Indian Nuclear Submarines -3

The Military Issues & History Forum is a venue to discuss issues relating to the military aspects of the Indian Armed Forces, whether the past, present or future. We request members to kindly stay within the mandate of this forum and keep their exchanges of views, on a civilised level, however vehemently any disagreement may be felt. All feedback regarding forum usage may be sent to the moderators using the Feedback Form or by clicking the Report Post Icon in any objectionable post for proper action. Please note that the views expressed by the Members and Moderators on these discussion boards are that of the individuals only and do not reflect the official policy or view of the Bharat-Rakshak.com Website. Copyright Violation is strictly prohibited and may result in revocation of your posting rights - please read the FAQ for full details. Users must also abide by the Forum Guidelines at all times.
Post Reply
fanne
BRF Oldie
Posts: 4282
Joined: 11 Feb 1999 12:31

Re: Indian Nuclear Submarines -3

Post by fanne »

chetak wrote:
VKumar wrote:One nuclear submarine per year till we have 20.
aren't the pakis still eating grass, just like their uncle bhutto promised them

He was the glib talking to the gullible and rhetoric was the only weapon in his hand.

Sochta hoon keh woh kitne masoom the, kya se kya ho gaye, dekhte dekhte.
Not if we make say 95% of it at home. 20 is overkill; but some 6-12 SSBN, and 6-12 SSN will do just fine. You keep on refining and putting next generation is batch of 3-4 to keep them relevant (as anti sub tech will also grow). They are real tickets to power, backed by tech and intent (and also Modiji and not Rahul).
chetak
BRF Oldie
Posts: 32226
Joined: 16 May 2008 12:00

Re: Indian Nuclear Submarines -3

Post by chetak »

fanne wrote:
chetak wrote:
aren't the pakis still eating grass, just like their uncle bhutto promised them

He was the glib talking to the gullible and rhetoric was the only weapon in his hand.

Sochta hoon keh woh kitne masoom the, kya se kya ho gaye, dekhte dekhte.
Not if we make say 95% of it at home. 20 is overkill; but some 6-12 SSBN, and 6-12 SSN will do just fine. You keep on refining and putting next generation is batch of 3-4 to keep them relevant (as anti sub tech will also grow). They are real tickets to power, backed by tech and intent (and also Modiji and not Rahul).
I understand where you are coming from, and it will happen, in the fullness of time.

But we also need the economy to first blossom because we need the resources to round out the rough edges of our society and then really bloom to keep pace with such ambitions.
Barath
BRFite
Posts: 474
Joined: 11 Feb 2019 19:06

Re: Indian Nuclear Submarines -3

Post by Barath »

Wasn't the doctrine for 5 or 6 SSBN for India. ? Though I can't find a reference to confirm.

Which could possibly lead to go slow for manufacturing after the first S5 is commissioned, unless they retire Arihant.. :wink:

Also, if I recall, there were only 3 S5 submarines supposed to be in the class. Ref the article below

https://www.indiatoday.in/magazine/the- ... 2017-12-10

So let's look at it other ways and speculate/make some educated guesses

Each S5 i supposed to have 16 MIRV missiles, do that's 48 warheads - or realistically, taking decoys into consideration , about 25-30 warheads. Three S5 would there could have 75-90 warheads. The number of Arihant stretch submarines in service at the time, would be a guess, but lets say that an Arihant submarine has a life of 20 years with 10 years between refueling. That would imply ~2-3 so Arihant/Arihant stretch are operational, when the 3rd S5 is built. (which is not unreasonable guess given build times, life and refueling). This would add another ~40 warheads to the mix (depending on K4 vs K15, arihant stretch etc - lets asume 16 per arihant stretch and say 8 for arihant with a 50-50 mix)

So we are talking ~120 +/- 10 some warheads in the naval fleet at 5-6 SSBN when the 3rd S5 is launched (allowing for more warheads than decoys)

Now SSBN aren't toys or playthings, but an expression of the will and strategy of the Strategic Nuclear Force. Good luck getting much info on outlook, size and mix of India's nuclear deterrent. But there are some papers out there. As per this, the Indian nuclear is based around minimal viable deterrence, with a counter-value strategy, a triad and an estimate of say 160 warheads at fair steady state. There's a mild rise in the same recently.

It would be a good bet to say that both Indian tactical and strategic nukes in land (prahar, Agni etc) and air (rafael/MKI from mirage/jaguar) aren't going to disappear

120/160 or 200 total warheads is rather heavily weighted towards subs, especially if you consider possibility of land based MIRV. Even allowing for a slight rise in total warheads, it's a bit heavily weighted. (guess). And as we get to even future decades, where Arihant class gets retired and additional S5 or S6 subs start coming in, the numbers will just go up more.

Now we come to survivability. SSBN are seen as more survivable and thus second strike oriented. However, this is not an absolute, with advances in seabed sensors and tracking. Guessing survivability is also one of the unknowns, but it's also possible for an enemy to flood the area with SSN and try to strike a SSBN as it launches, to try and suppress the last launches.

India's strategy, it has been speculated/mentioned is to set up bastions in the Bay of Bengal from which one could sit in the deep and still be in strike range.

The Indian Ocean gets a little far for strike region, and sending SSBN to the South China Sea means sending it through shallow waters and straits where it can be more easily detected and tracked and taking a logistical burden of long trips for sailors requiring food etc. You dont want to chance the heart of your strategic detterent that way. Maybe just a minimal effort that you wouldn't mind losing.

The Arabian Sea would be for Pakistan, which is massive overkill, considering that all of Pakistan is well within reach of land based and air based missiles. The Arabian sea is also a lot shallower for a lot longer distance. Maybe 1 SSBN useful (at best)

Having multiple SSBN in a single bastion actually reduces survivability. Having multiple bastions in the bay of Bengal - will be limited.

Having just 3-4 SSBN means that one could be tracked or could be out of service or in refueling and you lose a big chunk of your deterrence. (This has not stopped France and UK from doing that)

Having more nukes and nuke platforms than justified by your strategic deterrence force structure / nuclear posture is as good as setting your money on fire and dumping it in the sea.

