First intercomparison among laboratories involved in COST Action-TU1301 'NORM4Building': Determination of natural radionuclides in ceramics

摘要

This work describes the outcomes of the COST Action-TU1301 "NORM4Building" intercomparison on the determination of natural radioactivity in ceramics. Twenty-two laboratories involved in the intercomparison are evaluated for their performance using robust statistics. The reference values of Ra-226 (Bi-214 and M-214) are determined to be 122 +/- 11 Bq kg(-1) and 124 +/- 14 Bq kg(-1), respectively and in secular equilibrium in the uranium chain while the reference values of Th-232 (Ac-228) is determined to be 61 +/- 6 Bq kg(-1) and that of K-40 was determined to be 955 +/- 40 Bq kg(-1). Although the aim of the exercise was to determine the activity concentration of Ra-226, Th-232 and K-40 and evaluation of the "Activity Concentration Index", laboratories were asked to report complete characterization of natural radionuclides. The results of this exercise pointed out a good performance among laboratories since the percentage of the acceptable results were above 90% for the radionuclides of interest. Based on these results, considering the systematic rejection of the results reported from a few laboratories we emphasize the need for quality control procedures. (C) 2016 Elsevier Ltd. All rights reserved.