The inherent safety features of CAREM are:

• Integrated primary coolant system, eliminating large break LOCA;

• Long characteristic times in the event of a transient or severe accident, due to large coolant inventory and the use of passive safety systems;

• Natural convection core cooling in lower power modules (e. g., CAREM-25) eliminates loss of flow accidents (LOFA);

• Hydraulic control rod drive mechanisms located completely inside the RPV eliminate control rod ejection accidents;

• Negative reactivity effects and coefficients, see Table III-2.

Passive safety systems

The CAREM safety systems are based on passive features obviating the need for accident management over a long period [III-1, III-2]; see Fig. III-2. Systems are duplicated to fulfil redundancy criteria. According to Argentine regulations, the shutdown system is diversified.

Natural circulation and self-pressurization properties

Flow rate in the reactor’s primary systems is achieved by natural circulation. The driving forces resulting from differences in density along the circuit are balanced by friction and shape change losses, producing an adequate flow rate in the core and securing a sufficient thermal margin to critical phenomena. Natural convection of reactor coolant is due to the location of the steam generators above the reactor core.

Self-pressurization of the primary system in the steam dome results from liquid-vapour equilibrium. The large volume of the integral pressurizer also contributes to damping of eventual pressure perturbations. Heaters and sprinkles typical of conventional pressurized water reactors (PWRs) are, therefore, eliminated.

Eliminating primary pumps and the pressurizer results in added inherent safety features (loss of flow accident elimination), and in advantages for maintenance and availability.