This is the first time I hear this idea to use convergent boundaries to bury anything. It's interesting! However, to my layman understanding, when discussing nuclear waste we need to be precise. If the containers break or leak in an undesirable place (or depth) without us having any access to it or being able to fix it, I imagine it could become quite the catastrophe. And the pressure and sheer power tectonic plates can apply, to my understanding, far exceeds anything we can build. So how is it possible to safely bury radioactive waste in convergent boundaries?