As the arihant series retires, more capable and large SSBN (either S5 or putative successor S6) may be justified.

But as per what is known of Indian nuclear doctrine, and survavibility, and force mix, you are unlikely to go far beyond 6, and 12 is a pipe dream

In short : ~6 SSBN +/- a couple seems to be right sizing it, and 12 SSBN seems unjustified by projected Indian nuclear doctrine & policy , survivability, nuclear force structure, threat, tactics and simple economics . Forget 20. Of course those SSBNs will be far more capable than current

If one must fanboy, one should fantasize on more SSN, which after all, you can more easily survive losing. And which have many different tasks, including suppressing enemy SSBN launches, tailing enemy SSBN and enemy SSN or carriers, targeting enemy ships, land attack strike by cruise or ballistic missiles, escorting SSBN and carriers, guarding SSBN in bastions, special forces delivery/pickup, intelligence missions and undersea cable tapping, or even nuclear torpedo strike. ...
srai
BRF Oldie
Posts: 5220
Joined: 23 Oct 2001 11:31

Re: Indian Nuclear Submarines -3

Post by srai »

^^^

Given the IN’s similar defense budgets/size as the Royal Navy and French Navy, SSN and SSBN fleet can be projected.
  • 4 x SSBN
  • 6 x SSN
That also more or less lines up with current IN procurement plans.
LakshmanPST
BRFite
Posts: 673
Joined: 05 Apr 2019 18:23

Re: Indian Nuclear Submarines -3

Post by LakshmanPST »

India's Nuclear Force Structure 2025
2016 article by Brig. Gurmeet Kanwal (retd.)--->
https://carnegieendowment.org/2016/06/3 ... -pub-63988

This para summarises various suggestions given about SSBN fleet--->
Brigadier Vijay Nair is of the view that India needs four SSBNs, each with 16 SLBMs; Bharat Karnad suggests five SSBNs in India’s nuclear force, each with 12 SLBMs; and Rear Admiral Raja Menon has recommended a force of six SSBNs, each equipped with 12 SLBMs. Six SSBNs are obviously preferable to four or five because they provide redundancy. However, the difference in capital costs would be considerable. Sailing four SSBNs with one on patrol at all times should meet India’s requirements for deterrence well into the first few decades of the twenty-first century.
The suggestions seem to be 5-6 SSBNs with total 60-72 SLBMs...
After commissioning of S4*, India will have 4 SSBNs with total 72 K15s or 24 K5s/K6s...
Maria
BRFite
Posts: 212
Joined: 15 Aug 2020 13:50

Re: Indian Nuclear Submarines -3

Post by Maria »

LakshmanPST wrote:India's Nuclear Force Structure 2025
2016 article by Brig. Gurmeet Kanwal (retd.)--->
https://carnegieendowment.org/2016/06/3 ... -pub-63988

This para summarises various suggestions given about SSBN fleet--->
Brigadier Vijay Nair is of the view that India needs four SSBNs, each with 16 SLBMs; Bharat Karnad suggests five SSBNs in India’s nuclear force, each with 12 SLBMs; and Rear Admiral Raja Menon has recommended a force of six SSBNs, each equipped with 12 SLBMs. Six SSBNs are obviously preferable to four or five because they provide redundancy. However, the difference in capital costs would be considerable. Sailing four SSBNs with one on patrol at all times should meet India’s requirements for deterrence well into the first few decades of the twenty-first century.
The suggestions seem to be 5-6 SSBNs with total 60-72 SLBMs...
After commissioning of S4*, India will have 4 SSBNs with total 72 K15s or 24 K5s/K6s...
I hope the above recommendations are just recommendations. As the economy grows we will need more, not only to stave off PRC but also the USA.
LakshmanPST
BRFite
Posts: 673
Joined: 05 Apr 2019 18:23

Re: Indian Nuclear Submarines -3

Post by LakshmanPST »

Once the three S5s are commissioned, we will have 7 SSBNs with 72 K4/K5/K6s capacity...
But it will be reality only in 2040s...
S_Madhukar
BRFite
Posts: 513
Joined: 27 Mar 2019 18:15

Re: Indian Nuclear Submarines -3

Post by S_Madhukar »

That sounds like such a low number for 20 years from now. If the hull or missile technology landscape changes What will we do, buy off the shelf if anyone will sell or develop in-house ? We should get these first ones out before the decade is out and start looking for the next ones
LakshmanPST
BRFite
Posts: 673
Joined: 05 Apr 2019 18:23

Re: Indian Nuclear Submarines -3

Post by LakshmanPST »

^^^I don't think we need to have deterrence against any other country except Pak or China in the next 50 years... There won't be any significant increase in the no. of targets within these countries...

We may not need more SSBNs unless BMD technology or Anti-Submarine Technology of China improves greatly...
Pak can be taken care by land based missiles itself...

IMO, it will be waste of money to have more SSBNs...
Even US and Russia have only 14 and 12 SSBNs inspite of large area of operations and potential targets...

Currently planned 7 SSBNs would do fine for the near future... We should focus more on SSNs and SSKs to counter PLAN...
Barath
BRFite
Posts: 474
Joined: 11 Feb 2019 19:06

Re: Indian Nuclear Submarines -3

Post by Barath »

LakshmanPST wrote:Once the three S5s are commissioned, we will have 7 SSBNs with 72 K4/K5/K6s capacity...
But it will be reality only in 2040s...
I figure by the time the 3rd S5 is commissioned, Arihant will retire.

10 years between refueling. I doubt if they would go for a 2nd Refueling. First of a kind, and probably flogged in usage, including acquiring experience, training crews, creating operational procedures etc..
Rakesh
Forum Moderator
Posts: 18190
Joined: 15 Jan 2004 12:31
Location: Planet Earth
Contact:

Re: Indian Nuclear Submarines -3

Post by Rakesh »

Article is a few months old.

