URANIUM ENRICHMENT MEASUREMENT BY X-RAY AND GAMMA-RAY SPECTROMETRY WITH THE URADOS PROCESS

The methods used for: the uranium enrichment measurement require in ge neral prior instrument calibration with several standards. Thus, it is possible to avoid the constraints involved in calibration by consider ing the complex spectral region called XKalpha. This spectral region i s sufficiently limited so that the variation of the detector efficienc y response is small enough to facilitate a self-calibration. Processin g this region is critical and requires taking into account 3 elemental images, one corresponding to U-235, one to U-238 and one to the X-ray fluorescence induced in the sample by radiation above 100 keV. A proc ess called ''URADOS'' based on this principle has been developed. Six uranium oxide standards with different enrichments and infinite thickn esses were counted several times to test this process; other samples, some highly enriched, were also used. The results obtained are compare d to the declared values. From these measurements, it has been possibl e to improve the photon emission probability values. (C) 1998 Elsevier Science Ltd. All rights reserved.