What are nuclear moderators made of?

Typically-used moderator materials include heavy water, light water, and graphite. The relative properties of these materials are compared below. The moderators vary in terms of their moderating abilities, as well as in their costs.

What is the most common material used as a moderator in a nuclear reactor?

In traditional nuclear reactors, the moderator is the same thing as the coolant: it’s water! When fast neutrons strike the hydrogen atoms in H2O, they slow down a lot (like a billiard ball striking another). There are other good moderators like graphite, beryllium, and more.

Which material can be used as a moderator?

Moderator and Coolant Other popular moderators are graphite, heavy water, sodium, and CO2. These materials should have low neutron absorption cross-section and can also act as coolant requiring high thermal conductivity and heat capacity to absorb the heat.

Why is water a better moderator than graphite?

Water and carbon (graphite) are commonly used moderators. Water is a good moderator, but the hydrogens in the water molecule have a fairly high cross section for neutron capture, removing neutrons from the fission process. Heavy water, used as moderator in Canadian reactors, avoids this loss.

Which country produces the largest share of electricity generated by nuclear power?

Nuclear reactors in France generated 382.4TWh of electricity in 2019. The country generates roughly 70% of its electricity from nuclear energy, the highest share of nuclear power in total power production.

Which type of reaction is used in nuclear reactors?

Nuclear reactors are the heart of a nuclear power plant. They contain and control nuclear chain reactions that produce heat through a physical process called fission. That heat is used to make steam that spins a turbine to create electricity.

Which is the most commonly used moderator?

Water (sometimes called “light water” in this context) is the most commonly used moderator (roughly 75% of the world’s reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives.

What is main function of moderator?

Moderators are the substance that slows down the neutrons in nuclear reactors. Moderators are made up of materials with light nuclei that do not absorb the neutrons but slow down the speed of neutrons by a series of successive collisions.

Which is a better moderator graphite or water?

Who is the best moderator?


  • Chuck Todd, Host of Meet the Press and MTP Daily & NBC News Political Director.
  • Scott Pelley, Award-Winning 60 Minutes Correspondent.
  • Dana Perino, Co-host of Fox’s America’s Newsroom and Former White House Press Secretary.
  • Norah O’Donnell, Co-host of CBS This Morning.

How is the moderator used in nuclear power?

The moderator is a material which slows down the speed of the neutrons . The moderator is usually made from water but some reactors use graphite. Neutrons released from the chain reaction must be moving at the right speed for other atoms of uranium to capture them. If the neutrons are moving too fast then they do not…

Can a water cooled water reactor use a moderator?

In the proposed water-cooled supercritical water reactor (SCWR), the proportion of fast fissions can exceed 50%, which technically is a fast neutron reactor. A fast reactor does not use any moderator, but is based on fission produced by fast, unmoderated neutrons to sustain the chain reaction.

What kind of materials are used for neutron moderators?

When this process is repeated the fissile events are doubled each time. There are several different types of moderating materials, and each have places where they are used more effectively. Typically-used moderator materials include heavy water, light water, and graphite. The relative properties of these materials are compared below.

How are neutrons used in a nuclear reactor?

The objective of the moderator is to reduce this speed and, in this way, obtain a better performance of the reactor. Neutrons, due to their speed, have a high kinetic energy. When encountering atoms of the moderator material, the neutrons collide with these atoms transmitting part of their kinetic energy to the nuclei of the moderator atoms.