Corus Redeem® detects radioactive contamination in sheep, scrap metals, landfill sites and mass transit systems

03 Sep 2007

Corus Northern Engineering Services (CNES) has supplied 40 of its Redeem® handheld radioactive detection systems to the UK’s Food Standards Agency (FSA), 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 back in the 1980s by the research and development laboratories at Corus (then British Steel) in order to prevent contaminated recycled metal from being delivered to its own steel production sites. However, the system has been re-developed, refined and improved over the last 20 years, resulting in a wide variety of new applications outside of its original intended use. CNES is now responsible within Corus for selling and supporting Redeem®.

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 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 counts are often done outside in upland weather conditions. Reliability and ease of use are also important.

Rod Crust, Business Development Engineer at CNES comments: “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 explains further: “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.”

Scrap metal, security and mass transit systems

Vehicle radiation portal monitoring systems have been in use for many years within the scrap metal industry. These systems are installed so that rogue radiation sources are detected if they become mixed up with scrap metal and can be removed prior to the melting of the scrap.

More recently, radiation portals have become increasingly important within security markets and large numbers of systems are being installed at ports and border crossings. The purpose of these systems is to prevent the illicit movement of radioactive material sources.

Redeem® can be used to check for radioactive contamination in soil and at landfill sites and for providing security at cargo ports and nuclear power plants. Potential applications for Redeem® include sports stadiums, public areas, hospitals, land fill and recycling centres, mail handling rooms, high profile office buildings, airports, bridges, border crossings, underground transport, tunnels, railway stations, power stations, shopping centres, military bases and Government buildings.

Redeem is available in two main types of system: fixed and handheld. Permanent portal Redeem® systems provide discreet, continuous detection of radioactive materials. The portal monitoring systems are supplied to monitor passing vehicles or pedestrians. Typically, the vehicle systems are installed at points of entry at ports, airports or border crossings. The pedestrian systems are used to monitor people entering or leaving ports, airports or sensitive buildings. One radiation portal monitor is capable of covering a large area access point and can be integrated with other systems for plant-wide or perimeter security. Multiple units can be used at large border crossings combined with containment and lock-down systems to secure an area in the event of detection.

When a large fixed system is impractical, Redeem® is also available as a rugged, easy-to-use handheld device. This is ideal for security screening in confined spaces, in order to pinpoint the source of radiation. Handhelds are also ideal for mobile and ad hoc security requirements. CNES’ PRM 100-C range of gamma radiation detectors is both ergonomically designed and easy to use.

The handheld devices use scintillation technology. A spectral analysis facility provides extremely high sensitivity for gamma radiation. The instrument is therefore ideal for measuring gamma-emitting radio-nuclides used in the industrial and nuclear industries around the world. The unit has a large graphical display with an illuminated background, so that scanning results can be seen clearly, even in poorly lit environments.

The device has on-board memory to store measured results, which can then be downloaded to a PC, host computer or printer. Modes of operation include spectrum analysis and total counts.

Customs, police and fire departments can carry out security screening using the device. The recycling and environmental sector can use the device to identify unknown sources of radioactivity.

Whilst sheep monitoring is a rather unusual application for Redeem®, Rod Crust is clear about the technical advantages Redeem® offers and the superior support provided by CNES staff: “Our people here at CNES are fully trained engineers, who are very experienced when it comes to installing, maintaining and providing technical support for customers of Redeem. We can integrate our fixed radiation detection units into the customer’s own security systems, which might include CCTV, ANPR [Automatic Number Plate Recognition] and RFID [Radio Frequency Identification Devices] systems. We also provide location analysis and risk assessments for the client, then recommend where systems should be positioned and installed.”

In the metals recycling industry, Crust is also confident of CNES’ strengths as an organisation over other radiation detection system suppliers: “Back in the 1980s and 90s, British Steel decided that the systems it was using for radiation detection on scrap metal vehicles were simply not sensitive enough and so it began researching and developing a better system. This was when the idea for Redeem was first conceived.”

“The system developed used crystal scintillators and was around 60% sensitive, whereas the existing detectors other companies were using operated at around 20% sensitivity. When gamma radiation gets inside scrap metal, it gets attenuated so the signal is weaker. Having detectors at the side of vehicles is not enough. So Corus placed detectors at the sides, top and bottom of the vehicle, all around the load, in order to improve the overall sensitivity of the system and provide us with a fuller energy spectrum,” explains Crust. “This also means that Redeem can identify the type of radioactive isotope, by reading the precise energy levels present in the scrap metal.”