Fabrication Experience of AI-²³³U and Al-Pu Plate Fuel for the Purnima III and Kamini Research Reactors

Aluminum-clad Al-20 wt% ²³³ U and Al-23 wt% Pu plate fuel subassemblies have been fabricated for the Purnima III critical facility and the Kamini research reactor. The fabrication flow sheet consists of preparing the master alloy using aluminum and uranium or plutonium metals as feed materials, remelting and casting the fuel alloy ingots, rolling, picture framing and sandwiching the fuel alloy between aluminum sheets, roll bonding, locating the fuel alloy core outline by X-ray radiography, and trimming and machining to final dimensions. Metallic molds produce better ingots than graphite ones. The addition of zirconium during melting improves the microstructure of the Al-U and Al-Pu castings and facilitates hot rolling of the ingots. In the subassembly the fuel plates are finally locked in aluminum spacer grooves by a novel roll-swaging technique. High-resolution X-ray radiographs and microdensitometric scans are utilized to confirm the homogeneous distribution of the fissile material in the fuel plates. Nonbond areas are detected by blister testing and immersion ultrasonic testing of the roll-bonded fuel plates.