Abstract: A steam generator tube repair assembly employs a stud having a shaft and a head which forms a transverse sealing surface. A driver wedge has a central axial bore for receiving the shaft and a generally frustoconical exterior surface for receiving a sealing sleeve. The sealing sleeve has a circumferentially extending sealing surface and an end surface which is adapted for sealing engagement with the sealing surface of the stud head. A coupling nut is tightened to force the driver wedge to swage the sealing sleeve for radial sealing engagement and also transverse sealing engagement. The driver wedge and or the sealing sleeve are formed of shape memory materials so that at a temperature below a transition temperature the diametral dimensions of the sealing sleeve are reduced and at a temperature above the transition temperature the diametral dimensions of the sealing sleeve are expanded into sealing engagement with the tube.

Abstract: An apparatus (10, 110, 210) including a containment capsule (12, 112, 212) a support member (16, 116, 216) removably disposed within the capsule and carrying therein a solid state track recorder material (20, 120, 220) and a layer of fissile material (20, 120, 220), and means (52) on the exterior of the capsule adapted to be remotely grasped for positioning the capsule adjacent to the fuel. The capsule is lowered into close proximity to the fuel, and positioned at a predetermined location for a period of time between about one hour and one day. The capsule is withdrawn from the fuel, the support member and recording member are withdrawn from the capsule, and the recording member is processed to reveal the fission track density, which is readily correlated to fuel burnup.

Abstract: Means for preventing chip penetration of fractured ceramic fuel into the cladding of a fast spectrum nuclear reactor fuel element is disclosed. Included in the fuel element external to the pellet column but internal of the cladding is a woven cylinder or web of fine wire or of bandage wrapped metallic ribbons. The cylindrical web acts to retain ceramic chips in their positions so that they do not become lodged between the pellets and the clad: which condition could lead to clad failure.

Abstract: A fuel-pellet composition for use in fast breeder reactors. Uranium carbide particles are mixed with a powder of uranium-plutonium carbides having a stable microstructure. The resulting mixture is formed into fuel pellets. The pellets thus produced exhibit a relatively low propensity to swell while maintaining a high density.

Abstract: A nuclear fuel pin is formed of an elongated metallic tube, closed at each end, containing stacked fuel pellets and material including little, or no, fissionable material, and formed into porous, or bubbled, microspheres placed in the annulus between the pellets and the internal wall of the tube.