• Nuclear Engineering and Technology
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• v.44 no.7
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• pp.745-754
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• 2012

The correlations between Large Early Release Frequency (LERF) and Early Fatality need to be investigated for risk-informed application and regulation. In Regulatory Guide (RG) -1.174, while there are decision-making criteria using the measures of Core Damage Frequency (CDF) and LERF, there are no specific criteria on LERF. Since there are both huge uncertainties and large costs needed in off-site consequence calculation, a LERF assessment methodology needs to be developed, and its correlation factor needs to be identified, for risk-informed decision-making. A new method for estimating off-site consequence has been presented and performed for assessing health effects caused by radioisotopes released from severe accidents of nuclear power plants in this study. The MACCS2 code is used for validating the source term quantitatively regarding health effects, depending on the release characteristics of radioisotopes during severe accidents. This study developed a method for identifying correlations between LERF and Early Fatality and validates the results of the model using the MACCS2 code. The results of this study may contribute to defining LERF and finding a measure for risk-informed regulations and risk-informed decision-making.

• Nuclear Engineering and Technology
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• v.52 no.1
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• pp.69-77
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• 2020

After the Fukushima Daiichi accidents, public concerns on nuclear safety and the corresponding burden of nuclear power plant licensees are increasing. In order to secure public trust and enhance the rationality of current safety regulation, we develop a risk-informed decision making (RIDM) framework for the Korean regulatory body. By analyzing all the regulatory activities for nuclear power plants in Korea, eight action items are selected for RIDM implementation, with appropriate procedures developed for each. For two items in particular - the accident sequence precursor analysis (ASPA) and the significance determination process (SDP) - two customized risk evaluation software has been developed for field inspectors and probabilistic safety assessment experts, respectively. The effectiveness of the proposed RIDM framework is demonstrated by applying the ASPA procedure to 35 unplanned scrams and the SDP to 24 findings from periodic inspections.

• Journal of the Korean Society of Safety
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• v.18 no.2
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• pp.86-91
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• 2003

The utility and the nuclear research institutes in korea have conducted research for improving inefficient requirements in technical specifications using the results of probability risk assessments and informations with risk. However, the guidance for reviewing the improved technical specifications has not been developed. The objective of this study is to develop a decision-making framework for investigating and reviewing the technical documents associated with the to changes of technical specification This study has developed a decision-making framework for reviewing the improvements of the RI-TS(Risk-Informed Technical Specifications). This work may contribute to enhancing both the safety and the efficiency of nuclear power plants by changing Technical Specifications proposed by the utility.

• Nuclear Engineering and Technology
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• v.40 no.5
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• pp.327-348
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• 2008

A risk-informed regulatory approach implies that risk insights be used as supplement of deterministic information for safety decision-making purposes. In this view, the use of risk assessment techniques is expected to lead to improved safety and a more rational allocation of the limited resources available. On the other hand, it is recognized that uncertainties affect both the deterministic safety analyses and the risk assessments. In order for the risk-informed decision making process to be effective, the adequate representation and treatment of such uncertainties is mandatory. In this paper, the risk-informed regulatory framework is considered under the focus of the uncertainty issue. Traditionally, probability theory has provided the language and mathematics for the representation and treatment of uncertainty. More recently, other mathematical structures have been introduced. In particular, the Dempster-Shafer theory of evidence is here illustrated as a generalized framework encompassing probability theory and possibility theory. The special case of probability theory is only addressed as term of comparison, given that it is a well known subject. On the other hand, the special case of possibility theory is amply illustrated. An example of the combination of probability and possibility for treating the uncertainty in the parameters of an event tree is illustrated.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1099-1105
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• 2018

How to choose defaults in risk-informed regulations depends on the conservatism implicated in regulatory defaults. Without a universal agreement on the approaches dealing with the conservatism of defaults, however, the desirability of conservatism in regulatory risk analyses has long been controversial. The opponent views it as needlessly costly and irrational, and the proponent as a form of protection against possible omissions or underestimation of risks. Moreover, the inherent ambiguity of risk makes it difficult to set suitable defaults in terms of risk. This paper, the extension of the previous work [1], focuses on the effects of different levels of conservatism implicated in regulatory defaults on the estimates of risk. According to the postulated behaviors of regulated parties and the diversity of interests of regulators, in particular, various measures for evaluating the effect of conservatism in defaults are developed and their properties are explored. In addition, a simple decision model for setting regulatory defaults is formulated, based on the understanding of the effect of conservatism implicated in them. It can help decision makers evaluate the levels of safety likely to result from their regulatory policies.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.213-213
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• 2001

