Dounreay today publishes the findings of its investigation into the discovery of a radioactive particle in land adjacent to the licensed site.
An investigation was carried out into the discovery of contamination during a survey last month of the off-site area designated for development as a repository for low level radioactive waste from the site decommissioning.
One find was determined to be a "minor" DFR particle and the second was found to be a disperse area of radioactive contamination containing caesium.
From expert advice neither of the finds poses a health risk.
Both of the finds were well below the ground surface indicating they have been there for 10 years or longer.
The reason for the contamination at this location was not definitively determined.
The particle may have been windblown from a nearby landfill used in the past by Dounreay, the site or the sea.
During strong winds, the caesium contamination may have come from the FCA stack. It has a similar activity to spots of contamination occasionally found on site.
Foods Standards Agency Scotland examined the results and confirmed they do not raise any food safety concerns. In the event of further contamination being found, the agency said it would consider re-assessing the food chain risk.