Project 75 A Class Submarines

[haldilal]

India’s Rs 1.2 lakh crore nuclear submarine project closer to realisation

Nuclear attack submarines will give India a significant strike and area denial capability in the region.

economictimes.indiatimes.com

 

[fire starter]

 

[sameer]

This is an old but a very informative thread that I bookmarked and it summarizes what reactor tech is currently under development and some general SSN info.

It's highly likely that we will go with CLWR-B2 reactor for our indigenous SSN. This reactor is currently under development from BARC. This is also the reason why we're leasing INS Chakra III from Russia. The reactor on Chakra 3 has a similar power output and will help our sailors learn the ropes before transitioning to indigenous SSN's.

 

[Pundit Pikachu]

The Indian Navy is actively pursuing the acquisition of advanced nuclear-powered attack submarines (SSNs) through Project 75 Alpha. Although the project was initiated in 2015, it is still in its early stages, and actual construction is not expected to commence before 2032.

There is a lot of speculation surrounding who will be the developmental partner, will we go independently or will we collaborate, what would be the SSN look like, what weapons it could carry & what capabilities it might possess.
India currently has two choices either opt for a fully indigenous approach, with technical assistance from the Russians or Alternatively, develop the submarines in collaboration with the french based on their Barracuda-class SSN with an indian reactor.
However it is most likely that India will opt for the first choice with P75A being designed by the Naval Design Bureau with some technical assistance from Russia

The most important component of a nuclear-powered submarine is undoubtedly its nuclear reactor, You don't design a reactor to fit into a submarine. You design a submarine to fit around the reactor.
India currently has 2 Naval Nuclear reactors CLWR-B1 and CLWR-B2
CLWR-B1: This reactor powers the Arihant-class SSBNs. It generates approximately 83 megawatts thermal (mwT) using 40% enriched uranium and is based on the Soviet VM-4 reactor of Charlie-class SSGN that India leased between 1988-91

CLWR-B2: This reactor will powers the upcoming S5-class SSBNs. It will generate approximately 190 megawatts thermal (mwT) and is most likely based on the Soviet OK-650B reactor of Akula-class SSGN that India leased between 2011-21


Now lets consider a CLWR-B1 based design first
A B1 based design would be the most affordable & quickest way to get SSNs in hand as it would be an improved Arihant class without the Silos, and a similar beam (diameter) but shorter length with a smaller displacement of around 5000 tons (due to the lack of Silos)
Since it would be very similar in design to the current Arihant class SSBNs it would pretty much allow all existing upstream suppliers & companies to be carried forward and existing production line to be easily repurposed cutting down on both time & money required to get the boats in the water.

However this approach also has a lot of problems, first and foremost the CLWR-B1 reactor technology itself is very old (its a gen II+ reactor) and is thus relatively quite noisy, although technologies such as Nuclear Electric Propulsion can offset this disadvantage to a certain extent by making the submarine quiter, it is unlikely that it would be enough, not to mention it was never intended for a hunter-killer role to begin with (as it was a designed for an SSBN) and would be at a serious power disadvantage against its chinese rivals.
For reference a French Barracuda class which only displaces 5300 tons (submerged) has a 150 MwT reactor, a 90 MwT CLWR-B1 will never be able to provide adequate power to a 5000 tons Arihant based SSN.
Thus in my opinion a B1 based design is very very unlikely

Now coming to a CLWR-B2 based design,
The B2 based design would require an almost complete overhaul of infrastructure and would essentially be a new design with little in common with what we have built so far, We will need to train a fresh crop of engineers on this reactor type, re-tool our infrastructure & re-design critical components of submarine hull, however since we are already doing all that anyways for the upcoming S5 class of SSBNs by leasing K-152 Nerpa (Akula Class SSN) it should not be a problem.
It would be fair to assume that a B2 based design will be heavily inspired by the Akula and S5 class.

