AbstractThe four blanket concepts developed within the European Fusion Technology program and supported by the European Community are assessed from the reliability/availability point of view. The reliability of blanket segments influences the availability of the whole plant. In case of a failure, the affected blanket segments must be repaired or exchanged. The mean down time necessary for segments repair or exchange is an important factor for the overall plant availability. It has been assumed to be 3 months for all concepts. To allow a meaningful comparative assessment, an identical evaluation scheme was applied to all concepts using the same basic data. The results show that differences in the availability of blanket concepts are relatively small, with availabilities ranging between 84.3 and 87.7%. The absolute numbers, however, are sensitive to assumptions and to failure modes taken into consideration.