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22 mars 2011 2 22 /03 /mars /2011 22:35

Fukushima Nuclear Accident Update (22 March 2011, 18:00 UTC)

Spent Fuel Pools at Fukushima Daiichi Nuclear Power Plant - Updated

Spent fuel removed from a nuclear reactor is highly radioactive and generates intense heat. This irradiated fuel needs to be actively cooled for one to three years in pools that cool the fuel, shield the radioactivity, and keep the fuel in the proper position to avoid fission reactions. If the cooling is lost, the water can boil and fuel rods can be exposed to the air, possibly leading to severe damage and a large release of radiation.

Nuclear power plants must replace fuel every one to two years, and the Fukushima Daiichi reactors typically remove about 25 percent of the reactor's fuel - to be replaced with fresh, or unirradiated, fuel - during each refuelling outage. The spent fuel, which is hottest immediately after it is removed from the reactor, is placed in the spent fuel pool until it is cool enough to be moved to longer-term storage.

The concern about the spent fuel pools at Fukushima Daiichi is that the capability to cool the pools has been compromised. See diagram below for location of the pool in each reactor building.

Elevated radiation measurements at the site may be partially of the result of uncovered or overheated spent fuel.

Number of Fuel Assemblies in Cooling Pools at Fukushima Daiichi
(Reported 17 March by Japan's Ministry of Economy, Trade and Industry)

  Capacity Irradiated Fuel Assemblies Unirradiated Fuel Assemblies Most Recent Additions of Irradiated Fuel
Unit 1 900 292 100 March 2010
Unit 2 1,240 587 28 Sept 2010
Unit 3 1,220 514 52 June 2010
Unit 4 1,590 1,331 204 Nov 2010
Unit 5 1,590 946 48 Jan 2011
Unit 6 1,770 876 64 Aug 2010

Here is a summary of spent fuel conditions at Fukushima Daiichi nuclear power plant, based on documents and confirmed by Japanese officials (new information in bold):

Unit 1

Unit 1 experienced an explosion on 12 March that destroyed the outer shell of the building's upper floors. No precise information has been available on the status of the spent fuel pool.

Unit 2

Precise information on the status of the spent fuel pool was unavailable in the days following the earthquake, but Japan's Nuclear and Industrial Safety Agency began to release temperature data on 20 March:

20 March, 23:00 UTC: 49 °C
21 March, 05:25 UTC: 50 °C
21 March, 21:20 UTC: 51 °C
22 March, 02:20 UTC: 53 °C
22 March, 06:30 UTC: 50 °C

Workers conducted an operation to spray 40 tonnes of seawater to the spent fuel pool on 20 March.

Unit 3

Unit 3 experienced an explosion on 14 March that destroyed the outer shell of the building's upper floors. The blast may have damaged the primary containment vessel and the spent fuel pool. Concerned by possible loss of water in the pool, authorities began spraying water into the building in an effort to replenish water levels. First, helicopters dropped seawater on 17 March, and every day since then, including 21 March, emergency workers have sprayed water from fire trucks and other vehicles, so far spraying at least 3,742 tonnes.

Unit 4

This reactor was shut down 30 November 2010 for routine maintenance, and all the fuel assemblies were transferred from the reactor to the spent fuel pool, before the 11 March earthquake. The heat load in this pool is therefore larger than the others.

On 14 March, the building's upper floors were severely damaged, possibly causing a reduction of cooling capability in the spent fuel pool. Emergency workers began spraying water into the building on 20 March, and have continued daily since then, so far spraying at least 255 tonnes.

Units 5 and 6

Instrumentation at these reactors began to indicate rising temperatures at their spent fuel pools starting on 14 March. Three days later, Japanese technicians successfully started an emergency diesel generator at Unit 6, which they used to provide power to basic cooling and fresh-water replenishment systems. Workers created holes in the rooftops of both buildings to prevent any hydrogen accumulation, which is suspected of causing earlier explosions at Units 1 and 3.

A second generator came online on 18 March, and the next day, the higher-capability Residual Heat Removal system recovered full function. Temperatures in the spent fuel pools of Units 5 and 6 have gradually returned to significantly lower temperatures (See graph below).

Common Use Spent Fuel Pool

In addition to pools in each of the plant's reactor buildings, there is another facility - the Common Use Spent Fuel Pool - where spent fuel is stored after cooling at least 18 months in the reactor buildings. This fuel is much cooler than the assemblies stored in the reactor buildings. Japanese authorities confirmed as of 18 March that fuel assemblies there were fully covered by water, and the temperature was 57 °C as of 20 March, 00:00 UTC. Workers sprayed water over the pool on 21 March for nearly five hours, and the Nuclear and Industrial Safety Agency reported that the pool temperature had risen to 61 °C as of 21 March, 07:30 UTC.

 

source IAEA

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22 mars 2011 2 22 /03 /mars /2011 22:26

 

Press Release (Mar 22,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 11:00 PM Mar 22nd)
 
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 11:00 PM Mar 22nd)

*new items are underlined

All 6 units of Fukushima Daiichi Nuclear Power Station have been shut
down.

Unit 1(Shut down)
-Reactor has been shut down. However, the explosive sound and white smoke
were confirmed after the big quake occurred at 3:36PM Mar 12th. It was
assumed to be hydrogen explosion.
-We have been injecting sea water into the reactor pressure vessel.

Unit 2(Shut down)
-Reactor has been shut down and the level of reactor coolant had dropped
and the reactor pressure had increased because the Reactor Core Isolation
Cooling System stopped. Measures were taken to lower the pressure within
the Reactor Containment Vessel and to inject sea water into the Reactor
while carefully confirming safety. The level of reactor coolant and the
pressure of the Reactor resumed.
-At approximately 6:00AM on March 15th, 2011, an abnormal noise began
emanating from nearby Pressure Suppression Chamber and the pressure
within this chamber decreased.
-We completed receiving electricity from the external transmission line
up to the auxiliary transformer. We installed the power cable from the
transformer to the temporary power panel. At 3: 46 PM, March 20th, we
started energizing the load-side power panel.
-At 6:20 on March 21st, white smoke was confirmed arising from the top
of the reactor building. As of 7:11 am on March 22nd, smoke decreased
to the level where we can hardly confirm
-We have been injecting sea water into the reactor pressure vessel.

