Archive for the ‘nuclear waste’ Category

sn-radwaste

It seems these days that no data storage medium lasts long before becoming obsolete—does anyone remember Sony’s Memory Stick? So have pity for the builders of nuclear waste repositories, who are trying to preserve records of what they’ve buried and where, not for a few years but for tens of thousands of years.

Today, Patrick Charton of the French nuclear waste management agency ANDRA presented one possible solution to the problem: a sapphire disk inside which information is engraved using platinum. The prototype shown costs €25,000 to make, but Charton says it will survive for a million years. The aim, Charton told the Euroscience Open Forum here, is to provide “information for future archaeologists.” But, he concedes: “We have no idea what language to write it in.”

Most countries with nuclear power stations agree that the solution for dealing with long-lived nuclear waste is to store it deep inside the earth, about 500 meters below the surface. Finland, France, and Sweden are the furthest advanced in the complicated process of finding a geologically suitable site, persuading local communities to accept it, and getting regulatory approval. Sweden’s waste management company, SKB, for example, spent 30 years finding the right site and is now waiting for the government’s green light to begin excavation. It plans to start loading in waste a decade from now, and will be filling its underground pits for up to 50 years.

While the designers of such repositories say they are confident that the waste will be safely incarcerated, the most uncontrollable factor is future archaeologists or others with a penchant for digging. Archaeologist Cornelius Holtorf of Linnaeus University in Sweden showed meeting participants an early attempt at warning future generations: a roughly 1-meter-wide stone block with the words “Caution – Do Not Dig” written in English with some smaller text explaining that there is nuclear waste below. But who knows what language its discoverers will understand in thousands or hundreds of thousands of years—or even if they will be human beings? Holtorf points out that a much earlier attempt to warn off future excavations, the Egyptian pyramids, were looted within a generation. “The future will be radically different from today,” says archaeologist Anders Högberg, who is also from Linnaeus University. “We have no idea how humans will think.”

In 2010, ANDRA began a project to address these issues, says Charton. It brings together specialists from as wide a selection of fields as possible, including materials scientists, archivists, archaeologists, anthropologists, linguists, and even artists—”to see if they have some answers to our questions.” The initial goal is to identify all the approaches possible; in 2014 or 2015, the group hopes to narrow down the possibilities.

The sapphire disk is one product of that effort. It’s made from two thin disks, about 20 centimeters across, of industrial sapphire. On one side, text or images are etched in platinum—Charton says a single disk can store 40,000 miniaturized pages—and then the two disks are molecularly fused together. All a future archaeologist would need to read them is a microscope. The disks have been immersed in acid to test their durability and to simulate ageing. Charton says they hope to demonstrate a lifetime of 10 million years.

Researchers have some time to work on the problem because the repositories will probably not be filled and sealed up until the end of this century. “Each country has its own ideas, but we need to get a common approach,” says SKB’s Erik Setzman. “We technical people can’t solve this problem ourselves. We need help from other parts of society.”

http://news.sciencemag.org/sciencenow/2012/07/a-million-year-hard-disk.html

Thanks to Dr. Rajadhyaksha for bringing this to the attention of the It’s Interesting community.

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A Norwegian company is breaking with convention and switching to an alternative energy it hopes will be safer, cleaner and more efficient. But this isn’t about ditching fossil fuels, but rather about making the switch from uranium to thorium. Oslo based Thor Energy is pairing up with the Norwegian government and US-based (but Japanese/Toshiba owned) Westinghouse to begin a four year test that they hope will dispel doubts and make thorium the rule rather than the exception. The thorium will run at a government reactor in Halden.

Thorium was discovered in 1828 by the Swedish chemist Jons Jakob Berzelius who named it after the Norse god of thunder, Thor. Found in trace amounts in rocks and soil, thorium is actually about three times more abundant than uranium.

The attractiveness of thorium has led others in the past to build their own thorium reactors. A reactor operated in Germany between 1983 and 1989, and three operated in the US between the late sixties and early eighties. These plants were abandoned, some think, because the plutonium produced at uranium reactors was deemed indispensable to many in a Cold War world.

Thorium is ‘fertile,’ unlike ‘fissile’ uranium, which means it can’t be used as is but must first be converted to uranium-233. A good deal of research has been conducted to determine if fuel production, processing and waste management for thorium is safe and cost effective. For decades many have argued that thorium is superior to the uranium in nearly all of the world’s nuclear reactors, providing 14 percent of the world’s electricity. Proponents argue that thorium reacts more efficiently than uranium does, that the waste thorium produces is shorter lived than waste from uranium, and that, because of its much higher melting point, is meltdown proof. An added plus is the fact that thorium reactors do not produce plutonium and thus reduce the risk of nuclear weapons proliferation.

Some experts maintain that the benefits of thorium would be maximized in molten salt reactors or pebble bed reactors. The reactor at Halden is not ideal for thorium as it is a ‘heavy water’ reactor, built for running uranium. But it is also a reactor that has already received regulatory approval. Many thorium supporters argue that, rather than wait for ideal molten salt or pebble bed reactors tests should be performed in approved reactors so that their benefits can be more quickly demonstrated to the world.

But is thorium really cheaper, cleaner and more efficient than uranium? And if so, do the added benefits really warrant the cost and effort to make the switch? Data is still pretty scarce, but at least one report is urging us to not believe the hype.

Through their National Nuclear Laboratory the UK’s Department of Energy & Climate Change released a report in September that stated: “thorium has theoretical advantages regarding sustainability, reducing radiotoxicity and reducing proliferation risk. While there is some justification for these benefits, they are often overstated.” The report goes on to acknowledge that worldwide interest in thorium is likely to remain high and they recommend that the UK maintain a “low level” of research and development into thorium fuel.

The place where thorium is proven either way could be China. The country is serious about weaning itself off of fossil fuels and making nuclear power their primary energy source. Fourteen nuclear power reactors are in operation in China today, another 25 under construction, and there are plans to build more. And in 2011 they announced plans to build a thorium, molten salt reactor. So whether it be Norway, the UK, China, or some other forward-thinking countries, we’ll soon find out if thorium reactors are better than uranium ones, at which point more countries may want to join the thorium chain reaction.

http://singularityhub.com/2012/12/11/norway-begins-four-year-test-of-thorium-nuclear-reactor/

Thanks to Kebmodee for bringing this to the attention of the It’s Interesting community.