NHK reports that the decommissioning authority in charge of dealing with the aftermath of the Fukushima disaster is now considering a sarcophagus to entomb the failed reactors rather than attempting to remove the melted fuel, debris and buildings.
The authority told NHK they would still consider the two fuel removal techniques but they are adding the sarcophagus option to the list. They did not elaborate about why it is now being officially added to the considered options for the plant.
The idea of leaving the plant as is and creating a sarcophagus around the three melted down reactors is extremely problematic. The groundwater issue is just one problem that would be a permanent problem. Even the ice wall if it eventually works as planned can only operate for a few years. Erosion and groundwater flows would create a permanent problem for the ocean and the region around the plant. This would also leave the fuel and crumbling buildings in place. Building failures, radioactive dust and fuel debris would all still be in place. This would need to be managed not just due to aging but further natural disasters such as typhoons and tsunami. Current problems include fuel fragments that have been found in unit 1′s torus room basement water. These have been a concern as groundwater flows through these basements that if improperly managed, more of these fuel fragments could leave the basement into the groundwater.
At Chernobyl, the new cover building there is expected to be needed for 100 years while they attempt to eventually deal with the damaged building. When and how that happens is still vague decades later.