INS Arihant is to be the first of the expected five in the class of submarines designed and constructed as a part of the Indian Navy's secretive Advanced Technology Vessel project. The Arihant-class submarines are reported to be based on the. Their crew will have the opportunity to train on INS Chakra, an Akula-class submarine, which the Indian Navy leased from Russia. Arihant will be more of "a technology demonstrator", rather than a fully operational SSBN according to Admiral Nirmal Verma. The vessel will be powered by an 83 MW pressurised light-water reactor with enriched uranium fuel. A land-based prototype of the reactor was first built at Kalpakkam and made operational in September 2006. Successful operation over a period of three years yielded the data that enabled the production version for Arihant. It was reported that an 80 MW nuclear reactor was integrated into the hull of the ATV in January 2008. The hull for the vessel was built by L&T's Hazira shipbuilding facility. Tata Power Strategic Engineering Division built the control systems for the submarine. The systems for the steam turbine integrated with the reactor are supplied by Walchandnagar Industries. The consultancy for this project was provided by Russia. Russia was also reported to have provided assistance to Bhabha Atomic Research Centre scientists in miniaturising the reactor to fit into the hull of the nuclear submarine
Armament
Arihant has four vertical launch tubes, which can carry 12 smaller K-15 missiles or four larger K-4 missiles. The K-4 has a longer range of and has commenced trials.
Launch
INS Arihant was introduced to the public on 26 July 2009 at a symbolic launch ceremony by Prime Minister Manmohan Singh's wife Gursharan Kaur. The launch coincided with the 10th anniversary of the conclusion of the Kargil War. and consisted of floating the vessel by flooding the dry dock. Defence Professionals Daily claimed Arihant was launched without key systems including its nuclear reactor, surveillance equipment, and ordnance. Per naval tradition, Gursharan Kaur cracked a coconut on the hull to mark the launch of the submarine at the secret naval base in Visakhapatnam. Photography was prohibited and photos showing the complete vessel are not available. In his address to the crowd, Prime Minister Singh billed the submarine as an outcome of a public-private partnership. He also thanked Russia in his address, stating, "I would also like to express our appreciation to our Russian friends for their consistent and invaluable cooperation, which symbolises the close strategic partnership that we enjoy with Russia". The launch of Arihant strengthens India's endeavour to build a credible nuclear triad – the capability to fire nuclear weapons from air, land and sea.
Development phases
On the condition of anonymity, a nuclear scientist familiar with the project echoed this report in response to the media coverage that India had successfully launched a completed nuclear submarine. It was also expected that the duplication of India's land based reactor, integration of systems, and sea trials are expected to take three to five years. Admiral Verma told reporters on 7 August 2012 that sea trials of Arihant are commencing in coming months and she is steadily progressing towards operationalisation. On 27 January 2013, Sagarika, the primary armament of Arihant, completed its final developmental test and was later integrated with the submarine. On 10 August 2013, the nuclear reactor of the submarine went critical; this was done after several months of system checks using shore-based high-pressure steam. The reactor's power was raised in increments of 5 to 10% until it reached full power.
Sea and weapons trials
On 13 December 2014, Arihant sailed north along the Bay of Bengal coast off for its extensive sea trials. The sea trials included the firing of the indigenous submarine-launched Sagarika ballistic missile. On 25 November 2015, a dummy or unarmed Sagarika missile was successfully test fired from Arihant. The submarine then underwent further extensive sea trials, which were completed by early February 2016. Though it had initially been expected Arihant would be commissioned in time to participate in the International Fleet Review 2016, her participation was subsequently ruled out due to security concerns. On 23 February, Arihant was officially confirmed as ready for operations. According to The Economic Times, several weapons trials of INS Arihant have been undertaken secretly.
Operational history
In August 2016, Prime Minister Narendra Modi commissioned INS Arihant into the Indian Navy. In January 2018, it was reported that "human error" during maintence on the Arihant in 2017 lead to saltwater flooding the propulsion area while the submarine was docked, rendering it inoperative for ten months while pipes were replaced.
First deterrence patrol
It was announced on 5 November 2018 that INS Arihant had completed its first deterrent patrol. The 20 day long patrol ended on 4 November 2018. PM Narendra Modi felicitated the crew of Arihant after the patrol. This marked the completion of India's nuclear triad.
