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control rods act like brakes to slow the neutron chain reaction rate in normal operation. the SCRAM system acts in emergencies to completely bring the neutron chain reaction to an instant stop. even with the reactor stopped, the cooling system must operate to prevent overheating from the radioactive decay of the built up fission products.
What else can I help you with?
How can nuclear fission be slowed?
Nuclear fission can be slowed by inserting control rods, such as boron or cadmium, into the reactor core. These control rods absorb neutrons, reducing the number available to initiate fission reactions and thus slowing down the rate of fission in the reactor.
What control the chain reaction in a nuclear reactor?
The chain reaction in a nuclear reactor is controlled by inserting control rods made of materials like boron or cadmium into the reactor core. These control rods absorb neutrons and help regulate the rate of the chain reaction by adjusting the number of neutrons available for fission. Moving the control rods in or out of the core allows operators to control the power level and ultimately, the reaction itself.
Limitation for Control rod in absorbing neutrons?
Control rods are designed usually to be effectively 'black' which means they absorb all incident slow neutrons, by having enough boron or other material in them to do this. The nuclear physics effect that this has on the reactor will then depend on the geometry of the arrangement, ie how many rods are provided in what sort of array and in how many places in the reactor compared with the array of fuel assemblies. This is decided by the nuclear design of the reactor, there are now adequate physics design programs to calculate what is required for a particular reactor. For safety the control rod capacity must be enough to always be able to shutdown the reactor and hold it down with an adequate margin, whatever the reactor state, which varies with refuelling and burnup when neutron absorbing fission products are taken into account. So it is quite a complicated calculation but one that can be done with certainty.
How do you make an atom into a different element?
This will happen naturally if the element is radioactive and can be done artificially by means of neutron bombardment in a nuclear reactor or in the heart of a star.
Can nuclear wastes cause explosions?
Nuclear waste can not case an explosion is it's spent form. Once a reactor is done with Uranium rods as fuel they are put into lead lined containers and transported to spent fuel storage. A nuclear reactor can explode from hydrogen build up in the containment vessel, this is due to the reaction going on in the steam generation process, this does not happen in nuclear waste storage facilities.
How is the rate of the fission reaction regulated in a nuclear reactor?
There are many ways this can be done: (increases/decreases the reaction rate)remove/insert control rods (most common method used)insert/remove fuel rodsmove fuel rods together/apartmove reflector toward/away the coreadd/withdraw moderator (this happens automatically in BWR as boiling creates voids in the water moderator, causing the reactor to regulate itself)etc.
What new thing going in the field of nuclear fusion reactor?
There is a new reactor in Europe, a joint EU project, that will be producing a net increase in power when opperational (which has not yet been done on any large scale). There are also plans for a reactor of a similar design that will commercialy produce electricity which will be fed onto the grid.
How did Enrico Fermi invent the nuclear reactor?
He was in charge of a team which first demonstrated that a nuclear chain reaction could be produced. This was in December 1942 and was done under the Manhattan Project during WW2, under very secret security at the time, in Chicago. The techniques were applied to the much larger reactors built at Hanford Wa which produced the required plutonium for weapons. None of these reactors produced electricity.
How are nuclear reactions controlled in power plants?
A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate. The heated water rises up and passes through another part of the reactor, the heat exchanger. The moderator/coolant water is radioactive, so it can not leave the inner reactor containment. Its heat must be transferred to non-radioactive water, which can then be sent out of the reactor shielding. This is done through the heat exchanger, which works by moving the radioactive water through a series of pipes that are wrapped around other pipes. The metallic pipes conduct the heat from the moderator to the normal water. Then, the normal water (now in steam form and intensely hot) moves to the turbine, where electricity is produced.
How do you calculate the yearly output of a nuclear reactor?
The electrical output of the plant is accurately and continuously measured by normal electrical equipment. To get the nuclear reactor thermal output, it is basically necessary to know the coolant flow rate and the temperature rise. In a BWR you would also need to know the steam content of the reactor outlet. These calculations would not be done frequently but would be done at intervals to check the plant efficiency. An approximate indication of reactor power can be obtained from neutron flux measurement directly, but this is used to help the operators rather than for an accurate power measurement, because there are variations in instrument sensitivity as well as in the flux distribution in the core.
What is the function of shielding in a nuclear reactor?
The first line of shielding is to limit the neutron bombardment of the pressure vessel, to give it a safe life of 40 or more years. Then you need to protect personnel who have to go into areas close to the reactor for maintenance, and also to limit the exposure of equipment which may need maintanance done during the life of the plant
What is done with the Pu 239 from a fast breeder reactor?
The idea is to use it for nuclear fuel in other reactors, this is why it is called a breeder process. Uranium-238 which is not fissile is converted to Pu-239 in the breeder reactor, but of course there is a chemical separation process to go through before the Pu is available.
