests was to estimate the effects of a near-fault ground motion and a scenario earthquake based on a probabilistic seismic hazard analysis for nuclear power plant structures. Three representative kinds of earthquake ground motions were used for the input motions: the design earthquake ground motion for the Korean nuclear power plants, the scenario earthquakes for Korean nuclear power plant sites, and the near-fault earthquake record from the Chi-Chi earthquake. The probability-based scenario earthquakes were developed for the Korean nuclear power plant sites using the PSHA data. A 4-story steel frame structure was fabricated to perform the tests. Test results showed that the high frequency ground motions of the scenario earthquake did not damage the structure at the nuclear power plant site; however, the ground motions had a serious effect on the equipment installed on the high floors of the building. This shows that the design earthquake is not conservative enough to demonstrate the actual danger to safety related nuclear power plant equipment.

• 한국지진공학회논문집
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• 제16권3호
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• pp.35-42
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• 2012

암반지반에 주어진 등재해도 스펙트럼에 상응하는 원전부지 토사지반에서의 등재해도 스펙트럼을 도출하기 위한 확률론적 방법론을 제시하였다. 이를 위해 지진 운동 및 지반의 불확실성을 고려한 지반응답 해석을 통해 토사지반 지표에서의 지진동 증폭계수를 산정하였다. 증폭계수는 가장 상관관계가 높은 지반운동의 스펙트럴 가속도 규모와의 회귀분석을 통해 계산되었다. 이 방법론을 적용하여 국내 KNGR (Korean Next Generation Reactor) 및 APR1400 (Advanced Power Reactor 1400) 원전의 포괄부지 지반 중 B1, B4, C1 및 C3 지반을 대상으로 등재해도 스펙트럼을 도출하였다. 등재해도 스펙트럼을 통해 지진동 발생 빈도 별 위험 주파수 대역을 평가하고 분석하였다. 이 결과는 원전의 종합적 지진리스크 평가 결과를 보다 합리적으로 개선하는 데에 활용될 수 있으며, 향후 다양한 종류의 토사지반에 대한 등재해도 스펙트럼을 평가하는 데에 적용할 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제41권10호
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• pp.1255-1262
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• 2009

This paper introduces the status of and issues related to the PSHA (Probabilistic Seismic Hazard Analysis) of Korean Nuclear Power Plant sites. PSHA was first introduced to the nuclear industry in the mid-1980s. The Korean PSHA is based on Cornell and accommodates the modem approach for eliciting expertise and statistical treatment. Due to the low seismicity in Korea, large uncertainties exist in the PSHA database including seismic source maps, seismicity parameters of seismic sources, and attenuation formulae. Though research in seismology, geology, and earthquake engineering since the mid-1990s has significantly reduced uncertainties, a considerable amount still exists. Considering the low seismicity of the Korean Peninsula, especially the lack of strong motion data, further reduction will take several decades.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.366-372
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• 2020

Using several accessible published data sets, we analyzed the temporal change of ¹³⁷Cs radioactivity (per unit mass of sample) in marine sediments and investigated the effect of the water content of sediment on the ¹³⁷Cs radioactivity, to understand the behavior of ¹³⁷Cs present in marine environments. The ¹³⁷Cs radioactivity in sediments decreased more slowly in the Baltic Sea (near the Chernobyl nuclear power plant) than in the ocean near the Fukushima Daiichi nuclear power plant (FDNPP). The ¹³⁷Cs radioactivity in the sediment near the FDNPP tended to increase as the water content increased, and the water content decreased at certain sampling sites near the FDNPP for several years. Additionally, the decrease in the water content contributed to 51.2% of the average ¹³⁷Cs radioactivity decrease rate for the same period. Thus, it may be necessary to monitor both the ¹³⁷Cs radioactivity and the water content for marine sediments to track the ¹³⁷Cs that was discharged from the sites of Chernobyl and Fukushima nuclear power plants where severe accidents occurred.

