Analysis of Primary Containment Capture System for the propose Advanced Modern 600 nuclear power plant

Analysis of global electric markets shows that the electrical grid size of many developing countries is too small or too distributed to accommodate nuclear power plants (NPP) with large unit sizes. Thus a modern NPP design with a smaller output (∼600 MWe) as well as with proper confidence of public safety is of interest. But as the Fukushima Daiichi NPP accident demonstrates, natural disasters can severely challenge the existing safety philosophy of defense in depth at NPPs. To improve and reinforce defense in depth, a new barrier to fission product release, a long-term and passive system against environmental release - a Primary Containment Capture System (PCCS) for Advanced Modern 600 MW (AM600) is proposed. This system is designed to confine ex-containment release and to prevent containment failure from overpressure. In this study the thermal-hydraulics behavior of the PCCS of different length is studied. Analysis results show that a 1-km length with 8 m diameter gravel filled tunnel (PCCS) can maintain safe conditions for containment for 10 days following extended Station Blackout (SBO), and consequently the higher length for longer period without any release to the environment. The concept of the tunnel that is connected with containment will be suitable for multiunit site.