Scientific American: Chernobyl ahora

Contaminantes radioactivos vida "útil" en la atmósfera:
Iodine-131 decae rapidamente en unos 3 meses
cesio-137 y estroncio 90, ambos tienen aproximadamente 30 años de vida media,
plutonio-239, uno de los principales isótopos en los reactores nucleares, tiene una media la vida de más de 24.000 años.

The worst nuclear plant accident in history: Live from Chernobyl

By Charles Choi | Mar 15, 2011 08:00 AM | 3
CHERNOBYL, Ukraine—The face mask and three radiation monitors I'm wearing here are grim reminders that I'm at the site of the worst nuclear accident in history. On April 26, 1986, 1:23:44 A.M. local time, explosions destroyed reactor No. 4 at the Chernobyl nuclear power plant, releasing approximately 400 times more radioactive fallout than the atomic bomb dropped on Hiroshima, according to the International Atomic Energy Agency.

Now, almost 25 years after the disaster, the Ukrainian government has officially opened the area up for tourism. But just how safe is the zone now?

Radiation
After the explosions, it was unclear how contaminated the surroundings were, so the authorities declared an arbitrary 30-kilometer distance from the reactor off-limits, and roughly 115,000 people were evacuated from the area. This "exclusion zone" is now open to tourism.

I drove to Chernobyl with health physicist Vadim Chumak at the Research Center for Radiation Medicine at the Academy of Medical Sciences of Ukraine and his colleagues. A car shuttles there every week to collect stool samples from workers to test for any plutonium they might have accidentally absorbed. (Science, like journalism, can be a dirty job, but someone has to do it.)

The world is normally bathed in a low level of radiation. In Kiev, where I started my trip, one normally receives 0.1 millionths of a sievert every hour. This is pretty much the level of radiation we saw on the road on the roughly two-hour, 150-kilometer drive into the exclusion zone, but readings on our dosimeter temporarily climb up to 4.76 millionths of a sievert per hour when our car passes through the old path of the radioactive plume from the destroyed reactor.

How safe this area is now after the accident depends on what radioactive material was released and where it went. There are four kinds of radionuclides or radioactive isotopes that are of special concern at the site. Iodine-131 is rapidly absorbed by the thyroid gland and increases the risk of childhood thyroid cancer. Cesium-137 mimics potassium inside the body, seeking out muscle. Strontium-90 acts like calcium, attracted to bone. Plutonium-239 and other isotopes can stay in the body indefinitely, irradiating organs.

These four materials escaped from the explosions to varying distances, given factors such as their mass and melting points. Iodine-131 and cesium-137 were both very broadly transported hundreds of kilometers, while strontium-90 remained in dust just 30 kilometers from the power plant and plutonium traveled only four kilometers or so.
Iodine-131 decays rapidly, and was virtually gone from the environment after only three months, Chumak says. However, cesium-137 and strontium-90 both have approximately 30-year half-lives, meaning they each take roughly three decades for half their material to decay, and plutonium-239, one the main isotopes in nuclear reactors, has a half-life of more than 24,000 years.

Chernobyl: Timeline of a Tragedy on Dipity.

After the disaster, both emergency workers dubbed "liquidators" and natural forces helped to reduce airborne levels of radiation. The liquidators sprayed detergents and latex-like binding solutions from helicopters and automobiles to bind contaminants. The roads were paved to cover radioactive dust, while ploughs flipped soil over to bury polluted soil. Meanwhile, rain helped contaminants migrate down into the ground.

The exclusion zone was possibly safe for tourism "about five years after the accident," Chumak says. Still, just because one can tour the area does not mean everywhere here is safe to tread. There are hot spots that remain highly contaminated, especially in the path of the radioactive plume. Where tourists are allowed to go and how long they will be allowed to stay will be strictly controlled to keep their risks of exposure down.

And there are some places here that remain too dangerous for tourists to go, such as the sarcophagus.

Inside the sarcophagus
Soon after firefighters extinguished the blazes from the explosions at Chernobyl, workers quickly built a structure of steel and concrete technically known as the Shelter Object but commonly known as the sarcophagus to entomb the remains of the damaged reactor and keep any more contaminants from escaping. It remains one of the most radioactive areas in the zone.

Nowadays, workers here maintain the corroding sarcophagus, monitor the radioactive material inside, and decontaminate what they can. To enter the structure with them, I strip down to only my underwear in a "clean room" and walk in a hospital gown and slippers into a "hot room," where I put on the pure white outfit given to everyone on site—scrubs, a jacket, trousers, a scrub cap, socks, gloves and a mask with the highest-grade filter available for dust. On top of that I don an overcoat, a hardhat and crusty boots. In addition, I am carrying the radiation badge I had when I entered the 30-kilometer exclusion zone, a second radiation badge I was given when I entered the area of the plant, and a personal electronic dosimeter to tell me exactly how much radiation I am receiving.

