Rapid, direct control of nuisances by uranium polluters

The gamma spectrum of dried environmental samples already contains the information on the concentration of 235U, 238U, 226Ra and 210Pb radioactivity. Evaluation has not been recommended so far because of the self-absorption of the radiation in the sample and because of inadequate calibration standards. Thanks to constant improvement processes in various sectors of gamma spectroscopy, there now seems to be a useful method for rapid and direct evaluation, which largely dispenses with chemico-physical separation processes and preparations involving high effort and cost.- Some steps towards improvement are pointed out: Optimization of the detector and measuring geometry, measurement of self-absorption by means of transmission, optimization of the calibration standard by means of transmission, simplification of corrections, choice of suitable shielding against interfering radiation.- The paper demonstrates that nuisances of uranium and its daughter products up to a detection limit of < 5 Bq/kg can be measured directly and automatically overnight almost without any cost. By extending measurements to several days, the limit of detection can be reduced to 1 Bq/kg, with an error of 0.3 Bq/kg.-These constant improvement processes furthermore open up a new field of applications such as age determinations of sediments and use of the tracer method to detect natural radioactivity. (orig.)