• Nuclear Engineering and Technology
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• 제46권1호
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• pp.47-54
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• 2014

The protection of nuclear safety software is essential in that a failure can result in significant economic loss and physical damage to the public. However, software security has often been ignored in nuclear safety software development. To enforce security considerations, nuclear regulator commission recently issued and revised the security regulations for nuclear computer-based systems. It is a great challenge for nuclear developers to comply with the security requirements. However, there is still no clear software development process regarding security activities. This paper proposes an integrated development process suitable for the secure development requirements and system security requirements described by various regulatory bodies. It provides a three-stage framework with eight security activities as the software development process. Detailed descriptions are useful for software developers and licensees to understand the regulatory requirements and to establish a detailed activity plan for software design and engineering.

• 한국안전학회지
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• 제37권5호
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• pp.74-79
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• 2022

This study analyzes the contents of the second revised Regulatory Guide 1.180 (Revision 2) for electromagnetic compatibility qualification published by the U. S. Nuclear Regulatory Commission by comparing them with those of the previous version. The methods and acceptance criteria of both CE101 and CE102 tests pertaining to conductive emission and RE102 test for radiation emission are observed to have been modified in Revision 2. Furthermore, the revised guide is found to afford flexibility in using alternative methods for electromagnetic interference qualification by allowing the combination of different technical base standards.

• Nuclear Engineering and Technology
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• 제45권3호
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• pp.277-294
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• 2013

In the early 1980s, attention focused on the possibility that pressurized thermal shock (PTS) events could challenge the integrity of a nuclear reactor pressure vessel (RPV) because operational experience suggested that overcooling events, while not common, did occur, and because the results of in-reactor materials surveillance programs showed that RPV steels and welds, particularly those having high copper content, experience a loss of toughness with time due to neutron irradiation embrittlement. These recognitions motivated analysis of PTS and the development of toughness limits for safe operation. It is now widely recognized that state of knowledge and data limitations from this time necessitated conservative treatment of several key parameters and models used in the probabilistic calculations that provided the technical of the PTS Rule, 10 CFR 50.61. To remove the unnecessary burden imposed by these conservatisms, and to improve the NRC's efficiency in processing exemption and license exemption requests, the NRC undertook the PTS re-evaluation project. This paper provides a synopsis of the results of that project, and the resulting Alternate PTS rule, 10 CFR 50.61a.

• 방사성폐기물학회지
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• 제19권1호
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• pp.141-160
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• 2021

Unit 1 of the Kori Nuclear Power Plant (NPP) and Unit 1 of the Wolsong NPP are being prepared for decommissioning; their decommissioning is expected to generate large amounts of intermediate-level, low-level, and very low level Waste. Mixed waste containing both radioactive and hazardous substances is expected to be produced. Nevertheless, laws and regulations, such as the Korean Nuclear Safety Act and Waste Management Act, do not define clear regulatory guidelines for mixed waste. However, the United States has strictly enforced regulations on mixed waste, focusing on the human health and environmental effects of its hazardous components. The U.S. Nuclear Regulatory Commission and the U.S. Department of Energy regulate the radioactive components of mixed waste under the Atomic Energy Act. The U.S. Environmental Protection Agency regulates the hazardous waste component of mixed waste under the Resource Conservation and Recovery Act. In this study, the laws, regulations, and authorities pertaining to mixed waste in the United States are reviewed. Through comparison and analysis with waste management laws and regulations in Korea, a treatment direction for mixed waste is suggested. Such a treatment for mixed waste will increase the efficiency of managing mixed waste when decommissioning NPPs in the near future.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.309-316
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• 2024

The U.S. Nuclear Regulatory Commission (NRC) Regulatory Guide (RG) 1.20 provides guidance on the comprehensive vibration assessment program (CVAP) to be performed on reactor internals during preoperational and startup tests. The purpose of the program is to identify loads that could cause vibration in the reactor internals and to ensure that these vibrations do not affect their structural integrity. The structural vibrational analysis program involves creating finite element analysis models of the reactor internals and calculating their structural responses when subjected to vibration loads. The appropriateness of the structural analysis methodology must be demonstrated through benchmarks or any other reasonable means. Although existing structural analysis methodologies have been proven to be appropriate and are widely used, this paper presents the development of an improved new structural analysis methodology for APR1400 reactor internals using scaled model tests.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 추계학술대회 논문집
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• pp.433-438
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• 2010

Reactor vessel internals comprehensive vibration assessment program(RVI CVAP) is one of the necessary tests to ensure the safety of nuclear power plants. RVI CVAP of U.S. Nuclear Regulatory Commission Regulatory Guide 1.20(U.S. NRC R.G. 1.20) consists of the analysis, measurement, and inspection. One of the core technologies of the measurement program for RVI CVAP is to select suitable sensors. We analyzed RVI design data of Palo Verde nuclear generating station(U.S.) and Yonggwang nuclear generating station(Korea) and investigated measuring sensors used in both of them; moreover, we investigated sensors used for measurement of RVI CVAP for the last 20 years throughout the world. Based on these results, we selected the most suitable sensors for RVI CVAP in Advanced Power Reactor 1400(APR1400).

