TEPCO was going to start removing the fuel rods from the less-damaged reactor building Numnber 4 over the next few days. Today, it was announced that damage to the fuel rod assemblies, some or most of which predated the tsunami and earthquake, this could not be done. There is now uncertainty as to what is going to happen.
Here is a video by Fairewinds about this operation, which I believe was made before TEPCO decided to not continue with the removal at this time:
As you can see, there are several possible problems. Most of these problems are not related to the reasons TEPCO has given to halt the operation at this time; they are additional .