Although the CLWR-B2 based design may not be the most cost-effective or timeline-friendly option, it offers unparalleled capabilities. If the Akula's noise-reduction techniques are adapted into this desgin (very likely) the resulting submarines could very much be as silent as the most modern SSNs of PLAN today.
This, combined with the Pumpjet propulsion (that DRDO is currently working on) would result in a truely silent boat that could very well surpass the Yasen class and hopefully begin to approach Barracuda levels of stealth.
Also, given that the future S5 class SSBN would share timelines with the SSN program, a very strong case can be made that a common CLWR-B2 reactor for both the SSN & SSBN makes a lot of sense
Thus in my opinion Indian Navy is most likely to opt for the CLWR-B2 based design


View: https://x.com/ang3lkenny/status/1680974158619086848

View: https://x.com/strategicfront/status/1320175768438190080

Preliminary Configuration of Indian SSN

View: https://x.com/strategicfront/status/1320175768438190080

 

[Pundit Pikachu]

The Indian Navy is actively pursuing the acquisition of advanced nuclear-powered attack submarines (SSNs) through Project 75 Alpha. Although the project was initiated in 2015, it is still in its early stages, and actual construction is not expected to commence before 2032.

There is a lot of speculation surrounding who will be the developmental partner, will we go independently or will we collaborate, what would be the SSN look like, what weapons it could carry & what capabilities it might possess.
India currently has two choices either opt for a fully indigenous approach, with technical assistance from the Russians or Alternatively, develop the submarines in collaboration with the french based on their Barracuda-class SSN with an indian reactor.
However it is most likely that India will opt for the first choice with P75A being designed by the Naval Design Bureau with some technical assistance from Russia

The most important component of a nuclear-powered submarine is undoubtedly its nuclear reactor, You don't design a reactor to fit into a submarine. You design a submarine to fit around the reactor.
India currently has 2 Naval Nuclear reactors CLWR-B1 and CLWR-B2
CLWR-B1: This reactor powers the Arihant-class SSBNs. It generates approximately 83 megawatts thermal (mwT) using 40% enriched uranium and is based on the Soviet VM-4 reactor of Charlie-class SSGN that India leased between 1988-91

CLWR-B2: This reactor will powers the upcoming S5-class SSBNs. It will generate approximately 190 megawatts thermal (mwT) and is most likely based on the Soviet OK-650B reactor of Akula-class SSGN that India leased between 2011-21


Now lets consider a CLWR-B1 based design first
A B1 based design would be the most affordable & quickest way to get SSNs in hand as it would be an improved Arihant class without the Silos, and a similar beam (diameter) but shorter length with a smaller displacement of around 5000 tons (due to the lack of Silos)
Since it would be very similar in design to the current Arihant class SSBNs it would pretty much allow all existing upstream suppliers & companies to be carried forward and existing production line to be easily repurposed cutting down on both time & money required to get the boats in the water.

However this approach also has a lot of problems, first and foremost the CLWR-B1 reactor technology itself is very old (its a gen II+ reactor) and is thus relatively quite noisy, although technologies such as Nuclear Electric Propulsion can offset this disadvantage to a certain extent by making the submarine quiter, it is unlikely that it would be enough, not to mention it was never intended for a hunter-killer role to begin with (as it was a designed for an SSBN) and would be at a serious power disadvantage against its chinese rivals.
For reference a French Barracuda class which only displaces 5300 tons (submerged) has a 150 MwT reactor, a 90 MwT CLWR-B1 will never be able to provide adequate power to a 5000 tons Arihant based SSN.
Thus in my opinion a B1 based design is very very unlikely

Now coming to a CLWR-B2 based design,
The B2 based design would require an almost complete overhaul of infrastructure and would essentially be a new design with little in common with what we have built so far, We will need to train a fresh crop of engineers on this reactor type, re-tool our infrastructure & re-design critical components of submarine hull, however since we are already doing all that anyways for the upcoming S5 class of SSBNs by leasing K-152 Nerpa (Akula Class SSN) it should not be a problem.
It would be fair to assume that a B2 based design will be heavily inspired by the Akula and S5 class.