(The workers don't normally wear lead shielding, and neither do I. Although lead can protect against radiation, it slows you down, thus increasing the dose you ultimately receive.)

The maximum dose of radiation that workers here are generally allowed on a daily shift is 0.1 thousandths of a sievert, the level of radiation one gets from a 90-minute transatlantic flight or from four hours watching a plasma screen television, says Vladimir Malyshev, chief safety officer at the Chernobyl nuclear power plant. When I am standing right in front of the sarcophagus, the readings leap up to 0.12 thousandths of a sievert per hour, or 1,200 times that seen in Kiev.

After passing an electronic checkpoint—one of a half-dozen or so that I stopped at—I find myself in the dark, gutted remains of the control room for reactor No. 4. Here engineers made the fateful errors that poisoned the Earth.

After returning from the sarcophagus, I leave everything I wore outside in a locker in the hot zone and take a mandatory shower to wash away any potential contamination. I don't think I've ever wanted to be clean more in my life.

Life and wildlife
Although Chernobyl might be safe for a day of tourism, living there is another question. The Ukrainian government did allow people who originally lived in the exclusion zone to resettle on an individual basis. For instance, some areas within 30 kilometers of the explosions are relatively clean, and the elderly would probably not absorb unhealthy levels of radiation in what time they had left, Chumak says.

However, some places remain too dangerous for resettlement. "People might be allowed to live in the 30-kilometer zone, but I don't expect anyone to live within the 10-kilometer zone, ever," Chumak says. "There's some plutonium there."

Officials there did say I should look out for wildlife in the zone. "A mad wolf attacked six people here recently," Malyshev says.

The disaster's impact on wildlife in the zone remains hotly contested. For instance, radiation biologist Ron Chesser at Texas Tech University in Lubbock and his colleagues suggest the area is thriving with life now that humans have left, finding that the wild boar population there has grown 10 to 15 times than what it was before the accident, and that other fauna are often seen in the area, such as wolves, rabbits, red deer, black storks and moose. Their genetic work suggests that any effects of radiation are subtle enough to not lead to any mutations passed down across generations, with the animals perhaps acclimatizing to any damage by boosting their genetic repair mechanisms. As bad as the radiation is, the effects of humans on the environment might have been worse, Chesser concludes.

On the other hand, biologist Tim Mousseau at the University of South Carolina at Columbia and his colleagues have found that species richness of forest birds was reduced by more than half when comparing sites with normal background levels of radiation to sites with the highest levels in the exclusion zone, and the numbers of bumblebees, grasshoppers, butter ies, dragonflies and spiders decreased too. Analysis of more than 7,700 barn swallows in Chernobyl and other areas in Ukraine and Europe suggested ones from in or near the exclusion zone had higher levels of abnormalities such as deformed toes, beaks and eyes or aberrant coloration, and recent work also suggests that birds living in areas with high levels of radiation around Chernobyl have smaller brains.

Both teams stand by their own work and suggest the other made errors related to geographic variability.

Tourist attraction?
So what can tourists see at Chernobyl? One can often see and feed giant catfish in the 22-square-kilometer nuclear power plant cooling pond, although during cold weather, the pond is frozen over and covered in snow. In the distance, one can also see a giant radar grid roughly 150 meters high—taller than the Great Pyramid of Giza's current height—once meant to track any nuclear missiles launched from the United States. "It needed a lot of power, which is why it was near Chernobyl," Chumak explains.

The city of Pripyat, abandoned after the accident, is frozen in time, with the Communist hammer and sickle still adorning streetlights here. Nature is reclaiming the area, with white birch and green pines hiding many of the blocky Soviet buildings and animal tracks fresh on the snow still covering the ground here in the first week of March.

By a dock near a riverside cafe in Pripyat, the scientists I traveled with started gathering pussy willows, completely unbidden. These flowers bloom under the snow, and the men want to bring them back for International Women's Day on March 8. "These mean spring," says physicist Vitalii Volosky at the Research Center for Radiation Medicine in Kiev.

