Fabrication of ceramic fuel pellets for isotopic heat sources

A production process was developed to fabricate cylindrical pellets for the GPHS. The process consists of hot-pressing a blended mixture of sintered /sup 238/PuO/sub 2/ granules prepared from calcined plutonium oxalate powder. The product is a pellet of nominally 84.5% total density which generates 62.5 watts (thermal). Hot pressing and granule sintering conditions require close control to minimize surface and internal cracking and to permit ejection of the pellet from the hot press die. Uniform density and distribution of large intergranule porosity in the microstructure appear to contribute to the dimensional stability required at elevated temperatures and the mechanical ruggedness required for routine handling during production operations.