Yes, they are fast nuclear reactors
It is a nuclear reactor without reflector, consisting only from fuel and moderator.
The moderator is used to slow down the neutrons present in the core of the reactor. Normally the neutrons produced as the nuclear fuel (e.g. uranium) is fissioned are travelling too fast to produce a sustained chain reaction. Some examples of moderators are cadmium, heavy water and graphite.
The primary role of graphite moderator is to moderate the neutron energies however it may also capture some heat during reactor operation.
The core of the reactor contains the nuclear fuel. Having a moderator in place within the core ensures that the nuclear fuel is processed at an accurate time duration. This can prevent serious problems from occurring within the entire nuclear reactor.
Shielding is used to prevent the escape of neutrons from a reactor. A moderator is used in the reactor to undergo collisions with a neutron. The neutrons produced in fission collide with the molecules of the moderator, imparting their kinetic energy on them. This generates heat in the reactor. (Temperature is the measure of the average random molecular kinetic energy of a substance).
No, a breeder nuclear reactor does not typically use a moderator. Breeder reactors are designed to produce more fissile material than they consume by using fast neutrons to convert non-fissile isotopes into fissile ones without slowing down the neutrons.
A moderator is necessary in a reactor to slow down fast-moving neutrons produced during nuclear fission. This helps control the rate of reaction and enables more neutrons to be captured by other atoms, sustaining the chain reaction. Additionally, the moderator helps manage the temperature and pressure within the reactor to prevent overheating and maintain stability.
The fission reactor is composed of:Nuclear fuel,reactor coolants,neutron moderator (optional)control elementsshieldingmeasurement instrumentssupporting structures... etc
moderator, coolant
This is done in order to limit corrosion of the internal reactor components
Moderator is not used in case of fast breeder reactor because there is no need to slow down neutron energy. Nuclear fission takes place at high energy of neutrons.
Moderators are not used in a breeder reactor because their primary purpose is to slow down neutrons to increase the likelihood of fission events in a thermal reactor. In a breeder reactor, fast neutrons are required to convert non-fissile uranium-238 into fissile plutonium-239, so using a moderator would hinder this process.