Fast breeders

Purpose: To prevent the transfer of tritium discharged into a primary sodium coolant into a secondary cooling system upon production of the tritium in a reactor core. Constitution: A heat transfer tube of an intermediate heat exchanger for transferring the heat of a primary sodium cooling system into a secondary sodium cooling system is formed in a double-walled tube, and means for removing tritium in helium gas is provided partly at the helium gas circulation loop having the gap of the tube as a helium gas flow passage. In this manner, it can substantially completely prevent the tritium discharged into the primary sodium coolant from moving into the secondary system, therby facilitating the prevention of the tritium from discharging into the environment. Since no radioactive nuclide contamination occurs, the maintenance, inspection and repair works of the equipments in the secondary system can be extremely readily performed. (Yoshihara, H.)