Performance Improvement of VHTR Key Technologies

The purpose of this research project is to improved VHTR key technologies for development and demonstration of VHTR (Very High Temperature Reactor) for multiple-use of nuclear energy in the event of future demand. The following R&D has performed to achieve the goal. VHTR design analysis codes have improved by adding transient analysis capability and others improvement with verification and validation that the codes system can be used for the VHTR design. Reactor operational performance analysis module was adding in the system and safety analysis code, GAMMA+. Fission product transport analysis codes were developed and basic validation has succeeded. Experimental data were obtained by using domestic facilities for validation of core thermo-fluid analysis, fission product transport analysis, and safety analysis codes. A design and analysis procedure for intermediate heat exchanger of a PCHE (printed-circuit heat exchanger) type was developed. A diffusion bonding condition of high temperature material (Alloy 617) with world-class structural strength was obtained. The material tests were carried out. Thermal and mechanical tests for oxidized nuclear graphite and mechanical tests for nuclear graphite at high temperature were conducted. Thermal aging tests for Alloy 617 weldment and creep tests for the thermally aged specimens and creep and low cycle fatigue tests for Alloy 800H weldment were also performed. The obtained data have contributed to GIF material DB to maintain the DB license. Development and optimization of ZrC/SiC multilayer coatings process were carried to improve the fuel performance in high temperature and irradiation conditions. Investigation of new technology for heat utilization of VHTR, reactor/interface system performance analysis, and economic analysis were carried out to enhance the multi-purpose utilization