Desastre nuclear de Fukushima/Japão Março 2011

Vince

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Os desenvolvimentos dos acidentes nucleares da central nuclear Fukushima I passam a ser acompanhados neste tópico, para notícias e discussões sobre o sismo e tsunami por favor usar ou outro

-> Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011


A situação do ponto de vista nuclear continua complicada, pelo que percebi, faltou a energia eléctrica necessária ao bombeamento de água que arrefece o reactor, e por azar os geradores de emergência foram afectados pela água do tsunami ficando inoperacionais, e agora estão a usar energia de uma 3ª fonte de emergência prevista, baterias, mas estas aguentam poucas horas.


The nuclear safety agency expanded the evacuation area after some radiation had also seeped outside the plant, the Associated Press also reported.

The cooling system for a reactor at the Fukushima Daiichi power plant was crippled after power was lost in the wake of a deadly earthquake and tsunami hit Japan on Friday afternoon.

The loss of electricity has also delayed the planned release of vapor from inside the reactor to ease pressure, AP said. Pressure inside one of the reactors had risen to 1.5 times the level considered normal.

Japanese authorities on Saturday were racing to find ways to deliver new backup generators or batteries to the plant.

The reactor, owned by Tokyo Electric Power Co., is drawing on battery power that may last only a few hours. Without electricity, the reactor will not be able to pump water to cool its hot reactor core, possibly leading to a meltdown or some other release of radioactive material.

Japanese authorities ordered the evacuation of about 3,000 residents within a 1.9-mile radius of the Fukushima Daiichi nuclear power plant and told people within a 16.2-mile radius to remain indoors, according to the Web site of the International Atomic Energy Agency's (IAEA) Incident and Emergency Centre.

The cooling problem affects the second of six reactors at the plant, on the east coast of Japan about 200 miles north of Tokyo and south of the heavily damaged town of Sendai.

Tokyo Electric had said it was going to vent gas from another unit to relieve pressure that had increased 50 percent in the reactor containment vessel. The company said on its Web site that the pressure increase was "assumed to be due to leakage of reactor coolant." It remained unclear where the leak was. The company said it did not think there was leakage of reactor coolant in the containment vessel "at this moment."

Altogether, 11 Japanese nuclear reactors shut down automatically, as they were designed to do in case of an earthquake. Japan has 55 nuclear plants and two under construction.

"There's a basic cooling system that requires power, which they don't have," said Glenn McCullough, former chairman of the Tennessee Valley Authority, referring to the unit in need of generators. McCullough, who has been keeping track of the situation in Japan, said that, after the tsunami, water had gotten into the diesel generators that would normally have provided backup power.


Continua:

http://www.washingtonpost.com/wp-dyn/content/article/2011/03/11/AR2011031103673.html
 

ecobcg

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

A situação com a central nuclear parece cada vez mais complicada:

Nuclear agency: Explosion at Japanese plant

http://edition.cnn.com/video/?/video/world/2011/03/12/bpr.grant.nuclear.plants.cnn

(CNN) -- An explosion sent white smoke rising above a nuclear plant where a massive earthquake and tsunami crippled cooling systems in northeastern Japan, the country's nuclear and industrial safety agency said.

Four workers were injured after the blast at the Fukushima Daiichi plant, the agency said. It was not immediately clear where the blast occurred inside the plant, or what caused it.

One expert said the explosion was "clearly a serious situation," but may not be related to problems inside the plant's nuclear reactor.

Other effects of the tsunami may have caused the blast, said Malcolm Grimston, associate fellow for energy, environment and development at London's Chatham House.

"It's clearly a serious situation, but that in itself does not necessarily mean major (nuclear) contamination," he said.

Japanese public broadcaster NHK said the injured workers were in the process of cooling a nuclear reactor at the plant by injecting water into its core.

Earlier Saturday Japan's nuclear agency said workers were continuing efforts to cool fuel rods at the plant after a small amount of radioactive material escaped into the air.

The agency said there was a strong possibility that the radioactive cesium monitors detected was caused by the melting of a fuel rod at the plant, adding that engineers were continuing to cool the fuel rods by pumping water around them.

