The Fukushima disaster is already as bad as Chernobyl according to the International Atomic Energy Association's scale
That is quite a logical leap based solely on the INES rating. Fukushima is in the same category as Chernobyl, but this is also the highest category there is, and Chernobyl was past the boundary by a huge margin.
For example, the criteria for the total release of iodine-131 in a level 7 accident is "tens of thousands of TBq". Chernobyl released 1.8 million TBq. Fukushima has released about 370,000 TBq so far.
Chernobyl had killed 31 people by this point while Fukushima has had negligible health effects so far due to much better emergency response. The INES rating does not account for this, only for the amount of material released.
20%? That's a lot closer to Chernobyl, radiation-wise, than I expected. Why haven't the effects been anywhere near as bad, given that the released radioactivities are of the same order of magnitude?
You can get this from wikipedia, but the short answer is that the graphite moderator Chernobyl used ignited. The burning graphite released smoke fallout, which spread very far due to wind. Fukushima released about an order of magnitude less nastiness, and it hasn't spread as far in quantity (though some of it is in the ocean).
The Chernobyl reactor blew wide open, sent core bits flying, then burned for a couple of weeks. Fukushima remains mostly contained. I think release has been mostly through water. But it's not over yet and we don't know what the total effects will be.
That is quite a logical leap based solely on the INES rating. Fukushima is in the same category as Chernobyl, but this is also the highest category there is, and Chernobyl was past the boundary by a huge margin.
For example, the criteria for the total release of iodine-131 in a level 7 accident is "tens of thousands of TBq". Chernobyl released 1.8 million TBq. Fukushima has released about 370,000 TBq so far.
Chernobyl had killed 31 people by this point while Fukushima has had negligible health effects so far due to much better emergency response. The INES rating does not account for this, only for the amount of material released.