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What is the amount of fissionable material required to continue a reaction at a constant rate?
Wiki User
∙ 12y ago
At less than critical mass, there are fewer "targets" for neutrons to strike, fission, and release more neutrons. As a result, the reaction dies out.
Wiki User
∙ 12y ago
Wiki User
∙ 6y agoKnown as the critical mass
Wiki User
∙ 12y agoThe critical mass
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∙ 12y ago"critical mass"
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∙ 12y agoCritical mass
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∙ 11y agocritical mass
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∙ 13y ago15 grams
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The smallest amount of a fissionable material that will give a self-sustaining chain reactions is called the?
The smallest amount of a fissionable material that will produce a self-sustaining chain reaction is called the critical mass. This mass of affected by geometry and other factors such as temperature, pressure, and moderator.
Atoms that naturally undergo nuclear fissions are called?
These are called fissile or fissionable. Fissile isotopes undergo fission, producing sufficient neutrons of sufficient power that a chain reaction can happen, if there is enough of the isotope to support it. The mass sufficient to support a chain reaction is called critical. Atoms of fissionable isotopes will undergo fission when a sufficiently energetic neutron collides with them, but the neutrons they emit when they divide are either insufficient in number or insufficient in energy to sustain an chain reaction. There is a third type of material that can undergo fission, called fertile, which is isotopes that can be caused to capture neutrons, changing into fissile or fissionable isotopes, so the fission does not happen to atoms of the fertile material directly, but to the atoms of the isotopes they become.
Fission reactions can be run continously to generate electric power commercially because?
A steady state chain fission reaction is set up in the reactor, when just enough of the neutrons released in each fission is captured by other fissionable nuclei to keep the number of fissions occurring every second at a constant level. Thus the reactor power is held at a steady level. The reactor in terms of nuclear properties is then said to be "critical". As operation proceeds the U-235 gets used up, but this is counteracted to some extent by the production of plutonium from U-238, the plutonium also being fissionable. Eventually the reactor runs out of fissionable material and has to be refuelled, but this can be only at intervals of two years or so, between these refuelling outages the power output can be maintained continously.
What is the k in the rate law equation?
A rate constant
Why do uranium ore have be enriched?
Because only the isotope 235U is fissionable with thermal neutrons and also is good for nuclear weapons. This is because normal uranium in the Earth is 0.7 % 235U and 99.3 % 238U. The 235U needs to be enriched to 4 % or greater in order to be effective as a fissile material (fission with neutrons producing fission and more neutrons that can continue the reaction) reaction. Power plants run around 4 % to 5 %; but CANDU type reactors work with natural uranium. Weapons run +99 %. Small high capacity reactors, such as on a submarine, run around 20 %.
Fissionable material that cannot sustain nuclear reaction?
Sub Critical
What is the quantity of fissionable material called that CANNOT sustain a nuclear reaction?
Sub Critical
What is required for a chain reaction to start?
Critical Mass is that minimum amount of fissionable material needed to maintain a chain reaction
The smallest amount of a fissionable material that will give a self-sustaining chain reactions is called the?
The smallest amount of a fissionable material that will produce a self-sustaining chain reaction is called the critical mass. This mass of affected by geometry and other factors such as temperature, pressure, and moderator.
Why does a chain reaction die out in small pieces of fissionable fuel but not in large pieces?
Because in small samples the probability of a neutron escaping the sample without inducing another fission is bigger. Actually, what matters is the mass of the sample, especially if this mass exceeds the critical mass. Thus, the chain reaction in a smaller sample with sufficiently higher density of fissionable material might not die out, while it dies out in a larger sample with albeit a sufficiently smaller density of fissionable material.
How to make nuclear bomb-?
To make a nuclear bomb, you need the fissionable material such as a Plutonium239 isotope, an explosive to start the nuclear chain reaction, a detonator, and a pusher.
What is meant by supercritical andhow dose it relate to making a nuclear bomb?
subcritical - a mass or arrangement of fissionable or fissile material unable to sustain a neutron chain reaction. It can provide a fixed amount of neutron multiplication from a neutron source, but after removal of the neutron source the chain reaction rate drops exponentially.critical - a mass or arrangement of fissionable or fissile material capable of sustaining a constant neutron chain reaction. No increase or decrease. (Nuclear reactors operate at critical)supercritical - a mass or arrangement of fissionable or fissile material capable of not only sustaining a neutron chain reaction, but once initiated the chain reaction rate rises exponentially. (Nuclear fission bombs explode when made supercritical)A nuclear fission bomb must have 2 of these states: subcritical (so that it can't explode until desired) and supercritical (so that it explodes with an effective yield). This requires a rapid "assembly" system using conventional explosives to rearrange the fissile material from subcritical to supercritical in about 1ms. A neutron source starts the chain reaction and the explosion completes in about 1 microsecond.
What does the value of the equilibrium constant indicate?
When a chemical reaction reach the equilibrium she can not continue spontaneously.
Atoms that naturally undergo nuclear fissions are called?
These are called fissile or fissionable. Fissile isotopes undergo fission, producing sufficient neutrons of sufficient power that a chain reaction can happen, if there is enough of the isotope to support it. The mass sufficient to support a chain reaction is called critical. Atoms of fissionable isotopes will undergo fission when a sufficiently energetic neutron collides with them, but the neutrons they emit when they divide are either insufficient in number or insufficient in energy to sustain an chain reaction. There is a third type of material that can undergo fission, called fertile, which is isotopes that can be caused to capture neutrons, changing into fissile or fissionable isotopes, so the fission does not happen to atoms of the fertile material directly, but to the atoms of the isotopes they become.
Critical mass is the of material required to produce a chain reaction?
minimum amount
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 material used to decrease the rate of reaction is?
Water for one. If a reaction is diluted, the components of the reaction are less likely to contact one another. This will mean that they will be also less likely to continue a reaction.
