The JRC's Institute for Reference Materials and Measurements (IRMM) organised an interlaboratory comparison (ILC) for the determination of 15 natural and anthropogenic radionuclides in soil. A report describing in detail all the phases of this exercise has just been published.
The Euratom Treaty obliges EU countries to perform measurements of the radioactivity in their environment and to report the results to the European Commission (EC). In order to verify the performance of monitoring laboratories and to ensure the comparability of reported results, regular interlaboratory comparisons were introduced by EC. Since 2003, JRC-IRMM is responsible for their organisation.
A total of 73 laboratories (49 from EU27, 7 from associated countries, 2 from Switzerland and 15 worldwide) completed the exercise. They were nominated among those laboratories that monitor radioactivity in the environment and foodstuff by national representatives in the expert group (Euratom Treaty Art. 35/36) and by the International Atomic Energy Agency (IAEA).
The certified reference material IAEA-375 Soil (originating from the area affected by the Chernobyl accident) was used as basis for the testing material, although it was made unrecognizable for the participants. Laboratories were asked to determine the level of the activity concentration of radioisotopes of potassium, strontium, caesium, lead, radium, bismuth, thorium, uranium and plutonium (40K, 90Sr, 137Cs, 212Pb, 212Bi, 214Pb, 214Bi, 226Ra, 230Th, 232Th, 234U, 235U, 238U, 238Pu, and 239 240Pu).
The performance of the participating laboratories varied depending on the radionuclide determined and method used. Gamma-ray spectrometry of 137Cs and 40K was very successful. The determination of 90Sr proved difficult for about two-thirds of the participants, who submitted results outside the acceptable range. These laboratories need to improve their analytical procedures for 90Sr, as need several others for the uranium isotopes and 226Ra.