RESULTS OF THE TENTH INTERNATIONAL INTERCOMPARISON OF ENVIRONMENTAL DOSIMETERS

The tenth in a series of international intercomparisons of environmental dosemeters was held at the Idaho National Engineering Laboratory from December 1992 to April 1993. One hundred and two participants from 27 countries submitted 158 dosemeter sets for exposure to natural environmental radiation and a laboratory Cs-137 source. The field conditions were unusually harsh, with temperatures ranging from -32.8 to + 12.8 degrees C, snow accumulating up to 76 cm, and winds reaching speeds of nearly 22 m.s(-1). The field dose rate was measured independently by pressurised ionisation chambers, and the laboratory exposures were verified by The National Institute of Standards and Technology calibrated transfer chambers. Overall, the performance of most dosemeters was quite good, with 90-97% of the participants reporting within 30% of the delivered dose for the field and laboratory exposures. For similar dose levels, performance was about the same for both field and laboratory exposures. Calculations of the overall bias and standard deviation for each dosemeter set indicated that 93% of them would pass a performance criterion (tolerance level of 0.5) which is presently under consideration for the new ANSI standard on environmental dosimetry testing.