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: 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.