Primary side safety systems. Essentially all primary side safety systems are shown in this figure, the only exceptions being: isolation valves in non-safety grade systems, hydrogen igniters/recombiners, and various instrumentation and surveillance equipment. The items indicated in the figure are: CB, containment boundary; FCV, filtered containment vent; SFP, spent fuel pool; CFT, cavity flooding tank; SB, safety boration tanks; EVHX, ex-vessel heat exchanger; FT, flooding tanks; DSV, depressurization system valves; OPV, overpressure protection valves.