Rod assembly for nuclear reactors

A multi-segment fuel rod for use in a nuclear reactor, the multi-segment rod comprising:

• a plurality of rod segments,
• the rod segments being removably mated to each other in an axial direction,
• the rod segments being individually cladded, and
• the rod segments forming a continuous multi-segment rod having continuous cladding in the axial direction when mated in the axial direction;
• at least one containment assembly disposed within at least one of the rod segments;
• and
• at least one irradiation target sealed within the at least one containment assembly so as to provide double containment for the at least one irradiation target and products formed from the at least one irradiation target when exposed to a neutron flux, the at least one containment assembly housing isotopes, the isotopes only having an atomic number greater than 3 and less than 90.