The latest in a series of radioactive particles has been discovered on a public beach, prompting calls from environmental campaigners for the growing problem to be independently investigated.
The particle was found on Sandside beach, two miles from Dounreay nuclear plant in the north of Scotland on Friday. Since monthly inspections of the beach started in September, particles have been found at a rate of one a month.
A spokeswoman for the plant said it was around the size of a grain of sand and initial investigations suggested it was similar in type and characteristic to those discovered previously. The spokeswoman stressed there was little danger to members of the public and that any health risks were tiny. The particle is now being analysed.
Lorraine Mann of Scotland Against Nuclear Dumping (Sand) said: "This can't be allowed to continue. It's been going on for the last 17 years. Somebody has to take the investigations out of the hands of the UKAEA because they are absolutely useless.
"Some of these particles are so radioactive that if they were swallowed, say in a sandwich, they would burn a hole right through your guts.
"Dounreay is quite right to say that the chances of people coming into contact with the particles is very, very small. But so are your chances of winning the lottery - and people do win." She added that she was also concerned about the latest find because the tourist season would start soon with larger numbers of people than usual visiting beaches in the area. "It surely can't be right that these particles are turning up where people are," she said.
In February, after the ninth particle was found, environmental campaigners called for a full investigation into the safety of the plant, run by the UKAEA, which has announced a multi-million pound package of improvements at Dounreay.
The UKAEA has come under fire on more than one occasion over health and safety at the site.
In 1998, a report produced by the Health and Safety Executive and the Scottish Environmental Protection Agency said weak management was responsible for "chronic safety problems" there. And last month, the UKAEA was fined £101,000 after pleading guilty to a series of safety breaches.
It admitted three charges of contaminating workers with excessive doses of radiation in 1995, and a separate charge relating to safety at the plant when a contractor accidentally dug through a main power cable.