Steam-generating heavy water reactor

Steam-generating heavy water reactor (SGHWR) is a type of nuclear reactor that uses heavy water (deuterium oxide D2O) as its neutron moderator and coolant, but also generates steam for power production.

History

The SGHWR was developed in the United Kingdom during the 1960s and 1970s. The design was a direct descendant of the Magnox reactors, the first generation of British nuclear power plants. The first SGHWR was built at the Winfrith site in Dorset, England, and began operation in 1967.

Design and operation

The SGHWR design is unique among heavy water reactors in that it uses the heavy water not just as a moderator, but also as a coolant. This allows the reactor to operate at higher temperatures and pressures than other heavy water reactors, which in turn allows it to generate steam directly in the reactor core. This steam is then used to drive a turbine and generate electricity.

The fuel used in an SGHWR is typically uranium or plutonium, although other fissile materials can also be used. The fuel is contained in fuel rods, which are immersed in the heavy water moderator/coolant. The heavy water slows down the neutrons produced by the fission reactions, allowing them to cause more fissions and sustain the nuclear chain reaction.

Safety features

The SGHWR design includes several safety features. The heavy water moderator/coolant acts as a "heat sink", absorbing heat from the reactor core and preventing overheating. In addition, the reactor is designed to shut down automatically in the event of a loss of coolant accident (LOCA), a type of accident that could potentially lead to a nuclear meltdown.

Decommissioning

The Winfrith SGHWR was shut down in 1990 and is currently in the process of being decommissioned. The decommissioning process involves removing the fuel and other radioactive materials from the reactor, dismantling the reactor structure, and cleaning up the site.

See also

• Nuclear power in the United Kingdom
• List of nuclear reactors
• Nuclear decommissioning