Indian Nuclear Attack Submarine (Project 77) - Updates & Discussions

[Kitsune]

Strange naming. It says the BSMR is a "heavy" water reactor, but the acronym is PWR. PWR is traditionally used for light water reactor. Also, traditionally PHWR uses natural Uranium & PWR uses SEU. Previously in BARC newsletter they stated that they are working on SMRs of 20-200 MWe. Here they are clearly saying that SMR is based on LWR tech.
View attachment 51685
So, most evidence points to BSMR-200 being a PWR/LWR type reactor. Maybe the word "heavy" in parliamentary reply is a typo.

I think I got it figured out
There are 4 types of SMR in the works

1. BSR 220 - 220MWe PHWR using Natural Uranium, Basically a Repackaged IPWHR 220
This one is farthest along the line

https://www.pib.gov.in/PressReleasePage.aspx?PRID=2089048

RFP from NPCIL attached below
Source -

https://www.npcil.nic.in/WriteReadData/userfiles/file/Corrigendum_VIII_06012025_01.pdf

https://www.npcil.nic.in/WriteReadData/userfiles/file/Corrigendum_VII_29092025_01.pdf

2. BSMR 200 - 200 MWe PWR pressurized water reactor using Slightly Enriched Uranium, A totally Brand New Design
***Maybe some connection to S5 and P77 SSN reactor but I am not sure***
This is under R&D right now and funds were only released recently

https://www.pib.gov.in/PressReleasePage.aspx?PRID=2198337

3. SMR 55 - 55 MWe reactor of unknown type (most probably PWR)
Totally Brand New Design, Under R&D as of now and most probably in even more nascent stages than even BSMR 200

4. A 5 MWth High Temperature Gas cooled Reactor for Hydrogen Generation
Totally Brand New Design, Under R&D as of now and most probably in very nascent stages

 

[Photon Vish]

Playing around with AI image generation using ChatGPT-5.5 to try and visualize the Project-77 SSN. Here's the WIP result:

View attachment 51783

This is done keeping in mind the latest Sandeep Unnithan report which confirmed the ~10,000T displacement and inclusion of VLS.

====

I started off with this side-on drawing of a Project-885M Yasen-M sourced from the web. The 885M is somewhat similarly sized to our boat (and may have some design influence carried over as well, with emphasis on the may):

View attachment 51784

The only modification I requested at this point was the inclusion of a pumpjet (which is a possibility for P-77, though not yet officially confirmed). That gave me this output originally:

View attachment 51785

View attachment 51786

I then asked all the masts to be removed (representing them in their retracted position) and also added an X-form rudder (again, there's no official indication of P-77 having an X-rudder, I just added it because that's how most new SSNs are turning out at least in the West & also China's Type-095), which ultimately gave me the result you see at the top of this post.

I tried my best to get GPT to change the number of VLS cells from 8 to 12 (but occupying the same amount of space as before) but the outputs were all wrong. Tried Gemini but it can't seem to grasp it either. Maybe my prompt-engineering skills are just trash.

So the VLS compartment remains with 8 hatches, just like on the Yasen for now. Anyone else is free to give it a try if they can speak to AI better than I could.

The next steps would be to try and get it to bring the torpedo tubes closer to the front of the bow (as P77 would most likely have a conformal bow array like on the Astute, and not a spherical array like on Yasen. Judging from the fact we've seen R&D being conducted on CBAs, but nothing on spherical arrays). Oh, and get it to show the diveplanes as well. Will share the updated results if they're any good.

Unfortunately, official graphics of the P77 or S5 may never really appear due to GOI's weird secrecy apprehensions, so we have to settle for these fan-made creations as a visualization tool. Too bad.

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

 

[batman]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

I don't think having a 10k ton vs 6k ton submarine is gonna make that much difference in maneuverability anyway, but having a larger nuclear reactor will help us gain unmatched speed and endurance which is a much more important requirement for missions than maneuverability I believe, also heard it may incorporate X shaped rudder for better maneuverability.

