The nuclear fuel used in many nuclear reactors is uranium-235. When bombarded with a single slow neutron, a ²³⁵U nuclide undergoes fission to form ¹⁴¹Ba, 3 neutrons, and another nuclide "X". Identify the nuclide X, Write its symbol.

Briefly explain why uranium fuel rods in nuclear reactors cannot be used in atomic weapons without further processing.

Expound on why fusion is more beneficial than fission as a nuclear energy source in terms of availability and hazard. Despite its prospect as an almost inexhaustible energy source, explain why fusion reactors have not been developed yet.