News | Apr 3, 2019

Helium-3 is scarce, this Navy invention stretches it for radiation detectors

Critical advancement in thermal neutron detectors is available to qualified companies for commercialization

A cargo truck drives through a radiation portal monitor at a Department of Homeland Security test area in Nevada.

National Nuclear Security Administration

Radiation portal monitors are used to detect the invisible gamma and neutron radiation and warn security officials of unauthorized movements of nuclear materials at borders and checkpoints.

Even the smallest atomic “dirty bombs” emit some neutron radiation, but the Helium-3 used in the thermal neutron detectors is in short supply. The only source of Helium-3 is decayed Tritium from a nuclear reactor, and only one reactor in the U.S. is producing it.

Each year, thousands of liters of Helium-3 gas is made available for government research, national security activities, and medical diagnostic procedures. But demand as high as 70,000 liters per year can outpace government supply, due to a substantial increase in the use of neutron detectors for homeland and national security applications, according to the Department of Energy.

But on Tuesday, the U.S. Navy was assigned U.S. Patent 10,247,848 for a new technology titled “Helium-3 Gas Proportional Counter,” invented by Drs. Brian Justus and Alan Huston of the Naval Research Laboratory, and Brian’s brother, Dr. Alan Justus of the DOE’s Los Alamos National Laboratory. (A PDF of the patent is available below)

The scientists discovered that rectangular gas tubes have more surface area for detection and are more efficient than cylindrical gas tubes in mating with the neutron detector’s polyethylene moderator.

But the more important discovery was that instead of pressurizing the gas tubes with lots of Helium-3, dense Xenon gas (or Krypton ) could be added, at lower pressures, which means more detectors can be built using smaller amounts of Helium-3.

“The engineering innovations taught in this invention will achieve an overall four-fold reduction in the consumption of Helium-3 and still achieve improved detector efficiency,” the patent states, with an estimated cost savings of $20,000 to $30,000 per detector.

In partnership with the Navy’s technology transfer program, TechLink, the Department of Defense’s national partnership intermediary for technology transfer, is ready to help businesses license the patented technology so they can make, use, or sell advanced radiation portal monitors.

Dr. Austin Leach, associate director of TechLink, has been in communication with the Naval Research Laboratory on the Helium-3 technology and has a list of companies to contact about licensing the technology.

“The market for the neutron detectors is solid and we’ll be discussing license agreements that see this advancement’s speedy transition back to it,” Leach said.

Licensing inquiries can be sent to Leach at or 406-994-7707.