Friday, July 6, 2012

Nuclear Energy

Updated: July 5, 2012 New York Times
Before the earthquake and tsunami that hit northern Japan in March 2011, nuclear energy had been making something of a comeback. Concerns about global warming had led a range of environmentalists to set aside their concerns and join in pushing for the revival of an industry whose growth had stalled after the Three Mile Island accident in 1979 and the Chernobyl disaster in 1986. That was all changed by the Fukushima Daiichi Nuclear Power Station, whose three active generators suffered meltdowns.
A series of explosions and fires led to the release of radioactive gases. Radioactive materials were detected in tap water as far away as Tokyo, as well as in agricultural produce like vegetables, tea and beef.
The human and environmental consequences of the nuclear crisis could be dire and long-lasting. While the amount of radioactive materials released from Fukushima Daiichi so far has equaled about 10 percent of that released at Chernobyl, officials said that the radiation release from Fukushima could, in time, surpass levels seen in 1986.
In Japan, the disaster brought down one government and has shaken the nation’s trust in the tight alliance of government and business that has been at the core of economic policy for decades. Around the world, it gave new impetus to efforts to slow or roll back nuclear development, with Germany committing to shut all of its nuclear plants.
In December 2011, Prime Minister Yoshihiko Noda announced that technicians had regained control of reactors at Fukushima,declaring an end to the disaster. Mr. Noda said the government will now focus on removing the fuel stored at the site, opening up the ravaged reactors themselves and eventually dismantling the plant, a process that is expected to take at least four decades.
For many of the people of Fukushima, the crisis is far from over. More than 160,000 people remain displaced, and even as the government lifts evacuation orders for some communities, many are refusing to return home. And many experts still doubt the government’s assertion that the plant is now in a stable state — the equivalent of a “cold shutdown’' — and worry that officials are declaring victory only to quell public anger over the accident.
In early July 2012, a report released by an independent parliamentary commission concluded that the crisis was a preventable disaster rooted in government-industry collusion and the worst conformist conventions of Japanese culture. The report also warned that the plant may have been damaged by the earthquake in March 2011, even before the arrival of the tsunami — a worrying assertion as the quake-prone country is starting to bring its reactor fleet back online.
A Year Later, Grappling With Crucial Questions
A year after the disaster, Japan grapples with the question: Was the accident simply the result of an unforeseeable natural disaster or something that could have been prevented?
Japan’s nuclear regulators and the plant’s operator, Tokyo Electric Power, or Tepco, have said that the magnitude 9.0 earthquake and 45-foot tsunami were far larger than anything that scientists had predicted. That conclusion has allowed the company to argue that it is not responsible for the triple meltdown, which forced the evacuation of about 90,000 people.
But some insiders from Japan’s tightly knit nuclear industry have stepped forward to say that Tepco and regulators had for years ignored warnings of the possibility of a larger-than-expected tsunami in northeastern Japan, and thus failed to take adequate countermeasures, such as raising wave walls or placing backup generators on higher ground.
They attributed this to a culture of collusion in which powerful regulators and compliant academic experts looked the other way while the industry put a higher priority on promoting nuclear energy than protecting public safety. They call the Fukushima accident a wake-up call to Japan to break the cozy ties between government and industry that are a legacy of the nation’s rush to develop after World War II.
Tepco and its supporters say it is easy in hindsight to second-guess the company. They said no one could have been fully prepared for the magnitude 9.0 earthquake, the largest in Japan’s recorded history, and giant tsunami that knocked out cooling systems at three of Fukushima Daiichi’s six reactors.
But many experts and industry insiders disagree, saying the plant had ample warning, including from its own engineers.
A Vivid Account of the Crisis
In late February 2012, a report by Rebuild Japan Initiative Foundation, a private policy organization, offered one of the most vivid accounts yet of how Japan teetered on the edge of an even larger nuclear crisis than the one that engulfed the Fukushima Daiichi Nuclear Power Plant. A team of 30 university professors, lawyers and journalists spent more than six months on the inquiry into Japan’s response to the triple meltdown at the plant, which followed a massive earthquake and tsunami in March 11 that shut down the plant’s cooling systems.
The investigation found that in the darkest moments of the nuclear disaster, Japanese leaders did not know the actual extent of damage at the plant and secretly considered the possibility of evacuating Tokyo, even as they tried to play down the risks in public.
The team conducted interviews with more than 300 people, including top nuclear regulators and government officials, as well as Naoto Kan, who was prime minister during the crisis. They were granted extraordinary access, in part because of a strong public demand for greater accountability and because the organization’s founder, Yoichi Funabashi, a former editor in chief of the daily Asahi Shimbun, is one of Japan’s most respected public intellectuals.
