Dounreay

Encyclopedia : D : DO : DOU : Dounreay

Dounreay (Ordnance Survey Grid reference ) is the name of a now ruinous castle on the north coast of Caithness, in the Highland area of Scotland. The castle, however, is within grounds used by the United Kingdom Atomic Energy Authority (Dounreay Nuclear Power Development Establishment) and the Ministry of Defence (HMS Vulcan). It is famous as the site of five nuclear reactors, three owned and operated by the UKAEA and two by the Ministry of Defence.

The nuclear power establishment was built on the site of a World War II airfield, called HMS Tern (II). The airfield was transferred to the Admiralty by RAF Coastal Command in 1944, as a satellite of HMS Tern at Twatt in the Orkney Isles. It never saw any action during the war and was placed into care and maintenance in 1949.

Dounreay is near the A836 road, about 9 miles (14 km) west of the town of Thurso, which grew rapidly when the research establishment was developed during the mid 20th century. The establishment has remained a major element in the economy of Thurso and Caithness since that period.

Contents

1 Etymology
2 Dounreay Nuclear Power Development Establishment

2.1 Nuclear Decommissioning Authority ownership

3 HMS Vulcan
4 See also
5 External links

Etymology

According to one story the name Dounreay came about after a local with a strong accent tried to pronounce Down Reay to a map maker (Down Reay being down the road from the village of Reay, with the now defunct post office at the entrance to the reactor establishment having had the correct name, Down Reay, above its door).

Robert Gordon's map of Caithness, 1642, uses Dounrae as the name of the castle.

Watson's The Celtic Place-names of Scotland gives the origin as Dúnrath, and suggests that it may be a reference to a broch. This is the commonly accepted toponymy.

Dounreay Nuclear Power Development Establishment

Dounreay in 2006.

Dounreay Nuclear Power Development Establishment operated by the United Kingdom Atomic Energy Authority (UKAEA), was the site of the UKAEA fast breeder reactor (FBR) power station program. Three nuclear reactors were built there by the UKAEA, two of them FBRs plus a thermal research reactor used to test materials for the program, and also fabrication and reprocessing facilities for the materials test rigs and for fuel for the FBRs.

The first of the Dounreay reactors to achieve criticality was the Dounreay Materials Test Reactor (DMTR), in May 1958. 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 the DIDO class reactor, and then chemically stripped of this coating after irradiation. DMTR was closed in 1969, when materials testing work was consolidated at Harwell Laboratory.

Schematic diagram showing the operation of the DFR, a NaK cooled FBR.

The second reactor to achieve criticality (although the first to commence construction) was the Dounreay Fast Reactor (DFR), which came on-line in November 1959, producing an electrical output of 14 MWe. This power was exported to the National Grid from 14 October 1962 until the reactor was taken offline for decommissioning in 1977. During its operational lifespan, DFR produced over 600 million units of electricity.

DFR was a loop-type FBR cooled by primary and secondary NaK circuits, with 24 coolant loops, and fueled with uranium oxide.

The third and final UKAEA-operated reactor to be built on the Dounreay site was the Prototype Fast Reactor (PFR), which achieved criticality in 1974 and began supplying National Grid power in January 1975. The output of PFR was 250 MWe. The reactor was taken offline in 1994, marking the end of nuclear power generation at the site. PFR was a pool-type FBR, cooled by liquid sodium and fueled with MOX.

Since the reactors have all been shut down and the decommissioning programmes have started, Dounreay has still retained much of its work-force by taking in and reprocessing shipments of spent nuclear fuel and waste.

Nuclear Decommissioning Authority ownership

On 1 April 2005 the Nuclear Decommissioning Authority (NDA) became the owner of the site, with the UKAEA remaining as operator. Decommissioning of Dounreay is planned to bring the site to an interim care and surveillance state by 2036, and as a brownfield site by 2336, at a total cost of £2.9 billion.

Apart from decomissioning the reactors, reprocessing plant, and associated facilities, there are five main environmental issues to be dealt with:

A 65-metre deep shaft used for intermediate level nuclear waste disposal is contaminating some groundwater, and is threatened by coastal erosion in about 300 years time. The shaft was never designed as a waste depository, but was used as such on a very ad-hoc and poorly monitored basis, without reliable waste disposal records being kept. In origin it is a relic of a process by which a waste-discharge pipe was constructed. The pipe was designed to discharge waste into the sea. Historic use of the shaft as a waste depository has resulted in one hydrogen gas explosion [link], and fears that accumulated material might represent a potential critical mass.
Irradiated nuclear fuel particles on the seabed near the plant, with some being washed ashore, including a small number on the public Sandside Bay beach. The way these particles escaped the site has not been determined, there are several plausible possibilities.
18,000 cubic metres of radiologically contaminated land, and 28,000 cubic metres of chemically contaminated land.
1,350 cubic metres of high and medium active liquors and 2,550 cubic metres of unconditioned intermediate level nuclear waste in store.
1,500 tonnes of sodium, 900 tonnes of this radioactively contaminated from the Prototype Fast Reactor.

Historically much of Dounreay's nuclear waste management was poor. Until 1990 Dounreay had Crown property status, which effectively meant site operators could not be prosecuted.

HMS Vulcan

Two other reactors on the Dounreay site are Ministry of Defence projects - Rolls-Royce pressurised water reactors (PWRs) used to test the design of reactors for use in the Royal Navy's nuclear-powered submarine fleet.

External links

[UKAEA Dounreay]
[Vulcan takes on additional role]
[Dounreay] - Scottish Parliament research note, 9 January 2001
[Dounreay - Fast Breeder]
[Dounreay - Overview of NDA's Draft Strategy]
[Dounreay Decommissioning Tasks]
[Dounreay shaft "dry cleaning"]
[The threats at Dounreay]

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