For accident response, the PCCS provides long-term passive cooling capability fo r the containment using natural convection processes.
Decay heat is rejected to isolation condenser pool and then to the atmosphere.
No active pumps or diesels ate needed for the heat removal, resulting in no operator action requires for a t least three days. Beyond three days, water makeup and other simple operator action are all that i s needed to continue passive cooling. Fission pproducts are retained in the supression pool and multiple barriers contain fission produscts inside the plant. There is no containment flooding for most LOCAs. SBWR response to low-elevation LOCAs and severe accidents provides for lower drywell flooding.