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Articles avec #special japon

De Paris à Fukushima : Les secrets d'une catastrophe

21 Juin 2017,

Publié par Bioécologie

Le 11 mars 2011, en l'espace de quelques heures, le Japon fait face à une triple catastrophe : un tremblement de terre, un tsunami et un accident nucléaire.

Au large de Sendai, au nord-est de l'île de Honshu, le séisme atteint une magnitude record de 8,9 qui provoque un tsunami. Les opérateurs de la centrale nucléaire de Fukushima perdent le contrôle de quatre réacteurs.

Ce documentaire retrace le drame humain, écologique et industriel grâce au récit et aux révélations de témoins et d'acteurs de l'événement, mettant en avant l'étonnant manque de préparation des Japonais mais aussi le courage des hommes sur le terrain.

Report: The Fukushima Nuclear Accident Independent Investigation Commission

11 Mars 2017,

Publié par Bioécologie

National Diet of Japan Fukushima Nuclear Accident Independent Investigation Commission is the commission to investigate the background and cause of Fukushima Daiichi nuclear disaster.

The Fukushima nuclear accident "cannot be regarded as a natural disaster," the NAIIC panel's chairman, Tokyo University professor emeritus Kiyoshi Kurosawa, wrote in the inquiry report. "It was a profoundly man-made disaster -- that could and should have been foreseen and prevented. And its effects could have been mitigated by a more effective human response."

Read the report here

Fukushima prefecture, Japan, 2012
Fukushima prefecture, Japan, 2012Fukushima prefecture, Japan, 2012

Fukushima prefecture, Japan, 2012

Emission of spherical cesium-bearing particles from an early stage of the Fukushima nuclear accident

29 Juin 2016,

Publié par Bioécologie

Abstract

The Fukushima nuclear accident released radioactive materials into the environment over the entire Northern Hemisphere in March 2011, and the Japanese government is spending large amounts of money to clean up the contaminated residential areas and agricultural fields. However, we still do not know the exact physical and chemical properties of the radioactive materials. This study directly observed spherical Cs-bearing particles emitted during a relatively early stage (March 14–15) of the accident. In contrast to the Cs-bearing radioactive materials that are currently assumed, these particles are larger, contain Fe, Zn, and Cs, and are water insoluble. Our simulation indicates that the spherical Cs-bearing particles mainly fell onto the ground by dry deposition. The finding of the spherical Cs particles will be a key to understand the processes of the accident and to accurately evaluate the health impacts and the residence time in the environment.

(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.

(a) A Cs-bearing particle partially embedded within a carbon paste. (b) The same Cs-bearing particle as a) but measured the next day. The particle shows a spherical shape. (c) An elemental mapping (Cs) of the particle (a). (d) The EDS spectrum of the particle a) (black line). The red line shows the spectrum from the glass substrate. The Cs in the particle shows multiple peaks. (e) An elemental mapping of the other elements within the area. O, Si, Cl, Mn, Fe, and Zn are possibly coexistent with Cs within the particle.

Internal structure of cesium-bearing radioactive microparticles released from Fukushima nuclear power plant

28 Juin 2016,

Publié par Bioécologie

Abstract

Microparticles containing substantial amounts of radiocesium collected from the ground in Fukushima were investigated mainly by transmission electron microscopy (TEM) and X-ray microanalysis with scanning TEM (STEM). Particles of around 2 μm in diameter are basically silicate glass containing Fe and Zn as transition metals, Cs, Rb and K as alkali ions, and Sn as substantial elements. These elements are homogeneously distributed in the glass except Cs which has a concentration gradient, increasing from center to surface. Nano-sized crystallites such as copper- zinc- and molybdenum sulfide, and silver telluride were found inside the microparticles, which probably resulted from the segregation of the silicate and sulfide (telluride) during molten-stage. An alkali-depleted layer of ca. 0.2 μm thick exists at the outer side of the particle collected from cedar leaves 8 months after the nuclear accident, suggesting gradual leaching of radiocesium from the microparticles in the natural environment.

