Predicted performance of the ferritic/martensitic alloy HT9 cladding in an FFTF test of advanced oxide fuel

The successful utilization of ferritic/martensitic alloy HT9 in an FFTF test assembly is fully anticipated. The planned period of irradiations 1000 days. The low swelling observed at intermediate neutron fluences and projected to higher fluences together with reasonable creep behavior imparts acceptable mechanical performance for fuel pins and duct. Duct length increase, dilation and bow; plus fuel pin diameter increases remain within specified tolerances. In addition stress rupture data, from unirradiated HT9 imply cumulative damage fractions for the nominal fuel pin that are low.