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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Deep geologic repository progress—2025 Update
Editor's note: This article has was originally published in November 2023. It has been updated with new information as of June 2025.
Outside my office, there is a display case filled with rock samples from all over the world. It contains a disk of translucent, orange salt from the Waste Isolation Pilot Plant near Carlsbad, N.M.; a core of white-and-bronze gneiss from the site of the future deep geologic repository in Eurajoki, Finland; several angular chunks of fine-grained, gray claystone from the underground research laboratory at Bure, France; and a piece of coarse-grained granite from the underground research tunnel in Daejeon, South Korea.
Sayed A. El-Mongy, Kh. A. Allam
Nuclear Technology | Volume 205 | Number 11 | November 2019 | Pages 1474-1479
Technical Paper | doi.org/10.1080/00295450.2019.1593012
Articles are hosted by Taylor and Francis Online.
Precise assay of uranium enrichment without time-consuming analysis is a crucial factor in nuclear safeguards process. This paper aims at a computational development using innovative Monte Carlo (MC) method for 235U mass enrichment (%E) verification for the UF6 cylinder. This new approach focuses mainly on using different UF6 physical properties (effective volume and density) and extra 235U gamma- and X-ray transitions as input parameters for efficient calculations of %E assay. In this work, we used the measured values of the dose rate (μSv/h) due to the emitted gamma- and X-rays of 235U content at the cylinder external surface for enrichment calculations. The attenuation of the main 235U gamma- and X-energies due to the cylinder wall (5B-Type Ni Inconel alloy) was also estimated to wide range of energies using XCOM: Photon Cross Sections Database software. Using this suggested model for 235U enrichment calculation, the calculated value of 19.46 ± 1.28% is within one standard deviation of the certified value of 19.75 ± 0.40%. The mass of 235U was also estimated and found to be 2.6814 kg. Based on this improved approach, the total uranium activity of the investigated UF6 cylinder was calculated and found to be (5.52 GBq), which is 98.6% from the declared activity value (5.6 GBq). These accurate and confident calculated values are direct functions in the improved parameters and the developed MC code.
