RESULTS OF THE 1993 INTERLABORATORY COMPA RISON ON THE DETERMINATION OF GAMMA-RADIONUCLIDES AND SR-90 IN GRASS POWDER

Following the accident in Chernobyl in 1986 the number of units availa ble for monitoring radioactivity, mainly for gammaspectrometry, has be en increased considerably in the Federal Republic of Germany. Furtherm ore, new legislation requires that all official monitoring laboratorie s verify the quality of their analytical technique by participating in interlaboratory comparison studies organized by Federal institutions. Such a study was therefore organized in January 1993 by the Institute of Chemistry and Physics at the Federal Dairy Research Centre in Kiel . 81 laboratories collaborated on the analysis of Cs-137, Cs-134, K-40 , and Sr-90 in grass powder. This paper describes the statistical eval uation of 119 sets of data for Cs-137, Cs-134, K-40 and 33 sets of dat a for Sr-90. The results of the study were good as expected. After eli minating only a few discordant data, the average deviation of the labo ratory means from the overall mean was 4.1% for Cs-137, 3.6% for Cs-13 4, 4.3% for K-40, and 11% for Sr-90. Such good results imply that effi cient and sophisticated equipment and software are available to be ope rated by experienced personnel.