The cause of the reactor disaster at Fukushima was insufficient heat transfer from the fuel pool

=>All nuclear reactors worldwide have to ensure a safe heat transfer from the fuel pool in an emergency

Solution:  Passiv-active
fuel pool cooler
 
Principle: 

Cooling water at the Primary-side (i.e. from firefighter) drives a turbopump which in turn sucks the warm fuel pool water and pumps it through a plate heat exchanger

Advantages of this design using the example of a 1MW cooler

Einhaengekuehler detail_kuehler
Property Advantage
Extremely high K-value > 6000W/m²K
(with free convection max. 400W/m²K)
Dimensions of the cooler including turbo pump (LxWxH): 600mm x 400mm x 600mm
Mass of the cooler: 100kg
Mass of the turbopump 50kg
Mounting/Support Suspension in the fuel pool directly with the DN80 primary-side medium pipes
Hot water suction Suction of the warm fuel pool water directly below the water level (hottest water)
Outlet Blown out of cooled fuel pool water by a jet nozzle directly into the fuel pool → direct cooling