The SP-100 Space Nuclear Reactor design required a rhenium barrier between the uranium nitride nuclear fuel and the niobium alloy cladding. For higher strength and thermal performance, it was deemed desirable to metallurgically bond the rhenium barrier tube to the Nb-1%Zr cladding tube. The bonding was achieved by brazing both ends of the rhenium and Nb-1%Zr tubes, in a vacuum, with a special braze adapter, and then hot isostatically pressing (HIP) the brazed assembly. A considerable amount of effort went into developing the brazing process and the two stage HIP cycle for the bonding. A brazing adapter and electron beam heating process were developed to melt the vanadium braze in place. A relatively low pressure was chosen in the first stage HIPing cycle to assure that the weaker Nb-1%Zr tube collapsed uniformly onto the rhenium tube without any deformation in the stronger rhenium tube. Avoidance of deformation in the rhenium tube was necessary because rhenium has low ductility at the HIPing temperature of 1350 degree C. In the second stage, the temperature and pressure were increased to assure metallurgical bonding of the rhenium and Nb-1%Zr tubes.
Development of bonded rhenium/niobium-1%zirconium tubing for the SP100 space nuclear reactor
1997
13 Seiten, 4 Quellen
Conference paper
English
Fabrication of tungsten and tungsten-25 rhenium tubing.
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