Interlaboratory comparison program for nondestructive assay of prototype uranium reference materials

The US Department of Energy (DOE), New Brunswick Laboratory (NBS), designed and administered an interlaboratory comparison program based on the measurement of NBL-produced prototype uranium nondestructive assay (NDA) reference materials for scrap and waste. The objectives of the program were to evaluate the reliability of NDA techniques as applied to nuclear safeguards materials control and accountability needs and to investigate the feasibility of providing practical NDA scrap and waste reference materials for use throughout the nuclear safeguards community. Fourteen facilities representing seven DOE contractors, four US Nuclear Regulatory Commission (NRC) licensees, one EURATOM Laboratory, and NBL, participated in this program. Three stable, well-characterized uranium reference materials were developed and certified for this program. Synthetic calcined ash, cellulose fiber, and ion-exchange resin simulate selected uranium scrap and waste forms which are often encountered in fabrication and recovery operations. The synthetic calcined ash represents an intermediate density inorganic matrix while the cellulose fiber and ion-exchange resin are representative of low-density organic matrices. The materials, containing from 0 to 13% uranium enriched at 93% 235U, were sealed in specially selected containers. Nineteen prototype reference samples, plus three empty containers, one to accompany each set, was circulated to the participants between August 1979 and May 1984. Triplicate measurements for 235U on each of the 19 filled containers were required. In addition, participants could opt to perform modular configuration measurements using containers from Sets IIA and IIB to simulate non-homogeneously dispersed uranium in waste containers. All data were reported to NBL for evaluation