You have the H-Bomb to replace the ICBM, aren't they 2 completely different things? H-Bomb don't just shoot out of the ground and level some one that is 2000 kilmoters away, they are dropped from planes. What you would need is 3 new classes of unit.
Your atomic bomber would be one. And your H-Bomb and Tactical Nuke another. And nuclear capable submarine would be the last one.
You bomber which would have to be a unit that can load a built atomic bomb and drop it like the tactical nuke in Civ 3. The Bomber would act like a gunship that could move over water and land which would leave it open to plausable interception. The speed at which the bomber moves would vary with the generaltion. And at a certain range a bombing mission could be launched.
The Second would be loadable bombs like like the Civ3 Tactical nuke. The range from a target from which the bombing mission could be launched would depend on the generation of pay load. The Distructive power too would vary from generatio to generation.
The last type would be the naval strike unit like it would be like the arial version but only capable of carring missle type pay loads.
Bomber Class
It would act sort of like an air carrier, you could load bombs or base fighters too it. The Fighters would only be able to recon, air supremacy and rebase while attached to the bomber. The number units that make up a squadron would very on the weapon class:
Bomber - 3
Heavy Bomber - 2
Spy/First Strike - 1
It is really more of a visual thing.
1st Generation - B-29 SuperFortress (The Enola Gay was one)
Movement - 3 squares per turn.
Capacity - 3 bomb type pay load or fighter escort only.
Tech: Flight
Resources: Oil
Benefit: Cheap and avaiable
Weapon Class: Bomber
2nd Genration - B-52 Stratofortress (cool ass name)
Movement - 5 Squares per turn.
Capacity - 8 Bomb type pay load or fighter ecort only.
Tech: Flight and Rocketry
Resources: Iron, Oil
Benefit: Huge Cargo load, moderate speed
Weapon Class: Heavy Bomber
2nd Generation - U2
Movement - 6 squares per turn invisible. (unless enemy has rocketry)
Capacity - 0
Tech: Rocketry and Flight
Resources: Oil, Aluminum
Benefit: Long Term Reconissance
Weapon Class: Spy
3rd Generation - B-2 Spirit
Movement - 8 squares per turn invisible (unless enemy has satilites)
Capacity - 4 bomb or rocket or fighter jet escort type payload only.
Tech: Flight, Computers, Rocketry and Composites
Resources: Aluminum, Uranium, Oil
Benefit: Moderate Cargo, fast, toughtest intercept
Weapon Class: First Strike
Pay Load Class
2 distinct types. Bomb Types which only have very short Ranges and can very in power emensely but only have short bombing mission ranges. Or missle types stronger than some bombs but weaker than others the great advantage is that you can launch from further away. The distructive power, think in nuclear terms, it might say low but that is still deadly. Fallout range it double the destructive range.
Bombs
1st Generation - Little boy
Mission range - 1 square all directions
Destructive Power - Low
Destructive Radius - Target Square only
Capacity Occupancy - 1 cargo space
Tech: Flight and Fission
Resources: Uranium, Iron
Benefit: Cheap yet still deadly
1st Generation - Fat Man
Mission Range - 1 square all directions
Destructive Power - Moderate
Destructive Radius - Target Square Only
Capacity Occupancy - 2 cargo spaces
Tech: Flight and Fission
Resources: Uranium, Iron
Benefit: A little more bang for your buck early on.
2nd Generation - H-Bomb
Mission Range - 2 square all directions (if launched by a b-29 the b-29 had a 5% chance of being destroyed)
Destructive Power - High
Destructive Radius - 2 square in every direction of targeted squares
Capacity Occupancy - 2 cargo spaces
Tech: Flight, Fission and Electricity
Resources: Uranium, Iron
Benefit: A real show stopper
3rd Generation - Zeus (Its a real bomb)
Mission Range - 3 square all directions (If launched by a B-52 the B-52 has a 5% chance of beign destroyed)
Destructive Power - Unparallelled
Destructive Radius - 4 Square Surrounding the target square
Capacity Occupancy - 4 cargo spaces
Tech: Flight, Fission and Computers
Resources: Uranium, Aluminum
Benefit: The finger of god.
4th Generation - Bunker Buster
Mission Range - 2 square all directions
Destructive Power - Extreme
Destructive Radius - Only the traget square (fall out only occurs in the square itself)
Capacity Occupancy - 2 cargo spaces
Tech: Satelites, Composites and Computers
Resources: Uranium, Aluminum
Benefit: Consice and vastly effective.
Missels
1st Generation - Nuclear Missle
Mission Range - 4 square all directions
Destructive Power - Moderate
Destructive Radius - Target Square Only
Capacity Occupancy - 1 cargo spaces
Tech: Rocketry, Fission and Electricity
Resources: Uranium, Oil, Iron
Benefit: Long range, powerful and concice
2nd Generation - Tactical Nuke
Mission Range - 8 square all directions
Destructive Power - High
Destructive Radius - 1 square in every direction of teh target square
Capacity Occupancy - 2 cargo spaces
Tech: Rocketry, Fission, Satelites, Computers
Resources: Uranium, Aluminum, Oil
Benefit: Long range, and deadly
3rd Generation - ICBM
Mission Range - infinite square all directions
Destructive Power - Extreme
Destructive Radius - 2 squares in every direction of the target square
Capacity Occupancy - 5 cargo spaces
Tech: Satelites, Compters, Composites, Robotics
Resources: Uranium, Aluminum, Oil
Benefit: Check mate.
Strike Boat Class The strike boad class is made up by submarines wich unlike the bomb and bomber classes could attack other units so they cary an attack power rating on top of capacity.
1st Generation - Nuclear Sub
Movement - 3 squares per turn invisible like any other submarine
Capacity - 8 rocket type payload only
Attack Power: regular sub -5
Tech: Radio, Fission and Combustion
Resources: Iron, Oil
Benefit: Huge Cargo early on
2nd Generation - Strike Boat
Movement - 10 squares per turn invisible like any other submarine
Capacity - 3 rocket type payload only
Attack Power: regular sub +5
Tech: Computers, Fission and Rocketry
Resources: Aluminum, Uranium
Benefit: Fast strong still about to deliver
3nd Generation - Boomer
Movement - 4 squares per turn invisible like any other submarine
Capacity - 40 rocket type or 3 marine payload only, never both
Attack Power: regular sub -2
Tech: Computers, Composites and Satelites
Resources: Aluminum, Uranium
Benefit: The deliverer
The only new structure would be the silo which woud be an upragde of the fort improvement would allow the lauching of missle type nukes from forts. Launching nukes from cities is very unrealistic.
The only new ground unit would be the Freight Truck, which could be loaded up with only 1 nuke at a time regardless of size so that it could be moved from site to site. Movement 2 squares per turn. Avaiable with combustion. Nukes of all types can also move one square a turn on frendly rail roads but many not launch.
Other non nuclear pay loads like air bourne infantry and regular bombs could be added too just to spice it up.
that is my take on an accurate and vastly more expanded nuclear play.
more useful and realistic to the game. I miss some parts of nuke system from civ 3 conquest.
for me its to expencive 
)
similar to Hit Singles or Hit Musicals
so you can make real test 
) :
