What is the role of nuclear weapons in that future world?

I think that nuclear weapons are useless in the world because it is just weapon, it can be the thing that protect each country but that is all what it has. We might be facing another world war due to the realationship among the most powerful countries which are Russia, China and USA. They have a previlleage to have nuclear bombs but they don\'t allow other countries to have it. It doesn\'t make sense. Although, major countries ban other countries to possess nuclear weapons, some has tried to test their weapons because they would like to show their strength to the world. It\'s purpose must be protection of their countries. It should not use for treathening others. Radiation is really useful in our lives, if we use it in a right way, such as medical purpose or industrial one. It is also the best material to produce electricty with lower expenses. So, I don\'t want the world to try to develop their nuclear weapon, I want them to invent novel way to use it.