This question already has an answer here:
The 2019 miniseries "Chernobyl" appears to state that the "lava like" substance of melted radioactive matter from the core, the so-called "corium", could eat its way down into the water reservoirs below the reactor core. This could then possibly cause a second, much stronger explosion.
They indicated this could be on the orders of several megaton, I believe 2-4.
This seems to be on the order of a hydrogen bomb, and I'm curious if this is factually accurate. If it is factually accurate, how exactly is such explosive force possible? Was it assumed fusion would take place? How would the required pressure for fusion be achieved, and why would not fizzling (the explosion itself starting and immediately pushing away the material so no very significant explosion would take place) be an issue for such a large explosion?
I see this topic relating to the miniseries turns up on sites such as ArsTechnia and Reddit, but I'm curious what the community here has to say about it.
Any sources that can be cited would be great.