• Journal of Radiation Protection and Research
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• v.39 no.2
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• pp.89-95
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• 2014

In potential accident consequence assessments for the licensing approval of LWRs, the ground deposition of radionuclides released into the environment is not allowed into the models, as recommended in the U. S. Nuclear Regulatory Commission's regulatory guide. Meanwhile, it is allowed into the assessment models for the licensing approval of PHWRs with consideration of more detailed physical processes of radionuclides in the atmosphere. Under these backgrounds, importance of exposure dose by ground deposition was quantitatively evaluated and comprehensively discussed. For potential accidental releases of $^{137}Cs$ and $^{131}I$, total exposure doses were more conservative in case of without consideration of ground deposition than in case of with its consideration. It was because of that the depletion of air concentration resulting from ground deposition is more influential in the contribution to total exposure doses than additional doses from contaminated ground. The exposure doses by the inhalation of contaminated air showed the contribution of more than 90% in total exposure doses, depending on atmospheric stability, release period of radionuclides and distance from a release point. The exposure doses from contaminated ground showed less than 10% at most in contribution of total exposure doses. The ratios of total exposure doses in case of with consideration of deposition to without its consideration for $^{131}I$ were distinct than those for $^{137}Cs$. As the atmosphere is more stable, release duration of radionuclides is longer, distance from a release point is longer, it was more distinct.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.99-108
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• 2020

Objectives: This study aimed to compare the regulatory systems for laboratory safety and health management between Korea and Germany and discuss the implications. Methods: Laboratory safety and health regulations for legal enforcement and relevant technical guidelines in Korea and Germany were reviewed. Results: Lab safety and health management is enforced by the Act on the Establishment of Safe Laboratory Environment in Korea. Most provisions focus on supervisory control, that is, the principal's liability is emphasized. In addition, there is a lack of laboratory-specific procedures for safety and health management in the act since it is stipulated that other relevant regulations apply to some technical contents. Non-compulsory technical guidelines for lab safety and health management are also provided by the Korea Occupational Safety and Health Agency (KOSHA) in order to enable researchers to follow safe procedures. There is no independent regulation for lab safety and health in Germany, and it is also governed by several regulations. The German Social Accident Insurance Institute provides technical guidelines on lab safety and health, and these contain more specific content to allow them to be followed more easily compared to the KOSHA guidelines. The most remarkable differences between the regulation of each country were contents of the risk assessment and specific protect measures from hazardous agents. Conclusions: Regulatory control is an essential way to prevent accidents, but it is more important to create an environment in which all stakeholders, including individual lab members, are allowed to participate actively in safety and health management activities.

• Geophysics and Geophysical Exploration
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• v.14 no.4
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• pp.274-281
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• 2011

We analysed ground motions form Mw 4.3 earthquake around Backryoung Island for the seismic source focal mechanism and horizontal response spectrum. Focal mechanism of the Backryoung Islands area was compared to existing principal stress orientation of the Korean Peninsula and horizontal response spectrum was also compared to those of the US NRC Regulatory Guide (1.60) and the Korean National Building Code. The ground motions of 3 stations, including vertical, radial, and tangential components for each station, were used for grid search method of moment tensor seismic source. The principal stress orientation from this study, ENE-WSW, is consistent fairly well with that of the Korean Peninsula. The horizontal response spectrum using 30 observed ground motions analysed and then were compared to both the seismic design response spectra (Reg Guide 1.60), applied to the domestic nuclear power plants, and the Korean Standard Design Response Spectrum for general structures and buildings (1997). Response spectrum of 30 horizontal ground motions were used for normalization with respect to the peak acceleration value of each ground motion. The results showed that the horizontal response spectrum revealed higher values for frequency bands above 3 Hz than Reg. Guide (1.60). The results were also compared to the Korean Standard Response Spectrum for the 3 different soil types and showed that the vertical response spectra revealed higher values for the frequency bands below 0.8 second than the Korean Standard Response Spectrum (SD soil condition). However, through the qualitative improvements and quantitative enhancement of the observed ground motions, the conservation of horizontal seismic design response spectrum should be considered more significantly for the higher frequency bands.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.04a
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• pp.19-25
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• 1992

The modal combination methods are studied for estimating the maximum structural responses in the seismic analysis by the response spectrum method. The most important problem in the modal combination is how to account for the correlation between the modal responses and to combine the high frequency modes (of which frequencies are greater than that at which the spectral acceleration approximately returns to the ZPA(zero period acceleration)). In this study, therefore, the widely known methods are investigated and compared among the numerous ones proposed up to now including those recommended in Regulatory Guide 1.92. The applicability of each method is investigated through example analyses also.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.16-21
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• 2001

The PTS reference temperature of reactor pressure vessel for one of the Korean NPPs has been predicted to exceed the screening criteria before it reaches it's design life. To cope with this issue, a plant-specific PTS analysis had been performed in accordance with the Regulatory Guide 1.154 in 1999. As a result of that analysis, it was found that current methodology of RG. 1.154 was very conservative. The objective of this study is to examine the effects of changing various input parameters and to determine the amount of conservatism of the current PTS analysis method. To do this, based on the past PTS analysis experience, parametric study were performed for various models using modified VISA-II code. This paper discusses the analysis results and recommendations to reduce the conservatism of current analysis method.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1274-1284
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• 1999

