Scientists turn nuclear waste into diamond batteries

Nuclear energy is carbon free, which makes it an attractive and practical alternative to fossil fuels, as it doesn’t contribute to global warming. We also have the infrastructure for it already in place. It’s nuclear waste that makes fission bad for the environment. And it lasts for so long, some isotopes for thousands of years. Nuclear fuel is comprised of ceramic pellets of uranium-235 placed within metal rods. After fission takes place, two radioactive isotopes are left over: cesium-137 and strontium-90.

These each have half-lives of 30 years, meaning the radiation will be half gone by that time. Transuranic wastes, such as Plutonium-239, are also created in the process. This has a half-life of 24,000 years. These materials are highly radioactive, making them extremely dangerous to handle, even with short-term exposure.

The typical nuclear power plant creates about 2,300 tons of waste annually. 99 reactors are currently employed in the United States. That’s a lot of waste per year. The US is currently stockpiling 75,000 tons of nuclear waste. It is carefully stored and maintained. However, just like anything else it is vulnerable to natural disasters, human error, even terrorism. Storage is also costly. American taxpayers are on the hook for tens of millions of dollars.

So what can be done? Researchers at the University of Bristol in the UK have a solution. Geochemist Tom Scott and colleagues have invented a method to encapsulate nuclear waste within diamonds, which as a battery, can provide a clean energy supply lasting in some cases, thousands of years.

How a nuclear power plant works.

Scott said there were no emissions, no moving parts, no maintenance, and zero concerns about safety. The radiation is locked safely away inside the gemstone. All the while, it generates a small, steady stream of electricity. Nickel–63, an unstable isotope, was used in this first experiment. It created a battery with a half-life of a century.

There are other substances which would last over ten times longer, while helping to reduce our nuclear waste stockpile. Older nuclear reactors, in service between the 1950s and the 1970’s, used graphite blocks to cool the uranium rods. But after years of service these blocks become covered in a layer of carbon-14, a radioactive isotope with a half-life of around 5,730 years. Once a power plant is decommissioned, those blocks must be stored as well.

By heating the blocks, scientists can turn carbon-14 into a gas, which would be gathered and compressed into a diamond—since diamonds are just another form of carbon, anyway. Each gemstone emits short-range radiation, which is easily contained by just about any solid material. Since diamond is the strongest substance on Earth, it can be safely stored inside. Researchers covered their work in a lecture at the university entitled, “Ideas to change the world.”

The diamond batteries only put out a small amount of current. They can’t replace contemporary ones quite yet. Scott told Digital Trends, “An alkaline AA battery weighs about 20 grams, has an energy density storage rating of 700 Joules/gram, and [uses] up this energy if operated continuously for about 24 hours.” Meanwhile, “A diamond beta-battery containing 1 gram of C14 will deliver 15 Joules per day, and will continue to produce this level of output for 5,730 years — so its total energy storage rating is 2.7 TeraJ.” Another stumbling block is cost, as anyone who has ever saved up for an engagement ring can attest.

Once these hurdles are overcome, possible applications include powering spacecraft, satellites, high- flying drones, and medical devices such as pacemakers—anything really where batteries are difficult or impossible to charge, or change. One tantalizing speculation: powered by such crystals, interstellar probes could operate even in the darkest reaches of space, where solar power is no longer feasible.

Applications abound. So much so, that Dr. Scott and colleagues are asking the public for other possible uses. Weigh in with yours at: #diamondbattery

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