Effects of Bubble Injection on Heat Transfer from a Volumetrically Heated Sulfate Salt Solution

The fissioning of uranium in an aqueous solution creates ⁹⁹Mo, the precursor to ^99mTc, but also generates large amounts of hydrogen and oxygen from the radiolysis of the water. When the dissolved gases reach a critical concentration, bubbles will form in the solution, affecting both the fission power and the heat transfer out of the solution. Magnesium sulfate (MgSO₄) was chosen as a surrogate for uranium sulfate salt in an aqueous solution for the experiments. A high aspect ratio tank was constructed to measure heat transfer from the solution with internal gas and heat generation. A fritted glass air injection manifold allowed the exploration of bubble characteristics and flow patterns on heat transfer from the heated pool to the cold walls. Experimental data analysis provided heat transfer coefficient values as a function of axial position, power density, and the superficial gas velocity in the pool. Results, including a recommended correlation for average heat transfer coefficients, are provided for superficial gas velocities between 0 and 0.3 cm/s and power densities of 200 and 400 W/L in pH 7 and pH 1 MgSO₄ solutions.