Unit 3(Shut down)
-Reactor has been shut down. However, the explosive sound and white smoke
were confirmed at 11:01AM Mar 14th. It was assumed to be hydrogen
explosion.
-At 8:30AM on March 16th, fog like steam was confirmed arising from the
reactor building.
-At approximately 6:15AM on March 17th the pressure of the Suppression
Chamber has temporarily increased. We were preparing to implement a
measurement to reduce the pressure of the reactor containment vessel
(partial discharge of air containing radioactive material to outside)
in order to fully secure safety. However, at present, it is not a
situation to take a measure immediately to discharge air containing
radioactive material to outside now. We will continue to monitor the
status of the pressure of the reactor containment vessel.
-We are working on receiving external power supply to Units 3 and 4.
-At approximately 4:00 pm, March 21st, light gray smoke was confirmed
arising from the floor roof of the Unit 3 building. On March 22nd,
the color of smoke changed to somewhat white and it is slowly
dissipating.
-We have been injecting sea water into the reactor pressure vessel.

Unit 4 (outage due to regular inspection)
-Reactor has been shut down. However, at approximately 6AM on March 15th.
We have confirmed the explosive sound and the sustained damage around
the 5th floor rooftop area of the Nuclear Reactor Building.
-On March 15th and 16th, we respectively confirmed the outbreak of fire
at the 4th floor of the northwestern part of the Nuclear Reactor
Building. We immediately reported this matter to the fire department
and the related authorities. TEPCO employees confirmed that each fire
had already died down by itself.
-At this moment, we do not consider any reactor coolant leakage inside
the reactor containment vessel happened.

Unit 5 (outage due to regular inspection)
-Reactor has been shut down and the sufficient level of reactor coolant
to ensure safety is maintained.
-At 5 AM, March 19th, we started the Residual Heat Removal System Pump
(C ) in order to cool the spent fuel pool.
-At this moment, we do not consider any reactor coolant leakage inside
the reactor containment vessel happened.
-At 2:30 PM, March 20th, the reactor achieved reactor cold shutdown.

Unit 6 (outage due to regular inspection)
-Reactor has been shut down and the sufficient level of reactor coolant
to ensure safety is maintained.
-We are working on receiving external power supply to Units 5 and 6. We
completed the repair work on the emergency diesel generator (A).
-At 10:14 pm, March 19th, we started the Residual Heat Removal System
Pump (B ) of Unit 6 in order to cool the spent fuel pool.
-At this moment, we do not consider any reactor coolant leakage inside
the reactor containment vessel happened.
-At 7:27 PM, March 20th, the reactor achieved reactor cold shutdown.

Cooling of spent fuel pools
-In Unit 3, water discharge by Self-Defense Force's helicopters was
conducted from 9:48 AM in the morning on March 17th. Also water
discharge by the riot police's high-pressure water cannon trucks and
Self-Defense Force's fire engines was conducted from 7PM on March 17th
and finished at 8:09PM.
-In Unit 3, water discharge by Self-Defense Force's fire engines and US
army's fire engines was conducted from 2 PM and completed a quarter to
3 PM.
-After that, from 0:30 AM, Mar 19th, water discharge by Tokyo Fire
Department's Hyper Rescue was conducted to Unit 3 and completed at
1:10 AM. At around 2:10PM, water discharge by Tokyo Fire Department's
Hyper Rescue to Unit 3 was conducted once again. At approximately 3:40
am, they had finished water discharge.
-At approximately 8:21 am, March 20th, water discharge to Unit 4 by fire
engine has started with the cooperation of Self-Defense Forces and
finished at approximately 9:40 am. At approximately 6:45 pm, March 20th
water discharge to Unit 4 by Self-Defense's water cannon trucks was
conducted and finished at approximately 7:45 pm.
-From 3: 05 PM to 5: 20 PM on March 20th, 40 tons of seawater was
injected into Unit 2 by TEPCO employees.
-From 9:30 PM on March 20th, water discharge by Tokyo Fire Department's
Hyper Rescue was conducted to Unit 3 and completed at approximately 4:00
AM today.
-At approximately 6:30 AM today,, water discharge to Unit 4 was started
by Self-Defense Force's fire engines and US army's fire engines and was
finished at approximately 8:40 AM.
-From around 4:00 PM to 5:00 PM on March 22nd, approximately 18 tons of
seawater was injected into Unit 2 by TEPCO employees.
-From around 3:10 PM on March 22nd, water discharge into Unit 3 by Tokyo
Fire Department's Hyper Rescue and Osaka City Fire Department was
conducted and completed at approximately 4:00 PM on the same day. From
around 5:20 PM on March 22nd, water discharge into Unit 4 from the
concrete pumping vehicle was conducted and ended at around 8:30 PM on
the same day.
-We are considering further water discharge at other units and others
subject to the conditions of spent fuel pools.

Casualty
-2 workers of cooperative firm were injured at the occurrence of the
earthquake, and were transported to the hospital on March 11th.
-4 workers were injured and transported to the hospital after explosive
sound and white smoke were confirmed around the Unit 1on March 11th.
-Presence of 2 TEPCO employees at the site is not confirmed on March 11th.
-1 TEPCO employee who was not able to stand by his own holding left chest
with his hand, was transported to the hospital by an ambulance on March
12th.
-1 subcontract worker at the key earthquake-proof building was unconscious
and transported to the hospital by an ambulance on March 12th.
-The radiation exposure of 1 TEPCO employee, who was working inside the
reactor building, exceeded 100mSv and he was transported to the hospital
on March 12th.
-2 TEPCO employees felt bad during their operation in the central control
rooms of Unit 1 and 2 while wearing full masks, and were transferred to
Fukushima Daini Power Station for consultation with a medical advisor
on March 13th.
-11 workers were injured and transported to Fukushima Daini Nuclear Power
Station etc. after explosive sound and white smoke were confirmed around
the Unit 3.One of the workers was transported to the FUKUSHIMA Medical
University Hospital on March 14th.

