gbrumfiel writes "A new study posted for open peer-review suggests that the nuclear reactors at Fukushima Daiichi released far more radiation than the Japanese government initially estimated. The study [PDF] uses global radioisotope and meteorological data to calculate the size of the release from the plant. Nature News reports that, contrary to official claims, the model shows that fuel being stored in a pool at unit 4 released a significant amount of cesium-137, a long-lived contaminant that has spread across the countryside. It also says that some Xenon-133 may have been released early on in the accident, suggesting that the plant was already damaged before it was hit by a tsunami. Overall, it estimates that Fukushima released about twice as much cesium-137 as the government claims and half as much as Chernobyl."