Dragon Project
Joint project

View of Dragon Reactor. Photo: AEA Technology.

In 1959, twelve OECD countries began the Dragon Reactor Experiment (DRE) to build a reactor at Winfrith in Dorset, United Kingdom. The Dragon was the first experimental high temperature gas-cooled reactor (HTGR) built in the 1960s. Dragon used helium gas coolant and graphite as the neutron moderator. Fuel was formed into tiny spherical pellets and then coated with ceramics. These were then mixed with the graphite and pressed together to form blocks of various shapes and sizes. Dragon was operated by the United Kingdom Atomic Energy Authority. 

The reactor, which operated successfully between 1966 and 1975, had a thermal output of 20 MW and achieved a gas outlet temperature of 750°C. The high temperature reactor concept, if it justified its expectations, was seen as having its place as an advanced thermal reactor between the current thermal reactor types such as the pressurised water reactor (PWR), the boiling water reactor (BWR), the advanced gas-cooled reactor (AGR) and the sodium-cooled fast breeder reactor. It was expected that the high temperature reactor (HTR) would offer better thermal efficiency, better uranium utilisation, either with low enriched uranium fuel or with high enriched uranium thorium fuel, better inherent safety and lower unit power costs. All these potential advantages were demonstrated to be achievable, in principle during the project. This view is still shared today. In fact, a very high temperature reactors is one of the concepts retained for Generation IV and several countries are considering HTR technology as one of the promising concepts to be utilised for Small  Modular Reactors (SMR). Projects on constructing and operation of modular pebble-bed reactors (PBR) are also under way.

Project documentation and data can be accessed through request to the NEA data bank at IRPhE-DRAGON-DPR, OECD High Temperature Reactor Dragon Project, Primary DocumentsAn index of the titles of the reports in the data bank package is available here. Index DRAGON.


Altogether, 12 nations participated in Dragon, either individually or collectively through Euratom and the European Communities: Austria, Belgium, Denmark, France, Germany, Italy, Luxembourg, Netherlands, Norway, Switzerland, Sweden, United Kingdom

Funding came from government sources and was channelled to the Project through the Signatories to the Dragon Agreements. The Signatories, seven in all, included governments as such, atomic energy commissions and Euratom.

Project period



£47 335 000