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

[randomradio]

SSBN.

That was designed way before though.

Arihant was designed in the 90s, S5 class began in 2006. Now it's the SSN's turn. After that we will see the SSK design. Post which we should have the manpower necessary to conduct simultaneous design of two classes of subs in parallel at the minimum.

 

[vvabhiram]

This is interesting. The video claims we're receiving a brand new SSN called Bratsk from Russia in 2026 which will be christened INS Chakra III. At the same time we're also receiving a replacement for the INS Chakra II we just returned to Russia. This will likely be another Akula class submarine. Does anybody know anything more about this?

Journalist Sandeep reported this in India today. Actually, Bratsk is replacement for Chakra II only and it will be called as Chakra III. We wont be getting two SSN's.

Why Russia is offering India old submarines

The offer of three or more ex-Soviet submarines in the short term plugs a gap in the missing numbers as the Indian Navy struggles to acquire new units

www.indiatoday.in

 

[Ashwin]

Why India could be leasing a second nuclear powered attack submarine from Russia

New Delhi signed a $3 billion lease deal with Moscow in 2019 for the Chakra-3 submarine. But with growing Chinese naval presence and delays in its own nuclear submarine project, India needs as many submarines as it can get

www.indiatoday.in

 

[randomradio]

Why India could be leasing a second nuclear powered attack submarine from Russia

New Delhi signed a $3 billion lease deal with Moscow in 2019 for the Chakra-3 submarine. But with growing Chinese naval presence and delays in its own nuclear submarine project, India needs as many submarines as it can get

www.indiatoday.in

This is a way better option than buying 3 Kilos.

But I guess with the 2nd indigenous carrier being delayed, even the 3 Kilos can be exercised. The navy has the budget for it.

 

[Gautam]

I forgot if I posted this here. So posting again:

https://twitter.com/x/status/1320175768438190080

https://twitter.com/x/status/1318092092573425664

 

[Arctic Wolf]

Have the P75 Alpha SSNs been approved (as per TOI, it was supposed to be approved within 1-2 months of April)?

 

[Ashwin]

Have the P75 Alpha SSNs been approved (as per TOI, it was supposed to be approved within 1-2 months of April)?

CCS is yet to approve.

Latest: India's nuclear sharks

But it's only about production which cannot go ahead without S4* getting in to the water.

From S5 they need a bigger yard ( which is 12k+ ton sub merged)

SSN is suppose to start fabrication in the current yard at SBC.

 

[jetray]

CCS is yet to approve.

Latest: India's nuclear sharks

But it's only about production which cannot go ahead without S4* getting in to the water.

From S5 they need a bigger yard ( which is 12k+ ton sub merged)

SSN is suppose to start fabrication in the current yard at SBC.

View attachment 21049

so "Design sub group" is located 100's of miles away from the nearest coast. It is also way too far away from "ship building center" that any design validation will require a lot of round trips.

Lets be politically correct & have one in himalaya's as well and claim national integration.

 

[Ashwin]

https://twitter.com/x/status/1444631861502767109

@Parthu

 

[gearedcombustor]

BHEL Annual Report states that they delivered first indigenously developed Reserve propulsion motor and a 500 kW Main Motor Generator for submarine applications in 2020-21

BHEL is working with Navy to develop a Lithium-ion battery suite for submarine applications.

BHEL has developed a 350 kW reversible Permanent Magnet Synchronous propulsion unit which has successfully completed 2500 hours of endurance testing. ( Possibly a subscale prototype for SSK/SSN drive motor)

 

[gearedcombustor]

BHEL Annual Report states that they delivered first indigenously developed Reserve propulsion motor and a 500 kW Main Motor Generator for submarine applications in 2020-21

BHEL is working with Navy to develop a Lithium-ion battery suite for submarine applications.

BHEL has developed a 350 kW reversible Permanent Magnet Synchronous propulsion unit which has successfully completed 2500 hours of endurance testing. ( Possibly a subscale prototype for SSK/SSN drive motor)

For further clarity

Main Motor Generator is the generator used to generate electricity for battery charging & onboard use from the main gear box driving the prop shaft connected to the nuclear steam turbine.

Reserve propulsion motor is the backup way to drive the shaft via the gearbox from the battery energy if the main reactor or the main plant fails/tripped.