Despite the official announcement, tourism to Chernobyl is nothing new—trips have been going there for about a decade. The recent publicity regarding tourism may have its roots in the economic impact of Chernobyl—even two decades after the disaster, roughly 6 percent of the national budgets of both Ukraine and Belarus were still devoted to Chernobyl-related benefits and programs, according to a 2005 report from the Chernobyl Forum, comprised of eight United Nations agencies and the governments of Ukraine, Belarus and Russia. "There is this motivation there to do what can be done to return some of this land to productive use," Mousseau says.

Among those who lived through the disaster, the idea of tourism to Chernobyl brings up strong emotions, just as it might for New Yorkers dealing with 9/11. "If we are wise, we will make Chernobyl a museum for humankind just like Hiroshima and Nagasaki," Chumak says.

Among the younger generation in Kiev, there is real interest in visiting. "My son really wants to go, as do a couple of young students here," Chumak says.

Still, for others, tourism to Chernobyl holds no attraction. "Personally, every trip I make there is not a positive one," says physicist Elena Bakhanova at the Research Center for Radiation Medicine in Kiev. "It was a human error, a sign of human foolishness."
Images: Charles Q. Choi in the control room for destroyed reactor No. 4 at the Chernobyl nuclear power plant; Health physicist Vadim Chumak at the Research Center for Radiation Medicine at the Academy of Medical Sciences of Ukraine in Kiev. He is wearing a respirator mask with the highest-grade filter available against aerosols, to protect against airborne contamination; The entrance to a "hot room" at the facility where workers at Chernobyl change their clothing. In the "clean room," I took off all my clothing except my underwear. In the hot room, I was given clothing to wear in the sarcophagus; Visitor's badge and radiation badge. The visitor's badge has a microchip scannable at electronic checkpoints. The radiation badge is a dosimeter that measures my exposure to radiation—the silver disk on the badge measures the radiation my skin received, while the black bump measured the levels deeper tissues experienced; This giant radar grid relatively close to the Chernobyl nuclear power plant was once meant to track any nuclear missiles launched from the United States. It is roughly 150 meters high, taller than the Great Pyramid of Giza's current height. Credit for all images: Charles Q. Choi.
About the Author: Charles Q. Choi (@cqchoi) is a frequent contributor to Scientific American. His work has also appeared in The New York Times, Science, Nature and Wired, among others. In his spare time, he has traveled to all seven continents. This post is the first in a series of stories from Chernobyl that Choi has written for Scientific American.
The views expressed are those of the author and are not necessarily those of Scientific American.


http://www.scientificamerican.com/blog/post.cfm?id=the-worst-nuclear-plant-accident-in-2011-03-14

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Alemania y Suiza se replantean su futuro nuclear debido al tsunami de Japón La c

Alemania y Suiza se replantean su futuro nuclear debido al tsunami de Japón

La confederación helvética suspende los procedimientos para autorizar nuevas centrales y Alemania podría no prolongar su vida

ABC

Día 14/03/2011 - 14.20h

COMENTARIOS

EFE

Mapa de las nucleares niponas

Suiza ha suspendido todos los procedimientos en curso para autorizar nuevas centrales nucleares mientras se examina la seguridad de las ya existentes en el país, según anunció hoy la ministra de Energía, Doris Leuthard. La medida fue adoptada en respuesta a la grave alarma nuclear creada en Japón tras el terremoto del pasado 11 de marzo y el accidente en la central de Fukushima. El Ministerio de Energía señaló que Leuthard ha ordenado «volver a examinar la seguridad de las centrales existentes», informa Efe.

La Inspección federal de la Seguridad Nuclear analizará las causas exactas del accidente nuclear en Japón, y de ahí podría decidirse la revisión de las normas actualmente en vigor en Suiza, señaló el Ministerio.

También en Alemania

La decisión del Gobierno alemán de ampliar la vida de las centrales nucleares del país podría quedar suspendida, según ha afirmado este lunes el ministro de Asuntos Exteriores, Guido Westerwelle, después de la crisis nuclear que se ha producido en Japón a raíz de los daños provocados por el terremoto y el posterior tsunami del viernes pasado, informa Reuters.

La canciller alemana, Angela Merkel, ha sido criticada por la decisión del Ejecutivo de prorrogar la vida de las viejas plantas atómicas alemanas, una medida sumamente impopular entre los ciudadanos. Westerwelle, que lidera el Partido Democrático Liberal, miembro de la coalición gobernante, ha respondido a una pregunta de un periodista sobre si esa decisión que se tomó el año pasado podría quedar suspendida temporalmente diciendo "Me imagino que sí".

