"Lenin Youth Communist" submarine, the first nuclear-powered submarine of the Soviet fleet (Getty Images)

A naval weapon designed to operate on the surface and effectively in deep waters, powered by a small nuclear reactor onboard the ship.

Nuclear submarines are strategic weapons because they are technologically advanced, have strong destructive power, high speed, and can remain underwater for several months.

These submarines undertake various combat missions from offensive to deterrence. They can also efficiently carry out reconnaissance and intelligence gathering tasks, as well as special operations that are difficult to achieve through conventional means due to environmental, political, or geographical conditions.

Nuclear submarines themselves are not nuclear weapons, but are named after their power technology. However, they are one of the most dangerous elements of the so-called "nuclear triad," as they can be equipped with nuclear warheads launched from underwater platforms.

The ability of submarines to remain hidden and approach enemy targets without being detected is a key factor in enhancing surprise and deterrence.

By 2025, only six countries will possess nuclear submarines: the United States, the United Kingdom, Russia, France, China, and India. Other countries, including Australia and Brazil, are developing their own nuclear submarines.

Nuclear submarines themselves are not nuclear weapons, but are named after their fuel technology (Getty Images)

Development of Nuclear Submarines

Research into nuclear propulsion for naval vessels began in the 1940s. In 1954, the first nuclear-powered submarine, "Nautilus," was commissioned, marking the official application of nuclear power to submarines.

This technology spread rapidly. In September 1955, the Soviet Union's first nuclear submarine K-3, named "Lenin Youth Communist," was launched and commissioned in 1958.

In the early 1960s, the United States shared nuclear submarine technology with the United Kingdom, while France and China continued to develop it independently.

Over the following decades, the technology of nuclear submarines continued to evolve. Their size increased, engines became more efficient, safer, and easier to operate and maintain. Their performance improved, with faster speeds, less noise, and significantly greater diving depths.

While some countries continued to build conventional submarines alongside nuclear submarines, other countries, including the United States, the United Kingdom, and France, limited themselves to building nuclear submarines.

During the Cold War, the construction of nuclear submarines accelerated, as they were one of the pillars of the nuclear triad. By the end of the Cold War in 1989, the number of active and under-construction nuclear submarines exceeded 400.

In later years, due to technical reasons such as outdated systems and high operational costs, as well as nuclear arms reduction programs, about two-thirds of the submarines were retired. At the same time, these countries continued to commission a new generation of more advanced nuclear submarines.

Propulsion and Operating Systems

This nuclear submarine is powered by a small, portable nuclear reactor, which includes a compact pressure vessel with neutron and gamma ray shielding inside. This pressure vessel is designed to accommodate a relatively large naval reactor, approximately 4.6 meters high and 1.8 meters in diameter, with a core section 1 meter high and 1.2 meters in diameter.

In larger submarines, the power range of naval reactors varies from 10 megawatts to 200 megawatts. The nuclear fuel has high efficiency, requiring only a small amount of fuel supply at startup, and usually does not need refueling throughout the submarine's service life.

Naval nuclear reactors rely on enriched uranium-235 fuel, typically using uranium-235 with an enrichment level between 20% and 50%. The latest American submarines have uranium-235 enrichment levels above 90%, while the latest French naval fuel has been reduced to 7.5%.

In general, China and France rely on low-enriched uranium (below 20%) to power their nuclear submarines, while the United States, Russia, India, and the United Kingdom use high-enriched uranium (above 20%).

The working principle of the nuclear reactor is to bombard uranium-235 with neutrons, causing some atomic nuclei to split, releasing heat energy and more neutrons. These neutrons continue the fission process, forming a so-called "nuclear chain reaction," producing constant and safe heat energy.

The heat generated by the chain fission process is used to produce high-pressure steam, driving the propulsion turbines, providing the rotation needed for the propeller and the submarine's internal systems. Additional turbines can also generate electricity for the submarine.

Advantages and Disadvantages

Nuclear submarines have many advantages, the most significant of which are:

  • No need for continuous refueling: After commissioning, the submarine is equipped with enough uranium fuel to produce energy for at least ten years, and the submarine may not require refueling during its entire service life.
  • Speed: The high efficiency of nuclear power allows the submarine to cruise at over 20 knots, enabling it to keep up with fast surface ships, a speed that conventional submarines cannot reach.
  • Operational range: Its characteristic of being able to conduct long-range patrols and remain submerged for months makes it possible to stealthily approach targets without being detected. This feature also enables it to deploy to farther distances.

