Searching for hidden radioactive sources in the Barents Rescue 2001 nuclear emergency exercise

The international nuclear emergency exercise Barents Rescue took place in the vicinity of Boden in northern Sweden between the 12th and 20th of September 2001. The Gamma Search Cell part of the exercise was designed to test the abilities of car-borne and airborne measuring systems to quickly locate and characterise radioactive sources hidden in the countryside. The Geological Survey of Norway participated in the Gamma Search Cell with a car-borne gamma-ray spectrometer system, a field team of three persons and a remote support group of two persons situated in Trondheim. The Geological Survey of Norway team identified 16 sources and 2 small areas of Chernobyl fallout in real time. Two additional sources were identified during post processing of the data. Otherwise the team drove past 2 ''strong'' and 4 weak sources without detecting them. The remaining 9 sources were in locations not visited by the car-borne measuring system. All but two source identifications were reported to the base of operations within a few minutes of discovery. The Geological Survey of Norway's source search strategy worked well and comparatively few strong sources were overlooked in the short time allocated for searching. The measuring system proved to be extremely reliable, making approximately 140,000 measurements during 8 days of measuring in and around Boden. (author)