The report describes how Japan’s response was hindered at times by a debilitating breakdown in trust between the major actors: Mr. Kan; the Tokyo headquarters of the plant’s operator, Tokyo Electric Power, known as Tepco; and Masao Yoshida, the manager at the stricken plant. The conflicts produced confused flows of sometimes contradictory information in the early days of the crisis, the report said.
It described frantic phone calls by the plant manager, Mr. Yoshida, to top officials in the Kan government arguing that he could get the plant under control if he could keep his staff in place, while at the same time ignoring orders from Tepco’s headquarters not to use sea water to cool the overheating reactors. By contrast, Mr. Funabashi said in an interview, Tepco’s president, Masataka Shimizu, was making competing calls to the prime minister’s office saying the company should evacuate all of its staff, a step that could have been catastrophic.
Doubts About a ‘Cold Shutdown’
The Japanese government declared in December 2011 that it hadfinally regained control of the overheating reactors at the Fukushima Daiichi plant. But even before it was made, the announcement faced serious doubts from experts.
A disaster-response task force headed by Prime Minister Yoshihiko Noda announced that the plant’s three damaged reactors had been put into the equivalent of a “cold shutdown,” a technical term normally used to describe intact reactors with fuel cores that are in a safe and stable condition. Some experts said that the announcement reflected the government’s effort to fulfill a pledge to restore the plant’s cooling system by year’s end, not the true situation.
Other experts expressed concern that the government would declare victory only to appease growing public anger over the accident, and that it could deflect attention from remaining threats to the reactors’ safety. One of those — a large aftershock to the magnitude 9 earthquake on March 11, which could knock out the jury-rigged new cooling system that the plant’s operator hastily built after the accident — is considered a strong possibility by many seismologists.
Plans to Decommission the Reactors
Soon after declaring that the reactors at the Fukushima Daiichi plant had been put into the equivalent of a “cold shutdown,” the Japanese government announced plans for fully shutting them down. Doing so will take 40 years and require the use of robots to remove melted fuel that appears to be stuck to the bottom of the reactors’ containment vessels, according to a detailed government plan.
Japan’s nuclear crisis minister, Goshi Hosono, acknowledged that no country has ever had to clean up three destroyed reactors at the same time. Mr. Hosono told reporters the decommissioning faced challenges that were not totally predictable, but “we must do it even though we may face difficulties along the way.”
According to the plan, the plant’s operator, Tokyo Electric Power, will spend two years removing spent fuel rods from storage pools located in the same buildings as the damaged reactors. At least one of those pools, which are highly radioactive, was exposed by hydrogen explosions that destroyed the reactor buildings in the first days of the accident.
The most technically challenging step will be removing the melted fuel, a process that the government said will take 25 years and require new types of robots and other new technologies that have not even been developed yet. After the removal, fully decommissioning the reactors will take another 5 to 10 years, according to the plan.
A Confused Cleanup Effort
Nobody really knows how to clean up after a nuclear accident. But in early 2012, the Japanese government was giving it a try,handing out an initial $13 billion in contracts meant to rehabilitate the more than 8,000-square-mile region most exposed to radioactive fallout — an area nearly as big as New Jersey.
The government’s main goal is to eventually enable the return of many of the 80,000 or more displaced people nearest the site of the nuclear disaster. It is far from clear, though, that the unproved cleanup methods will be effective.
Also disturbing to critics of the decontamination program is the fact that the government awarded the first contracts to three giant construction companies — corporations that have no more expertise in radiation cleanup than anyone else does, but that profited hugely from Japan’s previous embrace of nuclear power.
An Environment Ministry official said that big construction companies were best equipped to gather the necessary manpower, oversee large-scale projects like decontaminating highways and mountains, and properly protect and monitor radiation exposure among the cleanup workers.
But there is little consensus on what cleanup methods might prove effective in Japan. Radioactive particles are easily carried by wind and rain, and could recontaminate towns and cities even after a cleanup crew has passed through, experts say.
Nuclear Power: Overview
Nuclear power plants use the forces within the nucleus of an atom to generate electricity.
The first nuclear reactor was built by Enrico Fermi below the stands of Stagg Field in Chicago in 1942. The first commercial reactor went into operation in Shippingport, Pa., in December 1957.
In its early years, nuclear power seemed the wave of the future, a clean source of potentially limitless cheap electricity. But progress was slowed by the high, unpredictable cost of building plants, uneven growth in electric demand, the fluctuating cost of competing fuels like oil and safety concerns.
