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Daejeon, South Korea

Kim S.M.,Korea Hydro and Nuclear Power Co. | Kim H.T.,Korea Hydro and Nuclear Power Co. | Choi S.S.,Atomic Creative Technology Co.
Canadian Nuclear Society - 31st Annual Conference of the Canadian Nuclear Society and 34th CNS/CNA Student Conference 2010 | Year: 2010

The Wolsong CANDU-6 can be differently treated to a certain extent in terms of operation and safety due to the wide span of commissioning dates between, namely, Unit 1 and Units 2,3,4. This fact resulted in the use of non-unified technical specification (OP&P style in Unit 1 and US standard technical specification style in Units 2,3,4). Thus, it became necessary to improve Limiting Condition for Operations (LCOs) that have been based upon insufficient selection criteria in context of safety standards in the past. The newly developed ISTS for Wolsong CANDU-6 is aimed to achieve the following points, (1) Elimination of unnecessary LCOs that are irrelevant to plant safety, (2) Unification of similar LCOs and relocating them, (3) Application of any improvements gained from operational experiences and/or research works, (4) Reinforcement of technical bases and also placing greater emphasis on human factor principles in order to make technical specification clearer and easier to understand. The goal of Wolsong CANDU-6 ISTS development is to improve plant safety practically by selecting safety significant LCOs, optimise surveillance requirements and reinforce technical bases, in order that the development of the first one for Pressurized Heavy Water Reactor (PHWR) nuclear power plants could be accomplished in the world. Furthermore, it can be utilized as the standard technical specification to prepare Wolsong-1 Improved Technical Specification (ITS) for the continuing operation after the major refurbishment. Source

Lim C.-K.,Atomic Creative Technology Co. | Chung B.-J.,Kyung Hee University
International Communications in Heat and Mass Transfer | Year: 2014

Experiments on chimney systems were performed using a copper electroplating system based on the analogy concept. Numerical investigations were carried out to examine the influence of an anode placed at the center of a chimney system. The chimney heights were varied for RaD=7.23×109 and Sc=2094. As the chimney height increased, the heat transfer rates were enhanced but the enhancement rate decreased. Comparison of the numerical results with and without the anode showed different velocity and temperature profiles near the anode. However, those near the heated wall exhibited similar values. Thus, the influence of the anode was negligible at a heated wall. This study provides a theoretical background of using an anode to simulate chimney phenomena. © 2014 Elsevier Ltd. Source

Ko B.-J.,Atomic Creative Technology Co. | Chung B.-J.,Jeju National University
Transactions of the Korean Society of Mechanical Engineers, B | Year: 2010

Experiments on laminar mixed convection in a vertical pipe were performed for the Re range 1,000-3,000, the GrH range 105-10 8. the Pr range 2,000-7,000, and aspect ratio range 1-7. Using the analogy concept, heat transfer systems were simulated by mass transfer systems. A cupric acid-copper sulfate electroplating system was adopted as the mass transfer system, and the mass transfer rates were measured. The measured Mi values were far greater than those previously reported because of the large value of Pr in this experiment As the aspect ratio in this study was not sufficiently large for the flow to be fulh/ developed, the test results were similar to those for mixed convection on a vertical plate rather than that inside a long vertical pipe. It was concluded that the behavior of laminar mixed convection of a developing flow in a vertical pipe at a low aspect ratio and low GrH is similar to that of laminar mixed convection in the vertical plate. As the aspect ratio and GrH increase, the laminar nixed convection phenomena becomes similar to mat observed in a fully developed flow in the vertical pipe. Source

Chung D.-H.,Atomic Creative Technology Co. | Kim H.-J.,Atomic Creative Technology Co. | Kim S.-M.,Korea Hydro and Nuclear Power Co.
Canadian Nuclear Society - 32nd Annual Conference of the Canadian Nuclear Society and 35th CNS/Can Student Conference 2011 | Year: 2011

A study has been carried out to gain a picture and some quantitative evaluations of the structural material mesh spacing layout effects of Wolsong CANDU 6 reactors by using the WIMS/DRAGON/RFSP-IST code system. The newly updated code system has been validated to some extents by comparing the Phase-B pre-simulation results of Wolsong Unit 1 against the previously acquired Phase-B commissioning test measurements of Wolsong Units 1,2,3,4. The code validation efforts resulted in the conclusions that the newly adopted code system could be used for the operational support of Wolsong CANDU 6 reactors. As an ongoing striving for the improvement of safe and economic operation of the reactors, a project on BP/CP uncertainty analysis with respect to the WIMS/DRAGON/RFSP-IST code system is planned. The results obtained in the present study strongly suggest that the effects of mesh spacing layouts of structural materials could be used as an important parameter to help grasp a more realistic glance on the overall off-line flux mapping errors that contribute to BP/CP uncertainties. Source

Kim H.-J.,Atomic Creative Technology Co. | Chung D.-H.,Atomic Creative Technology Co. | Kim J.-H.,Atomic Creative Technology Co. | Kim S.-M.,Korea Hydro and Nuclear Power Co.
Canadian Nuclear Society - 32nd Annual Conference of the Canadian Nuclear Society and 35th CNS/Can Student Conference 2011 | Year: 2011

A preliminary study has been conducted to help estimate BP/CP uncertainty of Wolsong CANDU 6 reactors by using the WIMS/DRAGON/RFSP-IST code system. The study is focused on the effects of RFSP-IST core modeling practices, especially, in context of laying out mesh spacings associated with the structural materials in the core. The conceptual approach to figure out the effects of mesh spacing layouts associated with the structural materials is supported by the newly updated code system representing the state-of-the-art CANDU reactor physics theory and methodologies, especially, the DRAGON-IST generated incremental cross sections. The application of RFSP-IST fine mesh core model has been exercised to Wolsong Unit 2 core tracking simulations for about one year period of reactor operations. The results so obtained clearly indicate that the improved validation practices and methodology presented here could be qualified to be incorporated into the entire package of BP/CP uncertainty analysis methodologies in order to enhance the quality and reliability of error estimates related to the various topics, e.g., such as, off-line flux mapping errors. Source

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