Design of APR1400 NSSS major components

To achieve improvements in safety and economical efficiency, Korea Hydro Nuclear Power Company (KHNP), with support from industries and research institutes, developed the Advanced Power Reactor 1400 (APR1400). Major improvements include: -) concerning the pressure vessel: the adoption of DVI nozzles inside the reactor vessel, and the adoption of the integrated assembly for the reactor vessel head area; -) concerning the steam generator: an increase in the tube plugging margin (+2% compared to the OPR1000 design) and the optimization of the upper tube bundle system to minimize the tube thinning caused by secondary flow between tubes and their supports; -) concerning the pressurizer: the replacement of the 3 pressurizer safety valves and 2 safety depressurization system valves by 4 pilot operated safety relief valves; -) concerning reactor vessel internals: the optimization of their design by using the CEP (Collaborative Engineering Process); and -) the installation of the fluidic device in each safety injection tank in order to control the discharge rate of water. The manufacturing of the components for the Shin-Kori units 3 and 4 has begun as the first APR1400 units to be built