• 자원환경지질
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• 제51권2호
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• pp.203-211
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• 2018

국내 원전부지 지진재해도 평가 경험을 바탕으로 향후 지진재해도 평가 시 보다 정량적인 평가를 위하여 고려하여야 할 사항에 대하여 점검하였다. 지진재해도 평가 방법을 양분하는 것으로 알려진 결정론적 방법과 확률론적 방법에 대하여 간단히 소개하였으며, 대부분의 후속 논의는 확률론적 지진재해도 평가에 집중하였다. 이 평가를 국내 원전부지에 적용한 과거 사례를 토대로 제기된 불확실성의 원인을 추적하였다. 확률론적 지진재해도 평가의 고려사항으로 전문가의 역할, 대표지진목록 작성, 지진원 설정, 지진-지반운동 관계식 개발 및 지진재해도 평가 절차에 대하여 토의하였다. 각 주제별로 불확실성을 증가시키는 요인을 분석하고 국내 환경에 적합한 해결 방안을 토의하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.525-528
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• 1993

KEPCO Research Center is carrying out a simulator(full scope replica type) development project for two nuclear power plants(Kori-2, Younggwang-3,4) and one fossil power plant(Poryong-3,4). In this project, we aim not only the installation of high performance simulators at the power plant sites but also the realization of self reliance of power plant simulation technology in Korea. In the course of preparing procurement specification for the 3 simulators, the present status of power plant simulation technology has been surveyed and is presented in this paper. The fidelity of simulation and the automation of simulation model production has been greatly improved due to the ever increasing computing power of today's workstations. The need and importance of the application of high fidelity simulators to the operator training is refocused since the accident at TMI Nuclear Power Plant, U.S.A.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1217-1233
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• 2018

Following a surge of interest in multi-unit risk in the last few years, many recent studies have suggested methods for multi-unit probabilistic safety assessment (MUPSA) and addressed several related aspects. Most of the existing studies though focused on two-unit nuclear power plant (NPP) sites or used rather simplified probabilistic safety assessment (PSA) models to demonstrate the proposed approaches. When considering an NPP site with three or more units, some approaches are inapplicable or yield very conservative results. Since the number of such sites is increasing, there is a strong need to develop and validate practical approaches to the related MUPSA. This article provides several detailed approaches that are applicable to multi-unit Level 1 PSA for sites with up to six or more reactor units. To validate the approaches, a multi-unit Level 1 PSA model is developed and the site core damage frequency is estimated for each of four representative multi-unit initiators, as well as for the case of a simultaneous occurrence of independent single-unit initiators in multiple units. For this purpose, an NPP site with six identical OPR-1000 units is considered, with full-scale Level 1 PSA models for a specific OPR-1000 plant used as the base single-unit models.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1998년도 춘계 학술발표회 논문집
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• pp.271-277
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• 1998

1. Why Wind Power\ulcorner Advantages of Wind Energy : free cost, non-pollutant, free waste large unit is possible Disadvantages : intermittent of energy density limited sites Unit Capacity of various Power Plant Solar PP : 10 - 500㎾ Wind PP : 200 - 2000 ㎾ Nuclear PP 700 - 1000 MW Installation Cost of Power Plants Nuclear PP : $ 2,500/㎾ Solar PP : $ 6,000/㎾ Wind PP : $ 1.000 /kw.

• Journal of Korean Society for Atmospheric Environment
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• 제10권E호
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• pp.299-302
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• 1994

At a nuclear power plant, environmental radioactivity monitoring is routine work for the radiation safety management For the environmental monitoring of tritium($^3$H) activity in water sampled liquid scintillation counting( LSC) method is applied to measure low- energy beta activity from tritium in the samples. The $^3$H activity is measured using the BECKMAN 5801 system at the KRISS( Korea Research Institute of Standards and Science) for evaluating the lower limits of detection( LLD) of $^3$H measurement and the measuring capability of low-level $^3$H activity at four nuclear Power Plant sites. The LSC systems used for low-level $^3$H activity measurements at the nuclear Power Plants are confirmed to satisfy throughout an intercomparison study under the experimental arrangements by the KRISS.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2529-2539
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• 2022

Stochastic and an empirical Green's function (EGF) methods are preliminarily applied to simulate strong ground motions (SGMs) at seismic stations within nuclear power plant (NPP) sites in South Korea by an assumed large earthquake with M_W6.5 (scenario earthquake) on the causative fault of the 2016 Gyeongju earthquake with M_W5.5 (mainshock). In the stochastic method, a ratio of spectral amplitudes of observed and simulated waveforms for the mainshock is assumed to be an adjustment factor. In the EGF method, SGMs by the mainshock are simulated assuming SGMs by the 2016 Gyeongju earthquake with M_W5.0 (foreshock) as the EGF. To simulate SGMs by the scenario earthquake, a ratio of fault length to width is assumed to be 2:1 in the stochastic method, and SGMs by the mainshock are assumed to be EGF in the EGF method. The results are similar based on a bias of the simulated response spectra by the two methods, and the simulated response spectra by the two methods exceeded commonly standard design response spectra anchored at 0.3 g of NPP sites slightly at a frequency band above 4 Hz, but considerable attention to interpretation is required since it is an indirect comparison.