_vb_

На японской атомной электростанции "Фукусима-1" горит хранилище отработанного топлива. Об этом сообщает Международное агентство по атомной энергии (МАГАТЭ) со ссылкой на заявление властей Японии.

По информации МАГАТЭ, радиоактивный материал выбрасывается напрямую в атмосферу. Радиационный фон в районе хранилища достигает 400 миллизивертов в час, что почти в 1000 раз превышает предельно допустимые значения (500 микрозивертов в час).

Я немного попорчу оптимизм. Насчет "реакторы целехоньки": вот прямо сейчас смотрел очередной релиз по NHK. Со схемой. На схеме в нижней части реактора изображен suppression pool (не будем разливаться соловьем, что это такое). Так вот, сказано, что он поврежден, и из него происходит утечка в землю. Т.е. более целостность containment vessel больше не подтверждается. Эт раз.
Возникла новая проблема - в связи со взрывом уже 4-го реактора. Там рядом pool отработанных топливных сборок. Которые, оказывается (!), тоже надо охлаждать. Их система охлаждения тоже разрушена. Так вот, во время взрыва водорода они загорелись, т.е. началось, чего именно и боялись - пожар топливных сборок с массированным выбросом радионуклидов. Я думаю, что тот факт, что загорелись сборки не в самом реакторе, а пуле отработанных сборок, мало кого утешит. Те же куриные продукты,только в профиль. Судя по последним сообщениям, пожар потушили (но говорят это очень неуверенно), но проблема охлаждения этих сборок не решена.
И еще добавка по ночному взрыву реактора №2. Была произнесена фраза, каждое слово в отдельности я понимаю, а все вместе - увы. Сказано было, что предохранительный клапан как-то закрылся (сам собой?!), и его некоторое время безуспешно пытались открыть, попытки продолжались вплоть до взрыва. Это уже какой-то сюр чесслово.

Socionics:
если рванут реакторы, то жить будет невозможно практически на всей территории Японии.

Socionics:
И какой толк от этого защитного кожуха, если он сейчас испортится в связи с проблемой охлаждения.

Socionics:

Чернобыль взорвался при включенном реакторе или выключенном?

Vigar:
Взрыв - разлетелось. А осело

Vigar:
и горит - коптит

Vigar:
уверяют, что подобного точно не будет

Vigar:
Хотя кто знает как на самом деле там.

grafomanka:
что предлагаете-то?

webcat:
А это правда, что если отключить реактор, то стержни всё равно много лет остывают?

После остановки реактора даже в отсутствие цепной реакции тепловыделение продолжается за счет радиоактивного распада накопленных актиноидов и других продуктов деления. Выделяемая после остановки мощность зависит от количества накопленных продуктов деления
...
Таким образом, в первые секунды после останова остаточное энерговыделение составит примерно 6,5% от уровня мощности до останова. Через час — примерно 4,8%, через сутки — 1,5%, через год — 0,08 %. По этой причине существует необходимость при любых условиях обеспечить теплоотвод от реактора.

Military Crew Said to Be Exposed to Radiation, but Officials Call Risk in U.S. SlightBy WILLIAM J. BROAD
Published: March 13, 2011

The Pentagon was expected to announce that the aircraft carrier Ronald Reagan, which is sailing in the Pacific, passed through a radioactive cloud from stricken nuclear reactors in Japan, causing crew members on deck to receive a month’s worth of radiation in about an hour, government officials said Sunday.

The officials added that American helicopters flying missions about 60 miles north of the damaged reactors became coated with particulate radiation that had to be washed off.

There was no indication that any of the military personnel had experienced ill effects from the exposure. (Everyone is exposed to a small amount of natural background radiation.)

But the episodes showed that the prevailing winds were picking up radioactive material from crippled reactors in northeastern Japan. Ever since an earthquake struck Japan on Friday, the authorities worldwide have been laying plans to map where radioactive plumes might blow and determine what, if any, danger they could pose to people.

Blogs were churning with alarm. But officials insisted that unless the quake-damaged nuclear plants deteriorated into full meltdown, any radiation that reached the United States would be too weak to do any harm.

Washington had “hypothetical plots” for worst-case plume dispersal within hours of the start of the crisis, a senior official said Sunday. The aim, the official added, was “more to help Japan” than the United States, since few experts foresaw high levels of radiation reaching the West Coast.

For now, the prevailing winds over Japan were blowing eastward across the Pacific. If they continue to do so, international stations for radioactive tracking at Wake or Midway Islands might detect radiation later this week, said Annika Thunborg, a spokeswoman for an arm of the United Nations in Vienna that monitors the planet for spikes in radioactivity.

“At this point, we have not picked up anything” in detectors midway between Japan and Hawaii, Ms. Thunborg said in an interview on Sunday. “We’re talking a couple of days — nothing before Tuesday — in terms of picking something up.”

Agencies involved in the tracking efforts include the World Meteorological Organization, the International Atomic Energy Agency and the Comprehensive Test Ban Treaty Organization, which runs a global network of more than 60 stations that sniff the air for radiation spikes.

In the United States, the Departments of Defense and Energy maintain large facilities and cadres of specialists for tracking airborne releases of radiation, both civilian and military.

On Sunday, the Nuclear Regulatory Commission said it expected no “harmful levels of radioactivity” to move on the winds to Hawaii, Alaska or the West Coast from the reactors in Japan, “given the thousands of miles between the two countries.”

In interviews, some private nuclear experts called a windborne threat unlikely. Others urged caution.

“We’re all worrying about it,” said Robert Alvarez, a nuclear expert who, from 1993 to 1999, was a policy adviser to the secretary of energy, who runs the nation’s nuclear complex.

“It’s going to be very important,” he added, “for the Japanese and U.S. authorities to inform the public about the nature of the plumes and any need for precautionary measures.”

The plume issue has arisen before. In 1986, radiation spewing from the Chernobyl disaster in Ukraine was spread around the globe on winds and reached the West Coast in 10 days. It was judged more of a curiosity than a threat.

Since then, scientists have refined their abilities to monitor such atmospheric releases. The advances are rooted in the development of new networks of radiation detectors, flotillas of imaging satellites and the advent of supercomputers that can model the subtle complexities of the wind to draw up advanced forecasts.

With the Japanese crisis, popular apprehension has also soared.

“Concern has been raised about a massive radioactive cloud escaping and sweeping over the West Coast,” said a recent blog, recommending whole grains and health foods for fighting radiation poisoning.

On another blog, someone asked, “Should I take iodine now?” That referred to pills that can prevent poisoning from the atmospheric release of iodine-131, a radioactive byproduct of nuclear plants that the Japanese authorities have identified as escaping into the atmosphere.

While federal officials expected little danger in the United States from Japanese plumes, they were taking no chances. On Sunday, Energy Department officials, speaking on the condition of anonymity, said the agency was working on three fronts.

One main player is the Lawrence Livermore National Laboratory in California. Officials said they had activated its National Atmospheric Release Advisory Center, which draws on meteorologists, nuclear scientists and computer scientists to forecast plume dispersal.

Separately, energy officials said the agency was readying plans to deploy two-person monitoring and sampling teams, if necessary. The teams would travel to consulates, military installations and Navy ships to sample the air in a coordinated effort to improve plume tracking.

Finally, the department was preparing what it calls its Aerial Measuring System. Its detectors and analytical equipment can be mounted on a variety of aircraft. Officials said the equipment and monitoring team are staged out of the department’s Remote Sensing Laboratory at Nellis Air Force Base in Nevada, and are on two-hour call.

“We’re on top of this,” a department official said.

David E. Sanger contributed reporting from Washington