About unit 4 explosion breaking gate theory ...
This theory is interesting, but it relies on the assumption that the pool was quite empty at the time of the explosion, in order to explain that in the days after there were no signs of a dry pool, like for instance zirconium fire. I've even seen drawings with uncovered fuel assemblies at the time of the explosion.
Now looking at SFP4 losses rates, there are still missing pieces to me to explain such a point of departure.
Explosion happened Mar. 15th around 6 AM. If fuel assemblies were uncovered at this time, this means that all water above it would have boiled, leaked or splashed before the explosion. According to my calculation, this is about 870 tons of water. Without considering splashing, this means 217 tons losses per day. Losses of water due to splashing in SFP in other units (5 & 6) would help know the impact of it. Splashing may be one missing piece. Any information anyone?
Then: they put 1554 tons of water afterwards in order to reach the "pool is full" signal, which was first reached on Apr. 13 14:55. This is an average 46 tons per day loss. There are a few injections / spray for which we lack volumes (two helicopter drops, and one injection between Mar. 26 06:05 and Mar. 26 10:20). Even considering a big injection for the missing one (180 tons), and 2 drops of 20 tons each, one gets an average loss rate of 52 tons. Even splitting calculations between period with or without skimmer surge tank levels, you got roughly a rate about 50 - 60 tons per day loss.
So the situation would have been the following:
- prior to explosion, they suppose SFP4 had an average 217 tons per day loss
- after it, data only gives 50 to 60 tons per day.
Well, not only explosion saved SFP4 from a zirconium fire, and fuel melt, but it also stopped leaks apparently! How can you explain that? Rubbles filling the pool? But the pool is full of casks, and it may be very difficult for rubbles to go the places where there are leaks.
Moreover last video did not show that much rubble in the pool (attach1). Which seems weird also, as in another picture (attach2) shows SFP4 surrounded by a LOT of rubbles.
Next, looking at a
http://www.youtube.com/watch?v=AUx7lIUsogA&NR=1", there is a view that is I think of the reactor wel (see circle in attach3). No steam above it, while lot of steam left of it (red / green circles in attach4), above SFP. We would expect at least some steam above reactor wel is gate would be broken, wouldn't we?
The gate broken theory is interesting, but it seems to contradict with other observations.
Pictures of unit 4 before and after explosion clearly qualify an hydrogen explosion. The key to me would be to estimate the amount of hydrogen with different water level drop rates, and see with this volume if one can explain the damages in unit 4. I've heard here and there that there were models to calculate hydrogen release from zirconium-steam reaction, maybe it would help qualify one or the other assumption. Maybe still covered assemblies, but surrounded by boiling water, can produce enough hydrogen to explain damages to unit 4? I don't know. I've seen a post on this question, quite interested in it.
Additionnally, we can also quantify the volume of water brought through the broken gate. It has to be significant in order to "save SFP4".
Well if the gate broke during the explosion it brought water that was above the reactor wel in the SFP. My own estimate of this volume is 1200 m^3, using this input:
- Top of RPV is at 31660
- Service floor is at 38900
- This is 7.24 meters height
- Assuming width identical to SFP, 12.2 meters
- Third length is 2 times distance between 2 pillars: 2 x 6.76 = 13.52 meters
- Estimated volume: 1200 m^3
Any remark anybody on this volume estimate?
NB: Some part of this providential water may have turned into steam due to the heat of the explosion, reducing its benefits...
