Experimental Results for Direct Electron Irradiation of a Uranyl Sulfate Solution: Bubble Formation and Thermal Hydraulics Studies

Abstract

In support of the development of accelerator-driven production of fission product Mo-99 as proposed by SHINE Medical Technologies, a 35 MeV electron linac was used to irradiate depleted-uranium (DU) uranyl sulfate dissolved in pH 1 sulfuric acid at average power densities of 6 kW, 12 kW, and 15 kW. During these irradiations, gas bubbles were generated in the solution due to the radiolytic decomposition of water molecules in the solution. Multiple video cameras were used to record the behavior of bubble generation and transport in the solution. Seven six-channel thermocouples were used to record temperature gradients in the solution from self-heating. Measurements of hydrogen and oxygen concentrations in a helium sweep gas were recorded by a gas chromatograph to estimate production rates during irradiation. These data are being used to validate a computational fluid dynamics (CFD) model of the experiment that includes multiphase flow and a custom bubble injection model for the solution region.

Thermal-Hydraulics Study of a 75 kWth Aqueous Homogeneous Reactor for 99Mo Production

“…The production of radiolytically produced gas bubbles in this kind of reactor could provoke an increase in the fuel solution temperature. Results presented in [19] suggest that the negative impact of the thermal conductivity of the gas phase had a significant influence on the overall temperature profiles in the AHR core. To obtain the dependence of the fuel solution temperature from the radiolytically produced gas bubbles, the CFD simulation was done using approaches discussed in Section 2.4.…”

“…Fuel solution velocity contours and velocity vectors in the central plane of the AHR core are shown in Figures 17,18,19, and 20, respectively. The average velocity of the fuel solution reached 0.016 m/s.…”

“…Unfortunately, there is insufficient data about the radiolytically produced gas bubbles to evaluate and validate the feedback introduced in the fuel solution for this variable. To reach this goal and considering the scope of this paper, the introduction of the radiolytically produced gas was studied using approaches proposed in [19]. According to these approaches, the introduction of the radiolytically produced gas was modeled as a flow of bubbles from the bottom of the structure with a flow rate equivalent to a volume fraction of 1%.…”

V&V Of CFD Modeling Of The Argonne Bubble Experiment: FY15 Summary Report

“…The CFD work in FY15 has consisted of the extension and refinement of techniques employed in the previous year. 1,2,3 Initially, two separate CFD codes, ANSYS CFX and OpenFOAM, were investigated in parallel in connection with the earlier preliminary efforts of FY14. The results from OpenFOAM, however, were found to provide greater fidelity with respect to experimental results and also allowed researchers to take advantage of all available computational resources without regard to software licensing limitations, and, therefore, all of the work presented in this report has arisen from its use.…”

“…Full details of the Argonne Bubble Experiment are described in two earlier publications. 1,2 Figures 1 and 2 are schematics of the "Bubble-Experiment Apparatus." Figure 3 is a photograph of the target vessel as set up.…”