Between February and March this year, 15 radioactive particles were found on the foreshore at Dounreay, an experimental nuclear site dating back to the 1950s, according to the latest government data.
The reactor was shut down in 1994 and is currently being decommissioned.
The particles contained niobium 94, which has a half life of 20,300 years, Americium-241, which has a half life of 432.2 years, caesium 137, which has a half life of 30 years, and cobalt 60, which has a half life of around 5.3 years. Eleven of the finds were categorised as “significant”, which is the highest hazard level used.
This is the highest number of particles found since 1996, when 20 particles containing caesium 137 were recorded. Fishing is banned within a two-kilometre radius of the site’s effluent outfall and nearby beaches continue to be monitored for particles.
Dourneay Stakeholder Group chair (DSG) Struan Mackie, who has held the position for three years, told ENDS: “This particle disclosure on the Dounreay foreshore represents the largest increase in some time. Although no root cause has been put forward by either the Dounreay site, or the regulators through our formal stakeholder channels, we have been assured that the matter is being investigated.
“It is important that as the interface between the site, nuclear regulators and the community, we ascertain why such an increase has happened, and whether it was preventable.
“The DSG will continue to engage with the Dounreay site on this matter and will be meeting with regulators in due course. It is important that matters such as this are open, transparent and in the public domain.”
Hundreds of particles from the Dounreay site have been found and removed since the 1980s, but monitoring work by its operator Dounreay Site Restoration Limited (DSRL) still continues. The site is regulated by the Scottish Environmental Protection Agency (SEPA) via a permit issued to DDRL) under the The Environmental Authorisations (Scotland) Regulations 2018.
The permit sets out requirements on DSRL to “use best practicable means to recover any particles detected, along with any adjacent sand that has been contaminated” and to provide a detailed report of its findings annually to SEPA.
A spokesperson for SEPA said: “SEPA is content that the monitoring and retrieval programme in place continues to provide appropriate protection for the public.
“SEPA takes advice from the Particle Retrieval Advisory Group (Dounreay) on matters related to the particles at Dounreay to support its regulatory oversight and to ensure the public and environment are adequately protected.”
A Dounreay spokesperson said: "We closely monitor the environment around the site and have seen an increase in particles found on the Dounreay foreshore this year.
"The foreshore is not used by the general public. We are looking at wind and wave data to see if we can pinpoint a trend, and will report our findings when they are complete. Safety is our number one priority and we continue to monitor the foreshore on a regular basis.
“The particles in the marine environment around the site were deposited during Dounreay’s research operations in the 1960’s and 1970’s, and cleaning up that legacy is an important part of our mission to shut down the site safely and securely, ready for its next use.”
The Nuclear Decommissioning Authority said in 2020 that it would be 2333 before the site is safe for reuse.