Dounreay (United Kingdom)

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2 FBR Prototype reactors; 15 MW - started operation in 1962; 250 MW started operation 1975; Reprocessing plant for FBR fuel.

The Prototype Fast Reactor "Dounray" generated power for the UK grid from 1976 until 1994. It was built as the prototype for a new generation of UK advanced reactors but did not perform to expectations. It is also proving difficult to decommission due to the activation of its liquid sodium coolant.
(source: world nuclear news)

Facilities in Dounreay

plantreactor typconstruction startoperation startshut down
Dounreay complexFBR
Dounreay FR 1FBR195519621977

"On 12 November 2002, two contractors leaving the D2001 Intermediate Level Waste Processing facility were found to have contaminated shoes and one had contamination on his hands. All personnel in the building were withdrawn and monitored, and as a result contamination was revealed on the shoes of a further fifteen individuals. Of these, one other person had contamination on his hands and face. The two individuals with personal contamination were sent to the Occupational Health Department where decontamination was successfully carried out the following day.

In parallel with UKAEA's investigation, an investigation into the incident was carried out by NII commencing at site on 13 November 2002. The investigation concluded that the source of the contamination was the leakage of a small quantity of contaminated Zinc Bromide liquid from a flask. This had been swabbed up from the inside of a shielded waste cell and placed in a waste container which was then posted out of the cell into the flask for processing and consignment for storage. The flask, waste container and the associated bagging system is not designed to provide containment of free liquids and the Zinc Bromide leaked to the outside of the flask and was spread around the working area on the shoes of the workers.

The actual doses received by the individuals affected by the incident were confirmed to be very low. In addition, checks of the discharge stack monitors concluded that there was no evidence of a release to the environment.

NII's investigation report revealed a number of shortcomings which are being addressed by UKAEA. An Improvement Notice was served under the Ionising Radiation Regulations 1999 (IRRs) requiring improvements to be made to the flasking system design and operations.

The incident has been classified as Level 0 on the International Nuclear Event Scale."


Dounreay presently has an inventory of 109 tonnes of irradiated and unirradiated fuel. The UK Atomic Energy Authority (UKAEA) originally planned to reprocess the PFR fuel at a dedicated plant, named D 1206, where 30 tonnes of irradiated fuel was reprocessed between 1980 and 1996. Last September that plant was shut down after a leak was discovered in a dissolver. The cost of replacing the equipment and re-opening the plant was estimated at more than UK 130 million pounds. In June 1998 the government announced that commercial reprocessing would stop at Dounreay following the completion of existing contracts.

The stockpile of fuel remaining at the Caithness plant, which is being decommissioned at a cost of UK 4 billion pounds will not be reprocessed at Dounreay. Dounreay's operators, UKAEA will have to offer further examine options, including storing on site or sending it elsewhere to be reprocessed.


The Prototype Fast Reactor is the subject of a 17-million-pound contract, covering disposal of its liquid metal coolant, awarded to NNC Ltd. in October 1995. The government's 500-million-pound "core program" of work at Dounreay until 2005 centers on decommissioning the two fast reactors and reprocessing PFR fuel.
DFR, a fast reactor cooled by a liquid sodium-potassium alloy (NaK), was constructed in the mid-1950s. Since its closure in 1977, its core fuel, except for one element, has been unloaded and reprocessed and the secondary circuit NaK coolant removed. Most of the metallic uranium breeder fuel remains, some of it stuck in place, immersed in some 57 metric tons of primary circuit NaK which has to be kept heated to maintain it in a liquid state.
The five-year contract Rolls Royce signed May 8 is concentrated on NaK removal and treatment together with maintenance of several shut-down plants within the Dounreay Fuel Cycle area. The engineers' most complicated task is expected to be removal of NaK that has pooled in DFR by-pass vessels.
The advantage for Rolls Royce undertaking this work is the PDS team's plant knowledge. Government-driven UKAEA sees bringing in private-sector expertise such as that from Rolls Royce as a chance to capitalize on new techniques and efficiencies. Rolls Royce will undoubtedly use the expertise of PDS in other areas.
The NaK removal and treatment is only one discrete package, he said, and more projects are expected to be up for tender shortly. One in which the Rolls Royce/PDS group could have an edge is DFR's water-filled storage pond which will be coming up for decommissioning soon, because PDS did in fact operate that pond when it was a working facility.


A planning committee in Scotland has given the green-light to a plan for the construction of a new treatment plant for low-level liquid effluent at the UKAEA´s Dounreay site.
The now above-ground facility will completely replace existing installations which include underground storage. The construction project is scheduled for completion in 1998. A Dounreay spokesman said the new treatment plant would be a further help in widening the gap between Dounreay´s actual discharges and the levels set by the regulators.


Shutdown of a reprocessing plant after detection of contaminated waste water discharged to sea. The waste water was from reprocessing of unirradiated fuel from Dounreay's FBR prototype: The water was contaminated with alpha emitters; The discharge was 7 GBq, while the annual limit is 750 Gbq.


Major scan of the site to detect any remaining radioactive particles that could be buried in the soil, after the discovery of 20 hot spots in June in July. 67 patches of lesser contamination have also been detected.. More than 100 radioactive metallic particles have been found on Dounreays foreshore (= area between high and low- water lines) since 1979. Hot particles were found as UKEA excavated on-site roadside areas to install cables. tests showed ll hot particles to be fragments of Material Test Reactor fuel consosting of uranium & aluminium irradiated in the mid. 1960s. The radiological component si dominated by Cs-137.
Another report assumes the source of hot particles was an hydrogen explosion in 1977, which blew off the concrete roof slab of a shaft and expelled an unquantified amount of debris .
Activities of the hot particles are in the range of 10E6 to 10E8 Bq. Doses from swallowing such particles would givve an equivalent bone marrow dose of tens of mSv & could cause a significant increase in the leukemia risk..
The report explains that the metallic particle are most unlikely the cause of the observed increase of childhood leukemia risk in the <Dounreay area because of the very low probability of encountering such particles: "..only one had ever been found on a publöic beach" & "the Dounreay shore area, although not closed to the public until recently, has always been difficult to access.


Plutonium dust blew out from a glove box: seven employees were working in the area, One was contaminated by dust. The leak was caused by a blocked filter and most of the dust exited the building via stack ( discharge was 2% of annual limit).
Details published in August: 2 of the 7 workers received significant doses (approx. half of annual limit); Pu released off-site through the stack amounted to 1% of the annual limit.


Synchronization to the grid after a 19 month outage was aborted because of severe storms which ripped at the 100 mile -long cable connecting it to the grid -> reactor tripped.


Secondary cooling circuit sodium leak -> shutdown. Leak was running along the edge of 1 of 2 repairs made to the reheater vessel in 1987. Inspection revealed further defects. Current vessel leakage is different from the problem the unit had in the 1980s, when the tube bundles inside the superheater and reheater vessels were leaking. All 6 superheater and rehaeter bundles in the vessels of the 3 secondary circuits were replaced between 1984 and 1987, using an improved alloy at a cost of 28 million pounds (US$ 46 million). In 1987 also a leak was discovered in the vessel itself. US inspection uncovered some more defects at major welds, leading to repairs. The recent defects are connected with this repairs from 1987. The now required repairs cost about 1 million pounds (US$ 1.68 million )