I tried to searching on forum, but I don't think I found any solid answers yet.
I play on prefab large 1 and it looks like there is no titanium in the radioactive area. Every rock have either iron/coal/lead/nitrate, which is strange, since I thought this was disabled since A17 or so, or in some rare cases plutonium. I tried to dig underground but only Iron can be found. Kinda frustrating