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.963-970
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• 2018

The U.S. Nuclear Regulatory Commission, Regulatory Guide 1.20 needs to perform a comprehensive vibration assessment program for reactor internals during preoperational and startup testing for nuclear power plants and extended power uprate. Although the measurement program is one of the core programs, it is rarely carried out except for a first-of-a-kind or a unique design. This article describes measurement results of vibration and stress for the comprehensive vibration assessment program for an APR-1400 reactor internals. The measurement was performed at an upper guide structure during the pre-core hot functional test of Shin Kori unit 4 reactor internals because the Shin Kori unit 3 and 4 are the first construction project for the APR-1400, and the upper guide structure assembly was to design change compared with the valid prototype. We confirmed that all measured results are within the test acceptance criteria. It means that the structural integrity of the APR-1400 reactor internals was secured for the flow-induced vibration.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.1109-1112
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• 2017

The precise prediction of radiation embrittlement of aged reactor pressure vessels (RPVs) is a prerequisite for the long-term operation of nuclear power plants beyond their original design life. The expiration of the operation licenses for Korean reactors the RPVs of which are made from SA533B-1 plates and welds is imminent. Korean regulatory rules have adopted the US Nuclear Regulatory Commission's transition temperature shift (TTS) models to the prediction of the embrittlement of Korean reactor pressure vessels. The applicability of the TTS model to predict the embrittlement of Korean RPVs made of SA533B-1 plates and welds was investigated in this study. It was concluded that the TTS model of 10 CFR 50.61a matched the trends of the radiation embrittlement in the SA533B-1 plates and welds better than did that of Regulatory Guide (RG) 1.99 Rev. 2. This is attributed to the fact that the prediction performance of 10 CFR 50.61a was enhanced by considering the difference in radiation embrittlement sensitivity among the different types of RPV materials.

• Journal of Radiation Protection and Research
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• 제33권4호
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• pp.183-196
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• 2008

원전주변의 주민에 대한방사선량의 대부분을 음식물 섭취에 의한 내부피폭이 차지하고 있다. 그러나 우리나라 원전에 적용하고 있는 음식물 섭취 관련 인자는 1989년 한국원자력연구소가 고리원전 주변지역을 대상으로 수행한 현장조사 결과를 계속 적용하고 있어 최근의 식습관 변화를 적절히 반영하지 못하고 있다. 또한 우리나라는 미국 NRC (Nuclear Regulatory Commission) 에서 적용하고 있는 최대개인에 근거하여 음식물 섭취율을 결정하고 있다. 그러나 최근의 ICRP (International Commission on Radiological Protection) 의 권고 및 유럽의 관련 지침에서는 결정집단 또는 결정집단을 대표하는 개인에 대해 선량을 평가토록 권고하고 있다. 따라서 이러한 식습관의 변화추이나 피폭평가대상에 대한 국제적인 권고기준에 준하는 음식물 섭취율 설정방법에 대한연구가 필요하다. 보건복지가족부에서는 국민건강증진법에 의거 매 3년마다 전국 규모의 국민의 식품 및 영양섭취실태 조사를 실시하고 있다. 따라서 본 연구에서는 이러한 정부조사자료를 활용하여 주기적으로 음식물 섭취량 자료를 갱신할 수 있는 방안을 연구하였다. 보건복지가족부에서 $2001{\sim}2002$년에 수행한 국민영양조사원자료(raw data)를 분석하여 결정집단을 대표하는 개인의 음식물 섭취율을 결정하는데 이용할 수 있는 기초통계량을 제시하고, 또한 현재 국내 원전에서 적용하고 있는 최대개인의 음식물 섭취율을 재설정하였다.

• Nuclear Engineering and Technology
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• 제44권7호
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• pp.817-824
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• 2012

The most important component of a nuclear power plant is its nuclear reactor. Studies on the integrity of reactors have become an important part regarding the safety of a nuclear power plant. The US Nuclear Regulatory Commission Regulatory Guide (NRC RG) 1.20 presents a Comprehensive Vibration Assessment Program (CVAP) to be used to verify the structural integrity of the Reactor Vessel Internals (RVI) for flow-induced vibration prior to commercial operation. However, there are few published studies related to the RVI CVAP. We classified the Advanced Power Reactor 1400 (APR1400) RVI CVAP as a non-prototype category-2 reactor as part of an independent validation of its design. The aim of this paper is to present the results of structural response analyses of the Upper Guide Structure (UGS) assembly of the APR1400 reactor. These results show that the UGS and the Inner Barrel Assembly (IBA) meet the specified integrity levels of the design acceptance criteria. The vibration and stress analysis results in this paper will be used as basic information to select measurement locations of the vibration and stress for the APR1400 RVI CVAP.