Reactor Architectures
There are many ways to design a nuclear reactor to extract and utilize the nuclear heat. What are the principal design choices and trades for a nuclear system? Nuclear systems have many interacting subsystems and there are many choices and trades to consider with a multitude of effects on safety and cost, both subtle and drastic. And many of the choices are not straightforward to understand or predict.
For introductory purposes, we can distill the many technology choices to just a couple: fuel, coolant, temperature, size, and power rating as listed in the table below. Each usually has some partisan zealot, championing a particular choice and design path. As designers, we are forced to down-select technologies and we cannot forever be open to all the thousand combinations of reactor technologies. The diversity of design possibilities suggests many ways to the same end, but the fact is that one architecture can be best for a given set of goals.
There's a fun random reactor generator at (whatisnuclear.com)[https://whatisnuclear.com/random.html]
| Parameter | Options |
|---|---|
| Fuel Form | Oxide, carbide, nitride, metallic, molten salt, liquid metal. |
| Fuel Wrapper and Geometry | TRISO-matrix, metallic clad, ceramic clad, no clad, (geometry: cylinders, annuli, pebbles), fuel wrapped moderator |
| Fuel Type and Cycle / Enrichment | LEU converter, Natural U converter, HALEU converter, HEU burner, Pu burner, U-Pu breeder, Th-U breeder |
| Coolant and pressure | Helium, water, CO2, sodium, sodium heat pipe, molten salt (fluoride or chloride), other liquid metals, organic, other gases (H2, N2, air). Pressures of 1-15 MPa, typically 3-7 MPa for He |
| Moderator / Reflector | Graphite, water, heavy water, hydrides, Beryllium (no clad, ceramic, or metallic clad, composite / entrained) |
| Size | Physical dimension of the reactor [~1-6m diameter, 1-20m height] |
| Power Rating | Power rating per reactor core [0,inf] MWth |
| Temperatures | [150-1050 °C], 2000 °C+ for Nuclear Thermal Propulsion |