Method for removing cesium from a nuclear reactor coolant

A method for removing cesium from a liquid metal circulating through a primary cooling system of a nuclear reactor is described which consists of: providing a primary carbon packing trap in the primary system, continually absorbing cesium from the coolant onto the carbon packing trap at a relatively low temperature until the trap is substantially saturated with cesium, isolating the primary trap when saturated from the primary system by disconnecting the trap therefrom and connecting the primary trap to a closed regeneration flow system having a secondary carbon packing trap. The closed regeneration flow system is completely isolated from the primary coolant system and having a volume substantially smaller than the primary coolant system, increasing the temperature of the coolant passing through the primary trap, diffusing a portion of the cesium inventory on the surface of the primary trap further into the matrix thereof while dispersing a portion of the cesium inventory into the coolant circulating through the regeneration flow system, reducing the temperature of the coolant passing through the secondary trap, and physically and chemically absorbing cesium from the coolant in the regeneration flow system onto the secondary carbon packing trap until cesium equilibrium between the traps is reached whereby the primary trap is reconditioned for further usage when reconnected to the primary system