First three indigenous nuclear attack submarines to be 95% made in India
http://timesofindia.indiatimes.com/arti ... 481098.cms
13 June 2021
Pratyush
BRF Oldie
Posts: 12187
Joined: 05 Mar 2010 15:13

Re: Indian Nuclear Submarines -3

Post by Pratyush »

^^^

If this design is going to be substantially different from the Ahrihant class boats. Then it will be greatly disappointing if they don't simultaneously design a conventional submarine based on the same design principles.
Aditya_V
BRF Oldie
Posts: 14331
Joined: 05 Apr 2006 16:25

Re: Indian Nuclear Submarines -3

Post by Aditya_V »

I think the learnings from Conventional submarines are being to used to design and Build these.
Karan M
Forum Moderator
Posts: 20772
Joined: 19 Mar 2010 00:58

Re: Indian Nuclear Submarines -3

Post by Karan M »

LakshmanPST wrote:^^^I don't think we need to have deterrence against any other country except Pak or China in the next 50 years... There won't be any significant increase in the no. of targets within these countries...
As India's profile rises so will its threats. We need worldwide deterrence. Never forget our past history of colonialism.
kit
BRF Oldie
Posts: 6278
Joined: 13 Jul 2006 18:16

Re: Indian Nuclear Submarines -3

Post by kit »

Karan M wrote:
LakshmanPST wrote:^^^I don't think we need to have deterrence against any other country except Pak or China in the next 50 years... There won't be any significant increase in the no. of targets within these countries...
As India's profile rises so will its threats. We need worldwide deterrence. Never forget our past history of colonialism.
+1
There is no QUAD when push comes to shove.
V_Raman
BRFite
Posts: 1379
Joined: 04 Sep 2008 22:25

Re: Indian Nuclear Submarines -3

Post by V_Raman »

there is no way india will have 5-6 nuclear submarines in 20 years in addition to the arihant class. india does not move that fast. we might have 1 or 2 more indigenous ones.
Vicky
BRFite -Trainee
Posts: 79
Joined: 23 Aug 2021 19:33

Re: Indian Nuclear Submarines -3

Post by Vicky »

https://twitter.com/YusufDFI/status/143 ... 45280?s=19
The open proliferation of naval nuclear propulsion tech opens opportunities for India as well. The target for India should be France with its LEU NNR. Indian navy has interest in it. A smarting France perhaps will see potential in doing biz with India in this field.
More than the US NNR which uses weapons grade Uranium, it makes sense for India to go with French LEU design. India’s naval deployment requirement matches that of France rather than the US.
Why are the usual suspects pitching a French reactor design again saying that an enormous opportunity has opened up with the Aukus deal?
Last time I checked we have crossed this technology barrier and can improve our existing design from the Arihant and make our own SSN. Why go back to a foreign design? Why is this regressive thought process so common?

We already have HEU production facilities - Why should we go back to the inefficient LEU?

Should BARC throw away all it's learning and work for some diplomacy? What's the strategic gain here? What objective will we solve by getting a French design instead of using the existing compact CLWR and our own SSN?

What is the thought process pitching permanent screwdrivergiri so common?
Rakesh
Forum Moderator
Posts: 18190
Joined: 15 Jan 2004 12:31
Location: Planet Earth
Contact:

Re: Indian Nuclear Submarines -3

Post by Rakesh »

Vicky wrote:Why are the usual suspects pitching a French reactor design again saying that an enormous opportunity has opened up with the Aukus deal?
Last time I checked we have crossed this technology barrier and can improve our existing design from the Arihant and make our own SSN. Why go back to a foreign design? Why is this regressive thought process so common?

We already have HEU production facilities - Why should we go back to the inefficient LEU?

Should BARC throw away all it's learning and work for some diplomacy? What's the strategic gain here? What objective will we solve by getting a French design instead of using the existing compact CLWR and our own SSN?

What is the thought process pitching permanent screwdrivergiri so common?
The nuclear reactor on the Arihant cannot be used on an Indian SSN. You need a more powerful reactor than the 83 MW reactor found on the Arihant Class SSBN.

The Barracuda SSN uses a LEU design. Now there are pluses and minus to both HEU and LEU reactors, but the Indian Navy has envisaged interest in the design and even got a presentation from Naval Group on that front. So there are obviously some key advantages that the Indian Navy sees in the French LEU reactor. What that is, will likely never be revealed for obvious reasons of secrecy.

BARC is not throwing anything away. In fact, the HEU reactor will continue to be used on the Arihant Class and the succeeding classes. It will be further improved upon as time progresses and as newer vessels are built.

I am making BIG assumptions here, but I guess one of the reasons the Indian Navy is interested in the French LEU reactor is the quicker refueling time versus a HEU reactor. Quicker refueling = more availability at sea. Also avoids cutting open the boat to refuel the reactor.

See these tweets below...

https://twitter.com/daeroplate_v2/statu ... 12642?s=20 ---> The 25 yr sealed reactor lifecycle tech will actually greatly reduce costs for us vs a 10 yr chalu reactor. no need for expensive refueling and dockside handling facilities.... France has a golden chance here to recover from its humiliation and bag the P-75I SSN as a combo thing.

https://twitter.com/daeroplate_v2/statu ... 25410?s=20 ---> Reactor refueling takes the SSN out of service for years. Entire hull is cut open...vast cost and complexity plus safety is paramount...a nukular incident in middle of Vizag will unleash a political shitstorm.
Vicky
BRFite -Trainee
Posts: 79
Joined: 23 Aug 2021 19:33

Re: Indian Nuclear Submarines -3

Post by Vicky »

Rakesh wrote: BARC is not throwing anything away. In fact, the HEU reactor will continue to be used on the Arihant Class and the succeeding classes. It will be further improved upon as time progresses and as newer vessels are built.

