How Nuclear Reactors Work
When an atom undergoes fission it splits into smaller atoms, other particles and releases
energy. Read about the physics of fission
. It turns out that it is
possible to harness the energy of this process on a large enough scale for it to be a
viable way of producing energy. Read about how power plants work
The fundamental point about nuclear energy is that the energy content of 1 gram of Uranium is equivalent to approximately 3 tonnes of coal. This means that we
need to consume about 3 million times less
material with Nuclear Power compared to using Coal or
any other Fossil Fuel. This substantially reduces the volumes of fuel and waste of nuclear power compared to Fossil Fuels.
The Different Types of Nuclear Reactors
There are are a number of different types of Nuclear Reactors currently in operation throughout the world. Some of the most common types are described here.
Pressurized Water Reactors
Pressurized Water Reactors (PWR's) are by far the most common type of Nuclear Reactor deployed to date. Ordinary water is used as both neutron moderators and coolant. In a PWR the water used as moderator and primary coolant is separate to the water used to generate steam and to drive a turbine. In order to efficiently convert the heat produced by the Nuclear Reaction into electricity, the water that moderates the neutron and cools the fuel elements is contained at pressures 150 times greater than atmospheric pressure. You can find out more details of PWR reactors at the following link.
Pressurized Water Reactors.
Boiling Water Reactors
In a Boiling Water Reactor (BWR), ordinary light water is used as both a moderator and coolant, like the PWR. However unlike the PWR, in a Boiling Water Reactor there is no separate secondary steam cycle. The water from the reactor is converted into steam and used to directly drive the generator turbine. These are the second most commonly used types of reactors. Find out more about Boiling Water Reactors at the following link.
Boiling Water Reactors.
High Temperature Gas Cooled Reactors.
High Temperature gas cooled reactors operate at significantly higher temperatures than PWRs and use a gas as the primary coolant. The nuclear reaction is mostly moderated by carbon. These reactors can achieve significantly higher efficiencies than PWRs but the power output per reactor is limited by the less efficient cooling power of the gas. You can find out more about these types of reactors at the following link.
High Temperature, Gas Cooled pebble reactors
Heavy Water Reactors
Heavy Water reactors are similar to PWRs but use water enriched with the deuterium isotope of Hydrogen as the moderator and coolant. This type of water is called "heavy water" and makes up about 0.022 parts per million of water found on Earth. The advantage of using Heavy water as the moderator is that natural, unenriched Uranium can be used to drive the nuclear reactor. You can find out more about these reactor types at the following link.
CANDU Heavy Water Reactors