"This memorandum updates the process for launches of spacecraft containing space nuclear systems," the document said on Tuesday. "The ability to use space nuclear systems safely and sustainably is vital to maintaining and advancing United States dominance and strategic leadership in space."
Space nuclear systems include radioisotope power systems such as radioisotope thermoelectric generators and radioisotope heater units as well as fission reactors that can be utilized for power and propulsion, the National Security Presidential Memorandum said.
The new procedures and safety guidelines approved in the memo "are forward-looking and amenable to effective use of space nuclear systems for heating, power, and propulsion," the National Security Presidential Memorandum said.
Any nuclear accident in space resulting in exposure in the range of 5 rem to 25 rem total effective dose of radioactivity to any member of the public was deemed extremely unlikely and the probability of such an event did not exceed one in 10,000, the National Security Presidential Memorandum added.