LabratSR said:
Another update from TEPCO and yet again, absolutely nothing covered other than the water issues. Status of the clean-up of the units? Fuel removal from Unit 4 SFP? Removal of the Unit 1 cover? Location of the cores? And on and on.
Thanks for posting.
Others have pointed out documents that give some clue as to timescales for some of these tasks, though I'd have to go back over a mess of documents to fill in some of the remaining gaps. I'll return to some in the coming hours or days but for now I will just deal with core location surveys.
Reactor 3 needs more decontamination inside the reactor building before they do any useful surveys. We hear very little about reactor 1. Reactor 2 is where there has been the most progress, including in recent months.
The last thing we learned about reactor 2 is not many pages ago on this thread, with the last survey revealing a rate of 36 Sv/h just outside the pedestal opening. But now they have to look at the results & tricky operating conditions encountered during that survey in order to plan the next survey which will hopefully go inside the pedestal area and give a better idea about core location.
One other thing I may have learned from that survey, if all the documents & diagrams were accurate, is that the location of the full 'door' into the pedestal area, is to the south-east. This is based on an assumption that this door, which was of interest to those wondering about molten core flow or splashing outside of the pedestal area, is opposite the pedestal opening that they got close to in this survey (this surveyed opening is more like a window than a door, and is used to replace control rod drivers).
Anyway, when trying to guesstimate core location at this stage, apart from that 36 Sv/h figure for reactor 2, and the various theoretical analysis done with models, I think the only other thing we have to go on is the state of the torus rooms at the three reactors. It is tempting to suggest that radiation dose levels in the torus rooms of reactors 2 & 3 are not spectacular enough to promote theories about core migrating away from the drywell containment in these reactors. But the very limited surveying possible at reactor 1 torus room, along with the levels of radiation measured there, may hint at a more interesting story for that reactors core. But I expect it would be grossly premature to make any conclusions based on this, its just what I'm throwing out there during the long wait for more substantial data. Thoughts more than welcome, including whether the 36 Sv/h reading near the pedestal opening of reactor 2 is the sort of reading we might expect if most of the core was either in the bottom of the RPV or the pedestal area of this reactor.