A spokesman for Japan's Nuclear and Industrial Agency earlier said atomic material had seeped out of one of the five nuclear reactors at the Daiichi plant, located about 160 miles (260 kilometers) north of Tokyo.

Authorities evacuated people living 10 kilometers from the reactor after an earthquake and tsunami crippled cooling systems there, as well as at another Tokyo Electric Power Company nuclear plant in Japan's Fukushima prefecture.

"This is a situation that has the potential for a nuclear catastrophe. It's basically a race against time, because what has happened is that plant operators have not been able to cool down the core of at least two reactors," said Robert Alvarez, a senior scholar at the Institute for Policy Studies in Washington.

The evacuations notwithstanding, the nuclear safety agency asserted Saturday that the radiation at the plants did not pose an immediate threat to nearby residents' health, the Kyodo News Agency said.

The International Atomic Energy Agency said Friday on its website that the quake and tsunami knocked out a Daiichi reactor's off-site power source, which is used to cool down the radioactive material inside. Then, the tsunami waves disabled the backup source -- diesel generators -- and authorities were working to get these operating.

On Saturday Japanese nuclear authorities said the cooling system had also failed at three of the four reactors at the Fukushima Daini plant -- located in another town in northeaster Japan's Fukushima prefecture.

Janie Eudy told CNN that her 52-year-old husband, Joe, was working at the Daiichi plant and was injured by falling and shattering glass when the quake struck. As he and others were planning to evacuate, at their managers' orders, the tsunami waves struck and washed buildings from the nearby town past the plant.

"To me, it sounded like hell on earth," she said, adding her husband -- a native of Pineville, Louisiana -- ultimately escaped.

The power company reported Saturday that about 1 million households were without power, and that power shortages may occur due to damage at the company's facility.

"We kindly ask our customers to cooperate with us in reducing usage of power," the company said.
Fonte:CNN


Japan Quake: Nuclear Plant Meltdown Fears

A radiation leak has been triggered by an explosion at an earthquake-hit nuclear plant in Japan - amid fears a meltdown is under way.

News of the leak was confirmed by the Japanese government after the walls and roof at Fukushima Number 1 nuclear power plant were destroyed in the blast.

Plumes of white smoke were sent billowing into the sky and several workers at the station are thought to be injured.

An evacuation radius has been widened to 12 miles and residents of the region have been urged to stay indoors, turn off air conditioning units and not to drink tap water.

Radioactivity in the control room at the plant is 1,000 times the normal level - and eight times the normal level in the area immediately outside the site.
Fonte:Sky News


Habitantes recebem orientações após explosão na Central nuclear de Fukushima


Imagens da televisão japonesa mostram a explosão ocorrida na central nuclear de Fukushima, um dia depois do violento terramoto seguido de um tsunami que devastou a região nordeste do país. Segundo a fonte, os moradores dos arredores da central nuclear foram aconselhados a permanecer em casa, não beber água canalizada e proteger o rosto com máscaras ou toalhas molhadas.

A área circundante das instalações apresenta agora uma radioactividade 20 vezes superior às condições normais. Também circularam informações de que partes da instalação tinham desabado.

De acordo com a televisão pública NHK, vários empregados da central ficaram feridos na explosão que ocorreu às 16H00 locais por razões ainda desconhecidas.

Já anteriormente a agência Jiji tinha anunciado a elevada probabilidade de acontecer uma fusão no reactor número um de Fukushima.

Um porta-voz da empresa eléctrica Tokyo Electric Power (Tepco), titular da central, negou, no entanto, que tal fenómeno estivesse a acontecer e afirmou que a empresa estava a tentar fazer subir o nível de água para arrefecer o reactor. A Tepco também informou ter libertado vapor radioactivo para reduzir a pressão excessiva no reactor da central nuclear.

"Seguindo as instruções do governo, libertámos parte do vapor, que contém substâncias radioactivas", explicou à AFP um porta-voz da Tepco. "Acompanhamos a situação e até o momento não há problemas". A radioatividade registada na sala de controlo do reactor da central de Fukushima 1 chegou a atingir um nível mil vezes superior ao normal após problemas de refrigeração provocados pelo terramoto.

