The Fast Breeder The possibility of breeding in a fast reactor has been adequately nically operable for producing power and which will still breed. For success, the Fast Breeder must operate at a very high power density, e.g., 1000 KW of heat per liter of total core volume. The effect of "diluting" the core with other materials for the heat extraction function is critical on the neutron spectrum and on breeding performance, and is as yet very uncertain. The present program is concentrating on a second Experimental Breeder Reactor (EBR~II), to be built at Arco at a cost of about $19 million, It will be primarily a test of engineering components to demonstrate technical feasibility as a power producer, Since feasibility must involve recycling of fuel,it will be an integrated plant, with refabrication of fuel elements ce eee ee ee —s saeneo Se by remote control. The heat production will be some 60 megawatts and electric power will be generated. Current thinking on fuel element design envisages cylindrical pins which are centrifugally cast and only 0.164" in diameter, in long tubes of 0,188" OD, with sodium bonding in the annulus and sodium cooling outside the tubes. An alternate design uses thin perforated wafers, prepared by powder metallurgy, which are held together with tubes pushed through the perforations in the uranium wafer matrix. Sodium coolant flows through the tubes. In either case the mid-section of the length will contain active material and the ends will contain depleted uranium blanket material. Xp . at “ ‘ The question now is whether a fast reactor can be designed and built which will be tech- A eeelhnRN hint ob Bat ow sot demonstrated in the first Experimental Breeder Reactor (EBR-I). oe Oe oA ARS 5 ‘ oF