Performance of (U,Zr)C-graphite (composite) and of (U,Zr)C (carbide) fuel elements in the Nuclear Furnace 1 test reactor

The properties of and reactor test results for two types of nuclear- propulsion-reactor fuel elements containing uraniumzirconium carbide, (U,Zr)C, are reported. Composite fuel elements containing graphite and ~35 vol% carbide, along with fuel elements consisting only of carbide, were tested in Los Alamos Scientific Laboratory's Nuclear Furnace 1 reactor for l09 min at peak power densities of ~4500 MW/m/sup 3/ and temperature up to 2500 deg K. Fission-fragment damage to the graphite phase of the composite fuel elements increased the roomtemperature thermal resistivity of the matrix ninefold, resulting in unexpected high mass losses of carbon. The carbide elements developed both longitudinal and transverse fractures but did not fragment into small-size particles. (auth)