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 trade-offs for a nuclear system? Nuclear systems have many interacting subsystems and there are many choices and trade-offs to consider, with a multitude of effects on safety and cost, both subtle and drastic. Many of the choices are not straightforward to understand or predict.
For introductory purposes, we can distill the many technology choices to just a few: 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 thousands of 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
| 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,∞] MWth |
| Temperatures | [150-1050 °C], 2000 °C+ for Nuclear Thermal Propulsion |