Although the CLWR-B2 based design may not be the most cost-effective or timeline-friendly option, it offers unparalleled capabilities. If the Akula's noise-reduction techniques are adapted into this desgin (very likely) the resulting submarines could very much be as silent as the most modern SSNs of PLAN today.
This, combined with the Pumpjet propulsion (that DRDO is currently working on) would result in a truely silent boat that could very well surpass the Yasen class and hopefully begin to approach Barracuda levels of stealth.
Also, given that the future S5 class SSBN would share timelines with the SSN program, a very strong case can be made that a common CLWR-B2 reactor for both the SSN & SSBN makes a lot of sense
Thus in my opinion Indian Navy is most likely to opt for the CLWR-B2 based design


View: https://x.com/ang3lkenny/status/1680974158619086848

View: https://x.com/strategicfront/status/1320175768438190080

Preliminary Configuration of Indian SSN

View: https://x.com/strategicfront/status/1320175768438190080

Personal Opinion

Based on images, random bits and pieces of Information and a healthy dose of assumptions, I believe the general characteristics will be :

• A displacement of somewhere around 6000 ± 500 tons (most likely 6500 tons) (similar to Chinese Type 093B, British Astute class, or American Virginia Class)

• Most probably 4-6 VLS tubes and 6-8 533mm torpedo tubes (most likely 6 tubes, given literally all subs of Indian Navy have 6 or more torpedo tubes)
The reason P75-A will have VLS is because Indian navy was insisting for P75-I's to have them and since that plan is now down the drain it makes sense to incorporate that capability into our SSN's

• Powered by a 190MWt CLWR-B2 reactor (which is based on soviet OK-650B reactor) because the CLWR-B1 can't be up-rated any further and in its current form it would be quite underpowered for a SSN

• Propelled by a 35MW pumpjet propulsor, which is currently under development by DRDO (since S5 is not going to be propelled by a Pumpjet as evident from various hydrodynamic models of S5 class only P75-A remains the likely contender)

• House a bigger and more powerful variant of USHUS-2 Sonar

• Still unsure about the towed array sonar, But Ideally it should be an indigenous one

 

[Pundit Pikachu]

The Indian Navy is actively pursuing the acquisition of advanced nuclear-powered attack submarines (SSNs) through Project 75 Alpha. Although the project was initiated in 2015, it is still in its early stages, and actual construction is not expected to commence before 2032.

There is a lot of speculation surrounding who will be the developmental partner, will we go independently or will we collaborate, what would be the SSN look like, what weapons it could carry & what capabilities it might possess.
India currently has two choices either opt for a fully indigenous approach, with technical assistance from the Russians or Alternatively, develop the submarines in collaboration with the french based on their Barracuda-class SSN with an indian reactor.
However it is most likely that India will opt for the first choice with P75A being designed by the Naval Design Bureau with some technical assistance from Russia

The most important component of a nuclear-powered submarine is undoubtedly its nuclear reactor, You don't design a reactor to fit into a submarine. You design a submarine to fit around the reactor.
India currently has 2 Naval Nuclear reactors CLWR-B1 and CLWR-B2
CLWR-B1: This reactor powers the Arihant-class SSBNs. It generates approximately 83 megawatts thermal (mwT) using 40% enriched uranium and is based on the Soviet VM-4 reactor of Charlie-class SSGN that India leased between 1988-91

CLWR-B2: This reactor will powers the upcoming S5-class SSBNs. It will generate approximately 190 megawatts thermal (mwT) and is most likely based on the Soviet OK-650B reactor of Akula-class SSGN that India leased between 2011-21


Now lets consider a CLWR-B1 based design first
A B1 based design would be the most affordable & quickest way to get SSNs in hand as it would be an improved Arihant class without the Silos, and a similar beam (diameter) but shorter length with a smaller displacement of around 5000 tons (due to the lack of Silos)
Since it would be very similar in design to the current Arihant class SSBNs it would pretty much allow all existing upstream suppliers & companies to be carried forward and existing production line to be easily repurposed cutting down on both time & money required to get the boats in the water.

