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they will more likely be absorbed by more atoms in uranium-235
Wiki User
∙ 7y ago
Dilim
Does graphite slow neutrons down?
The neutrons simply collide with graphite atoms and get slowed by impacts. Some get absorbed but not too many, and it is important to have very pure graphite to avoid absorption by other elements in the graphite as impurities.
What is neutron absorption?
Neutron absorption is the process wherein an atomic nucleus will absorb a neutron. Many different atomic nuclei will do this, and different nuclei will present a larger of smaller target for the neutron, as you might have guessed. This is the neutron absorption cross section for the material, and it varies as the material does and as the kinetic energy of the neutron does, as well. You may have figured out that there are many different resulting products or outcomes that can be seen from neutron absorption. It is neutron absorption that powers up a chain reaction, so let's look at that aspect of this phenomenon. In a nuclear reactor, some spontaneous fissions will release neutrons, and these neutrons will, if the control rods are pulled out sufficiently, begin a chain reaction. The nuclear fuel, usually either uranium or plutonium, will absorb a neutron (after some slowing down of that neutron), and they'll fission as a result. These fissions will release more neutrons, which will be absorbed and will create more fissions, which will release more neutrons, etc. A neutron released from a fission event will have a high kinetic energy; it will be moving very quickly. It might be absorbed, but will have a higher probability of being absorbed if it is slowed down, or thermalized. The moderator in a reactor, usually water, does this slowing down of the neutrons. The slower neutrons have a much higher probability of being absorbed and continuing the chain. Fission by neutron absorption is the mechanism by which a nuclear chain reaction is maintained in a nuclear reactor.
What can protons and neutrons be subdivided into by colliding them?
A proton can be divided into 2 Ups and a Down quark, and a neutron into 2 Downs and an Up quark. In general the quark is the elementary particle from which protons and neutron are formed.
How can uranium 235 create electricity?
In physics and nuclear fission. A neutron is fired at a uranium-235 atom which then splits into daughter nuclei, the daughter nuclei releases more netrons which splits more and more uranium-235 atoms. This is called a chain reaction. The chain reaction releases heat which can then be used to turn a turbine which turns a generator and generates electricity. A moderator can be used to slow down neutrons and the chain reaction. When the neutrons are slowed down to the right speed, control/fuel rods absorbs the neutrons which slows down the reaction rate. This makes nuclear fission controllable, unlike nuclear fusion which is uncontrollable. Hope this helps
What part of an atom does not consist of a quark?
The protons and neutrons (which in the atom is in the nuclues) are made from quarks. The proton is built from two up-quarks and one down-quark and the neutron is built from one up-quark and two down-quarks.
What is the slowing down of neutrons to increase the probability of their absorption by the Atoms in uranium called?
neutron moderation
What is the slowing down of neutrons to increase the probability of their absorption by atoms in uranium called?
neutron moderation
What is the slowing down of neutrons to increase their probability of absorption by the atoms in uranium 235 called?
Neutron moderation
What defines the process in a nuclear reactor that reduces the speed of neutrons so they can be captured by the reactor fuel in order to continue the chain reaction?
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.
A neutron is an unstable particle outside a nucleus but to start nuclear fission requires the slowing down of a neutron. How is nuclear fusion carried out in the case of uranium?
The neutrons released from Uranium are fast neutrons. In a reactor they are slowed down by a moderator. The moderator could be water, heavy water, graphite, among others. When the neutron is slowed down, it is more likely to create fission.This is what happens with the U-235. The U-238 does not fission, but it does transmute through a series of neutron absorption and beta decay etc. into plutonium which does fission also.
What does thermal indicates in thermal neutrons?
A thermal neutron has much less energy / velocity than a fast neutron. As a result, it has a much larger neutron absorption cross section, making it easier for it to be absorbed by certain nuclei and subsequently initiate fission. The fast neutrons that result from fission are slowed down, i.e. moderated, usually by water, in order to become thermal neutrons and to sustain the fission chain reaction.
Does graphite slow neutrons down?
The neutrons simply collide with graphite atoms and get slowed by impacts. Some get absorbed but not too many, and it is important to have very pure graphite to avoid absorption by other elements in the graphite as impurities.
Why must neutrons in a chain reaction be controlled?
Neutrons in a nuclear fission chain reaction must be controlled for two reasons... First, they must be moderated, or "slowed down", to exactly the right level of energy required to sustain the reaction. This is because, initially, the neutrons are too fast to sustain the fission reaction. They must be slowed down, but not too much, otherwise the reaction will stop. Second, they must be controlled. You want the reaction to proceed at an orderly pace, at a constant rate. To do this, you need, on a statistical average, exactly one neutron to go on to fission one atom to produce one parcel of binding energy release and one neutron, to repeat without multiplying or dividing. This is what we call KEffective = 1, where the rate of reaction does not change. Moderation and control. In tight balance. Easily upset. Fortunately, when upset, the tendency is to shutdown. That is engineering safety.
How can the rate of reaction be slowed down in a nuclear fission reactor?
By inserting the control rods which absorb neutrons using boron, cadmium, or other material with a large neutron capture crosssection. If the reactor should begin to run out of control the SCRAM system will suddenly insert large amounts of neutron absorbing material, instantly stopping the neutron chain reaction.
What is neutron absorption?
Neutron absorption is the process wherein an atomic nucleus will absorb a neutron. Many different atomic nuclei will do this, and different nuclei will present a larger of smaller target for the neutron, as you might have guessed. This is the neutron absorption cross section for the material, and it varies as the material does and as the kinetic energy of the neutron does, as well. You may have figured out that there are many different resulting products or outcomes that can be seen from neutron absorption. It is neutron absorption that powers up a chain reaction, so let's look at that aspect of this phenomenon. In a nuclear reactor, some spontaneous fissions will release neutrons, and these neutrons will, if the control rods are pulled out sufficiently, begin a chain reaction. The nuclear fuel, usually either uranium or plutonium, will absorb a neutron (after some slowing down of that neutron), and they'll fission as a result. These fissions will release more neutrons, which will be absorbed and will create more fissions, which will release more neutrons, etc. A neutron released from a fission event will have a high kinetic energy; it will be moving very quickly. It might be absorbed, but will have a higher probability of being absorbed if it is slowed down, or thermalized. The moderator in a reactor, usually water, does this slowing down of the neutrons. The slower neutrons have a much higher probability of being absorbed and continuing the chain. Fission by neutron absorption is the mechanism by which a nuclear chain reaction is maintained in a nuclear reactor.
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.
How many neutrons are produced during a typical uranium fission reaction and what is the role of these neutrons in a nuclear chain reaction?
A typical uranium fission event produces 2 to 3 neutrons. These neutrons are moderated (slowed down) and go on to initiate the fission of more uranium. On average, in a controlled reaction that is maintained at normal criticality (KEffective = 1), each fission creates exactly one neutron that is used to produce another fission.
