[en] The tensile properties of welds of base metals ASTM A533, Grade B, Class 1 steel plate and ASTM A508, Class 1 forgings were evaluated in irradiated (3 to 21 x 10¹⁸ n/cm²) and unirradiated conditions. Yield strength and ultimate strength both increased with increasing fluence, while small ductility losses were generally independent of fluence. Yield strength was found to be more sensitive to irradiation than ultimate strength for all welds. The strength and ductility responses to irradiation varied between the weld materials. These variations were attributed to differences in chemical constituents of the welds