By Jutta Wolf CourtesyIDN-InDepth NewsReport
BERLIN (IDN) - The findings of a new study by an international team of researchers who probed into the Fukushima nuclear disaster suggest that earthquake prone areas should be treated as 'atomic power plant free zones'.
Scientists from Norway, Austria, Spain and the United States have found "strong evidence" that the Great East Japan earthquake of the unprecedented magnitude of 9 caused "structural damage" to the Fukushima Daiichi nuclear power plant, emitting radioactive Xenon gas, before the tsunami tidal wave brought a train of havoc.
The investigation also revealed that radioactive emissions from the power plant in the aftermath of the earthquake lasted longer than presumed and are therefore higher than most studies conducted before estimated..
Dr. Andreas Stohl from the Norwegian Institute for Air Research (NILU), lead author of the study published on October 21 said: "Our calculations are based on about 1000 measurements of activity concentrations and deposition conducted in Japan, USA and Europe. This is the most comprehensive investigation so far. There is no doubt that the Fukushima accident is, at least in terms of the isotopes Xenon 133 and Caesium 137, the most significant event after the catastrophe in Chernobyl 25 years ago."
Investigations indicate an emission of 16700 Peta-Becquerel (1 Becquerel is one radioactive decay per second, 1 Peta-Becquerel equals 1015 Bq). This is the largest noble gas release in history not related to nuclear bomb testing, exceeding the Chernobyl noble gas emission by a factor of 2.5.
The Becquerel is named after Henri Becquerel, who shared a Nobel Prize with Pierre and Marie Curie in 1903 for their work in discovering radioactivity.
The start of the radioactive emissions was on March 11 at about 3 pm (Japanese time) and therefore before the tsunami hit the coast. This leads the scientists to believe that the earthquake at 2.46 pm may have led to "structural damage" of the reactor.
"The results of this study are further evidence refuting claims by the nuclear industry, the Japanese government and the German Reactor Safety Commission that the earthquake itself was not the reason for the disaster, but only in combination with the tsunami," said Henrik Paulitz, nuclear expert at the German affiliate of the Nobel laureate IPPNW (International Physicians for the Prevention of Nuclear War).
"The attempt by the nuclear lobby to play down the massive risk for reactors posed by earthquakes has obviously failed due to the publication of this new study. It is quite astounding to see how the Reactor Safety Commission and other German government bodies insist on clinging to this barely credible tsunami theory – probably to try to avoid reactors situated in earthquake regions, such as Philippsburg-2 and Neckarwestheim-2 (in Germany), from coming under political attack," Paulitz said.
The emissions of aerosol‐bound nuclide Caesium137 – known to be particularly dangerous for human health – in the months of March and April were just under 36 PBq, according to the authors. Although only nearly 2% of the total Caesium 137 inventory contained in the Fukushima Units 1 to 3 and the spent fuel pond at Unit 4, the amount released in the period of time studied amounts already to about 40% of the estimated release from the Chernobyl reactor, according to the study.
Due to weather conditions (prevailing west wind, low precipitation) about 20% of the released Caesium 137 fell on the Japanese mainland, the remaining 80% over the Pacific Ocean.
The massive release of Caesium that occurred early on March 12 during the first hydrogen explosion in Unit 1 has been underestimated until now, according to the authors. Exactly during and following the highest rates of Caesium emissions on March 14 and 15, large areas in the East of Honshu Island were affected. Unexpectedly high levels of Caesium 137 were emitted on March 16 and 19, which were apparently reduced by the recommencement of cooling of the spent fuel pond at Unit 4.
Dr. Gerhard Wotawa of the Central Institute for Meteorology and Geodynamics (ZAMG), said: "ZAMG was the first institute worldwide that published, as early as ten days after the accident, an estimate of high emissions of radioactive substances from Fukushima‐Daiichi. This analysis was based on a few data available to us at this time, and is now fully confirmed by a comprehensive analysis."
Fortunately, said Paulitz, the metropolitan area of Tokyo with its 36 million inhabitants escaped the worst because there was no rain at the time when the densest part of the radioactive plume passed over the capital on March 15.
On the other hand, radioactive fallout affected large areas of the Japanese mainland between March 20 and 22 from the region north of the Fukushima nuclear plant to Osaka in the south. Heavy rain that followed nearly completely cleansed the atmosphere of Caesium 137. However, large areas of Japan, including Tokyo received a considerable amount of exposure to Caesium.
Former Prime Minister Naoto Kan recently made clear how dramatic this period of time really was in revealing that his government had considered evacuating Tokyo. This would have meant that Tokyo would have become an exclusion zone. In that case, Kan said that he doubted that Japan could have continued to function as a state.
The study was conducted by a team of researchers from the Norwegian Institute for Air Research (NILU) in Kjeller, Norway, the Institute for Meteorology of the University of Natural Resources and Life Sciences (BOKU-Met) in Vienna, the Austrian Central Institute for Meteorology and Geodynamics (ZAMG) in Vienna, the Institute of Energy Technologies from the Technical University of Catalonia in Barcelona (INTE), Spain, and by the Universities Space Research Association, Columbia, MD, USA. [IDN-InDepthNews - October 27, 2011]
Picture: Satellite image on 16 March of the four damaged reactor buildings
Credit: Wikimedia Commons
