What about managing all radioactive waste with some sort of multiblock structures with no physical liquid/item that could be voided?
For example, for liquid waste you could build a multiblock tank that you need to attach to your reactor pipe system.
Then this tank will slowly fill up when the reactor is active but you dont need a physical fluid for that, is just a number inside the tank. If for some reason the tank is destroyed it would release a deadly quantity of radiations in a huge area.
Regarding solid waste, right know I cant figure out any idea that doesn’t involve moveable structures (like fuel rods multiblocks). Theoretically is possible to code something like that but it would be an huuuuge task.