Dose calculations for nuclear thermal rocket exhaust
Nuclear and Emerging Technologies for Space, NETS 2013
Nuclear thermal rockets (NTR) have the potential to greatly enhance payloads from low earth orbit to Mars, the Moon, or other deep space destinations. NTR tests at the Nevada Test Site in the 1960s produced some release of radioactive fission products in the rocket exhaust. This release came from some degradation of the surface coating on the reactor fuel and coolant channels during the high-temperature operation. This paper estimates the potential doses and health effects to populations on Earth should comparable releases occur during NTR thrusting in low earth orbit during a mission to Mars or other destinations. A multi-compartment atmospheric model is developed to track the time needed for exhaust components to reach the surface of the earth. Isotopic decay is included in this model. Because most fission products have a short half-life and the time for aerosols to reach the earth's surface is many years, very little radioactive material reaches the earth's surface. The average dose per person from a typical NTR thrusting operation in low earth orbit (using the NTR designs of the 1960s) is calculated to be about 1E-08 of the dose received from natural background radiation.