Indian nuclear submarines

Discussion in 'Indian Navy' started by nitesh, Feb 12, 2009.

  1. shuvo@y2k10

    [email protected] Senior Member Senior Member

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    That 30 year 24 submarine plan was conceived in the vajpayee time. The plan at that time was to purchase half western submarine and rest half Russian submarine s so that MDL has gained expertise on both stealth and endurance technology of both design philosophy. After that we would have gained sufficient expertise for design and development of indegeneous diesel electric submarine. That was the plan.
    But things didn' t go as per plan. Firstly the scorpene class got excessively delayed. Secondly we developed our own indegeneous nuclear submarine arihant.
    Hence on the nuclear front our plan is 4-5 arihant class ssbn and 6 SSN . on diesel electric front we have p75i project of inducting 6 foreign submarine. After that we will have our indegeneous design.This process is likely to be completed in the next 10-15 years. The 30 year plan is a relic of the past.
     
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  2. Kshithij

    Kshithij Regular Member

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    There are 2 types of reactor - PWR (PHWR) and LWR.

    PWR reactor can work in both in Raw uranium as well as enriched uranium - from LEU to HEU. India prefers PWR (or PHWR) reactors as they are efficient plutonium producers and also produce energy as efficiently as LWR reactors. One can simply feed the natural uranium without any enrichment and obtain energy as well as plutonium in this reactor. PWR reactors can also be refueled without shutting them down. The only reason to shut down PWR is for maintenance. These reactors are also compact in nature. But, due to their pressurised way of working, they can't be expanded to 1GW or above easily and will need special precautions to contain pressure

    LWR uses only enriched uranium and can't work in natural uranium. These reactors can work in LEU as well as HEU and produces reactor grade plutonium, not weapons grade plutonium. The plutonium is produced more slowly and have higher content of Pu240 which is not desirable. These reactors also need to be stopped while refueling.

    Overall - PWR reactor is the best reactor for weapons purpose. LWR reactor is scalable and hence more cheaper for energy production. PWR reactor is also compact making it best suited for submarines, carriers etc.

    Now, about usage of LEU or HEU depends on the needs. HEU will mean longer time for refueling while LEU will need short time for refueling. Enriching Uranium is a technology which India, Pakistan, North Korea and pretty much all nuclear countries have obtained. Even Iran was enriching Uranium. I don't understand why some people are shouting that costs will be higher. In case of submarines, the reactors are tightly enclosed and refueling is a big deal. So, the best way to save costs is to get HEU which will last much longer and generate more power for a smaller size.

    Enrichment is an easy process. It is the opening of submarine to refuel that increases cost. So, best way to save cost is to use HEU which lasts in excess of 10 years in almost all cases. For example, a 40% enriched Uranium has over 55 times more uranium 235 than an unenriched raw uranium of same weight

    India also has 2lakh tons of Natural Uranum. Setting aside 1000-2000 tons for a few dozen nuclear submarines is not a big deal

    USA carriers run on HEU. Also, weapons and defence equipment like submarine, carriers don't come under civilian sector but are military. If Uranium is anyways used for defence, what is the point of making such useless treaties? Who will care for them? India also has disagreed. Pakistan, however has been vociferous in opposition. Also, plutonium production is from non-enriched uranium in PWR reactor as I have mentioned above. This is the best way of producing plutonium. For every y150ton of raw uranium of 0.71% U235, a quick run will give 300kg of Plutonium with 0.6% of U235 still remaining. This can be further enriched to 0.71% to run again. Total of 2 ton plutonium for every 150 ton natural uranium can be obtained by this manner. HEU is mainly used for hydrogen bomb's second stage. Plutonium is for atom bomb only.

    We may be using the same technology as Akula whereby there are 2 cases for the submarine (2 hulls). The outer hull and inner hull are 2 layers to increase strength of submarine and protect it in case of accidents (like INS Chakra where only outer hull was damaged) as well as provide stealth.
     
    Last edited: Dec 2, 2017
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  3. Screambowl

    Screambowl Senior Member Senior Member

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    If the NU (natural uranium ) is costly and say it's 0.3% u235 then more NU is required for 1kg of LEU and just 5 separative work unit.
    If NU is costly then 0.2% of u235 is allowed with lesser NU but more number of separative work unit .

    Which over all effects the cost and this is much managable than HEU.

    And LEU is basically considered safe to handle than HEU.
     
  4. Akshay_Fenix

    Akshay_Fenix Member Senior Member

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    Sir ji, our aim is not global dominance but only the protection of Indian Ocean.
     
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  5. Kshithij

    Kshithij Regular Member

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    Natural uranium is not costly. Second, it is 0.71% U235 as isotopes are generally constant. The purity of ore is different from isotope percentage.

    Natural uranium is restricted in international sale. It is not costly. Defence related sales are not permitted. Cost of natural uranium is 50 dollars a kg in international markets.

    Cost of uranium doesn't even matter as opening the submarine and refueling is costly. HEU is not dangerous in terms of radioactivity. Half life of U235 is 700 million years. As a result, its decay is very slow to cause any harm.
     
  6. Kshithij

    Kshithij Regular Member

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    Why are you restricting the objectives?
     
  7. aditya10r

    aditya10r Mera Bharat mahan Senior Member

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    Sir ji,Pakistan will have 13+ subs by next decade,Chinese will have atleast 2 active submarine bases in the IOR.

