S>Nickel was used as a diffusion barrier for Al-clad uranium alloy fuel elements, operating at 650 nif- F in organiccooled reactors. Advanced organic-moderated reactor (AOMR) concepts include operating temperatures up to 850 nif- F. Since the interdiffusion of Al --Ni is 150 times faster at 850 nif- F than at 650 nif- F, an alternate diffusion barrier is required. Subsequent studies resuited in the selection of niobium. Several techniques for bonding niobium to the U--10 Mo fuel were investigated. After considerable development effort, electron beam vacuum deposition yielded adherent, nonporous, ductile coatings. Isostatic bonding, at 1050 nif- C and 12,000 psi for 1 hr, also resulted in metallurgically bonded niobium on the major surfaces of U-10 Mo fuel plates. Roll-bonding achieved metallurgically bonded plates on small test specimens, but was never reproduced on full-size plates. Vapor phase deposition, by H2 reduction of NbCl5, was also partially successful, but not reproducible. Ultrasonic bonding has shown promise in spot welding tests. Plasma-spray coating and electroplating in a fused salt bath were also considered, but not actively evaluated. (auth).

NSA is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, pre-dating the prestigious INIS database, which began in 1970. NSA existed as a printed product (Volumes 1-33) initially, created by DOE's predecessor, the U.S. Atomic Energy Commission (AEC). NSA includes citations to scientific and technical reports from the AEC, the U.S. Energy Research and Development Administration and its contractors, plus other agencies and international organizations, universities, and industrial and research organizations. References to books, conference proceedings, papers, patents, dissertations, engineering drawings, and journal articles from worldwide sources are also included. Abstracts and full text are provided if available.