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How is the rate of the fission in a nuclear reactor controlled?
By the control rods and by the moderator.
How is the rate of a fission reaction controlled within a nuclear reactor?
Using control rods that obsorb neutrons, and can be gradualy raised or lowered into the core. In emergencies, "neutron poisons" are used, which almost instantly stop most fission within the core.
When fission is not controlled how is it used?
Reactions that involve nuclei, called nuclear reactions, result in a tremendous amount of energy. Two types are fission and fusion.
What is meant by chain reaction in nuclear reactor?
Basically a chain reaction (nuclear or chemical) is a self sustaining auto-catalytic reaction.In a nuclear reactor it is a neutron chain reaction, where each neutron released in every fission event can trigger another fission event. In a nuclear reactor the excess neutrons must be disposed of, which is the purpose of the control rods so that the reaction can be kept at some desired constant rate.
The differences between nuclear reactors and nuclear bombs include what?
Nuclear reactors produce exactly one additional fission for each fission reaction while nuclear bombs don't Nuclear bombs are runaway fission reactions and reactors aren't (APEX)
How can nuclear fission be slowed?
Yes, by introducing a neutron absorber such as boron. In a nuclear reactor this is done by inserting the control rods
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 could you increase the rate of fission reactions?
Fission does not respond to changes in temperature and pressure like chemical reactions do. In a nuclear reactor, the fission chain reaction can be sped up by removing rods of cadmium, which absorb neutrons. These are in place to prevent the reaction from occurring too quickly. Remove them, and the chain reaction may proceed out of control.
what is fission chain reaction how can it be controlled?
Fission chain reactions occur because of interactions between neutrons and fissile isotopes (such as 235U). The chain reaction requires both the release of neutrons from fissile isotopes undergoing nuclear fission and the subsequent absorption of some of these neutrons in fissile isotopes. When an atom undergoes nuclear fission, a few neutrons (the exact number depends on several factors) are ejected from the reaction. These free neutrons will then interact with the surrounding medium, and if more fissile fuel is present, some may be absorbed and cause more fissions. Thus, the cycle repeats to give a reaction that is self-sustaining. Nuclear power plants operate by precisely controlling the rate at which nuclear reactions occur, and that control is maintained through the use of several redundant layers of safety measures. Moreover, the materials in a nuclear reactor core and the uranium enrichment level make a nuclear explosion impossible, even if all safety measures failed. On the other hand, nuclear weapons are specifically engineered to produce a reaction that is so fast and intense it cannot be controlled after it has started. When properly designed, this uncontrolled reaction can lead to an explosive energy release
What is the other name for uncontrolled nuclear fission?
The term "fast critical" means super criticality to the point where the rate of neutron increase is not limited by delayed neutrons as in a normal controlled reactor. This would be true of a nuclear weapon.
What is a neutron reaction?
You are probably referring to nuclear fission. this occurs in some isotopes of heavy elements, most notably Uranium 235 and Plutonium 239. The fission of the nucleus releases energy, and forms two fragments which are nuclei of two lighter elements. The reaction can be controlled to occur at a steady rate thus releasing a steady supply of thermal energy.
How does nuclear fission work?
The breakup of large nuclei into two nearly equal fragments is called nuclear fission. It sometimes produces neutrons, protons or other nuclei. This is important in nuclear reactor and bombs, where neutrons emitted from one fission event cause other nuclei to fission, releasing more neutrons and so causing chain reaction. If this chain is controlled then you have a nuclear reactor whose heat can be used to boil water and generate electricity. If the chain is uncontrolled it causes a nuclear explosion.
