Assessment of uranium content in the lungs of nuclear fuel workers at AB ASEA-ATOM

Abstract

A method has been developed for analysis of the pulse height distributions from thorax measurements on uranium workers. It takes into consideration the very few and low energy gammas emitted from uranium. Four Planar HpGe detectors 2000 mm² × 10 mm, are used. By choosing predetermined energy intervals for the peaks and the surrounding background, the statistical errors are minimized to give an acceptable lower level of detection when ordinary computer assisted peak search programmes do not work. The MDA of an individual measurement is approximately 2.0 Bq U-235. All pulse height distributions are stored on floppy discs by the use of a PDP 11/2 computer on line with the MCA. It is possible to add different measurements to achieve an average MDA for a group of people just above the background and to assess bodyburden differences which cannot be seen in a single 40-minute measurement. The results from the first year of operation will be presented along with the method and the specially designed counting room.