Now, at least one CTBTO member state, Austria, intends to make some of the data public in the form of summary reports and forecasts of global radiation spread.
Nature has also learned that initial CTBTO data suggest that a large meltdown at the Fukushima power plant has not yet occurred, although that assessment may change as more data flow in during the coming days. Lars-Erik De Geer, research director of the Swedish Defence Research Ins ute in Stockholm, which has access to the CTBTO data and uses it to provide the foreign ministry and other Swedish government departments with analyses, says that the data show high amounts of volatile radioactive isotopes, such as iodine and caesium, as well the noble gas xenon. But so far, the data show no high levels of the less volatile elements such as zirconium and barium that would signal that a large meltdown had taken place -- elements that were released during the 1986 reactor explosion in Chernobyl in the Ukraine.
Rather, the data sit well, he says, with a scenario wherein the main release of radioactivity has come from the release of excess pressure in the containment vessels of affected reactors, and the subsequent explosion of the evacuated hydrogen-laden steam within the reactor buildings. The radioactive plume will spread around the hemisphere within weeks, he predicts, but the levels of radioactivity outside Japan will not be dangerous. The levels in Japan itself, outside the immediate vicinity of the Fukushima power plant, "wouldn't scare me", he adds.