Au Japon, l'opérateur de la centrale nucléaire endommagée Fukushima Dai-ichi a pour la première fois autorisé des représentants des médias à pénétrer ce samedi dans le bâtiment d'un des réacteurs.
Pour limiter l'exposition aux radiations et gérer la sécurité, quatre journalistes et cameramen ont été choisis parmi les représentants des médias accompagnant le ministre en charge de la crise nucléaire Goshi Hosono. Les quatre sont entrés dans le bâtiment du réacteur 4 pour une observation qui a duré environ 30 minutes.
Au premier étage, le taux de radiation enregistré était de 500 microsieverts par heure au moment de la visite. Ce niveau de radiation entraîne une exposition à 1 millisievert après deux heures, soit le niveau annuel autorisé pour une personne.
Le bâtiment du réacteur a été fortement endommagé par une explosion d'hydrogène le 15 mars de l'année dernière, quatre jours après que la centrale eut été touchée par le tsunami déclenché par un puissant séisme.
Aucune fusion ne s'est produite dans le réacteur parce qu'il était provisoirement à l'arrêt pour une inspection de routine et le combustible nucléaire avait été transporté vers une piscine de stockage. La piscine contient 1535 barres de combustible et Tepco envisage d'y poser un couvercle dans le cadre des préparatifs en vue du début de l'enlèvement des barres l'an prochain.
Japan's nuclear safety agency is set to ask the operators of 4 nuclear power plants to re-examine the effects of seismic activities that it says became more active after the March 2011 earthquake in northern Japan.
The Nuclear and Industrial Safety Agency will request the reassessment of quake resistance for the Tomari plant in Hokkaido, Tsuruga and Monju plants in Fukui Prefecture and the Shimane plant in Shimane.
It says the risk has increased of active faults more than 5 kilometers away from each other shifting simultaneously and causing a greater earthquake than predicted.
Hokkaido Electric Power Company says even if the 2 active faults on the sea and the land move at the same time, the assumed temblor in part of the Tomari facility will be a little larger than that previously calculated. It says quake resistance can be secured as important buildings are little affected by the quake.
But experts at the agency pointed out at a meeting that the tremor will be further intensified if the 2 active faults shift simultaneously.
They asked the company to reassess quake resistance based on the new assumption.
The company says it will respond appropriately in line with the experts' views, but it insisted that there will be no problem with the ability of key equipment to safeguard the nuclear plant.
Results of the reassessment could force a revision of quake resistance standards at the plants.
They could also affect the outcome of the stress tests required for restarting the idled plants.
The power companies say they will submit reports on their reassessments.
The Nuclear and Industrial Safety Agency will request the reassessment of quake resistance for the Tomari plant in Hokkaido, Tsuruga and Monju plants in Fukui Prefecture and the Shimane plant in Shimane.
It says the risk has increased of active faults more than 5 kilometers away from each other shifting simultaneously and causing a greater earthquake than predicted.
Hokkaido Electric Power Company says even if the 2 active faults on the sea and the land move at the same time, the assumed temblor in part of the Tomari facility will be a little larger than that previously calculated. It says quake resistance can be secured as important buildings are little affected by the quake.
But experts at the agency pointed out at a meeting that the tremor will be further intensified if the 2 active faults shift simultaneously.
They asked the company to reassess quake resistance based on the new assumption.
The company says it will respond appropriately in line with the experts' views, but it insisted that there will be no problem with the ability of key equipment to safeguard the nuclear plant.
Results of the reassessment could force a revision of quake resistance standards at the plants.
They could also affect the outcome of the stress tests required for restarting the idled plants.
The power companies say they will submit reports on their reassessments.
Tuesday, April 24, 2012 06:57 +0900 (JST)











