Irradiation creep of vanadium-base alloys

A study of irradiation creep in vanadium-base alloys in underway with experiments in the advanced test reactor (ATR) and the high flux isotope reactor (HFIR) in US. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200-300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from ∼0 to 1.2 x 10-5/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence. (orig.)