One of strategies for developing fusion reactor materials is to start from clear understandings of microstructural evolutions and of their mechanisms.The pure and model alloys group in FFTF/MOTA program cares for elementary and basic processes of radiation damage mainly from damage microstructural development.This paper provides recent results from MOTA program on austenitic steels.The importance of radiation induced segregation and radiation enhanced precipitation in microstructural evolution and phase stability is emphasized.