    We simply cannot counter that big force with only 24 submarines-we need more if we wish to dominate choke points.

    __________________________________________

    Thankfully our geography permits us to do sea denial,but for total sea control we need more subs.

    __________________________________________
     
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  8. Screambowl

    Screambowl Senior Member Senior Member

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    It does matter.
    because enrichment depends on amount of required and amount of depleted required. The separative work unit increases when amount of depleted uranium required is decreasing.

    And the SWU depends on how much DU you want. Thus the cost factor comes in. As how much work you put for 1 kg of LEU

    The above 0.2% and 0.3% is no the NU but DU. ( depleted Uranium)

    The cost factor to LEU to HEU enrichment is lesser than HEU to LEU down blending. So they keep it to LEU.

    Even in USA they had surplus of HEU so they downblended it for power generation which was very expensive. Because you normally don't want a Hiroshima inside a nuclear reactor or some one stealing it.

    More over HEU has high reactivity hence neutron poison is intentionally inserted to reduce the reactivity for neutron absorption.

    The half life of 70% HEU is may be 420million years but even small dose of reaction can cause unwanted damage. And HEU is more critical and reactive in the reactor core.

    Althought Naval rectors may use HEU due to compact size of the reactor and more power required but then since for India it is beginning they should first trained them on LEU before they shift to HEU which will be more complicated.

    You see it's more complicated.
     
    Last edited: Dec 3, 2017
  9. Kshithij

    Kshithij Regular Member

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    Depleted Uranium is defined as less than 0.3% U235 but that is because the reactor waste is considered as depleted uranium after separation. India doesn't even waste that amount of Uranium and uses almost completely. Depleted Uranium is just U238. Depleted Uranium is not used in most cases as fuel but in place of lead to make bullets and ammunition. The requirement of depleted Uranium is not common and not something that people consider before enrichment

    The cost is obviously higher for making HEU but that cost is still small enough. A cost of 1-2 crores are generally ignored as small when compared to other costs. So, the HEU hardly increases any cost.

    HEU obviously has high reactivity and hence provides power for longer duration with limited quantity. In compact machines like submarines, carriers, it is this compactness that matters.

    HEU is less efficient than LEU for energy production in terms of Natural uranium usage and hence it is almost always LEU which is used in generating power in land-based reactors. In reactors, even the U238 is converted to plutonium and then this plutonium also fissiles. So, by keeping LEU, we can harness part of the U238 to get energy instead of wasting it by using it for ammunitions.

    India is not using nuclear reactors for the first time. India has experience since 1956 when first reactor was set up of 1MW. India has been continuously gaining experience. Only a foolish country will use LEU reactors in submarines. LEU reactors may be more efficient per unit of Natural Uranium, but inefficient when it comes to per unit mass of fuel feed and hence incapable of being used in a compact space of submarine
     
  10. singh100ful

    singh100ful Regular Member

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    Russian consultation will be taken.

    The design of the submarines will be of russian origin, so a higher level of stealth will be achieved
     
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  11. nongaddarliberal

    nongaddarliberal Regular Member

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    So should we expect something as silent as the akula class that we have, or will the Russians help us make something close to Yasen class? Akulas stealth profile is already a little behind the curve compared to the latest subs.
     
  12. Kshithij

    Kshithij Regular Member

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    Russians may not help in anything. It is just consultation and not ToT. Though, ToT may be done behind the back. Only time can tell
     
  13. Flame Thrower

    Flame Thrower Regular Member

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    By the way, where does our Arihant stand in terms of stealth!?
     
  14. Kshithij

    Kshithij Regular Member

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    It is classified. Though, I have heard that Arihant is an intermediate between SSN and SSBN. The SSBN and SSN may be just branching of Arihant.
     
  15. Flame Thrower

    Flame Thrower Regular Member

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    I didn't asked about the capabilities.

    Chinese subs are considered to be Romeo class equivalent in terms of stealth.

    I understand that Arihant's stealth is closely guarded, but you know rough estimates would be great.

    Since we'll know the capabilities of one of the quietest ssk (scorepene). Noise reduction techniques might be useful in future SSNs. Experience on Akula will come in handy.
     
  16. Kshithij

    Kshithij Regular Member

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    Ok, some rough details - Arihant is most likely having dual hull like the akula. All items and equipments are within the inner hull. This gives added protection as well as reduces vibration.
     
  17. Screambowl

    Screambowl Senior Member Senior Member

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    No one is aware of what kind of reactor is installed on the sub. If it's the PWR or AHWR with low concentration of U233. But then if they are doing so then it's a mixed reactor of U235 LEU + U233 mutated from thorium. As U233 is risky.

    Honestly I have no idea what they are upto. Well to my understanding it's the cost factor and training.
     
  18. Kshithij

    Kshithij Regular Member

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    Why will anyone use U233? Why would India or anyone put in extra effort yo get U233?

    What training or cost factor? Can you elaborate?
     
  19. Screambowl

    Screambowl Senior Member Senior Member

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    Because that's the way Th cycle works in Th based reactor.

    India has less quantity of U235 so obviously for India it will be costly. And since India is working on it's own reactors so looks like they are training the crew on this AHWR with LEU + Th

    It could be vast it's all presumptions. No one would actually know what they are upto.
     
  20. delbruky

    delbruky Regular Member

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    Is there vacuum between the two inner hulls?, is there is an onboard vaccum pump to regulate vacuum?
     

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