UKAEA appeared at Wick sheriff court on 6 February to plead guilty to four charges under the Radioactive Substances Act 1960.
Between 1976 and 2006, 1,401 radioactive particles were recovered, most of which are the size of a grain of sand. The exposure risk is said to be small but the particles could prove fatal if ingested. Fishing is banned in a two-kilometre radius around the site’s effluent outfall.
Dounreay ceased operation in 1994. A damning report by the Nuclear Installations Inspectorate in 1998 revealed a poor management history by UKAEA and lax regulation by former environmental watchdog HM Industrial Pollution Inspectorate (ENDS Reports 281, pp 18-22 and 283, p 9 ).
The Dounreay Particles Advisory Group was set up in 2000 as an independent panel to advise the Scottish Environment Protection Agency on the particles. A report by the group in March 2003 prompted SEPA to investigate the site’s discharges, which eventually led to a prosecution.
Another recent report by the group confirmed that working practices since the late 1950s had caused particles to be released.
SEPA’s investigation found that the radioactive particles in the site’s effluent came from three different fuel-handling processes.
The main source was the material test reactor pond, where an underwater milling machine removed the metal casings of spent nuclear fuel rods.
The process released metal particles into the water. Between 1963 and 1984 it was common practice to discharge the water to sea via the outfall. Holding tanks were not effective in removing the particles and, certainly in the early days of the site’s operation, any sediment was washed into the drains. It was therefore not surprising that SEPA found evidence of particles remaining in wastewater monitoring tanks between the pond and the outfall.
SEPA uncovered similar failings at another fuel pond serving the reprocessing plant and in the fuel dissolving and washing process for the site’s fast reactor.
UKAEA was charged with failing to take all reasonable practical means to prevent the release of radioactive particles, contrary to section 13(1)(c) of the 1960 Act and was fined £60,000.
The authority was also charged on three counts of disposing of radioactive waste without an authorisation, contrary to sections 6(1) and 13(1)(a) of the 1960 Act.
The first led to a £40,000 fine after records showed contaminated material was deposited at a landfill site intended for only inert waste between 1963 and 1975.
SEPA became aware of the issue in 1998 and was concerned the sea was eroding the site. The landfill contained 45,000 cubic metres of material and the authority removed 7,000m3 from the area most at risk from erosion. Tests revealed 43m3 of this was low-level radioactive waste.
UKAEA was fined £20,000 after it found radioactive particles in surface water drains under the material test reactor building in 1999. The source was found to be a misconnected fuel flask washing process which had been discharging from 1964-67.
The final charge, which led to another £20,000 fine, related to an incident in 1964 when UKAEA was transferring water through a temporary pipeline to top up a fuel-handling pond. The pipeline was ruptured when a vehicle ran over it, allowing contaminated water to escape from the pond. The fire brigade washed the water into surface drains.
In a statement, UKAEA safety director John Crofts said: "The court today has passed judgment on the standards and practices of waste management more than a quarter of a century ago. We accept that mistakes were made and regret those mistakes. We, too, share the view that this is an unacceptable legacy of the Dounreay experiment."