China might be able to have a better crack in the long term at developing nuclear explosion propulsion (Orion revised - acctope) just because it previously failed to jump a similar development hurdle around 900AD. Not unlike today the "ingredients" of gunpowder were a super-secret, which led many to speculate incorrectly. The basic challenge of the physical containment of gunpowder within a cannon (which is really nothing more than a hollow tube closed by a single pusher-plate) was left to the European engineers. After many, many centuries China appears almost at the forefront of technology again. One could argue that any inventor nation of a new and very different type of "explosive" reaction might naturally fail to see the correct development path. Certainly that was the case with China when it invented gunpowder. Perhaps nuclear energy will always be almost as irrelevant as fireworks have been to industrial progress. Propulsion in space (and not starting from the ground) has none of the pollution problems.
There are many ingenious designs for such propulsion systems, but IMHO they appear to be missing the basic point. It took hundreds of years for the gunsmiths to come up with the modern gun cartridge. If you apply the same fabrication techniques to this new 20th century "gunpowder" in space, while it is on a much larger design scale, why should the design details be any different from what is in common use today? That is to say a smooth barrel and a filled "gunpowder" cartridge that is ejected immediately after use? This would of course effect propulsion from a ricochet rather than fire any projectile, but the design is basically the same as a "Smith and Wesson". America however, rather like the Chinese therefore them, in being the actual inventor of the new ingredient, do little to develop the potential in reality. It comes to reason that history has turned a full circle and America has invented the ingredient and risks falling into the obscurity that engulfed China. Since the cost of building such a test device in space would be hundreds of billions of dollars, and expectations of any star flights unacceptable to so many, I suggest the first step is an elevator application. ACCTOPE (Atomic Chemical Counter Thrust Orbiting Payload Elevator) could provide the payload pull in the many thousands of tons and thus justify investment. A bit like fly-fishing with a line tied to a Smith and Wesson and using the ricochet to pull the line!
The risk however, rather like in testing many light-bulb filaments, would be containment failures that damage existing orbiting satellite. Especially so since much like early cannon prototypes, our large tonnage cannons of 500 tons and possibly greater, would by necessity be constructed out of several segments by space-station based astronauts. Until the first tube is built, tested and used to haul up it's twin sister, that first construcion is going to have to be painfully made out of pieces from many old-fashioned chemical rocket launches. There is no easy way around this. China might thus be eventually the most enthusiastic nation to invest in and bankroll such a project a few years hence, simply because they have history is this prickly area of invention and application failure.
