Hiroaki Koide: "The Trouble with Nuclear Power"

Prof. Hiroaki Koide, Kyoto University Research Reactor Institute (retired), Apr 24, 2015, starting at 31:00 in (emphasis added):
Although what I’ve been describing is quite grave, we have an even more serious issue facing us, which is the reactor cores melted in Units 1-3. What are we going to do about that?… Tepco believes that there are lumps of melted fuel and they have this idea that they are somehow going to… pluck out all of these lumps… They’re saying that the first step they will take is to somehow plug the holes in the containment vessel… I believe this plan that has been presented is simply impossible to realize… We don’t even have the technology or ability now even to determine where the holes are, and even if we were able to determine where the holes are, how can we possibly repair them? We do not have the means to do so… I think the fundamental assumption of Tepco and the government that the melted fuel is sitting at the bottom in a nice little lump like a dumpling shape, I think that is impossible. It’s an impossible proposition.
What I’m trying to say is that although this picture [from Tepco] looks like a neat little situation where all of the spent fuel is put nicely into 2 little lumps, I think in reality that when one considers all of the explosions and shaking and damage that occurred, I cannot imagine that every bit of that melted fuel will be sitting nicely in one little lump, but rather it will have spread all over the place. And it’s also possible that not only would they spread horizontally, it could be that some of the fuel could actually have gone through the floor of the containment vessel as well. What I’ve just described is very, very logical for anyone who understands nuclear engineering or nuclear energy — and in recent months it has come to the understanding of the general public. In fact, this is a copy of a local Fukushima newspaper which printed an article about what I just described, instead of the government and Tepco’s description of the fuel being in one nice dumpling shape, it shows that probably they’re spread all over the place… In fact, this is the result of some announcements by even government sactioned experts… There’s no way that they will be able to get all of it. I believe that fundamentally the idea to somehow remove the melted fuel… is simply impossible to realize.
The only possible way we can eventually deal with this accident is to do what was done at Chernobyl. Which is to create a concrete coffin or sarcophagus for the facility.  Like the spent fuel pool at Unit 4… Units 1-3 have pools that are filled with spent fuels and they must be removed, otherwise we cannot even think about building a concrete coffin… How long will it take for the spent fuel rods to be removed to a slightly less dangerous place? We have no idea. I thnk Tepco and the Japanese government do not know how long this procedure will take… How many years from now will that [sarcophagus] be done? I cannot even begin to make a prediction, in fact I probably will not be alive when the project starts… Although the Chernobyl accident was a  terrible accident, it only involved one reactor. With Fukushima, we have the minimum [of] 3 reactors that are emitting dangerous radiation. The work involved to deal with this accident will take tens of years, hundreds of years.
Watch the press conference here
https://www.youtube.com/watch?feature=player_detailpage&v=nCbXX3DURd0#t=1860