Analysis of a UF6 Thermal Mass Flow Meter: A New Safeguards Tool for Gas Centrifuge Enrichment Plants

摘要

Gas centrifuge enrichment plants (GCEPs) can be used to produce fuel for nuclear weapons. In order to do this, significant changes in the flows of uranium hexafluoride (UF_6) inside the centrifuge pipes are required. Goldston, et al. previously presented a concept for a non-invasive thermal mass-flow meter (TMFM) to provide unattended real-time monitoring of such flows. [1] The concept is based on providing heating and cooling in separate locations along a pipe carrying UF_6 gas, and determining the power required to maintain a specified temperature gradient along the pipe. In this paper, we use Gnielinksi's correlation to estimate the heat flow between the pipe walls and the turbulent gas flow inside. Initial time-independent results are obtained with vastly decreased computational requirements compared with CFD calculations, and they are in sufficiently good agreement with the more detailed ANSYS CFX studies to justify using this approach to examine time-dependent phenomena. This allows for efficient study of a feedback technique to improve time-response, and then the development of an optimized heating and cooling profile to improve the accuracy and optimize the time response of the system. Moreover, we are able to determine the resistance of the system to spoofing through heating or cooling the UF_6 gas relative to the pipe, in advance of its entry into the measurement section.