BUENOS AIRES, Oct 18 (Reuters) - International Atomic Energy Agency (IAEA) chief Rafael Grossi expects to return "soon" to Ukraine, he told Reuters on Tuesday, amid negotiations to establish a security protection zone around the Russian-occupied Zaporizhzhia nuclear power plant. The talks are seen as key to defusing concerns that have mounted since August about the risks of shelling at or near Zaporizhzhia, Europe's largest nuclear power station. Russia and Ukraine have both blamed each other for the shelling. The head of the IAEA, the U.N. nuclear watchdog, said that separate Russian threats to use nuclear weapons in Ukraine could not be ruled out but that it was "not an immediate possibility". "I believe that the possibility of Russia using nuclear weapons is not an immediate possibility.

---