Replacing Le Triomphant: Frence Begins Construction of Next-Generation Nuclear Submarine (SNLE 3G)

France has started building a new type of nuclear-powered ballistic missile submarines known as the SNLE 3G. This submarine is equipped with cutting-edge stealth technology, superior sonar, and the most modern missiles and torpedoes, ensuring France's nuclear deterrence well into the twenty-first century. However, many elements remain unknown, adding to the suspense surrounding this big enterprise.

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Joseph P Chacko
Joseph P Chacko
Joseph P. Chacko is the publisher of Frontier India. He holds an M.B.A in International Business. Books: Author: Foxtrot to Arihant: The Story of Indian Navy's Submarine Arm; Co Author : Warring Navies - India and Pakistan. *views are Personal

The French shipbuilding business Naval Group has begun constructing a third-generation strategic nuclear-powered submarine, which is scheduled to replace the ageing “Le Triomphant” class ships after 2035.

The construction of the first third-generation ballistic missile nuclear submarine (Sous-marins nucléaires lanceurs d’engins de troisième génération – SNLE 3G- SNLE 3G (SSBN 3G)) began on March 20th in Cherbourg, attended by Emmanuel Chiva, General Delegate for Armaments, Admiral Nicolas Vaujour, Chief of Staff of the French Navy, General Vincent Pons, Deputy Chief of Staff “Plans” of the Joint Chiefs of Staff, Pierre-Éric Pommellet, CEO of Naval Group, and Loïc Rocard.

This programme, critical to the future of French deterrence, was officially launched in February 2021 under the project management of the Directorate General of Armaments (DGA) in collaboration with the Military Applications Directorate of the Atomic Energy and Alternative Energies Commission (CEA) for the nuclear propulsion component, with Naval Group and TechnicAtome as lead contractors. The SNLE 3G will respond to the growing danger over the next 50 years, notably in invulnerability (discretion and stealth), and it will carry the most recent variants of the strategic missile M51, the Ministry of the Armed Forces noted at the time.

Since 2014, attempts have been made to create a modified version of the M51 missile known as M51.3, which is projected to reach service in 2030 and will likely be placed on the first SSBNs in the SNLE 3G programme.

Building an SSBN is a technological challenge because it entails cohabiting a nuclear power plant with a “space” centre in a tube roughly 150 metres long, all while emphasising secrecy and detecting capabilities. Developers of the next generation of submarines face significant obstacles. For example, in December 2013, the Military Programming Law stated that the most major vulnerability for submarines today is acoustic detection, which “prevents the submarine from being more stealthy.” Furthermore, in a speech at the French National Assembly on April 30, 2014, the Director-General of Armaments, Laurent Collet-Billon, stated that particles emitted in laughably small quantities by nuclear submarine reactors could one day be identified.

“Eventually, it will also likely be possible to detect surface disturbances caused by the movement of a submarine even at very low speeds and at great depths from space,” believes Collet-Billon.

In addition to the M51.3 ballistic missile, the submarine may be outfitted with the most recent F21 torpedo, also manufactured by Naval Group. The F21 is the world’s sole cutting-edge heavyweight torpedo, having significantly superior performance than other heavyweight torpedoes currently in service. It weighs 1.5 tonnes and has a range of 57 kilometres at a speed of 93 kilometres per hour. Its operational depth extends between 10 and 500 metres.

In addition, the submarine will be equipped with cutting-edge sonar technology. In February 2018, the Directorate General of Armaments awarded Thales a 42-month contract to conduct research and technology development for the future submarine’s sonar system. The contract will include the final verification of the fourth-generation side-scan sonar system, the creation of a new sonar with an adaptive latest-generation antenna, creative threat categorisation algorithms, and a novel nose-mounted antenna concept.

The installed forward and X-shaped rear rudders are comparable to the Columbia class. However, no other submarine has such large surfaces as the X-rudders. Overall, the design appears advanced and consistent with the rate of submarine development, yet it remains somewhat conditional. In terms of overall shape, it does not differ significantly from existing submarines. In addition, the sail enclosure appears to be more similar to the Scorpene class submarines than the Barracuda.

It’s also worth mentioning that the French have deviated from the Western trend of reducing their arsenal of ballistic missiles. The number of missiles on the British Dreadnought has been lowered from 12 to 8, and on the American Columbia, from 24 to 16. The French submarine will still carry 16 missiles. Thus, the submarine’s weaponry is based on prior concepts, and despite the addition of the most recent ballistic missiles and torpedoes, they reflect an evolution of earlier upgrades. French developers have prioritised hydroacoustics and stealth when developing new strategic submarines. The new French strategic submarine will most likely outperform the American Columbia-class submarine under development in these areas.

So far, unlike its British counterpart, which has extensively communicated about its four planned Dreadnought-class SSBNs, the Ministry of the Armed Forces has been relatively quiet regarding the SNLE 3G’s capabilities. It is only known that it will measure “about” 150 metres, 12 metres longer than the submarines of the “Le Triomphant” class, have a submerged displacement of 15,000 tonnes, and carry 16 strategic ballistic missiles of the M51 class.

The submarine’s increased acoustic discretion is due to a masking layer put on its hull to limit radiated noise in the water, unique magnetic discretion against airborne threats, and a new onboard environment processing unit. Its manoeuvrability and detecting capability will be enhanced compared to its predecessors, with Thales promising a technical advance in this area.

The information provided by the Ministry of the Armed Forces and the relevant industry on the submarine stirs more curiosity. Even the expense of this programme is unknown. At the end of the event commemorating the cutting of the first sheet metal, the Naval Group clarified that constructing the lead boat for the SNLE 3G programme would require 100,000 items and hundreds of km of cables and circuits. It underlined that such an accomplishment necessitates uncommon knowledge in technological and industrial areas, which only some countries possess.

However, some technological breakthroughs achieved for the SNLE 3G will assist the present “Le Triomphant” class submarines. According to Naval Group, this provides the highest performance throughout their operational life into the 2050s.

The Military Programming Law (LPM) 2024-2030 authorises the construction of four SNLE 3G. They will replace those now in service as they are gradually decommissioned to keep the Strategic Oceanic Force’s deterrent posture. According to the DGA, France will always have at least one SSBN on patrol, ready to carry out shooting orders within established deadlines. The French Navy intends to take charge of the first SNLE 3G in 2035. Subsequent vessels are to be delivered to the fleet at five-year intervals.

The French Navy currently has four submarines of the “Triomphant” class, the most recent of which entered service in 2010. This type of submarine has a submerged displacement of 14.3 thousand tonnes and measures 138 metres in length and 12.5 metres in width. It is equipped with a 150-megawatt K15 nuclear reactor.

The submarine can reach up to 25 knots and a diving depth of 400 metres. The “Triomphant” class ship is armed with 16 M51 ballistic missiles carrying TN 75 warheads with a power of 110 kilotons. In addition, the submarine has four 533-millimeter torpedo tubes that can launch torpedoes and anti-ship missiles.

Originally, building on the SNLE 3G was scheduled to commence in 2020. However, it appeared that the Naval Group did not have enough resources to complete building the sixth Barracuda-class submarine, freeing up resources for the new project. As a result, the first SNLE 3G was postponed until 2023. The first submarine was projected to enter service in 2030-31, ensuring the viability of oceanic deterrent until at least 2080. However, this is an unduly optimistic view. For example, the first Triomphant-class SSBN was laid down and commissioned 11 years ago.


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