Circle Bomb Script Won't Work?

First, I tabbed your code. Look bellow for finished code:

notBeenTouched = true
-- Not sure why wait(4) was here
function onTouch(hit)
	if hit.Parent:FindFirstChild("Humanoid") then -- We want players to activate! 
	    if notBeenTouched then  
		    notBeenTouched = false  -- We want this not to be spammed, so change notBeenTouched before anything else occurs
			local NukeBall = Instance.new("Part", game.Workspace)
			function onBombTouch(Hit)
				Hit:BreakJoints()
			end
			NukeBall.Touched:connect(onBombTouch)
		    NukeBall.Shape = "Ball"
		    NukeBall.BrickColor = BrickColor.new("Deep orange")
		    NukeBall.CanCollide = false 
		    NukeBall.Anchored = true
		    for i = 5, 100, 5 do    
			    print(i)
			    NukeBall.Size = Vector3.new((i), (i) ,(i))          
			    wait(0.1)       
		    end
		    NukeBall.Transparency = 0.5
		    wait(0.5)   
		    NukeBall.Transparency = 1
		    NukeBall:remove()
			notBeenTouched = true -- Lets this function Again
		end
    end
end

script.Parent.Touched:connect(onTouch)

Now, You need to place your explosion somewhere, this script doesn't seem to do that! First, when the NukeBall is created, we want to make a touched event connected to that, so after it was made, I began the function. Now, you want to start the listening of this event (When you use :connect) before the size is expanded, if not, anything touching during that expansion will be unaffected! Not quite what you'd want. At the end, I made your variable notBeenTouched true again, this will make the script run another time after the nuke is complete. Remove this variable's change to true if you do not want it to occur again!

Comment if you have questions! Otherwise, toss a +1 rep if this helps!