The company would be looking at it as a by-product of the nuclear process. Kind of like using waste heat to keep the building warm and powered through the use of nuclear power. Since you’re using nuclear power anyway, those costs are set. However, with a minimal set-up, you could also be turning mercury into gold.
I’m not sure if that is a wise policy, because we may eventually find some process that needs mercury and results in mercury becoming more valuable than gold.