Strategies for Applying Retrofit Radiation Shielding to the ISS 2001-01-2369

Currently, the exposure limits outlined for crews of the ISS (International Space Station) are based on two principles. The first is that the excess risk to that crewmember be maintained at a level below 3%. The second is that radiation protection personnel must adhere to the ALARA (As Low As Reasonable Achievable) principle. This principle would mandate that for any exposure, the risk incurred as a result be weighed against the social and economic benefits of the activity. An ancillary conclusion of this principle is that if it is possible to lower an exposure through relatively low cost, while not hindering the benefits, then that type of precaution should be pursued. With this in mind, the Space and Life Science Directorate at NASA’s center for manned spaceflight, Johnson Space Center in Houston, has undertaken a project to retrofit radiation shielding into those portions of the ISS where crews are expected to spend larger amounts of time. We present here an overview of the strategies, constraints, and preliminary results of this analysis. In addition, we present an overview of the suite of calculational tools used, their status, and work in progress to update the design environment in which analyses of this type are performed in support of manned spaceflight.