A agência de notícias Kyodo noticiou também que a radioactividade registada durante uma hora na central nuclear de Fukushima corresponde ao limite anual admissível.

Momentos antes da libertação do vapor radioactivo, as autoridades decretaram uma zona de isolamento de 10 km à volta de Fukushima 1, que está a afectar as mais de 45 mil pessoas que vivem na região.

Os últimos números

O violento terramoto seguido de um tsunami que devastou o nordeste do Japão fez, pelo menos, 703 mortos, segundo o balanço provisório da polícia.

No entanto, o principal assessor e porta-voz do primeiro-ministro Naoto Kan, Yukio Edano, afirmou que o governo acredita que mais de mil pessoas morreram na tragédia.

A todo o instante chegam informações de mais corpos localizados no cenário de destruição deixado pelas ondas gigantes que destruíram mais de 3 mil residências.

Para além dos mortos há 704 desaparecidos e 1.040 feridos.

Mais de 5 milhões de casas continuam sem energia e mais de um milhão sem água potável.

SAPO/AFP
http://noticias.sapo.pt/info/artigo/1136293.html
 

Snifa

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

centrals.png


Segundo a televisão pública NHK, que cita a Agência de Segurança Nuclear do Japão, a explosão ocorreu às 16 horas locais (7 horas em Portugal Continental) e há pelo menos 20 empregados da central que estão feridos.

A televisão afirma que as causas da explosão são ainda desconhecidas.

No entanto, um especialista nuclear afirmou, em declarações à NHK, que a explosão pode ter sido "intencional".

A televisão nipónica está a mostrar imagens de uma nuvem de fumo branco por cima da central nuclear e anunciou que o nível de radioactividade está 20 vezes superior ao normal.

Entretanto, o tecto e as paredes do edifício do reactor de Fukushima desmoronaram-se, refere ainda a NHK.

As autoridades estão a adoptar "todas as medidas para assegurar a segurança dos habitantes", afirmou o porta-voz do governo, Yukio Edano, durante uma conferência de Imprensa.

Segundo a agência Kyodo, a dose de radioactividade recebida por um indivíduo no local do sinistro corresponde à que uma pessoa pode absorver no máximo num ano para evitar pôr em perigo a sua saúde.

A televisão afirma que as causas da explosão são ainda desconhecidas.

No entanto, um especialista nuclear afirmou, em declarações à NHK, que a explosão pode ter sido "intencional".

A televisão nipónica está a mostrar imagens de uma nuvem de fumo branco por cima da central nuclear e anunciou que o nível de radioactividade está 20 vezes superior ao normal.

http://www.jn.pt/PaginaInicial/Mundo/Interior.aspx?content_id=1804451&page=1
 

Vince

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

Um vídeo da explosão:



51124900.gif
 
Editado por um moderador:

Vince

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

Um artigo que parece resumir bem o que se sabe até agora sobre esta crise nuclear. A explosão terá sido no edifício devido a pressão de vapor resultante do arrefecimento, e não no reactor, que está selado numa estrutura mais robusta/isolada. Mas aguardemos por mais informações.

Battle to stabilise earthquake reactors
12 March 2011
UPDATE 6: 10.15 am GMT


Attention is focused on the Fukushima Daiichi and Daini nuclear power plants as Japan struggles to cope in the aftermath of its worst earthquake in recorded history. An explosion has been seen at the site.


Three of Fukushima Daiichi's six reactors were in operation when yesterday's quake hit, at which point they shut down automatically and commenced removal of residual heat with the help of emergency diesel generators. These suddenly stopped about an hour later, and this has been put down to tsunami flooding by the International Atomic Energy Agency (IAEA).

The loss of the diesels led the plant owners Tokyo Electric Power Company (Tepco) to immediately notify the government of a technical emergency situation, which allows officials to take additional precautionary measures.

Even now, the primary focus of work at the site remains to connect enough portable power modules to fully replace the diesels and enable the full operation of cooling systems.

