Sodium cooled fast reactor secondary loop is also called the intermediate circuit.It is design for insulating the radioactive sodium in the primary loop from water vapor loop,at the same time assuring the thermal energy transfer from the primary loop to the non-radioactive sodium circulation system settings for the water vapor Sodium cooled fast reactor secondary loop is also called the intermediate circuit. It is designed for insulating the radioactive sodium in the primary loop from water vapor loop, at the same time assuring the thermal energy transfer from the primary loop to the non-radioactive sodium circulation system settings for the water vapor