How do nuclear reactors use the weak force in their fuel cycles?

Nuclear reactors rely mainly on fission, but the weak force plays a crucial supporting role because many unstable nuclei created in reactors decay by beta emission. Beta decay changes a neutron into a proton or vice versa, helping determine how reactor fuel and fission products evolve over time. This affects reactor control, decay heat, and the long-term behavior of spent fuel. The study of these processes is part of nuclear engineering and radiation physics, not only particle physics. Understanding weak decays is essential for safe reactor design and waste management.