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Simulation of Isotopic Concentrations and Gamma Spectra from Dynamic Fission Sources...

by Sean E O'brien, Gregory T Westphal, Michael P Dion, Logan M Scott, Karen K Hogue
Publication Type
Conference Paper
Journal Name
Proceedings of the INMM & ESARDA Joint Virtual Annual Meeting
Book Title
Proceedings of the INMM & ESARDA Joint Virtual Annual Meeting 2021
Publication Date
Page Numbers
1 to 10
Publisher Location
New Jersey, United States of America
Conference Name
INMM/ESARDA Joint Virtual Annual Meeting 2021
Conference Location
Vienna, Austria
Conference Sponsor
Institute of Nuclear Materials Management
Conference Date

A tool was developed to rapidly generate synthetic gamma-ray spectra to evaluate safeguards material control and accounting methods for liquid-fueled molten salt reactors. Molten salt reactor operations pose unique challenges to nuclear safeguards methods and protocols compared to deployed reactors designs (e.g., light water reactors). This research evaluates the use of gamma-ray spectroscopy to monitor fission product isotopic flow through a reactor model to understand expected operations and investigate changes to the spectra with material diversion scenarios. The large design space of molten salt reactors (e.g., liquid-fueled, liquid-cooled, online separations) could potentially lead to many measurement points within the reactor system. The developed analytical tool generates and evaluates synthetic gamma-ray spectra from dynamic reactor simulations by extracting isotopic inventory to generate source terms. An implementation in the Gamma Detector Response and Analysis Software (GADRAS) Application Program Interface (API) uses the source terms, a model of the reactor component, a detector response function, and measurement plan to quickly generate and analyze spectra. Prospective measurements are then evaluated in the more accurate but slower Geant4 simulations. Utilization of the developed modeling tool and analysis of the subsequent spectra enables optimization of collimation, shielding requirements, and expected count rates that are used to determine key measurement points in the modeled reactor design.