In order to study the potential swelling behavior of the ODS ferritic alloy MA957 at very high dpa levels, specimens were prepared from pressurized tubes that were unirradiated archives of tubes previously irradiated in FFTF to doses as high as 110dpa. These unirradiated specimens were irradiated with 1.8MeV Cr+ ions to doses ranging from 100 to 500dpa and examined by transmission electron microscopy. No co-injection of helium or hydrogen was employed. It was shown that compared to several tempered ferritic/martensitic steels irradiated in the same facility, these tubes were rather resistant to void swelling, reaching a maximum value of only 4.5% at 500dpa and 450°C. In this fine-grained material, the distribution of swelling was strongly influenced by the presence of void denuded zones along the grain boundaries.