I'm confused. You call for tiles to be become irradiated and permanently unworkable yet I think that scrubbing would clean up the damage.
That's why I said remove the ability to scrub the fallout. The fallout would be permanent and the tiles unworkable.
Also I don't think a nuke would completely destroy a city. If you have watched 24 season 6. You will see how a suitcase nuke was set off in the city. If a city is to be destroyed then if should depend on the size.
You're referencing a TV show to how a nuke would effect a city?
Nobody knows what a modern nuclear ICBM would do to a city, it may not level it, but it would be uninhabitable afterwards. A tactical nuke or suitcase bomb wouldn't do as much physical damage, but the radioactive contamination would probably cause the city to be evacuated permanently.
There are no real world examples of a nuclear attack on a city, thankfully, and hopefully there never will. The closest thing to compare would be the Chernobyl nuclear disaster. It wasn't an ICBM, tactical nuke or suitcase bomb and there was no explosion to level buildings (except for the steam explosion that blew the reactor building's roof off), but the
radioactive contamination caused the evacuation of around 2,000 cities, towns and villages in the Ukraine and Belarus. The cities are still deserted and the land can not be farmed. There are still restrictions on the production, transportation and consumption of food contaminated by Chernobyl fallout, even in places as far away as the UK, Germany, Austria, Italy, Sweden and Finland.
My point is that I think nukes in the game should have permanent side effects, like they would in reality, to make them a last resort weapon. Perhaps when you use an ICBM on a city, some of the population is killed and the rest is distributed to nearby cities as permanent
(i.e. surviving evacuees), and permanent
spreads to all cities on the same continent the nuke was used on, in addition to the surrounding tiles being permanently radioactive and unusable. You definitely wouldn't nuke your neighbor knowing some of the fallout might spread throughout your cities.
Perhaps when you deploy a tactical/suitcase nuke in a city, you can choose to target military units, city defenses or buildings, but the side effects would be permanent
in the city for the radioactive fallout within the city and permanent
would also spread to nearby cities.
And I don't think that nukes can cause different sizes of damage. If they can then then they need to kinds. Hydrogen and Atomic. There would be four kinds. Hydrogen ICBMs and Hydrogen Tacticals. Atomic ICBMs and Atomic Tacticals. The Hydrogens would require more
but would cause more destruction.
I was just referring to the different size nukes such as the tactical nuke and ICBM, and since you brought it up a suitcase nuke. I do like your idea of a suitcase nuke as an espionage weapon. It could do the same damage as a tactical nuke, but if the origin of the civ who deployed it is revealed, then there would be huge diplomatic penalties (maybe every civ declaring war on you).
radiation sickness and events like cancer in this city , cause unhappy people , minus 5 GPT for 25 turns in this city due to increased healthcare , etc , ...
Have a Nuclear Day 