I am making BIG assumptions here, but I guess one of the reasons the Indian Navy is interested in the French LEU reactor is the quicker refueling time versus a HEU reactor. Quicker refueling = more availability at sea. Also avoids cutting open the boat to refuel the reactor.
I believe BARC certainly has that capability to build a new more powerful design based on the Arihant's CLWR-B1 and a B2 design project exists for sure as I quoted from my post in the other thread.
AFAIK as per opensource info, There are atleast two current design projects at BARC - one is B1 and other is B2. B1 might be the original ATV & B2 it's successor.

There are references to B1/B2 in BARC Founders day speech 2018 and BARC newsletter Sep-Oct 2011 both of which are available on barc.gov.in . They are linked on wikipedia.

Based on one openly available document on dae.gov.in, there are atleast three compact LWR based on the original design (B1?)

So infer.
Such upgrade does not necessarily require a total redesign of the reactor - Some of the improvements to go from 83 MWt to 120 MWt can be :
1) Higher burnup rated fuel rods- Solvable without foreign help as PFBR already goes to much higher enrichments and burnups of much more energy dense Pu against the less dense U235.
2) New steam generator - Trivial for BARC
3) New turbine - Trivial for BHEL/L&T
4) Reactor pressure vessel modifications and resizing - Solvable at BARC
5) Higher flow rate but silent pumps - Solvable? Probably Yes

Going much larger than 120 MWt will require a total redesign of every component - every tube, switch, wire, sensor and everything. Time and Money problem - not a technology problem. BARC has already completed design work for the civil 900 MWe/2700 MWt IPWR-900 design and is conducting validation studies for various materials, forgings and equipment before construction approval is given.

BARC can go LEU if they want and SDB can simplify the refueling system by adding a hatch to the design. It's not a reactor design problem but a hull integrity design problem. Ball will be in the Navy's court - BARC probably won't face any hurdles.

France only went with LEU because they wanted to shut their govt owned enrichment facility that was used for the weapons program in 1996 and rely on commercial enrichment from multi country owned Urenco which will not enrich to HEU levels because of NPT reasons. It was just a legal thing. We don't have such constraints and we need some HEU for the three stage programme anyway and we are planning to increase our enrichment capacity for the IPWR-900 program with the new facility in that place.

Quote from https://uploads.fas.org/2016/12/Frances ... ulsion.pdf
In 1996, France decided to stop enriching uranium to HEU levels for weapons purposes. If the Navy had
wanted to use HEU fuel, it would have had to invest significant money to have its own HEU enrichment
facility. By choosing to only use LEU fuel with enrichments much less than 20 percent in the fissile
isotope uranium-235, France has saved money by purchasing from the commercial market. Moreover,
France’s decision to use LEU fuel for naval propulsion has not degraded the operational performance of
the ships.
BARC is also certainly capable of going 90%+ HEU and go the full packaged 25 year 0-refuel design. They will need to redesign the fuel rods to handle higher burnup and higher temperatures. BARC has solved most of these high burnup/high temperature problems in it's R&D for PFBR (albeit for plutonium) and have also designed fuel rods for this. BARC is also planning to solve this problem anyway with TRIGA fuel for IHTR program.

BARC IPWR-900 avg fuel burnup (5% U235 LEU) - 30 MW · day / kg
IGCAR PFBR avg fuel burnup ( 27.7% PuO2) - 134 MW · day / kg

The only problem is - Enrichment for 90%+ HEU will take up a lot of cascades in the enrichment facility and will require significant capacity upgradation at the proposed new facility. Since no foreign country will either supply LEU or HEU for military purposes since we are non-NPT - fuel has to be local and will take up enrichment capacity anyway.

The capacity increase required to go from the existing around 15% in arihant to 90%+ is marginal as the graph of Separative Work Units vs U235 % looks like below. It's much harder to make 5% LEU but incrementally pretty easy to take the step from 5% to 15% and much more easier to go to 90%.

Natural to 5% - A lot of work required - 900 SWU//tonne of NU
5% to 15% - Add 200 more SWU - 1100 SWU/tonne of NU - Arihant is probably here
90% - Add 150 more SWU - 1250 SWU/tonne of NU

Image

Let's not bother with refueling every 5 years instead of going full HEU by adding small amount of enrichment capacity. LEU should only be considered if BARC is not confident about it's capability to go HEU (unlikely) or Navy is okay with cutting open subs every 10 to 15 years (marginally likely.

Only the non proliferation ayatollahs are pitching for all countries including US to go LEU so that some they can allegedly sleep happy that the material won't be diverted for a weapons programme. Useless virtue signalling exercise that doesn't add any value for a non-rich non-superpower country like us and we already have nukes.
Prasad
BRF Oldie
Posts: 7793
Joined: 16 Nov 2007 00:53
Location: Chennai

Re: Indian Nuclear Submarines -3

Post by Prasad »

We will anyway need 2 lines - 1 each for arihant class and ssn class. So a common higher rated powerplant might make things simpler and cheaper.
Rakesh
Forum Moderator
Posts: 18190
Joined: 15 Jan 2004 12:31
Location: Planet Earth
Contact:

Re: Indian Nuclear Submarines -3

Post by Rakesh »

Vicky, thank you for your long post. Very informative and I have a whole bunch of questions to ask.

But for now, let me just post this...from the former Chief of Naval Staff, Indian Navy - Admiral Arun Prakash (retd).

https://twitter.com/arunp2810/status/14 ... 26497?s=20 ---> For years, US has been telling India that their laws make it impossible to share nuclear-propulsion tech with anyone, including allies. Even the Indo-US Nuclear deal & signing of all four ‘foundational agreements’ did not seem to matter. And now this…

https://twitter.com/sonaliranade/status ... 85795?s=20 ---> Anglo-saxons are different … I mean not different … I mean … you know…

https://twitter.com/arunp2810/status/14 ... 31459?s=20 ---> Actually, the US McMahon Act of 1946 had banned transfer of nuclear tech to even UK & Canada. Concessions were, obviously, later made to enable UK to field a triad. But yes, the Soviets/Russians have shown far more faith in entrusting us with 2 x SSNs.
ldev
BRF Oldie
Posts: 2616
Joined: 06 Nov 2002 12:31

Re: Indian Nuclear Submarines -3

Post by ldev »

Vicky wrote: Let's not bother with refueling every 5 years instead of going full HEU by adding small amount of enrichment capacity. LEU should only be considered if BARC is not confident about it's capability to go HEU (unlikely) or Navy is okay with cutting open subs every 10 to 15 years (marginally likely.
Two constraints which you are saying are not really constraints for India:

1. Domestic supplies of NU or reactor grade spent fuel not in the 123 agreement.
2. Enrichment capacity and re-processing if needed for spent fuel.

