Chantell Murphy: Developing a New Safeguards Approach for Pyroprocessing Facilities

This is a presentation from the Union of Concerned Scientists' webinar series on nuclear weapons and global security. For a complete list of past webinars (and links to the videos), please see: https://www.ucsusa.org/nuclear-weapon...

Abstract:
Traditional International Atomic Energy Agency (IAEA) safeguards are based on nuclear material accountancy (NMA) and detection of the loss of a significant quantity of fissile material. For large throughput nuclear facilities, such as commercial reprocessing plants, it is difficult to satisfy the IAEA safeguards accountancy goals for detection of diversion. The inherent design of pyroprocessing facilities presents several challenges for applying traditional NMA and mass balance techniques making it difficult to attain low uncertainty requirements on mass balance accounting.

Several publications have demonstrated benefits from using process monitoring (PM) on nuclear facilities as a complementary safeguards measure to NMA. More recently, this concept has been expanded and preliminarily demonstrated for pyroprocessing technology. The concept of Signature Based Safeguards (SBS), being developed by the University of New Mexico and the University of Utah, is part of this expansion and is built around the interpretation of input from various sensors in a declared facility coupled with complementary NMA methods to increase confidence and lower standard error inventory difference (SEID).

One proposed safeguards solution is to track plutonium throughout a pyroprocessing facility using the nondestructive assay (NDA) method of neutron counting. The basis for this suggested approach is that curium and plutonium have very similar chemical properties in the molten chloride salts used for pyroprocessing, and Cm-244 has a very high spontaneous neutron emission rate. Measuring the neutrons from Cm-244 is sometimes referred to as the neutron balance method. Essentially, safeguarding would be implemented by verifying that the neutrons per second entering the process are equal to the neutrons per second leaving the process. If curium tracks plutonium throughout the process, the neutron balance method is a logical and accurate safeguards approach. SBS aims to couple the neutron counting method with other electrochemical process monitoring systems to detect signatures that could indicate diversion. To further advance SBS development and implementation, my work has two main components. The first focuses on validating a physics-based electrorefiner model called Enhanced REFIN with Anodic Dissolution (ERAD) with lab-scale experiments. The second is correlating electrochemical signatures of diversion derived from ERAD with the neutron balance method.

Bio:
Chantell Murphey is a PhD candidate in nuclear engineering at the University of New Mexico developing signature based safeguards for pyro-processing facilities. For the past seven years, she was a research assistant at Los Alamos National Laboratory focusing on international safeguards for new and advanced nuclear fuel cycle facilities, providing technical support to the International Atomic Energy Agency, and serving as a visiting scientist at the Forschungszentrum Jülich in Jülich, Germany applying a game theoretical approach for acquisition path analysis. She has a Master of Science in health physics from Georgetown University and a Bachelor of Science in physics from Florida State University.