Tag: nuclear reactor

Questions Related to nuclear reactor

A nuclear reactor must consist of which of the following parts?
I. Electric generator
II. Fissionable fuel elements
III. Moderator

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. I only

  2. III only

  3. I and II only

  4. II and III only

  5. I, II and III

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Correct Option: D
Explanation:

A nuclear reactor must consist:
 II. Fissionable fuel elements such as U-235 and Pu-239.
III. Moderator (heavy water) which slows down the speed of neutrons.

Boron rods, in a nuclear reactor, are used as.

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. moderator

  2. Protective shield

  3. Coolants

  4. Control rods

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Correct Option: A
Explanation:

Control rods are used in nuclear reactors to control the fission rate of uranium and plutonium. It is achieved by removing the excess neutrons from the reactor core. The only way to remove the excess neutrons through some elements which posses strong neutron absorption capacity. One such element is boron. By regulating the movement or insertion of boron rods into the reactor core while fission process is in progress, the excess neutrons produced during the chain reaction are absorbed by boron which rods regulate the availability of neutron. 


Best neutron moderator is.

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. Beryllium oxide

  2. Pure water

  3. Graphite

  4. Heavy water

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Correct Option: B
Explanation:

Pure water 

Neutron moderator is a medium that reduces the speed of fast neutrons.  Commonly used moderator is regular (light)  water(around 75% of the worlds reactors) 

A disadvantage of nuclear power is - 

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. it produces carbon dioxide which is responsible for global warming

  2. it produces toxic waste

  3. it affects the ozone layer

  4. it requires large amounts of fuel to produce a small amount of energy

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Correct Option: B
Explanation:

Nuclear fuels are non-renewable sources of energy and large amount of radioactive materials, which are toxic in nature, are released in the environment which are extremely hazardous to the health of living being for thousands of years.

Cadmium rods are used as moderators in a nuclear reactor.

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. True

  2. False

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Correct Option: B
Explanation:

Commonly used moderators include regular(light) water (roughly 75% of the world's reactors), solid graphite (20% of reactors) and heavy water (5% of reactors). Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility.

Best moderator for neutron is

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. berillium oxide

  2. pure water

  3. heavy water

  4. graphite

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Correct Option: C
Explanation:
Heavy water is best moderator
Moderator-This is a material which slows down the medium speed of neutrons produced by fission

In a nuclear power plant, uranium atoms

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. combine and give off heat energy

  2. split and give off heat energy

  3. burn and give off heat energy

  4. split and give off electrons

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Correct Option: B
Explanation:

A nuclear reactor produces and controls the release of energy from splitting the atoms of Uranium. Nuclear plants do not burn anything to create steam. Instead they split uranium atoms in a process of fission

Boron rods are used in nuclear reactor as

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. moderator

  2. control rods

  3. coolant

  4. protective shield

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Correct Option: B
Explanation:
Control rods are used in nuclear reactors to control the fission rate of uranium an plutonium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning
The wide absorption spectrum of boron makes it suitable as neutron shield

High energy neutrons are used in a nuclear reactor to initiate the fission reaction.

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. True

  2. False

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Correct Option: B
Explanation:

Slow moving/low energy neutrons are used to initiate the fission reaction

Which of the following controls the chain reaction in a nuclear reactor?

chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

  1. Molecules of high energy

  2. Ions

  3. Active hydrogen

  4. Moderator

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Correct Option: D
Explanation:

Moderator is used in nuclear reaction as  it can slow down the fast nuclear chain reaction by slowing down the neutron from fission to thermal energies.