Most people now compare data between Chernobyl and Fukushima and try to extrapolate and make predictions and recommendations – but the situation has changed. Consider the facts:
1. Meltdown is on-going at Fukushima
2. Fukushima stores a large amount of nuclear fuel.
3. The meltdown affects some corium lost underground, without protective containment.
4. Corium slowly moves downward.
5. Hydrogen is being produced in large quantities in the meltdown process.
6. Water flows in the underground from rains and cooling efforts.
I am concerned that a supercritical mass might be achieved if some corium is moved around by water for instance. The fission reaction would take place in a cloud of hydrogen, possibly turning into a fusion reaction, i.e. an H-bomb. This is a remote possibility but it is time that we consider past the Chernobyl model. Instead of lifting the evacuation limit around Fukushima, I think that it is time to extend to the whole of Japan instead.
Read also on this topic Fukushima Diary blog post “High level of radiation is making hydrogen from H2O“.