Hottest radiocactive spot so far turns up at Sandside
A PIECE of radioactive fuel with potentially "significant" health risks has turned up on a beach in Caithness.
Dounreay Site Restoration Ltd (DSRL) confirmed on Monday that it had recovered a particle – thought to have originally come from the Prototype Fast Reactor – from the water’s edge at Sandside beach in Reay.
If confirmed by further testing it will be the first time a radioactive speck of this category has been discovered on public land locally – with its unusual chemical make-up also raising questions.
DSRL’s head of communication Colin Punler explained that it has informed the Scottish Environment Protection Agency that additional tests are being carried after it was noted that the particle was twice as "hot" as the previous highest find since beach monitoring started nearly 20 years ago.
"It has been predicted for a number of years that we were likely to find one at Sandside so in that sense it is not a surprise," said Mr Punler.
"The surprising thing about this particle is the chemical make-up of it."
The particle – around the size of a grain of sand – was picked up last Tuesday during routine monitoring of the area.
Checks carried out on the beach indicated the particle had a higher than normal beta dose rate, believed to be coming from the high concentration of radioactive isotope strontium,
"Normally you find an equal amount of strontium to caesium – if you find a 1000 units of caesium then you would expect to find 1000 units of strontium," said Mr Punler.
"In this case there were around 1000 units of caesium and somewhere between one and two million units of strontium."
This means the particle has the status of "significant".
Particles are classified by potential health effects if a human came into contact with one either on the skin or by swallowing or breathing it in. They are grouped into three categories – minor, relevant and significant.
"Significant" particles have been found before offshore and on the foreshore at the Dounreay site itself, but this is the first time one of this category has been found on public land.
It is the 208th particle to be found on the beach.
"Tests will now be done to dissolve the particle and separate the different parts to get a fully accurate measurement of the radioactivity," said Mr Punler.
"Strontium is the main radiation source in this particle and emits beta radiation which takes longer than usual to get a true and accurate measure of the hazard.
"That’s why the results we have at the moment are provisional.
"The presence of niobium-94 in the particle indicates it was originally from fuel that was burned in the Dounreay fast reactor," explained Mr Punler. "Why the ratio of caesium to strontium is so different in this particle we don’t know. The tests that we do on it may shed more light on it."
The beach at Sandside is around 3km west of the redundant nuclear site.
Meanwhile, work is due to resume in May to clear particles from the seabed near the site.
More than 1800 have been recovered so far from the seabed where there is evidence of a "plume" from historic effluent discharges dating back 50 years.