Rolls-Royce Marine Power Operations has been fined £200,000 and ordered to pay £176,500 in costs for losing a capsule the size of a small screw for about five hours.
The capsule, a radioactive source containing ytterbium–169, was being used at the company’s Sinfin Lane site in Derby to test welds. The loss of the capsule resulted in a number of workers being exposed to high levels of gamma radiation.
Leicester crown court heard that at around 5am on 3 March 2011 the source was being used in a purpose-built radiography enclosure, but during the work the capsule became detached from its holder, ending up inside the component being tested.
This went undetected because at the end of the test a green light indicated that the radioactive material was back in its sealed container. The loss was discovered only when three welders who later worked on the component spotted the capsule and removed it for examination, passing it around.
A radiographer also handled the capsule before identifying the object as a radioactive source. The room was cleared at around 10am, and the radioactive source was recovered.
A joint investigation by the Health and Safety Executive and the Environment Agency found the workers’ hand exposure to radiation was considerably in excess of the annual permitted dose of 500 millisieverts.
In some cases, it was exceeded by up to 32 times the permitted amount. The regulators also discovered a number of procedural failings, including the failure to do a suitable and sufficient risk assessment for the gamma radiography work at Sinfin Lane, and a lack of training for personnel.
In addition to breaches of health and safety legislation, the company, a subsidiary of Rolls-Royce plc, pleaded guilty to three counts of contravening Regulation 38(2) of the Environmental Permitting Regulations 2010, which covers non-compliance with permit conditions. Rolls Royce Marine Power Operations has since put safety measures in place to prevent a similar incident occurring.
Commenting on the case, Mark Haslam, area manager for the agency, said: “The most important thing is that the company has learnt the lessons from this and put improvements in place to ensure this does not happen again. Our overriding aim in regulating the use of radioactive materials is to ensure their safe management and control to protect the public and the wider environment from the harmful effects of radiation.”