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the absorb neutrons in controlled nuclear reactions
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A metallic element used in control rods in nuclear power plants is cadmium. This element is used for slowing down the reaction rates for nuclear fission.
They are neutron absorbers, and by raising/lowering they can absorb variable amounts of neutrons. This allows the reactor to be maintained just critical at a steady power, or …power to be raised/lowered, or shutdown completely and safely held down.
Boron-10 is used as control rods in nuclear reactors it absorbs a neutron while it emits an alpha particle what is the resulting product in the control rods?
When B-10 absorbs a neutron, as you say it emits an alpha particle. This contains two protons so the other result is the element with two fewer protons than boron, which is li…thium. So the process is starting with B-10 with 5 protons and 5 neutrons, add 1 neutron, then split into alpha which has two protons and two neutrons, and lithium which has three protons and four neutrons. The control rods have to contain enough boron to last the life of the reactor, unless they are to be replaced, which I don't think is needed. In the AGR gas cooled reactors the rods are made of boron steel alloy, in the light water reactors they are boron carbide.
One or more elements that strongly absorb neutrons, some are: cadmiumboronhafniumetc.
They are made of materials that are good at absorbing neutrons, such as boron. They can be lowered into a nuclear reactor to slow or stop the reaction, for example they are de…signed to drop in automatically if the reactor overheats. They can also be used to speed up the reaction if they are raised. The reason they can slow or speed up a nuclear reaction is because in nuclear reactions a fuel such as uranium or plutonium undergoes nuclear fission. Nuclear fission is where the nucleus of an atom splits. This can happen in spontaneous fission, but in nuclear reactors it happens in neutron-induced fission. In neutron-induced fission, a neutron is fired at an unstable nucleus, such as that of uranium, which is unstable because it has too much energy and mass. The fired neutron adds to the excess of energy and mass, so it makes the nucleus even more unstable. As a result, the nucleus splits releasing energy, and products are two smaller daughter nuclei, gamma radiation, and two or more neutrons. These two or more neutrons can then go off to add excess mass and energy to more nuclei, causing more nuclei to split - this is a chain reaction. Therefore, the control rods work by absorbing these neutrons so that the reaction doesn't go out of control which would result in a nuclear bomb. The idea is that to keep the reaction going at a steady rate, an average of one neutron resulting form a fission should go on to cause another fission.
Absorb surplus neutrons, so that the chain reaction can be kept at a steady level, and also to shut down the reactor fully when required.
Boron is the most commonly used, cadmium can also be used
Usually boron is alloyed with steel, boron is a very good neutron absorber.
There are six reactors at Japan's Fukushima Nuclear Power Plant, and three of them (numbers one, two and three) were operating at the time of the recent earthquake. All of the…se had all their control rods dropped in right after the earthquake struck. This shut down those reactors. The problem is that the operating reactors had been operating at high power for some time before shutdown. And this left a large amount of fission products in the fuel element in the cores of these reactors when they shut down. The fission products of nuclear fission reactions are largely radioactive, and they generate a lot of thermal energy as they decay. It is decay heat that must be removed from a reactor that has just been shut down to keep it cool and prevent it from melting down. The control rods can do nothing to stop decay heat from the fission fragments, and cannot cool the core after shutdown. Only coolant and circulating pumps and heat exchangers can do this. But the tsunami knocked out power to the plant and damaged the emergency generators that provide the plant with back-up power. The cores overheated, went into meltdown, and the dominos continue to fall.
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Control rods should possess the following properties : 1. They should have adequate heat transfer properties. 2. They should be stable under heat and radiation. 3. They sh…ould be corrosion resistant. 4. They should be sufficient strong and should be able to shut down the reactor almost instantly under all conditions. 5. They should have sufficient cross-sectional area for the absorption
Boron rods are introduced into the reaction to slow it down when required.
Control the reaction rate by absorbing neutrons that are generated but not needed. They are typically made of cadmium or boron, elements that have very large neutron captu…re crosssections (a measurement of the statistical probability of a given nuclear interaction).
Sometimes screws are used, but hydraulics are also common (and that isn't a simple machine).