US/UK/Russian/Chinese large SSNs/SSGNs (e.g., Virginia ~10k tons, Ohio SSGN conversions, Type 093/095) successfully balance this. A "very small" SSN sacrifices payload, endurance, and versatility.

Hybrid capability adds strategic flexibility (e.g., long-range strikes from stealthy positions). India is also pursuing conventional subs (P-75I) and considering SSGN derivatives from SSBN designs as interim options. Pure hunter-killers alone would limit India's ability to project power against surface fleets

I largely agree with your ISR Limitations and Missile Guidance problem you mentioned unless anyone can correct me. Plans for a 52-satellite military surveillance constellation (SBS-III, by ~2029, with SAR/optical for persistent coverage) and Naval Constellation are underway, but it's not yet at US/China scale.

 

[Parthu]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

There will be some effect on maneuverability, but nothing too drastic. A ~200 MWth powerplant is sufficient to drive a boat of this size to meet all required speed & maneuverability criteria. All nuclear navies are converging toward this ~10,000T ballpark (+/- 20%) w/ VLS for their contemporary attack submarine requirements. This goes for the Virginia (US), Yasen-M (Russia), SSN-AUKUS (UK/Australia) and Type-095 (China).

France with their Suffren is the only exception. But it's also the only one which has a significantly less powerful reactor (~150 MWth), so there's your reason for why that is so.

As of ISR, you must understand that our P-77s will only be operational by around the late 2030s at the earliest. So you must think on the basis of what we are working toward having by the next ~15 years, not what we have right now. So the SBS Phase-III constellations will be fully implemented by that point.

That said, it's not true that we have no ISR capability at the moment. There are multiple SAR & other ISR-capable satellites in orbit (RISAT series, CARTOSAT-series) that can cover significant portions of the IOR if needed. And these inputs will be used alongside coastal, shipborne & airborne radar inputs, transmitted to command via datalinks/SATCOM and fed to the submarines via VLF & ELF communication facilities in Tamil Nadu (new ones coming up in Telangana as well).

Additionally, watch this video from 9:00 onwards:

Reading between the lines, it would appear that integrating inputs from the 'Fish Hook' SOSUS/IUSS hydrophone array have been integrated into our detection/kill chains (at least as of 2023) as a 'tripwire' against PLAN assets (even subsurface ones) crossing over into the IOR.



There is also talk that the SOSUS network could be extended till Mainland India (somewhere in TN), essentially placing another tripwire for those seeking to cross into the Bay of Bengal (where our INS Varsha submarine pens would be located).

This portion of the array will most likely be our own equipment.

 

[FalconSlayers]

Are we compromising on SSN by making it hybrid with SSGN ?

USN or PLAN has much advanced and reliable and every where available ISR, they have large satellite constellation.

Hence for them, guiding AShM to target, anywhere is the world is not difficult.

But for us ? Our ISR is quite poor, we can not guide AShM to target reliably, as we dont have our own large satellite network.

Hence should we focus on smaller SSN, so that they are very menurable, as adding VLS and making it 10000 tonnes makes it bad for menurabality.

Just hunter killer, with amazing speed, menurabality, should be our choice V/S an hybrid SSN+SSGN.

(Offtopic: infact i doubt how are we gonna use 800km brahmos range and >1500km LRAShM range ?

Our AWACS or ISTAR plateform for navy is very low and with limited range, chinese CBG will target our ISR plateform before our ISR plateform even came close to their CBG to track it.

We dont have hundreds of satellite in LEO, so that we can move at the same place on earth within minutes.

LRAShM us hypersonic, and CBG is a moving target, we need hundreds of satellite to reliably target their CBG, or extremely long range ISR plateform.

But we have none )

An SSN/SSGN would usually carry land-attack cruise missiles for large scale salvo attacks on enemy ground targets in their cells.