Neutrontartalék

Neutrontartalék refers to the surplus of neutrons available in a nuclear reactor core beyond what is strictly necessary to sustain a chain reaction at a given power level. This excess neutron population is essential for controlling the reactor's operation and for managing its lifecycle.

The neutron population in a reactor is influenced by various factors, including neutron generation, leakage, absorption by fuel, absorption by control rods and structural materials, and absorption by fission products. A critical reactor is one where the neutron population remains constant, leading to a steady power output. To achieve this steady state, the rate of neutron production must balance the rate of neutron loss.

The neutron reserve allows for adjustments in reactivity. For example, inserting control rods absorbs neutrons, reducing the neutron population and thus lowering the reactor power or shutting it down. Conversely, withdrawing control rods decreases neutron absorption, increasing the neutron population and raising the power. This flexibility is crucial for startup, shutdown, and load-following operations.

Furthermore, the neutron reserve is utilized for reactor startup. When starting up a reactor from a shutdown state, excess reactivity is deliberately introduced, typically by withdrawing control rods, to increase the neutron population and bring the reactor to the desired power level. Over time, as fuel is consumed and fission products accumulate, the neutron economy changes, and the neutron reserve naturally diminishes. This depletion is a factor in determining the operational lifespan of reactor fuel.