page_title: Dounreay
section_title: Dounreay Materials Test Reactor
hierarchical_section_title: Dounreay / Dounreay Nuclear Power Development Establishment / Dounreay Materials Test Reactor
context_page_description: Dounreay is a scattered settlement with two large nuclear sites on the north coast of Caithness in the Highland area of Scotland. It is on the A836 road nine miles west of the town of Thurso. Dounreay was originally the site of Dounreay Castle and its name derives from the Gaelic for 'fort on a mound,' and consists of Upper Dounreay and Lower Dounreay.
  Lower Dounreay has been the site of two separate nuclear establishments since the 1950s; the Nuclear Power Development Establishment for the development of civil fast breeder reactors, and the Vulcan Naval Reactor Test Establishment, a submarine reactor testing facility. Most of these facilities are now being decommissioned. The establishments have been a major element in the economy of Thurso and Caithness, but this may decrease with the progress of decommissioning of the NPDE site. However an announcement in July 2020 that Nuclear Decommissioning Authority will be taking over direct management of that site from the site licence company Dounreay Site Restoration Limited in 2021, has alleviated fears of 560 job losses.
context_section_description: The first of the Dounreay reactors to achieve criticality was the Dounreay Materials Test Reactor (DMTR) in May 1958, which was a DIDO class research reactor, producing a high neutron flux. This reactor was used to test the performance of materials under intense neutron irradiation, particularly those intended for fuel cladding and other structural uses in a fast neutron reactor core. Test pieces were encased in uranium-bearing alloy to increase the already high neutron flux of this class of reactor, and then chemically stripped of this coating after irradiation. DMTR was closed in 1969 when materials testing work was consolidated at Harwell Laboratory.
caption: Schematic diagram showing the operation of the DFR, a NaK cooled FBR.                                   Key 1Fissile Pu-239 core 2Control rods 3U-238 Breeder blanket 4Primary NaK coolant loop 5Secondary NaK coolant loop 6Secondary NaK circulator 7Secondary heat exchanger 8Primary heat exchanger 9Primary NaK circulator 10Boronised graphite neutron shield 11Radiation shield