Power conversion systems utilizing two-phase flows have been used and are being considered for use in the microgravity acceleration environment of outer space (e.g., a nuclear-powered organic Rankine cycle for a follow-on space station). Reactor accident and safety analysis codes exist for terrestrial applications; however, fundamental assumptions inherent in these tools will be violated in space applications. A major effect of the microgravity environment is the lack of an acceleration body force acting on the fluid phases. Without such a body force, fluid phases do not naturally separate nor do natural convection flows develop, and conventional condensation and boiling models do not apply. Therefore, the reactor design and safety analysis codes developed for terrestrial use are inappropriate for space applications. Recognizing this, the National Aeronautics and Space Administration (NASA) has funded a project at Texas A and M University whose purpose is to design and fly microgravity two-phase flow experiments, developing phenomenological models appropriate to the space environment. This summary describes the work carried out to date and discusses its potential impact on reactor safety.