Is your proposal basically to burn away nuclear waste? Why is the gasoline important?
Few issues I see:
I don’t think such waste can be disposed safety by incineration. Because if it could, we’ve have done so already. It’s probably the go to solution when it comes to waste disposal, apart from just burying it or dumping it in the ocean.
The main problem is the safety and handling of such radioactive waste. You do not want it anywhere near people and that’s why it’s isolated. They are highly dangerous. Do you want such a substance sitting in your vehicle, garage, gas station with high traffic, etc? The radioactive substance doesn’t just go away when you add gasoline to it.
Even assuming we can get past the safety issues, the said mixture will likely not work in vehicles at all, or would destroy your engine.
How would this reduce carbon emissions? You are still burning gasoline except it’s radioactive gasoline.