• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.11
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• pp.1027-1033
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• 2010

A two-phase (gas-liquid) flow is a common phenomenon in fluidic systems, e.g., fluidic systems in the electro-magnetic or nuclear power generation industry and in the steel industry. The measurement of a two-phase flow is important for guaranteeing the safety of the system and for achieving the desired performance. The measurement of the void fraction, which is one of the parameters of the two-phase flow that determines the pressure drop and heat transfer coefficient, is very important. The time resolution achieved by employing the impedance method that can be used to calculate the void fraction from the impedance of the fluid is high because the electric characteristics are taken into account. Therefore, this method can be employed to accurately measure the void fraction without distortion of flow in real time by placing electrodes on the walls of the tubes. Coney analytically studied a ring-type impedance meter, which can be employed in a circular tube. The aim of this study is to experimentally verify the robustness of a three-ring impedance meter to variations in the electric conductivity of the fluid; this robustness was suggested by Coney but was not experimentally verified.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.151-159
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• 2017

A deep geological disposal at a depth of 500 m in stable host rock is considered to be the safest method with current technologies for disposal of spent fuels classified as high-level radioactive waste. The most important requirement is that the temperature of the bentonite buffer, which is a component of the engineered barrier, should not exceed $100^{\circ}C$. In Korea, the amount of spent fuel generated by nuclear power generation, which accounts for about 30% of the total electricity, is continuously increasing and accumulating. Accordingly, the area required to dispose of it is also increasing. In this study, various duplex disposal concepts were derived for the purpose of improving the disposal efficiency by reducing the disposal area. Based on these concepts, thermal analyses were carried out to confirm whether the critical disposal system requirements were met, and the thermal stability of the disposal system was evaluated by analyzing the results. The results showed that upward 75 m or downward 75 m apart from the reference disposal system location of 500 m depth would qualify for the double layered disposal concept. The results of this study can be applied to the establishment of spent fuel management policy and the design of practical commercial disposal system. Detailed analyses with data of a real disposal site are necessary.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.17 no.4
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• pp.437-445
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• 2019

After the permanent shutdown of K1 in 2017, decommissioning processes have attracted great attention. According to the current decommissioning roadmap, the dismantling of the activated components of K1 may start in 2026, following the removal of its spent fuel. Since the reactor vessel (RV) and reactor vessel internal (RVI) of K1 contain massive components and are relatively highly activated, their decommissioning process should be conducted carefully in terms of radiological and industrial safety. For achieving maximum efficiency of nuclear waste management processes for K1, we present activation analysis of the segmentation process and waste classification of the RV and RVI components of K1. For RVI, the active fuel regions and some parts of the upper and lower active regions are classified as intermediate-level waste (ILW), while other components are classified as low-level waste (LLW). Due to the RVI's complex structure and high activation, we suggest various underwater segmentation techniques which are expected to reduce radiation exposure and generate approximately nine ILW and nineteen very low level waste (VLLW)/LLW packages. For RV, the active fuel region and other components are classified as LLW, VLLW, and clearance waste (CW). In this case, we suggest in-situ remote segmentation in air, which is expected to generate approximately forty-two VLLW/LLW packages.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.367-373
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• 2017

The O2O service is an efficient way to operate based on systematic connection of the offline and online states. At present, education, health checkups, and exposure management of radiation workers are separated from offline and online at nuclear-related workplaces. Therefore, we developed a radiation workers management program at the workplace and tried to link online and offline states. After applying the program to the local network, we developed a written employee management system as a computer program and applied it to radiation workers and radiation safety managers at a university hospital in Daejeon using a questionnaire. As a result of the survey, the results of this program can enhance the awareness of safety management and work convenience. There is also a demand for radiation closed workers as well as radiation relative workers. It will be necessary to collect opinions regarding the characteristics of each workplace for the generalization of the radiation workers management program. As a result, real-time radiation safety management and work improvement can be expected through network connections between the workplace, supervisory authority, and related organizations in the future. If a circle structure is formed using the employee management program, development of radiation safety management can be expected.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1255-1262
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• 2012

Look into the nuclear power plant of Wolsong currently, it is controlled in order to required operating pressure with PI controller. PI controller has a simple structure and satisfy design requirements to gain setting. However, It is difficult to control without changing the gain from produce changes in parameters such as loss of the valves and the pipes. To solve these problems, the dynamic change of the PI controller gain, or to compensate for the PI controller output is desirable to configure the controller. The aim of this research and development in the parameter variations can be controlled to a stable controller design which is reduced an error and a vibration. Proposed PI/NN control techniques is the PI controller and the neural network controller that combines a parallel and the neural network controller part is compensated output of the controller for changes in the parameters were designed to be robust. To directly evaluate the controller performance can be difficult to test in real processes to reflect the characteristics of the process. Therefore, we develope the simulator model using the real process data and simulation results when compared with the simulated process characteristics that showed changes in the parameters. As a result the PI/NN controller error and was confirmed to reduce vibrations.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2005.11a
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• pp.126-133
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• 2005

