Its pretty hopeless to expect ground-to-orbit nuclear
rocket propulsion any time in the foreseeable future.
On the other hand, radiation shielding material is not the type of thing that needs to be sent up in one big chunk, so certain alternative methods may be useful (this also goes for other types of bulk materials like water and rocket propellants for supplying space stations and interplanetary space ships, as well as for "micro-satellites" based on advanced electronics & nanotechnology).
One such potential bulk material launch system relies on nuclear power stations to energize large lasers which propel small spacecraft to orbit, as illustrated below. The concept has already been proven with laboratory sub-scale tests, but so far there does not appear to have been an urgent need to develop a full-scale version of this "conveyor belt to space." Nonetheless, its interesting because it shows that its more likely that we will be beaming nuclear power into space, rather than solar power down to earth :-)
From: AtomicRod@aol.com [mailto:AtomicRod@aol.com]
Sent: Sunday October 27, 2002 4:36 AM
Subject: Re: [cdn-nucl-l] Space station radiation shields
NASA is ripe for a paradigm shift. Engineers there have always been obsessed
about reducing weight; they know that every additional kilogram in payload or
in the space vehicles themselves represents several additional kilograms in
rocket fuel required to get off of the earth and into space.
The paradigm would shift dramatically if a more compact fuel source were used.
Nuclear rockets would enable the lifting of heavier space vehicles, thus
allowing the use of better shielding material and significantly reducing
exposure from cosmic radiation.