SEALER (Swedish Advanced Lead Reactor) is a passively safe lead-cooled reactor designed for commercial power production in a highly compact format. Its fuel is never replaced during operation, which minimises costs related to fuel management. The integrity of steel surfaces exposed to liquid lead is ensured by use of alumina forming alloys.

Safety
Passive safety of the reactor is ensured by removal of decay heat from the core by natural convection of the lead coolant. Transport of the residual heat from the primary system is accomplished by activation of dip-coolers that will keep the system temperatures within the normal operating range. If the dip-coolers are not activated as intended, the coolant temperature increases so that residual heat can be transported by radiation from the primary vessel to a guard vessel, which is cooled by natural convection of air. In the event of a core disruptive accident, volatile fission products are retained in the lead coolant and no evacuation of persons residing at the site boundary will be required.