Inside the reactor vessel, the fuel rods are immersed in water which acts as both a coolant and moderator. The moderator helps slow down the neutrons produced by fission to sustain the chain reaction. Control rods can then be inserted into the reactor core to reduce the reaction rate or withdrawn to increase it.
In which way we can control nuclear chain reaction?
To maintain a sustained controlled nuclear reaction, for every 2 or 3 neutrons released, only one must be allowed to strike another uranium nucleus. If this ratio is less than one then the reaction will die out; if it is greater than one it will grow uncontrolled (an atomic explosion).
How do you stop a chain reaction?
The only way to control or stop a nuclear chain reaction is to stop the neutrons from splitting more atoms. Control rods made of a neutron-absorbing element such as boron reduce the number of free neutrons and take them out of the reaction.
What controls the chain reaction in a nuclear reactor quizlet?
By control rods and the moderator. They absorb neutrons allowing the reactor to produce energy at a steady rate. In a controlled chain reaction, on average only one neutron from each fission will strike another nucleus and cause further stimulated fission to occur.
How do you control the rate of a nuclear reaction in a reactor?
Answers. In a fission reactor, control rods absorb neutrons to control the rate of a reaction. Lowering the rods into the reactor decreases the rate of fission and removing them increases the rate.
What do control rods do in a nuclear reactor?
A rod, plate, or tube containing a material such as hafnium, boron, etc., used to control the power of a nuclear reactor. By absorbing neutrons, a control rod prevents the neutrons from causing further fissions.
Why is the chain reaction controlled in a nuclear reactor?
In a nuclear power station nuclear fuel undergoes a controlled chain reaction in the reactor to produce heat – nuclear to heat energy. The chain reaction is controlled by Boron control rods. … When the Boron absorbs the neutrons then the chain reaction will slow down due to lack of neutrons producing reactions.
What is controlled and uncontrolled chain reaction?
Controlled vs Uncontrolled Chain Reaction
A controlled chain reaction is a chain of nuclear reactions that take place subsequently under controlled conditions. An uncontrolled chain reaction is a chain of nuclear reactions that take place subsequently, but not under controlled conditions.
What triggers a nuclear chain reaction?
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.
Can we stop nuclear reaction?
To shut down a nuclear reactor, you need to stop the chain reaction. … However, once the chain reaction stops, ordinary nuclear reactions take over and will continue to generate heat albeit at a lower rate.
What is the purpose of the control rods in a nuclear reactor quizlet?
Control rods are used in nuclear reactors to control the fission rate of uranium and plutonium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.
How is a fission chain reaction controlled in a nuclear power plant?
The moderator helps slow down the neutrons produced by fission to sustain the chain reaction. Control rods can then be inserted into the reactor core to reduce the reaction rate or withdrawn to increase it. The heat created by fission turns the water into steam, which spins a turbine to produce carbon-free electricity.
What is the purpose of the chain reaction in a nuclear power plant quizlet?
A chain reaction results that releases energy and produces more neutrons. Energy released from the fission reaction heats a closed loop of water.
How are control rods move in a nuclear reactor?
Control rods are partially removed from the core to allow the nuclear chain reaction to start up and increase to the desired power level. … Control rods often stand vertically within the core. In PWRs they are inserted from above, with the control rod drive mechanisms mounted on the reactor pressure vessel head.
What do control rods and moderators do?
The moderator and control rods together control the rate of reaction in the core of the nuclear reactor. … The other neutrons that were released by the collision would cause a nuclear explosion if moveable control rods did not absorb them.
What are moderators and control rods in a nuclear reactor?
A moderator is a material used in a nuclear reactor to slow down the neutrons produced from fission. … Control rods are made from material with the ability to absorb neutrons; Cadmium and Boron are examples of suitable materials.