In the CAREM modules using natural convection in the primary coolant system (CAREM designs with a unit power of less than 150 MW(e)), there are no primary pumps, thus this initiating event is excluded. In higher power modules with forced circulation, natural convection is enhanced intrinsically by the integral type layout of the primary circuit.

Loss of coolant

The diameter of RPV penetrations is limited by design (there are no large diameter penetrations). Therefore, no large LOCA is possible and there is no need for a high pressure injection system. In case of a LOCA, the FSS, SSS, and RHRS are actuated and, when the pressure is decreased, the emergency injection system discharges water to keep the core covered for several days. As the CAREM design obviates active systems, in safety evaluations the secondary coolant system is not assumed to cool and depressurize the primary system. However, once it is available and when needed, it could be used as part of the accident management strategy.

The inherent response of the reactor to LOCA has been analyzed considering a FSS success and the failure of all safety systems related to core cooling. Due to a large water inventory over the core and small diameters of RPV penetrations, the core is uncovered only after several hours.