 

[Gautam]

BHEL Annual Report states that they delivered first indigenously developed Reserve propulsion motor and a 500 kW Main Motor Generator for submarine applications in 2020-21

BHEL is working with Navy to develop a Lithium-ion battery suite for submarine applications.

BHEL has developed a 350 kW reversible Permanent Magnet Synchronous propulsion unit which has successfully completed 2500 hours of endurance testing. ( Possibly a subscale prototype for SSK/SSN drive motor)

The Navy in their tender wanted a scaled down (1 MW) electric motor for testing out the new pumpjet. They would eventually scale up the motor to a max rated power of 35 MW in forward mode & 12.5 MW in Astern mode.

If BHEL is at 350 kW level they are probably testing a new type of motor. They have delivered 20-25 MW motors in the past for civil engineering projects. Scaling up shouldn't be a huge problem.

Besides BHEL, Megha Engineering Ltd. has a lot of experience in electric motors. Recently they delivered multiple electric motors of ~140MW for a massive water pumping & storage project in Andhra Pradesh. Of course the Navy's noise requirements are different form the requirements of civil projects.

 

[gearedcombustor]

BHEL Annual Report states that they delivered first indigenously developed Reserve propulsion motor and a 500 kW Main Motor Generator for submarine applications in 2020-21

BHEL is working with Navy to develop a Lithium-ion battery suite for submarine applications.

BHEL has developed a 350 kW reversible Permanent Magnet Synchronous propulsion unit which has successfully completed 2500 hours of endurance testing. ( Possibly a subscale prototype for SSK/SSN drive motor)

This is probably the first stage of the PMSM work for SSK's and SSN's.

We have seen an EoI for a 5 MW drive motor for an SSK retrofit - likely Kilo class but don't know whether BHEL will go with PMSM or stick to the original DC type in the Kilo.

5 MW is the next step for BHEL and can probably be delivered very quickly.

An IN EoI for 35 MW drive motor for pumpjet propulsion also exists. A 35 MW PMSM will be challenging to design - the technical risk will depend on achieving the compact design. They should probably have a backup plan sticking to the steam propulsion instead of attempting NEP/IEP for this.

The only parallel motor design is the 20 MW motor in the Barracuda/Suffren. I am not sure if it is PMSM or DC. Can't find any info from ECA-Jeumont or DCNS. The Siemens & Jeumont designs go to 4 MW max and the Japanese SMC-8 is 8 MW.

The Navy in their tender wanted a scaled down (1 MW) electric motor for testing out the new pumpjet. They would eventually scale up the motor to a max rated power of 35 MW in forward mode & 12.5 MW in Astern mode.

If BHEL is at 350 kW level they are probably testing a new type of motor. They have delivered 20-25 MW motors in the past for civil engineering projects. Scaling up shouldn't be a huge problem.

Besides BHEL, Megha Engineering Ltd. has a lot of experience in electric motors. Recently they delivered multiple electric motors of ~140MW for a massive water pumping & storage project in Andhra Pradesh. Of course the Navy's noise requirements are different form the requirements of civil projects.

BHEL is very capable but those civil and locomotive motors are not the permanent magnet synchronous type. They are either induction or DC.
BHEL is very capable and will probably deliver without any major issues. The main challenges will be regarding maintainability, compact size etc.

Compact PMSM motors are a few and far between.

 

[Gautam]

This is probably the first stage of the PMSM work for SSK's and SSN's.

We have seen an EoI for a 5 MW drive motor for an SSK retrofit - likely Kilo class but don't know whether BHEL will go with PMSM or stick to the original DC type in the Kilo.

5 MW is the next step for BHEL and can probably be delivered very quickly.

Wonder why they are spending money on replacing the propeller of SSKs with pumpjets. Will give them some experience with operating pumpjet propelled subs I guess.

BHEL is very capable but those civil and locomotive motors are not the permanent magnet synchronous type. They are either induction or DC.
BHEL is very capable and will probably deliver without any major issues. The main challenges will be regarding maintainability, compact size etc.

Compact PMSM motors are a few and far between.

One thing that worries me about PMSM is the use of rare-earth minerals for making the permanent magnets.

