Govt Greenlights Construction of Two Indigenous Nuclear-Powered Attack Submarines (SSNs), Aiming for Six to Counter China

In a significant move to bolster its naval capabilities and counter China's growing presence in the Indo-Pacific, India has approved the construction of two indigenously designed nuclear-powered attack submarines (SSNs).

This decision, made by the Cabinet Committee on Security (CCS) chaired by Prime Minister Narendra Modi, marks a major step forward in India's quest for strategic deterrence.

The project, estimated to cost Rs 45,000 crore, will see the submarines built at the Ship Building Centre in Vishakhapatnam. This initiative is separate from the ongoing construction of five nuclear-powered ballistic missile submarines (SSBNs) of the Arihant class at the same facility. While both SSNs and SSBNs are nuclear-powered, they serve distinct roles.

SSNs are designed for offensive operations, including hunting enemy submarines and surface vessels, intelligence gathering, and supporting naval task forces. Armed with torpedoes and potentially cruise missiles, they excel in tactical warfare. SSBNs, on the other hand, are strategic assets built for nuclear deterrence, carrying and launching nuclear-armed ballistic missiles.

The need for SSNs has become increasingly critical for India, especially with China already operating six Shang class nuclear-powered attack submarines. The Indian Navy has been advocating for this project, highlighting the urgent need to address underwater capability gaps and maintain a credible deterrent against regional adversaries.

The government initially greenlit the SSN project in 2015, with design work commencing at the Submarine Design Centre in Gurgaon around 2017.

Significant progress has been made since then, including the development of a special alloy for the submarines' hulls by Mishra Dhatu Nigam, enabling them to dive deeper than the Arihant-class boats. The SSNs will also be equipped with more powerful nuclear reactors.

This development comes at a time when the lease of an Akula class nuclear attack submarine from Russia has been delayed to 2028. India's long-term plan is to induct six SSNs as part of its broader submarine development strategy.

The construction of these two indigenous SSNs is a crucial step towards achieving that goal and ensuring India's maritime security in the face of growing challenges in the Indo-Pacific region.

 

[R. Singh]

Name these SSNs Sindhughosh class ! make as many as 10 SSNs ! First SSN-INS SIndhudhvaj, 2) INS- INS -SIndhuvir, third should also be made,INS-Sindhurakshak ! Till these three launched remaining seven Kilo 's will retire !

 

[PKPRS]

So lets just import Pump jet propulsion alone and make our own design and develop.

 

[Anant]

So lets just import Pump jet propulsion alone and make our own design and develop.

Boss, I would say that while we are working on our pumpjet system, we shouldn't hold P-77 to that development. If absolutely necessary, let the first two boats be built with a conventional propeller, and by the time the next batch is green-lit (2030 or so, I'd guess), we should have a pumpjet ready to go.

 

[Olef hitler]

So lets just import Pump jet propulsion alone and make our own design and develop.

You better read the publications from DRDO (their bimonthly magazine) . They have demonstrated 535 kw rated pumpjet and can scale it upto 35MW . Also our HWT's do use pumpjet .

 

[NSR]

A great day to start with such wonderful news about very much needed Indian SSN approval.

Indian Navy must install proper sized silos to carry SLBMs with at least 7000+ kms to bring every corner of china into its sights to create a great DETERRENT against its adventurisms in future.

BARC already developed 190+ MW miniature nuclear reactor for SSN propulsion.

All in all great development and pray for its complete success.

 

[Rajesh]

Given the displacement is close to the 6,500 of Arihant, is that a sign that design uses that as a base (I've actually posted prior suggestions on how to modify SSBN to SSGN)?

 

[M S Chatterji]

Is the 185 MW nuclear reactor needed for the attack submarine ready?. That is the minimum power needed for the attack submarine.

 

[Dredd]

Is the 185 MW nuclear reactor needed for the attack submarine ready?. That is the minimum power needed for the attack submarine.

yes, a variant is already available and integrated in S4 class ssbn

 

[Anant]

Indian Navy must install proper sized silos to carry SLBMs with at least 7000+ kms to bring every corner of china into its sights to create a great DETERRENT against its adventurisms in future.

