The integrated primary system concept eliminates all large primary circuit pipe work, thus intrinsically eliminates large loss of coolant accidents. The largest pipe break in the primary circuit is the break of the connection pipe supplying chemical and volume control system(CVCS). To prevent siphoning off the reactor wrater inventory in the hypothetical event of a CVCS line break, open connections are made between the steam generators and pressurizer. Thus there is no possibility of rapid emptying of the reactor vessel requiring massive and early injection of ECCS water. Since reactor vessel is flooded all the time by the water in the safe guard vessel, there is no need for external emergency core make up. The safe guard vessel is sized to provide a minimum of 72 hours’ heat removal without operator intervention.

2.3.3 Containment Overpressure Protection System

Since the maximum pipe break is small due to the integral nature, the pressurization rate of containment is slow. Energy released to the containment through the break point is removed using the steam injector driven containment spray system to prevent exceeding the containment design pressure. The steam injector is a simple, compact passive pump that is driven by supersonic steam jet condensation. The steam injector can operate even by atmospheric pressure steam. The steam from break point is supplied to the steam injector. The steam injector pumps up the water from a water storage tank on the ground to the spray nozzle located at the top of the containment.