This reactor is a PWR reactor - a pressurized water reactor. This is a specific type of Nuclear ReactorNuclear ReactorIn it's most simplest form, a nuclear reactor uses Uranium and other radioactive materials and the fission from uranium to create heat, and transfer that heat into steam to create power. Nuclear reactors are one of the biggest sources of energy, although not renewable, uranium has a very high energy density resulting in massive power transmissions. There are many different types of nuclear reactors, and this term serves as a broad hub/introduction for each type. After uranium is used in reacto--in that it is pressurized water. This is also the most common type of reactor used and produced.

The fuel rods are pressurized with helium, and the fission gas products result in more stability; as fuel "burns" in the reactor, the density increases resulting in small voids developing. Helium pressurization is necessary as these voids can cause potential rupture of fuel rods. Furthermore, the fuel rods are fitted with zirconium alloy claddingCladdingCladding is the thin walled metal tube that composes the outside of a fuel rod. It's purpose is to prevent corrosion of the fuel by the coolant & release of fission contents into the coolant. Although Zirconium alloy is common, aluminum and stainless steel is also used. Cladding Types Zirconium alloy has been used for so long due to it's properties being very good for nuclear reactors. * New research suggests that there is an alternative - SiGA cladding. This cladding is made from silicon car, necessary for maximum efficiency.

Since it uses Light WaterLight WaterLight water, although appearing to have a fancy name, is literally just ordinary water....except it does contain a small amount of Heavy Water. The point of light water is that it can be used as a moderator --however it can only be used in certain situations, as it absorbs too many neutrons to be used with unenriched uranium (which is why light water is presumably used in Spent Fuel Pools) Light water is mainly used in BWR reactors & PWR reactors Uranium Enrichment is necessary for the usage of, it has protection from both a LOCA and loss of moderator turning into steam as the moderator is directly necessary to keep the chain reaction.

Why is it pressurized?

The water is pressured bc the boiling point of water increases with pressure. This means that at a high pressure, the water can be raised to a high temperature without turning into steam, making it a source of very high thermal efficiency. This pressure is maintained with a pressurizer inside of the vessel.

By keeping water in liquid form, control rods can be placed in the top, resulting in increased safety, as the electromagnetic system holding rods can immediately drop for increased safety - gravity with do the work. This photo shows the inverted U bundles inside of the steam generator in a PWR The hot water from reactor flows through a heat exchanger made of U pipes, heating up the secondary loop (steam generation) - this loop is at a lower pressure as so it can boil to steam. Large reactors can have up to 4 gens, which may even be larger then the reactor itself.

Pressurized Heavy Water Reactor

A pressurized heavy water reactor is same in principle to a PWR, except that it contains Heavy WaterHeavy WaterHeavy Water is literally Deuterium oxide. It's molecular formula is that of regular Light Water--H2O, however it contains two atoms of deuterium and one atom of Hydrogen; resulting in 2D2O. It is about 10.6% denser than tap water and has a higher melting point, tasting slightly sweeter and can affect bioloigcal systems; large amounts are needed to poison humans, although it is toxic. It is produced using the Girdler sulfide process, and the usages of Heavy Water is mainly for nuclear science; as its cooland and neutron moderator. It primarily uses natural uraniumUraniumNatural Uranium VS \#stub, although it may also use uranium that is enriched to a low degree.

The primary benefit of heavy water is its low absorptions of neutrons results in better neutron economy, avoiding the need for enriched fuel. There are approximately 31 PHWRs currently in operation.

The advantages of heavy water as a moderator means that it can use uranium without enrichment. This is because the PHWR has its moderator at lower temperatures, meaning that thermal neutrons produced have lower energies, and therefore the neutron cross section for fission is higher as the temp decreases, making successful interactions more likely.

CANDU ReactorCANDU ReactorA CANDU reactor is a canadian PHWR design for the gneration of power. CANDU stands for CANada Deuterium Uranium; it uses Heavy Water containing deuterium oxide as its moderator and originally designed to use natural Uranium fuel.

CANDU reactors are part of the Pressurized Heavy Water Reactor family.