However this approach also has a lot of problems, first and foremost the CLWR-B1 reactor technology itself is very old (its a gen II+ reactor) and is thus relatively quite noisy, although technologies such as Nuclear Electric Propulsion can offset this disadvantage to a certain extent by making the submarine quiter, it is unlikely that it would be enough, not to mention it was never intended for a hunter-killer role to begin with (as it was a designed for an SSBN) and would be at a serious power disadvantage against its chinese rivals.
For reference a French Barracuda class which only displaces 5300 tons (submerged) has a 150 MwT reactor, a 90 MwT CLWR-B1 will never be able to provide adequate power to a 5000 tons Arihant based SSN.
Thus in my opinion a B1 based design is very very unlikely

Now coming to a CLWR-B2 based design,
The B2 based design would require an almost complete overhaul of infrastructure and would essentially be a new design with little in common with what we have built so far, We will need to train a fresh crop of engineers on this reactor type, re-tool our infrastructure & re-design critical components of submarine hull, however since we are already doing all that anyways for the upcoming S5 class of SSBNs by leasing K-152 Nerpa (Akula Class SSN) it should not be a problem.
It would be fair to assume that a B2 based design will be heavily inspired by the Akula and S5 class.

Although the CLWR-B2 based design may not be the most cost-effective or timeline-friendly option, it offers unparalleled capabilities. If the Akula's noise-reduction techniques are adapted into this desgin (very likely) the resulting submarines could very much be as silent as the most modern SSNs of PLAN today.
This, combined with the Pumpjet propulsion (that DRDO is currently working on) would result in a truely silent boat that could very well surpass the Yasen class and hopefully begin to approach Barracuda levels of stealth.
Also, given that the future S5 class SSBN would share timelines with the SSN program, a very strong case can be made that a common CLWR-B2 reactor for both the SSN & SSBN makes a lot of sense
Thus in my opinion Indian Navy is most likely to opt for the CLWR-B2 based design


View: https://x.com/ang3lkenny/status/1680974158619086848

View: https://x.com/strategicfront/status/1320175768438190080

Preliminary Configuration of Indian SSN

View: https://x.com/strategicfront/status/1320175768438190080

I messed up and posted the same link twice, Can somebody replace the last Twitter link with this one


View: https://x.com/GODOFPARADOXES/status/1676229235239731202

 

[Abhijeet]

The Indian Navy is actively pursuing the acquisition of advanced nuclear-powered attack submarines (SSNs) through Project 75 Alpha. Although the project was initiated in 2015, it is still in its early stages, and actual construction is not expected to commence before 2032.

There is a lot of speculation surrounding who will be the developmental partner, will we go independently or will we collaborate, what would be the SSN look like, what weapons it could carry & what capabilities it might possess.
India currently has two choices either opt for a fully indigenous approach, with technical assistance from the Russians or Alternatively, develop the submarines in collaboration with the french based on their Barracuda-class SSN with an indian reactor.
However it is most likely that India will opt for the first choice with P75A being designed by the Naval Design Bureau with some technical assistance from Russia

The most important component of a nuclear-powered submarine is undoubtedly its nuclear reactor, You don't design a reactor to fit into a submarine. You design a submarine to fit around the reactor.
India currently has 2 Naval Nuclear reactors CLWR-B1 and CLWR-B2
CLWR-B1: This reactor powers the Arihant-class SSBNs. It generates approximately 83 megawatts thermal (mwT) using 40% enriched uranium and is based on the Soviet VM-4 reactor of Charlie-class SSGN that India leased between 1988-91

CLWR-B2: This reactor will powers the upcoming S5-class SSBNs. It will generate approximately 190 megawatts thermal (mwT) and is most likely based on the Soviet OK-650B reactor of Akula-class SSGN that India leased between 2011-21


Now lets consider a CLWR-B1 based design first
A B1 based design would be the most affordable & quickest way to get SSNs in hand as it would be an improved Arihant class without the Silos, and a similar beam (diameter) but shorter length with a smaller displacement of around 5000 tons (due to the lack of Silos)
Since it would be very similar in design to the current Arihant class SSBNs it would pretty much allow all existing upstream suppliers & companies to be carried forward and existing production line to be easily repurposed cutting down on both time & money required to get the boats in the water.

