3-D Heat Signature Simulation Results for Safeguarded Spent Nuclear Fuel - 23481

The use of civilian nuclear power often leads to a rise in nuclear proliferation concerns. As a result, there is an increase in demand for advanced spent nuclear fuel (SNF) safeguarding methods. One method currently being studied is the detection of heat signature generated by SNF. For this method, an SNF assembly is imbedded in borosilicate glass, forming an SNF package that is encapsulated within a double metal canister. The amount of heat signature generated is simulated by calculating the temperature profiles using computational simulations. A thermal camera is used to record the heat signature emitted by the SNF. So far, computational work regarding this method has been performed. Among the computational work includes simulations of 2-D storage models, for which results were presented at the 2021 and 2022 Waste Management (WM) Symposia Conferences. The 2-D simulation results have paved the way for conducting 3-D simulations of the same SNF storage configurations. So far, 3-D simulations were conducted for two SNF storage models consisting of a single spent fuel rod, with varying amounts of imbedding glass, to calculate the axial and radial temperature profiles. For this SNF storage model, the maximum temperatures located at the top-center of the configuration with a 76% glass composition, are approximately 433.17 K and 435.76 K for models 1 and 2, respectively. The glass surface temperatures, meanwhile, are approximately: i) for model 1, 432.34 K and 405.31 K at the top and bottom, respectively ii) for model 2, 434.93 K and 405.53 K at the top and bottom respectively. These results were expected since cooling air is vertically flowing along the surface of the outer canister from the bottom upwards. As the cooling air moves further upwards, it absorbs heat along the way, reducing the cooling capabilities of the air. Thus, hotter temperatures will occur in the upper regions. 3-D simulations for a single spent fuel rod will allow us to work our way towards simulating the storage of multiple SNF, for which the temperature profile will also be calculated. This is a crucial step in the development of a reliable heat signature computational simulation for safeguarded spent nuclear fuel. (authors)