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livello elementare
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ARGOMENTO: EMERGENZE AMBIENTALI
PERIODO: XXI SECOLO
AREA: GIAPPONE
parole chiave: incidente nucleare
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Fukushima, what happened
images and text from source: http://fukushimaontheglobe.com/
The Nuclear Accident
The “Great East” Earthquake occurred at 2:46pm on March 11th recorded magnitude 9.0, has given tremendous damage to the northern part of Japan, especially in the prefectures of Fukushima, Miyagi and Iwate. The earthquake and tsunami triggered the worst nuclear accident since Chernobyl. The Fukushima Daiichi nuclear power station located in the Pacific Ocean coast received huge damage by the earthquake and tsunami. The piping facility in the building, the facilities for the external power supply and backup power were destroyed. The next day, 12th in the early morning, the leakage of radioactive materials had been found in front of the main gate of the nuclear power plant. The steam was filled in the building by the core melt down caused by the dysfunction of the cooling system. Lots of radioactive materials were scattered in the environment thorough “vent” to reduce the internal pressure and the hydroponic explosions of the nuclear reactors. According to the estimates by Asahi newspaper based on the data from TEPCO, the amount of radioactive materials released into the air were 770,000 tera Bq until beginning of Apr.11,2011, and still going on with high risk. It is said that this amount is about 20% of the Chernobyl accident. On April 12th, 2011, Nuclear and Industrial Safety Agency raised the rate of the accident from level 5 to the level 7, the same level as Chernobyl.
Areas
In this page, transition of evacuation orders and restricted areas are explained in chronological order. To know the current status of the area, please click here.
Evacuation orders
On Mar.11, 2011, immediately after the accident, the government ordered residents in only 3km radius around the Fukushima Daiichi Nuclear Power plant to evacuate. As the seriousness of the accident became apparent, the areas of evacuation order were gradually expanded. On March 12, 2011, after the 1st explosion at the nuclear reactor No.1, the government expanded the areas of evacuation within 20km radius from Nuclear Power Plant. On March 15, after an explosion was heard at the reactor No.2 & No.4, the government instructed the residents, living between 20km-30km radius from the NPP, to stay inside house. As the result of System for Prediction of Environmental Emergency Dose Information (SPPEDI) was still not reflected at this point, many people did not know that the wind and the rain on March 15th brought radioactive particles to spread northwest direction from the NPP.
Restricted areas
On April 22, 2011, the government designated the 20km radius around the NPP as a restricted area and prohibited entry into the area excluding those engaged in emergency response.
At the same time, the government designated two more different areas, “deliberate evacuation areas” and “evacuation prepared areas in case of emergency”.
Deliberate evacuation area and Specific Spots Recommended for Evacuation
“Deliberate evacuation areas” were designated as the area excluding restricted area where the annual cumulative dose of radiation was expected to reach 20mSv/year after the accident. Residents lived in this areas required to evacuate within about a month to reduce the risk of being exposed to radioactive materials, though the instruction was too late. In addition, ‘Specific Spots Recommended for Evacuation（SSRE)’ was set on June 16, 2011 referring to the areas which contain high radioactive contamination, including numerous hot spots. The defined level of radiation in the SSRE suggests the cumulative dose equivalent to 20mSv/y or higher.
Evacuation prepared areas in case of emergency
“Evacuation prepared areas in case of emergency” was designated as the areas excluding deliberate evacuation areas, among the areas of in-house evacuation on April 22, 2011. The residents are required to remain prepared to move out of the areas or in-house evacuation in case of emergency regarding the NPP. On September 30, 2011, the areas were lifted.
Rearranging the restricted areas and areas to which evacuation orders have been issued
The government decided to rearrange the restricted areas and areas to which evacuation orders have been issued after “the safety of the NPS was ensured” by completion of Step 2 on December 26, 2011. According to their plan, the restricted areas will be lifted after considering the period for preparing tasks such as confirmation of infrastructure and security. The areas to which evacuation orders have been issued will be rearranged into 3 areas responding to the annual cumulative dose
3 areas to be arranged
The government decided to rearrange the areas to which evacuation orders have been issued into 3 areas as follows. Practical operations for designating areas to which evacuation orders have been issued as newly designated areas By Ministry of Economy, Trade and Industry.
Current status of the areas
Source: Ministry of Economy, Trade and Industry （As of Feb 13th,2014）
– See more at: http://fukushimaontheglobe.com/the-earthquake-and-the-nuclear-accident/evacuation-orders-and-restricted-areas#current
– See more at: http://fukushimaontheglobe.com/the-earthquake-and-the-nuclear-accident/whats-happened#sthash.eE9c8GCL.dpuf
Decontamination from http://reportage.corriere.it
To decontaminate the field, Tsuboi has followed the guidelines of the Japanese government, which – depending on the type of surface and the concentration of radioactive materials – involving the removal of contaminated soil, the reversal of the soil or the water washing with high pressure jet. According to the Japan Atomic Energy Agency, these techniques would reduce the radiation by almost 70%, but some experts remain critical about the choice of areas to be decontaminated. Already in 2012, an international group of scientists did this to the Japanese authorities that the selective decontamination could not solve the problem of so-called hotspots – or places where the radiation is particularly high. These include Wolfgang Raskob, director of the Institute for nuclear technologies and energy of Karlsruhe, argues that “to be effective, the decontamination should cover all the areas where people live.” “The total decontamination“, however, “it is impossible.” While Miyakoji was the first district in the exclusion zone was declared to be decontaminated, the government is planning to complete the decontamination of all areas at risk by 2021.
So what’s now? Stay with us …
preview image: Protestation anti-nucléaire at Tokyo le 9 March 2014 – photo credit TORU YAMANAKA / AFP BLOG. Fukushima : attention aux possibles irradiations (28) – Sciences et Avenir
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