• Fire Science and Engineering
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• v.17 no.1
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• pp.40-45
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• 2003

In this paper many vulnerable areas of the present fire PSA methodology were revealed to apply risk-informed fire protection to nuclear power plants. The results and insights from the fro PSA should be used as a part of a risk-informed decision making process rather than the complete technical basis for decision making. The degree of support and scope of applications is dependent on the accuracy and validity of the model used in the fire PSA. Accordingly; the usefulness of the fire PSA will increase as ongoing research and development efforts lead to improvements in the state of the art technology and as improvements in the implementation of the state of the art technology lead to more consistent results.

• Journal of Korean Academy of Nursing Administration
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• v.12 no.2
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• pp.255-264
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• 2006

Purpose: This study was carried out to understand the in-patients' experiences related on informed consent for examination, treatment or surgery. Method: The study was conducted with 578 patients who were admitted to the departments of internal medicine and surgery for examination, treatment or surgery requiring informed consent from November 1 to 30, 2004 at three general hospitals in Daegu, Busan and Gyeongsangbuk-do. The data was analyzed by using SPSS 11.5 for Windows. Results: Although the one who explains during the process of informed consent should be doctors, 6.6% was informed by nurses or others. In addition, the majority has been told for complications and risk while relatively fewer patients were informed for necessity, method and costs of the procedure, and no one ever heard of other alternatives or the right to terminate the procedure at any time. While 40% of patients were not the final decision-makers of examination, treatment or surgery, 11.9% of patients answered their opinions were not considered during the final decision-making process. Conclusion: The study suggest that the ethically appropriate informed consent has not been achieved in the clinical practice, and therefore it is necessary to develop the specific behavioral guidelines and nursing ethics education program for nurses in order to settle down the desirable informed consent at the dimension of nursing management.

• Nuclear Engineering and Technology
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• v.52 no.4
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• pp.764-775
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• 2020

Periodic safety reviews (PSRs) are conducted on operating nuclear power plants (NPPs) and have been mandated also for research reactors in Korea, in response to the Fukushima accident. One safety review tool, the probabilistic safety assessment (PSA), aims to identify weaknesses in the design and operation of the research reactor, and to evaluate and compare possible safety improvements. However, the PSA for research reactors is difficult due to scarce data availability. An important element in the analysis of research reactors is the reactor protection system (RPS), with its functionality and importance. In this view, we consider that of the AGN-201K, a zero-power reactor without forced decay heat removal systems, to demonstrate a risk-informed safety improvement study. By incorporating risk- and safety-significance importance measures, and sensitivity and uncertainty analyses, the proposed method identifies critical components in the RPS reliability model, systematically proposes potential safety improvements and ranks them to assist in the decision-making process.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2941-2959
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• 2022

The fire brigade non-suppression probability model is a major factor that should be considered in evaluating fire-induced risk through fire probabilistic risk assessment (PRA), and also uncertainty is a critical consideration in support of risk-informed performance-based (RIPB) fire protection decision-making. This study developed an optimal integrated probabilistic fire brigade non-suppression model considering uncertainty of parameters based on the Bayesian Markov Chain Monte Carlo (MCMC) approach on electrical fire which is one of the most risk significant contributors. The result shows that the log-normal probability model with a location parameter (µ) of 2.063 and a scale parameter (σ) of 1.879 is best fitting to the actual fire experience data. It gives optimal model adequacy performance with Bayesian information criterion (BIC) of -1601.766, residual sum of squares (RSS) of 2.51E-04, and mean squared error (MSE) of 2.08E-06. This optimal log-normal model shows the better performance of the model adequacy than the exponential probability model suggested in the current fire PRA methodology, with a decrease of 17.3% in BIC, 85.3% in RSS, and 85.3% in MSE. The outcomes of this study are expected to contribute to the improvement and securement of fire PRA realism in the support of decision-making for RIPB fire protection programs.