Buried in technical reports was this interesting plan. Researchers have developed a method to tunnel under the reactor buildings to remove melted fuel.
The plan itself bases itself in existing concepts for sealed underground tunnel systems similar to the BART train system in the US or the Channel in the UK. Japan has a similar tunnel system used for rail lines that run between the main island of Honshu and Hokkaido.
TEPCO has attempted to continue presenting a narrative that the melted fuel remained in the reactor vessels or at least remained in the containment vessels, making it more straightforward to remove. This new plan assumes fuel to have melted deeply down into the reactor building basement concrete or potentially through the ground below.
The plan doesn’t clarify how much human entry to the underground base unit would be allowed or required. Seeing broader planning for potential scenarios would seem a wise move after early work found unexpected surprises causing designers to go back and rework plans. For such a plan to be under development means there is some thought among the decommissioning research teams that a worst case scenario could exist. These would include further inspections inside the containment structures and horizontal drilling below the reactor buildings to obtain soil samples.
The divergence between the work of the parties that have to actually plan the decommissioning work vs. the parties that have a stake in comforting public relations is quite clear. The very notion of such a plan raises questions about the true nature of the meltdowns.
A complex system of drilling equipment, debris retrieval, and nuclear waste casks would be included in the system. Additional inspection work will be required to determine if this new method will be needed.
The same report also includes the controversial sarcophagus plan.