Others
-We measured radioactive materials (iodine etc.) inside of the nuclear
power station area (outdoor) by monitoring car and confirmed that
radioactive materials level is getting higher than ordinary level.
As listed below, we have determined that specific incidents stipulated
in article 15, clause 1 of Act on Special Measures Concerning Nuclear
Emergency Preparedness (Abnormal increase in radiation dose measured
at site boundary) have occurred.
·Determined at 4:17 PM Mar 12th (Around Monitoring Post 4 )
·Determined at 8:56 AM Mar 13th (Around Monitoring Post 4 )
·Determined at 2:15 PM Mar 13th (Around Monitoring Post 4 )
·Determined at 3:50 AM Mar 14th (Around Monitoring Post 6 )
·Determined at 4:15 AM Mar 14th (Around Monitoring Post 2 )
·Determined at 9:27 AM Mar 14th (Around Monitoring Post 3 )
·Determined at 9:37 PM Mar 14th (Around main entrance )
·Determined at 6:51 AM Mar 15th (Around main entrance )
·Determined at 8:11 AM Mar 15th (Around main entrance )
·Determined at 4:17 PM Mar 15th (Around main entrance )
·Determined at 11:05 PM Mar 15th (Around main entrance )
·Determined at 8:58 AM Mar 19th (Around MP5)
From now on, if the measured figure fluctuates and goes above and below
500 micro Sv/h, we deem that as the continuous same event and will not
regard that as a new specific incidents stipulated in article 15, clause
1 of the Act on Special Measures Concerning Nuclear Emergency Preparedness
(Abnormal increase in radiation dose measured at site boundary) has
occurred. In the interim, if we measure a manifestly abnormal figure and
it is evident that the event is not the continuous same event, we will
determine and notify.

-The national government has instructed evacuation for those local
residents within 20km radius of the periphery and evacuation to inside
for those residents from 20km to 30km radius of the periphery, because
it's possible that radioactive materials are discharged.
-At approximately 10AM on March 15th, we observed 400mSv/h at the inland
side of the Unit 3 reactor building and 100mSv/h at the inland side of
the Unit 4 reactor building.
-We checked the status of spent fuel in the common pool, and confirmed
that the water level secured. We are planning to conduct a detailed
inspection.
-We found no signs of abnormal situation for the casks by visual
observation during the patrol activity. A detailed inspection is under
preparation.
-At Units 5 and 6, in order to prevent hydrogen gas from accumulating
within the buildings, we have made three holes on the roof of the
reactor building for each unit.
-In total 12 fire engines are lent for the water discharge to the spent
fuel pools and water injection to the nuclear reactors by various
regional fire departments* as well as Tokyo Fire Department.
*: Koriyama Fire Department, Iwaki Fire Brigade Headquarters, Fire
Headquarters of Sukagawa District Wide Area Fire-fighting
Association, Yonezawa City Fire Headquarters, Utsunomiya City
Fire Headquarters, Fire Headquarters of Aizu-Wakamatsu wide area
municipal association, Saitama City Fire Bureau, and Niigata City
Fire Bureau.
-On March 21st and 22nd, we detected cobalt, iodine and cesium from
the seawater around discharge canal of Unit 1, 2, 3 and 4.
-We detected iodine and cesium in the air collected at the site of
Fukushima Daiichi Nuclear Power Station on March 20th and 21st.
-We will continue to take all measures to ensure the safety and to
continue monitoring the surrounding environment around the Power
Station.

 

Source : TEPCO

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22 mars 2011 2 22 /03 /mars /2011 22:19

Communiqué de presse n°17 du mardi 22 mars 2011 à 10h00

Séisme au Japon
L’ASN fait le point sur la situation de la centrale nucléaire de Fukushima Daiichi :
Les travaux en vue de rétablir l’alimentation électrique se poursuivent mais la mise sous tension n’est pas réalisée

Paris, le 22/03/2011 10:27      

I. Situation de la centrale de Fukushima

 

Le maintien d’un niveau minimum d’eau dans les piscines reste une priorité. Les piscines des réacteurs n°3 et 4 font l’objet de manière intermittente d’aspersion massive d’eau de mer à l’aide d’un canon à eau.

 

La situation des cœurs des réacteurs 1, 2 et 3 reste identique à celle des derniers jours. L’injection d’eau de mer se poursuit, mais les combustibles sont significativement endommagés et restent en partie hors d’eau. L’exploitant japonais TEPCO n’aurait plus procédé à des décompressions volontaires des enceintes depuis 4 jours.

 

TEPCO poursuit ses efforts pour rétablir l’utilisation des moyens plus robustes de refroidissement. Le 22 mars, les réacteurs n°1, 2, 5 et 6 ont été connectés au réseau électrique externe. Les réacteurs n°5 et 6 sont sous tension. Des vérifications (pompes, tableaux électriques,…) sont en cours pour les réacteurs n°1 et 2 avant la mise sous tension. Le réacteur n°4 aurait été relié au réseau électrique externe à midi, heure locale. TEPCO estime pouvoir relier également le réacteur n°3 au réseau aujourd’hui.

 

De la fumée blanche s’est échappée du réacteur n°2 le 21 mars en fin d’après-midi (heure locale). Ce dégagement a coïncidé avec une hausse de la mesure de radioactivité située à l’entrée du site. De la fumée noire puis grisâtre s’est également échappée pendant quelques heures du réacteur n°3. Le personnel se trouvant à proximité a été évacué. Des fumées blanches seraient toujours visibles le 22 mars, à 9h30, heure locale, mais l’origine de ces dégagements de fumée est inconnue. Le personnel a été autorisé à revenir sur le site depuis 14h (heure locale).

 

II. Conséquences radiologiques de l’accident

 

Au large de Fukushima, des prélèvements d’eau de mer ont été réalisés à 100 m de la berge, les résultats montrent des niveaux en iode 131, de l’ordre de 100 fois supérieurs à la norme japonaise fixée à 0,04 Bq/cm3.

 

Les rejets ont entraîné des dépôts de radioactivité au sol et sur les végétaux dans la région de Fukushima. Les premières mesures réalisées par les autorités japonaises indiquent une contamination en Iode 131 et en césium de l’eau, des végétaux et des aliments, conduisant à dépasser dans certains cas les valeurs admissibles pour les denrées alimentaires définies par la réglementation japonaise. Les valeurs les plus élevées sont relevées dans les légumes à feuilles comme les épinards.