However this approach also has a lot of problems, first and foremost the CLWR-B1 reactor technology itself is very old (its a gen II+ reactor) and is thus relatively quite noisy, although technologies such as Nuclear Electric Propulsion can offset this disadvantage to a certain extent by making the submarine quiter, it is unlikely that it would be enough, not to mention it was never intended for a hunter-killer role to begin with (as it was a designed for an SSBN) and would be at a serious power disadvantage against its chinese rivals.
For reference a French Barracuda class which only displaces 5300 tons (submerged) has a 150 MwT reactor, a 90 MwT CLWR-B1 will never be able to provide adequate power to a 5000 tons Arihant based SSN.
Thus in my opinion a B1 based design is very very unlikely

Now coming to a CLWR-B2 based design,
The B2 based design would require an almost complete overhaul of infrastructure and would essentially be a new design with little in common with what we have built so far, We will need to train a fresh crop of engineers on this reactor type, re-tool our infrastructure & re-design critical components of submarine hull, however since we are already doing all that anyways for the upcoming S5 class of SSBNs by leasing K-152 Nerpa (Akula Class SSN) it should not be a problem.
It would be fair to assume that a B2 based design will be heavily inspired by the Akula and S5 class.

Although the CLWR-B2 based design may not be the most cost-effective or timeline-friendly option, it offers unparalleled capabilities. If the Akula's noise-reduction techniques are adapted into this desgin (very likely) the resulting submarines could very much be as silent as the most modern SSNs of PLAN today.
This, combined with the Pumpjet propulsion (that DRDO is currently working on) would result in a truely silent boat that could very well surpass the Yasen class and hopefully begin to approach Barracuda levels of stealth.
Also, given that the future S5 class SSBN would share timelines with the SSN program, a very strong case can be made that a common CLWR-B2 reactor for both the SSN & SSBN makes a lot of sense
Thus in my opinion Indian Navy is most likely to opt for the CLWR-B2 based design


View: https://x.com/ang3lkenny/status/1680974158619086848

View: https://x.com/strategicfront/status/1320175768438190080

Preliminary Configuration of Indian SSN

View: https://x.com/strategicfront/status/1320175768438190080

Is it possible to increase the generating capacity of CLWR B2 from 190 MW to 210 MW similar to the one used in Virginia class submarines with 30 MW pump jet propulsion system?

S9G reactor - Wikipedia

en.wikipedia.org

 

[Abhijeet]

Latest on Indigenous Nuclear attack submarines

The initial case was for six such 6,000-tonne ‘hunter-killer submarines (called SSNs) under ‘Project-77’ at the SBC.

But it was whittled down and now stands at two vessels. It will take a decade to build the first two SSNs, which will be around 95% indigenous, while the next four will be approved at a later stage, the source said.

India 'fully ready' to add to fleet 2nd sub with N-tipped missiles | India News - Times of India

India News: India was set to commission its second nuclear-powered submarine, INS Arighat, armed with nuclear missiles, strengthening its strategic deterrence. Co

timesofindia.indiatimes.com

 

[Gandaberunda]

Navy is taking it’s sweet time in submarines. Only dept where navy lags is submarines and decades wasted in just finalising what they exactly needed and they are least bothered instead they’re busy in getting approval for nuclear carrier.

 

[jaijaganath]

Navy is taking it’s sweet time in submarines. Only dept where navy lags is submarines and decades wasted in just finalising what they exactly needed and they are least bothered instead they’re busy in getting approval for nuclear carrier.

Naah
Nuke subs is the only part we are progressing well wrt complexity and capabilities
We understate our capabilities in this segment
This commissioning(arighat) is merely for name sake it has been conducting combat missions just like arihant as it was also performing missions before 2017
Infact S4 has been in sea trails for long and obviously sea trails don't last that long
Infact S4* has been in sea trails since last year sept if I remember correctly
Maybe few months here and there ig
S5 working is going on but no idea about status

 

[Gandaberunda]

Naah
Nuke subs is the only part we are progressing well wrt complexity and capabilities
We understate our capabilities in this segment
This commissioning(arighat) is merely for name sake it has been conducting combat missions just like arihant as it was also performing missions before 2017
Infact S4 has been in sea trails for long and obviously sea trails don't last that long
Infact S4* has been in sea trails since last year sept if I remember correctly
Maybe few months here and there ig
S5 working is going on but no idea about status