Accidents at the Three Mile Island plant in Pennsylvania in 1979 and at the Chernobyl reactor in the Soviet Union in 1986 cast a pall over the industry that was deepened by technical and economic problems. In the 1980s, utilities wasted tens of billions of dollars on reactors they couldn’t finish. In the ‘90s, companies scrapped several reactors because their operating costs were so high that it was cheaper to buy power elsewhere.
But in the early years of the 21st century, more than a dozen companies around the United States became eager to build new nuclear reactors. Growing electric demand, higher prices for coal and gas, a generous Congress and a public support for radical cuts in carbon dioxide emissions all combined to change the prospects for reactors, and many companies were ready to try again.
The old problems remain, however, like public fear of catastrophe, lack of a permanent waste solution and high construction costs. And some new problems have emerged: the credit crisis and the decline worldwide of factories that can make components. The competition in the electric market has also changed.
Most importantly, the disaster in Japan, with its wide impact and huge cleanup costs, has given both environmental groups and governments around the globe new reason for caution.
Nuclear Energy: How It Works
Nuclear power is essentially a very complicated way to boil water.
Nuclear fuel consists of an element – generally uranium – in which an atom has an unusually large nucleus. The nucleus is made up of particles called protons and neutrons. The power produced by a nuclear plant is unleashed when the nucleus of one of these atoms is hit by a neutron traveling at the right speed.
The most common reaction is that the nucleus splits — an event known as nuclear fission — and sets loose more neutrons. Those neutrons hit other nuclei and split them, too. At equilibrium — each nuclear fission producing one additional nuclear fission — the reactor undergoes a chain reaction that can last for months or even years.
When the split atom flings off neutrons, it also sends out fragments. Their energy is transferred to water that surrounds the nuclear core as heat. The fragments also give off sub-atomic particles or gamma rays that generate heat.
Depending on the plant’s design, the water is either boiled in the reactor vessel, or transfers its heat to a separate circuit of water that boils. The steam spins a turbine that turns a generator and makes electricity.
Sometimes instead of splitting, the nucleus absorbs the neutron fired at it, a reaction that turns the uranium into a different element, plutonium 239 (Pu-239). This reaction happens some of the time in all reactors. But in what are known as breeder reactors, neutrons fired at a higher force are absorbed far more often. In this process, spent uranium fuel can be recycled into Pu-239, which can be used as new fuel. But problems with safety and waste disposal have limited their use – a fuel recycling plant that operated near Buffalo for six years created waste that cost taxpayers $1 billion to clean up.
Discovery and the Birth of an Industry
The possibility of nuclear fission – splitting atoms — was recognized in the late 1930s. The first controlled chain reaction came in 1942 as part of the Manhattan Project, America’s wartime effort to build an atom bomb. That project entailed construction of several reactors, but for them, the energy was a waste product; the object was plutonium bomb fuel. On July 16, 1945, at the Trinity Site in New Mexico, the project’s scientists set off a chain reaction that was designed to multiply exponentially – the first blast of an atomic bomb.
Even before the war ended, the military was looking at reactors for another use, submarine propulsion. Work on those reactors began in the early 1950s, and on some other uses of nuclear power that never came to fruition, like nuclear-powered airplanes.
By general consensus, the first commercial reactor was a heavily subsidized plant at Shippingport, Pa. That was essentially a scaled-up version of a submarine reactor. In the United States and abroad, as the cold war and a vast nuclear arms race took shape, the race was on to find a peaceful use for the atom.
In December 1953, President Dwight D. Eisenhower delivered a speech at the United Nations called “Atoms for Peace,” calling for a “worldwide investigation into the most effective peace time uses of fissionable material.’’
Messianic language followed. Rear Admiral Lewis L. Strauss, chairman of the Atomic Energy Commission, told science writers in New York that “our children will enjoy in their homes electrical power too cheap to meter.’’
The “too cheap to meter” line has dogged the industry ever since. But after a slow start in the 1950s and early ’60s, larger and larger plants were built and formed the basis for a great wave of optimism among the electric utilities, which eventually ordered 250 reactors.
As it turned out, many of those companies were poor at managing massive, multiyear construction projects. They poured concrete before designs were complete, and later had to rip and replace some work. New federal requirements slowed progress, and delays added to staggering interest charges.
Costs got way out of hand. Half the plants were abandoned before completion. Some utilities faced bankruptcy. In all, 100 reactors ordered after 1973 were abandoned. By the time of the Three Mile Island accident, ordering a new plant was unthinkable and the question was how many would be abandoned before completion.
