• Journal of Radiation Industry
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• v.9 no.4
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• pp.209-216
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• 2015

It has been about 5 years since the Fukushima nuclear power plant accident, which contaminated large area with radioactive materials. It is necessary to assess radiation dose to establish evacuation areas and to set decontamination goal for the large contaminated area. In this study, we assessed temporal trend of radiation dose to the public living in the large area contaminated with radioactive materials after the Fukushima nuclear power plant accident. The dose assessment was performed based on Chernobyl model and RESRAD model for two evacuation lift areas, Kawauchi and Naraha. It was reported that deposition densities in the areas were $4.3{\sim}96kBq\;m^{-2}$ for $^{134}Cs$, $1.4{\sim}300kBq\;m^{-2}$ for $^{137}Cs$, respectively. Radiation dose to the residents depended on radioactive cesium concentrations in the soil, ranging $0.11{\sim}2.4mSv\;y^{-1}$ at Kawauchi area and $0.69{\sim}1.1mSv\;y^{-1}$ at Naraha area in July 2014. The difference was less than 5% in radiation doses estimated by two different models. Radiation dose decreased with calendar time and the decreasing slope varied depending on dose assessment models. Based on the Chernobyl dosimetry model, radiation doses decreased with calendar time to about 65% level of the radiation dose in 2014 after 1 year, 11% level after 10 years, and 5.6% level after 30 years. RESRAD dosimetry model more slowly decreased radiation dose with time to about 85% level after 1 year, 40% level after 10 years, and 15% level after 30 years. The decrease of radiation dose can be mainly attributed into radioactive decays and environmental transport of the radioactive cesium. Only environmental transports of radioactive cesium without consideration of radioactive decays decreased radiation dose additionally 43% after 1 year, 72% after 3 years, 80% after 10 years, and 83% after 30 years. Radiation doses estimated with cesium concentration in the soil based on Chernobyl dosimetry model were compared with directly measured radiation doses. The estimated doses well agreed with the measurement data. This study results can be applied to radiation dose assessments at the contaminated area for radiation safety assurance or emergency preparedness.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2511-2521
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• 2020

The Fukushima accident is characterized by the fact that three reactors at the same site experienced reactor vessel failure and the accident resulted in significant radiological release to the environment, which was about 1/10 of the Chernobyl releases. The safe removal of fuel debris in the reactor vessel and Primary Containment Vessel (PCV) and treatment of huge amount of contaminated water are the major issues for the decommissioning in coming decades. Discussions on the new researches efforts being carried out in the area of investigation of the end state of fuel debris and Boling Water reactor (BWR) specific core melt progression, development of technologies for the mitigation of radiological releases to comply with the strengthened safety requirement set after the Fukushima accident are discussed.

• Journal of the Korean Institute of Intelligent Systems
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• v.7 no.1
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• pp.5-15
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• 1997

This paper mentions a fault tree analysis using not probability but natural language and fuzzy theory, Reliability estimate of each basic event and dependence level estimate among subsystems are expressed by linguistic terms. Analysis results are also expressed by natural language. The meaning of linguistic terms is expressed by a fuzzy set. In the presented analysis approach parametrized operations of fuzzy sets are considered so that analyst's subjectivity can be introduced into the analysis. This paper gives the Chernobyl accident as an example of the fuzzy fault tree analysis using linguistic terms.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.398-398
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• 2004

• Environmental and Resource Economics Review
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• v.26 no.2
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• pp.139-172
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• 2017

Nuclear safety measures such as safety technology, culture, and regulation affects nuclear performances. This paper analyzes the change of nuclear performance by considering nuclear safety measures. Nuclear performance and technical data ranging 1970 to 2015 are collected from the Power Reactor Information System (PRIS) of IAEA. The result of panel regression analysis shows that overall engineering level, maintenance engineering and productivity decrease the forced loss rate (FLR). FLR structurally increase after Chernobyl accident in 1986 whereas after TMI and Fukushima accidents FLR didn't show any significant changes. The structural increase of FLR after Chernobyl are likely to result from the efforts of international communities for nuclear safety culture which makes nuclear operating company pay more opportunity cost to achieve nuclear safety.

