• Journal of Radiation Industry
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• v.17 no.2
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• pp.209-217
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• 2023

The biosphere has important function in the safety assessment of a radioactive waste disposal facility. A biosphere model in the safety assessment needs various input data that contain significantly inherent uncertainties. This paper reviews the effects of the input data on the radiological impact assessment from main radionuclides such as ¹⁴C and ⁹⁹Tc in the biosphere model. In addition, it is confirmed that the safety criteria is met, when the conservative input data for the intake rate, soil to plant concentration ratio, and distribution coefficients of the radionuclides are applied and probabilistic analysis are conducted in the biosphere model. Nevertheless, it is required to generate site-specific input data for the confidence building and reduce excessive conservatism in the biosphere model.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.887-897
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• 2023

Leading waste disposal countries, such as Sweden, Switzerland, and the United Kingdom, conduct safety assessments across all stages of High-Level Radioactive Waste Deep Geological Disposal Facilities-from planning and site selection to construction, operation, closure, and post-closure management. As safety assessments are repeatedly performed at each stage, generating vast amounts of diverse data over extended periods, it is essential to construct a database for safety assessment and establish a data management system. In this study, the safety assessment data management systems of leading countries, were analyzed, categorizing them into 1) input and reference data for safety assessments, 2) guidelines for data management, 3) organizational structures for data management, and 4) computer systems for data management. While each country exhibited differences in specific aspects, commonalities included the classification of safety assessment input data based on disposal system components, the establishment of organizations to supply, use, and manage this data, and the implementation of quality management systems guided by instructions and manuals. These cases highlight the importance of data management systems and document management systems for securing the safety and enhancing the reliability of High-Level Radioactive Waste Disposal Facilities. To achieve this, the classification of input data that can be flexibly and effectively utilized, ensuring the consistency and traceability of input data, and establishing a quality management system for input data and document management are necessary.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.386-390
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• 2007

At recent times, an essential issue in the replacement of the old analogue I&C to computer-based digital systems in nuclear power plants becomes the quantitative software reliability assessment. Software reliability models have been successfully applied to many industrial applications, but have the unfortunate drawback of requiring data from which one can formulate a model. Software that is developed for safety critical applications is frequently unable to produce such data for at least two reasons. First, the software is frequently one-of-a-kind, and second, it rarely fails. Safety critical software is normally expected to pass every unit test producing precious little failure data. The basic premise of the rare events approach is that well-tested software does not fail under normal routine and input signals, which means that failures must be triggered by unusual input data and computer states. The failure data found under the reasonable testing cases and testing time for these conditions should be considered for the quantitative reliability assessment. We presented the quantitative reliability assessment methodology of safety critical software for rare failure cases in this paper.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.12 no.4
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• pp.345-361
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• 2014

The systematic quality assurance activities on documents of the safety assessment are required for the safety case of the low- and intermediate-level radioactive waste disposal facility. In this paper, quality assurance system focused on the input data including the site characterization, groundwater flow, system design and monitoring are prepared and discussed. Rule for the input data selection is suggested and applied for the safety assessment which is based on the in-situ/experiment observations, final facility design and waste pileup plan, engineered barrier, field monitoring, recent biosphere, and radionuclide inventory. The reduction of data uncertainty will be expected to contribute to the safety of disposal facility further.

• Nuclear Engineering and Technology
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• v.35 no.6
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• pp.556-565
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• 2003

A quality assurance safety assessment database, called QUARK (QUality Assurance Program for Radioactive Waste Management in Korea), has been developed to manage both analysis information and parameter database for safety assessment of low- and intermediate-level radioactive waste (LILW) disposal facility in Korea. QUARK is such a tool that serves QA purposes for managing safety assessment information properly and securely. In QUARK, the information is organized and linked to maximize the integrity of information and traceability. QUARK provides guidance to conduct safety assessment analysis, from scenario generation to result analysis, and provides a window to inspect and trace previous safety assessment analysis and parameter values. QUARK also provides default database for safety assessment staff who construct input data files using SAGE(Safety Assessment Groundwater Evaluation), a safety assessment computer code.

