[en] These works focus on the development of attainment indices for nuclear hydrogen key technologies, the analysis of the hydrogen production process and the performance estimation for hydrogen production system, and the assessment of the nuclear hydrogen production economy. To estimate the attainments of the key technologies in progress with the performance goals of GIF, itemized are the attainment indices based on SRP published in VHTR R and D steering committee of Gen-IV. For assessing the degree of attainments in comparison with the final goals of VHTR technologies in progress of researches, subdivided are the prerequisite items conformed to the NHDD concepts established in a preconceptual design in 2005. The codes for analyzing the hydrogen production economy are developed for calculating the unit production cost of nuclear hydrogen. We developed basic R and D quality management methodology to meet design technology of VHTR's needs. By putting it in practice, we derived some problems and solutions. We distributed R and D QAP and Q and D QAM to each teams and these are in operation. Computer simulations are performed for estimating the thermal efficiency for the electrodialysis component likely to adapting as one of the hydrogen production system in Korea and EED-SI process known as the key components of the hydrogen production systems. Using the commercial codes, the process diagrams and the spread-sheets were produced for the Bunsen reaction process, Sulphuric Acid dissolution process and HI dissolution process, respectively, which are the key components composing of the SI process

[en] The major objective of this work is tow-fold: one is to develop a methodology to determine the best VHTR types for the nuclear hydrogen demonstration project and the other is to evaluate the various hydrogen production methods in terms of the technical feasibility and the effectiveness for the optimization of the nuclear hydrogen system. Both top-tier requirements and design requirements have been defined for the nuclear hydrogen system. For the determination of the VHTR type, a comparative study on the reference reactors, PBR and PBR, was conducted. Based on the analytic hierarchy process (AHP) method, a systematic methodology has been developed to compare the two VHTR types. Another scheme to determine the minimum reactor power was developed as well. Regarding the hydrogen production methods, comparison indices were defined and they were applied to the IS (Iodine-Sulfur) scheme, Westinghouse process, and the, high-temperature electrolysis method. For the HTE, IS, and MMI cycle, the thermal efficiency of hydrogen production were systematically evaluated. For the IS cycle, an overall process was identified and the functionality of some key components was identified. The economy of the nuclear hydrogen was evaluated, relative to various primary energy including natural gas coal, grid-electricity, and renewable. For the international collaborations, two joint research centers were established: NH-JRC between Korea and China and NH-JDC between Korea and US. Currently, several joint researches are underway through the research centers

[en] To improve the prediction capability of safety analysis code for the phenomena occurring in the advanced safety system of new nuclear plant, the local physical model should be developed based on the fine scale of experimental data for the key phenomena. The current study performed high-precision experiment and constructed database for key phenomena for the boiling induced natural convection inside cooling tank and tube inside condensation of heat exchanger of passive auxiliary feedwater injection system, dynamic multi-dimensional behaviour of ECC water inside downcomer from DVI system. To achieve local high-precision experimental data, measuring technique was newly developed or improve the applicability of the conventional instrument such as optical probe, laser optics including PIV, LDV and LIF, and ultrasonic measuring techniques. Based on the force or energy balance, mechanistic physical models were uniquely developed for the bubble departure diameter on curved heated surface, condensation heat transfer inside heat exchanger tube and interfacial shear on the liquid film. The boiling phenomena is very important for the heat transfer and thermal margin evaluation of reactor safety. experiment for high heat flux condition was performed using high resolution of visualization. From the visualization, the boiling structure and mechanism near CHF condition was analyzed. As one of the key boiling parameter, a bubble departure size model was newly developed based on balance equation of heat transfer. The experimental database and unique mechanistic physical models developed in this study, will enhance the brand value and the accuracy of the prediction capability of the domestic safety analysis code, which will contribute to the nuclear plant export.