Engineers are preparing to extract the first of thousands of nuclear fuel rods from one of the wrecked reactor buildings............
This is seen as an essential but risky step on the long road towards stabilising the site.
The fuel rods are currently in a precarious state in a storage pool in Unit 4.
This building was badly damaged by an explosion in March 2011 following the Great Tohoku earthquake and tsunami.
Moving the rods to safety is a high priority but has only become possible after months of repair work and planning.
One senior official told me: "It's going to be very difficult but it has to happen."
A senior official in the Ministry of Economy, Trade and Industry (METI) told me that the rod assemblies will be lifted out in batches of 22 and in casks filled with water..................
This will be done with a new crane, recently installed in the wrecked building, after the original one was destroyed.
Two critically important issues are whether the rods themselves are damaged and therefore likely to leak and whether the casks remain watertight to ensure the rods have no contact with the air.
The METI official acknowledged the risks including a possible "release of radiation" from the fuel or if the casks holding the fuel are dropped.
He said that "countermeasures" have been prepared - including back-up wires to hold the loads and mechanisms to hold the fuel in the event of a power failure.
A briefing document released by the site's owners, Tepco, spells out a series of safety systems designed to minimize the dangers.How reassuring, but here is the conundrum:removing the fuel rods is risky, but letting them stay where they are is riskier. But we also have to add the risks of having Tepco in charge of this process.