Radioactive sheep

Corus Northern Engineering Services (CNES) has supplied 40 of its Redeem handheld radiation detection systems to the UK’s Food Standards Agency (FSA). The devices will be used for monitoring radioactivity levels in sheep in Cumbria, Scotland and North Wales, which were contaminated as a result of the Chernobyl nuclear accident.

Redeem, a system for detecting radioactive isotopes, was originally developed in the 1980s by the research and development laboratories at Corus (formerly British Steel) in order to prevent contaminated recycled metal from being delivered to its own steel production sites.

The Food Standards Agency (FSA) is responsible for food safety throughout the UK. Following the Chernobyl accident in 1986, radiocaesium was deposited over parts of the UK, in particular, relatively higher levels fell on upland areas of Cumbria, North Wales and parts of Scotland. The soil in these areas is predominantly peat-based, with high organic and low mineral content that is unable to bind the caesium and so making it available for uptake by herbage.

Since Chernobyl, the sheep grazing on these upland areas have been monitored for levels of caesium and there are still restrictions in force today on the movement, sale and slaughter of these sheep. Since its formation in April 2000, the FSA has had responsibility for managing and monitoring the sheep in these affected areas of the UK. In order to measure the radiation levels in sheep, the FSA had been using a handheld monitoring device.

Live monitoring of sheep required the holding of a probe on the rump of a cornered sheep, whilst a count of ten seconds was made. Another person simultaneously had to record the number of radiation counts whilst the ratemeter automatically reset itself. This testing procedure needs repeating three times for each sheep and the whole flock has to be tested. The device has to withstand adverse weather conditions, as testing is often done outside in upland weather conditions. Reliability and ease of use are also important.

Rod Crust, Business Development Engineer at CNES commented: ‘In 2006, CNES responded to an FSA-advertised notice in the Official Journal of the European Communities for the supply of handheld radiation devices to replace their existing units, which were nearing the end of their serviceable life. The main requirements of the new devices were that they were robust, easy to use and would provide a reliable estimate of radiocaesium concentrations in live sheep under field conditions. We secured the contract in February 2007 and have supplied forty separate handheld monitors to the FSA, along with full maintenance and QA calibration services, providing the FSA with a complete support package for their sheep monitoring process.’

CNES had to re-design its existing PRM 100-C handheld unit to make a more rugged and easier to use version for field staff, the PRM 85-C. The handle was re-designed and a special grip added to cope with slippery conditions and heavy rainfall. The display menu and software were also simplified and the weight of the PRM 85 was also reduced significantly, to make it easier for FSA staff to carry and use repeatedly.

Crust added: ‘Before securing the contract with the FSA, the PRM 85-C was put through its paces in Wales against two other competing suppliers of handhelds. The devices were all demonstrated to field staff and results were taken from sheep. The next stage involved sending the equipment to the FSA, who then used it to take field measurements on sheep in Cumbria and Scotland. We then received an order for 40 handheld devices, totalling in excess of £130,000.’