Fuel bundle with twisted ribbon fuel rodlets for nuclear thermal propulsion applications, structures for manufacture, and methods of manufacture

A method of manufacturing a fuel bundle, the method comprising:

• forming a core region of the fuel bundle, wherein forming the core region includes seating first ends of each of a plurality of twisted ribbon fuel rodlets in a respective receiving space of a rodlet seating fixture, wherein the rodlet seating fixture includes a seating surface having a plurality of protrusions, the plurality of protrusions are distributed on the seating surface and have a height from a base surface of the seating surface, and side surfaces of a plurality of adjacent protrusions define the respective receiving space;
• attaching an end cap to second ends of each of the plurality of twisted ribbon fuel rodlets to form a pre-bundle;
• optionally introducing an infiltrant into the pre-bundle to occupy void spaces in the assembled twisted ribbon fuel rodlets;
• encasing the pre-bundle in a multilayer casing including an inner layer, an inner intermediate layer, an outer intermediate layer, and an outer layer;
• removing the rodlet seating fixture and end cap;
• and
• optionally removing the infiltrant,
• wherein the plurality of twisted ribbon fuel rodlets have a composition including a fissionable fuel component,
• wherein the inner layer is a graphite compressive felt insulation layer,
• wherein the inner intermediate layer is a composite reinforcement and compressive layer,
• wherein the outer intermediate layer is a first compressive prepeg layer, and
• wherein the outer layer is a second compressive prepeg layer.