How did the NERVA project solve the nuclear radiation problem?

As the RNS tank or tanks emptied, crew radiation dose would thus steadily increase. To solve this problem, NAR had developed a "stand-pipe" single-tank RNS concept, in which a cylindrical "central column" running the length of the main tank stood between the crew and the NERVA I engine. read more

NERVA reactors were fueled with uranium, which was contained in graphite elements with channels running through them for the propellant (liquid hydrogen) to flow through. Very simple, and fairly effective, though the propellant flow was inadequate for a surface-to-orbit rocket. read more

Nuclear rockets use hydrogen, whereas U.S. power plants use water. Hydrogen is the best propellant gas for a nuclear-thermal rocket. Nevertheless, working with hydrogen at these high temperatures presents many challenges. It Comes Down to the Cores. All the Project Rover/NERVA reactors had solid cores. read more