Recent experiments have extended the mechanical properties data base of 20 percent cold worked 316 stainless steel to a fluence of 1.3 x 10/sup 23/ n/cm/sup 2/ (E > 0.1 MeV), the goal exposure of the Fast Flux Test Facility. Both uniaxial and biaxial tests were conducted on speciments of developmental cladding which were irradiated in the Experimental Breeder Reactor-II at temperatures ranging from 370/sup 0/C to 650/sup 0/C. Uniaxial tensile tests were conducted at strain rates ranging from 10/sup -5//s to 10/sup -//sub 3//s. Controlled Biaxial Strain Rate (CBSR) tests, recently developed at the Hanford Engineering Development Laboratory, were conducted only at a strain rate of 10/sup -5//s. CBSR specimens are gas-loaded to produce a constant diametral strain rate. These tests are otherwise analogous to uniaxial tensile tests. The tensile strength and ductility of the cladding were generally in good agreement with the predicted values.