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What is the quantity of fissionable material called that CANNOT sustain a nuclear reaction?
Subcritical mass is the quantity of fissionable material that cannot sustain a nuclear reaction. When the amount of fissionable material is below the critical mass required to sustain a chain reaction, it is considered subcritical.
Fissionable material that cannot sustain nuclear reaction?
Fissionable material that cannot sustain a nuclear reaction on its own is called fissile material. Examples include uranium-238 and thorium-232. These materials can undergo fission when bombarded with neutrons but require additional enrichment or a moderator to sustain a chain reaction.
Describe a characteristic of a fissionable substance that is essential for a chain reaction to sustain itself?
Firstly it must be able to capture neutrons which then have a high probability of causing its nuclei to undergo fission or splitting, and the fissions must produce enough further neutrons so that for every fission that occurs, another one will follow.
Is it true or false that the only isotopes that can be used as fuel in a nuclear power plant are those in which a chain reaction can occur?
True, only fissionable isotopes that produce enough excess neutrons to sustain a chain reaction can be used directly as fuel.However fertile isotopes that capture neutrons and then transmute to fissionable isotopes can be used indirectly as fuel through a process called breeding.
What is the term that is used to describe a key factor required to start a fission reaction?
The term is "critical mass." It refers to the minimum amount of fissionable material, such as uranium or plutonium, required to sustain a chain reaction in a nuclear reactor or bomb.
A nuclear chain reaction occurs when excess collide with other nuclei?
Actually, a nuclear chain reaction occurs when a fissionable material, such as uranium-235 or plutonium-239, undergoes a nuclear reaction that releases additional neutrons. These newly released neutrons can then collide with other fissionable nuclei, continuing the chain reaction and releasing a significant amount of energy in the process.
What is the amount of fissionable material required to continue a reaction at a constant rate?
The amount of fissionable material required to sustain a nuclear reaction at a constant rate is determined by the material's critical mass. The critical mass is the minimum amount of fissionable material needed to sustain a chain reaction, and it varies depending on the material and the reactor design. By controlling factors such as neutron moderation and absorption, reactor operators can adjust the critical mass to maintain a steady reaction rate.
Describe a characteristic of a fissionable substance that is essential for a chain-reaction to sustain itself?
The fission process is sustained by neutrons. A neutron entering a nucleus and causing fission must be replaced in order to cause the next fission, and so on. So the fissionable substance must emit more neutrons when fission occurs, and enough of them so that despite some being absorbed by the moderator and some leaking from the reactor boundary, there is still enough to maintain the chain reaction. Uranium 235 emits on average about 2.5 neutrons per fission (you might say what is half a neutron, but this is explained by the fact that fissions have a range of possible results, with different numbers of neutrons emitted, and the average is 2.5).
Why does a chain reaction not occur in uranium mines?
Mainly because only about 0.7% of uranium is the isotope uranium-235, which is easily fissionable. It is believed that in Earth's remote past, there were such chain reactions - natural reactors - at a time when the percentage of U-235 was higher.
What is the amount of fissionable material that must be present in order for a nuclear reaction to take place called?
The critical mass. With an amount of U-235 or Pu-239, the smallest critical mass will be a sphere. For a nuclear reactor, it will be the minimum number of fuel assemblies loaded to produce a chain reaction.
What is the difference between 'fissile material' and 'fissionable material'?
Fissile material refers to substances that can sustain a nuclear chain reaction upon absorbing a slow neutron, such as uranium-235 and plutonium-239. In contrast, fissionable material includes any substance capable of undergoing fission, which can occur with either slow or fast neutrons; this category encompasses both fissile materials and those that require fast neutrons to undergo fission, like uranium-238. Thus, all fissile materials are fissionable, but not all fissionable materials are fissile.
Is a chain reaction possible in a substance that emit no neutrons when it fission?
No, a chain reaction is not possible in a substance that emits no neutrons when it undergoes fission. Neutrons are required to sustain a chain reaction by triggering the fission of other atoms in the substance. Without neutron production, the fission process cannot continue to release energy and sustain the chain reaction.
