Monte Carlo Modeling Study of an Unattended Verification Station for UF6 Cylinders

Year
2016
Author(s)
Benjamin McDonald - Pacific Northwest National Laboratory
Karen A. Miller - Los Alamos Laboratories
Jonathan A. Kulisek - Pacific Northwest National Laboratory
MA Zalavadia - Pacific Northwest National Laboratory
Robert K. Weinmann-Smith - Los Alamos National Laboratory
Abstract
In recent years, the International Atomic Energy Agency (IAEA) has pursued innovative techniques and an integrated suite of safeguards measures to address the verification challenges posed by the front end of the nuclear fuel cycle. Among the unattended instruments currently being explored by the IAEA is an Unattended Cylinder Verification Station (UCVS) that could provide automated, independent verification of the relative enrichment, 235U mass, total uranium mass, and identification for UF6 cylinders processed in front-end facilities (e.g., uranium enrichment plants and fuel fabrication plants). Under the auspices of the United States and European Commission Support Programs to the IAEA, a project was undertaken to assess the technical and practical viability of the UCVS concept, which is comprised of two nondestructive assay (NDA) systems: the Passive Neutron Enrichment Meter (PNEM) and the Hybrid Enrichment Verification Array (HEVA). As a complement to the long-term field trial of the two NDA methods, Monte Carlo simulation studies were performed to characterize the neutron and gamma- ray signatures collected by PNEM and HEVA. This paper provides an overview of the MCNP models and simulation methods, benchmarking comparisons with real cylinder measurements, spatial mapping of neutron-signal efficiencies, and simulations that examine alternative detector positioning.