There is a big hole in the bottom of the RPV. They estimate only up to 50 % of the fuel remains in the RPV. The rest is boring into the concrete below if we are still lucky. We do not even know if the measured fission products were from the mass boring into the concrete or the mass still up in the RPV. The temperature sensor is up in the RPV. The position of the temperature sensor does happen to be near the side where they tried to look at the outside of the RPV. Some speculate that part of the melted mass could have slumped toward that wall of the RPV and might still be there or melted through the side in addition to the main mass melting out the bottom. All unknowns at this point in time.
Fukushima got a little shaker today. 4.2 on the Japanese scale. Caused some shaking at the plant. JNN camera has been done with an error since about then.
Do you have pictures of that? Is it fact or speculation? The data I have seen indicates that the most likely exit points from the PV are the instrument tube penetrations, which are not terribly large in size, but there are a fair number of them. The heat load calculation that was done at both NRC and INL indicates that if the entire core mass ended up in the containment sump the concrete degradation would be on the order of a few inches out of the six feet of thickness of the containment structure. There is additional concrete below the containment in the form of the basemat and concrete embedment. Based on the drawings I have from GE, this added thickness seems to be about 18 feet. It forms the foundation of the entire building, so it is quite a thick slab. These are calculations, not actual measurements since no one has been in there.
Aftershocks in a region that experienced a major seismic event are not uncommon. What was the result of that 4.2 other than the camera failure? I have seen nothing on the NEI or IAEA news feeds. If its limited to a camera failure, I won't worry too much about it.