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2 sie 2023 · A reactor core is typically made up of a couple hundred assemblies, depending on power level. Inside the reactor vessel, the fuel rods are immersed in water which acts as both a coolant and moderator. The moderator helps slow down the neutrons produced by fission to sustain the chain reaction.
The arrangement of particles within uranium-235 is somewhat unstable and the nucleus can disintegrate if it is excited by an outside source. When a U-235 nucleus absorbs an extra neutron, it quickly breaks into two parts. This process is known as fission (see diagram below). Each time a U-235 nucleus splits, it releases two or three neutrons.
In a nuclear reactor, a chain reaction is required to keep the reactor running; When the reactor is producing energy at the required rate, two factors must be controlled: The number of free neutrons in the reactor; The energy of the free neutrons; The main components of a nuclear reactor are: control rods; a moderator; Nuclear reactor diagram
When a fissile nucleus like uranium-235 or plutonium-239 absorbs a neutron, it splits into lighter nuclei, releasing energy, gamma radiation, and free neutrons, which can induce further fission in a self-sustaining chain reaction.
Almost all of the current reactors built to date use thermal neutrons to sustain the chain reaction. These reactors contain neutron moderator that slows neutrons from fission until their kinetic energy is more or less in thermal equilibrium with the atoms (E < 1 eV) in the system. Fast Neutron Reactors.
Thermal reactors primarily rely on thermal neutrons to initiate fission. Thermal reactors include a population of fast, epithermal, and thermal neutrons. Thermal reactors use some relatively low A-value moderator/coolant to slow neutrons down to thermal energy.
Objectives: Understand how Neutron Diffusion explains reactor neutron flux distribution. Understand origin, limitations of Neutron Diffusion from: Boltzmann Transport Equation, Ficke’s Law. Solution of One-Group Neutron Diffusion Equation for: Cubical,
