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For other uses, see Winfrith Newburgh and Winfrith (bishop).
Winfrith nuclear power station
Winfrith - - 294818.jpg
UKAEA sign
Winfrith is located in Dorset
Location of Winfrith nuclear power station in Dorset
Country England
Location Winfrith Newburgh, Dorset
Coordinates 50°40′55″N 2°15′40″W / 50.682°N 2.261°W / 50.682; -2.261Coordinates: 50°40′55″N 2°15′40″W / 50.682°N 2.261°W / 50.682; -2.261
Status Decommissioned
Construction began 1957
Commission date 1959
Decommission date 2021
Operator(s) UKAEA
Nuclear power station
Reactor type SGHWR
Thermal power station
Primary fuel Nuclear
Power generation
Nameplate capacity 100MW
grid reference SY815870

Winfrith Atomic Energy Establishment (or AEE Winfrith) was a United Kingdom Atomic Energy Authority site near Winfrith Newburgh in Dorset. It covered an area on Winfrith Heath to the west of the village of Wool between the A352 road and the London Waterloo to Weymouth railway line. It was home to a demonstration steam-generating heavy water reactor (SGHWR) providing power to the National Grid, as well as to a nuclear research facility.

Nuclear research[edit]

Winfrith Atomic Energy Establishment was built for the construction and operation of experimental and research reactors.[1] Construction began in 1957, and the first low-energy reactor (ZENITH) was completed and in operation by the end of 1959.[1] This was quickly followed by two others (NESTOR) in 1961 and (DIMPLE) in 1962.[1] The last reactor was shut down in 1995, although decommissioning of the site will not finish till 2021.[2] Winfrith housed several experimental reactors during its lifetime. There were also impact test facilities, and a used nuclear fuel examination facility with the associated hot cells.

Experimental reactors included:

  • ZENITH (Zero Energy High Temperature Reactor) built in 1959. It was a zero-energy reactor which was used to study the physics of high temperature reactors.[3]
  • NESTOR (Neutron Source Thermal Reactor) built in 1961. Based on the JASON reactor operated by the Hawker Siddeley Nuclear Power Corporation at Langley, Berkshire.[4] NESTOR was a small research reactor which produced a large amount of neutrons making it a useful tool for investigating the design of power-producing reactors and carrying out sub-critical experiments on core assemblies.[4]
  • DIMPLE (Deuterium Moderated Pile of Low Energy) built in 1962. Originally built at Harwell in 1954, Dimple was Britain's first heavy water reactor.[5] It was moved to Winfrith in 1962 and extensively modified and rebuilt for studies of the physics of reactor systems moderated by light or heavy water and by an organic moderator.[6]
  • ZEBRA (Zero Energy Breeder Reactor Assembly) built in 1962. Designed for studying the neutron physics of a wide variety of fuel assemblies containing uranium and plutonium.[7]
  • HECTOR (Hot Enriched Carbon-moderated Thermal Oscillator Reactor) built in 1963. Designed to examine the suitability of various materials for use in power reactors.[8]
  • JUNO, built in 1964. Built from the components of a zero-energy graphite moderated reactor called NERO, and from a sub-critical assembly used for steam generating heavy water reactor investigations, it was used to provide the information needed for the design of small power reactor cores.[9]
  • Dragon. The Dragon reactor was built in 1964.[1] It was the first power reactor built at Winfrith.[1] It was an experimental reactor built as a European inter-governmental research and development project.[1] It was the first demonstration high-temperature gas-cooled reactor (HTGR) and had a thermal output of 20 MW. It operated until 1976.

Winfrith Steam Generating Heavy Water Reactor[edit]


The largest reactor at Winfrith was a steam-generating heavy water reactor (SGHWR) commonly known as the Winfrith Reactor.[1] It was designed by the UKAEA, and was intended to combine the features of the CANDU reactor and PWR.[10] The core consisted of a bank of metal pressure tubes (zirconium alloy) which passed through vertical tubes in a tank of heavy water moderator – allowing the designers to do without the pressure vessel that normally contained the reactor's core.[11] The pressure tubes contained the fuel which was cooled by a flow of light water up the tubes, generating steam.[11] The fuel was slightly enriched uranium.[11] The power level was varied by the level of the moderator.[12] The reactor exported up to 100 MW of electric power to the National Grid.[11] For many years it was the largest water cooled reactor in the United Kingdom.[1]


Construction of the reactor began in 1963.[1] It began operating in 1967,[12] and was notable for being built within the allotted timescale (four years), and for being under-budget.[13] It was built as a demonstration reactor,[12] with the intention of building a series of commercial reactors based on the design.[10] However, the SGHWR design was never advanced beyond the prototype at Winfrith,[12] and the design was sidelined in favour of AGR reactors.[10] The Winfrith reactor was shut down in 1990.[12]

The site today[edit]

The site is now split between the nuclear licensed site, the extensive Dorset Green Technology Park (formerly Winfrith Technology Centre) and the headquarters of the Dorset Police, whose police helicopter is based there.

Ownership of the Winfrith Nuclear site has now passed to the Nuclear Decommissioning Authority (NDA). The site is managed by Research Sites Restoration Limited (RSRL)[2] who are contracted to deliver the site decommissioning programme. RSRL is a subsidiary of Cavendish Nuclear Limited, part of Babcock International Group.


  1. ^ a b c d e f g h i M S Barents (2000). "Decommissioning the Winfrith technology centre - Environmental Restoration with a Purpose". WM'00 Conference, February 27 - March 2, 2000, Tucson, AZ. 
  2. ^ a b Research Sites Restoration Limited website
  3. ^ "Southern Graduates visit Winfrith". The Chartered Mechanical Engineer (Mechanical Engineering Publications Limited) 7–8: 462. 1960. 
  4. ^ a b "The Rise of the Argonauts". New Scientist 6 (159): 1109. 3 December 1959. 
  5. ^ "Atomic energy abroad". Bulletin of the Atomic Scientists. 10-11: 333. 1954. 
  6. ^ "Steam Generating Heavy Water Reactor". The Indian & Eastern Engineer 117: 111. 1975. 
  7. ^ "Zebra at Winfrith". Electronics and Power (Institution of Electrical Engineers) 6: 480. 1960. 
  8. ^ "Atomic Reactor Research". Mechanical Engineering: The Journal of the American Society of Mechanical Engineers (American Society of Mechanical Engineers) 85: 70. 1963. 
  9. ^ "New AEA Reactor". The Electrical Review (Electrical Review, Limited) 174: 68. 1964. 
  10. ^ a b c Burton, Bob (1990). Nuclear Power, Pollution and Politics. Routledge. pp. 38–9. ISBN 041503065X. 
  11. ^ a b c d Kenward, Michael (17 August 1972). "Britain's nuclear options". New Scientist: 334. 
  12. ^ a b c d e Wood, Janet (2006). Nuclear Power. Institution of Engineering and Technology. pp. 38–9. ISBN 0863416683. 
  13. ^ Burton, Bob (1990). Nuclear Power, Pollution and Politics. Routledge. p. 123. ISBN 041503065X. 

External links[edit]