Um, minor correction: We are referring to SSNs here, so SLBMs are out of the question. That'd make these SSBNs, which, as you well know, is something we already possess and are working on.

 

[Anant]

Given the displacement is close to the 6,500 of Arihant, is that a sign that design uses that as a base (I've actually posted prior suggestions on how to modify SSBN to SSGN)?

Fairly possible that the design will remove the SLBM module, maybe slot in a smaller VLS module for SLCMs (though I think that such a module is more likely in the next batch), and optimise the design.

 

[Anant]

yes, a variant is already available and integrated in S4 class ssbn

Arihant and Arighat still have the 83 MW reactor. That said, the S4 and other boats may have an upgraded reactor. Perhaps even the 190 MW reactor. Who is to say?

 

[desigandu]

Arihant and Arighat still have the 83 MW reactor. That said, the S4 and other boats may have an upgraded reactor. Perhaps even the 190 MW reactor. Who is to say?

Are there any major changes in a reactor besides power output in an SSN vs an SSBN?
My understanding was our 83mw reactor was the constraint for SSNs due to limited power thus we needed a more powerful 190mw reactor…Now if we have the 190mw reactor it could power the 6000 ton SSNs and the S5s which are likely to be 13000tons!
Hopefully after 2030, we build a 250mw reactor that can power future SSNs on 11000 ton and SSBNs on 20000 ton and our nuclear propulsion carriers!

 

[desigandu]

Fairly possible that the design will remove the SLBM module, maybe slot in a smaller VLS module for SLCMs (though I think that such a module is more likely in the next batch), and optimise the design.

US actually converted some of its Ohio class SSBNs to 4 SSGNs carrying 22 VLS tubes of 154 tomahawks, instead of the 20 SLBMs…So going by that Arihant if converted to an SSGNs could have say 6 VLS tubes with 8-12 LRLACMs…Thoughts?

 

[desigandu]

Boss, I would say that while we are working on our pumpjet system, we shouldn't hold P-77 to that development. If absolutely necessary, let the first two boats be built with a conventional propeller, and by the time the next batch is green-lit (2030 or so, I'd guess), we should have a pumpjet ready to go.

How hard, time and costwise may be needed to change a propeller to a pump jet during a refit, overhaul that will be needed for refueling the reactor in 10 years…

 

[Sandeep]

This is a critical requirement and I’m glad permission has been given. This means that the 190MW reactor is ready and we have probably used a lot of the same technology and equipment from the Arihant class submarine which will help to reduce development time. Developing this with a 90% indigenous content is very good progress and that figure will increase in the next batch. Ideally we should aim to have at least 8-10 SSN so that we cover the Indian Ocean but also have 1-2 deployed near the South China Sea.

 

[op gupta]

I think two ssns are sufficient to map whole Indian ocean there is no need to expand the fleet to five and waste more tax payers money on these costly subs.

 

[Anant]

How hard, time and costwise may be needed to change a propeller to a pump jet during a refit, overhaul that will be needed for refueling the reactor in 10 years…

Very difficult. My understanding of pumpjets is fairly limited, but if you have remove a propeller, that may well entail massive work on the submarine, and as such, may not be worth the time or expense.

 

[sanket]

So lets just import Pump jet propulsion alone and make our own design and develop.

Ha Ha Its only French going to Help Only I was in The forum saying French can Help In Developing Bharat's Defence sectors From Military satellite, Submarine ,Fighter jet, Aero-Engine, & Now people like u are welcoming the pumpjet Tech That only French can give, Bharat can develop no doubt about that but it will take Time by the time first SSN likely to have French , & Future Foolow-on/ SSN Variant might b INtegrated with Indigenous Pump jet propulsion

 

[Anant]

US actually converted some of its Ohio class SSBNs to 4 SSGNs carrying 22 VLS tubes of 154 tomahawks, instead of the 20 SLBMs…So going by that Arihant if converted to an SSGNs could have say 6 VLS tubes with 8-12 LRLACMs…Thoughts?

More than likely. If we do end up going for three S5-class SSBNs, combined with the three enlarged Arihant-class boats, I have a feeling Arihant and Arighat may well be converted to SSGNs when they head in for their mid-life refits in the late 2030s and early 2040s.

