An interesting take on India's nuclear submarine program

Since 2009 Submarine Matters has regularly provided updates on India's nuclear submarines. This goes back to the old name of this website “Australia By The Indian Ocean” (which Pete wrote around 2007 – 2011) and then increasing interest in submarines. In more recent years Ghalib Kabir (GK) has provided comments and links on these matters

Indian Ship Submersible Ballistic Nuclear (SSBN)

The sequence of Indian SSBNs goes by S numbers:

S-1 (or S1) was an onshore test nuclear reactor reliant on extensive and expensive Russian assistance.
S-2 is the indigenous INS Arihant, launched 2009, around 6,000 tons, a prototype SSBN constructed to test: 
- stealth/quieting architecture, 
- India made nuclear propulsion of the slow start-stop 83MW reactor, 
- K-15 or "K15" missiles (with a safe firing point-range only adequate to hit coastal Pakistani cities, like Karachi) and K4 (3,500 km range capable of hitting all Pakistan, central and southern-most China (eg. China’s Yulin/Hainan SSBN/SSN base, Guangzhou and Hong Kong)
- central computer processing
- combat system including sensors also to operate the 6 torpedo tubes
- command and control, and crew procedures including damage control

S-3 INS Arighat (with expected name "Aridhaman" cancelled) incorporates upgrades and refinements which would likely include improved stealth/quieting, improved quality of missile cold launch capabilities while the sub is still moving (Pete thinks the numbers of silos remain at 4 rather than less likely 8(?)) and other SSBN aspects. GK commented September 25 “The older [2011] videos of the Layner SLBM launch by Russia are clear proof imho that the K-4 Cold launch technique was taught by Russia to India.” GK commented September 25 “The S-3 should trial [in 2020] hopefully as it is just a replica [hence 4 silos?] of Arihant (S-3 Arighat launched 11/2017)”

S-4 [not launched in 2018] GK commented September 25. 2019 "I really don't know if they will be constructed. Some say, the S4 keel has been already laid and it is under construction. I am not so sure. I think the 6,000 ton Arihant and Arighat will serve as good training platforms" [Pete comments – My November 2018 report may be wrong. At just 7,000 tonnes (1,000 tonnes heavier than Arihant and Arighat) once thought future S4 or S4*’s hull diameter could not accommodate the tallness of a K-5 or K-6 missile – so S4 and S5 would only amount to high priced make-work projects for a SSBN continuous build program]

S-5 [at Wiki and at Submarine Matters] GK commented September 25, 2019 "S-5 should trial by late 2020s. [The S5 weighing 13,500 tonnes will have] K-5 or K-6 MIRV SLBMs [to] takes over as the sea leg of India's Nuclear Triad.

[Pete comment – a K-5 SLBM with a range of 5,000 km would be inadequate from a Bay of Bengal launch point to hit all of China (especially Beijing). So India’s S-5 SSBN will need to be large enough/have a sufficient diameter to fit or retrofit a taller K-6 missile with a range of 8,000 km. Also increased range to 8,000 km would provide for a safer Indian SSBN launch point south of the rather closed Bay of Bengal (a bay where Chinese SSNs and SSKs may lie in wait for Indian SSBNs). China, with its improved relations with Bangladesh, Thailand and maybe Myanmar, may also more readily be able to string fixed undersea sensors that could focus on Indian SSBNs in the Bay of Bengal). Similarly Chinese undersea sensors strung across the Indian Ocean to the Seychelles and/or Mauritius may improve China’s ability to track nuclear submarines.]

Way Ahead

CIMSEC commented "in February 2015, the Modi government accorded political approval for six SSNs." [Pete Comment - The main function of SSNs are to carry out patrols to protect SSBNs. For India this would be especially when its SSBNs are leaving the main Indian east coast naval base of Vishakhapatnam to go on deterrent patrol and re-entering Vishakhapatnam.].

Ghalib Kabir commented September 25, 2019 [Russia turned down India’s offer to lease a Yasen SSN or provide related late model SSN Yasen level help]. [Russia instead offered “Chakra-3” an Akula lease and India accepted.] "Considering the perennial French struggle with LEU [submarine] reactors and their perceived drawbacks, I think India will try to or is already possibly duplicating the [Russian] HEU 190MWt OK-650B Akula reactor for [India’s] own SSN."

[CIMSEC commented "in February 2015 "Consequently, for [India's next SSBN may be called Arindhaman], there is a clear need to upgrade the reactor. The Arihant has an 85-MWt reactor (≈17 MWe, since in a naval reactor, roughly 5 MWt = 1 MWe). The one for the larger and heavier Arindham[an] will need to be somewhere between 160-190 MWt (32-38 MWe) and this is an upgrade that is ongoing."]

GK commented September 25, 2019 "As far as [GK is] concerned, the bigger focus should be on the SSN combat suite and sonar capability, where I think India should put its experience with TKMS and DCNS [now Naval Group] to good use. Especially the low frequency cylindrical array passive sonar etc. which are useful in hunting enemy SSNs. But a fully Indian SSN is unlikely before 2035 as things stand.”

GK commented September 25, 2019 I don't think the French gave any [SLBM] missile or reactor related help. [The French] consultancy I assume (ongoing) is for non-reactor/[Exocet?] missile design aspects of subs (probably SSNs under the garb of the Scorpene project). This is conjecture at best and very likely the French 'help' way more limited than the Russians.” [Pete Comment: France's Naval Group (was DCNS) may possibly have passed on some non-nuclear details useful for SSNs as part of India's current Kalvari class Scorpene Project and maybe in the future Project 75I (for India) bid.]

Immense Thanks to -
by Ghalib Kabir , Pete Coates and CIMSEC