 

La radioactivité relevée par les balises de mesure à Tokyo reste faible et ne nécessite pas d’action particulière de protection des populations. La présence d’iode 131 a été mise en évidence dans le réseau d’eau potable de la région de Tokyo, mais avec une très faible concentration ne présentant pas de risque pour la santé.

 

Les masses d’air très faiblement contaminées, avec des niveaux de l’ordre de 1 000 à 10 000 fois inférieurs à ceux relevés suite à l’accident de Tchernobyl, devraient atteindre mercredi la France métropolitaine sans aucune conséquence sur la santé des personnes. La radioactivité ne devrait d’ailleurs pas être détectable par les balises du réseau Téléray de surveillance français de la radioactivité ambiante. Le système de surveillance géré par l’IRSN permettant de détecter instantanément l’augmentation de la radioactivité dans l’air est consultable sur le site internet de l’IRSN www.irsn.fr.

 

Le contrôle des produits frais (fraîchement emballés) en provenance du Japon est opérationnel, mais les flux de ces marchandises en provenance du Japon (fruits, légumes, algues) sont interrompus, pour le moment.

 

Aucune mesure de précaution particulière n’est à prendre pour le public ou les personnes fragiles tant en France métropolitaine que dans les départements et territoires d’outre mer.

 

Source ASN

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22 mars 2011 2 22 /03 /mars /2011 22:12
1 - La surveillance de la radioactivité de l’air en France

Depuis le 12 mars 2011, le panache radioactif qui résulte des rejets des réacteurs nucléaires accidentés de la centrale de Fukushima se déplace, tout en se diluant, dans les courants atmosphériques de l’hémisphère nord. L’IRSN dispose d’une modélisation de cette dispersion, réalisée en collaboration avec Météo France, qui lui permet de suivre et d’anticiper ce déplacement.

 

Selon cette modélisation, le panache a recouvert dans la journée du vendredi 18 mars 2011 la plus grande partie de l’Amérique du Nord et le nord-est de la Sibérie. Il est passé ensuite sur l’Atlantique Nord et pourrait atteindre la France métropolitaine le 23 ou 24 mars 2011. 

 

Les concentrations attendues de césium 137 dans l’air sur les territoires balayés par le panache sont extrêmement faibles. Ce radionucléide est représentatif des matières radioactives rejetées à longue distance lors d’un accident nucléaire.

 

Ces concentrations seront d’un niveau trop faible pour être détectées par les 170 balises d’alerte du réseau Téléray de l’IRSN, dont les mesures sont également consultables sur le site internet de l’IRSN.

 

Accéder aux cartes des résultats de mesure de la radioactivité de l'air :

 

   - en France métropolitaine
   - à Saint-Pierre-et-Miquelon
   - à Tahiti
   - en Guyane
   - en Guadeloupe
   - en Martinique
   - à La Réunion
   - en Nouvelle-Calédonie

 

L’IRSN partage l’avis de l’Agence de l’Environnement des Etats-Unis (EPA), qui estime que ces concentrations seront sans conséquence sanitaire et environnementale. De plus, elles seront si minimes qu’elles ne pourront sans doute être détectées dans l’environnement que par des mesures d’échantillons effectuées dans des laboratoires spécialisés.

 

L’IRSN dispose de ce type de laboratoires en métropole (ainsi qu’à Tahiti, situé dans l’hémisphère sud et donc hors du flux principal de ce panache). L’Institut publiera les résultats d’analyse dès que disponible, c'est-à-dire plusieurs jours après le passage du panache. S’agissant de Saint-Pierre-et-Miquelon ou des Antilles, les résultats des données analysées aux Etats-Unis sont considérées comme représentatifs de la situation sur ces territoires. 

2 - Modélisation de la dispersion des rejets radioactifs dans l’atmosphère à l’échelle mondiale

 

A partir des rejets estimés par l’IRSN, Météo France a simulé la dispersion des rejets radioactifs à très grande distance, projetée jusqu’au 26 mars.


Visionner la simulation

 

Selon cette simulation, le panache radioactif aurait actuellement atteint le nord-est de la Sibérie, les Etats-Unis et l’ouest de l’atlantique. Il devrait atteindre la France à partir du 23 ou 24 mars.

 

Les concentrations attendues à terme, d’après cette modélisation, pourraient être de l’ordre de 0,001 Bq/m3 en France métropolitaine et dans les départements d’outre-mer de l’hémisphère nord. Comme attendu, l’hémisphère sud n’est pas significativement affecté par cette dispersion à grande échelle.

 

A titre de comparaison, les valeurs mesurées au cours des jours suivant l’accident de Tchernobyl étaient dépassaient 100 000 Bq/m3 dans les premiers kilomètres autour de la centrale ; elles étaient de l’ordre de 100 à 1000 Bq/m3 dans les pays les plus touchés par le panache radioactif (Ukraine, Biélorussie) ; en France, les valeurs mesurées dans l’Est étaient de l’ordre de 1 à 10 Bq/m3 (le 1er mai 1986). Aujourd’hui, une très faible activité de césium 137 subsiste dans l’air, de l’ordre de 0,000001 Bq/m3.

 

Pour estimer ces niveaux de contamination de l’air, l’IRSN a dû au préalable évaluer la quantité de radioactivité qui a pu être rejetée du 12 au 22 mars 2011 par les trois réacteurs accidentés.

En savoir plus

 

 

Des mesures de précaution sont-elles nécessaires?


Il n’y a aucune mesure à prendre lorsque les masses d’air en provenance du Japon arriveront au dessus de la France.

 

En effet, en l’état actuel, les retombées radioactives consécutives au passage des masses d’air en provenance du Japon devraient être 1000 à 10000 fois inférieures à ce qui a été observé en France après l’accident de Tchernobyl.

 

Ces retombées seront sans conséquence pour la santé des Français et pour l'environnement. Aucune précaution particulière n’est à prendre pour les adultes, femmes enceintes et les enfants : pas de restriction alimentaire, pas de prise d’iode stable, pas de mise à l’abri ou de confinement.

