Among the design basis conditions, the main accidental transients (blackout, steam line rupture, steam generator tube rupture, and LOCA) were studied with the CATHARE code. All calculations were performed with 4 out of 16 available RRP loops. These four RRPs are automatically actuated with the shutdown signal. In case of failure of the actuation, a control system will actuate other RRP loops.

Blackout

For this transient, the power is firstly removed by the SG and later by the RRP system. The RRP system reaches its full operation at about one thousand seconds. After one hour and half, the removed power by RRP is enough to cool the reactor.

Cold shock

In case of steam line rupture, the magnitude of cold shock is 22°C at core inlet. The number of the control rods is sufficient to stop the reactivity increase until the cold shut down. After the trip, the residual power is firstly removed by the released steam of the SG, and secondly it is stored in the large thermal inertia of the primary circuit. The RRP loops reach their full power in one thousand seconds. One hour after the beginning of the transient, the RRP remove all residual power. In this transient there’s no released water at the safety valve of the pressurizer.