Although nuclear submarines have significant advantages, there are factors that limit their widespread possession, the most obvious of which are:

  • The cost of building a nuclear submarine is extremely high, reaching billions of dollars, which poses a major obstacle to large-scale deployment.
  • Nuclear submarines require highly skilled labor with expertise in nuclear science to manufacture and maintain, making production and maintenance more complex.
  • Nuclear submarines are relatively large in size, limiting their ability to navigate in shallow waters, especially when maintaining stealth without surfacing.
  • Nuclear submarines' reactors are very noisy, making their acoustic stealth capabilities less effective than those of conventional submarines.
  • In addition to the challenges of safely disposing of nuclear waste and spent reactors, nuclear submarines also require additional precautions to prevent nuclear radiation.

Superiority over Conventional Submarines

The unique feature of nuclear submarines is their ability to remain submerged for extended periods, whereas conventional submarines can only stay underwater for a few hours. They must periodically surface to absorb oxygen and expel exhaust to drive diesel engines and charge batteries, especially after high-speed navigation.

Conventional submarines must also occasionally dock at ports for refueling, which limits their ability to operate at sea for extended periods. This requires careful planning of refueling methods, locations, and times.

The United States' first nuclear-powered submarine "Nautilus" (French media)

Nuclear submarines have military and strategic advantages that give them a clear advantage over conventional submarines. They can easily pursue and attack fast naval ships, while conventional submarines must quietly and slowly approach the target to avoid depleting battery power. This prevents them from engaging most fast surface ships, such as aircraft carriers and battleships.

To save battery power, conventional submarines must remain above water until the target is almost out of sight. Then, they submerge and proceed towards the target at a very slow speed (no more than two or three knots) to avoid consuming battery power. This power must be saved for escaping if attacked, at which point the submarine must use all underwater power to avoid retaliation.

For nuclear submarines, the nuclear reactor provides the energy needed to quickly approach the target and also allows them to escape at maximum speed indefinitely after an attack.

Countries Possessing Nuclear Submarines

As of 2025, only six countries in the world possess nuclear submarines:

  • United States

The United States commissioned its first nuclear submarine, the "Nautilus," in 1954. Since 1959, the United States has stopped using conventional submarines and has fully converted its navy to nuclear submarines.

According to data from the Nuclear Threat Initiative website, as of August 2024, the United States has the largest nuclear submarine fleet, consisting of 71 submarines. This fleet consists of four classes: Ohio-class, Los Angeles-class, Seawolf-class, and Virginia-class.

According to an article on the Pentagon website in March 2025, submarines are the cornerstone of the U.S. nuclear triad, responsible for about 50% of the country's nuclear warheads. They are divided into three types:

  • Ballistic missile submarines: 14 Ohio-class submarines, the largest and most secretive submarines, capable of launching nuclear warheads.
  • Missile submarines: 4 Ohio-class submarines, capable of launching Tomahawk missiles and secretly deploying special forces when needed.
  • Attack submarines: The largest class in the U.S. fleet, consisting of 53 submarines from the Virginia, Seawolf, and Los Angeles classes. Their missions include launching missiles, monitoring, destroying enemy submarines and surface ships, participating in mine warfare, and supporting ground operations and aircraft carrier battle groups.
  • United Kingdom

The United Kingdom commissioned its first nuclear submarine, the "Dreadnought," in 1963. According to a report from the UK government's official website on August 11, 2025, the entire British fleet is nuclear-powered, consisting of 11 "Astute" and "Vanguard" class submarines.

The United Kingdom has two types of nuclear submarines:

Attack submarines: These are conventional weapon submarines, with seven "Astute" class submarines. Their missions include enhancing the UK's nuclear deterrent, detecting hostile activities, supporting global operations, protecting naval task forces, and collecting intelligence and reconnaissance information.

Ballistic missile submarines: These are four "Vanguard" class submarines, whose mission is to maintain the UK's maritime deterrence. They are equipped with the "Trident II D5" missiles capable of carrying nuclear warheads.

  • France

France launched its first nuclear submarine, the "Le Redoutable," in 1971. Since 1976, France has stopped using conventional submarines and continues to produce conventional submarines for export.

According to data from the World Nuclear Association (February 2025), the French Navy has a fleet of ten nuclear submarines, representing the country's strategic deterrent force.

This fleet consists of four "Triomphant" class ballistic missile submarines equipped with nuclear warheads, as well as six attack submarines: one "Rubis" class submarine, two "Amphitrite" class submarines, and three "Barracuda" class submarines (Suffren, Duguay-Trouin, and Tourville).