Read more here

(a) Element maps of NWC-1 acquired by STEM-EDS with a STEM Dark-field (DF) image at the same area, and (top) TEM Bright-field image in which the rectangle indicates the area analyzed by STEM-EDS. The thin area around the top of the particle which was not observed in Fig. 1a was formed by a further thinning process by FIB. (b) Element maps and images of CB-8 with the same framing as in (a).

(a) Element maps of NWC-1 acquired by STEM-EDS with a STEM Dark-field (DF) image at the same area, and (top) TEM Bright-field image in which the rectangle indicates the area analyzed by STEM-EDS. The thin area around the top of the particle which was not observed in Fig. 1a was formed by a further thinning process by FIB. (b) Element maps and images of CB-8 with the same framing as in (a).

Serum microRNAs are early indicators of survival after radiation-induced hematopoietic injury

14 Mai 2015,

Publié par Bioécologie

Indicating Radiation Injury. Three Mile Island, Chernobyl, and Fukushima were catastrophic nuclear power plant accidents. The radiation from these accidents not only took an immediate toll on human lives, but will also persist long-term, as individuals will suffer from cancer, gut damage, and infections. On the cover, engineers at the Fukushima Daiichi Nuclear Power Plant fix the "ice wall" to reduce radiation-contaminated water from entering clean groundwater, and thus protect people from future radiation injury. In another effort to protect human health, Acharya et al. identified microRNAs associated with hematopoietic damage and long-term survival in mice exposed to different sublethal doses of total body irradiation. Such RNA signatures may distinguish humans with mild radiation-related injury from those with more severe (often nonrecoverable) bone marrow damage. Studies with human samples will allow for validation of such indicators, as well as investigation into new intervention measures, to improve patient care and to enhance survival after radiation exposure. [CREDIT: K. MAYAMA/EPA/CORBIS]
Indicating Radiation Injury. Three Mile Island, Chernobyl, and Fukushima were catastrophic nuclear power plant accidents. The radiation from these accidents not only took an immediate toll on human lives, but will also persist long-term, as individuals will suffer from cancer, gut damage, and infections. On the cover, engineers at the Fukushima Daiichi Nuclear Power Plant fix the "ice wall" to reduce radiation-contaminated water from entering clean groundwater, and thus protect people from future radiation injury. In another effort to protect human health, Acharya et al. identified microRNAs associated with hematopoietic damage and long-term survival in mice exposed to different sublethal doses of total body irradiation. Such RNA signatures may distinguish humans with mild radiation-related injury from those with more severe (often nonrecoverable) bone marrow damage. Studies with human samples will allow for validation of such indicators, as well as investigation into new intervention measures, to improve patient care and to enhance survival after radiation exposure. [CREDIT: K. MAYAMA/EPA/CORBIS]

S. S. Acharya, W. Fendler, J. Watson, A. Hamilton, Y. Pan, E. Gaudiano, P. Moskwa, P. Bhanja, S. Saha, C. Guha, K. Parmar, D. Chowdhury, Serum microRNAs are early indicators of survival after radiation-induced hematopoietic injury. Sci. Transl. Med. 7, 287ra69 (2015).