 

Nous attirons votre attention sur le fait que la prise d’iode stable doit se faire uniquement sur ordre du Préfet et qu’il est dangereux d’ingérer des comprimés d’iode stable lorsque la situation ne l’exige pas.


Et en cas de pluie ?


La présence de pluies peut augmenter les dépôts consécutifs au passage des masses d’air en provenance du Japon. Cependant, même en présence de pluies, les retombées seront très faibles et ne nécessitent pas de précautions particulières.

  


Les eaux de pluie feront l’objet de mesures par l’IRSN, sans qu’une contamination significative de ces eaux ne soit attendue.

Aucune contamination des nappes phréatiques n’est attendue en France.

 

 

3 - Comprendre

 

Foire aux questions thématiques

Afin de répondre le plus synthétiquement possible aux questions que vous vous posez, nous produisons des foires aux questions concernant le séisme au Japon et ses impacts sur les installations nucléaires.

Pour toute autre question, vous pouvez nous faire parvenir un mail via notre boite contact.

 

Télécharger la foire aux questions mise à jour le 21 mars (document pdf)

 

> Vous trouverez également une foire aux questions sur le site du Ministère de la Santé : Japon - Point sur les recommandations sanitaires. 

 

 

Informations générales sur les installations nucléaires et la surveillance de la radioactivité de l'environnement

 

Découvrez quelques dossiers d'informations de notre Base de connaissances :

L'organisation de la surveillance de la radioactivité de l’environnement en France
L'accident de Three Mile Island
L'accicent de Tchernobyl
Risque sismique et installations nucléaires

L’organisation de la sûreté nucléaire en France
L’échelle INES

 

Conséquences environnementales d'un rejet radioactif accidentel et voie d'exposition des personnes (document pdf)

 

 

Les alimentations électriques sur une centrale nucléaire française
Une centrale nucléaire produit de l’électricité. Néanmoins elle a besoin d’une alimentation électrique pour assurer son bon fonctionnement ainsi que l’ensemble des ses mesures de sureté. Mais qu’en est-il des centrales nucléaires françaises ?

Télécharger la fiche d'information au format PDF

 

La gestion d’un accident grave sur un réacteur à eau sous pression en France
Même si les accidents graves sont rares, des mesures sont prises afin de gérer leurs conséquences. Voici un descriptif succint des mesures prises en cas d’accident grave en France.

Télécharger la fiche d'information au format PDF

 

Source IRSN

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22 mars 2011 2 22 /03 /mars /2011 21:22

Deux journées de championnat, et déjà une trêve.

Avant que certains joueurs du championnat russe ne rejoignent leur sélection, notamment en vue des éliminatoires de l'Euro et de la CAN 2012, focus sur la deuxième journée.
Une journée qui a commencé ce samedi avec la victoire du FK Krasnodar sur le Spartak Naltchik (2-0), une victoire historique car étant la première du FK Krasnodar en Premier-Liga. Plus tard dans la journée, le Dynamo Moscou a obtenu sa première victoire de la saison en battant Rostov (3-1).
Dimanche, c'était au tour d'un autre promu, autre club de Krasnodar accessoirement, d'enter en scène. Le Kouban (c'est de lui qu'il s'agit) s'est imposé sur le terrain du Tom Tomsk (1-0) qui concède sa deuxième défaite en autant de matchs. Le Lokomotiv Moscou s'est quant à lui incliné sur le terrain de l'Amkar Perm (0-1) alors que le Roubine Kazan parvenait à venir à bout du Terek Grozny (2-0). Une victoire qui permet aux Tatars, champions en 2008 et 2009, de s'installer en tête. Grozny et Tomsk sont quant à eux les deux lanternes rouges et les seules équipes à avoir perdu leurs deux premiers matchs.
La journée se clôturait ce lundi avec les rencontres des équipes engagées en Ligue Europa. On n'a malheureusement pas pu tester la capacité de réaction du CSKA Moscou, éliminé jeudi soir à Porto (1-2 après avoir perdu 0-1 à l'aller). En raison d'une pelouse impraticable à Samara, le match entre l'ancien club de l'Armée rouge et le Krylya Sovetov Samara a du être reporté. Éliminé par Twente malgré sa victoire lors du match retour (2-0, insuffisant pour rattraper le 0-3 de l'aller), le Zenit Saint-Pétersbourg s'est rattrapé en battant l'Anji Makhatchkala (2-0). Une deuxième victoire en autant de matchs qui lui permet de rejoindre le Roubine Kazan en tête. Dernière équipe russe encore engagée dans les compétitions européennes (vainqueur de l'Ajax Amsterdam 3-0 et 1-0 à l'aller), le Spartak Moscou a obtenu sa première victoire de la saison en battant sur le fil le Volga Nijni Novgorod (1-0).



Résultats :
FK Krasnodar 2-0 Spartak Naltchik
(Buts : Igor Picuşceac (35'), Yura Movsisyan (70'))
Dynamo Moscou 3-1 FK Rostov
(DYN : Leandro Fernández (50'), Zvjezdan Misimović (74' sp), Andreï Voronine (90') ; ROS : Anri Khagouch (85'))
Tom Tomsk 0-1 Kouban Krasnodar
(Sergueï Davydov (83'))
Amkar Perm 1-0 Lokomotiv Moscou
(Stevica Ristić (25'))
Roubine Kazan 2-0 Terek Grozny
(Gökdeniz Karadeniz (33'), Christian Noboa (57'))
Krylya Sovetov Samara – CSKA Moscou
Reporté
Zenit Saint-Pétersbourg 2-0 Anji Makhatchkala
(Roman Chirokov (6'), Danko Lazović (45'+2'))
Spartak Moscou 1-0 Volga Nijni Novgorod
(Welliton (50'))