In which case far better to go in for HEU reactors and seal for 25 years otherwise the boat is out of commission for 1-2 years after every 5 years.
ldev
BRF Oldie
Posts: 2616
Joined: 06 Nov 2002 12:31

Re: Indian Nuclear Submarines -3

Post by ldev »

Vicky wrote: Going much larger than 120 MWt will require a total redesign of every component - every tube, switch, wire, sensor and everything. Time and Money problem - not a technology problem. BARC has already completed design work for the civil 900 MWe/2700 MWt IPWR-900 design and is conducting validation studies for various materials, forgings and equipment before construction approval is given.
You don't need to go more than 120 MWt for a 30,000-33,000 hp motor do you? If 100% of 120 MWt is used for driving purposes it can in theory support a ~40,000 hp motor. But there are other large power requirements on the sub so say a 30,000 hp motor for a 6000 ton displacement, which will give a submerged speed of ~25 knots. The Akula is larger at 8000 tons ++ going up all the way to 10,000 tons ++ for the later Akula 2 variants and hence the 190 MWt reactor. The LA class is ~6000 tons and has a 150 MWt reactor and a 33,000 hp motor, probably a lot of excess capacity in the reactor.....Yes a 120 MWt may not be capable of 35 knot speeds like the Akula or the LA Class but beyond a certain speed, it's noise and easily detectable. For Indian SSNs ~25 knots should be OK I think???

Added later: for USN and Russian Navy SSNs large transit distances e.g. across the Pacific or from the Barent Sea down to the Atlantic require that 30+ knot speed. For the IN it is distances in the northern Indian Ocean and upto the South China sea where IMO ~25 knots should be adequate. In any event for tactical operations high speed is easily detected and hence avoided.
Vicky
BRFite -Trainee
Posts: 79
Joined: 23 Aug 2021 19:33

Re: Indian Nuclear Submarines -3

Post by Vicky »

Also based on a cursory reading of PFBR related research papers published after 2004, BARC can either go up to 70% U235 enrichment or triple the burnup from my assumed current burnup in Arihant based on PFBR's Plutonium tech. This wasn't ready when Arihant was being built. We have that now, these rods were validated for Pu in FBTR around 2014.

BARC should go to 70% if they can in the current design and incrementally move to 90%+ later.

If the fuel rods, cladding material, rod weld material, neutron flux estimations are solved - 80% work on uprating the current 83 MWt design to a higher rating is solved. Rest all is normal redesign.

BARC can go upto 120MWt based on the base arihant design easily if they can source the fuel in sufficient quantity and enrichment from RMP.

Also we know that RMP capacity was tripled/quadrupled in the 2016-17 era. The other new facility also started construction in 2020.

All the pieces are falling into place.

If Navy wants any sensors DRDO doesn't have currently or unable to deliver like Flank Sonars, Towed Sonars, Optronic masts etc these particular subsystems can be imported from France or elsewhere and integrated into our design. No need to import a whole sub.

Also, they need to solve the HWT problem

Edit: Also remember the fact that Arihant/ATV project was an SSN project to begin with until the creative FinMin Chidu threatened to cancel it :cry: forcing the Navy to change it to the traid role by bolting on the VLS and the practically useless K-15s. Delete the VLS and the boat is likely to only have a displacement of 4500T instead of the current 6000T. At 83MWt it will have usable speed for our requirements and uprating to 120MWt will make it a formidable SSN.
Last edited by Vicky on 17 Sep 2021 16:04, edited 1 time in total.
Pratyush
BRF Oldie
Posts: 12187
Joined: 05 Mar 2010 15:13

Re: Indian Nuclear Submarines -3

Post by Pratyush »

The need for submarines to be tooling arround at 30 knots is something that I don't really understand. Other than transit it has no real application.

Besides all conventional submarines have a submerged top speed of 20 knots plus. But at the cost of endurance. The total power output of a conventional submarine on battery power will never be more than 5 MW.

So this need for a nuke boat to need 35 k + shp of propulsion power is beyond my understanding.

Even if I accept that the displacement difference between ssk and SSN is 4x or 5x.

The SSN can make do with under 20 k+ shp propulsion power. Unless the reactor is so inefficient that it will not be able to generate this power.

For eg. Charlie class was a 15k shp sub at 4800 tons top speed 24 knots.

Arihant class reactor is easily producing 20k + shp on a 6k ton hull.

What I am trying to say is that the Arihant reactor is quite suitable for SSN requirements.
Barath
BRFite
Posts: 474
Joined: 11 Feb 2019 19:06

Re: Indian Nuclear Submarines -3

Post by Barath »

SSN has the following needs:

a) Minimize transit time - high speed preferred

b) Escort your own aircraft carrier and provide an underwater ASW screen - Absolutely needs high speed to keep up with CAG

c) Intercept enemy carriers & ships in open/blue waters (instead of lying in wait in littorals for them to steam at you) - high speed preferred

d) Tail/Detect launch preparation of enemy SSBN and sprint to suppress it before the last SLBM is fired - high speed is critical

Other tasks like escorting your own SSBN, or egress or operations are less speed critical

Thus an Arihant reactor power output really may be insufficient, unless you are somehow able to shrink the width and other elements to have a small, streamlined sub
Barath
BRFite
Posts: 474
Joined: 11 Feb 2019 19:06

Re: Indian Nuclear Submarines -3

Post by Barath »

Vicky wrote:
if they can source the fuel in sufficient quantity and enrichment from RMP.
.
Not just RMP , also SMEF, Challakere

