ABSTRACT

The United Kingdom Atomic Energy Authority IS responsible for several major nuclear establishments including the one located at Dounreay on the north coast of Scotland In recent years, radioactive particles, similar in size to sand grams, have been found on the seabed in the adjacent waters UKAEA is addressing this problem and is determined to identify their source, their spatial distribution in the offshore sediments and their net long term movement

INTRODUCTION

Routine environmental monitoring over the past 17 years of the Dounreay foreshore, which is closed to the public, has been finding radioactive metallic particles at an average of 12 per year A small number of particles (eight in total up until February 2000), all of low activity, have also been found on the nearby public beach at Sandside, which lies approximately 2 km to the west of the Dounreay site Although these particles have been assessed independently as presenting a negligible risk to the public, substantial effort has been put In to finding their source Several transport routes were mooted from wind borne to seabirds, but the most probable was likely to be from offshore sediment transport mechanisms

HISTORY

Work began on the Dounreay site In 1955 Until 1994, Dounreay's central task was the development of the fast reactor which allows very efficient use of uranium fuel in nuclear electricity generation, but the site was also used for manufacturing and reprocessing research and prototype reactor fuels The fast reactor programme was ended in 1994 All three reactors at Dounreay, MTR, DFR and PFR are now shut down and the major activity on the site IS decommissioning and waste management Currently Dounreay directly supports nearly 1600 jobs in the local economy

The majority of offshore particles found to date are of MTR origin and their presence is detected by b/g scintillation probes registering high gamma radiation from the decay of Cs137 DFR particles have also been found in the approximate ratio of 16 DFR MTR DFR particles are more fragile Surveys of the foreshore at Dounreay and the neighbouring beach at Sandside have been carried out fortnightly and after storms Despite regular surveys of local beaches as far afield as Thurso, no other particles have been found on public beaches This suggests the particle problem is localised to the immediate Dounreay environs

During its long history, various incidents at Dounreay could have led to particles being accidentally discharged and these have been openly discussed, documented and made available to relevant parties

LOCAL ACTIVITY

In 1995, Applled Research and Technology of Inverness sited their prototype wave powered generator, OSPREY 1, some 350 metres from the coast at Dounreay The two primary reasons for this location were the proximity to the National Grid system at Dounreay for the export of electricity and the replicability of the wave forms Unfortunately, this 20 m x 20 m x 18 m structure started to break up within a few weeks of its installation The following year, the contract was let to Fathoms to undertake the salvage of this structure

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