Home COVER FILE How Should the National Submarine (MILDEN) Be? Conventional or Nuclear?

How Should the National Submarine (MILDEN) Be? Conventional or Nuclear?

by Buse Köse

M. Haluk BAYBAŞ / mhbaybas@gmail.com

Silent in depths

Submariner Motto

The Turkish Naval Forces and the defence industry are now taking steps for constructing the National Submarine (MILDEN) based on knowledge and know-how gained by their competent engineers and workers in the prideful materialisation of the National Ship (MILGEM) class corvettes and frigates. First of all, it is imperative to decide on the main propulsion system of the submarine to be constructed, as it will completely affect the design variables. At this point the important decision factor will be between the conventional diesel-electric propulsion system and nuclear power.

Before making this decision, let us examine the submarines and the submarine operation in general, which are quite different from the surface ships.

Submarine warfare encompasses the attack of conventional or nuclear-powered submarines with torpedoes, guided missiles, and nuclear weapons against hostile submarines, surface ships, and land targets by using advanced command-control and detection systems. In addition, other uses of submarines include covert reconnaissance, clandestine operations such as insertion of special force units to the target area, laying of mines covertly, and screening of the surface task force.[1]

Submarines traditionally fulfil their tasks individually, both to maintain their stealthiness and to increase operational effectiveness. Nonetheless, the desire to use this effective platform along with other units of the navy has always existed. However, this thought had been abandoned until recently due to communication constraints in the past. The classical usage has shown that sea denial and attacking the sea line of communication (SLOC) have been the main tasks of submarines. Today, especially nuclear submarines can be deployed effectively in a wider range of tasks such as escorting the aircraft carrier task group, reconnaissance, surveillance and intelligence gathering, support for special force operations, and attack with cruise missiles to land targets.

The most important feature of submarines is that they operate underwater and therefore they are difficult to detect. In other words, “stealthiness” is a crucial feature of submarines. Stealthiness allows them to both ensure self-defence and also develop surprise attacks against the enemy without being detected. It is vital to maintain stealth, especially for conventional submarines. Conventional diesel-electric submarines derive their underwater propulsion from electric motors powered by batteries. There is a need to operate at low speeds for the economic usage of batteries. In addition, it is rather inevitable that they can be located and attacked if they give a slightest indication of their position to hostile units. There are many examples of this situation in history. For this reason, it is essential that they do not give any indication about their presence and maintain their stealth until they conduct their attacks. Another weakness of conventional submarines is that they need to take fresh air from the surface by extending the snorkel at certain periods to recharge their batteries.[2] A snorkel on surface can harm their stealth. In particular, maritime patrol aircrafts (MPA) and naval helicopters can detect periscopes and snorkels by using their radar and infrared systems.

French Rubis-class submarines are one of the smallest-sized nuclear submarines.

Conventional submarines operates at low speeds in their patrol areas for the reasons stated above. Hence, a large number of conventional submarines are needed to be effective in large operational areas. Even so, conventional submarines are very effective and deterrent within the scope of the sea denial, especially in littoral waters[3]. In the maritime literature, conventional submarines are seen as important platforms for increasing the efficiency of smaller navies, especially those adopting sea denial. Since submarines can operate without prior sea and air control, they allow a weaker actor means to attack a stronger one.[4]

Nuclear-Powered Submarines

Nuclear-powered submarines are basically divided into two groups. The first group is nuclear-powered attack submarines (SSN), which use nuclear energy only for main propulsion, and as weapons they use torpedoes and guided missiles against ships, and cruise missiles against land targets. The second type of nuclear submarine is Nuclear Ballistic Missile Submarines (SSBN), which use both nuclear energy in the propulsion system and in intercontinental ballistic nuclear missiles as weapons. SSNs are used for conventional submarine warfare and sea control, whereas SSBNs serve within the scope of nuclear deterrence as a pillar of the nuclear triad. In this article, we are interested in nuclear-powered attack submarines, SSNs in the first group. Nuclear attack submarines can also be categorised under two groups. The first group includes SSNs that use mainly torpedoes as weapons; the second group includes SSGN[5]s that use both torpedoes and large amounts of cruise missiles. Nuclear attack submarines will be referred to as nuclear submarines from this point on.

Nuclear submarines are not subject to disadvantages such as low speed and power limitation. Flexibility, high speed, stealth, endurance, reach, autonomy, and punch (strike), which are expressed as ‘7 deadly virtues’ of nuclear submarines, carry them to a unique place.[6] They are directly used to establish sea control instead of sea denial. In fact, Russia calls these ships “nuclear underwater cruisers”.

