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.