By 2018 DMRL has developed SmCo5, Sm2Co17 and Nd-Fe-B based magnets with high energy density (18-35 MGOe) that enabling device miniaturisation. For PSMS to be used on subs energy densities of ~50 MGOe are preferable, we should get there in a few years. Non-rare earth magnets (like Ferrite magnet) barely give you 1-5 MGOe. Those are not even in the question.

The rare earth metals mentioned above are Samarium (Sm), Cobalt (Co) & Neodymium (Nd). India has the 4th or 5th largest reserves of Neodymium, they are found on the same Monazite ore from which BARC extracts Thorium. IREL has been given responsibility to extract Nd with the help of BARC.

Of course the metal will be needed in large quantity if we are to make 35 MW motors. Therefore the extraction has to be scaled up significantly. IREL's track record isn't exactly convincing. If they fail to deliver we are going to have to import, probably from Australia. These are not things that the Navy alone can manage, New Delhi has to do its bit.

Well at least BHEL is proving the motor. NPOL has been testing the pumpjet propulsor for many years now. Maybe they can get L&T to fabricate a larger version.

 

[gearedcombustor]

Wonder why they are spending money on replacing the propeller of SSKs with pumpjets. Will give them some experience with operating pumpjet propelled subs I guess.

One thing that worries me about PMSM is the use of rare-earth minerals for making the permanent magnets.

By 2018 DMRL has developed SmCo5, Sm2Co17 and Nd-Fe-B based magnets with high energy density (18-35 MGOe) that enabling device miniaturisation. For PSMS to be used on subs energy densities of ~50 MGOe are preferable, we should get there in a few years. Non-rare earth magnets (like Ferrite magnet) barely give you 1-5 MGOe. Those are not even in the question.

The rare earth metals mentioned above are Samarium (Sm), Cobalt (Co) & Neodymium (Nd). India has the 4th or 5th largest reserves of Neodymium, they are found on the same Monazite ore from which BARC extracts Thorium. IREL has been given responsibility to extract Nd with the help of BARC.

Of course the metal will be needed in large quantity if we are to make 35 MW motors. Therefore the extraction has to be scaled up significantly. IREL's track record isn't exactly convincing. If they fail to deliver we are going to have to import, probably from Australia. These are not things that the Navy alone can manage, New Delhi has to do its bit.

Well at least BHEL is proving the motor. NPOL has been testing the pumpjet propulsor for many years now. Maybe they can get L&T to fabricate a larger version.

The SSK won't have a pumpjet. The 5MW motor is just a indigenous replacement for the current motor in the Kilo. Probably just as a technology proving platform before scaling up further to enable them to get realworld reliability data.

All the rare earths are currently available in the open market and can be imported (for now). Local extraction doesn't matter now and only comes into picture as a backup to ensure our strategic autonomy if the geopolitical situation gets worse.

DMRL/Midhani will still have to master the alloys formulation as only the elemental forms can be imported and no one will give alloys of this grade.

 

[randomradio]

The SSK won't have a pumpjet. The 5MW motor is just a indigenous replacement for the current motor in the Kilo. Probably just as a technology proving platform before scaling up further to enable them to get realworld reliability data.

All the rare earths are currently available in the open market and can be imported (for now). Local extraction doesn't matter now and only comes into picture as a backup to ensure our strategic autonomy if the geopolitical situation gets worse.

DMRL/Midhani will still have to master the alloys formulation as only the elemental forms can be imported and no one will give alloys of this grade.

I'm more inclined to believe the 5MW motor is for the P-75I. Don't think the motor will be made in time for the Kilos.

 

[gearedcombustor]

@Parthu No PWR type naval reactor can reach efficiencies above 25%. It's theoretically not possible. Even civil reactors with water/heavy water coolant can only reach efficiencies of max 30%. Going above 30% requires using Sodium/Lead as coolant. Going above 40 requires Gas cooled reactors.

Even Ultra Super Critical Coal power plants with Full Speed multi stage turbines with steam super heat temperatures at 600 deg C struggle to reach 45% efficiency.

To increase efficiency you need to increase coolant output temperatures. Due to void physics you cannot allow steam boiloff to occur within the flux space of the reactor, for PWR's boiloff doesn't occur at all before the steam generator due to pressures and they can only operate with coolant output temp of 320 deg C. For PHWR, boiloff can occur at tube outlet but not too much.

