ROLLS-ROYCE is under investigation by the Health and Safety Executive because it temporarily lost a potentially dangerous radioactive substance.
After a Freedom of Information request from a member of the public, the executive revealed it had issued an improvement notice to the firm and that an investigation was in progress.
The incident, which took place in March 2011 at the firm's Sinfin Lane-based Marine Power Operations, involved what the Guardian newspaper described as "small pellets of extremely radioactive ytterbium-169".
Asked for confirmation of this information, a Health and Safety Executive statement said the material was a "sealed radioactive source", which are usually "encapsulated in steel and are designed to ensure that the radioactive substance cannot be released from the source capsule to prevent the spread of radioactive contamination".
It said the Rolls-Royce example was of a type that are sources of "high radioactivity" and used for "irradiation and industrial radiography".
The statement said: "These can present a very significant risk of injury or death to persons exposed even for a relatively short time.
"The investigation of this case is open and active."
The executive was yesterday unable to give further details of progress with the investigation or what the improvement notice required.
A Rolls-Royce statement said it was "a matter of public record that an incident took place in Derby in 2011 from which lessons have been learned and safety standards further strengthened". It added: "This process of continual improvement is common across the industry."
The executive said that its "full range" of enforcement options were considered when radioactive substances were lost, released or stolen.
Its statement added: "Enforcement action is always a consideration up to and including prosecution but the final decision on action will depend on a number of factors including, in the case of prosecution, the likelihood of securing a conviction and the public interest."
The Freedom of Information response revealed that radioactive materials had gone missing from businesses, hospitals and even schools over the past decade.
chris.mallett@derbytelegraph.co.uk