The influence of radiation on the properties of welds and joints

The effect of radiation on mechanical properties of candidate structural materials for the first wall and breeder blanket of fusion reactors is reviewed. The emphasis is placed on austenitic stainless steel type 316L and its weld metals; design parameters considered are similar to those currently specified for the Next European Torus, namely, irradiation doses ≤ 15 dpa, temperatures ≤ 4000C, number of pulse cycles ≅ 105 and hold times ≤ 15 mn. The effect of irradiation on other materials, including austenitic stainless steel Type 304L, weld metal Type 308L and ferritic/martensitic steels (9-12% Cr-Mo), as well as other service conditions such as temperatures as high as 5500C are also briefly discussed. The data collected and presented in this review are those usually measured before and after irradiation, through tensile, impact toughness, fracture toughness, fatigue, creep-fatigue and fatigue crack propagation testing. In each case the influence of irradiation parameters on the observed changes are discussed and relative conclusions are drawn. The most important observation made is the lack of medium dose irradiation data on the weld metal and in particular on the electron beam welded joints. (orig.)