With the aging of nuclear power plants (NPPs) in 37 countries around the world, 207 out of 437 NPPs have been permanently shutdown as of August 2022 according to the IAEA. In Korea, the decommissioning of NPPs is emerging as a challenge due to the permanent shutdown of Kori Unit 1 and Wolsong Unit 1. However, there are no cases of decommissioning activities for Heavy Water Reactor (HWR) such as Wolsong Unit 1 although most of the decommissioning technologies for Light Water Reactor (LWR) such as Kori Unit 1 have been developed and there are cases of overseas decommissioning activities. This study shows the development of a decommissioning waste amount/cost/process linkage program for decommissioning Pressurized Heavy Water Reactor (PHWR), i.e. CANDU NPPs. The proposed program is an integrated management program that can derive optimal processes from an economic and safety perspective when decommissioning PHWR based on 3D modeling of the structures and digital mock-up system that links the characteristic data of PHWR, equipment and construction methods. This program can be used to simulate the nuclear decommissioning activities in a virtual space in three dimensions, and to evaluate the decommissioning operation characteristics, waste amount, cost, and exposure dose to worker. In order to verify the results, our methods for calculating optimal decommissioning quantity, which are closely related to radiological impact on workers and cost reduction during decommissioning, were compared with the methods of the foreign specialized institution (NAGRA). The optimal decommissioning quantity can be calculated by classifying the radioactivity level through MCNP modeling of waste, investigating domestic disposal containers, and selecting cutting sizes, so that costs can be reduced according to the final disposal waste reduction. As the target waste to be decommissioning for comparative study with NAGRA, the calandria in PHWR was modeled using MCNP. For packaging waste container, NAGRA selected three (P2A, P3, MOSAIK), and we selected two (P2A, P3) and compared them. It is intended to develop an integrated management program to derive the optimal process for decommissioning PHWR by linking the optimal decommissioning quantity calculation methodology with the detailed studies on exposure dose to worker, decommissioning order, difficulty of work, and cost evaluation. As a result, it is considered that it can be used not only for PHWR but also for other types of NPPs decommissioning in the future to derive optimal results such as worker safety and cost reduction.

In the geological disposal system whose host rock is crystalline rock, fractures play a significant role in the safety assessment as they are the main pathway of the radionuclide migration. From the perspective of long-term safety assessment, the properties of fractures can be changed by tectonic movement such as earthquake, uplift, etc. In general, methods for simulating fractures include Discrete Fracture Network (DFN), which directly simulates the fracture surface, and Equivalent Continuous Porous Media (ECPM), which is equivalent to the ratio of the fractures in a certain rock volume. DFN is generally appropriate for deterministic fractures with large scale and high flow velocity, but ECPM may be more appropriate for small scale and sporadically distributed stochastic fractures because the flow velocity is slow and thus the rock matrix diffusion needs to be considered. In fact, several commercial software, such as FracMan, are already in use to convert DFN to ECPM. However, in order to consider the change in properties of fractures due to tectonic movement in the long-term safety assessment, a model that converts DFN to ECPM needs to be modularized and embedded into the safety assessment model. In this study, therefore, an in-house MATLAB code was developed to convert DFN to ECPM, which can be used as a submodule. The algorithm of converting from DFN to ECPM basically followed the Oda’s method. As the first step of the algorithm, in order to obtain the volume ratio of the fracture in a certain mesh element, the cross-sectional area of the fracture and the mesh element was calculated. Then, porosities of each mesh element were calculated as the volume fraction of fractures passing through the mesh element. Based on the Oda’s method, the permeability tensors of each mesh element were calculated by using an empirical fracture tensor which is weighted by the cross-sectional area and transmissivity of each fracture. Finally, the newly developed module was verified by a benchmark test, in which the ECPM results converted from a certain DFN data by using the numerical module developed in this study were compared with those by using FracMan. The newly developed module will be installed in the process-based total system performance assessment framework (APro) being developed by KAERI.

