Irradiation Testing of Enrico Fermi Prototype Fuel Pins in the CP-5, 1957-1959

A program was conducted to proof-test zirconium-clad molybdenum-uranium alloy fuel pins and to verify the predicted allowable burnup of this alloy based on previous MTR capsule irradiation tests. Tests of three full-length pins were completed with burnups ranging from 0.3 to 1.0 at.%. These results verified predicted high-temperature allowable burnups and showed that under certain conditions excessive swelling could occur at low temperatures. Test procedures are described, and photographs showing microstructures are included along with various experimental data. (J.R.D.)