Classement :
(Points, matchs joues, victoires, nuls, defaites, buts marques, buts encaisses, difference de buts)
1. Roubine Kazan (6, 2, 2, 0, 0, 4, 0, +4)
2. Zenit Saint-Pétersbourg (6, 2, 2, 0, 0, 3, 0, +3)
3. FK Krasnodar (4, 2, 1, 1, 0, 2, 0, +2)
4. FK Rostov (3, 2, 1, 0, 1, 5, 3, +2)
5. CSKA Moscou (3, 1, 1, 0, 0, 2, 0, +2)
6. Dynamo Moscou (3, 2, 1, 0, 1, 5, 4, +1)
7. Volga Nijni Novgorod (3, 2, 1, 0, 1, 2, 1, +1)
8. Lokomotiv Moscou (3, 2, 1, 0, 1, 3, 3, 0)
--------------------------------------------------------------------------------------------
9. Amkar Perm, Kouban Krasnodar, Spartak Naltchik (3, 2, 1, 0, 1, 1, 2, -1)
12. Spartak Moscou (3, 2, 1, 0, 1, 1, 4, -3)
13. Anji Makhatchkala (1, 2, 0, 1, 1, 0, 2, -2)
14. Krylya Sovetov Samara (0, 1, 0, 0, 1, 0, 1, -1)
15. Terek Grozny, Tom Tomsk (0, 2, 0, 0, 2, 0, 3, -3)

Buteurs :
1. Sergueï Ignachevitch (CSKA Moscou) ; Roman Adamov (FK Rostov) ; Christian Noboa (Roubine Kazan) ; Danko Lazovi
ć (Zenit Saint-Pétersbourg) : 2 buts
5. Stevica Ristić (Amkar Perm) ; Leandro Fernández, Kevin Kurányi, Zvjezdan Misimović, Alexandr Samedov, Andreï Voronine (Dynamo Moscou) ; Yura Movsisyan, Igor Picuşeac (FK Krasnodar) ; Sergueï Davydov (Kouban Krasnodar) ; Taras Bourlak, Jan
Ďurica, Dmitri Torbinski (Lokomotiv Moscou) ; Dragan Blatnjak, Timofeï Kalatchev, Anri Khagouch (FK Rostov) ; Gökdeniz Karadeniz, Alan Kassaev (Roubine Kazan) ; Welliton (Spartak Moscou) ; Leandro (Spartak Naltchik) ; Sergueï Bendz, Otar Martsvaladze (Volga Nijni Novgorod) ; Roman Chirokov (Zenit Saint-Pétersbourg) : 1 but

Prochaine journée :
2 avril :Lokomotiv Moscou – FK Rostov
Volga Nijni Novgorod – Dynamo Moscou
Amkar Perm – Krylya Sovetov Samara
3 avril :Anji Makhatchkala – Roubine Kazan
Spartak Naltchik – Zenit Saint-Pétersbourg
CSKA Moscou – FK Krasnodar
Kouban Krasnodar – Spartak Moscou
4 avril :Terek Grozny – Tom Tomsk

 

Karim

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22 mars 2011 2 22 /03 /mars /2011 15:57

L'attaquant de l'OM, Brandão, subit des examens médicaux ce matin et sera présenté officiellement à la presse, comme le nouveau renfort du Cruzeiro pour la saison 2011, cet après-midi  mardi, à 15h30, dans le Terrier du Renard II. Le joueur viendra en prêt jusqu'à décembre 2011.

 

Source : Site Oficial do Cruzeiro

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21 mars 2011 1 21 /03 /mars /2011 16:42

Voici ce que vous lirez en passant votre souris sur le point bleu près de Marseille sur la carte IRSN :

http://www.irsn.fr/FR/Documents/france.htm

Marseille Date de la mesure : 21/03/2011 à 14h25

débit de dose 60 nanoSievert par heure.

Moyenne 2010 : 71 +/- 30%

 

Voilà un site à suivre cette semaine ! (sans être trop inquiets, mais l'info étant disponible, autant regarder de près).

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18 mars 2011 5 18 /03 /mars /2011 23:32

Fri Mar 18, 2011 4:57pm EDT

 

TOKYO (Reuters) - Exhausted engineers attached a power cable to the outside of Japan's tsunami-crippled nuclear station on Saturday in a race to prevent deadly radiation from an accident now rated at least as bad as America's Three Mile Island in 1979.

 

Further cabling inside was underway before an attempt to restart water pumps needed to cool overheated nuclear fuel rods at the six-reactor Fukushima plant in northeastern Japan, 240 km (150 miles) north of Tokyo.

 

Japan's unprecedented multiple crisis of earthquake, tsunami and radiation leak has unsettled world financial markets, prompted international reassessment of nuclear safety and given the Asian nation its sternest test since World War Two.

 

It has also stirred unhappy memories of Japan's past nuclear nightmare -- the U.S. atomic bombs dropped on Hiroshima and Nagasaki in 1945.

 

Working inside a 20 km (12 miles) evacuation zone at Fukushima, nearly 300 engineers were focused on trying to restore power at pumps in four of the reactors.

 

"TEPCO has connected the external transmission line with the receiving point of the plant and confirmed that electricity can be supplied," the plant's operator Tokyo Electric Power Co said in a statement.

 

Another 1,480 meters (5,000 feet) of cable are being laid inside the complex before engineers try to crank up the coolers at reactor No. 2, followed by 1, 3 and 4 this weekend, company officials added.

 

Should that work , it will be a turning point.

 

"If they can get those electric pumps on and they can start pushing that water successfully up the core, quite slowly so you don't cause any brittle failure, they should be able to get it under control in the next couple of days," said Laurence Williams, of Britain's University of Central Lancashire.

 

If not, there is an option of last resort under consideration to bury the sprawling 40-year-old plant in sand and concrete to prevent a catastrophic radiation release.

 

That method was used to seal huge leakages from the 1986 Chernobyl disaster.

 

Underlining authorities' desperation, fire engines sprayed water overnight in a crude tactic to cool reactor No. 3, considered the most critical because of its use of mixed oxides, or mox, containing both uranium and highly toxic plutonium.

 

Japan has raised the severity rating of the nuclear crisis from level 4 to level 5 on the seven-level INES international scale, putting it on a par with the Three Mile Island accident in 1979, although some experts say it is more serious.

 

Chernobyl, in Ukraine, was a 7 on that scale.

