Thermal Neutrons
Neutrons with low kinetic energy, typically 0.025 eV at room temperature, in thermal equilibrium with surrounding moderator material.
Thermal neutrons have energies around kT where T=293K, making them ideal for fission in U-235 due to higher cross-sections. They result from slowing fast neutrons via elastic scattering in moderators like light water or graphite. In light water reactors, thermal neutrons sustain the chain reaction with enrichment levels of 3-5% U-235.
Why it matters now
Thermal neutrons are central to LWR and PWR designs dominating 90% of global nuclear capacity, critical for SMR licensing in 2025-2026 as data center PPAs demand reliable baseload power.