What's new in production

 Vol. 232 No. 10

The old Volkswagen Beetle had an oil-temperature light on the dash with a simple function. As a mechanic told me, “When the red light comes on, the situation is desperate. Shut off the engine and coast.”

Today, there is a critical shortage of helium-3, regular helium’s lighter, more elusive cousin. The supply crunch was probably inevitable. The crisis, however, was entirely man-made, and somebody should have noticed before the red light came on. 

A rare commodity. Helium-3 was predicted to exist long before it was actually found. When finally isolated in 1939, it was found to be just as stable, neutral and harmless as helium-4. The 3He atom consists of two protons and one neutron, and it has properties different from helium-4. For one thing, it boils at just 3.19°K. A “helium-3 refrigerator,” used in cryogenics, can cool to an unimaginably chilly 0.2°K.

There just isn’t very much of it. Helium-3 comprises 0.000137% of naturally occurring helium on Earth. It exists in the atmosphere at 7 parts per trillion.

Where does it come from? It is not extracted from natural gas because of prohibitive costs. All the stocks of 3He in the US come from the decay of tritium, a radioactive isotope of hydrogen (3H), which is used in nuclear weapons to boost their yield. Tritium has a half-life of 12.32 years and decays to helium-3 by beta decay, so that about 5.5% of tritium stocks decay to helium-3 every year. That “contaminant” must be removed or it diminishes tritium’s effectiveness. For years, it was just vented to the atmosphere.

The US tritium stockpile is maintained by the National Nuclear Security Administration (NNSA), an agency within the Department of Energy. Since 1980, NNSA has provided helium-3 to DOE’s Isotope Program to sell to customers primarily in medicine, science and petroleum exploration. After 1988, with the Cold War winding down, the production of new tritium supplies was curtailed, and the one reactor that produced it—Savannah River Site in South Carolina—was shut down. After that, helium-3 came from the dismantling of the nuclear weapons stockpile.

Changed priorities. The events of 9/11 focussed attention on one specific property of  helium-3. When a tube is filled with 3He and high voltage is applied, the gas becomes highly sensitive to neutron radiation. Enriched plutonium emits lots of neutrons, and there was suddenly great interest in knowing if plutonium was being transported into or within the country. Helium-3-based radiation detection portal monitors were deployed to screen cargo and vehicles at ports, airports and border crossings to spot the smuggling of nuclear material. The Department of Homeland Security (HSE) alone has deployed over 1,400 of these radiation detectors around the US.

Meanwhile, medical researchers were finding new ways to use 3He in diagnoses of lung disease, scientists were finding more reasons to chill substances to near 0°K, and petroleum engineers were improving the science of well logging.

No good substitutes. Just like in radiation monitors, the usefulness of helium-3 for well logging tools is in its high neutron-detection capability. Well logging instruments generally use two measurements downhole, one based on gamma rays and the other on neutrons. The gamma ray device measures the bulk density of the formation, but if gas or low-density hydrocarbons are present there is a tendency to overestimate formation porosity. The helium-3 instrument is very sensitive to hydrogen, which has the effect of slowing down neutrons, so it estimates pore fluid rather than density. Together, these two measurements increase the accuracy of the porosity estimate. Another advantage to helium-3 devices is that they can be made small and very robust, withstanding vibration, shock and high temperatures. Unfortunately, there aren’t any obvious substitutes.

Wake-up call. Industries that depend on helium-3 sailed along in a fool’s paradise until there was a hard dash of cold water in 2008. A company that was building radiation detectors for the HSE informed the agency it could not fulfill its contract because it couldn’t obtain sufficient helium-3 from the Isotope  Program. In 2000, there had been over 200,000 liters stockpiled. And now they were running out.

The math is pretty simple.  NNSA can produce about 8,000 liters per year from tritium decay. Demand has been running at 40,000 liters per year. “It is not a sustainable situation,” said a spokesman for the Office of Science and Technology Policy.

All public auctions of helium-3 were stopped, and DOE began rationing available stocks to the various industries. There are about 31,000 liters in storage, and the oil and gas industry has been allocated just 1,000 liters this year, which does not come close to demand. Russia, the only other large producer, has stopped exporting helium-3. Before the 2008 crisis, it sold for about $85/liter. A recent quote from a supplier was north of $10,000/gram.

The reasons this situation was not noticed in a timely manner can be pinned on terrible communication, according to the Government Accountability Office. In a report issued this spring, GAO said NNSA never told the Office of Science that inventories were nearly depleted, because that information was considered classified. The OS never informed NNSA how fast demand was growing, and neither department considered helium-3 to be part of their mission.

An interagency policy committee was formed, which stopped allocations of helium-3 for domestic radiation detection, and gave first priority to applications for which there are no current alternatives to helium-3. Second priority is given to radiation detection in foreign ports. Well logging has moved pretty far back in the line. Helium-3 is available, for a price, and engineers are scrambling to find alternative technologies. Meanwhile, the red light is on, and coasting is not an option. 

henry.terrell@gulfpub.com