It is the moderator in a nuclear reactor that is used to slow neutrons down in a thermonuclear reactor. The moderator, which is often water, slows the neutrons by providing a "target" for the neutron to slam into. The resulting collision (called a scattering event) will allow the moderator to absorb some of the kinetic energy from the neutron, and that neutron will come away at a lower velocity than it did coming in. The hydrogen in water (it's H2O) has, in most cases, a single proton in its nucleus. As the proton in a hydrogen nucleus has approximately the same mass as a neutron, there will be, in general, a larger amount of energy stripped from the neutron in a given scattering event. (If you consider, say, a scattering even between a Golf ball and a Bowling ball, the golf ball won't lose much energy to the bowling ball. But if the golf ball undergoes scattering with another golf ball, there is a "better" result and more slowing of the neutron.)
In addition to the use of water (both light and heavy water) as a moderator, we also find that graphite (an allotrope of carbon -- pencil lead) and liquid metals are also used as moderators. The same idea applies, and the moderator, whatever one it is, provides a target for higher energy neutrons to slam into. The result of the scattering events is that the neutrons are slowed in the process.
Heavy water can be used in a nuclear reactor to moderate the speed of neutrons, making it easier for uranium-238 to absorb a neutron and become plutonium-239. This process is known as breeding plutonium in a reactor and is one method of producing plutonium for nuclear weapons or fuel.
You did not provide the list of "the following". However, the answer to the question is moderation. Moderation is the process whereby the neutron is slowed down in order to facilitate its subsequent capture by the nuclei of the fuel.
Boron and/or Cadmium control rods. They are inserted into the core to slow the reaction and withdrawn from the core to speed up the reaction. Both elements have a very high neutron capture crosssection, the more in the core the more excess neutrons they remove from the chain reaction.
No, the function of the control rods is to absorb surplus neutrons so that the chain reaction proceeds at a steady rate, and to compensate for the reducing reactivity of the reactor as the fuel is burned up over the refuelling cycle. They also have a very important safety function in shutting down the reactor fully when required, by inserting them fully, thus preventing any chain reaction from starting.
The material used to slow down high-speed neutrons in a reactor is called the moderator. The moderator in a pressurized water reactor is the water, which is the main coolant. Collisions between the neutron and hydrogen nuclei (protons) slow the neutron down (thermalizing it) and increasing the probability that it will be absorbed by another fissionable atom. That makes the chain go, it maintains the chain reaction. Slowing down neutrons does NOTslow down the process of nuclear fission. If anything, it maintains it or speeds it up because slower moving neutrons have a higher probability of being absorbed and continuing or building the chain reaction. A link is provided.
Heavy water can be used in a nuclear reactor to moderate the speed of neutrons, making it easier for uranium-238 to absorb a neutron and become plutonium-239. This process is known as breeding plutonium in a reactor and is one method of producing plutonium for nuclear weapons or fuel.
You did not provide the list of "the following". However, the answer to the question is moderation. Moderation is the process whereby the neutron is slowed down in order to facilitate its subsequent capture by the nuclei of the fuel.
Control rods need to contain material that is a strong absorber of neutrons, so that rapid shutdown can be achieved when necessary. Two such materials are Cadmium and Boron. Both have been used in different types of reactor. The elements may be used as alloys or as chemical compounds, and will be encased in stainless steel to avoid corrosion in the reactor.
Boron and/or Cadmium control rods. They are inserted into the core to slow the reaction and withdrawn from the core to speed up the reaction. Both elements have a very high neutron capture crosssection, the more in the core the more excess neutrons they remove from the chain reaction.
I think you are talking about nuclear reactors. PWR is a Pressurized Water Reactor, and is the basis for most power generators. BWR is a Boiling Water Reactor. As the water is a major moderating component, controlling the speed and intensity of the nuclear reaction, the steam bubbles in a BWR can present a problem.
Control rods are devices that absorb neutrons and are used to control the speed of a fission reactor. By adjusting the position of the control rods within the reactor core, operators can regulate the rate of the nuclear chain reaction and manage the reactor's power output.
speed
nuclear fuel (thorium, uranium, etc.), electron absorbing rod (krypton, boron, etc.), projectile (which give high speed to electron/proton),
No, the function of the control rods is to absorb surplus neutrons so that the chain reaction proceeds at a steady rate, and to compensate for the reducing reactivity of the reactor as the fuel is burned up over the refuelling cycle. They also have a very important safety function in shutting down the reactor fully when required, by inserting them fully, thus preventing any chain reaction from starting.
The blue glow around the core of a nuclear reactor is called Cherenkov radiation. It occurs when high-energy charged particles, such as electrons, pass through a medium like water at a speed faster than the speed of light in that medium, creating a visible blue glow.
The material used to slow down high-speed neutrons in a reactor is called the moderator. The moderator in a pressurized water reactor is the water, which is the main coolant. Collisions between the neutron and hydrogen nuclei (protons) slow the neutron down (thermalizing it) and increasing the probability that it will be absorbed by another fissionable atom. That makes the chain go, it maintains the chain reaction. Slowing down neutrons does NOTslow down the process of nuclear fission. If anything, it maintains it or speeds it up because slower moving neutrons have a higher probability of being absorbed and continuing or building the chain reaction. A link is provided.
Moderator such as graphite or heavy water would reduce the speed of neutron there by making them as thermal neutrons. Such slow speed neutrons are needed to bring Uranium-235 into fission. Control rods such as Boron carbide or Cadmium are there to abosorb neutrons. So chain reaction of fission is ketp under control.