I was mentioning about SSK and SSN not SSBN. Arihant was meant to be SSN but later converted to SSBN for nuclear second strike capability which took off timely hence Arihant isn’t considered true SSBN but became tech demonstration and SSBNs aren’t used even if war brokes out will be only used in MAD to nuke in retaliation. we still lack Submarine building capacity (Remember Russians helped in miniature nuclear reactors for our SSBNs - Akula was leased for 3billion because of that) with shoddy planning (scorpene) and P75 program dragging for more than 2 decades. Navy wants shiny toy which is nuclear carrier and wasted time dragging the feet in submarine programme

 

[jaijaganath]

I was mentioning about SSK and SSN not SSBN. Arihant was meant to be SSN but later converted to SSBN for nuclear second strike capability which took off timely hence Arihant isn’t considered true SSBN but became tech demonstration and SSBNs aren’t used even if war brokes out will be only used in MAD to nuke in retaliation. we still lack Submarine building capacity (Remember Russians helped in miniature nuclear reactors for our SSBNs - Akula was leased for 3billion because of that) with shoddy planning (scorpene) and P75 program dragging for more than 2 decades. Navy wants shiny toy which is nuclear carrier and wasted time dragging the feet in submarine programme

I haven't read anywhere arihant was designed to be ssn
Afaik it was designed to be small ssbn
That's why even a paper released in 90s if I remember had mentioned the vls for BM
Yeah it's small not proper ssbn infact in future we can convert it to ssgn with more no of CM

 

[125mm_Smoothbore]

Is it possible to increase the generating capacity of CLWR B2 from 190 MW to 210 MW similar to the one used in Virginia class submarines with 30 MW pump jet propulsion system?

S9G reactor - Wikipedia

en.wikipedia.org

chill brooo first of all most guesses on x reports 120-180Mw capasity which would be apt for 20Mw turbine (2 probably) whic would be apt for 5500-6000 tonnage designs vs 7800 tonnes vigenia class

 

[Gessler]

CCS cleared acquisition of first 2 SSNs.


View: https://x.com/ajitkdubey/status/1844050994306723914?t=-qBbOT_ubc2ctviMQcqVsQ&s=19

https://aninews.in/news/national/general-news/india-clears-mega-deals-worth-rs-80000-crore-for-nuclear-submarines-predator-drones20241009213437/

Might want to go through my old thread about the possible ways we might go down for our SSN program:


View: https://x.com/Parthu_Potluri/status/1444631861502767109?t=zp5rLn5o1bkYBqcGKj4cfw&s=19

And a thread with some fresh thoughts given what we know now:


View: https://x.com/Parthu_Potluri/status/1844080705002938513?t=VW9Kq_LmNJseQ0hCWADDqg&s=19

 

[SlayingHell]

I took another look and realized that fast attack submarines (SSNs) generally have speeds around 35 knots, which makes me think our 80 MW reactor might not be sufficient. So, either both my guess and that guy Parthu's guess about us using an 80 MW reactor are wrong, or we might end up using the 190 MW reactor to achieve the required speed. Another point is that I read the Arihant-class submarine's max speed is 25 knots, and I always felt that wasn’t fast enough for an SSN since I assumed the standard was around 35 knots.

However, like how the F-22 set an extremely high bar for supercruise, 35 knots might not be the actual standard for submarines. Some reports suggest the Astute-class, which is more advanced than the Virginia-class, has a top speed of only 30 knots. Others even claim that the Virginia-class tops out at 25 knots because they prioritized stealth and cost-effectiveness. It seems speeds beyond 30 knots may not be practical in battle scenarios, and maintaining stealth at those higher speeds could become incredibly expensive, like with the Seawolf-class.

So, what direction will the Navy take? Will they go with the 80 MW reactor, which is already in use in the Arihant, and settle for around 25 knots? As far as I know, unless the submarine's tonnage is reduced to 3,000-4,000 tons, achieving higher speeds will be tough. Or will the 190 MW reactor be ready in time?