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US, Russia, and China are developing next generation nuclear submarine fleets, other countries are also mastering nuclear submarine technology

A nuclear submarine is a submarine powered by a nuclear reactor. The performance advantages of nuclear submarines over “conventional” (typically diesel-electric) submarines are considerable. Nuclear submarines are more powerful than diesel-powered submarines because nuclear reactors powering them can run for years without the need for refuelling. Nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently as is necessary for conventional submarines and thus enhance their survivability  .


The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods of time; and the long interval between refuelings grants a range virtually unlimited, making the only limits on voyage times being imposed by such factors as the need to restock food or other consumables. Nuclear submarines are considered nemesis of Aircraft carriers, over the course of World War II; no less than seventeen aircraft carriers were sunk by submarines including seventeen were put down by U.S. submarines.


Unlike conventional submarines, nuclear submarines have greater mobility and autonomy and are essential for patrol operations in remote ocean areas. While conventional submarines move at a speed of six knots (about 11 kilometer per hour), nuclear-powered submarines can reach 35 knots—about 65 km per hour.


The development in the nuclear sectors has enabled a lot of countries to build nuclear-powered submarines to defend their borders. The high cost of nuclear technology means that relatively few states have fielded nuclear submarines. Some of the countries with nuclear submarines are the United Kingdom, Russia, India, United States, China, and France. The U.S. Navy has 70, Russia has 41 including the ill-fated deep-diving special submarine Losharik, on which 14 submariners lost their lives in July 2019. China is next with 19; Britain has 10; France, nine; and India, three.


Other countries such as Brazil and South Korea are also joining the club. Brazil’s nuclear submarine program leverages French design help, but with a local reactor. The initial boat, Álvaro Alberto, was laid down in 2018 and should be ready to join the fleet by 2029. South Korea’s intention was only revealed when it announced on October 2019  that they are considering it.  In January 2018 Tehran informed the U.N.’s nuclear watchdog, the International Atomic Energy Agency (IAEA), that it intends to “construct naval nuclear propulsion in the future.” Iran does have a local submarine building industry and has launched a series of successively larger submarines.


Modern submarine fleet is made up of three major types of boats: ballistic-missile submarines, attack submarines, and cruise-missile submarines, each of  which serves a specific purpose. The nuclear ballistic submarines are equipped with nuclear weapons capable of delivering a retaliatory or preemptive strike almost anywhere in the world.  Attack submarines take care of tactical missions like intelligence gathering, launching cruise missiles, and even sinking ships or submarines. Because attack submarines carry cruise missiles, they constitute a navy’s most crucial and versatile weapon in any frontal assault. Cruise missiles are designed to deliver a large warhead over long distances with high accuracy, and they are intended to hit both land and sea targets. Combined, these two types of submarines make up the preponderance of what will likely be the future of undersea warfare.


The world’s three largest naval powers are all developing the next generation of their nuclear submarine fleets, accelerating the underwater arms race between the United States, China and Russia.



Most submarines have two hulls, one inside the other, to help them survive. The outer hull is waterproof, while the inner one (called the pressure hull) is much stronger and resistant to immense water pressure. There are spaces in between the two hulls that can be filled with either air or water. These are called the ballast tanks and, with the diving planes, they give a sub control over its buoyancy, particularly during the first part of a dive or a return to the surface from the depths.


The strongest submarines have hulls made from tough steel or titanium. Submarines have fins called diving planes or hydroplanes to help them swim and dive. They work a bit like the wings and control surfaces (swiveling flaps) on an airplane, creating an upward force called lift.


A large military submarine has dozens of people onboard. A submarine is a completely sealed environment. The nuclear engine provides warmth and generates electricity—and the electricity powers all the life-support systems that submariners need. It makes oxygen for people to breathe using electrolysis to chemically separate molecules of water (turning H2O into H2 and O2). Subs can even make their own drinking water from seawater using electricity to remove the salt.


Submarines navigate using a whole range of electronic equipment: GPS satellite navigation, which uses space satellites to tell the submarine its position. There’s also SONAR, a system similar to radar, which sends out pulses of sound into the sea and listens for echoes reflecting off the seabed or other nearby submarines. Another important navigation system onboard a submarine is known as inertial guidance. It’s a way of using gyroscopes to keep track of how far the submarine has traveled, and in which direction, without referring to any outside information. Inertial guidance is accurate only for so long (10 days or so) and occasionally needs to be corrected using GPS, radar, or other data.


Submarines use diesel-electric engines or Nuclear power for propulsion. Most large military submarines are now nuclear-powered. Like nuclear power plants, they have small nuclear reactors and, since they need no air to operate, they can generate power to drive the electric motors and propellers whether they are on the surface or deep underwater.

Nuclear Reactor technology

Nuclear reactors are basically heat engines. As uranium fissions, the breaking apart of atoms releases energy, much of it in the form of heat, which can then be used to do work. In a nuclear-powered submarine, reactor heat produces steam to drive the turbines that provide the submarine’s actual power. The development of compact, safe, and highly reliable pressurized water reactors for naval use in the early 1950s was the major technological achievement that made nuclear-powered submarines possible.


