Neutronläckage

Neutronläckage refers to the escape of neutrons from a nuclear reactor core or a nuclear weapon. Neutrons are critical for sustaining nuclear chain reactions. In a reactor, neutrons produced by fission must be moderated and then interact with fissile material to cause further fissions. If too many neutrons escape the core, the chain reaction may become subcritical and cease, leading to a shutdown of the reactor. Conversely, in a nuclear weapon, neutron leakage is undesirable as it reduces the efficiency of the explosion by preventing neutrons from causing further fissions in the fissile material.

To minimize neutron leakage in reactors, neutron reflectors are often employed. These materials, typically made of substances like graphite, beryllium, or heavy water, surround the reactor core. They are designed to scatter neutrons that are moving outwards back into the core, increasing the probability of them causing further fissions. The size and geometry of the reactor core also play a significant role in neutron leakage; larger cores generally have less surface area relative to their volume, thus reducing leakage.

In nuclear weapons, neutron leakage is also a concern, but the primary goal is to achieve a rapid and efficient chain reaction before the fissile material can disassemble due to the explosion. Neutron reflectors are also used in weapons to reflect escaping neutrons back into the core, enhancing the yield. The design of nuclear weapons aims to achieve supercriticality very rapidly, which inherently involves managing neutron leakage to maximize the number of fissions in a short period. The amount of neutron leakage is a key parameter in reactor physics and nuclear weapon design.