Once commissioned, the vessel will provide a significant boost to India’s strategic deterrent
Background
India is speeding up a navy modernisation program and leaning on its neighbours to curb Chinese submarine activity in the Indian Ocean, as nations in the region become increasingly jittery or rattled over Beijing's growing undersea prowess. David Brewster, a strategic affairs fellow at the Australian National University, said India will do everything in its power to recover its dominant position in the Indian Ocean.
Indian defence planners realized the importance of nuclear submarines and decided to build this capability indigenously. It is to the credit of the Indian Navy planners that they began designing miniature nuclear reactors in a classified group code named the "New Reactor Projects Division", carved out of BARC’s Reactor Engineering Division, with dozens of engineers as the core design team. Work under Dr RP Dastidar, head of the Reactor Group, had already begun and was code-named PRP (Propulsion Recycling Project – land Based) in the late 1970s, after the confidence gained in the Smiling Buddha Peaceful Nuclear Explosion (PNE) test on May 18, 1974.
A Real ‘Make in India’ Project
INS Arihant is India's first nuclear-powered submarine. The ship submersible ballistic, nuclear (SSBN) submarine was launched at the Indian Navy's dockyard for sea trials in Visakhapatnam in December 2104, which is the headquarters of India's Eastern Naval Command. The highly secretive project was earlier known as the advanced technology vessel (ATV). India joined an elite club of six nations (US, Russia, France, Britain, and China) that operate nuclear submarines carrying ballistic missiles.
The indigenously built submarine would be used for self defence. The name Arihant derives from two words – Ari "Enemy" and Hanth meaning "Destroy", thus meaning "Destroyer of Enemies", an apt name for one of the most important defence related projects ever undertaken in the country. Construction of five more nuclear-powered submarines are also being planned and as per reports the second and third vessels construction is progressing at a brisk pace.
The project is jointly developed by the Director General Naval Design (DGND), Indian Navy, Bhabha Atomic Research Centre (BARC), Indira Gandhi Center for Atomic Research (IGCAR) and Defence Research and Development Organisation (DRDO) at the naval dockyard in Eastern Naval Command. Apart from government agencies several private sector industries were involved in the execution of this prestigious project includes Larsen & Toubro (L&T) responsible for overall design, TATA Power, a division of TATA Group which designed the control systems, Walchandnagar Industries has designed the steam turbine. These companies are proficient heavy engineering, construction and manufacturing entities.
Arihant is undergoing extensive sea tests in the Bay of Bengal which is likely to last at least two years, it follows the usual 2 tier testing methodology undertaken by most naval powers, first harbour acceptance trials (HATs) and then followed by sea acceptance trials (SATs) wherein various components will be tested at different depths, temperatures and pressure. The submarine is going through all the safety procedures. There are several government agencies, committees and atomic bodies, and the nuclear submarine needs to undergo scrutiny at various levels. Several surface and deep sea dives have already been done. Overall, the submarine is on the right track and it will be commissioned by this year-end.
Arihant is powered by 83 MW pressurized light water reactor build by BARC using 40% enriched Uranium U-235 as fuel. It is a tremendous engineering feat to master light water miniature uranium reactors in a confined submarine space. This reactor generates tremendous heat, driving a steam turbine which drives a shaft lending power to the propellers. British science fiction writer Sir Arthur Clark, once said, “Any sufficiently advanced technology is indistinguishable from magic.” The advantage of a nuclear submarine over conventional type is that it can propel underwater for prolonged periods of time, the limitation being food supply and human endurance. Oxygen is regenerated from sea water.
Arihant design
Arihant's design is based on the Russian Akula-1 Class submarine. Basic features of Arihant is Length 110m, Beam 11m, Draft 9m, Diving Dept 300m, Crew Strength 95, Displacement 6000 tons and a Maximum speed of 24 knots submerged.
The submarine's exterior is uneven and the hull is placed on a mat covered with tiles. The tiles help in absorbing sound waves and provide stealth capability to the submarine. Compared to conventional submarines, the conning tower of Arihant is situated near the bow instead of the center The central part of the submarine's body consists of the outer hull and an inner pressurized hull. The starboard side consists of two rectangular vents that draw in water when the submarine submerges into sea.
The Indian Navy and the DRDO together designed the submarine. Once the design was finalised detailed engineering was implemented at L&T's submarine design centre using 3D modelling and product data management software.
Arihant Weapons
Arihant will be capable of carrying all types of missiles and will have underwater ballistic missile launch capability. Arihant is capable of launching nuclear-capable Submarine Launched Ballistic Missiles (SLBM). Each submarine will be equipped with 2 K-15 SLBMs that can be launched even under ice caps. The 6.3t missiles can carry a 5t nuclear warhead targeted 750km away. Ultimately, India hopes to equip them with 4 K-4 SLBM, which have ranges of up to 3,500 km. Apart from the K-15s, the submarine will carry a range of anti-ship and land-attack cruise missiles and torpedoes.
Nuclear Propulsion
Arihant's Nuclear Power Plant
A significant progress in the development of Arihant took place when the land-based pressurised water reactor became operational in 2004 at the IGCAR in Kalpakkam, near Chennai. Following this, miniaturisation of the land-based PWR had to be carried out to enable it to fit into the confined space of the submarine. The reactor consists of 13 fuel assemblies each having 348 fuel pins. Several companies supplied components for the reactor. High grade steel was supplied by Heavy Engineering Corporation, Ranchi to build the reactor vessel, the steam generator was provided by Bharat Heavy Electricals Limited (BHEL); and Audco India, Chennai built the pressure valves.
The propulsion plant housing the reactor is 42m long and 8m in diameter. The complete propulsion plant along with the primary, secondary, electrical and propulsion systems occupy half of the submarine. To reduce the weight of the plant, light water and enriched uranium is used as opposed to non-enriched uranium used in land-based reactors. The PWR consists of a huge pressure hull, a tank containing water and the reactor.
Safety
Taking lesson from the past accidents involving submarines, Indian defence scientists at DRDO have developed a health monitoring system for underwater vessels that can alert about any potential breakdown thereby averting a possible mishap. The system works on the philosophy of predictive maintenance and has been installed on the first indigenous nuclear submarine INS Arihant.
Control and communication systems
Arihant is fitted with a combination of two sonar systems – Ushus and Panchendriya. Ushus is state-of-the-art sonar meant for Kilo Class submarines. Panchendriya is a unified submarine sonar and tactical control system, which includes all types of sonar (passive, surveillance, ranging, intercept and active). It also features an underwater communications system.
Finally what INS Arihant Class ships bring to the region a credible power projection capability for the Indian navy. The Navy's Kilo class & the Type 209 submarines have limited operational capabilities. But with the additions of INS Arihant these technical limitations are no bound for the Indian navy operations in the region.
The culmination of the nuclear submarine project is a handsome tribute to the naval planners, Indian atomic scientists, designers and engineers. This is indeed a great technological leap for the nation.
