[en] A review is presented of the early results of several related studies designed to explore in simple Fe-Cr-Ni alloys the influence of helium/dpa ratio in competition with other important material and environmental variables at 330--600 degree C. While helium at fusion-relevant levels influences the details of the microstructure somewhat, the resultant changes in macroscopic properties such as swelling and tensile behavior are relatively small. However, when greater-than-fusion levels of helium are generated, an extensive refinement of microstructure occurs, leading to depression of swelling at lower temperatures and increased strengthening at all temperatures studied. 23 refs., 10 figs