Integral nuclear fuel element assembly

In a heavy water-moderated plutonium-uranium breeder reactor a low moderator-fuel ratio is desirable in order to increase the breeding ratio; however, fuel element spacing must be carefully controlled to provide good moderator flow and prevent the formation of hot spots on the fuel element surfaces. A fuel assembly made in accordance with this invention utilizes longitudinally-finned fuel pin cladding tubes arranged to form an integral fuel assembly by brazing together the continuous or interrupted fins of one fuel pin to the fins of other fuel pins. Alternatively, the fins of some fuel pins may be connected directly to the tubular section of other fuel pins. In another embodiment of this invention, the core is fabricated from a solid material having passages suited for coolant flow and fuel retention