Naval pressurized-water reactors include a primary coolant system and a secondary coolant system. The primary system circulates water, which is pressurized to keep it from boiling, in a closed loop. As water passes through the reactor, it is heated. It then goes through the steam generator, where it gives up its heat to generate steam in the secondary system. Finally, it flows back to the reactor to be heated again. Inside the steam generator, heat energy is transferred across a watertight boundary to the secondary system, also a closed loop. The unpressurized water in the secondary system turns to steam when heated. The steam, in turn, flows through the secondary system to the propulsion turbines, which turn the propellers, and to the turbine generators, which supply electricity. As it cools, it condenses to water and is pumped back to the steam generator


The People’s Republic of China navy fleets consist of both the nuclear powered and conventional powered submarines of which fourteen of the submarines are nuclear powered. The nuclear-powered submarines are categorized into ballistic and attack. The submarines are further placed into different classes namely type 091 Han class, 092 Xia class, 093 Shang, 094 Jin, 095, 96 Tang class, and type 098. Since 2002, China has built 10 nuclear subs: six Shang I- and II-class nuclear-powered attack subs – capable of firing antiship and land-attack missiles – and four Jin-class nuclear-powered ballistic missile subs, according to a 2017 US Defense Department assessment.



The Russian Navy has several nuclear submarines; some were inherited from the Gorbachev while others were built. In total, the Russian navy has 45 nuclear submarines in three categories attack, ballistic missile, and cruise missile submarines. The attack submarines in the Russian navy can also carry land nuclear cruise missiles.


United States

The United States has several nuclear submarines in three categories cruise missile, attack submarines, and ballistic submarine. From the first sub the US had, the Turtle, the advance in technology has enabled better submarines to be built. The US has 72 submarines in total which are further divided into class Los Angeles, Ohio, Virginia, and Seawolf.

The Navy currently fields 17 Virginia-class fast attack submarines, which are built to operate in the world’s littoral and deep waters. Virginia-class submarines can launch torpedoes at other submarines and at ships. They can also launch missiles at ground targets, gather intelligence, and deploy Navy SEAL units for special operations.



The Indian navy has only two nuclear submarines with other submarines powered by other means. The two are ballistic missile and attack submarine. The last submarine was leased from the Russians in 2012, and it is under the Indian Navy for ten years. The attack submarine is an Akula class 11 submarine named Chakra. The other sub is in Arihant class submarine and was commissioned in 2016. Both of the two submarines are active and in the water.


Brazilian Navy’s Nuclear Submarine

The Brazilian Nuclear Program gets a boost with the cornerstone laying of the Brazilian Multipurpose Reactor and the start of turbogenerator integration tests of the Electronuclear Energy Generation Laboratory (LABGENE, in Portuguese) in June 2018.


“They will build the 30-megawatt research reactor building, a radioisotope processing unit, a radiochemistry and neutron activation analysis laboratory, a neutron beam laboratory, and a waste treatment and storage unit, in addition to other support facilities for research and operation,” Perrotta said. It will take six years for the complex to initiate operations.


During the initial integration tests of LABGENE’s turbines, Admiral Eduardo Bacellar Leal Ferreira, MB commander, highlighted the importance of the laboratory as a prototype for the future nuclear submarine’s propulsion system. “As we improve the nuclear fuel process in the Brazilian industry, we will meet the needs of the naval force and society,” he said.


The officer also highlighted the impact of technology on health. “LABGENE strives to improve and master several common systems with RMB, including instrumentation, controls, and protection of nuclear systems associated with reactors,” said Rear Adm. Ferreira Marques.


According to MCTIC’s Communication Center, LABGENE will host the naval system tests for steam propulsion. “The Brazilian nuclear submarine is strategically important to the defense of Brazilian territory. In addition, the construction process benefits from the Navy’s proficiency in nuclear fuel cycle and reactor construction technology,” MCTIC’s Communication Center indicated.


According to MB’s Social Communication Center, construction of the nuclear submarine should be completed by 2029. The Submarine Development Center concluded the basic project in January 2017. The next phases, MB’s Social Communication Center indicated, will focus on details and construction.


The Brazilian nuclear-powered submarine will add a new dimension to the country’s naval power. “Thanks to its mobility and autonomy, the nuclear-powered submarine can monitor distant maritime areas, fulfilling Brazilian’s interests to protect its vast continental platform and deter hostile pursuits,” MB’s Social Communication Center pointed out.


Nuclear Submarine Trends

The nuclear submarine club is increasing year after year as countries around the world see the importance of having nuclear submarines for their security. The advancement in technology is also enabling submarines to be built with the top-notch technology.  The submarines that we’re seeing are much more stealthy and difficult to detect.


US’s Virginia class submarines are capable of launching drones and unmanned underwater vehicles. Russia’s Fifth generation nuclear submarine Husky is expected to be made of fundamentally new materials, and armed with hypersonic missiles


China is building AI-augmented submarine with “its own thoughts” would reduce the commanding officers’ workload, eliminate human error and give China’s navy a competitive edge in underwater battles, reported the South China Morning Post.



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