El tsunami japonés ha puesto en duda la seguridad de las centrales nucleares

Previamente, el comisario europeo de Energía, Guenther Oettinger, había dicho que se debe comprobar rigurosamente la seguridad en las centrales más antiguas y no descartó cerrar algunas en caso de que fuese necesario. El ministro de Medio Ambiente, Norbert Roettgen, ha pedido una nueva evaluación de riesgos en las plantas nucleares y ha señalado que su partido y el de Merkel, la Unión Cristiano Demócrata (CDU), deberían reabrir el debate sobre la energía atómica. Oettinger fue primer ministro del estado suroccidental de Baden-Wuerttemberg, donde la CDU podría perder el poder en las elecciones que se celebrarán dentro de dos semanas, en parte debido a que los Verdes, que se oponen a la energía nuclear, tienen cada vez más apoyo entre el electorado.

Consecuencias políticas y econ{omicas de la crisis nuclear

03/14/2011 01:52 PM

The World From Berlin
Nuclear Disaster 'Will Have Political Impact as Great as 9/11'

The nuclear disaster in Fukushima makes it hard to ignore the vulnurabilities of the technology. It could spell the end of nuclear power, German commentators argue on Monday. The government in Berlin may now cave in to mounting pressure to suspend its 12-year extension of reactor lifetimes, they say.

The nuclear accident at Japan's Fukushima plant following Friday's earthquake and tsunami has led to anxious questions in Germany about the safety of its own nuclear reactors and is putting the government under intense pressure to rethink its decision to extend plant lifetimes by an average of 12 years.

German media commentators across the political spectrum are saying the accident in a highly developed nation such as Japan is further evidence that nuclear power isn't safe. One commentator in the conservative Die Welt went as far as to liken the global impact of the Fukushima explosions to that of the 9/11 terrorist attacks.

Chancellor Angela Merkel's coalition of conservatives and the pro-business Free Democratic Party (FDP) reversed the planned phaseout of the 17 nuclear reactors by 2021, amending a decision taken by a previous center-left government in 2002 to end nuclear power generation in Germany.

She argued that nuclear power was needed as "bridge technology" to ensure the supply of affordable power as Germany converts to renewable energy generation. She plans to increase the share of renewable generation to 80 percent by 2050, from a current level of only 16 percent.

A majority of Germans are opposed to nuclear power and the Fukushima accident is becoming a campaign issue ahead of state elections, the most important of which is being held in the conservative-ruled and wealthy state of Baden-Württemberg on March 27. Merkel's Christian Democratic Union (CDU) party has held the state since 1953, and a defeat would be a major psychological blow to the chancellor and her party.

It would also make it harder for her to pass legislation because the opposition parties would gain power in the country's upper legislative chamber, the Bundesrat, which represents the interests of the states and has the right of co-determination on many important laws.

On Monday, support in Merkel's coalition for extending nuclear lifetimes started to crumble. Foreign Minister Guido Westerwelle, the leader of the FDP, called for a safety review at all German nuclear plants. Power stations whose cooling systems were found to lack multiple safety levels would have to be switched off "until the situation is totally clear."

Other members of the coalition have also been calling for a rethink.

German media commentators say Fukushima may force Merkel to shut German reactors down sooner.

Center-left Süddeutsche Zeitung writes:

"The events in Japan, which geographically couldn't be much further from Germany, will influence politics in this country. They could soon start changing majorities and make governing even harder for the center-right coalition. The decision it made on nuclear power in September 2010 could be its undoing."

"There are few issues that can fire up people's emotions and mobilize them politically as much as nuclear power can. That's not good news for a government that supports nuclear power. Especially ahead of important regional elections, which won't affect the balance of power in national politics but which could well influence the morale of party workers to preserve that power."

"It's not good news because in the end, for example in Baden-Württemberg, it will only take a few percentage points more or less to determine the election outcome. Doubts among the supporters of the conservatives or the FDP could keep a few thousand voters from the ballot boxes -- or drive them into the arms of the center-left parties."

"For Merkel, it is hard to imagine a greater accident at present than the loss of a CDU governor in Baden-Württemberg."

"The safety precautions (at the Japanese nuclear plant) weren't just insufficient; the operating company TEPCO systematically breached them, as the government ascertained in 2002. TEPCO falsified security reports in more than 200 cases."

"Japan is a democracy, but so far the control of the government by the voters has hardly worked. Things only got a little better after the Democratic Party came to power two years ago. Before that, the often incompetent and corrupt governments were never voted out of office. The perestroika that Japan so urgently needs has scarcely begun."