Regarding the Ohio-class, the first few boats were built with 24 SLBM tubes, and these were then modified on the first four boats. Essentially, what they did was to put in a cage of sorts inside 22 of the SLBM tubes, with each tube then being capable of carrying 7 Tomahawk SLCMs. The last two tubes were retained as is to be used for special operations. The Trident Is had a diameter of 1.8 metres, and were launched from tubes with a diameter of 2.2 metres. The Tomahawk, on the other hand, has a diameter of around 0.52 metres, which allows for a hexagonal layout with the seventh missile in the middle.

Coming to Arihant and Arighat, the K4 SLBM is supposed to have a 1.3 metre diameter, compared to the K-15 at 0.74 metres and Nirbhay at 0.52 metres. That leads me to believe that we can theoretically fit in five Nirbhays into a K-4 tube. That, therefore, means a total of 20 SLCMs per submarine, assuming the LR-LACM doesn't end up being wider than the Nirbhay.

The exact number would depend on the size of the SLBM tubes on the Arihant-class, and the allowance one would have to build for such a cage to hold the SLCMs. For instance, if I assume the SLBM tubes have a diameter of 1.5 metres, and I assume the SLCM tubes to have a diameter of 0.55 metres each (including the cage allowance), then you can fit in 5 missiles. If I increase that SLCM tube diameter to 0.6 meters, the number of missiles comes down to 4. It depends on the exact measurements.

 

[Anant]

Are there any major changes in a reactor besides power output in an SSN vs an SSBN?
My understanding was our 83mw reactor was the constraint for SSNs due to limited power thus we needed a more powerful 190mw reactor…Now if we have the 190mw reactor it could power the 6000 ton SSNs and the S5s which are likely to be 13000tons!
Hopefully after 2030, we build a 250mw reactor that can power future SSNs on 11000 ton and SSBNs on 20000 ton and our nuclear propulsion carriers!

I have a feeling that the 190 MW reactor may either be ready, or the first 2 SSNs may have an upgarded variant of the older 83 MW reactor, with follow-on ships going for the 190 MW reactor. If the latter is the case, then I wouldn't be surprised to see S4 and S4* carrying the same upgraded reactor, with the fifth boat potentially carrying the 190 MW reactor.

 

[desigandu]

Very difficult. My understanding of pumpjets is fairly limited, but if you have remove a propeller, that may well entail massive work on the submarine, and as such, may not be worth the time or expense.

Thanks…How big a deal is a pump jet in terms of noise vs a propeller…I agree if a pump jets causes delay that takes the SSNs beyond 2035 delivery, then the first 2 boats should go with propellers. But in the event the french can really help, then let us use their pump jet for the first 2 before we get our own design for the rest 2…
Nevertheless after the 1st 4 SSNs we need to go for a larger 10000 ton SSN with 250mw reactors, Large VLS capability and 8-12 boats starting 2045…

 

[Anant]

Thanks…How big a deal is a pump jet in terms of noise vs a propeller…I agree if a pump jets causes delay that takes the SSNs beyond 2035 delivery, then the first 2 boats should go with propellers. But in the event the french can really help, then let us use their pump jet for the first 2 before we get our own design for the rest 2…
Nevertheless after the 1st 4 SSNs we need to go for a larger 10000 ton SSN with 250mw reactors, Large VLS capability and 8-12 boats starting 2045…

Pumpjets are quieter since they mostly eliminate cavitation. Moreover, they tend to be more efficient at high speeds, where a conventional propeller would be more noisy due to cavitation and would be slowed down by the vertices generated by rotating at higher speeds.

On the other hand, pumpjets are more expensive, difficult to design, operate, and maintain. They are also heavier than a conventional propeller and require more energy. The increased weight makes it unsuitable for smaller submarines (thanks to weight distribution), and the increased power requirements makes it difficult to justify pumpjets on a diesel-electric boat.

In fact, the only diesel-electric boat that I know of with a pumpjet is the Alrosa, a Kilo-class submarine of the Russian Navy. She was fitted with an experimental pumpjet as an experiment to see if these could be incorporated on other SSKs. It was found that this wasn't worthwhile, and it is speculated that even Alrosa has since been converted back to a propeller setup.