Japan's nuclear crisis took a turn for the worse Tuesday, after a new round of fires and explosions unleashed radiation at the Fukushima Daiichi Nuclear Power Station in Okuma. The country is still reeling from last week's horrific earthquake and tsunami — with more than 10,000 feared dead and bodies still washing up on beaches — but now a manmade disaster threatens to eclipse the natural one. "We are on the brink. We are now facing the worst-case scenario," a senior reactor engineer at Kyoto University tells the New York Times. "We can assume that the containment vessel at Reactor No. 2 is already breached. If there is heavy melting inside the reactor, large amounts of radiation will most definitely be released."
The situation has been deteriorating quickly in the days since the quake. The first explosion at Fukushima came Saturday, followed by another on Monday and a third on Tuesday. The most recent blast damaged the vessel holding the reactor's nuclear core, and within three hours, radiation levels at the plant measured 11,930 micro sieverts per hour — well beyond the annual exposure limit for humans. A fire also broke out at the previously unaffected Reactor No. 4, which had been inactive for months at the time of the quake. Officials say spent fuel rods were responsible, having grown too hot for the water in their containment pool.
Radiation levels eventually fell to less than 500 micro sieverts per hour — not a health risk, but still "much higher than normal," according to a government spokesman — but things are still far from under control. Tokyo Electric was forced to evacuate all but 50 workers at Fukushima for safety reasons, and Japanese Prime Minister Naoto Kan urged everyone within 12.5 miles to evacuate. Everyone within 19 miles, he added, should stay indoors with the air-conditioning turned off. "Please do not go outside. Please stay indoors. Please close windows and make your homes airtight," Chief Cabinet Secretary Yukio Edano told residents in the danger zone. "These are figures that potentially affect health. There is no mistake about that." Japan has established a no-fly zone covering a 19-mile radius around Fukushima, while southeasterly winds mercifully blew the plume of radioactivity out to sea (experts say there's little risk of it crossing the Pacific).
The Japanese nuclear crisis is having a ripple effect around the world, forcing other nuclear nations to re-evaluate their own commitment to splitting atoms for energy. The U.S. seems to merely be flinching, with leading lawmakers expressing little more than a willingness to pause and mull further safety precautions. Some other countries have had stronger reactions, though — German Chancellor Angela Merkel, for example, announced Tuesday that Germany will take seven of its 17 reactors offline for three months while rethinking its plans for nuclear expansion.
But as journalist Robert Bryce writes in the Daily Beast, this may all be a moot point — or at least relatively moot. America's much-hyped "nuclear revival," Bryce says, was overhyped: The public may have finally gotten over the anxiety that Three Mile Island and Chernobyl spurred decades ago, but it won't get over how expensive nuclear power is, especially when natural gas is so cheap. "How can you compete with natural gas when it's priced at less than $4?" asks a U.S. nuclear utility executive who requested anonymity, answering his own question with "you can't." Nuclear power plants are notorious for construction delays and cost overruns, and even the public support and federal funding doled out by the Obama administration hasn't been enough yet to fully kick-start the expected revival. As Bryce points out, even before the crisis in Japan, the U.S. was only likely to build four new reactors in the foreseeable future.
But it's not like the U.S. is a new member of the nuclear club — it generates more net electricity from nuclear fission than any other nation, totaling about 20 percent of the country's overall portfolio. That's more than double the domestic energy produced from wind, [skipwords]solar[/skipwords] and hydroelectric power combined, meaning the U.S. will partially rely on nuclear power for quite some time, regardless of how many new reactors are built. And with several existing nuclear plants — as well as academic and military reactors — located near geologic faults in the Western U.S., the situation in Japan is inevitably relevant to America, no matter how much politicians want to downplay it.
With so much attention being dedicated to nuclear fission, some scientists are still chasing the elusive dream of nuclear fusion — and according to two new studies published in the journal Physical Review Letters, that may not be as delusional as critics often allege. Physicists have still never been able to produce nuclear fusion on a large commercial scale, but scientists working at the National Ignition Facility in Livermore, Calif., say they've achieved some promising results that suggest it's possible.
Fusion is the reverse of fission, in which two light atomic nuclei are fused together instead of one nucleus being split apart. It's the way stars like the sun generate energy, and it promises a virtually unlimited power source — with less radioactive waste than nuclear fission — if it can ever be harnessed. That's what the NIF is designed to do, and thanks to the power of lasers, NIF scientists now say they're a step closer to getting there. They're developing inertial confinement fusion, or ICF, in which high-energy lasers heat and compress an inch-long gold fuel pellet called a "hohlraum." The hohlraum contains hydrogen nuclei, and NIF scientists hope to create enough heat that they'll achieve "ignition," in which the hydrogen isotopes fuse together in a self-sustaining chain reaction. If that happens, the researchers believe they can generate 10 to 20 times more energy than they need to power the lasers in the first place.
While that hasn't quite happened yet, the researchers have achieved two key steps in the ignition process: superhot "sun-like" temperatures and uniform compression, in which the targeted nuclei don't lose their shape (for these experiments, they used plastic spheres instead of hohlraums because they're easier to analyze). Associate NIF director Edward Moses says he hopes the facility will achieve actual ignition by spring or summer of 2012, but as PhysOrg reports, he has missed his own deadline before, having previously said he hoped to achieve ignition by the end of 2010.
Radiation poisoning is on everyone's mind these days, but as the Science Times points out, not all mutations are a bad thing. In fact, we wouldn't exist without them. The Times dedicates several articles today to the wonders of the animal kingdom — including humans — but one of the highlights is Carl Zimmer's look at how animals rose from a world of plants, and how the planet was never the same again.
We tend to take the existence of animals for granted, but they represent a remarkable leap in the progress of Earth's biosphere. As Zimmer writes, "The origin of animals was one of the most astonishing and important transformations in the history of life." Whereas life had previously been dominated by bacteria and algae in "microbial mats" floating through the ocean, animals introduced the concept of complex, animated life forms, often containing trillions of individual cells working together in amazing harmony. But things didn't start out that way — Zimmer links to a study in the current issue of Molecular Biology and Evolution, in which researchers show how single-celled organisms like Capsaspora might have evolved into today's big, complicated creatures.
As one biologist at the University of Arizona explains, the first multicellular animals may have evolved relatively easily. "All that has to happen is that the products of cell division stick together," he says. Single-celled organisms in colonies can go on to specialize in specific tasks, freeing up the whole colony to focus on big-picture issues — and perhaps even start evolving into animals. "It's not a hurdle," says German veterinary researcher Bernd Schierwater. "It's a very good way to be very efficient."
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Photo (still image of Fukushima plant on NHK TV news): NHK/ZUMA Press
Photo (nuclear cooling towers at dusk): David Wasserman/Jupiter Images
Image (hohlraum capsule bombarded with lasers): National Ignition Facility
Photo (museum display of various deer species): ZUMA Press