Hi!
Open cycle nuclear rocket engine which contaminate space!? 
M-19-1 picture by ucon-san.
http://www.secretprojects.co.uk/forum/index.php?action=dlattach;topic=18507.0;attach=55733;image
M-19-1 three side view drawing by ucon-san.
http://www.secretprojects.co.uk/forum/index.php?action=dlattach;topic=18507.0;attach=55735;image
https://falsesteps.wordpress.com/2016/09/24/m-19-gurkolyot-grab-the-problem-by-the-throat-not-the-tail/
"Weighing in at 500 tonnes with fuel, the M-19 was a very flat, 69-meter long triangular wedge with two small sets of wings, one at the tail and one as canards near the nose.
Launching horizontally from a runway, the M-19’s trip to orbit would begin with twin(set of?) turbofan jet engines(Please watch No.3 picture) burning liquid hydrogen. After getting up to Mach 4, the plane would switch over to scramjet engines(Please watch bottom of bottom picture), also burning hydrogen. In both cases, though, the engines had Gurko’s idea behind them for a little extra kick.
The M-19 would have had a nuclear rocket engine that would take over in turn once the scramjet pushed the plane to Mach 16 and out of the appreciable atmosphere around 50 kilometers high. As the reactor was just sitting there during the turbojets’ and scramjets’ operation, Gurko reasoned, why not use it to superheat their exhaust to increase thrust? The potential increase in efficiency was considerable, and as the nuclear rocket (already more efficient than chemical rockets) would only be used for the final leg, the low inherent fuel use of the air-fed turbo- and scramjets gave the M-19 a tremendous payload fraction: the 500-tonne fully fueled plane was projected to lift 40 tonnes to LEO in its 15m × 4m cargo bay, which compares favorably to even staged rockets. Consider the Space Shuttle at 2040 tonnes and 28 tonnes of payload, or the Saturn V at 3038 tonnes and 118 tonnes of payload. To move whatever was stored in it, the bay was to be equipped with a manipulator unit, and an airlock from the crew compartment allowed EVA. Behind the bay was a large LH2 tank and, it should be made clear, no oxidizer tank. The rocket would run on raw hydrogen, while the two different types of jet would use the air as their source of oxygen.
After completing its mission in orbit, the M-19 would then fly back home, using the same propulsion systems in reverse order to come into a powered landing at an airstrip somewhere in the USSR, with an astonishing cross-range capability of 4500 kilometers. This completely plane-like return was of considerable interest to Soviet space planners for other reasons too, as it meant that the M-19 would reduce search and retrieval costs to nil as compared to capsules unless there was an emergency. Under those circumstances the cabin was to be entirely ejectable, serving as a survival capsule for the three to seven cosmonauts that might be on-board."
Other images source.
http://www.testpilot.ru/russia/myasishchev/m/19/img/
Nuclear rocket engine does not need Oxidant.(M-19 weight and space saving engine.)
