Scotoil Services Ltd, a company which disposes of radioactive waste from the North Sea oil industry, inadvertently pumped dangerous particles into Aberdeen Harbour over several months.
The pollution included materials such as lead-210, radium-226 and radium-228, which both glow blue in the dark, and polonium-210, which was used to poison the former Russian spy, Alexander Litvinenko.
An investigation by the Scottish Environment Protection Agency (Sepa) found one “gross” breach and several “major” breaches of the firm’s operating conditions.
However, the public was never told about the leak, which continued unchecked from November 2011 until April 2012, and it also appears that the Scottish Government was not informed either.
The revelation comes just weeks after the UK Defence Secretary, Philip Hammond, faced severe criticism over his handling of a “minor” leak at a nuclear test reactor, at Dounreay, in January 2012.
This incident, which led to a 10-fold rise in radioactive emissions, was only made public last month, although the Ministry of Defence did inform Sepa in the autumn of that year.
In response, First Minister Alex Salmond wrote to Prime Minister David Cameron accusing him of “disrespecting the people of Scotland”.
While Scotoil had installed equipment to remove solid material from their liquid effluent, in April 2012, they informed Sepa that a final filter they were using had potentially failed
Sepa said in a statement Scotoil has long been at the centre of concerns about radioactive particles washing up on the southern end of Aberdeen Beach, known as Foot Dee.
Drilling for oil and gas causes Naturally-Occurring Radioactive Material (NORM) to build up on offshore equipment – an estimated 50 to 100 tonnes each year from the North Sea alone.