This paper proposes a solution to the out-of band oscillation signal and in-band low transmitter power output that occurrs during the low-temperature operation test for the new mine detector GPR signal transmission and reception module. Tests were performed by applying the optimal values of capacitors and inductors through circuit analysis simulation under the limited space, as a result, it was confirmed that the gain and return loss were improved at all-band thereby preventing oscillation signal and low transmitter power output.

In this study, we intend to develop a control valve with oxidation resistance for hydrogen fluoride that can be applied to the semiconductor production process. Operated Valves currently in use is a form of assembling an air cylinder to the valve body. These valves generally have a cylinder body made of aluminum (Al), so they may corrode depending on the external environment, and the solution leaks along the rod inside the cylinder, causing damage to parts due to corrosion. To solve this problem, the valve plug shape was developed by devising and applying a plug using a valve different from the existing method, and it is possible to block the inflow of hydrogen fluoride into the valve control unit, thereby preventing damage to parts as well as maintaining stable valve operation.

The safety assessment of a geological disposal system is performed over a period of hundreds of thousands of years, during which the activity of radionuclides in spent nuclear fuel decreases to natural radioactivity levels. During this period, the biosphere also experiences the long-term evolution of the surface environment including climate, terrain, and ecosystem changes. These changes cause changes in the water balance, which in turn change the pathways of radionuclides in the subsurface. Therefore, it is essential to consider these long-term changes in the surface environment for a reasonable biosphere safety assessment. For this purpose, this study developed the biosphere assessment module considering the long-term evolution of the surface environment, as a sub-module of APro (Adaptive process-based total system performance assessment framework). As a preceding study, the biosphere assessment module was previously developed using COMSOL for hydraulic and radionuclide transport processes, to simulate the pathway of radionuclides traveling from the shallow aquifer to the surface water body and soil. To consider the long-term evolution of the surface environment, the previous module needed to be improved to apply different water balances as boundary conditions of the module at each snapshot, which is a sub-time period divided based on the surface evolution data. To this end, this study utilized SWAT (Soil and Water Assessment Tool) which calculates the water balance using the surface environmental data including climate, terrain, land cover, and soil type. Conceptually, SWAT calculated annual water balance considering surface environmental changes, and certain components (i.e., groundwater recharge and hydraulic head of water bodies) of water balance were transferred to COMSOL as external data to simulate the pathway of radionuclide transport and spatio-temporal variability of radionuclides. At the current stage, the biosphere computational module has been developed to correspond to its conceptual model, and we plan to further test the applicability of the module using different surface environmental data.

VR은 사용자가 가상 공간에 완전히 몰입하고 상호 작용할 수 있는 가상 세계이다. 본 연구는 스톱모션 애니 메이션을 VR 애니메이션으로 제작할 시 효과적인 객체 표현 방법에 대한 내용을 제시하고자 한다. 실험 결 과 데이터는 VR 스톱모션 애니메이션 및 일반 스톱모션 애니메이션, VR게임 등 다양한 콘텐츠에 적용이 가 능하다. 3D 오프젝트의 변화되는 형태를 앵글별로 3D 스캔한 후 게임엔진에서 다양하게 활용할 수 있도록 데이터화 한 뒤 콘텐츠에 적용하여 구현한다. 기존 스톱모션 애니메이션에서 느낄 수 있는 수작업 느낌을 살리되 디지털적인 이펙트를 추가적으로 이용할 수 있는 장점이 있다. 기존의 스톱 모션 애니메이터들이 접 근하기 힘든 영역을 작업하는데 필요한 세가지 모듈을 구현하여 실험하였다. VR 콘텐츠 제작에서 오브젝트 의 표현과 관련된 분야의 발전에 기여하게 될 것이며 새로운 방향을 제시할 것이다. 향후 연구에서는 각 캐 릭터 관절의 움직임에 따른 3D 스캔 데이터 관련 연구를 수행할 예정이다.

In order to develop a 1 ton truck rear wheel air suspension module, this study designed and manufactured a Z-type spring and air suspension module test jig to optimize the design and reliability of the Z-type spring and vibration-free air suspension module, which are core parts, and to secure the reliability of the developed parts. We were able to achieve the technology development goal of this thesis by making a prototype and conducting a test evaluation at an external test and research institute to perform the vibration endurance test aimed in this study.

Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.