India’s 6,000 tonne INS Arighat prototype SSBN launch on November 19, 2017 is less of a surprise when one considers GhalibKabir’s advice on December 12, 2017 that INS Arihant and another 6,000 tonne nuclear sub (now known as Arighat) were under construction since 2006. Their reactor specifications were apparently frozen at 83MW, meaning they could not be built much larger than 6,000 tonnes - if a cruising speed around 20kt was maintained. India, of course, sees its future SSBNs as the most secure second strike weapon platforms.
Perhaps the need for a continual high level of SSBN budgetary funding prompted Indian SSBN builders to disseminate larger SSBN Aridhaman propaganda for years. Propaganda could also be seen as public relations. As early as July 14, 2014 Aridhaman was to be “launched into water soon”. Submarine Matters as early as August 24, 2014 doubted the ambition of India's SSBN and 6 x SSN programs (SSNs sanctioned in February 2015).
So the non-appearance of a much larger INS Aridhaman SSBN may be due to India’s current inability to produce a reactor much more powerful than 83MW. Another limitation seems to be the immaturity of any 7,000km range SLBM (called K-5 or K-6). So India is not indulging in a rush program to produce a 13,000 tonne SSBN large enough to mount K-6s.
India’s SSBN Program at its most basic seems to have several requirements including sufficient reactor power, SSBN size to accommodate large enough SLBMs to carry a sufficient payload over a sufficient range. More specifically:
A. Develop, test and fine tune 2 x 6,000 tonne prototypes (INS Arihant and INS Agrihat) and
B. launch 2 small 7,000 tonne SSBN by 2022 which will have 8 x (very limited 3,500km range K-4s) 1.3m diameter, 10m long. India, of course, claims to, or does, pursue a No First Use nuclear policy. But if China fired first the medium range K-4 can, once it is ready, reach only a limited number of significant targets within China. These include:
Suspected Chinese IRBM hardened silos and TEL hiding places
The PLA’s Western and Southern Theatre Command HQs and troop concentrations
See Southwest China map for provincial capitals with comparatively large southwest Chinese populations, including:
- Tibet provincial capital Llasa with population about 1 million
- Yunnan provincial capital Kunming with about 7 million people and
- Sichuan provincial capital Chengdu with about 15 million
- Guangxi provincial capital Nanning 7 million
- Guizhou provincial capital Guiyang with about 5 million
For a 7,000 tonne SSBN it is preferable to use a slightly uprated 90 MW reactor. This is possible, assuming 6,000 tonne Arihant of 83MW reactor is a development of the Russian 70MW - 90MW VM-4 reactor. According to Dinesh Kumar, December 30, 2017 "INS Arihant has its limitations...[Arihant's and Arighat's (?)] nuclear reactor has a short refuelling cycle and therefore a limited endurance capacity." If ArHydronamic improvements can be made to the sail/fin and pump jet propulsor or a slower cruising speed may be acceptable.
C. skip the 7,000 tonne SSBNs and go straight to 13,500 tonne SSBNs powered by an Indian-Russian development of Russia’s well used Russia 190 MWt OK-650 reactor. A 13,500 tonne SSBN needs the capability to launch, from Bay of Bengal bastion waters, a true 7,000km intercontinental SLBM with warheads in range of Beijing. Specifically 12 x K-6 SLBMs, 12m long, 2m diameter. A mature K-6 would give India an equivalent capability to China's JL-2 SLBM (with a range up to 8,000km).
Maybe the above US SLBM comparitive image is useful if K-4 can be equated to a light warhead Polaris A2 and the K-6 equated to a Trident I C4. This would mean the K-6 would be over twice the overall K-4 SLBM weight. (Image and broader data is at the FAS website).
SLOW INDIAN SSBN PROGRAM?
I agree with Dinesh Kumar, December 30, 2017 analysis, that India's only operational SSBN Arihant "with a limited missile range compares very modestly with China, which already has about ten nuclear-powered submarines and that too with greater endurance and long-range nuclear tipped missiles, in addition to over 50 conventional submarines. China is expected to increase its submarine fleet to between 69 and 78 by 2020, according to a US Congress report. Both Pakistan [8 future SSKs] and Bangladesh [2 renovated SSKs] have contracted purchase of conventional submarines from China, thus adding to India’s increasing security challenge in the Indian Ocean Region."
India needs to build submarine parity with China by 2040.