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18 mars 2011 5 18 /03 /mars /2011 23:26

Monitoring outputs by MEXT out of 20km Zone of Fukushima Dai-ichi NPP and Dai-ni NPP
MEXT is monitoring the radiation dose rate out of 20km Zone of Fukushima Dai-ichi NPP and Dai-ni NPP and deliver the output as needed for the safety of the evacuees and the residents in the vicinity.  
Readings at Monitoring Post out of 20 Km Zone of Fukushima Dai-ichi NPP

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18 mars 2011 5 18 /03 /mars /2011 23:22

March 18, 2011
Nuclear and Industrial Safety Agency
Seismic Damage Information (the 31st Release)
(As of 22:00 March 18th, 2011)
Nuclear and Industrial Safety Agency (NISA) confirmed the current situation of Onagawa NPS, Tohoku Electric Power Co. Inc.; Fukushima Dai-ichi and Fukushima Dai-ni NPSs, Tokyo Electric Power Co. Inc. (TEPCO); Tokai Dai-ni NPS, Japan Atomic Power Co. Inc. as follows:
Major updates are as follows.
1. Nuclear Power Stations (NPS)
 Fukushima Dai-ichi NPS
<Situation of Water Spray>
・ Hyper Rescue of Tokyo Fire Department arrived at the Main Gate and started an entrance procedure for the preparation of water spray. (23:30 March 18th)
< Recovery of the power supply >
・ A survey was started for the connection to the external power supply for each unit. (23:00 March 18th)
[Unit 1 & 2]
Work for switchboard and cabling is scheduled until March 19th in order to secure external power supply.
[Unit 2]
Access to the substation for reserve power supply from external transmission line was completed and cable connection is under preparation.
[Unit 3,4,5 & 6]
Work for switchboard and cabling is scheduled until March 20th in order to secure external power supply.
2. Action taken by NISA and other agencies
[March 18th]
2
15:55 TEPCO reported to NISA Accidents and Failures with regard to Fukushima Dai-ichi Unit 1,2,3&4 (Leakage of the radioactive materials inside of the reactor building to non-controlled area) pursuant to the Paragraph 3, the Article 62 of the Nuclear Regulation Act.
16:48 JAPCO reported to NISA Accidents and Failures with regard to Tokai Unit 2 (Failure of the seawater pump moter of the emergency diesel generator 2C) pursuant to the Paragraph 3, the Article 62 of the Nuclear Regulation Act.
1. The status of operation at NPS (Number of automatic shutdown units: 10)
 Fukushima Dai-ichi NPS, TEPCO (Okuma Town and FutabaTown, Futaba County, Fukushima Prefecture)
(1) The status of operation
Unit 1 (460MWe): automatic shutdown
Unit 2 (784MWe): automatic shutdown
Unit 3 (784MWe): automatic shutdown
Unit 4 (784MWe): in periodic inspection outage
Unit 5 (784MWe): in periodic inspection outage
Unit 6 (1,100MWe): in periodic inspection outage
(2) Major Plant Parameters (22:00 March 18th)
Unit 1
Unit 2
Unit 3
Unit 4
Unit 5
Unit 6
Reactor Pressure*1
[MPa]
0.295(A)
0.252(B)
0.096(A)
0.081(B)
0.085 (A)
0.117(B)

1.767
0.674
CV Pressure
(D/W) [kPa]
180*3
140
160



Reactor Water Level*2 [Mm]
-1,750(A)
-1,800(B)
-1,400(A)
Not available(B)
-1,900(A)
-2,300(B)

1,922
2,364
Suppression Pool Water Temperature
(S/C) [℃]






