From an AP piece:
Radioactive debris from melted fuel rods may have seeped deeper into the floor of a Japan’s tsunami-hit nuclear reactor than previously thought, to within a foot from breaching the crucial steel barrier, a new simulation showed Wednesday.
Emphasis mine. Note that they don’t actually know where the fuel has actually gone:
Some experts have raised questions about achieving the “cold shutdown,” which means bringing the temperature of the pressure vessel containing healthy fuel rods to way below the benchmark 100 Celsius (212 Fahrenheit). They say the fuel is no longer there and measuring the temperature of empty cores is meaningless, while nobody knows where and how hot the melted fuel really is.
Which all probably means that the reactor vessel is cooling down nicely due to the absence of any fuel. 30cm of concrete doesn’t fill me with great confidence. Didn’t the Russians end up mining under Chernobyl and pouring a new concrete slab?
It’s hard not to get the impression that Tepco is still winging it, and that this saga is a long way from over.