ASN takes stock of the situation of the Fukushima Daiichi nuclear power station the radiological consequences in Japan and in Europe
I. Technical situation of the Fukushima Daiichi plant
A. Situation of the reactors
The 1, 2 and 3 reactors of the Fukushima Daiichi plant continue to be cooled by injection of fresh water directly into the tanks containing the fuels. The means for injecting water into the tanks have been made reliable. They make it possible to maintain the temperature of the primary circuit (RPV) around 40 ° C for the reactors No. 2 and 3 and 25 ° C for the reactor No. 1.
The primary circuit is nevertheless not waterproof; the water injected into it is recovered in the lower parts of the buildings (see diagram below).
Diagram of the injection of water into the vessels of the reactors. Diagram of the injection of water into the vessels of the reactors.
B. Cooling of spent fuel storage pools
The reactor pools are cooled in a closed circuit. The temperature of the water is kept below 25 ° C.
Cooling reactor pools in a closed circuit
C. Contaminated water management at the site
The water stored at the site is pumped, stored, processed and then reinjected in part in reactors No. 1, 2 and 3. By mid-December 2011, about 200 000 tons of water had been processed; 80 000 tons of treated water had been reinjected into the reactors; 135 000 tons of treated water had been stored in tanks on site.
In order to treat the effluents generated by the fuel cooling actions, the operator has commissioned water decontamination and desalination plants, provided in part by Kurion and Toshiba.
D. The limitation of radioactive releases
In order to limit the dispersion of the contamination, the recovery of reactor building No. 1 was completed on October 28 2011. A similar operation is studied for reactors 3 and 4 whose buildings are the most damaged.
Radioactive gaseous releases are continuing; they are of the order of 60 MBq / h or 10 000 000 times less than the activity rejected at the time of the accident. A flue gas treatment plant operates for No. 1 and 2 reactors.
Radioactive water leaks are regularly detected, especially at the effluent or waste treatment facilities. The construction of an enclosure to limit radioactive discharges to the sea is planned.
Debris disposal operations on the site continue (29 000 m3 was evacuated in mid-December).
II. Management of radiological consequences in Japan
1. Synthesis
The characterization and general monitoring of the environment are coordinated by the Japanese authorities and carried out by different actors. The different measures are detailed in the Comprehensive Monitoring Plan. Radioactive cesiums are now in the majority in the environment, the iodines having decreased under the effect of radioactive decay (IRSN note 27 / 09 / 2011). At sea, despite the large quantities released, the conjunction of two large marine currents near the site has resulted in a very large dispersion of radionuclides (IRSN note 26 / 10 / 11)
The assessment of worker exposure is updated by TEPCO; nearly 20 000 workers have already benefited from an internal dose assessment.
A post-accident zoning was defined by the Japanese government 22 April 2011 then updated, to ensure the protection of the populations residing in the prefecture of Fukushima. The areas most contaminated by radioactive substances are banned from access and the populations residing there have been rehoused. Beyond these territories, decontamination and enhanced surveillance actions are initiated.
Enhanced surveillance of levels of contamination of food produced in Japan has been organized at the level of the prefectures most affected by the contamination, or even beyond. The results of these analyzes are updated weekly. The balance of the controls carried out since March 2011 is as follows: among the 97 664 samples analyzed on all the 44 Japanese prefectures, 1 078 (1,1%) are higher than the maximum allowable Japanese levels.
A law regulating the decontamination of the contaminated territories was promulgated by the Japanese government 30 August 2011. The Japanese government is responsible for decontamination, with the exception of areas where the predicted exposure is less than 20 mSv / year. In these, the municipalities are responsible for the decontamination plan. This decontamination work, affecting the urban, agricultural and forestry environment is accompanied by the regular publication of technical documents, enriching themselves regularly with their own feedback. Waste management has also been the subject of specific provisions provided by the law of 31 August 2011.
The guidelines for compensation have been set by the Dispute Reconciliation Committee for Nuclear Damage Compensation. Compensation for people and professionals is under way; for this purpose a specific fund has been set up and endowed with 6 billion euros. A balance sheet of the indemnities paid by TEPCO was published in 18 December 2011.
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Suite / source: http://japon.asn.fr/index.php/Japon/Com ... -mars-2012
Full version .pdf: https://www.econologie.info/share/partag ... 8MXLfY.pdf
And IRSN file:
On February 28, 2012 in Paris, IRSN organized a press point on the theme "Fukushima, one year later", with the participation of Jacques Repussard, Director General of IRSN, Thierry Charles, Deputy Director General in charge of nuclear installations and systems, Didier Champion, director of the crisis, and Jean-René Jourdain, assistant to the director of human protection.
This file contains the video recordings and the presentations of the subjects treated during this press point: the report of the Fukushima accident (state of safety of the site, of the contamination of the grounds, health monitoring of the population), the perspectives of reconquest of the contaminated territories, scientific collaborations of the IRSN in Japan.
In this section:
* Situation of the Fukushima Daiichi nuclear facilities
* Assessment of the environmental consequences of the accident
* Simulation of the marine dispersion of liquid radioactive releases caused by the Fukushima accident
* Simulations of the atmospheric dispersion of radioactive releases
* The health consequences of the Fukushima accident
Folder: http://www.irsn.fr/FR/base_de_connaissa ... un-an.aspx
Including a video conference of 1h15: http://www.youtube.com/playlist?list=PL ... ature=plcp