The coolant's radioactivity has been reported as 16,000 becquerels per liter in the roughly liter-and-a-half (0.39-gallon) spill. 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 information, of course, can only be as good as the reporting-and the scale itself. nuclear operators promptly notify it of any incidents. Each country has its own internal reporting requirements the NRC requires that all licensed U.S. Notes Rejane Spiegelberg Planer, who is in charge of incident reporting at the IAEA: "There is no obligation to report." So far, 63 countries have agreed to voluntarily report and rank incidents on the scale. "Certainly, in my view, this was something we should have reported initially," Jaczko says. The INES scale notwithstanding, word of this near-fission event did not reach the public until this year due to secrecy provisions put in place by the Bush administration to stop would-be terrorists and others from getting information about nuclear power plants. Subsequently, the plant was closed for seven months and a major reorganization has been undertaken by Nuclear Fuel Services, according to notes from a meeting with NRC commissioners. "That would have been the kind of event that would have been a potential." Because such fission was avoided, the incident was reported to the International Atomic Energy Agency (IAEA) by the NRC as a level 2 event on the INES scale. "Nothing did happen in terms of a criticality event," says NRC commissioner Gregory Jaczko. More than eight gallons (31 liters) of highly enriched, weapons-grade uranyl nitrate, the liquid form of transportable uranium, nearly pooled in a sufficient quantity to achieve the conditions necessary for a spontaneous chain reaction-uncontrolled fission, otherwise known as a criticality. "Two reactor events and eight nonreactor events."Īmong the eight nonreactor events was a spill at the Nuclear Fuel Services, Inc., fuel production plant in Erwin, Tenn., in March 2006. nuclear plants last year that merited ratings of 2-"significant spread of contamination / overexposure of a worker" and "incidents with significant failures in safety provisions," as the INES handbook puts it-or above, Jones says. In the case of the 1979 accident at the Three Mile Island nuclear plant near Middletown, Pa., radioactivity spread but was limited to a 10-mile radius, which led to it being downgraded it to level 5, even though it had the makings of a full-scale catastrophe due to human error. In the case of Chernobyl, all such preventive measures failed. Can you still drive the car? Yes, but you've lost one of your defenses. "It's like if you had a car accident and you broke your turn signal. Nuclear Regulatory Commission's (NRC) senior technical advisor for nuclear security. "How did the safety provisions function and how close the event was to causing a problem," says Cynthia Jones, the U.S. The latter concept refers to the numerous safeguards designed to limit the impact of potentially deadly accidents. Therefore, it fulfilled all three of the scale's criteria: on-site impact, off-site impact and so-called "defense in depth." The explosion in the reactor core spread both short- and long-lived radioactive material as far as the U.K.
Only one event, the 1986 meltdown of the Chernobyl nuclear plant in Ukraine, has merited its most serious degree, level 7.
No major nuclear accidents have occurred since it was implemented in 1992, but it has been used to assess damage from previous events. The scale ranges from level 0 (a "deviation" of "no safety significance") to level 7 (a "major accident"). alone over the next few decades, the International Nuclear Event Scale (INES) may become more familiar. But with plans to build many more nuclear reactors worldwide, including as many as 30 in the U.S. Scales are also essential to any weather report-from hurricane intensity (measured on the Saffir-Simpson hurricane scale from categories 1 to 5) to the temperature.Īn analogous scale exists for portraying the broad range of potential danger from a nuclear accident-whether it be a small leak of radioactive material or the meltdown of a reactor-though it lingers in relative obscurity. Without the measurement of magnitude 6.8, for instance, few could grasp the relative severity of the recent earthquake off the western coast of Japan. Earthquake stories are incomplete without information from the Richter scale.
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