Pressure and releases

Without enough power for cooling systems, decay heat from the reactor cores of units 1, 2 and 3 has gradually reduced coolant water levels through evaporation. The consequent increase in pressure in the coolant circuit can be managed via pressure release valves. However, this leads to an increase in pressure within the reactor building containment. Tepco has said that the pressure within the containment of Fukushima Daiichi 1 has reached around 840 kPa, compared to reference levels of 400 kPa.

The company has decided to manage this "for those units that cannot confirm certain levels of water injection" by means of a controlled release of air and water vapour to the atmosphere. Because this water has been through the reactor core, this would inevitably mean a certain release of radiation. The IAEA said this would be filtered to retain radiation within the containment. Tepco has confirmed it was in the process of relieving pressure at unit 1 while preparing to do the same for units 2 and 3



Explosion

Television cameras trained on the plant caputured a dramatic explosion surrounding unit 1 at around 6pm. Amid a visible pressure release and a cloud of dust it was not possible to know the extent of the damage. The external building structure does not act as the containment, which is an airtight engineered boundary within. The status of the containment is not yet known.

Monitoring of Fukushima Daiichi 1 had previously shown an increase in radiation levels detected emerging from the plant via routes such as the exhaust stack and the discharge canal.

Over the last several hours evacuation orders for local residents have been incrementally increased and now cover people living within ten kilometres of the power plant.



Raised temperatures

Meanwhile at adjacent Fukushima Daini, where four reactors have been shut down safely since the earthquake hit, Tepco has notified government of another emergency status.

Unit 1's reactor core isolation cooling system had been operating normally, and this was later supplemented by a separate make-up water condensate system. However, the latter was lost at 5.32am local time when its suppression chamber reached 100ºC. This led Tepco to notify government of another technical emergency situation.

Tepco has announced it has decided to prepare for controlled releases to ease pressure in the containments of all four units at Fukushima Daini.

A three kilometre evacuation is in progress, with residents in a zone out to ten kilometres given notice of potential expansion.


Workers

A seriously injured worker was trapped within unit 1 in the crane operating console of the exhaust stack. Breathing and a pulse could not be confirmed, Tepco said as it considered a rescue. At unit 3 one worker is known to have received a radiation dose of 106 mSv.
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html
 

Vince

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

CNN

The explosion at Japan's Fukushima nuclear plant was not caused by the nuclear reactor but by "water vapor that was part of the cooling process," Chief Cabinet Secretary Yukio Edano said Saturday. He said no harmful gases had been emitted by the explosion.
http://news.blogs.cnn.com/2011/03/1...death-toll-rises-amid-widespread-destruction/


Guardian

A British nuclear expert, Professor Paddy Regan, offers this analysis of what happened at Fukushima.
Regan, professor of nuclear physics at the University of Surrey, said:

"It looks as if the coolant pumps had initially stopped working. They shut down automatically when the reactor shuts down, but there is a backup system running off a diesel generator - it looks as though that's the bit that failed.

"As a result there is no way of pumping heat out of the reactor, so it has to cool naturally. If the reactor gets too hot, in principle this means the fuel rods can melt - but it looks unlikely this has happened to any great extent in this case.

"To reduce the pressure, you would have to release some steam into the atmosphere from the system. In that steam, there will be small but measurable amounts of radioactive nitrogen - nitrogen 16 (produced when neutrons hit water). This remains radioactive for only about 5 seconds, after which it decays to natural oxygen.

"But if any of the fuel rods have been compromised, there would be evidence of a small amount of other radioisotopes in the atmosphere called fission fragments (radio-caesium and radio-iodine). The amount that you measure would tell you to what degree the fuel rods have been compromised. Scientists in Japan should be able to establish this very quickly using gamma ray spectroscopy as the isotopes have characteristic decay signatures. Current reports seem consistent with a small leak to relieve pressure.

"But we still need to establish the cause and exact location of the explosion, which is a separate issue. So far it looks like it's not the reactor core that's affected which would be good news."
http://www.guardian.co.uk/world/2011/mar/12/japan-earthquake-tsunami-aftermath-live#block-18
 

Knyght

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

:pray:
Espero que consigam controlar...
 

ct5iul

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

Sobreviventes do tsunami enfrentam a ameaça de uma catástrofe nuclear

Os sobreviventes do tsunami que varreu na sexta-feira o nordeste do Japão vêem-se confrontados este Sábado com uma nova ameaça mortal - o espectro da fusão de um reactor nuclear no centro da zona sinistrada.