Astute-class submarines serve in the United Kingdom’s SSN fleet.

Because they don’t need fresh air from the surface, they do not need to snorkel and can be constantly submerged and maintain their stealth, as well as conduct high-speed operations at deeper depths for extended periods of time (theoretically unlimited). As such, nuclear submarines enjoy both stealth and speed benefits. These features provide them with significant advantages during operations. For example, even if the periscope of a nuclear submarine is detected, it can easily break its track away after its own attack by making high-speed evasive manoeuvres for a long period of time. A nuclear submarine that manoeuvres at 30 knots in the deep can be anywhere within a 30-mile diameter in half an hour. This circle expands in favour of the submarine with each passing minute and as a result it becomes increasingly difficult to find it. In addition, the submarine can detect any hostile torpedoes instantly and avoid them with high speed.

Nuclear submarines can operate in vast areas and cover long sea passages in a short time, thanks to their capability to cruise at higher speeds for unlimited period of time. They can be deployed to different missions in a row, just like surface ships, and their tasking areas can be changed in a short time thanks to easier communication with the command headquarters due to their confidence in not to hesitate to disclose their positions. Nuclear submarines can accompany aircraft carrier or surface task groups as they have the advantage of stealth and speed, and can provide support in front or around the group. All these features provide flexibility for both the submarine commander and decision-making mechanisms at shore headquarters.

Severodvinsk, one of Russia’s Project 885 Yasen class submarines.

Nuclear submarines can be constructed on a larger scale since they do not have energy, power, and high speed restrictions. Thus, they can carry more torpedoes and guided missiles, providing power projection with significant firepower. With their high firepower, they can attack land targets from long distances without being detected. Likewise, they can carry out more extensive special force operations thanks to the capacity of large living spaces. Nuclear-powered submarines can be deployed to cover large operational areas of almost hundreds of miles.

Large navies turned to nuclear-powered submarines a long time ago because of some of the weaknesses of conventional submarines. While the USA, UK, and France only have nuclear in their inventory; Russia, China, and India have both nuclear and conventional submarines.

One of the highlights of the Falklands War between the UK and Argentina in 1982 was the sinking of the Argentine cruiser General Belgrano with 2 torpedoes by the British nuclear attack submarine Conqueror. As we see in this incident, a nuclear submarine, following the outbreak of the crisis, arrived in the southern hemisphere in a short time, found the most important unit of the enemy, after exchanging the necessary reports and orders with the command headquarters, attacked and sank it, and then ensured its own absolute survival. Only a nuclear submarine could accomplish this task. On the other hand, the conventional submarines in Argentina navy, one of which was made in the USA (Santa Fe (S-21)) and the other was of German origin Type-209 San Luis (S32), failed to show any success during the war and could not sink any ships.

Santa Fe, after it was detected via radar by a British anti-submarine warfare (ASW) helicopter, was attacked with depth charges as well as unusual weapons for use against a submarine such as machine gun and air to surface missile. San Luis carried out torpedo attacks on the British frigates it detected on 1 and 10 May, but failed as a result of the flaws of the torpedoes and the implementation of torpedo countermeasures by the targets.

From a tactical point of view, it is not possible to provide full submarine coverage around the Falkland Islands with only 2 conventional submarines. As we mentioned before, conventional submarines operate in allocated areas. If enemy ships enter their area, they can develop an attack, otherwise they can pass the war without engaging any target. The fact that San Luis has encountered enemy ships only twice during its time on the battlefield was an example for this situation. In fact, Argentine submarines were unable to establish any contact with British aircraft carriers, which had to be their primary targets. If Argentina had owned only one nuclear submarine, it could have changed the fate of the war with the 7 deadly virtues.

Virginia-class SSN of the US Navy.

Nuclear submarines are unique battle platforms with their features we have mentioned. From essentially a “lone wolf” a decade ago, the submarine is now nearly universally accepted as a key node within network-centric warfare, the purveyor of “undersea dominance,” and an essential element of Sea Power.[7]

Situation in the World

Currently, six countries have nuclear submarines. These are the United States, Russia, France, United Kingdom, China, and India. 68 nuclear-powered submarines in the USA, 36 in Russia, 19 in China, 11 in the United Kingdom, 10 in France, and 3 in India are operating and new ones are being built. There are also some other countries that work on nuclear submarines, such as Brazil and the Republic of Korea. Brazil takes the French design as ship type and builds it with its own reactor. The ship Alvaro Alberto was laid down in 2018 and is expected to enter service in the 2030s. The ship will be 100 metres long with a displacement of 6,000 tons and will be equipped with a 48 MW nuclear-electric propulsion system.[8] The Republic of Korea announced its intention in 2019 to build a nuclear-powered submarine. Australia is seen as another potential country.[9] [10]