Securing of radioactive waste disposal site and the related operations for disposal of low and intermediate level radioactive waste is being actively carried out in Korea. For disposal of radioactive wastes, physicochemical and radiological status and integrity of radioactive wastes must be secured first. Also, waste generators must provide this information to disposers. In addition, to secure the safety of waste disposal, waste acceptance criteria (WAC) and site specific waste acceptance criteria (SWAC) to consider characteristics of the disposal site are required. Radioactive wastes must be processed, generated, managed and transferred in accordance with these criteria. [1] For this, evaluation of properties on each of the radioactive wastes must be performed. However, in reality, atomic power plants are experiencing difficulties in relation to this due to the large quantity of radioactive waste generation. In order to solve this problem, IAEA and major overseas countries have developed, thus are using waste certification program (WCP) and quality assurance program (QAP) [2,3]. On the basis of these programs, radioactive waste certification program has been developed for safe disposal of radioactive wastes in Korea to satisfy the provisions specified in 'low and intermediate level radioactive waste transfer guidelines' of announcement No. 2005-18 from the Ministry of Science and Technology and specific site waste acceptance criteria (tentative plan). In addition, it is being planned to administer amendment on commercial atomic power plant related procedures and ensile staff training in order for early introduction and operation of radioactive waste certification system.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.381-390
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• 2017

In Korea, commercial nuclear power plants and research reactors have on-site storage systems for the spent nuclear fuel, but it is difficult to expand the facilities used for the storage systems. If decommissioning of nuclear power plants starts, an amount of high level radioactive waste will be generated. In this study, a radiological impact assessment of the railroad transport of high level radioactive waste was carried out considering radiation workers and the public, using the developed transport container as the transport package. The dose rates for workers and the public during the transport period were estimated, considering anticipated transport scenarios, and the results compared with the regulatory limit. A sensitivity analysis was also carried out by considering the different release ratios of the radioactive materials in the high level radioactive waste, and different distances between the transport container and workers during loading and unloading phases and while attaching another freight car. For all the anticipated transport scenarios, the radiological impacts for workers and the public met the regulatory limits.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.333-341
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• 2017

The Korea Atomic Energy Research Institute (KAERI) constructed the PyRoprocessing Integrated inactive Demonstration facility (PRIDE) to carry out experiments on engineering scale pyroprocessing. PRIDE has a large processing cell that human workers are not allowed to access, and thus the equipment inside is operated from outside using remote handling systems. It is therefore essential to examine the operability and maintainability of the equipment in view of remote handling systems, and the equipment is thoroughly examined in a mockup cell before it is installed in the processing cell. If the equipment is tested in a virtual mockup rather than in a mockup cell, the development cost can be significantly reduced. The PRIDE 3D simulator was integrated for virtual verification of equipment that will be installed in the processing cell. All remote handling devices in the actual PRIDE were also virtually installed in the PRIDE 3D simulator. The 3D model of the equipment was loaded and located in the exact position in the virtual processing cell. A scenario to replace an actual electrode was implemented in the PRIDE 3D simulator. The design of the equipment and the working procedures in the scenario were successfully evaluated. The results demonstrated that the PRIDE 3D simulator can be used successfully as an alternative to actual mockup testing.

• Korean Security Journal
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• no.59
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• pp.217-242
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• 2019

Nowadays, Terrorism has become bloodier. Unlike the past, the recent terrorism has been indiscriminate in the purpose of mass- killing. Given this aspect, the threat of a CBRN attack is the biggest one to modern society. Notably, the possibility of terrorist attacks in Korea by international terrorist groups such as ISIL is higher than ever in consideration of its allusion; crusades and the devil's allied forces. To overcome these circumstances, various measures have been taken for counter terrorism at the state level including anti-terrorist legislation. Under the anti-terrorist act, police have to lead relevant inter agencies when it comes to the CBRN terror. At first glance, current countermeasures would work well. However, in order to respond quickly, the standing cooperations system of related departments need to be set up. In this sense, this article proposed a coagulatory body that could not only consider institutional-oriented organizational restructuring and response but also integrate and operate functions of various specialized institutions. It also stressed that the council should move toward a consultative body of information gathering, distribution and working- level consultation. With this cooperation system, counter-terrorism agencies can respond rapidly, stop wasting their effort and assets by about 30%. Also, they could design the atypical aspect of terrorism into standardized.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.1
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• pp.37-45
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• 2012

In an effort to further exploit the peak ground-motion acceleration (PGA) information per second available in real time by the enacted law, bracketed summations of the PGA per second ($BSPGA_k$) for 30 seconds based on the records with a rate of 100 samples were compared with the cumulative absolute velocity (CAV) and earthquake intensities based on a worldwide database of records from small-to-large earthquakes. The CAV, currently in use as an earthquake damage indicator for nuclear power plants due to its strong correlation with the earthquake intensity, has the disadvantage of requiring a massive amount of digital data with a rate of more than 100 samples per second. The comparative study shows that the $BSPGA_k$ is well correlated with the CAV over the wide range of strong ground-motion levels, which suggests that the $BSPGA_k$ is one of the new promising ground-motion parameters especially useful for rapid earthquake alert notifications through an earthquake monitoring network. Based on the domestic database of records from small-to-moderate earthquakes with felt reports, it is also observed that the $BSPGA_k$ is comparable to the CAV and better than the PGA in predicting the intensity by using the correlation relation.