O Japão preocupava-se com uma possível fusão do reactor n°1 da central de Fukushima, a 250 km a nordeste de Tóquio, onde houve problemas no sistema de arrefecimento; logo no início, o fogo chegou a tocar barras de combustível irradiado, seguindo-se, depois, uma explosão.

A 12 km de lá, o sistema de arrefecimento do reactor n°2 também foi danificado. O tsunami que se seguiu ao terramoto de magnitude 8,9 - o sétimo mais potente da história - devastou a cidade de Sendai, onde a polícia encontrou entre 200 e 300 corpos na praia.

Entre 300 e 400 outros corpos estavam no porto de Rikuzentakata, que ficou submerso.

Em toda a região, os sobreviventes, ajudados por milhares de soldados, procuravam as suas famílias e os seus amigos. "Há tanta gente morta", declarou um homem idoso à imprensa, por entre lágrimas: "Não tenho palavras para descrever tal situação", prosseguiu.

Uma estranha calma reinava na manhã deste Sábado no litoral devastado do Pacífico, no qual a onda gigante, de 10 metros, levou bairros inteiros juntamente com casas, carros e pessoas.

Outros sobreviventes estão em estado de choque, depois da tragédia que pode ter causado mais de 1.700 mortes e desaparecidos.
 

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Pedro

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

Acidente nuclear no Japão tem nota 4 em escala

"A agência de segurança nuclear do Japão deu ao acidente ocorrido na usina Dai-ichi, em Fukushima, provocado pelo terremoto que atingiu ontem o país, uma nota 4, numa escala de zero a 7, disse um representante do órgão. De acordo com a escala, o nível 4 indica um acidente "com consequências locais". O desastre ocorrido em 1986 em Chernobyl recebeu a nota máxima.

O acidente reanimou um debate antinuclear na Alemanha. Cerca de 60 mil pessoas participaram de uma manifestação contra esse tipo de energia no Estado de Baden-Wuertemberg, onde haverá eleições no próximo dia 27 e nas quais o partido da primeira-ministra do país, Angela Merkel, enfrenta disputa acirrada depois de décadas no poder.

O ministro de Meio Ambiente da Alemanha, Norbert Roettgen, disse a uma estação de rádio hoje que acredita que provavelmente um colapso tenha ocorrido na usina nuclear de Fukushima, mas afirmou que, por causa da grande distância e das condições climáticas, uma ameaça à Alemanha quase pode ser totalmente descartada. Autoridades do Japão, enquanto isso, prosseguiam com esforços para conter os danos.

O ministro de Relações Exteriores da Alemanha, Guido Westerwelle, emitiu um alerta de viagens para o nordeste do Japão, onde vivem cerca de 100 alemães. Ele e Merkel concederão nesta tarde uma entrevista coletiva sobre a situação japonesa depois de uma reunião de crise da qual o ministro de Meio Ambiente e o do Interior participaram. As informações são da Dow Jones."

in Estadão(Brasil)
 

Pedro

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re: Sismo 9.0 e Tsunami no Japão/Pacífico - 11 Março 2011

"Nível de radioatividade diminui após acidente nuclear, afirma governo japonês
Acidente foi avaliado no nível 4 numa escala que vai até 7

O governo do Japão informou à Agência Internacional de Energia Atômica das Nações Unidas que os níveis de radioatividade após o acidente na central de Fukushima 1 "diminuíram nas últimas horas". De acordo com a AIEA, autoridades japonesas informaram que a explosão ocorreu fora da área de conteção primária da planta.

— A empresa que opera a unidade, Tokyo Eletric Power, confirmou que integridade da área de contenção primária permanece intacta — afirma o comunicado.

O acidente ocorrido neste sábado em Fukushima, no nordeste do Japão, foi avaliado no nível 4 numa escala que vai até 7, segundo a Agência de Segurança Nuclear e Industrial do Japão."
:confused: