Outside the pool itself, you may find three independent pump-assisted coolant circulation systems. Each of these three is enough in itself to remove 50% of the core heat at full power. Thus, with two of these circuits active in normal operations, the third becomes a back-up. 

The primary cooling system dissipates the fission heat by means of light water, in forced upwards circulation.

The design guarantees the thermal stability of the cooling water intake within close limits, regardless of the external temperature due to weather conditions.

Outside the pool, the primary cooling system divides in three circuits. Each of these has a pump and a heat exchanger apt to handle 50% of the reactor power. Thus, one of the circuits becomes a redundant backup system.

Each of the cooling systems serving the reactor pool and the auxiliary pool has the following functions:

• Dissipation of the heat from the irradiation facility, during normal operation, by forced upwards circulation of light water.
• Dissipation of the core decayment heat and continuous cooling of the irradiation facilities when the reactor is shutdown, by natural circulation.
• Keeping the pool water temperature within the prescribed range, for all foreseeable operating conditions.
• Dissipation of the heat generated by spent fuel elements.

The neutron reflector surrounding the core has its own indepen- dent heavy water circulation, cooling and purification system.  The secondary cooling system extracts heat from the primary cooling circuit, from both reactor and auxiliary pool cooling systems, from the neutron reflector cooling system and from other thermal sources within the reactor. All this heat is finally dissipated to the environment by means of the cooling towers.
		Cooling water stays within strict purity standards thanks to mixed ion-exchange resin beds. Neutron mirror heavy water operational quality standards are maintained by similar means, through their own circulation and purification system.

The purification and distribution system ensures that the cooling water stays within stringent purity standards. To achieve this, mixed ion exchange resin beds are the choice. A warm top water layer is established and kept by means of yet another circulation and purification system, to reduce the radiation dose rate on the surface of the pool.

Heavy water quality is kept within safe operational standards by means of another mixed ion exchange resin bed. The deuterium and oxygen concentrations are kept constant by recombination.

All the pipes connecting to the reactor pool are above the core level. Syphon-breaking mechanisms are provided to prevent the emptying of the pool by syphoning.

The primary circuit and that of the reactor pool have butterfly valves to allow natural circulation.