Enrichment Assay Methods Development for the Integrated Cylinder Verification System

Abstract

International Atomic Energy Agency (IAEA) inspectors currently perform periodic inspections at uranium enrichment plants to verify UF 6 cylinder enrichment declarations. Measurements are typically performed with handheld high-resolution instruments on a statistically determined sampling of cylinders taken to be representative of the facility's entire product-cylinder inventory. Pacific Northwest National Laboratory (PNNL) is developing a concept to automate the verification of enrichment plant cylinders to enable 100 percent product-cylinder verification and potentially, mass-balance calculations on the facility as a whole (by also measuring feed and tails cylinders). The Integrated Cylinder Verification System (ICVS) could be located at key measurement points to positively identify each cylinder, measure its mass and enrichment, store the collected data in a secure database (mailbox), and maintain continuity of knowledge on measured cylinders until IAEA inspector arrival. PNNL's ICVS concept uses measurement systems that can be operated in an unattended mode: medium-resolution scintillators for gamma-ray spectroscopy and moderated He-3 neutron detectors. Prior proof-of-principle studies of advanced nondestructive assay (NDA) methods for automated enrichment assay, particularly neutron-related signatures spawned by U-234 alpha emission, have encouraged further development of NDA methods suitable for an ICVS prototype. The work described in this report was supported by NA-243 funding in late FY09, following completion of the initial PNNL Laboratory Directed Research and Development (LDRD)-funded study that focused on non-traditional NDA signatures. A proposal has been submitted to NA-241 for design and testing of a prototype ICVS that utilizes both non-traditional and traditional NDA signatures. Work on the components of the ICVS that do not involve research and development will continue to be supported under NA-243, and are addressed in separate reports. The three main objectives of this FY09 project are summarized here and described in more detail in the report: 1) Develop a preliminary design for a prototype NDA system, 2) Refine PNNL's MCNP models of the NDA system, and 3) Procure and test key pulse-processing components. Progress against these tasks to date, and next steps, are discussed. v