The Regulatory Guide 1.82 recommends an analysis of hydraulic performance for sump of ECCS (Emergency Core Cooing System) when LOCA(Loss of Coolant Accident) occurs in a nuclear power plant. The present study deals with 3-dimensional, unsteady, turbulent and two-phase flow simulation to examine the behavior of mixture of reactor coolant and debris near the floor of containment building in conjunction with appropriate assumptions. The dispersed solid model has been adjusted to the interfacial momentum transfer between reactor coolant and debris. According to the results, the counterclockwiserecirculation zone had been formed in the region between sump and connection aisle about 376 second after LOCA occurs. The debris thickness accumulated on a sump screen periodically increases or decreases up to 2000 second, afterwards its peak decreases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1210-1215
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• 2002

The spent fuel handling tool is used to handle the refuel bundle and treated by hoist rope on the bridge crane. The new developed handling tool of NPP(Nuclear Power Plant) should be conformed the structural stability under earthquake condition. In this study, the stress and seismic analysis of the handling tool are performed by finite element method. Using the Floor Response Spectrum(FRS) obtained through the time history analysis, the modal and seismic analysis under Operating Basis Earthquake(OBE) and Safe Shutdown Earthquake(SSE) load conditions are carried out. Total 4 cases of different locations of the trolly and the hook are investigated. With the spring-damper element, the tension analysis of hoist rope is conducted. The stability of handling tool under earthquake load condition is conformed with regulatory guide.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.899-904
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• 1995

원자로 수명기간동안 압력용기의 중성자 조사량 계산은 사용된 핵단면적자료, 모델링시의 기하학적인 단순화 및 가정, 그리고 선원항 선정에 있어서의 가정 등에 의한 불확실성을 포함하고 있다. 이중 핵단면적자료는 이론 및 실험의 발전에 따라 계속 개선되고 있으며 Regulatory Guide(1)에서는 압력용기에서의 중성자 조사량 계산시 가장 최근의 핵자료를 적용할 것을 명시하고 있다. 특히 기존의 ENDF/B-IV나 ENDF/B-V에 포함된 철 핵단면적이 중성자 투과를 작게 평가하고 있음이 밝혀지면서[2] 새로운 핵단면적의 채택이 필요하게되었다. ENDF/B-Vl 핵자료는 개선된 철의 핵단면적을 포함하여 여러 가지 최근의 계산 및 실험치를 바탕으로 생산되었다. 따라서 ENDF/B-Vl를 근거로 하고 있는 BUGLE93[3]을 이용하여 원자로 내부구조물 및 압력용기에서의 고속중성자속 계산을 수행하였다. 그리고 기존의 핵자료를 근거로 예측한 울진 3,4호기 원자로의 수명기간 중 압력용기 중성자 조사량 계산의 타당성을 검토하였다.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.04a
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• pp.161-167
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• 2000

주제어실의 경보계통은 중요한 발전소 변수의 비정상 상태 발생과 운전원의 관심을 요하는 기기상태의 변화에 대해 가시적/가정적 신호로 운전원에게 경고하는 역할을 담당하는 역할을 한다. 본 논문에서는 전력연구원에서 수행중인 '원자력 교육원 시뮬레이터 성능개선' 과제의 일부로 원자력교육원 2호기의 기준발전소인 영광 1호기의 디지털 경보설비 (IAS : Intelligent Annunciator System)의 구조와 이를 시뮬레이터 주컴퓨터 (Host Computer)상의 다이나믹 모델과 연동시켜 구현하는 방법론 및 구현된 경보감시계통에 대해 다루고 있다. 원자력교육원 2호기 경비감시계통은 Trend 모드, 그룹모드, 윈도우 모드, 조치사항 모드 및 조치사항 등록 모드 등 총 5개의 모드로 구성되어 있으며, 발생된 경보의 시간별/그룹별 출력, 경보창 에뮬레이션과 임의의 창에 대한 조치사항 출력, 새로운 경보에 대한 등록 및 삭제 등의 기능 구현이 가능하다. 또한 시뮬레이터에 대한 규제기관의 인허가가 중요한 현안으로 대두될 전망임에 따라 ANSI/ANS-3.5, Regulatory Guide 1.149 등 규제요건에서 제시하는 성능기준 및 검사기준을 만족하도록 설계함으로 향후 규제기관에 대한 인허가 획득을 대비하였다.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.324-329
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• 2004

In this study, an application of crack morphology variables in the Leak-Before-Break(LBB) evaluation for nuclear piping systems is investigated, including influences on the leakage crack size and crack instability loads. The crack surface roughness and the number of flow turns as a function of the crack opening displacement are applied to LBB evaluations for KSNP pressurizer surge line, for which fatigue and stress corrosion cracking are considered as failure mechanisms. As a result, there would be a significant impact on safety margins to acceptance criteria for the surge line if crack morphology variables are applied additionally to the current regulatory guide without re-analyses for justification of safety factors being applied on the leakage crack size and piping loads for evaluations.