"The unpopular government of Prime Minister Naoto Kan has been on the brink of collapse in recent weeks. It seemed paralyzed, distracted, disoriented and divided. Now it has to lead the country through what may be its worst disaster since 1945. Can it? In the Soviet Union the Chernobyl disaster accelerated the downfall of a broken, paralyzed political system."

Left-wing Die Tageszeitung writes:

"It was always said that danger only came from rickety old reactors in former Eastern Bloc states -- while conveniently ignoring that Sweden, France or the United States kept on narrowly avoiding maximum credible accidents. The disaster of Fukushima has made clear: There are situations in which even triple safety systems fail."

"The weak argument offered by the nuclear lobby that Germany isn't prone to heavy earthquakes and tsunamis doesn't apply. If a chain of serious events and stupid coincidences cause prolonged power outages, if the access routes are blocked or if the control room is destroyed by a plane crash, German reactors too will overheat. "

Conservative Die Welt writes:

"The earthquake of March 11 was no terrorist attack. But its political and psychological consequences will be as great as 9/11 because it has shown what a terrorist attack on nuclear plants would look like."

"The photos of burning buildings being swept away are disturbing enough, but nuclear power makes the decisive difference. The shockwave that went out from Fukushima may have only reached three kilometers in physical terms. But in mental terms it went around the whole world."

"Chernobyl was a special case. Nuclear energy was viewed with suspicion but it was accepted as long as modern democracies harnessed it with security precautions."

"That is over now. Faith in redundant, coincidence-proof security precautions has been wiped out by Fukushima. The high-tech democracy Japan has shown what could happen if an Internet attack on German or French nuclear reactors were to happen as it did with the 'Stuxnet' program against the Iranian nuclear program. Or if a determined, technologically skilled terrorist group were to seize control of a power station. One knew it before. Seeing it has made the difference."

Conservative Frankfurter Allgemeine Zeitung writes:

"It seems inappropriate to criticize the information policy of the Japanese government. Some of its statements may seem a bit overly reticent, but one should allow a government the right not to descend into speculation about all the theoretically possible scenarios. People are already being inundated by enough of such speculation."

"Japan has always been at the forefront of disaster relief efforts in other parts of the world. That is why the country now has at least a moral claim to assistance from its friends. People abroad may find it irritating that the country will probably have to keep on using nuclear power in the future. But this isn't the time for know-it-all advice. One should imagine what would have happened if a reactor in a country with less rigid safety standards had been subjected to such an earthquake."

The mass-circulation Bild tabloid writes:

"The nuclear accident is giving even firm supporters of nuclear power cause for thought, because the unthinkable happened in Fukushima. But even if we wanted to, we couldn't switch off all nuclear reactors overnight. Because the lights would literally go out. The maximum credible accident of Fukushima forces us to check the safety standards of our nuclear power stations. And to think harder about the quickest possible way to get out of nuclear power generation."

"The Japanese tragedy will dramatically change the debate over nuclear power. But the issue is too serious to start fanning people's fears in election campaigns. It may be tempting for campaigners to go out hunting for votes with the suffering of the Japanese. But that would be shabby, pitiful and repellent."

Left-wing Berliner Zeitung writes:

"This hasn't hit a run-down Soviet reactor, a badly constructed Russian plutonium machine which supplied the army with material for their nuclear weapons, as was the case with Chernobyl in 1986. Then and ever since, the builders of nuclear power stations in Europe, North America and Japan boasted that a serious accident could be virtually ruled out thanks to superior Western nuclear technology."

"Every country -- Germany, the US and Japan -- claimed to have the world's best reactors. Everything was secured several times over, all conceivable problems could be handled, all eventualities were prepared for, they said."

"The disaster at Fushima shows: It's simply not true."

"It is unlikely to be a coincidence that it was an old reactor with a design from the 1960s that got into trouble. The technology of this type of plant, which also operates in Germany, is outdated. Its safety level is significantly below that of modern nuclear plants, they wouldn't get construction approval these days. The accident has reinforced the lessons to be drawn from this: The plants that were originally intended for a lifespan of 40 years must not have their lifetimes extended, as is being done everywhere both in the West and the East -- because it yields major profits for the operators."

"On the contrary: the old reactors in particular must be taken off the grid as soon as possible. Germany realized that more than a decade ago, when the center-left government negotiated the nuclear phaseout with the power companies. For the center-right risk prolongers in Berlin, Fukushima is the writing on the wall, whether they're ready to realize that or not."

"The radioactive fallout from Fukushima won't hit Germany, but the political fallout has already arrived. People are alarmed and there is major uncertainty about 'peaceful' nuclear power, not just among diehard anti-nuclear campaigners."

-- David Crossland

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