Results of the Preliminary Test in the 1/4-Scale RCCS of the PMR200 VHTR

The Reactor Cavity Cooling System (RCCS) is a key ex-vessel passive safety system that will ensure the safety of the PMR200, and its performance needs to be verified. For the difficulty of the full-scale test, a 1/4-scale RCCS facility, NACEF (Natural Cooling Experimental Facility), has been constructed at KAERI, and a shakedown test has been performed. A brief design and the preliminary test results of this facility are described. A 1/4-scale RCCS mockup of PMR200, NACEF, was constructed and tested preliminarily. The functioning of the facility worked quite well. Moreover, the preliminary test results show a fairly good agreement with past work except for the conductive heat transfer region in the riser bottom. After a remedy such as the installation of more precise flow meters and a more improved insulation, the test facility is likely to work well