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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.
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Why is it that uranium ore does not spontaneously undergo a chain reaction?
Uranium ore contains only a small percentage of uranium for one thing, but also natural uranium contains only 0.7 percent U235. Even pure natural uranium will not cause a chain reaction unless it is surrounded by a moderator such as pure graphite or heavy water. Ordinary water will not allow this to happen.
For a chain reaction occur each fission must produce at least ____more fission reaction?
its 1 i think
Why does a chain reaction occur when uranium 235 undergoes fission?
Neutrons do this. When 235U undergoes fission, the result is the production of two daughter atoms, each very roughly half the mass of the original atom, a number of neutrons, and heat. The neutrons then can collide with other fissile or fissionable atoms causing them to undergo fission much more quickly than they otherwise would.
What part of the nuclear powerplant does the chain reaction occur?
In the reactor core, which is the volume filled with the fuel assemblies
When does the reaction force occur?
At the same time
How the mining of uranium occur?
Extraction of uranium:- extraction from underground mines- open pit mines- leaching
Where does uranium occur in South Africa?
South Africa has uranium mines at Bauteng, Brakpan, Krugersdorp..
Is a chain reaction more likely to occur in two separate pieces of uranium-235 or in the same two pieces stuck together?
Stuck together.
Why is it that uranium ore does not spontaneously undergo a chain reaction?
Uranium ore contains only a small percentage of uranium for one thing, but also natural uranium contains only 0.7 percent U235. Even pure natural uranium will not cause a chain reaction unless it is surrounded by a moderator such as pure graphite or heavy water. Ordinary water will not allow this to happen.
Name the element when uranium captures a fast neutron?
The element is determined by the number of protons. When uranium captures a fast neutron it is still uranium but has an increased atomic mass. Fast neutron capture may encourage a further reaction but it depends on which uranium isotope you start with as to the increase in probability some further reaction will occur and which reaction that might be.
Does fusion reaction occur in an atomic bomb?
They have a starter in a bomb and what this will do is shoot a neutron in the nuclear fuel starting a chain reaction
What condition is not necessary for a chain reaction to occur?
The absence of a bombarding presence of neutrons.
Where nuclear reaction occur?
In the nucleus of the fuel material, such as uranium-235
In what area of the nuclear power plant does the chain reaction occur?
fuel assemblies in the core.
Why can ordinary uranium not be used to fuel a reactor cooled by ordinary water?
Because "ordinary" uranium is mostly 238U, which won't fission and create a chain like its lighter cousin 235U will. When critical mass is achieved with the 235U isotope of uranium, fission will occur spontaneously. Or with a significantly enriched uranium fuel (one where the natural concentration of 235U has been increased a bunch so the fuel has a much higher percentage of this isotope), fission and a chain reaction is also possible. But with just natural uranium, a big pile of it will just sit there. It won't fission and create a chain reaction. Note that 238U is radioactive and decays over time because it is unstable, but it has a long half-life. Also, the fact that it's unstable (radioactive) doesn't mean it's fissile. It isn't.
Minimum mass of material requied for the nuclear chain reaction to occur in a nuclear bomb is called?
The critical mass
For a chain reaction occur each fission must produce at least ____more fission reaction?
its 1 i think