Safety – Three Mile Island and Chernobyl
The core meltdown at Three Mile Island 2, near Harrisburg, Pa., in March 1979, and the explosion and fire at Chernobyl 3 in April 1986, near Kiev, in the Ukraine, are events the industry cannot afford to repeat.
Three Mile Island unit 2 was the youngest reactor in the United States. The plant, like all others on line in the United States, had been built with impressive back-up systems to guard against a big pipe break that could leave the nuclear core without its blanket of water. But here a relatively slow leak combined with misunderstandings by the plant operators about their complex controls, factors that had not been anticipated.
The operators knew that they had a routine malfunction and had taken action to deal with it. But as problems mounted, in their windowless control room, filled with dials, warning lights and audible alarms that all clamored for attention faster than they could absorb it, they did not realze for hours that a valve they believed they had closed was actually stuck open. Rather than resolving the problem, they had allowed most of the cooling water to leak out.
Tens of thousands of worried residents evacuated the surrounding area. The reactor core was destroyed, but with little damage beyond it.
The reactor had shut itself down in the first few moments of the malfunction, when an automatic system triggered control rods to drop into the core, shutting off the flow of neutrons that sustained the chain reaction. And even if that had not happened, the reaction would have stopped as the cooling water boiled away, because the water acted as a moderator, slowing the neutrons down.
The plant leaked radioactive materials; post-accident estimates said the amount was very small. No one died, but in a matter of hours, a billion-dollar asset had become a billion-dollar liability.
In contrast, the Chernobyl reactor in the Ukraine was moderated by graphite, a material that does not boil away. And as graphite gets hotter, its performance as a moderator improves, meaning that the reaction speeds up. When a malfunction made the plan run hot, instead of shutting down, the reaction ran out of control and the reactor blew up.
Graphite has another unfavorable characteristic: it burns on contact with air. At Chernobyl, once the reactor exploded, hundreds of tons of graphite became the fuel for a fire that lasted at least three and a half hours, providing the energy to disburse the tons of radioactive material inside.
The government said 31 people died of radiation sickness in the following weeks. Estimates of the eventual number of dead are colored by politics, but a United National panel said in 2005 that the release of Iodine-131, a highly radioactive material that gets concentrated in the thyroid gland, would eventually cause 4,000 deaths. An “exclusion zone” 36 miles in diameter remains in place, and hundreds of thousands of people have been resettled.
Safety – Nuclear Waste
When the nucleus of a uranium atom is struck by a neutron, the atom breaks into fragments. Nearly all these fission products, few of which exist in nature, are unstable. They seek to return to stability by giving off an energy wave, called a gamma ray, or a particle, called alpha or beta radiation. Some transmute into a new, stable state in a matter of seconds; others remain radioactive for millennia.
Most fission products with very short half-lives – the length of time needed for half their atoms to be transmuted into something else — are intensely radioactive, which makes them a concern in the event of a leak. Other fission products, most of which are contained in spent reactor fuel, will remain radioactive for millions of years.
The Federal government always promised it would accept the high-level nuclear wastes, and beginning in the early 1980s, it signed contracts with the utilities, saying storage would begin in 1998. It hasn’t happened yet, and won’t before 2020, if then.
In the 1980s, the idea was to have the Energy Department study the geology of several sites and pick the best, but that job went very slowly, and Congress decided to make the choice itself. It chose Yucca Mountain, about 100 miles from Las Vegas, in large part because the site is extremely dry. But intensive study showed that what water does fall on the mountain runs through it far faster than scientists initially estimated.
In 2004, a federal appeals court threw out a set of federal rules for the site because they would only offer protection for 10,000 years, while scientists say the fuel would be hazardous for close to a million years.
President Obama declared that Yucca would not be used, but in June 2009 a federal judge ordered the Energy Department not to withdraw its application for an operating license, an application opposed by the state of Nevada and a range of private groups, some of whom hope the lack of a storage site will force the entire industry to shut down. The judge said Congress had required the department to file an application when it settled on the Yucca site.
California, Connecticut and other states have moved to block construction of new reactors until a repository is opened, but other states seem likely to go ahead.
In the meantime, at many plants the spent fuel is stored in casks that look like small silos, with a steel liner and a concrete shell. The fuel is put inside and dried, and the cask is filled with an inert gas to prevent rust. Then it is parked on a high-quality concrete pad, surrounded by floodlights and concertina wire, resembling a basketball court at a maximum-security prison.
Safety — Military Waste
The nation’s biggest plutonium problem is not from nuclear power but from nuclear weapons. The most troubling is Hanford, a 560-square-mile tract in south-central Washington that was taken over by the federal government as part of the Manhattan Project. (The bomb that destroyed Nagasaki in 1945 originated with plutonium made at Hanford.) By the time production stopped in the 1980s, Hanford had made most of the nation’s plutonium. Cleanup to protect future generations will be far more challenging than planners had assumed, according to an analysis by a former Energy Department official.
