Nuclear submarines are the ultimate weapon systems, used only by the military superpowers like Russia and the US. Protected by seawater, they can surreptitiously travel the globe, appearing on the spot to survey or fire missiles, including nuclear weapons. Powered by a nuclear reactor, they can sail under water for months.
But that nuclear reactor inevitably also reveals information by continuously emitting billions of neutrinos, ghost particles that can shoot right through the reactor wall, the hull and even the entire Earth.
Despite their elusive nature, neutrinos are increasingly detectable. Bernadette Cogswell and Patrick Huber, two physicists from Virginia Tech University in the US, to describe in the trade magazine Physical Review Letters how detection a few meters away from the submarine can reveal the fraction of leftover nuclear fuel.
This would also expose the removal of nuclear fuel, which is a violation of the Nuclear Non-Proliferation Treaty (NPT). In order to enforce this ban, a system of inspections has been set up of, for example, nuclear reactors for energy generation. One loophole in that arrangement is the nuclear submarine. These are secret military installations, so the treaty does not require controls on board. Until now, the existing nuclear powers have coincided with the owners of nuclear submarines, but non-nuclear power Brazil is also working on its own nuclear submarine, and Australia is getting some. They should be inspected.
With the new method, the nuclear submarine parks in the harbor above a neutrino detector on the bottom. Low-energy anti-neutrinos emitted during the decay of cerium-144 and ruthenium-106 can be detected with a detector of about 100 kilograms. The results indicate the amount of highly enriched nuclear fuel still in the reactor. This will have to correspond to the inspectors’ accounts.
Chinese patent
But the idea offers a possibility that goes much further: detection of sailing nuclear submarines. With that, the weapon would lose its greatest strength, stealth.
In 2014, a university in China patented a method to detect nuclear submarines with the help of neutrinos. There is also an American-British research project to monitor nuclear reactors tens of kilometers away using neutrinos.
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Still, the detectors need to become much more sensitive to be of practical use, says Jaime Karremann, editor-in-chief of the defense publication navalships.nl† “New detection methods are often presented, but few systems actually come onto the market,” he writes. “Indeed, the sensitivity of these neutrino detectors is still a shortcoming. You can’t do anything with a range of five meters. But once it’s a few hundred meters, it’s getting closer to being suitable as a sensor on the seabed of relatively shallow waters. choke points”, such as straits.