Physics & Reactivity
Nuclear Physics: Fast Spectrum
Traditional Light Water Reactors (LWRs) use water to “moderate” (slow down) neutrons. ReCore.One uses liquid sodium, which allows neutrons to remain at high energy levels—the Fast Spectrum.
Why “Fast” Matters
Fast neutrons have the energy required to “fission” (split) heavy elements like Plutonium, Americium, and Curium (the Actinides).
- In a Slow Reactor: These elements build up as long-lived waste because “slow” neutrons are often absorbed without splitting the nucleus.
- In a Fast Reactor: These elements become high-energy fuel. This is the key to Actinide Burning.
Fertile vs. Fissile: Unlocking the 99%
Traditional reactors only use Uranium-235, which represents less than 1% of natural uranium. The remaining 99% (Uranium-238) is discarded as “depleted uranium.”
Transmutation as Fuel Creation
In the Fast Spectrum, a neutron can be absorbed by “fertile” U-238, transmuting it into “fissile” Plutonium-239.
- LWRs: Treat U-238 as a waste product.
- ReCore.One: Uses U-238 as a massive energy reserve. By converting fertile material into fuel, we unlock 100x more energy from the same amount of uranium, eliminating the need for new mining for centuries.
The Sodium Safety Margin
The physics of the coolant is just as important as the physics of the fuel.
Thermal Inertia & Pressure
- The Water Problem: Water boils at 100°C. To keep it liquid at reactor temperatures (300°C), it must be kept under 150 bars of pressure. If the pressure vessel fails, the water flashes to steam instantly.
- The Sodium Advantage: Sodium does not boil until ~881 °C. The ReCore-Reactor operates at ~600 °C and atmospheric pressure.
- The Result: We have a 281 °C safety buffer. Even if all cooling systems fail, the sodium remains a liquid, continuing to move heat away from the core through natural circulation without any risk of a pressure explosion.
Physics Comparison: Thermal vs. Fast Spectrum
Understanding the physics of the ReCore-Reactor requires looking at how we manage neutrons.
Thermal Reactors (The 20th Century Standard)
Most reactors in operation today are Thermal Reactors.
- The Moderator: They rely on “moderators” (water, graphite) to slow neutrons down to thermal speeds. This is necessary because the U-235 fuel is rare, and slow neutrons are more likely to fission it.
- The Risk: This moderator also acts as a “buffer.” If the reactor power increases, the moderator expands, which can sometimes lead to a “positive” feedback if the physics aren’t perfectly managed (e.g., the Chernobyl RBMK).
Fast Reactors (The ReCore Approach)
Fast reactors operate without a moderator, allowing neutrons to remain at high kinetic speeds.
- The Advantage: Fast neutrons don’t care if the fuel is U-235 or U-238, or a Transuranic actinide. They have the energy to split any heavy nucleus.
- Inherent Safety: Because there is no moderator, the reactor’s behavior is dictated purely by the fuel and the coolant. By using a “flat” core design and metallic fuel that expands with heat, we create a system that is physically unable to go into an uncontrolled power excursion. The physics of the ReCore-Reactor are self-regulating: if the temperature rises, the reaction slows down immediately and passively.
Void Coefficient
The Void Coefficient describes how the reactor’s power changes if the coolant (sodium) is lost or forms a “void” (bubble).
- Positive Coefficient (Unsafe): If coolant is lost, the power increases (e.g., the RBMK design at Chernobyl).
- Negative Coefficient (Safe): If coolant is lost, the reactor power decreases and the reaction stops.
- ReCore-Reactor Design: Through a specific “flat” core geometry, we ensure that any loss of sodium density results in a reduction of reactivity.
Negative Temperature Coefficient
As the metallic fuel heats up, it physically expands. This expansion increases the distance between atoms, making it harder for neutrons to maintain the chain reaction. This is an Inherent Passive Shutdown—the hotter the reactor gets, the more it pushes itself toward a shutdown state.