Pic of facility via here

SIPRI Yearbook 2020
India is also increasing its uranium enrichment capabilities and continues to produce enriched uranium at the expanded gas centrifuge facility at the Rattehalli Rare Materials Plant near Mysore, Karnataka, for highly enriched uranium (HEU) for use as naval reactor fuel. India is building a new industrial-scale centrifuge enrichment plant, the Special Material Enrichment Facility, near Challakere, Karnataka. This will be a dual-use facility that produces HEU for both military and civilian purposes. India’s expanding centrifuge enrichment capacity is motivated by plans to build new naval propulsion reactors. However, the HEU produced at the plants could also hypothetically be used to manufacture thermonuclear or boosted-fission nuclear weapons.
Arihant reputedly uses 40% HEU and needs refueling every ~10 years as per the initial reports. You expect the SSBN/SSN to be big drivers of uranium demand.

Increasing the HEU % may be used in a suitable reactor to increase power output or time between refueling [Which will increase operational availability and reduce costs]. But it may require the reactor etc to be redesigned , IDK
Last edited by Barath on 17 Sep 2021 19:39, edited 1 time in total.
arshyam
BRF Oldie
Posts: 4570
Joined: 11 Aug 2016 06:14

Re: Indian Nuclear Submarines -3

Post by arshyam »

Barath wrote:SSN has the following needs:

a) Minimize transit time - high speed preferred

b) Escort your own aircraft carrier and provide an underwater ASW screen - Absolutely needs high speed to keep up with CAG

c) Intercept enemy carriers & ships in open/blue waters (instead of lying in wait in littorals for them to steam at you) - high speed preferred

d) Tail/Detect launch preparation of enemy SSBN and sprint to suppress it before the last SLBM is fired - high speed is critical

Other tasks like escorting your own SSBN, or egress or operations are less speed critical

Thus an Arihant reactor power output really may be insufficient, unless you are somehow able to shrink the width and other elements to have a small, streamlined sub
The SSN's reactor would also need to be able to supply a sudden increase power in case the sub needs to put on speed and take evasive actions. Once detected by an enemy operator, speed becomes important, noise less so.

While this is true of missile subs too in case they get detected, their tendency to stay silent and lurk in safer waters means the probability of getting detected is lesser. Or so the theory goes :)
ldev
BRF Oldie
Posts: 2616
Joined: 06 Nov 2002 12:31

Re: Indian Nuclear Submarines -3

Post by ldev »

arshyam wrote: The SSN's reactor would also need to be able to supply a sudden increase power in case the sub needs to put on speed and take evasive actions. Once detected by an enemy operator, speed becomes important, noise less so.
Read this:
Submarine movies such as Crimson Tide and Hunter Killer use torpedo chase scenes for dramatic effect. The reality is that a torpedo maneuvering and hunting submarines that are frantically trying to evade is the least likely scenario in a modern submarine attack. As already noted, in a 21st Century torpedo attack, the target will likely never know it’s about to be destroyed. Modern submarine torpedoes have sound silencing built into their design and, unless they use their active sonar modes, they may not be detected until the moment before detonation.

A common event observed in naval exercises is two submarines passing within a few hundred meters of each other, detecting each other at the same time, and racing to get a shot off before the other. The other type of engagement is when one sub detects the other sooner, and often at range, resulting in a first shot, first kill. So, the underwater prolonged dogfights that are such beloved set pieces of modern submarine thrillers are just not the reality. Actual underwater combat occurs silently with very little reaction time to fend off an impending attack.
ldev
BRF Oldie
Posts: 2616
Joined: 06 Nov 2002 12:31

Re: Indian Nuclear Submarines -3

Post by ldev »

Barath wrote:SSN has the following needs:

[a) Minimize transit time - high speed preferred
In the Indian context where the radius of operation is likely to be anywhere from the Gulf of Aden to the South China sea to the upper reaches of the Southern Indian Ocean, transit distances are not huge compared to trans Pacific or Barent Sea to the South Atlantic or US East Coast to the Mediterranean Sea
b) Escort your own aircraft carrier and provide an underwater ASW screen - Absolutely needs high speed to keep up with CAG
Important for the US with nuclear powered aircraft carriers which can steam at ~30 knots with an endless supply of fuel. Not required for Indian aircraft carriers with much lower cruising speeds of ~15-18 knots to conserve fuel and range although top speeds are in the ~30 knot range.
c) Intercept enemy carriers & ships in open/blue waters (instead of lying in wait in littorals for them to steam at you) - high speed preferred

d) Tail/Detect launch preparation of enemy SSBN and sprint to suppress it before the last SLBM is fired - high speed is critical
Modern ISR for the IN via the P-8 and the Sea Guardian/Predator drones makes it much easier to keep track of enemy vessels and thereby position Indian submarines accordingly reducing the need for high speed transit in such instances. I remember reading an article where a senior IN officer said that they track every single PLAN vessel from the moment it enters the Indian Ocean via any of the straits until it goes back.
ldev
BRF Oldie
Posts: 2616
Joined: 06 Nov 2002 12:31

Re: Indian Nuclear Submarines -3

Post by ldev »

Vicky wrote:
All the pieces are falling into place.

If Navy wants any sensors DRDO doesn't have currently or unable to deliver like Flank Sonars, Towed Sonars, Optronic masts etc these particular subsystems can be imported from France or elsewhere and integrated into our design. No need to import a whole sub.