  • Russia

The Soviet Union commissioned its first nuclear submarine, K-3 (the "Lenin Youth Communist"), in 1958. Although the Soviet Union mainly relied on nuclear submarines, it also used conventional submarines to a limited extent. After the dissolution of the Soviet Union in 1991, Russia continued to implement a policy of joint operations between nuclear and conventional submarines.

The Russian Navy has one of the largest submarine fleets in the world, estimated to have 64 submarines, including about 30 nuclear-powered submarines, including multiple classes of attack and missile submarines such as Delta, Borei, Akula, and Yasen.

  • China

China began constructing nuclear submarines in 1968 and successfully launched its first nuclear-powered attack submarine - the 091 class "Han" within two years. However, the Chinese Navy's submarine fleet is not limited to nuclear submarines, and Beijing has been continuously building and purchasing conventional submarines.

According to data from the World Nuclear Association (February 2025), China has approximately 12 nuclear-powered submarines, including six "Shang" (093) class and "Tang" (095) class attack submarines, as well as approximately six "Jin" (094) class and "Jin" (096) class ballistic missile submarines.

  • India

India began constructing nuclear submarines in 1998 and launched its first nuclear submarine, the "Arihant," in 2009. By the fall of 2024, India's submarine fleet will have two nuclear submarines, which are an important part of India's deterrence strategy, intended to carry nuclear warheads.

Safety and Risk Standards

Countries adhere to strict safety standards when designing naval reactors. The construction of submarine reactors must be able to withstand shocks and vibrations caused by water disturbances or offensive actions that the submarine might encounter.

The reactor compartment is designed to prevent any radiation leakage, ensuring the safety of the crew. Personnel are prohibited from entering the reactor compartment during operation. Engineers must follow strict safety procedures and use radiation monitoring equipment that is regularly checked.

However, the operation of nuclear-powered submarines still carries risks, posing a threat to human lives and causing permanent damage to the environment.

According to an article published on the website of the British organization "Scientists for Global Responsibility," the radiation released by submarine reactors poses a significant risk to the lives of people nearby and threatens public safety within a 1.5-kilometer radius of the submarine.

Nuclear submarines face various risks, including reactor damage, release of radioactive materials, and failures in cooling systems leading to melting of reactor fuel at high temperatures, which not only pose serious threats to the safety of the submarine crew but also affect the safety of the submarine itself.

The maintenance, overhaul, and refueling of nuclear submarines, as well as the dismantling of these submarines, the removal of nuclear waste, and the handling of spent nuclear reactors and nuclear waste, pose serious risks to the environment and nearby human communities.

During the refueling phase, fuel rods need to be removed from the high-radioactivity reactor core. For this purpose, the protective cover must be removed, exposing the reactor core, which may release radioactive particles or gases into the atmosphere.

Accidents can also occur during this process, causing explosions and releasing high concentrations of radiation, such as the accident that occurred in 1985 with the Russian K-431 submarine during nuclear fuel refueling in Vladivostok, resulting in 10 deaths and 49 people suffering from radiation exposure.

In 2025, the UK Ministry of Defence admitted a nuclear accident at the Clyde naval base, resulting in the actual or large release of radioactive material into the environment between January and April of that year.

According to The Daily Telegraph, this incident raised serious concerns about the maintenance of nuclear submarines, especially considering similar incidents in the past. The UK Ministry of Defence reported two such incidents between 2006 and 2007, and another in 2023.

Historically, Soviet nuclear submarines experienced multiple serious accidents during their development, five of which caused irreparable damage to the reactors, and several others resulted in the release of radioactive materials, causing dozens of deaths.

In 1963, the U.S. submarine "Thresher" sank with 129 people on board, considered one of the worst submarine accidents in history. It is believed that the cause was a failure in the welding of a pipe joint, allowing seawater to enter the submarine, disrupting its electrical system and ultimately causing the submarine's nuclear reactor to shut down.

The sinking of a nuclear submarine can permanently pollute the marine environment. Between 1970 and 1989, five Soviet nuclear submarines sank, resulting in the deaths of dozens of Soviet sailors and officers. The sunken submarines released radioactive materials, posing a continuous threat to the marine environment and navigation.

In 2003, the nuclear submarine "K-159" (known in the West as the "November" class) sank, leaving about one ton of nuclear fuel deposited on the seabed at the mouth of the Kola Bay, posing a threat to the nearby marine environment and fisheries.

Sources: Electronic website

Original: https://www.toutiao.com/article/7541808932830954035/

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