• Nuclear Engineering and Technology
• /
• v.47 no.1
• /
• pp.1-10
• /
• 2015

After the Fukushima Daiichi nuclear power plant (NPP) accident, new regulatory requirements were enforced in July 2013 and a backfit was required for all existing nuclear power plants. It is required to take measures to prevent severe accidents and mitigate their radiological consequences. The Regulatory Standard and Research Department, Secretariat of Nuclear Regulation Authority (S/NRA/R) has been conducting numerical studies and experimental studies on relevant severe accident phenomena and countermeasures. This article highlights fission product (FP) release and hydrogen risk as two major areas. Relevant activities in the S/NRA/R are briefly introduced, as follows: 1. For FP release: Identifying the source terms and leak mechanisms is a key issue from the viewpoint of understanding the progression of accident phenomena and planning effective countermeasures that take into account vulnerabilities of containment under severe accident conditions. To resolve these issues, the activities focus on wet well venting, pool scrubbing, iodine chemistry (in-vessel and ex-vessel), containment failure mode, and treatment of radioactive liquid effluent. 2. For hydrogen risk: because of three incidents of hydrogen explosion in reactor buildings, a comprehensive reinforcement of the hydrogen risk management has been a high priority topic. Therefore, the activities in evaluation methods focus on hydrogen generation, hydrogen distribution, and hydrogen combustion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.331-336
• /
• 2011

When the Fukushima nuclear power plant accident occurred in March, a hydrogen explosion in the reactor building at the 4th unit of Fukushima plants lead to a big surprise because the full core of the unit 4 reactor had been moved and stored underwater at the spent nuclear fuel storage pool for periodic maintenance. It was because the potential criticality in the fuel storage pool by coolant loss may yield more severe situation than the similar accident happened inside the reactor vessel. In the paper, the safety state of the spent fuel storage pool and rack structures of the domestic nuclear plants would be reviewed and compared with the Fukushima plant case by engineering viewpoint of potential severe accidents.

• Journal of Navigation and Port Research
• /
• v.47 no.3
• /
• pp.174-181
• /
• 2023

Five local governments along the Korea-Japan Sea (Jeju, Jeonnam, Gyeongnam, Busan, Ulsan) operate a joint countermeasure committee regarding the marine discharge of contaminated water from the Fukushima nuclear power plant by Japan's Tokyo Electric Power Plant. This study compared and analyzed citizen surveys, response strategies, and detailed action plans conducted by the Jeju Research Institute, Busan Research Institute, and Ulsan Research Institute as part of a study on countermeasures for the marine discharge of contaminated water from the Fukushima nuclear power plant in Japan. The purpose was to present basic data for the preparation of effective measures. As a result of the perception survey, all citizens of local governments showed a strong negative perception of marine discharge regardless of scientific research results, and it is expected that future fisheries and tourism industries will suffer great damage. In response strategies for each local government, building a control tower was found to be the most urgent task common to all local governments. It is judged that this is because it is necessary to break away from the organization-centered system and to respond to the function-centered system for effective response. In terms of response methods, while Jeju and Busan established response plans for each sector, Ulsan City focused on practical responses with step-by-step response measures according to the release time. In terms of content, the establishment of a marine product radiation inspection system and publicity to relieve public anxiety were important. As the marine discharge of contaminated water from the Fukushima nuclear power plant is scheduled to continue until 2030, strengthening the network for sharing research results and achievements among local government research institutes was deemed necessary.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_3
• /
• pp.2027-2034
• /
• 2021

Using multi-temporal KOMPSAT-3/3A high-resolution satellite images, the Normalized Difference Vegetation Index (NDVI) for the area around the Fukushima daiichi nuclear power plant was determined, and the pattern of vegetation changes was analyzed. To calculate the NDVI, surface reflectance from the KOMPSAT-3/3A satellite image was used. Satellite images from four years were used, and the zones where the images overlap was designated as the area of interest (AOI) for the study, and by setting a profile passing through highly vegetated area as a data analysis method, the changes by year were examined. In addition, random points were extracted within the AOI and displayed as a box plot to quantitatively indicate change of NDVI distribution pattern. The main results of this study showed that the NDVI in 2014 was low within AOI in the vicinity of the nuclear power plant, but vegetated area continued to expand until 2021. These results were also confirmed in the change monitoring results shown in a profile or box plot. In disaster areas where access is restricted, such as the Fukushima nuclear power plant area, where it is difficult to collect field data, obtaining land cover classification products with high accuracy using satellite images is challenging, so it is appropriate to analyze them using primary outputs such as vegetation indices obtained from high-resolution satellite imagery. It is necessary to establish an international cooperation system for jointly utilizing satellite images. Meanwhile, to periodically monitor environmental changes in neighboring countries that may affect the Korean peninsula, it is necessary to establish utilization models and systems using high-resolution satellite images.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.151-152
• /
• 2018

In the domestic nuclear power industry, concern about safety of nuclear power plants is continuously increased with the Fukushima nuclear power plant accident. In order to enhance the safety of nuclear power plants, it is important to ensure that the power plants are operating with proper margin within the original design bases. Margin management is the process of ensuring that the NPP designer and operator are aware of the physical and operating limits, and potential and probability of failure, for each component in the plant. All components are subject to margin considerations, but the most important components by scope and attention are those related to safety-related systems and NPP safe shutdown.

