[ RadSafe ] Space Propulsion; Enriched Uranium

[John Ahlquist]

In the 1950s and 60s the US had Project Rover to develop nuclear rocket engines 
for deep space propulsion.  The largest reactor, Phoebus 2A [core about 4 ft 
diameter and 4 ft high], ran at 4000 MW[t].  It was fueled by HEU beads in a 
graphite matrix and cooled by liquid hydrogen.  The Project was phased out in 
the late 60s due to lack of a defined mission.