• Journal of the Korean Society of Safety
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• v.36 no.2
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• pp.111-119
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• 2021

Multi-dimensional analysis of reactor safety-KINS standard (MARS-KS) is a thermal-hydraulic code to simulate multiple design basis accidents in reactors. The code has been essential to assess nuclear safety, but has mainly focused on light water reactors, which are in the majority in South Korea. Few previous studies considered pressurized heavy water reactor (PHWR) applications. To verify the code applicability for PHWRs, it is necessary to develop MARS-KS input decks under various transient conditions. This study proposes an input model to simulate small-break loss of coolant accidents for PHWRs. The input model includes major equipment and experimental conditions for test B9802. Calculation results for selected variables during steady-state closely follow test data within ±4%. We adopted the Henry-Fauske model to simulate break flow, with coefficients having similar trends to integrated break mass and trip time for the power supply. Transient calculation results for major thermal-hydraulic factors showed good agreement with experimental data, but further study is required to analyze heat transfer and void condensation inside steam generator u-tubes.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.96-101
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• 2011

In previous studies, a system was developed for classifying items of uninsured cost and for generating factors and formulas by item for calculating accident loss costs. However, the loss cost of stopped production was not considered when the system was being developed. In addition, the system which was developed in previous studies had problems such as input error and data collection, owing to numerous input items. Therefore, this study developed a Revised system which considers the loss cost of stopped production, and a Simple system for improving the problems in input errors and data collection. In this study, unquantifiable factors were not considered. Further study that takes these factors into consideration is necessary.

• Nuclear Engineering and Technology
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• v.38 no.6
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• pp.575-584
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• 2006

As the development of total management systems for sites along with site environmental information is becoming standard, the system known as the Site Information and Total Environmental database management System (SITES) has been developed over the last two years. The first result was a database management system for storing data obtained from facilities, and a site characterization in addition to an environmental assessment of a site. The SITES database is designed to be effective and practical for use with facility management and safety assessment in relation to Geographic Information Systems. SITES is a total management program, which includes its database, its data analysis system required for site characterization, a safety assessment modeling system and an environment monitoring system. It can contribute to the institutional management of the facility and to its safety reassessment. SITES is composed of two main modules: the SITES Database module (SDM) and the Monitoring & Assessment (M&A) module [1]. The M&A module is subdivided into two sub-modules: the Safety Assessment System (SAS) and the Site Environmental Monitoring System (SEMS). SAS controls the data (input and output) from the SITES DB for the site safety assessment, whereas SEMS controls the data obtained from the records of the measuring sensors and facilities. The on-line site and environmental monitoring data is managed in SEMS. The present paper introduces the procedure and function of the M&A modules.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.3
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• pp.191-199
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• 2012

Objectives: The study aim was to evaluate the application of a chemical exposure assessment tool for the Korean workplace. The Ministry of Employment and Labor in Korea (KMOEL) introduced the need for workplace risk assessments in 2011, requiring the Korean chemical industry to consider both domestic and international chemical regulation policies (e.g., estimations of exposure scenarios). Exposure scenarios are required in the European Union as part of material safety data sheets (MSDS) under the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) system. Methods: Although many programs for the estimation of exposure have been developed worldwide, to date there is no standard for the Korean workplace. To develop programs suitable for the Korean workplace, we examined the applicability of the European Center for Ecotoxicology and Toxicology of Chemicals target risk assessment (ECETOC TRA), which is recommended by the European Chemical Agency (ECHA). Results: To investigate the applicability of the ECETOC TRA to Korean industry, this study simulated 15 industrial processes. The predicted respiratory exposures for four processes using origin input parameters were underestimated compared to the measured respiratory exposure. Using calibrated input parameters, results for two processes were underestimated compared to the measured respiratory exposure. This result suggests that the use of calibrated input parameters reduces the differences between predicted and measured respiratory exposure. Conclusions: we developed applicable exposure estimating method by modifying the ECETOC TRA program; one suggested the development of exposure estimating program that explains Korea domestic workplace exposure scenario.This study will support the introduction of exposure scenario in MSDS system and protect health of worker from hazardous chemical.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.113-121
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• 2021

A safety assessment of radioactive waste repositories is a mandatory requirement process because there are possible radiological hazards owing to radionuclide migration from radioactive waste to the biosphere. For a reliable safety assessment, it is important to establish a parameter database that reflects the site-specific characteristics of the disposal facility and repository site. From this perspective, solubility, a major geochemical parameter, has been chosen as an important parameter for modeling the migration behavior of radionuclides. The solubilities were derived for Am, Ni, Tc, and U, which were major radionuclides in this study, and on-site groundwater data reflecting the operational conditions of the Gyeongju low and intermediate level radioactive waste (LILW) repository were applied to reflect the site-specific characteristics. The radiation dose was derived by applying the solubility and radionuclide inventory data to the RESRAD-OFFSITE code, and sensitivity analysis of the dose according to the solubility variation was performed. As a result, owing to the low amount of radionuclide inventory, the dose variation was insignificant. The derived solubility can be used as the main input data for the safety assessment of the Gyeongju LILW repository in the future.