Due to all this issues, nuclear reactor turbines can only be inefficient half speed turbines. No reactor uses full speed turbines common in thermal coal/gas/oil power plants.

This situation gets worse in naval reactors as the number of turbines stages that can be crammed in, the size of the steam generator heat exchange area gets much worse

All in all - all PWR type naval reactors only have efficiencies less than 25%. Civil PWRs reach 30%. Fast breeders with sodium coolant at 590 deg C reach 40%.

Your claim on twitter that USN subs have 45% efficiency is inaccurate

 

[jetray]

Even Ultra Super Critical Coal power plants with Full Speed multi stage turbines with steam super heat temperatures at 600 deg C struggle to reach 45% efficiency.

so you are saying 50% of the energy output is wasted. Why not increase the amount of coolant (water in this case or use a coolant which has higher melting point) to absorb more heat?

 

[gearedcombustor]

so you are saying 50% of the energy output is wasted. Why not increase the amount of coolant (water in this case or use a coolant which has higher melting point) to absorb more heat?

For thermal plants, moving away from water to better heat transfer media is a scale/cost issue.

At that scale using anything except water is cost inefficient and non competitive. They are trying to improve metallurgy to increase efficiency without moving away from water. Using CO2 is an option but so much CO2 will be costly to obtain and maintain and not economically viable.

For reactors, you can't increase output temperatures because due to pressure metallurgical and void issues. You cannot allow water to convert to steam within the Reactor flux area(where the fission happens) as the voids generated will be devoid of the moderator(water) and will increase the reactivity and turn into Chernobyl. To avoid this you need to keep water at high pressures - due to metallurgical and manufacturing reasons the current max pressure seen in reactors is around 16 MPa. The high pressure water instead is flown through a steam generator where the heat is transferred to low pressure water which converts to steam and then turns the turbine.

There is another type of reactor called the Boiling water reactor where boiloff happens above the reactor head space but the steam temperature here is very low and inefficient.

The sodium/lead cooled reactors have high efficiencies but still cannot exceed coal.

There are reactor designs like High-temperature gas reactor - Wikipedia HTRs that have outlet temperatures of 1000 deg C to have high efficiencies but there are serious maintenance issues preventing them from being operationalised. Molten salt reactors are targeting 1400 deg C but metallurgical issues are preventing them from being built.

 

[Ashwin]

@Parthu No PWR type naval reactor can reach efficiencies above 25%. It's theoretically not possible. Even civil reactors with water/heavy water coolant can only reach efficiencies of max 30%. Going above 30% requires using Sodium/Lead as coolant. Going above 40 requires Gas cooled reactors.

Even Ultra Super Critical Coal power plants with Full Speed multi stage turbines with steam super heat temperatures at 600 deg C struggle to reach 45% efficiency.

To increase efficiency you need to increase coolant output temperatures. Due to void physics you cannot allow steam boiloff to occur within the flux space of the reactor, for PWR's boiloff doesn't occur at all before the steam generator due to pressures and they can only operate with coolant output temp of 320 deg C. For PHWR, boiloff can occur at tube outlet but not too much.

Due to all this issues, nuclear reactor turbines can only be inefficient half speed turbines. No reactor uses full speed turbines common in thermal coal/gas/oil power plants.

This situation gets worse in naval reactors as the number of turbines stages that can be crammed in, the size of the steam generator heat exchange area gets much worse

All in all - all PWR type naval reactors only have efficiencies less than 25%. Civil PWRs reach 30%. Fast breeders with sodium coolant at 590 deg C reach 40%.

Your claim on twitter that USN subs have 45% efficiency is inaccurate

I think, you are confusing terms. He is referring to enrichment of the fuel not efficiency.

Currently, US and UK naval reactors are fueled by weapon-grade HEU (93.5% U-235). Russia and India also use HEU (≥ 20% U-235). The other two countries with nuclear submarines, China and France, use LEU.

US study of reactor and fuel types to enable naval reactors to shift from HEU fuel

Alan Kuperman, Frank von Hippel In February 2020, the US Department of Energy's office of Defense Nuclear Nonproliferation released its report, Initial Evaluation of Fuel-Reactor Concepts for Advanced LEU Fuel Development, a screening study for potential fuel and reactor types...

fissilematerials.org