TEPCO has released a video that shows work being done at the Fukushima plant. Very interesting to watch.
One gets a real sense for the devastation the tsunami inflicted while watching that clip.
TEPCO also recently released this PDF file that gives an overview of work being done. I will add some pictures from it:
In the above picture one can see how they plan to rig up the new heat exchangers for reactor 1. Within the reactor building, but outside the containment, they will put a water to water heat exchanger. They will pump water from within the containment through this heat exchanger, where it transfers the heat to a secondary circuit that in turn flows to a heat exchanger outside of the reactor building that dumps the heat to the air. This is the original plan TEPCO had before they realized the full extend of the damage to the number 1 core and containment, so it is not sure they will progress as described. But the secondary heat exchanger and its piping is already being built.
Tepco also shows the above picture on how they plan to reuse leaking water from the containment as cooling for the reactor. It is not clear how the two plans are connected to each other. I would assume the second plan is the one that is going to be used instead of the first plan. Instead of taking water directly out of the containment they will use the existing leakage paths, purify the water and pump it back into the reactor.
For the number 2 reactor shown above the main problem is to stop the leakage from the suppression pool. They plan to excavate the reactor building in order to access the room where the suppression pool is housed and then fill the entire volume with grout. Considering that (probably) the suppression pool is leaking at number one as well then maby this plan will be implemented there as well (just my speculation).
Both in unit 2 and 3 are they planning to reuse the leaking water in the same manner as in unit 1.
In the rest of the document they give some basic information on how they plan to clean the massive amounts of contaminated water that exists on the site, some details on the protective building they want to build around the reactors and how to prevent more contamination of soil, water etc. Well worth scrolling through, massive work is certainly ongoing at the site and it seems TEPCO has a solid plan that they are implementing. Of course more surprises will without a doubt pop up during work, but it looks promising. We are still waiting for more in depth information on the situation of the number 2 and 3 reactors.
New York Times Venting Failure in the Nuclear Reactors at Fukushima Daiichi
Reuters UK nuclear power gets green light