tsutsuji said:
Pages 23 & 24 are the results of simulations based on the assumptions written on page 20. Page 20 says "It was assumed that the fuel debris had accumulated at the two (equipment/floor) drain sumps in the pedestal." It is logical that the simulation results are consistent with the assumption, but the question remains whether the assumption is correct in the first place.
Well yes but there are other assumptions at work here, any number of which could be wrong.
For example I don't know if it is possible that fuel could go in the sump pits but not go on to contaminate the RCW system like seems to have happened in reactor 1.
And there are many assumption made in earlier simulations which could affect later simulations, as I mentioned earlier when complaining about the timing of certain events shown on the TEPCO graph. This evening I have done my further research on this, at least in relation to reactor 2.
To be clear, I am looking at the earlier studies of how much of the core melted, because the results of these will affect the later analysis about core deposition within the drywell and core-concrete reactions, etc.
Firstly I throw away TEPCO case 1 as usual, because it was far too optimistic, estimates from the model failed to match recorded data, and it concluded that no RPV damage had occurred.
TEPCO case 2 is a better fit. This one matches the measured pressure etc data much better, and its conclusions are more realistic in terms of RPV damage. But when the government cross-checked this case, by running the model simulation themselves, they had differences in timing of RPV failure. This is what I was complaining about on the graph used in TEPCO's later analysis, they still had the graph showing RPV damage failure 109 hours after the earthquake, which is not till the 16th March. Government analysis put the failure much earlier, at 22:50 on the 14th, which seems like a better fit with events and measured data.
So, I am concerned if TEPCO have fed a different time for some core falling into containment than seems reasonable.
Then there is the question of how successful the water pumping into reactor 2 was during the first hours of attempting this stuff. And here too I see some possible contradictions between different analysis. I will do a bit more research and checking before commenting on this in detail.
