| Popis: |
subscale fiat-plate fuel subassemblies measuring up to 2 by 2 by 20 in., incorporating 16 Zircaloy-2-clad uranium -zirconium fuel plates and 15 coolant channels, were successfully fabricated by the gas-pressurebonding process. Autoclave design, specimen-container configuration, and the design and preparation of specimen components were among the problems studied. Uneven heating of the bonding specimen, caused in part by convective heat transfer, was minimized by developing a special four-element muffie-type resistance heater for the autoclave and by filling void space between the specimen and heater with copper plates and sand. With this arrangement there was only a 10 to 15 deg F variation over a 36-in. zone at 1500 deg F. A type 304 stainless specimen container design, resembling in cross section a swastika, allowed distortion-free bonding of specimens without supplementary jigging. The practicality of building up an entire assembly from simple, rectanrular pieces was demonstrated. This technique makcs it easier to maintain the close dimensional tolerances required for fabrication of flat-plate assemblies and elimirates the expensive machining required to produce one-piece picture frames. Flat Ti-Namel stock inserted between the Zircaloy-2clad fuel plates during assembly of the components was removed after bonding was completed by acid etching to form the coolantmore » channels. Chromium plating the Ti Namel prevented reaction with the Zircaloy-2. In studies of surface preparation, it was found that removing 2 to 3 mils of surface by reaching belt abrading of the components with 60-grit SiC produced consistent bonding. Bonding of the assemblies at 1550 deg F for 4 hr under a helium pressure of 10,000 psi produced excellent results. (auth)« less |
