Yesterday I read an intriguing article that showed how the IAEA (International Atomic Energy Agency) placed nuclear disasters on a seven point scale . The scale is a logarithmic one where each increasing number is ten times as much of a threat or worry as the number immediately below (not unlike the Richter scale for earthquakes actually). Since there haven’t been a large number of nuclear disasters so far in the brief history of atomic energy, there are not many disasters to choose from. Let us look at the historical contenders for the upper ranks and consider what the current Japanese disaster  would have to do to compete for the upper spots.
7 Points (out of seven): Chernobyl
The current heavyweight champion of the world of nuclear disasters is Chernobyl, whose effects on the Ukraine and Belarus have been nothing sort of horrendous. If you want to see or read about how bad it is in a brief way, there is a good place to go here . The Chernobyl disaster killed a lot of people from radiation poisoning, created a ghost town, harmed groundwater supplies and made farming impossible in a large amount of Belarus, the Ukraine (and other parts of the Soviet Union) and spread nuclear contamination to many countries. Its effects, and the increased rates of cancer in many countries, have been immense. There is still, some 25 years after the disaster, a 30km exclusion zone around the former site where people cannot visit without government permission (and protective gear).
6 Points (out of seven): Three Mile Island
What makes 3 Mile Island a 6 on the scale is the fact that the reactor core started to melt in that 1979 disaster. To melt a reactor core means that temperatures must be over 1000 degrees–it takes a temperature of about 2000 degrees to reach full (Chernobyl-style) meltdown. According to estimates, about half of the metal surrounding the uranium pellets or rods melted before water was able to cool down the reactors at 3 Mile Island. For that close call, the Pennsylvania disaster rated the second-highest score on the nuclear disaster test. No other disasters since Chernobyl have reached the highest level until now.
Where the Fukushima disaster ranks:
As of last night, with the explosion of hydrogen gas in the plant and the attempt to cool down rods using seawater (basically conceding that the plant was useless and would no longer be used to generate power), and the apparently lowering amounts of radiation, the Fukushima disaster rated a 5 on the scale. It was already solidly in third place as far as the history of nuclear power disasters is concerned. Unfortunately, that is not the end of the story.
Right now, unfortunately, Japanese officials concede that the nuclear rods in all three of the plants at Fukushima appear to be melting . Melting metal automatically moves this disaster into the range of a 6. What we are seeing already ties 3 Mile Island for the second-worst nuclear power disaster of all time. If by some means the rods are cooled before a full meltdown occurs (and let us not forget that the concrete containment wall around one of the three melting plants has already exploded), we could be eyewitnesses of the worst nuclear disaster since Chernobyl, one that is likely to have considerable effects on the environment of Japan, on the long-term health of the Japanese people and those of other areas where the radioactive plume travels, and even on the international relations of Japan and the potential of reparations, massive lawsuits, and indefinite expenses related to health and other claims.
We should know within the next few hours or days whether Japan’s disaster will reach the highest levels of catastrophe, but it ought to be clear that nuclear plants on earthquake faults are not a wise idea, simply because the catastrophic risk of failure and the possibility of events going beyond the modest level of human control is unacceptable with regards to nuclear processes. The interests against nuclear power in general are likely to be greatly strengthened by the current Japanese disaster, and nuclear power is likely to be seen as even more risky and dangerous in general as a result of this particular crisis. In a world that desperately needs power, that threatens to take one more option off the table.