[en] Quantitative risk assessment (QRA) principles provide an effective framework for quantifying individual elements of risk, including the risk to astronauts and spacecraft of the radiation environment of space flight. The concept of QRA is based on a structured set of scenarios that could lead to different damage states initiated by either hardware failure, human error, or external events. In the context of a spacecraft risk assessment, radiation may be considered as an external event and analyzed in the same basic way as any other contributor to risk. It is possible to turn up the microscope on any particular contributor to risk and ask more detailed questions than might be necessary to simply assess safety. The methods of QRA allow for as much fine structure in the analysis as is desired. For the purpose of developing a basis for comprehensive risk management and considering the tendency to open-quotes fear anything nuclear,close quotes radiation risk is a prime candidate for examination beyond that necessary to answer the basic question of risk. Thus, rather than considering only the customary damage states of fatalities or loss of a spacecraft, it is suggested that the full range of damage be analyzed to quantify radiation risk. Radiation dose levels in the form of a risk curve accomplish such a result. If the risk curve is the complementary cumulative distribution function, then it answers the extended question of what is the likelihood of receiving a specific dose of radiation or greater. Such results can be converted to specific health effects as desired. Knowing the full range of the radiation risk of a space mission and the contributors to that risk provides the information necessary to take risk management actions [operational, design, scheduling of missions around solar particle events (SPE), etc.] that clearly control radiation exposure