India, Commissioned the first Arihant submarine in Aug 2016, which in Sanskrit means “enemy fighter”, has become part of an elite club of countries – Russia, USA, China, France and Great Britain, which have nuclear submarines with ballistic missiles. However, the ongoing project is facing technological challenges.
Development
Scientific research on the project of creating a nuclear submarine began in the 1970s. However, due to lack of experience, technological problems and US opposition, positive results were not achieved.
A new phase began in 1998. The submarine was developed jointly by the Navy, the Bhabha Center for Atomic Research and the Defense Research and Development Organization at the Naval Shipyard in Vishakhapatnam. Russian specialists were involved in the project to create a submarine hull and a nuclear reactor. In 1998, India acquired a reactor project from Russia, and by 2004 created its own prototype. Construction of the building began in 1998, and, according to experts, it is based on the Soviet submarine K-43 of the Skat project, which India leased from the USSR in the 1980s.
Arihant was first launched in 2009. The power plant was ready by 2013, and sea trials began at the end of 2014. The official transfer of the Indian Navy submarine took place in August 2016. The first nuclear submarine INS Arihant cost the Indian government $ 2.9 billion. The second submarine of this class, INS Aridhaman, was laid in 2010, launched in 2017 and is currently undergoing testing.
Design
The length of the submarine is estimated at 111 meters, the width is 11 m, and the underwater displacement is 6500 tons. The immersion depth is classified, but there is evidence that the tests took place at a depth of 350 meters. This is the smallest ballistic missile submarine in the world, with the possible exception of the North Korean Gorae class submarine. At the same time, Arihant is the longest submarine in the Indian Navy, accommodating a crew of 95 people. It can reach speeds of 12-15 knots in the surface position and up to 24 knots in the underwater position.
Nuclear Power Plant
Arihant has an 80 MW water / water nuclear reactor. The reactor was developed by the Bhabha Atomic Research Center with the assistance of the Rubin Russian Design Bureau. The reactor consists of 13 fuel assemblies, each of which has 348 fuel pins. This is a small reactor that limits the time spent by the submarine at sea. For comparison: the Soviet submarines of the Dolphin project developed in the second half of the 1970s have a 180 MW power plant.
The power plant in which the reactor is located has a length of 42 m and a diameter of 8 m. A full power plant, along with primary, secondary, electrical and propulsion systems, occupies half the submarine. Such reactors typically maintain a service life of up to 20–25 years, depending on the quality of assembly and design.
Armament 
Currently, an Arihant class submarine can carry either 4 K-4 ballistic missiles or 12 K-15 ballistic missiles. The K-15 is a 6-ton missile with a range of up to 750 km, which gives it the ability to hit only the southern half of Pakistan. K-4 has not yet been adopted, but mass production began in 2020. The K-4 is a 17-ton missile carrying a 2-ton nuclear warhead.
In addition, the submarine is capable of carrying six 533 mm torpedoes. Torpedoes can be replaced by naval mines and cruise missiles in accordance with the specific requirements of the mission (or have a mixed combat load).
Underwater Navigation and Detection Tools
Arihant is equipped with a combination of two sonar systems: Ushus and Panchendriya. Ushus is a modern active and passive sonar. Panchendriya – a single sonar and tactical control system for a submarine, which includes all types of sonar (passive, active, observant, rangefinder and interceptor). It is also equipped with an underwater communication system.
Further development
India originally planned to build four submarines by 2020. With the completion of four nuclear boats, India can finally achieve its strategic invulnerability goal. Now, naval sources suggest that four submarines could be commissioned by 2023. In total, the Indian Navy plans to build six Arihant class submarines.
While the capabilities of the Arihant submarine do not allow India to ensure strategic parity with China. For this, India needs not only more submarines with ballistic missiles, but also longer-range missiles that could strike deep into Chinese territory.
The development of a submarine that could carry larger ballistic missiles has been underway in India since 2004. However, in 2006, during a major technical review of the program, it was concluded that, despite the actions taken, it was not possible to create a submarine equipped with long-range ballistic missiles. That is why INS Arihant received only the K-15 missile.
In 2015, India began a new stage in the creation of a submarine capable of carrying long-range missiles. The Arihant submarines currently under development should become much larger than the existing INS Arihant and INS Aridhaman in order to be equipped with new and larger K-5 and K-6 ballistic missiles with a range of 5000 and 6000 km, respectively, which are also currently under development. They will allow to strike at Chinese and Pakistani targets far beyond the Indian Ocean.
Currently, the Indian company MIDHANI is working to create a new material for the hull, which will be designed to dive to a depth significantly exceeding the existing capabilities of the Arihant class and other submarines of India. Also, for a more advanced submarine, a double-sized reactor is being developed that could withstand lengthy operations at sea. So, the first launch of the submarine INS Arihant lasted only 20 days, which indicates the shortcomings of its nuclear power plant.
Until India creates a fleet with at least six submarines with intercontinental ballistic missiles and improves the design of its nuclear power plant, its sea-based deterrent will remain a paper tiger.
The lack of experience in Indian industry can greatly delay the construction of submarines capable of carrying long-range missiles. Admiral Arun Prakash estimates that it will take 50-60 years for India to create reliable submarine containment forces. However, this does not guarantee achievement of parity with China, because while India has been creating one submarine for twenty years, China has created ten – and it is unlikely that, seeing the development of the Indian fleet, it will stand still.
Is this the type of submarine that can submerge with open hatch?