Nuclear powered attack submarines vary in size. The smallest, the French Rubis class submarines, has a displacement of 2,600 tons and a length of 73.6 meters. As of 2018, there are 35 Los Angeles class submarines in the US navy inventory with a displacement of 6,900 tons and a length of 110 metres; Russia’s Yasen class submarines with a displacement of 13,800 tons and a length of 130 metres; the United Kingdom’s Trafalgar class submarines with a displacement of 5,200 tons and a length of 85.4 metres; India’s Arihat class submarines with a displacement of 7,000 tons and a length of 111 metres. The required reactor power can be up to approximately 500 MW depending on the size of the ship. The reactor of the French Rubis, one of the smallest nuclear submarine types, has a power of 48 MW. Considering that the Akkuyu nuclear power plant is 4,800 MW, it can be concluded that the reactor in the submarine is quite small, at the rate of one percent. In other words, we can say that construction, operation and maintenance of the reactor will be easier and less costly.

Los Angeles-class SSN of the US Navy.

Technological Infrastructure in Turkey

In Turkey, at Gölcük Shipyard, 3 AY-class, 4 PREVEZE-class and 4 GÜR-class conventional submarines have been built under German license since the 1980s. Finally, 6 REIS-class submarines, called Type-214TN in the international literature, are being built at Gölcük Shipyard.[11] During this whole process, sufficient experience and knowledge has been gained on a difficult and special method of shipbuilding. Besides, various projects such as GENESİS (Gemi ENtegrE Savaş İdare Sistemi) CMS, MÜREN (Millî Üretim Entegre Sualtı Savaş Yönetim Sistemi) submarine CMS, and all other critical mission software have become developable in Turkey. In addition, torpedoes and guided missiles have also been developed nationally. The only remaining critical need is the construction or supply of the nuclear power reactor.

The Turkish Atomic Energy Authority is the institution responsible for determining all kinds of policies related to nuclear energy in Turkey. Among the duties of the institution established in 1956;

  • To prepare national policy and strategy proposals to be followed in the use of nuclear energy technologies for the benefit of the country,
  • To carry out or have carried out all kinds of research, development, innovation, design, technology acquisition, production, testing, domestication works that will make it possible to benefit from nuclear energy, radiation, and accelerator technologies in the scientific, technical, and economic development of the country,
  • Cooperating with public institutions and organisations, universities and private sector organisations and carrying out joint projects in this context.[12]

There are departments and institutes of higher education in nuclear energy, the oldest being the Nuclear Energy Engineering Department of Hacettepe University in Turkey. In addition, nuclear reactors have been operated for training and research purposes. Of these, there are 2 reactors at Çekmece Nuclear Research and Training Centre, and a research reactor (Triga Mark II) at the ITU Energy Institute. Meanwhile, the first unit of the Akkuyu Nuclear Power Plant, which is under construction, is expected to enter into service in 2023. In conclusion we can say that Turkey has sufficient staff, infrastructure, knowledge and experience in the operation and management of nuclear energy.

Nuclear submarines can also play a role in bringing special force units to the target area. The US Navy’s Virginia-class SSN, USS North Carolina (SSN 777), is pictured during a drill off the coast of Hawaii.

National Submarine

Turkey aims to develop its own unique submarine within the scope of the National Submarine (MILDEN) project based on the capabilities gained in the field of defence industry. Great effort, time and resources will be spent for the works to be done within the scope of the project. The propulsion system shall constitute one of the basic factors in the design of the ship. Once the diesel-electric propulsion system is initially decided, it will not be possible to switch to the nuclear propulsion system later on. Therefore, it should be considered very carefully when deciding on the propulsion system. It is most desirable that the capability to be acquired with MILDEN will pay off the intensive effort that will be spent during the realization of the project. For this reason, the advantages of constructing a couple of nuclear submarines rather than a large number of conventional submarine, and the additional operational capabilities to be gained with the “strategic and psychological deterrence” to be obtained should be taken into account.

It can be argued that nuclear power submarines have high costs. Considering the cost issue from open sources, there are different figures such as $377 million for the French Rubis class nuclear submarine, $1.59 billion for the US Los Angeles class submarine, $2.5 billion for the UK Astute class submarine, and $800 million for Russia’s Yasen class submarine. Factors such as the size, technology, and the country in which the ship was built are effective in this regard. Especially the high labour costs in the western countries are noteworthy in price differences. In open sources, the cost of a conventional diesel-electric submarine with air independent propulsion (AIP) system is around 500 million dollars.

