A subsidiary of engineering giant Rolls Royce has been forced to pay out over £375,000 after workers were exposed to high levels of gamma radiation when it lost a radioactive source at its Derby plant.
Leicester Crown Court heard that significant failings led to the radioactive source – a capsule the size of a small screw – containing Ytterbium -169 being lost for approximately five hours at the Sinfin Lane site.
Rolls Royce Marine Power Operations, which manufactures components for nuclear submarines, uses radioactive sources in their industrial radiography work to test that welds are perfect.
“Gamma radiation emitted by this type of radioactive source is harmful to human health,” said David Orr, HSE’s specialist inspector of radiation after the hearing. “Rolls Royce is fully aware of the danger it poses and has a clear duty to protect staff from harm. However the company failed its duty of care on this occasion, losing control of the source without realising it.”
At around 5am on 3 March 2011 the source was being used in a purpose-built radiography enclosure. During the work the capsule became detached from its holder, was lost out of the end of the guide tube and ended up inside the component being tested. The loss of the source was not detected by the safety features of the radiography enclosure or by the radiographer in charge of the work.
The source was only discovered when welders subsequently working on the component in the clean room spotted the capsule and retrieved it for examination, passing it among themselves without realising what it was.
When the radiographers returned for their next shift, and after some initial confusion that saw them directly handling the capsule, they correctly identified the object as a radioactive source. The room was cleared, the radioactive source recovered and the area made safe.
The subsequent investigation by HSE 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 the permitted amount was exceeded by up to 32 times.
The court was also told how inspectors found the company failed to ensure that a suitable and sufficient risk assessment was in place for the gamma radiography work carried out on site.
Inadequate procedures together with deficiencies in training led to Rolls Royce Marine Power Operations Ltd failing to ensure that robust and effective controls were in place to manage the risk of using high activity radioactive sources.
Additionally, the capability of the radiation monitoring equipment was not well understood and failed to detect where the radioactive source was at all times which is an essential requirement when carrying out radiography work.
Rolls Royce Marine Power Operations Ltd, of Moor Lane, Derby, was fined £200,000 and ordered to pay costs of £176,500 after pleading guilty to breaching sections 2(1) and 3(1) of the Health and Safety at Work Act 1974, regulation 3(1)(a) of the Management of Health and Safety at Work Regulations 1999, regulation 11 of the Ionising Radiation Regulations 1999 and three counts of breaching regulation 38(2) of the Environmental Permitting Regulations 2010.
Orr added: “Industrial radiography carries a greater risk of radiation exposure compared to other industrial uses of radioactive sources by nature of the very high activity sources used. HSE expects companies carrying out such work to have robust safety systems and procedures in place to protect employees during normal work and following a radiation accident such as the detachment of the radioactive source.
“There was no effective surveillance of it for five hours and the exposure of workers to radiation, including some who were not involved in the industrial radiography work, was considerably in excess of the annual permitted dose.”
Mark Haslam, area environment manager for the Environment Agency, said: “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.
“For us, 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.”
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