Also, they need to solve the HWT problem

Edit: Also remember the fact that Arihant/ATV project was an SSN project to begin with until the creative FinMin Chidu threatened to cancel it :cry: forcing the Navy to change it to the traid role by bolting on the VLS and the practically useless K-15s. Delete the VLS and the boat is likely to only have a displacement of 4500T instead of the current 6000T. At 83MWt it will have usable speed for our requirements and uprating to 120MWt will make it a formidable SSN.
Totally agree. There is no need to import an entire submarine. In any event by going the HEU route, Naval Group will not be of much use. Naval Group (DCNS) will be very hungry after the Australian reversal. Get specific equipment/components and consultancy from Naval Group e.g. Thales supplies the sonar for the Barracuda class, Naval Group itself is developing the F21 HWT. Use DCNS consultancy to retain the VLS, they are used on the Barracuda for housing naval versions of the SCALP as well as Exocet. Torpedoes plus cruise missiles will make the Indian SSN, a true attack submarine.
Cain Marko
BRF Oldie
Posts: 5350
Joined: 26 Jun 2005 10:26

Re: Indian Nuclear Submarines -3

Post by Cain Marko »

So french subs cost an absolutely insane amount. The price escalations in the Aussie deal were written frankly, unbelievable.

Otoh US subs are not available and even if they are, will come at the cost of strategic independence.

No wonder, India went for two Akulas.
Pratyush
BRF Oldie
Posts: 12187
Joined: 05 Mar 2010 15:13

Re: Indian Nuclear Submarines -3

Post by Pratyush »

Barath wrote:SSN has the following needs:...
Hope it is clear.
Last edited by Rakesh on 18 Sep 2021 02:07, edited 1 time in total.
Reason: Sirjee, please do not quote an entire post to put one liners
basant
BRFite
Posts: 889
Joined: 20 Mar 2020 20:58

Re: Indian Nuclear Submarines -3

Post by basant »

CAG should be CBG?
Pratyush
BRF Oldie
Posts: 12187
Joined: 05 Mar 2010 15:13

Re: Indian Nuclear Submarines -3

Post by Pratyush »

They are both correct.
basant
BRFite
Posts: 889
Joined: 20 Mar 2020 20:58

Re: Indian Nuclear Submarines -3

Post by basant »

Thanks!
Rakesh
Forum Moderator
Posts: 18190
Joined: 15 Jan 2004 12:31
Location: Planet Earth
Contact:

Re: Indian Nuclear Submarines -3

Post by Rakesh »

Vicky wrote:Such upgrade does not necessarily require a total redesign of the reactor - Some of the improvements to go from 83 MWt to 120 MWt can be :
1) Higher burnup rated fuel rods- Solvable without foreign help as PFBR already goes to much higher enrichments and burnups of much more energy dense Pu against the less dense U235.
2) New steam generator - Trivial for BARC
3) New turbine - Trivial for BHEL/L&T
4) Reactor pressure vessel modifications and resizing - Solvable at BARC
5) Higher flow rate but silent pumps - Solvable? Probably Yes
Thank you for this explanation. What is the average time we are looking at, of a reactor to be upsized that you have described above?
Vicky wrote:Going much larger than 120 MWt will require a total redesign of every component - every tube, switch, wire, sensor and everything. Time and Money problem - not a technology problem. BARC has already completed design work for the civil 900 MWe/2700 MWt IPWR-900 design and is conducting validation studies for various materials, forgings and equipment before construction approval is given.
The Akula uses a 190MW reactor. Seeing that is the only SSN that the Indian Navy has operated, is it possible that the six SSN P75A program will use a reactor more powerful than 120MW? The P75A is rumoured to be at around 6,000 tons...while the Akula is much heavier at 8,000+ tons. Is 120MW sufficient for a vessel of 6,000 tons and is 190MW overkill? How much time are we looking at to go with a reactor larger than 120 MW?
Vicky wrote:BARC can go LEU if they want and SDB can simplify the refueling system by adding a hatch to the design. It's not a reactor design problem but a hull integrity design problem. Ball will be in the Navy's court - BARC probably won't face any hurdles.
When you say ball will be in the Navy's court, I am reminded of the spat between the Navy and BARC over the reactor for IAC-2. Both sides wanted each other to fund the development of the reactor. So when you say ball will be in the Navy's court, I am assuming you mean money?
Vicky wrote:BARC is also certainly capable of going 90%+ HEU and go the full packaged 25 year 0-refuel design. They will need to redesign the fuel rods to handle higher burnup and higher temperatures. BARC has solved most of these high burnup/high temperature problems in it's R&D for PFBR (albeit for plutonium) and have also designed fuel rods for this. BARC is also planning to solve this problem anyway with TRIGA fuel for IHTR program.

BARC IPWR-900 avg fuel burnup (5% U235 LEU) - 30 MW · day / kg
IGCAR PFBR avg fuel burnup ( 27.7% PuO2) - 134 MW · day / kg

The only problem is - Enrichment for 90%+ HEU will take up a lot of cascades in the enrichment facility and will require significant capacity upgradation at the proposed new facility. Since no foreign country will either supply LEU or HEU for military purposes since we are non-NPT - fuel has to be local and will take up enrichment capacity anyway.
This jingo is khush to read the blue highlighted bit. So a big thank you for this.

Can you please explain in more detail the highlighted portion in red? I am basically looking to find out whether the capacity upgradation is a funding issue or some other issue.
Vicky wrote:The capacity increase required to go from the existing around 15% in arihant to 90%+ is marginal as the graph of Separative Work Units vs U235 % looks like below. It's much harder to make 5% LEU but incrementally pretty easy to take the step from 5% to 15% and much more easier to go to 90%.

Natural to 5% - A lot of work required - 900 SWU//tonne of NU
5% to 15% - Add 200 more SWU - 1100 SWU/tonne of NU - Arihant is probably here
90% - Add 150 more SWU - 1250 SWU/tonne of NU

Let's not bother with refueling every 5 years instead of going full HEU by adding small amount of enrichment capacity. LEU should only be considered if BARC is not confident about it's capability to go HEU (unlikely) or Navy is okay with cutting open subs every 10 to 15 years (marginally likely).