• Korean Journal of Environmental Biology
• /
• v.29 no.4
• /
• pp.373-378
• /
• 2011

Our aim was to investigate the genotoxicity of ambient air in the Krak$\acute{o}$w area after Fukushima Nuclear Power Plant (NPP) accident and compare with results from Chernobyl fallout. For the detection of ambient air genotoxicity the technique for screening gene mutation frequency in somatic cells of the $Tradescantia$ stamen hairs ($Trad$-SH assay) was used. Since 11th of March 2011 (Fukushima NPP accident), several pots containing at least 15 shoots of bioindicating plants were exposed to ambient air at 2 sites in the Krak$\acute{o}$w surrounding area, one in the city center, and about 100 pots in a control site (in the glasshouse of the Institute of Nuclear Physics) Continuous screening of mutations was performed. Progenies of 371,090 cells exposed were analyzed. Mutation frequency obtained in the first 10 days has shown a mean control level (GMF*100=$0.06{\pm}0.01$). At scoring period related to influence of a potential Fukushima fallout, a significant increase of gene mutation frequencies above the control level was observed at each site in the range, 0.10~0.33 depending on the location, (mean value for all sites GMF*100=$0.19{\pm}0.05$) that was associated with a strong expression of toxic effects. In the reported studies following the Chernobyl NPP accident monitoring $in$ $situ$ of the ambient air genotoxicity was performed in the period since April $29^{th}$ till June $3^{rd}$ 1986 also with Trad-SH bioindicator. In general, mutation frequency increases due to Chernobyl fallout(GMF*100=$0.43{\pm}0.02$) were corresponding to fluctuation of radioactivity in the air reported from physical measures, and to published reports about increase in chromosome aberration levels. Although, recent data obtained from monitoring of the ambient air quality in the Krak$\acute{o}$w and surroundings are lower when compared to results reported after Chernobyl NPP accident, though results express a significant increase above the control level and also are corresponding with increased air radioactivity reported from physical measurements. Statistically significant in comparison to control increase in gene mutation rates and more prolonged than that after Chernobyl fallout increase of GMF was observed during the period following the Fukushima NPP failure.

• Journal of Radiation Protection and Research
• /
• v.41 no.1
• /
• pp.7-14
• /
• 2016

Background: The objective of this study was to investigate Korean people's awareness about impact of the Fukushima nuclear power plant accident in Japan and radioactive contamination caused by it. Materials and Methods: The respondents of the survey were 600 adults who resided in the Seoul metropolitan area. Results and discussion: The survey results show that the majority of respondents were concerned about impact of radiation leakage that might have an effect on our environment. They were worried about radioactive contamination of foodstuffs, particularly fishery products and preferred to acquire information through TV(49.8%) or the Internet(31.3%). Meanwhile, respondents mentioned that the information on the Fukushima nuclear accident and radioactive contamination had not been sufficient and they didn't know well about the follow-up measures of the government on the accident. Most respondents answered that information on radioactive contamination levels and safety of foods and environment was most needed. Conclusion: The results of this study could be useful to enhance awareness on radioactivity and improve risk communication on nuclear power plant accidents.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.20 no.3
• /
• pp.339-347
• /
• 2022

Major accidents at nuclear power plants generate huge amounts of radioactive waste in a short period of time over a wide area outside the plant boundary. Therefore, extraordinary efforts are required for safe management of the waste. A well-established remediation plan including radioactive waste management that is prepared in advance will minimize the impact on the public and environment. In Korea, however, only limited plans exist to systematically manage this type of off-site radioactive waste generating event. In this study, we developed basic strategies for off-site radioactive waste management based on recommendations from the IAEA (International Atomic Energy Agency) and NCRP (National Council on Radiation Protection and Measurements), experiences from the Fukushima Daiichi accident in Japan, and a review of the national radioactive waste management system in Korea. These strategies included the assignment of roles and responsibilities, development of management methodologies, securement of storage capacities, preparation for the use of existing infrastructure, assurance of information transparency, and establishment of cooperative measures with international organizations.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.376-385
• /
• 2021

Probabilistic risk assessment (PRA) has improved its elemental technologies used for assessing external events since the Fukushima Daiichi Nuclear Power Station Accident in 2011. HRA needs to be improved for analyzing tasks performed under extreme conditions (e.g., different actors responding to external events or performing operations using portable mitigation equipment). To make these improvements, it is essential to understand plant-specific and scenario-specific conditions that affect human performance. The Nuclear Risk Research Center (NRRC) of the Central Research Institute of Electric Power Industry (CRIEPI) has developed an HRA guide that compiles qualitative analysis methods for collecting plant-specific and scenario-specific conditions that affect human performance into "narratives," reflecting the latest research trends, and models for analysis of tasks under extreme conditions.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.18 no.2
• /
• pp.195-206
• /
• 2020

Although the national radiological emergency response system has been improved by incorporating lessons from the Fukushima nuclear power plant accident and recent domestic natural disasters, it has not fully incorporated these lessons. In addition, it cannot deal with a variety of aftermath of the radiological disaster. Even for the same disaster, the national emergency response system should comply with multiple domestic laws in our country. Furthermore, there are a few discrepancies between the articles of the domestic laws that the national radiological emergency response system should address. Therefore, this study investigates the characteristics of radiological disasters, examines articles on the domestic laws related to the national radiological emergency response system, and analyses the Japanese government's responses to the Fukushima nuclear power plant accident. Based on the results of the review, suggestions for the improvement of the national radiological emergency response system in terms of response organization and framework have been proposed in this study.