0
U-235 can fission by absorbing fast or slow neutrons, but it has a much larger cross section for slow ones, that is it absorbs slow neutrons much more readily than fast ones. This enables moderated reactors to operate with low enriched (5% or less) or even natural uranium, whilst fast reactors must have much more highly enriched uranium, ie with more U-235. The ultimate is the nuclear bomb, where almost pure U-235 will fission entirely with fast neutrons, if enough of it is suddenly put together.
Wiki User
∙ 14y ago
Add your answer:
Earn +20 pts
Is moderation of neutrons always used to slow nuclear fission?
No, moderation of neutrons is not always used to slow nuclear fission. In some types of nuclear reactors, such as fast breeder reactors, fast neutrons are intentionally not moderated to slow down the fission process. These reactors operate using fast neutrons to sustain a chain reaction. However, in most commercial nuclear reactors, moderation of neutrons is employed to slow down the fission process and maintain a controlled chain reaction.
What is the effect of slow neutron on nuclear reactions?
Slow neutrons are more likely to be absorbed by nuclei in nuclear reactions compared to fast neutrons. This absorption increases the probability of inducing fission in heavy nuclei or capturing the neutron to form a new isotope. Slow neutrons are commonly used in nuclear reactors to sustain and control nuclear fission reactions.
Why moderator is not used in case of fast breeder reactor?
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.
What causes fission?
Fission is caused by the splitting of a heavy atomic nucleus into two or more lighter nuclei, releasing a large amount of energy in the form of gamma rays and nuclear particles. This process is triggered by the absorption of a neutron by the nucleus of a heavy atom, such as uranium or plutonium.
Why fission cannot take place with fast neutron?
In order to cause an atomic nucleus to become unstable so that it will undergo fission, you have to add a neutron. If a slow neutron collides with an atomic nucleus, it will be absorbed into the nucleus and become part of it. The nuclear attraction of the nucleus is strong enough to grab a slow neutron. But a fast neutron cannot be captured because it has too much kinetic energy. The attraction of the nucleus is not enough to stop the motion of a fast neutron. Even if a fast neutron makes a direct hit on an atomic nucleus, it is just going to bounce off.
Why you use slow neutrons instead of fast neutrons in nuclear reaction?
in reacter U-235 fission is due to slow neutrons because in reacter the probability of fission from fast neutron is approximatly zero.
Is moderation of neutrons always used to slow nuclear fission?
No, moderation of neutrons is not always used to slow nuclear fission. In some types of nuclear reactors, such as fast breeder reactors, fast neutrons are intentionally not moderated to slow down the fission process. These reactors operate using fast neutrons to sustain a chain reaction. However, in most commercial nuclear reactors, moderation of neutrons is employed to slow down the fission process and maintain a controlled chain reaction.
Is uranium 238 a slow or fast neutron absorber?
Uranium 238 is considered a slow neutron absorber because it does not readily absorb fast neutrons. It can capture slow neutrons and transform into plutonium 239 through a nuclear reaction called neutron capture.
Why not fast neutron use in fission?
Fast neutrons are less efficient in causing fission reactions compared to thermal neutrons because they have higher energy and tend to bounce off nuclei rather than being absorbed. This makes it harder to sustain a chain reaction in a reactor. Additionally, fast neutrons produce more radioactive waste and have higher chances of causing undesirable side reactions in the reactor.
What are the Specifications for uranium used in nuclear power plants?
The uranium is in the form of uranium dioxide, UO2, which is produced in small cylinders and assembled inside a zircaloy sealed sheath. The individual zircaloy tubes filled with uranium are then made up into a fuel assembly, the number in each assembly varies from one design to another. The uranium itself is enriched to about 4 percent U235. Natural uranium has about 0.7 percent U235, which is the isotope required for slow neutron fission.
What is the effect of slow neutron on nuclear reactions?
Slow neutrons are more likely to be absorbed by nuclei in nuclear reactions compared to fast neutrons. This absorption increases the probability of inducing fission in heavy nuclei or capturing the neutron to form a new isotope. Slow neutrons are commonly used in nuclear reactors to sustain and control nuclear fission reactions.
Why moderator is not used in case of fast breeder reactor?
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.
Is plodded a fast or a slow?
not a fast but slow
The form of lullys french overture was?
slow-fast-slow (Apex)
If wood undergoes a slow smothered combustion what is left?
Charcoal
Why fission cannot take place with fast neutron?
In order to cause an atomic nucleus to become unstable so that it will undergo fission, you have to add a neutron. If a slow neutron collides with an atomic nucleus, it will be absorbed into the nucleus and become part of it. The nuclear attraction of the nucleus is strong enough to grab a slow neutron. But a fast neutron cannot be captured because it has too much kinetic energy. The attraction of the nucleus is not enough to stop the motion of a fast neutron. Even if a fast neutron makes a direct hit on an atomic nucleus, it is just going to bounce off.
What causes fission?
Fission is caused by the splitting of a heavy atomic nucleus into two or more lighter nuclei, releasing a large amount of energy in the form of gamma rays and nuclear particles. This process is triggered by the absorption of a neutron by the nucleus of a heavy atom, such as uranium or plutonium.
