WASHINGTON — An obscure isotope known as Helium-3, which is used for everything from nuclear arms detection systems to medical imaging, is dwindling rapidly from an already limited supply.
Most of the Helium-3 in the United States is being used at border crossings around the country, which detect plutonium and other materials used to make nuclear arms. The substance is used in the more than 850 Radiation Portal Monitors that line the nation’s northern and southern borders
The isotope also plays a role in some road construction processes, oil-well logging, cryogenics (freezing materials at extreme temperatures) and physics research.
Scientists have been searching for a replacement, but because Helium-3 has such a wide array of uses, some fields of study, like nuclear materials detection, have found viable alternatives while others, including those involved in some general areas of physics research, are still searching.
“The entire neutron scattering world is in a crisis,” said Ronald Cooper, a scientist from the Oak Ridge National Lab.
Neutron scattering is a technique used in physics research whereby neutrons, tiny non-charged particles in the nucleus of an atom, probe a given material to create images that can’t otherwise be seen, much like an X-ray of bone structure.
“[Scientists who use Helium-3] are really going to be hurt,” Cooper said. “For security applications like portal monitoring, they have a solution, but for us, we give up a lot of performance for neutron scattering.”
Cooper said neutron scattering is vital to many different areas of science, and has helped lead to the creation of a wide range of improved products, from building better bridges to making better glue.
The oil industry may take a financial hit due to the shortage, as businesses chart the geologic formation of the land they are drilling using Helium-3-filled tubes (a process known as oil-well logging). The isotope can detect gamma rays in the surrounding rock, with low levels being the sign of a potential oil reservoir.
According to a recent presentation given by Brad Roscoe, a scientific adviser and nuclear program manager at the oilfield services provider Schlumberger-Doll Research, some oil rigs could lose up to $1 million a day if they stop drilling to test replacements for Helium-3.
The nuclear impact
Nuclear radiation detection systems at border crossings should not be affected, as scientists have found that Radiation Portal Monitors lined with alternative substances can effectively take the place of Helium-3 with minimal setbacks. In addition, Helium-3 does not degrade, meaning that machines already equipped with it will continue to be effective well into the future.
“The most important locations are already covered by [Helium-3] detectors,” said Steve Fetter, the assistant director at-large in the Office of Science and Technology Policy for the White House. “The substitutes will be designed to be as effective or almost as effective as helium tubes.”
If a radiation detection machine breaks, Fetter added, “it would have to be some electronic or mechanical failure, and at that point, you can recover the [Helium-3] and recycle it.”
Boron trifluoride is a potential alternative to Helium-3, but transportation restrictions have been placed on it due to its toxic properties. Boron-lined tubes, which are stainless steel with pure boron lining the inside, are not toxic, but have approximately one-seventh the sensitivity of Helium-3 tubes, according to a report by scientist Richard Kouzes of the Pacific Northwest National Laboratory in Richland, Wash.
Scientists said they are confident that both alternatives are viable, but acknowledged they were less efficient than Helium-3, which is considered the “gold standard.”
The vast majority of the Helium-3 stock comes from decayed tritium in nuclear arms stockpiles from the Cold War, meaning that the United States and Russia control most of the supply. It also means that the isotope is impractical to produce because there is no longer a nuclear arms race between the two superpowers.
The cost of producing 1 gram of tritium is estimated to be 20 to 100 times more expensive than the Helium-3 produced, according to Kouzes’ report.
The isotope can be found in nature, but is so scarce that it has little impact on the world’s supply.
“This stuff is essentially entirely man made,” said Gerald Epstein, the director of the Center for Science, Technology and Security Policy at the American Association for the Advancement of Science. “There is a lot more demand on it for the future than the supply we now have.”
The brokerage of Helium-3 in the U.S. is controlled by the Isotopes Program, administered by the Department of Energy. In 2008, the program doled out nearly 75,000 liters of the isotope, according to a presentation by Cooper. At the time, that was more than half of the total supply. In 2009, the program dispensed roughly 40,000 liters, or 53 percent of the previous year’s total.
In general, roughly 80 percent of the allotment is given out for neutron detection. In 2009, the Department of Energy gave 93 percent of the total for neutron detection technology, leaving all other industries just 7 percent of the total.