[3K04-07] Evaluation Technology and Plant Safety Assessment

[3K07] AP1000^® safety assessment for beyond design basis events

(3)Containment Integrity

*Yukitaka Yamazaki¹, James H Scobel², Richard F Wright² (1. Westinghouse Electric Japan Ltd., 2. Westinghouse Electric Company)

Keywords:Pressurized water reactor, Passive safety system, AP1000, Beyond design basis event

The AP1000 plant is the pressurized water reactor adopting the passive safety concept. The containment integrity is preserved by the passive containment cooling system (PCS) which establishes 72-hour containment heat removal with a PCS tank of water located on top of the shield building. Onsite resources are provided to sustain the containment heat removal for an additional 4 days, out to 7 days, with minimal operator actions and power requirements. The containment integrity was assessed for a very unlikely event that makeup water is not provided to the containment cooling surface after depletion of the gravity-drained water from the PCS water storage tank and onsite additional 4-day resources due to combination of independent failures.