The plutonium does not pose a major radiation hazard now, largely because it is under “institutional controls” like guards, weapons and gates. But government scientists say that even in minute particles, plutonium can cause cancer, and because it takes 24,000 years to lose half its radioactivity, it is certain to last longer than the controls
The fear is that in a few hundred years, the plutonium could reach an underground area called the saturated zone, where water flows, and from there enter the Columbia River. Because the area is now arid, contaminants move extremely slowly, but over the millennia the climate is expected to change, experts say.
The finding on the extent of plutonium waste signals that the cleanup, still in its early stages, will be more complex, perhaps requiring technologies that do not yet exist. But more than 20 years after the Energy Department vowed to embark on a cleanup, it still has not “characterized,” or determined the exact nature of, the contaminated soil.
So far, the cleanup, which began in the 1990s, has involved moving some contaminated material near the banks of the Columbia to drier locations. (In fact, the Energy Department’s cleanup office is called the Office of River Protection.) The office has begun building a factory that would take the most highly radioactive liquids and sludges from decaying storage tanks and solidify them in glass.
That would not make them any less radioactive, but it would increase the likelihood that they stay put for the next few thousand years.
The problem of plutonium waste is not confined to Hanford. Plutonium waste is much more prevalent around nuclear weapons sites nationwide than the Energy Department’s official accounting indicates, said Robert Alvarez, who reanalyzed studies in 2010 conducted by the department in the last 15 years for Hanford; the Idaho National Engineering Laboratory; the Savannah River Site, near Aiken, S.C.; and elsewhere.
New Designs, New Issues
On the drawing boards at government labs are all kinds of exotic designs, using graphite and helium, or plutonium and molten sodium, and making hydrogen rather than electricity. But the experts generally agree that if a reactor is ordered soon, its design changes will be evolutionary, not revolutionary.
Many of the new designs have focused on the emergency core cooling systems, where the new goal is to minimize dependency on active systems, like pumps and valves, in favor of natural forces, like gravity and natural heat circulation and dissipation.
Westinghouse is one of the companies trying to market a reactor, the AP1000, with what is called a passive approach to safety. Compared to Westinghouse designs now in service, it requires only half as many safety-related valves, 83 percent less safety-related pipe and one-third fewer pumps.
A French company called Areva is building the EPR, for European Pressurized Water Reactor, which has four emergency core cooling systems, instead of the usual two. That not only makes it less likely that all systems would fail, but would allow the plant to keep running while one of the systems is down for maintenance.
The third entry is General Electric’s Economic Simplified Boiling Water Reactor, derived from its boiling water reactor design. It is tweaked for better natural circulation in case of an accident, so there will be less reliance on pumps. But three of its four potential customers have backed away.
The Nuclear Regulatory Commission is also considering a proposal that it give approval to a handful of standardized, completed designs, rather than approving each plant’s design individually after construction had begun. The hope is to cut a 10-year construction process in half.
Nuclear Power and Climate Change
Nuclear power has gained new adherents in recent years, including some environmentalists who had previously opposed it. The reason is growing concern over climate change, and the role of energy production in the build-up of carbon dioxide in the atmosphere. Nuclear plants do not burn fuel and so produce no carbon dioxide. Proponents of nuclear power say it is the only available method of producing large amounts of energy quickly enough to make a difference in the fate of the atmosphere.
In the 2008 presidential campaign, Senator John McCain, the Republican candidate, made expansion of nuclear power a central point of his agenda both for energy and global warming.
But expanding nuclear power to replace coal and oil would be a massive job, on a scale that some consider unrealistic. A study by the Princeton Carbon Management Initiative estimated that for nuclear to play a significant role in cutting emissions, the industry’s capacity would have to triple worldwide over the next 50 years — a rate of 20 new large reactors a year.
At the moment, though, industry leaders in the United States wonder whether the worldwide supplier base could support construction of more than four or five reactors simultaneously. Some reactors under construction, like a prototype EPR in Finland, are over budget and years behind schedule. All new projects have to depend on a single supplier for the biggest metal parts, Japan Steel Works.
And at the moment, the price of nuclear power seems too high. In Florida, Progress Energy wants to build two reactors with a total cost, including transmission and interest during construction, that translates into about $8,000 per kilowatt of capacity — the amount of power needed to run a single window air conditioner. On a large scale, it may be cheaper to build better air conditioners, some energy experts suspect.

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