• Journal of the Society of Disaster Information
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• v.17 no.3
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• pp.500-511
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• 2021

Purpose: This study seeks to draw out implications that must be considered in the process of establishing measures to evacuate residents in preparation for domestic nuclear disasters by conducting an investigation about the disaster situation at the time of the Fukushima nuclear power plant explosion, emergency warning situation for residents protection, evacuation situation and In addition to investigating problems and measures raised in the resident protection system at that time. Method: A literature survey was conducted focusing on reports published by Japan's national, parliament, local governments and related agencies from right after the Great East Japan Earthquake to the present. Result: Found out what needs to be considered in the process of establishing domestic radiation disaster measures through the results of the survey on the problems and countermeasures derived from the process of evacuation of residents at the time of the Fukushima nuclear power plant explosion. Conclusion: The reviews were classified into four categories and detailed reviews were presented.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.133-140
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• 2016

Backgrounds: The accident at Fukushima Daiichi Nuclear Power Plant (NPP), March 2011, caused serious radioactive contamination over wide area in east Japan. Therefore, it is important to know the effect of the accident and the status of NPP. Materials and Methods: This paper provides a review on the status of radiation dose and radioactive contamination caused by the accident on the basis of publicized information. Results and Discussion: Monitoring of radiation dose and exposure dose of residents has been conducted extensively by the governments and various organizations. The effective dose of general residents due to the accident proved to be less than a mSv both for external and internal dose. The equivalent committed dose of thyroid was evaluated to be a few mSv in mean value and less than 50 mSv even for children. Monitoring of radioactivity concentration has been carried out on food ingredients, milk and tap water, and actual meal. These studies indicated the percentage of foods above the regulation standard was over 10% in 2011 but decreasing steadily with time. The internal dose due to foods proved to be tens of ${\mu}Sv$ and much less than that due to natural $^{40}K$ even in the Fukushima area and decreasing steadily, although high level concentration is still observed in wild plants, wild mushrooms, animals and some kind of fishes. Conclusion: According to extensive studies, not only the effect of the accident but also the pathway and countermeasures against radioactive contamination have been revealed, and they are applied very effectively for restoration of environment and reconstruction of the area.

• Nuclear Engineering and Technology
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• v.45 no.5
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• pp.625-636
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• 2013

Pressing demands of economic competitiveness, the need for large-scale deployment, minimizing the need of human intervention, and experience from the past events and incidents at operating reactors have guided the evolution and innovations in reactor technologies. Indian innovative reactor 'AHWR' is a pressure-tube type natural circulation based boiling water reactor that is designed to meet such requirements, which essentially reflect the needs of next generation reactors. The reactor employs various passive features to prevent and mitigate accidental conditions, like a slightly negative void reactivity coefficient, passive poison injection to scram the reactor in event of failure of the wired shutdown systems, a large elevated pool of water as a heat sink inside the containment, passive decay heat removal based on natural circulation and passive valves, passive ECC injection, etc. It is designed to meet the fundamental safety requirements of safe shutdown, safe decay heat removal and confinement of activity with no impact in public domain, and hence, no need for emergency planning under all conceivable scenarios. This paper examines the role of the various passive safety systems in prevention and mitigation of severe plant conditions that may arise in event of multiple failures. For the purpose of demonstration of the effectiveness of its passive features, postulated scenarios on the lines of three major severe accidents in the history of nuclear power reactors are considered, namely; the Three Mile Island (TMI), Chernobyl and Fukushima accidents. Severe plant conditions along the lines of these scenarios are postulated to the extent conceivable in the reactor under consideration and analyzed using best estimate system thermal-hydraulics code RELAP5/Mod3.2. It is found that the various passive systems incorporated enable the reactor to tolerate the postulated accident conditions without causing severe plant conditions and core degradation.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.31-34
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• 2013

According to the increase in numbers and operation time of domestic Nuclear Power Plants, KHNP(Korea Hydro & Nuclear Power) has many operating experiences. These show that most of the accidents repeatedly occurred not by the new sources or mechanism like the Fukushima Accident, but by the human and equipment errors from normal habits, process, design, maintenance etc.. These lessons show that the well-established systematic approach is requested to take lessons from past experiences. For this reason, developed countries established INPO, WANO, COG as a non-profit professional organizations to actively share their operating experiences. KHNP is also trying to promote the utilization of operating experiences. As part of this effort, KHNP is developing the KHNP-JIT, reflecting the overseas JIT and the domestic experiences.

• Environmental and Resource Economics Review
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• v.22 no.2
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• pp.367-391
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• 2013

After the Fukushima nuclear accident, the external costs of generating electricity from nuclear power plants such as additional safety compliance costs and possible accident risk action costs have gained increasing attention from the public, policy-makers and politicians. Consequently, estimates of the external costs of nuclear power are very deliberate issue that is at the center of the controversy in Korea. In this paper, we try to calculate the external costs associated with the safety of the nuclear power plants, particularly focusing on additional safety compliance costs and possible accident risk action costs. To estimate the possible accident risk action costs, we adopt the damages expectation approach that is very similar way from the external cost calculation of Japanese government after the Fukushima accident. In addition, to estimate additional safety compliance costs, we apply the levelized cost of generation method. Furthermore, we perform the sensitivity analysis to examine how much these social costs increase the electricity price rate. Estimation results of the additional security measure cost is 0.53Won/kWh ~ 0.80Won/kWh depending on the capacity factor, giving little change on the nuclear power generation cost. The estimates of possible accident risk action costs could be in the wide range depending on the different damages of the nuclear power accident, probability of the severe nuclear power accident and the capacity factor. The preliminary results show that it is 0.0025Won/kWh ~ 26.4188Won/kWh. After including those two external costs on the generation cost of a nuclear power plant, increasing rate of electricity price is 0.001%~10.0563% under the capacity factor from 70% to 90%. This paper tries to examine the external costs of nuclear power plants, so as to include it into the generation cost and the electricity price. This paper suggests one of the methodologies that we might internalize the nuclear power generations' external cost, including it into the internal generation cost.

