Worst part to me is the truly HUGE size (and cost!) it would need to be as per your idea, in order to have a NPP onboard, the huge antennae / power capability you suggest and something similar to the electronic equipment of an AWACS (20 ton electronics in case of A-100).
Well no these nuclear power plants are compact and designed for use in relatively small things like torpedoes and space craft and trains.
That is the point... they are not excessively big and heavy.
Myself I had though previously on some kind of flat, smaller airship of something like 20 m diameter (maybe more, depending on payload needs), unmanned, tethered that could be lowered and carried onboard in case of very bad weather / repair or enemy attack. But yours has strong points too...
The advantage of a tether is that you can use it for power and fibre optic data transmission so the raw data can be sent down from the radar array to the ship for processing without a datalink (ie electronic traffic that could be intercepted).
The thing is that if the alternative is a nuclear powered electric motor driven airship it could support a carrier group but is not tied to it... you could use it independently of ships... so if a storm is brewing it can climb above it and there wont be a ship at the other end of the line being rocked and rolled about.
A tethered airship might get damaged in a storm and of course there is the risk of attracting lightning strikes too... plus a fully independent airship could operate above the effective altitude of most enemy fighters... 20-30km altitude which would give it an excellent view of the surrounding area.
A large blimp could also fit enormous VHF and lower frequency AESA arrays as well as high frequency antenna too... to communicate with submarines the Tu-142 is not ideal because to use its ULF antenna the antenna which is over 1km long needs to hang nearly vertically, which requires low flight speed that is close to stall speed... for an airship it would just be a case of dropping a cable... it could also be designed to be able to land on the sea surface and would be an ideal replacement for amphibious aircraft.
And like I have said with modern carbon fibre and kevlar and nomex materials it could be fire proof... purge the gaps between the hydrogen filled bags with nitrogen so even if there are sparks or even a flare or incendiary round in there it wont even burn... hydrogen wont burn without oxygen... even a smouldering piece of paper would go out without air, or more accurately the oxygen in the air.
This blimp could be a full AWACS platform with processing and command and control... it could even have self defence missiles... an airborne TOR and Pantsir system with 9M100 there too to defend it from attack... its best defence would be dumping all ballast and climbing to 25km altitude where no enemy fighter could reach it...
I see it as a downsized radar station which is floating on air... in the same manner as US aircraft carrier is a downsized airbase floating on water. Which means we have a mobile radar base flying together with the naval fleet or closely following the ground forces near the battlefield.
Agreed except its internal capacity could mean it is more like a building sized OTH radar in an airship and therefore superior to land based AWACS platforms based on airliners like Sentry and A-100.
You could make different sized models with different sized radars... you could even make a diesel and solar powered model for export with rather less powerful radar arrays.... you don't need super dooper radars... the fact that it is up in the air and its radar horizon is thousands of kms away from the ships it is operating above is enough to make it able to see any low flying threat... the enormous size allows a wide bandwidth range, but new photonic radars might make it all seeing anyway...
But the largest disadvantage of airship is speed. In comparison with aircraft, airship are tortoise. Nowadays, slow flying thing is highly vulnerable. Hopefully a strong power generator like nuclear engine may solve this problem ? But then again which kind of design allows the airship to handle the risky nuclear reactor and all its heat.
Here I disagree... speed is of no value to an AWACS platform supporting ships... being able to hover on the spot for days and weeks is actually more useful... the main disadvantage of helicopter based AEW is not lack of speed... it is lack of altitude and limited weight capacity for all the electronics and the radar array... none of which would be an issue.
As for vulnerability it could be armed... and it could be designed with excessive lift capacity... its party trick would be to dump ballast and climb to very high altitude where blast fragmentation warheads in AAMs and SAMs are rather less effective, where fires wont naturally burn... if you think of the volume of an airship 300m long and perhaps 40m wide and maybe 20m high... what sort of area with the fragments from one AAM do damage considering the gas bags will be carbon fibre and kevlar and nomex and the structure will be fibreglass and carbon fibre... even a clean hit that detonates might destroy 20 cubic metres of hydrogen bags.... so what is going to happen... it will of course start to descend... but we are not talking about a Yak-44 who just took an AMRAAM hit and has lost a wing or suffered serious structural damage and was flying at 450km/h horizontally and is now crashing downwards and 600km/h and accelerating from 10,000m.
The airship could dump ballast after the hit and it might actually stop descending... what other AWACS platform could do that?
Of course it wont be invincible, but it could carry self defence jammers and decoys and even self defence guns and missiles... but it probably would not even need all that because anything approaching it will be detected at very long range whether it is flying high or low and it will probably be operating over a Russian carrier surface action group armed to the teeth with naval variants of all the latest Russian SAMs... not to mention the aircraft from the carrier that could also protect the airship as well as themselves and the ships they are operating with.
The easiest way of dealing with heat from the reactor is to pump the nitrogen between the hydrogen air bags through the reactor to heat up... pumping that through the hydrogen airbags will heat up both the nitrogen and they hydrogen... making it an even more efficient lifting gas.
That will make the airship stand out as an IR target but antenna arrays this size and power are going to generate a lot of heat anyway so there is really nothing you could do about that... operating at very high altitude would require max lift so the heat would be valuable... and as soon as a radar is turned on the airship could be detected from very long range....