Chemical elements often exist in nature as a blend of different variants called isotopes. To be useful in most applications, a single isotope has to be enriched, or separated out, from the rest.
Now scientists have discovered a cheaper and more environmentally friendly way to enrich stable isotopes, which are used for medical imaging and nuclear power—and are some of the world’s most expensive chemical commodities.
A combination of factors have created a looming shortage of several stable isotopes. Last year, the Government Accountability Office released a report warning that there may soon be a shortage of lithium-7, a critical component of many nuclear power reactors.
Production of lithium-7 was banned in the United States due to environmental concerns. It’s unclear whether the current sources, found in China and Russia, will continue meeting global demand.
2,000 TIMES THE PRICE OF GOLD
One of the major sources of molybdenum-99, essential for medical imaging in tens of millions of heart, kidney, and breast procedures each year, is an aging nuclear reactor in Canada that’s expected to stop operating in 2016.
Other valuable isotopes are produced by Cold War era machines known as calutrons operating in Russia. Their extreme age, high operating costs and regional concentration further threaten global supply.
“Isotopes are among the most expensive commodities on Earth,” says Mark Raizen, professor of physics in the University of Texas at Austin and author of the study. “One ounce of a stable isotope that needs the calutron to separate it can run around $3 million.
“That’s roughly 2,000 times the price of gold. And that has held back certain medical therapies.”
MAGIS: THE NEW METHOD
Unlike the calutron, which requires huge amounts of energy to maintain a magnetic field with electromagnets, the new method for enriching stable isotopes, called MAGIS (magnetically activated and guided isotope separation), needs little energy due to its use of low-powered lasers and permanent magnets.
The new method, described in a study published in the journal Nature Physics, also has less potential for environmental effects than the chemical process used in producing lithium-7, which has been linked to mercury contamination.
Nuclear medicine in particular could benefit from the new method, the researchers say. Many stable isotopes are precursors to the short-lived radioisotopes used in medical imaging, cancer therapies, and nutritional diagnostics.
The new method also has the potential to enhance our national security. The researchers used the method to enrich lithium-7, crucial to the operation of most nuclear reactors. The United States depends on the supply of lithium-7 from Russia and China, and a disruption could cause the shutdown of reactors. Other isotopes can be used to detect dangerous nuclear materials arriving at US ports.
Now, Raizen’s top goal is getting this technology out of the lab and into the world. The MAGIS invention has been issued a US patent. Raizen plans to create a nonprofit foundation to license the technology.
“I believe this is world-changing in a way that is unique among all the projects that I have done. And I do feel passionately about it,” says Raizen. “There are many potential uses of isotopes that we don’t even know yet. But they’ve been held back because the price has been so high, or it’s been unavailable.”
The University of Texas at Austin funded the work.
《Demonstration of magnetically activated and guided isotope separation》, Published on Journal 《Nature Physics》in June 29, 2014.