I’ve been listening to coverage of the unfolding disaster at the Japanese nuclear reaction at Fukushima, and I can’t help but wonder about the two side notes I keep hearing.

It goes something like this: They have determined the Japanese reactor situation rates a No. 7 on the International Nuclear Event Scale, which is the worst ranking in the scale.

Then there are the caveats:

1) The emergency at Chernobyl was also a No. 7, and

2) The Fukushima emergency isn’t as bad as Chernobyl.

So, A equals B, and B equals C, but A doesn’t necessarily equal C. It would seem the No. 7 slot has some leeway built in.

For those keeping track, Three Miles Island came in at a No. 5 on the scale, which looks like a glowing food pyramid. The No. 6 slot appears to be open. How about parking Fukushima there?

If we are trying to convey that Fukushima was worse than Three Mile Island and not as bad as Chernobyl, No. 6 would seem to do it.

But the other thing that jumps out at me is the big question that no one is asking — why a scale of 1 to 7?

You could whittle down the numbers to fit in with other disaster scales rated between 1 and 5, like tornadoes (F1-5).

Or you could go the other way, the classic 1 to 10 scale.

“Why don’t you just make 7 worse?”

“No, you don’t understand. This goes to 10.”

Besides, ranking Chernobyl as the worst case scenario really underestimates the human potential. Can you imagine the coverage of the next disaster?

“Yesterday’s radiation release rated a 7, which is what Chernobyl rated. But this was so much worse than Chernobyl.”