Ultra Quiet: France’s New Stealth Nuclear Submarine, Revealed

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March 8, 2021 Topic: French Navy Region: Europe Blog Brand: The Buzz Tags: SNLE-3GFranceFrench NavySSBNNuclear SubmarineMilitary

Ultra Quiet: France’s New Stealth Nuclear Submarine, Revealed

France’s newest nuclear submarine will be quieter than ambient noise in the ocean—and able to detect the most subtle of underwater noises.

The difference between life and death underwater is noise: if a submarine can avoid detection, they’ll live to fight another day. If on the other hand a submarine is too noisy and can be heard, they’ll likely be sunk. Hence the reason why some of the newest Western submarine designs like the United Kingdom’s Dreadnaught-class or the United States’ Columbia-class are some of the quietest submarines in existence. Soon joining their ranks of ultra-quiet submarines? France’s SNLE-3G nuclear submarine.

The new submarine will carry the sea-based portion of Paris’ nuclear deterrent, replacing the older Triomphant-class. And thanks to reporting by H. I. Sutton, an expert on all things naval, some crucial SNLE-3G features have quite literally come to the surface.

First and foremost, they will be quiet—extremely quiet. A French naval officer explained just how silent the new submarine will be, elaborating that the sub’s “radiated noise may be less than the ambient noise in the ocean.” Unlike diesel-electric submarines which attempt to dampen the noise caused by operating onboard diesel engines, nuclear submarines try to reduce noise caused by pump machinery used to cool their nuclear reactor. Noise levels lower than ocean noise indicate either a pump system optimized for low noise output, improved sound-damping technology, or both.

In addition, the SNLE-3G will reportedly be capable of parsing out the minutest of underwater sounds and sorting through noise caused by surface traffic to give those onboard a detailed and far-reaching, high fidelity picture of what is happening underwater. This detection ability would be afforded by Thales’ ALICIA (Analyse, Localise, Identify, Classify, Integrate, and Alert), a sophisticated sonar suite that allows submarines to pay underwater games of cat and mouse more successfully.

Though ALICIA will allow the new SNLE-3G submarines to gather large amounts of sounds, artificial intelligence will be needed to sort through massive data sets and determine which sounds are relevant and which sounds are merely distractions, relieving the burden put onto sailors.

The French officer interviewed by H. I. Sutton explained how though the new nuclear submarine represents a significant step up when compared to the previous French nuclear submarines, the submarine builds on some the Triomphant-class’ characteristics:

“One important factor in designing SNLE-3G is the heritage. We take possession of the best of what our elders did, we modernize it and digitize it. SNLE-3G main difference will be its unique processing power and an incremental combat system which will be future proof and batch-upgradable throughout the life of the submarine. Each new batch will learn from the previous batches.”

The SNLE-3G is will enter service with the French Navy around 2035, and is expected to then serve until the end of the century. Once it does, it will likely be one of the quietest submarines in existence.

Caleb Larson is a Defense Writer with The National Interest. He holds a Master of Public Policy and covers U.S. and Russian security, European defense issues, and German politics and culture.

Image: Reuters.