Suppression Pool Pressure
(S/C) [kPa]
160
down scale
down scale



3
Spent Fuel Pool Water Temperature
[℃]



84
67.6
65
Time of Measurement
21:10
March 18th
21:10
March 18th
21:05
March 18th
04:08
March 14th
21:00
March 18th
21:00
March 18th
*1: Converted from reading value to absolute pressure
*2: Distance from the top of fuel
*3: Recovered
(3) Report concerning other incidents
・ TEPCO reported to NISA the event in accordance with the Article 10 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Fukushima Dai-ichi. (15:42 March 11th)
・ TEPCO reported to NISA the event (Loss of reactor cooling function) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Units 1 and 2 of Fukushima Dai-ichi. (16:36 March 11th)
・ The cable for receiving electricity from the transmission line of Tohoku Electric Power Company was installed. It is scheduled to be connected to Unit 2 after the completion of discharge work. (17:30 March 17th) The content of operations for recovery of external power supply to Unit 1 to 4 (Power supply from Electric transmission grid of Tohoku Electric Power Co., and from the route via transformer sub-station of TEPCO) is being confirmed. (06:30 March 18th)
<Unit 1>
・ Seawater was injected to RPV via the Fire Extinguishing System Line (Started up 11:55 March 13th) →Temporary interruption of the injection (01:10 March 14th)
・ The sound of explosion in Unit 1 occurred. (15:36 March 12nd)
・ Seawater is being injected. (22:00 March 18th)
<Unit 2>
・ Water injection function was sustained. (14:00 March 13th)
・ The Blow-out Panel of reactor building was opened due to the explosion of the Unit 3 reactor building. (After 11:00 March 14th)
4
・ Reactor water level was decreasing. (13:18 March 14th) TEPCO reported to NISA the event (Loss of reactor cooling functions) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness. (13:49 March 14th)
・ Seawater injection to RPV was ready through the Fire Extinguishing System line. (19:20 March 14th)
・ TEPCO evaluated core damage of Unit 2 was “less than 5%” (22:14 March 14th)
・ Water level in RPV in Unit 2 is decreasing. (22:50 March 14th)
・ A sound of explosion was made in Unit 2. As the pressure in Suppression Chamber decreased (06:10 March 15th), there was a possibility that an incident occurred in the Chamber. (06:20 March 15th)
・ Access to the substation for reserve power supply from external transmission line was completed and cable connection is under preparation. (22:00 March 18th)
・ Seawater injection to RPV continued. (22:00 March 18th)
・ White smoke continues to be generated from the Blow-out Panel of reactor building.(22:00 March 18th)
<Unit 3>
・ Fresh water was injected to RPV via the Fire Extinguishing System Line (FESL). (11:55 March 13th)
・ Seawater was injected to RPV via FESL. (13:12 March 13th)
・ Injection of seawater for Unit 1 and Unit 3 to the Primary Containment Vessel (PCV) was interrupted due to the lack of seawater in pit. (01:10 March 14th)
・ For Unit 3 injection of seawater into PCV was restarted (03:20 March 14th)
・ The pressure in PCV of Unit 3 rose unusually. (7:44 March 14th) TEPCO reported to NISA the event (Loss of reactor cooling function) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness. (7:52 March 14th)
・ For Unit 3 the explosion like Unit 1 occurred around the Reactor Building (11:01 March 14th)
・ The white smoke like steam generated from Unit 3. (08:30 March 16th)
5
・ Because of the possibility that PCV of Unit 3 was damaged, the workers evacuated from the central control room of Unit 3 and 4 (common control room). (10:45 March 16th) Thereafter the operators returned to the room and restarted the operation for water injection. (11:30 March 16th)
・ Seawater was discharged 4 times to Unit 3 by the helicopters of the Self-Defence Force. (9:48, 9:52, 9:58 and 10:01 March 17th)
・ The riot police arrived at the site for grand discharge. (16:10 March 17th)
・ The Self-Defence Force started the water spray from 19:35 March 17th.
・ The water spray from the ground was carried out by the riot police (from 19:05 till 19:13 March 17th)
・ The water spray from the ground was carried out by the Self-Defence Force using 5 cars (March 17th)
(The starting time of water spray by each car: 19:35, 19:45, 20:00 and 20:07 March 17th)
・ The water spray from the ground using 6 fire engines (6 tons of water per car) was carried out by the Self-Defence Force. (from before 14:00 till 14:38 March 18th)
・ The water spray from the ground using a fire engine provided by the US Military was carried out. (finished at 14:45 March 18th)
・ Seawater is being injected to RPV. White Smoke continues to be generated. (22:00 March 18th)
・ Hyper rescue vehicles (30 cars) started entrance procedure for the preparation of water spray. (23:30 March 18th)
<Unit 4>
・ It was confirmed that a part of wall in the operation area of Unit 4 was damaged. (06:14 March 15th)
・ The fire at Unit 4 occurred. (09:38 March 15th) TEPCO reported that the fire was extinguished spontaneously. (11:00 March 15th)
・ The temperature of water in the Spent Fuel Storage Pool at Unit 4 had increased. (84 ℃ at 04:08 March 14th)
・ The fire occurred at Unit 4. (5:45 March 15th) TEPCO reported that no fire could be confirmed on the ground.(06:15 March 16th)
・ Because of the replacement work of the Shroud of RPV, no fuel was
6
inside the PRV. White Smoke continues to be generated (22:00 March 18th)
<Units 5 and 6>
・ Emergency Diesel Generator (1 unit) for Unit 6 is operable and supplying electricity to Units 5 and 6. Water injection to the PRV and Spent Fuel Pool through MUWC is progressing.
<Spent Fuel Storage Facility>
・ It was confirmed that the water level of spent fuel storage pool was maintained full at after 06:00 March 18.
・ As of 11:19 March 18th, the water temperature in the pool is 55℃.
 Fukushima Dai-ni NPS (TEPCO) (Naraha Town / Tomioka Town, Futaba County, Fukushima Prefecture.)
(1) The status of operation
Unit1 (1,100MWe): automatic shutdown, cold shut down at 17:00, March 14th
Unit2 (1,100MWe): automatic shutdown, cold shut down at 18:00, March 14th
Unit3 (1,100MWe): automatic shutdown, cold shut down at 12:15, March 12th
Unit4 (1,100MWe): automatic shutdown, cold shut down at 07:15, March 15th
(2) Major plant parameters (As of 21:00 March 18th)
Unit
Unit 1
Unit 2
Unit 3
Unit 4
Reactor Pressure*1
MPa
0.18
0.11
0.13
0.15
Reactor water temperature

39.7
35.8
27.6
33.2
Reactor water level*2
Mm
10,596
9,996
7,501
9,026
Suppression pool water

29
25
42
32
7
temperature
Suppression pool pressure
kPa
(abs)
144
117
128
121
Remarks
cold shutdown
cold shutdown
cold shutdown
cold shutdown
*1:Converted from reading value to absolute pressure
*2: Distance from the top of fuel
(3) Report concerning other incidents
・ TEPCO reported to NISA the event in accordance with the Article 10 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Unit 1 of Fukushima Dai-ni NPS. (18:08 March 11th)
・ TEPCO reported to NISA the events in accordance with the Article 10 regarding Units 1, 2 and 4 of Fukushima Dai-ni NPS. (18:33 March 11th)
・ TEPCO reported to NISA the event (Loss of pressure suppression function) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Unit 1 of Fukushima Dai-ni NPS. (5:22 March 12th)
・ TEPCO reported to NISA the event (Loss of pressure suppression function) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Unit 2 of Fukushima Dai-ni NPS. (5:32 March 12th)
・ TEPCO reported to NISA the event (Loss of pressure suppression function) falling under the Article 15 of the Act on Special Measures Concerning Nuclear Emergency Preparedness regarding Unit 4 of Fukushima Dai-ni NPS. (6:07 March 12th)
 Onagawa NPS (Tohoku Electric Power Co. Inc.)
(Onagawa Town, Oga County and Ishinomaki City, Miyagi Prefecture)
(1) The status of operation
Unit 1 (524MWe): automatic shutdown, cold shut down at 0:58, March 12th
Unit 2 (825MWe): automatic shutdown, cold shut down at earthquake
Unit 3 (825MWe): automatic shutdown, cold shut down at 1:17, March
8
12th
(2) Readings of monitoring post
Reading of monitoring post:
MP2 (Monitoring at the North End of Site Boundary)
approx. 6,500 nGy/h (19:00 March 14th) →approx. 5,400 nGy/h (19:00 March 15th)
(3) Report concerning other incidents
・ Fire Smoke on the first basement of the Turbine Building was confirmed to be extinguished. (22:55 on March 11th)
・ Tohoku Electric Power Co. reported to NISA in accordance with the Article 10 of the Act on Special Measures Concerning Nuclear Emergency Preparedness. (13:09 March 13th)

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