Criteria for establishing nuclear power system radiation levels for a spacecraft

An approach for assessing the allowable radiation levels for a nuclear power source is presented. The orbital and nuclear threat environment in which a spacecraft must function is described, and the ability of electronic components to survive in a radiation environment is examined. Options that reduce unacceptable radiation levels emanating from a nuclear power source are discussed. These involves the use of shielding and distance. Shielding is most effective when applied at the reactor. However, the susceptibility of sensors and other particularly sensitive electronic components may in certain cases justify spot shielding. The shielding effectiveness and associated weight penalty depends on the specific reactor design characteristics