Yes, it's extremely easy to make a mod that turns off nukes altogether. The simplest way is to just set their costs to -1, making them unbuildable. Note that this'd have several other impacts, like increasing the number of Nuclear Plants people build (since other than the GDR, there'd be no reason to save Uranium). But if you're just completely anti-nuke, it's the easiest way to deal with them.
There are also mods, like my own (in .sig), that add interception mechanisms to nukes, to where you can build an SDI project that shoots them down part of the time. This requires a little knowledge of Lua programming, as the existing stubs do nothing, but it's not very complicated.
And if you just want to keep nukes in the game but reduce the numbers that get built, there are several ways to do that as well.