AIRBORNE RADIATION MEASUREMENTS

The German Office for Radiation Protection an the Henschel Flugzeugwer ke GmbH, an aircraft manufacturer, in close cooperation with the Germa n Border Police developed a set of equipment for quick backfitting in helicopters to determine soil-borne contamination and trace ionizing r adiation sources from the air. Measurements of specific nuclides makin g up soil contamination are conducted by means of a computer-controlle d gamma-spectrometer with a semiconductor detector. At a flight altitu de of 100 m, this still allows soil contamination by Cs-134 and Cs-137 of a few kBq/m2 to be determined at a measurement time of 60 s (at 10 0 km/h). A 12 l NaI(Tl) detector is used to trace sources of gamma rad iation. At a sweeping distance of 300 m and an airspeed of 100 km/h, a n area of approx. 30 km2 can be scanned per hour. In this way, gamma-r adiation sources with an activity of several GBq can still be traced a t 100 m flight altitude. A GPS satellite navigation system is used for position determination. The height above ground is measured continuou sly by means of a radar altimeter. A CCD video system with a wide-angl e lens continuously records the flight path.