• Journal of Radiation Protection and Research
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• v.44 no.4
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• pp.128-148
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• 2019

Massive environmental monitoring has been conducted continuously since the Fukushima Daiichi Nuclear Power accident in March of 2011 by different monitoring methods that have different features together with migration studies of radiocesium in diverse environments. These results have clarified the characteristics of radiological environments and their temporal change around the Fukushima site. At three months after the accident, multiple radionuclides including radiostrontium and plutonium were detected in many locations; and it was confirmed that radiocesium was most important from the viewpoint of long-term exposure. Radiation levels around the Fukushima site have decreased greatly over time. The decreasing trend was found to change variously according to local conditions. The air dose rates in environments related to human living have decreased faster than expected from radioactive decay by a factor of 2-3 on average; those in pure forest have decreased more closely to physical decay. The main causes of air dose rate reduction were judged to be radioactive decay, movement of radiocesium in vertical and horizontal directions, and decontamination. Land-use categories and human activities have significantly affected the reduction tendency. Difference in the air dose rate reduction trends can be explained qualitatively according to the knowledge obtained in radiocesium migration studies; whereas, the quantitative explanation for individual sites is an important future challenge. The ecological half-lives of air dose rates have been evaluated by several researchers, and a short-term half-life within 1 year was commonly observed in the studies. An empirical model for predicting air dose rate distribution was developed based on statistical analysis of an extensive car-borne survey dataset, which enabled the prediction with confidence intervals. Different types of contamination maps were integrated to better quantify the spatial data. The obtained data were used for extended studies such as for identifying the main reactor that caused the contamination of arbitrary regions and developing standard procedures for environmental measurement and sampling. Annual external exposure doses for residents who intended to return to their homes were estimated as within a few millisieverts. Different forms of environmental data and knowledge have been provided for wide spectrum of people. Diverse aspects of lessons learned from the Fukushima accident, including practical ones, must be passed on to future generations.

• The Journal of Engineering Geology
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• v.24 no.4
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• pp.609-613
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• 2014

The Korean Peninsula, located at the southeastern tip of the Eurasian Plate, is known to be tectonically stable, and no critical evidence has yet been found that would override the safety design of nuclear facilities in South Korea. Because a nuclear power plant, like other major social overhead capital facilities, could cause great damage to both the environment and society through an unexpected tectonic event, even one of extremely low probability, like the Fukushima accident, a defense-in-depth safety approach is required in geological and geotechnical site safety evaluation for nuclear projects. This paper introduces the regulatory procedures that are in place to confirm nuclear site safety and site monitoring (e.g., earthquakes and groundwater) systems applied to nuclear facilities in order to reduce inherent uncertainties within the site safety review of geological and seismological issues related with a NPP project.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.234-240
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• 2016

We examined the diffusion of contaminants released from the southern coast around Fukushima, Japan, during the passage of typhoons using a three-dimensional numerical model (POM) to track diffusing radioactivity (RA) released from the nuclear power plant at Fukushima following the accident caused by the giant tsunami event in March 2011. Radioactive contaminants released during the passage of typhoons may have significantly affected not only Japanese but also Korean coastal waters. The model domain covered most of the northwestern Pacific including marginal seas such as the East/Japan Sea and the Yellow Sea. Several numerical experiments were conducted case studies focusing on the westward diffusion from the southern coast of Japan of contaminants derived from the source site (Fukushima) according to various attributes of the typhoons, such as intensity, track, etc. The model produced the following results 1) significant amounts of contaminants were transported in a westward direction by easterly winds favorable for generating a coastal air stream along the southern Japanese coast, 2) the contaminants reached as far as Osaka Bay with the passage of typhoons, forced by a 5-day positive sinusoidal form with a (right-) northward track east of Fukushima, and 3) the range of contamination was significant, extending to the interior of the East/Japan Sea around the Tsugaru Strait. The model suggests that contaminants and/or radioactivity released from Fukushima with the passage of typhoons can affect Korean waters including the northeastern East/Japan Sea around the Tsugaru Strait, especially when the typhoon tracks are favorable for generating a westward coastal air stream along the southern Japanese coast.

• 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.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.177-179
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• 2018

After Fukushima nuclear accident at 2011, nuclear industrial has been focused on operation and maintenance phase, not design and construction phase. Continued good operating performance of nuclear power plants has been the best critical issue to nuclear utilities. Replacement for complete components as well as parts of components is being procured because nuclear utilities must maintain safety and reliability of operating nuclear power plants. However, many suppliers and manufacturers are giving up a nuclear quality assurance program under reduction in new construction of nuclear power plants. It is able to be increased difficulty in procuring spare parts to support operations and maintenance of nuclear power plants. Over 20% of nuclear power plant equipment in some countries is obsolete. Owing to obsolescence of nuclear safety-related items and/or withdrawing a nuclear quality assurance program of suppliers and manufactures, some replacement item and part might be procured to the item not covered by appendix B to USNRC 10 CFR Part 50. Under various methods of the nuclear repair and replacement methodology, utilities are supposed to establish a typical program for a repair and replacement of an electrical equipment and its parts in conjunction with a nuclear quality assurance. Concerning this typical program, this study suggests the repair and replacement methodology of electrical equipments used in nuclear power plants by procurement of a power supply, based on nuclear regulations, codes, standards, guidelines, specific and general technical information, etc..