Nondestructive Assay Measurements in Support of IIEU Suspension at the Portsmouth Gaseous Diffusion Plant

Production of highly enriched uranium at the Portsmouth Gaseous Diffusion Plant is being suspended. Nondestructive assay measurements are being conducted in support of the HEU Suspension Project to meet criticality safety and safeguards requirements. The measurement approach is to perform passive neutron and gamma-ray measurements from outside the equipment enclosures to quantify residual uranium deposits contained in each piece of process equipment scheduled for shutdown. Additional measurements will be performed from inside of the enclosures for all pieces of process equipment which exceed threshold quantities. High-resolution gamma-ray measurements are performed to determine 235U enrichment and 234U concentrations. A locate and quantify method is used to measure process piping. Gamma-ray scanning is used to locate deposits exceeding a threshold value and a combination of gamma-ray and neutron measurement methods are used to quantify residual deposits.