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All reactors require some form of controllable neutron absorber to accommodate power changes, which cause changes in the concentration of fission product neutron poisons such as Xenon, and to accommodate fuel burn up caused reactivity changes. The reactor must be held at criticality during steady operation and very near it during slow power changes, and moveable control rods are provided for this, usually containing boron which absorbs neutrons strongly. When the reactor is tripped or scrammed the rods drop fully in, and start up requires a slow careful approach to criticality.
The following applies to PWR's and is taken from Wikipedia
Generally, reactor power can be viewed as following steam (turbine) demand due to the reactivity feedback of the temperature change caused by increased or decreased steam flow. Boron and control rods are used to maintain primary system temperature at the desired point. In order to decrease power, the operator throttles shut turbine inlet valves. This would result in less steam being drawn from the steam generators. This results in the primary loop increasing in temperature. The higher temperature causes the reactor to fission less and decrease in power. The operator could then add boric acid and/or insert control rods to decrease temperature to the desired point. Reactivity adjustment to maintain 100% power as the fuel is burned up in most commercial PWRs is normally achieved by varying the concentration of boric acid dissolved in the primary reactor coolant. Boron readily absorbs neutrons and increasing or decreasing its concentration in the reactor coolant will therefore affect the neutron activity correspondingly. An entire control system involving high pressure pumps (usually called the charging and letdown system) is required to remove water from the high pressure primary loop and re-inject the water back in with differing concentrations of boric acid. The reactor control rods, inserted through the reactor vessel head directly into the fuel bundles, are moved for the following reasons: * To start up the reactor. * To shut down the reactor. * To accommodate short term transients such as changes to load on the turbine. The control rods can also be used: * To compensate for nuclear poison inventory. * To compensate for nuclear fuel depletion. but these effects are more usually accommodated by altering the primary coolant boric acid concentration.
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What is the place where controlled nuclear fission reactions take place?
The place where controlled nuclear fission reactions take place is called a nuclear reactor. In a nuclear reactor, uranium atoms are split in a controlled manner to produce heat energy, which is used to generate electricity.
Mechanism and container for controlled fission is called?
The mechanism for controlled fission is nuclear reactors, which utilize a controlled chain reaction to generate heat. The container used to house this process is typically a reactor core, which contains the fuel, control rods, and coolant necessary for maintaining the fission reaction at a steady rate.
How is a nuclear fission reaction controlled in nuclear reactor?
Reactions that involve nuclei, called nuclear reactions, result in a tremendous amount of energy. Two types are fission and fusion.
What does fission happen in?
Nuclear reactor
In a nuclear power plant fission reactions are controlled by inserting what?
In a fission reactor, control is implemented by inserting control rods into the reactor. These are made of a material that absorbs neutrons, and prevents a reaction from taking place.
A nuclear reactor uses the energy from a controlled?
nuclear fission
What is the place where controlled nuclear fission reactions take place?
The place where controlled nuclear fission reactions take place is called a nuclear reactor. In a nuclear reactor, uranium atoms are split in a controlled manner to produce heat energy, which is used to generate electricity.
What is the meaning of nuclear reactor?
It is a device where a controlled nuclear fission chain reaction occurs.
A nuclear reactor produces energy from uncontrolled fission?
False, the fission in nuclear reactors is controlled with the movable control rods.
Mechanism and container for controlled fission is called?
The mechanism for controlled fission is nuclear reactors, which utilize a controlled chain reaction to generate heat. The container used to house this process is typically a reactor core, which contains the fuel, control rods, and coolant necessary for maintaining the fission reaction at a steady rate.
How is a nuclear fission reaction controlled in nuclear reactor?
Reactions that involve nuclei, called nuclear reactions, result in a tremendous amount of energy. Two types are fission and fusion.
How is the rate of the fission in a nuclear reactor controlled?
The rate of fission in a nuclear reactor is controlled through the use of control rods made of materials like boron or cadmium. These control rods absorb neutrons, reducing the number available to cause fission reactions, thus regulating the rate of fission. By inserting or withdrawing these control rods into the reactor core, operators can adjust the level of fission and control the reactor's power output.
Is power reactor a thermal reactor?
Yes, a power reactor is a type of thermal reactor. Power reactors use nuclear fission to produce heat, which is then used to generate electricity. The heat generated in the reactor comes from the controlled chain reaction of nuclear fission, making it a thermal reactor.
What happens in a nuclear reactor to create electricity?
In a nuclear reactor, the controlled splitting of atoms (nuclear fission) generates heat, which is used to produce steam from water. The steam then drives turbines that are connected to generators, producing electricity. The process essentially harnesses the heat energy released during nuclear fission to produce electricity.
What does fission happen in?
Nuclear reactor
How is the controlled release of nuclear energy in a reactor is accomplished by?
Controlled release of nuclear energy in a reactor is achieved by controlling the rate of nuclear fission reactions through the use of control rods. These control rods absorb neutrons, limiting the number available to initiate fission reactions. By adjusting the position of the control rods, the reactor's power output can be regulated to maintain safe and efficient operation.
Where is the nuclear energy produced in a nuclear reactor?
Nuclear energy is produced in the core of a nuclear reactor, where controlled nuclear fission reactions occur. These reactions release heat energy, which is then used to generate electricity through steam turbines.