• Journal of the Ergonomics Society of Korea
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• v.35 no.4
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• pp.247-261
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• 2016

Objective:The aim of this paper is to discuss the nuclear safety culture in Korea. Background: Recently, Korean nuclear field has met a strong anti-nuclear trend after a few happenings, as well as Fukushima accident, which are turned out to be caused by organizational pitfalls and safety culture defects in general. Method: We review the concepts and constructs of safety culture based on the brief history of the nuclear safety culture that IAEA mainly raised after the Chernobyl accident in 1986. Additionally, we give a comparative discussion on the approach to the safety culture with U.S. Results: Finally, we discuss the three technical domains and propose six selected domestic issues related to the nuclear safety culture for coping with the demanding requests on nuclear safety in Korea. Conclusion and Application: We suggest several recommendations and a research direction in the form of a re-start line for the nuclear safety culture in Korea.

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.85-91
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• 2011

Safety in the nuclear facility has been a growing interest due to recent recurrences of the fatal accidents such as Fukushima accident and Chernobyl accident. It is not easy to determine the extent to what technical requirements of nuclear facility such as nuclear power plant are be likely applicable to the laboratory for use of nuclear material. All of workers in nuclear shall be recognized for the generic features of safety according to the related laws. This study surveys a status of safety control laws to enhance safety in laboratory for use of nuclear material.

• Asian Journal for Public Opinion Research
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• v.2 no.3
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• pp.172-195
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• 2015

Multiple nationwide opinion surveys, carried out by the government (cabinet office), major media (national newspapers and NHK), the National Institute for Environmental Studies, and the Atomic Energy Society of Japan, have revealed that the Fukushima nuclear accident has heightened people's perception of disaster risks, fear of nuclear accidents, and increased recognition of pollution issues, and has changed public opinion on nuclear energy policy. The opinion gap on nuclear energy policy between specialists and lay people has widened since the disaster. The results of the Japanese General Social Survey data show that objections to the promotion of nuclear energy are strong among females, and weaker among young males and the supporters of the LDP. These findings are similar to the data collected after the Chernobyl accident. People who live in a 70km radius of nuclear plants tend to evaluate nuclear disaster risks higher. Distance from nuclear plants and the perception of earthquake risk interactively correlate with opinions on nuclear issues. Among people whose evaluation of earthquake risk is low, those who live nearer to the plants are more likely to object to the abolishment of nuclear plants. It was also found that the nuclear disaster has changed people's behavior; they now try to save electricity. The level of commitment to energy saving is found to relate to opinions on nuclear issues.

• Journal of Radiation Protection and Research
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• v.21 no.3
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• pp.217-253
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• 1996

Following after the Chernobyl accident. the response to the large scale nuclear accidents became a clear example to show how these accidents affect the public information that strongly depend on political, economical, and social factors. Futhermore, in present day although we live in the era of various information, as far as the problem of nuclear is concerned, the acceptance of the source of Information is always apt to limited. Therefore, in this investigations, as a case study, an attempt is to make the method of minimizing and a preparation to cope with the grope of countermeasure for psychologically unsettled and disordered problems that accepted from both of the unconfirmed and of the exaggerated circumstantial report of mass media as well as a clue to the probability under the condition of existence of major and minor nuclear accidents. In the present paper, it also intends to establish the terminology that covered all the part of nuclear field use in a writing guideline to the scientific column of nuclear accident as shown in the table. and several methodology in relation to the report tendency of mass communication in nuclear accident and the standpoint of public acceptance from a intrinsic point of view are discussed.

• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.184-193
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• 2021

Background: The radionuclides released by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident 9 years ago are still being monitored by various research teams and the Japanese government. Comparison of different surveys' results could help evaluate the exposure doses and the mechanism of radiocesium behavior in the urban environment in the area. In this study, we clarified the relationship between land use and temporal changes in the ambient dose rates (air dose rates) using big data. Materials and Methods: We set a series of 1 × 1 km² meshes within the 80 km zone of the FDNPP to compare the different survey results. We then prepared an analysis dataset from all survey meshes to analyze the temporal change in the air dose rate. The selected meshes included data from all survey types (airborne, fixed point, backpack, and carborne) obtained through the all-time survey campaigns. Results and Discussion: The characteristics of each survey's results were then evaluated using this dataset, as they depended on the measurement object. The dataset analysis revealed that, for example, the results of the carborne survey were smaller than those of the other surveys because the field of view of the carborne survey was limited to paved roads. The location factor of different land uses was also evaluated considering the characteristics of the four survey methods. Nine years after the FDNPP accident, the location factor ranged from 0.26 to 0.49, while the half-life of the air dose rate ranged from 1.2 to 1.6. Conclusion: We found that the decreasing trend in the air dose rate of the FDNPP accident was similar to the results obtained after the Chernobyl accident. These parameters will be useful for the prediction of the future exposure dose at the post-accident.