Risk and uncertainty can destabilise and reconstruct the relationships between medicine, policy and publics. Through semi-structured interviews with medical staff following the Fukushima 3.11 Disaster, this paper demonstrates the way in which disruption (caused by disaster), coupled with uncertainty (in this case, around radiation risk) can serve to transform medical practices. After Fukushima, a deficit in publicly-trusted approaches to disaster management meant that the role and status of key medical professionals was transformed. This reorganisation of medical work included the development of new forms of expertise, the stretching of expertise beyond previously well-defined professional boundaries, and shifts in the way in which medical professionals understand and interact with publics. These changes signified the rise of new relationships between the medical workers and their community, as well as adjustments in what were regarded as the boundaries of medical work. Given both the ubiquitous threat of disasters and calls for increased engagement between the medicine and the public, this case study provides insight into the forms which such engagements can take, especially when bound by conditions of uncertainty. The paper draws upon the theoretical literature around the impact of uncertainty on policy, and combines this with medical sociological literature on the nature of medical expertise. The paper examines the shifting of medical expertise towards mode 2 forms, and evidences the impact of a democratised science of risk on the roles and functions of medical practice.