Only the non proliferation ayatollahs are pitching for all countries including US to go LEU so that some they can allegedly sleep happy that the material won't be diverted for a weapons programme. Useless virtue signalling exercise that doesn't add any value for a non-rich non-superpower country like us and we already have nukes.
Is it feasible to upgrade the 83MW reactor on the Arihant to 90% by adding more SWU? What work is involved in doing this? And how long will the boat be out of commission?
Vicky
BRFite -Trainee
Posts: 79
Joined: 23 Aug 2021 19:33

Re: Indian Nuclear Submarines -3

Post by Vicky »

Rakesh wrote: Thank you for this explanation. What is the average time we are looking at, of a reactor to be upsized that you have described above?
2 to 3 years from Day 0 of design and validation work for BARC and then handed over to NPCIL/BHEL/L&T crew for construction as per standard timelines. Standard shore and sea trials timeline.
The Akula uses a 190MW reactor. Seeing that is the only SSN that the Indian Navy has operated, is it possible that the six SSN P75A program will use a reactor more powerful than 120MW? The P75A is rumoured to be at around 6,000 tons...while the Akula is much heavier at 8,000+ tons. Is 120MW sufficient for a vessel of 6,000 tons and is 190MW overkill? How much time are we looking at to go with a reactor larger than 120 MW?
Akula is huge. I think we should be looking at Barracuda-class as a comparison at 5400T at 150 MWt with speed 25 knots+. Seawolf is also a good comparison (34 MW shaft means approx 150 MWt at 20 knots, 8000T). If we do 120 MWt we might do 18 to 20 knots (I forgot the equations but some goolging around will give you the relationship between dispacement, shaft power and speed), if we can get to 150 MW we should be on-par with Barracuda and Los Angeles. Forget the 190 MW Akula type.
Navy might need to tone down it's VLS or SSGN aspirations at this stage and shelve it for future generations of SSNs to stay with 6KT limit.
When you say ball will be in the Navy's court, I am reminded of the spat between the Navy and BARC over the reactor for IAC-2. Both sides wanted each other to fund the development of the reactor. So when you say ball will be in the Navy's court, I am assuming you mean money?
What I mean is that Navy on behalf of it's own SDB/DND should decide if they are capable of designing a pressure-safe removeable hatch on the pressure hull. For funding, MoD paying is the honorable way for the SSN. If it was the SSBN, the SFC/DAE budget makes sense. It's just finger-pointing and buck-passing.
Vicky wrote: The only problem is - Enrichment for 90%+ HEU will take up a lot of cascades in the enrichment facility and will require significant capacity upgradation at the proposed new facility.
Rakesh wrote: Can you please explain in more detail the highlighted portion in red? I am basically looking to find out whether the capacity upgradation is a funding issue or some other issue.
Only a funding issue. DAE were asking for funding to build the newfacility since 2011. They only seem to have got the funds in 2019/2020 as Google earth shows the construction has finally started.This capacity is probably mainly for the civilian IPWR-900's but ofcourse can be utilised for Navy till they come online if the need arises.

they also added more buildings at the older site seeming to indicate they are already increasing capacity 3 to 4x. Whether this capacity is sufficient for 30-year lifespan SSN's is unknown and making it sufficient is only a funding/decision problem.
Is it feasible to upgrade the 83MW reactor on the Arihant to 90% by adding more SWU? What work is involved in doing this? And how long will the boat be out of commission?
Not feasible with a reactor already irradiated (contaminated) with radiation as modification to fuel layout, upgrading flow/pressure rating in the coolant lines, upgrading radiation contaminated steam generator etc. will require humans to cut open highly radioactive irradiated components from the exposed side. Not possible.
Only possible in new build reactors.
Pratyush
BRF Oldie
Posts: 12187
Joined: 05 Mar 2010 15:13

Re: Indian Nuclear Submarines -3

Post by Pratyush »

Vicky, good series of informative posts.

Jut one confusion.

The USS Enterprise when commissioned had reactor crores that had to be upgraded in the first half of her service. The uranium initially used was low enriched. However, during the later part of her service. She was using highly enriched uranium.

If we could understand how that was done.

Perhaps our solution could be in the same direction.
Barath
BRFite
Posts: 474
Joined: 11 Feb 2019 19:06

Re: Indian Nuclear Submarines -3

Post by Barath »

ldev - let's agree to disagree.

I believe the Indian Navy has in its sights the possibility of much larger area of operation, that even conventional carriers can & do use a burst of speed for tactical reasons (eg getting air over wings for planes to take off, making location harder), that tailing a submarine is fallible, (especially as sub tech advances, and China devotes newer subs and more resources), and that even if you do trace/tail a sub, being able to kill it between the start of launch prep and the launch of the last SLBM requires high speed. That's a few hundred thousand to several million lives depending on that.

Trying to go all-in that speed is not required, that combat will only be at low speeds, and that all opposing subs will be traced over the next 30-40 years (lifetime of a sub + predecessor time) is a mug's game. You do not want to stake all on that gamble. . https://core.ac.uk/download/pdf/36725639.pdf -

@vicky : If I understand correctly, there is not a 1:1 relation between power and displacement/speed, since cross-section and wetted area also play into drag; since reactors don't always come in one form factor and there are other considerations, a nuovo design of a sub and its power/propulsion are closely inter-related. (cf: Conform vs LA class; Alfa class )

Reactor design and HEU %age also play into time between re-fueling/overhaul, which is a significant driver of cost and availability. Thus trading off for increased life/time to refuel should also be considered. @vicky has suggested some of these

A few considerations : S5 SSBN will be a giant, at over twice the size of Arihant, larger than Akula , having to hold large ballistic missiles (large height/dia). While a SSBN may not have the same needs for high speed, I would expect that this S5 needs a new reactor, the Arihant 83Mwth design simply may not suffice.

Obviously, the SSN will also need reactors. There is significant potential value in having VLS/long range cruise missiles (See also 75i), so I figure the IN would push back against deleting them, even for potential cost savings

You can look at upgrade or a new design. And if there can be one common design for both. [ Any thoughts, @vicky ? ]

A good practice for a new (clean sheet) design is to have a land based prototype (See also S1 in Kalpakkam, and the US reactors in Niskayuna) to prove it out. Might not be as necessary for an uprate. Having multiple clean sheet new designs/prototypes may be overkill.
Post Reply