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There is no single quantity, it depends on many factors some are:
- enrichment level
- presence/absence of moderator
- type of moderator
- presence/absence of reflector
- thickness of reflector
- type of reflector
- presence/absence of absorber
- type of absorber
- has the uranium been compressed beyond standard density
- etc.
For some general order of magnitude values:
- in a typical water moderated reactor, the critical mass of the 3% enriched uranium is usually several tons
- in a typical atomic bomb with a depleted uranium tamper/reflector, the critical mass of the 93.5% enriched uranium is 15 to 20 kg depending mostly on the thickness of the tamper/reflector
What else can I help you with?
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.
Does a critical mass of uranium require enriched uranium?
Yes, a critical mass of uranium typically requires enriched uranium. Enriched uranium has a higher concentration of the fissile isotope uranium-235, which is necessary for sustaining a nuclear chain reaction in a reactor or weapon. Unenriched uranium, which is mostly uranium-238, requires a larger critical mass to achieve a sustained chain reaction.
What does uranium and plutonium do inside a bomb?
The critical mass of plutonium is lower, plutonium is not so expensive as highly enriched uranium, the technology to obtain plutonium is more simple than the isotopic separa-tion of uranium, etc.
Why can't uranium ore explode in the ground?
No critical mass underground; but as a curiosity read about the Oklo phenomenon.
Does a critical mass require enriched uranium?
No, a critical mass does not require enriched uranium. A critical mass is the minimum amount of fissile material needed to sustain a nuclear chain reaction. While enriched uranium is a commonly used fissile material for nuclear reactions, other materials such as plutonium can also achieve criticality.
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.
Does a critical mass of uranium require enriched uranium?
Yes, a critical mass of uranium typically requires enriched uranium. Enriched uranium has a higher concentration of the fissile isotope uranium-235, which is necessary for sustaining a nuclear chain reaction in a reactor or weapon. Unenriched uranium, which is mostly uranium-238, requires a larger critical mass to achieve a sustained chain reaction.
What is the critical mass of uranium-238?
Each isotope has a different critical mass. U235 is used because the mass needed to cause a reaction is smaller than almost all other isotopes. This critical mass is calculated as( 3.001 x 9.987 to the 11th power) Divided by the weight of one nuclei X 2.5675 (x 10 to the 24th power) divided by mass. This equals 7.702 X 10 to the 13th power divided by mass. You can tell by this calculation that critical mass for u235 is very low at about 1.3 kg. Best regards, Bruce
What does uranium and plutonium do inside a bomb?
The critical mass of plutonium is lower, plutonium is not so expensive as highly enriched uranium, the technology to obtain plutonium is more simple than the isotopic separa-tion of uranium, etc.
Why can't uranium ore explode in the ground?
No critical mass underground; but as a curiosity read about the Oklo phenomenon.
Used as an explosive ingredient in nuclear weapons?
Uranium-235 is used as the fissile material in nuclear weapons. When a uranium-235 atom undergoes fission, it releases a large amount of energy, which can create a nuclear explosion. The critical mass required for a nuclear chain reaction to occur is achieved by compressing uranium-235 using conventional explosives.
Does a critical mass require enriched uranium?
No, a critical mass does not require enriched uranium. A critical mass is the minimum amount of fissile material needed to sustain a nuclear chain reaction. While enriched uranium is a commonly used fissile material for nuclear reactions, other materials such as plutonium can also achieve criticality.
When uranium will blast?
Uranium itself does not blast or explode on its own. It can undergo a process called nuclear fission in a controlled environment such as a nuclear reactor, leading to a highly energetic chain reaction. Uncontrolled fission could result in a nuclear explosion.
What is the differences of plutonium and uranium?
Uranium is a natural chemical element, plutonium is an artificial element (but note that plutonium exist also naturally in the earth crust in extremely low concentrations). Uranium has the atomic number 92 and plutonium 94. The critical mass of uranium is greater than the critical mass of plutonium. The melting and boiling points of U and Pu are different. Uranium has an orthorombic crystalline structure; the structure of plutonium is monoclinic. And many other physical and chemical properties are different.
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.
Critical mass is the of material required to produce a chain reaction?
minimum amount
You cannot make a bomb from uranium ore as it occurs in nature because it it?
Uranium ore as it occurs in nature is mostly composed of uranium-238, which is not fissile. This means it cannot sustain a chain reaction required for a bomb. Special enrichment procedures are necessary to increase the concentration of fissile uranium-235 for bomb-making.
