Application Research Of Uranium Attributes Determination By Gamma Ray Spectroscopy In Nuclear Safeguards

Determining attributes of uranium samples by Y -NDA(Non Destructive Assay) methods is important activities in MC&A system and routine safeguards inspection. The algorithm and applicability of MGAU7U235, which is a code used for uranium enrichment determination, have been discussed in this paper. A method of uranium enrichment measurement was researched for samples, in which equilibrium between ~238U and its decay daughter Th was not reached. A new method for HEU age-dating has been developed.MGAU/U235 is a code used for uranium enrichment measurements. Its algorithm and applicability have been discussed in this paper. Uranium samples with different shape and different enrichment were measured by HPGe detector, then were analyzed with the program. The main problems of uranium determination were studied. Experimental results of five certificated reference samples indicate that the enrichments can be determined within 3% uncertainty in case of good resolution and reasonable dead time.Before ~238U is equilibrium with ~234Th, the deviation of analytical results will be more than one hundred percent using current methods. In this work, two uranium samples (one is nature uranium, another is depleted uranium) were prepared without decay daughters of ~238U. From discontinuous measurement in six months, proper results were given by using corrected separate time. The uncertainty of uranium enrichment was less than 10%.Uranium Age is defined as the time internal since the decay daughters were eliminated from the uranium-containing material to the measurement. The HEU age is determined by measuring quantitatively the activity ratio of ~234U and its decay daughter ~214Bi, which was newly reported. In this work, a new method has been developed and the relative deviation of HEU age is less than 15%.