[Dan Nunn]

No doubt. But no one can deny that it is currently worse than Three Mile Island (5) and not as bad as Chernobyl (7).

[bvw]

TMI a 5? More like a 4, by their own metrics. The Japanese reactor is still only a 5 on their scale. It might become a 6. But here is the one '6' according to Wikipedia entry:

Kyshtym disaster at Mayak, Soviet Union, 29 September 1957. A failed cooling system at a military nuclear waste reprocessing facility caused a steam explosion that released 70–80 tons of highly radioactive material into the environment.

IMO the Japanese reactor park disaster will end up releasing one tenth of that or less. I would guess the release so far -- of radioactive material -- is under a ton. Since the NGO claims each level is 10x worse, we are still at a 5.