Current Fukishima headlines #2:

[FBaggins]

22. Further evidence is found on page 29

They give a hypothetical example of an INES 7.

The total release of radioactive material was about 14 million TBq, which included 1.8 million TBq of 131I, 85 000 TBq of 137Cs and other caesium radioisotopes, 10 000 TBq of 90Sr and a number of other significant isotopes.

Criteria - 2.2. Activity released
Explanation- The factors for the radiological equivalence of 90Sr and 137Cs from Table 2 are 20 and 40 respectively, so the total release was radiologically equivalent to 5.4 million TBq 131I. This is rated at the highest level on the scale, Level 7 “equivalent to more than several tens of thousands of TBq 131I”. Although other isotopes would have been present, there is no need to include them in the calculation, as the isotopes listed are already equivalent to a Level 7 release.

Criteria 2.3 Doses to individuals
Explanation - Not necessary to consider, as event is already rated at Level 7.

Rating for impact on people and the environment - Level 7.

The conclusion here is clear. Once you get to a Level 7, numbers above that are irrelevant... because 7 is the top of the scale.