When we compare the operational efficiency, it is obvious that a nuclear submarine can be effective over a much larger area than conventional submarines, can change patrol areas very quickly and reach distant places faster.

Considering the MILGEM project, we can estimate that a period of at least 8-10 years may be required for ship design; and the construction of a submarine can be completed in 5 years. In other words, if launched today, the first ship will be ready 15 years later. The personnel such as officers, engineers, operators, technicians in the navy can be trained in nuclear energy, and the necessary infrastructures and facilities can be prepared during this time. The nuclear reactor needed for the ship could be developed domestically with some technology transfer, or procured from abroad just like nuclear power plants.


As a result, we can assert that it will be more effective with one or two nuclear submarines in large areas such as the Mediterranean; otherwise a large number of conventional submarines may be needed for a mission of similar efficiency. Considering the total cost and long construction durations of several conventional submarines, a medium-size nuclear submarine with a maximum of 1-1.5 billion dollars is thought to be both much more cost-effective and “deterrent at a game-changing level“. In addition, the submarine support of Offshore Task Force/Group’s will be more effective with nuclear submarine within the framework of the sea control and power projection strategy.

The Turkish Submarine Fleet is one of the most powerful conventional submarine fleets in the Mediterranean as can be understood from open sources.[13] In particular, it is very effective in the surrounding seas and provides high deterrence. On the other hand, nuclear submarines have a “game changer” feature in naval operations and in diplomacy. Therefore, it would be more beneficial to direct efforts towards a platform that will provide additional capabilities and also “strategic and psychological deterrence” rather than an existing submarine type. With the addition of several nuclear submarines to the existing conventional submarine fleet, the advantages of both types can be combined and superior underwater dominance can be achieved in any geography, including overseas operations. The construction of existing German designs that have proven themselves can continue if the need for conventional submarines prevails in the future. We consider that there is no marginal benefit of spending so much time and effort building a similar type of conventional submarine.

Since the design process of a submarine, whether nuclear or conventional, takes a very long time, it can be considered to obtain a ready-made design and build it in Turkey just like the case in Anatolian amphibious assault ship. In this way, approximately 10 years of time required for the design will be saved.

Consequently, it should be aimed to build nuclear-powered attack submarines that can operate in vast operational areas without any shortage of range, survival and fuel and that can attack surface and land targets with torpedoes and missiles; therefore, the nuclear powered submarine (SSN/SSGN) alternative should seriously be taken into consideration in MILDEN design.

The Turkish Submarine Fleet is one of the most powerful conventional submarine fleets in the Mediterranean.


[1] Submarine Warfare, https://fas.org/man/dod-101/sys/ship/submarine.htm

[2] Submarine snorkel, https://en.wikipedia.org/wiki/Submarine_snorkel#Operational_limitations

[3] Submarine Warfare, https://fas.org/man/dod-101/sys/ship/submarine.htm

[4] Andersson, Jan Joel (2015) “The Race to the Bottom,” s.1

[5] Guided Missile Submarine, Nuclear Powered

[6] Geoffrey Till, Sea Power, A Guide for the Twenty-First Century, s.124

[7] Patton, James H. Jr. (2005) “The Submarine as a Case Study in Transformation: Implications for Future Investment,” Naval War College Review: Vol. 58: No. 3, Article 9. s.6

[8] https://www.navyrecognition.com/index.php/naval-news/naval-news-archive/2021/june/10251-brazilian-ssn-alvaro-alberto-to-be-commissioned-in-2034.html

[9] Nuclear-Powered Ships, https://www.world-nuclear.org/information-library/non-power-nuclear-applications/transport/nuclear-powered-ships.aspx

[10] Nuclear Submarine Game Changer: New Countries To Go Atomic, https://www.forbes.com/sites/hisutton/2019/11/03/nuclear-submarine-game-changer-new-countries-to-go-atomic/#c06b6371d74b

[11] List of submarines of the Turkish Navy, https://en.wikipedia.org/wiki/List_of_submarines_of_the_Turkish_Navy

[12] Türkiye Atom Enerjisi Kurumu, Tarihçe https://www.taek.gov.tr/tr/kurumsal/services.html

[13] Submarine Fleet Strength by Country (2020), https://www.globalfirepower.com/navy-submarines.asp

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