Small robots could find big target: nuclear warheads

Finding nukes is a challenge. Swarming inspector bots could help.

A prototype nuclear warhead detector.

Imagine a swarm of robots, equipped with smart detectors, working together to identify nuclear weapons and report back to their masters.

It may sound like a scrapped story idea from Metal Gear Solid, but a team at Princeton University may have already cracked the case. On Tuesday, they announced the completion of a prototype “inspector bot”: a polyethylene plastic cylinder standing three feet tall, with three neutron counters and wheels to move in any direction.

The team is hopeful that it could pave the way for large-scale, automated systems that uphold arms-control agreements and support nuclear safeguards. Rob Goldston, Princeton Plasma Physics Laboratory physicist, said in a statement that with some more development, the robot could show how “simple and robust autonomous, mobile, directionally and spectrally sensitive neutron detectors could provide a cost-effective means to provide effective and efficient verification.”

The robot uses neutron counters placed 120 degrees apart. They are capable of measuring both the energy levels of neutrons and the direction from where they’re coming from. A low energy rating, for example, could suggest shielding.

The bot could prove useful in a number of situations. Uses cited by the team include detecting low-enriched uranium that could be used in a modified enrichment plant to create uranium for weapons. It could also protect gas centrifuge enrichment plants. It could also play a key role in disarmament treaties, detecting whether the expected number of warheads is accurate both before and after.

The neutron detector robot, standing tall.
The neutron detector robot, standing tall.

Robots have been shown to play a vital role in handling nuclear issues. Robots were employed to help clean up from the Fukushima nuclear disaster in 2011, although several broke down due to the high radiation levels. Other bots have been used to clean up from the Hanford nuclear site in 2017. One nuclear site in the UK has explored using insect-like robot groups to clean up after disasters, with their leftover metal forming part of the dangerous landscape.

Goldston and the team’s project has a slightly different benefit. For this robot, it’s less about entering dangerous spaces and more to do with automating an inspection process. The project dated back to 2014, when the team found out about another lab with a set of neutron detectors. The detectors activated when a truck carrying uranium gas ready for enrichment drove past.

The International Atomic Energy Agency encouraged the team to explore the idea further, and it eventually received funding from the U.S. Department of State.

From here, the team aims to develop systems that enable the autonomous swarm. That includes artificial intelligence that can guide the bots, as well as a communications system that can enable them to work together. The A.I. system is being developed by a team led by principal investigator Naomi Leonard. The main issue is developing a system that can decide whether to keep looking or to check out a weak signal when detected.

Robots have played a big role in cleaning up after nuclear accidents, but with this machine, it could minimize the risk of disasters even taking place.

Media via Elle Starkman, Princeton Plasma Physics Laboratory