Abstract

Accidental radiation exposure is a threat to human health that necessitates effective clinical planning and diagnosis. Minimally invasive biomarkers that can predict long-term radiation injury are urgently needed for optimal management after a radiation accident. We have identified serum microRNA (miRNA) signatures that indicate long-term impact of total body irradiation (TBI) in mice when measured within 24 hours of exposure. Impact of TBI on the hematopoietic system was systematically assessed to determine a correlation of residual hematopoietic stem cells (HSCs) with increasing doses of radiation. Serum miRNA signatures distinguished untreated mice from animals exposed to radiation and correlated with the impact of radiation on HSCs. Mice exposed to sublethal (6.5 Gy) and lethal (8 Gy) doses of radiation were indistinguishable for 3 to 4 weeks after exposure. A serum miRNA signature detectable 24 hours after radiation exposure consistently segregated these two cohorts. Furthermore, using either a radioprotective agent before, or radiation mitigation after, lethal radiation, we determined that the serum miRNA signature correlated with the impact of radiation on animal health rather than the radiation dose. Last, using humanized mice that had been engrafted with human CD34+ HSCs, we determined that the serum miRNA signature indicated radiation-induced injury to the human bone marrow cells. Our data suggest that serum miRNAs can serve as functional dosimeters of radiation, representing a potential breakthrough in early assessment of radiation-induced hematopoietic damage and timely use of medical countermeasures to mitigate the long-term impact of radiation.

La justice japonaise s'oppose au redémarrage d'un site nucléaire

14 Avril 2015,

Publié par Bioécologie

La justice japonaise s'est opposée à la remise en marche des réacteurs n°3 et n°4 de la centrale nucléaire de Takahama, gérée par la société Kansai Electric Power, donnant raison aux habitants de la région inquiets pour la sécurité des installations, ont fait savoir mardi les plaignants.

Il s'agit de la deuxième décision de justice en moins d'un an contre des réacteurs gérés par cet opérateur.

Les réacteurs de Takahama, situés dans la préfecture de Fukui, sur la côte de la mer du Japon, ont satisfait pourtant aux nouvelles réglementations sur la sécurité fixées par l'autorité de contrôle du nucléaire et devaient être remis en service dans le courant de l'année.

Des habitants de la région estiment en revanche que le projet de remise en service de la centrale de Takahama sous-estime le risque de séisme, ne se conforme pas aux règles de sécurité renforcées, et que les mesures d'évacuation prévues ne sont pas à la hauteur.

Selon la chaîne publique NHK, la justice a déclaré à l'appui de sa décision que la sécurité à la centrale de Takahama ne pouvait être garantie et que les normes fixées par l'autorité de contrôle n'étaient pas suffisamment "rationnelles".

En savoir plus sur Yahoo.fr

Des experts de l'AIEA vont revenir à Fukushima en raison des problèmes d'eau contaminée

31 Mars 2015,

Publié par Bioécologie

Un article du journal Le Monde.fr avec AFP | 31.03.2015

"Des experts de l'Agence internationale de l'énergie atomique (AIEA) vont revenir à la centrale accidentée de Fukushima en avril, à la demande des autorités nippones, en raison de nouveaux problèmes d'eau contaminée survenus après leur passage en février.

Les spécialistes de l'organisation devaient prochainement compiler un rapport final à la suite de leur précédente mission, mais les avaries récentes constatées nécessitent des explications complémentaires, a jugé le ministère de l'industrie japonais.

Lire : A Fukushima, l’interminable décontamination

Les experts seront au Japon du 17 au 21 avril pour rencontrer des responsables nippons de l'Agence de l'énergie ainsi que de la compagnie géante du site, Tokyo Electric Power (Tepco).

Des quantités importantes d'eau contaminée

Ils se rendront aussi directement dans le complexe atomique Fukushima Daiichi ravagé par le séisme et le tsunami du 11 mars 2011. Bien que des progrès aient été accomplis en vue du démantèlement, de très gros problèmes de gestion des quantités importantes d'eau contaminée sur le site demeurent.

Depuis le dernier passage sur place des équipes de l'AIEA, qui avaient salué le travail réalisé cette dernière année, de nouveaux pépins ont eu lieu, comme des débordements importants d'eau de pluie, la découverte d'une mare d'eau dans un des bâtiments du site ou encore la contamination, certes temporaire mais importante, de l'eau d'un canal traversant le site et descendant vers l'océan Pacifique voisin."

Lire la suite ici