Certified Reference Materials For Radiometric Safeguards Analytical Measurements: - A Demanding Issue-

Assay techniques for nuclear materials based on active or passive radiometric measurements are getting increasing used for a number of practical reasons, particularly in analytical laboratories performing a substantial portion of routine analytical work on those materials. The reference materials required for calibrating these techniques differ in a number of parameters distinctly from the traditional types of reference materials produced for classical (chemical) analytical methods. Therefore the creation of a certified reference basis for the radiometric techniques represents a demanding task and challenge. The differences relate both to physical parameters such as amount and composition, and the the quantities to be certified in addition, viz, density, effective mass of 240Pu etc. The present paper outlines the specific requirements for certified reference materials in view of their practical application and with regard to generic characteristics. It further describes the efforts so far undertaken to create a reference basis for the radiometric methods, ant it points to some problems still existing in this area.