The information, of course, can only be as good as the reporting—and the scale itself. The leaks of nuclear fuel rod cooling water, a burning transformer and other problems at the world's largest nuclear reactor—Kashiwazaki-Kariwa in Japan—caused by the earthquake this past week have yet to rise above INES level 0. The coolant's radioactivity has been reported as 16,000 becquerels per liter in the roughly liter-and-a-half (0.39-gallon) spill. (One becquerel is the measure of a material's radioactive decay equal to one nucleus disintegration per second.) To merit a 2 on the scale, for example, would require the leak of material emitting several gigabecquerels. "We can't even measure that [Japanese spill] with any kind of device that we have," Jones says.
A malfunction in the water pump at the Oyster Creek nuclear power plant in New Jersey caused it to shut down on July 17 and release one curie of tritium (an isotope of hydrogen) in vented steam, according to the NRC. One curie equals 37 billion becquerels, "just half the radiological exposure of living with a household smoke detector," according to Exelon, the power company that runs the plant. As a result, this incident at the oldest operating nuclear reactor in the U.S. also does not merit inclusion on INES.
But with more nuclear power plants being built and planned (there are licenses pending at the NRC to build 30 plants in the U.S.), the aging of those currently on line as well as the proliferation of radioactive materials used in other applications, the INES scale may yet become more familiar. "I like to compare it with a very simple scale that is a thermometer," IAEA's Spiegelberg Planer says. Level 0 is equivalent to the human body at its normal temperature. Level 2 might be a slight rise in temperature that prompts taking an aspirin. "You don't go to the emergency room if you can take an aspirin," she says, whereas at level 7 "you are already in the hospital."