Artist's rendering of the future INS Aridhaman. Diagram courtesy Indian Defence Research Wing (IDRW)
The following is partly based on Ghalib Kabir's comments of 28 to 29 August 2017 mixed with Pete’s research.
India's future SSBN INS Aridhaman has been under construction at the Ship Building Centre in Visakhapatnam since 2011. Aridhaman might be symbolically launched in late 2017. Actual launch (into the water for fitting out) may be in 2018. Then would follow harbor trials and sea trials for 2 years with commissioning expected sometime in 2020 or 2021.
Aridhaman is the second in the Arihant class and is larger than INS Arihant. While Arihant only has 4 large launch tubes Aridhaman has 8 making Aridhaman more useful as an SSBN. Each launch tube will be able to carry 3 K-15 Sagarika missiles (total of 24) with a range of 750 km or a total of 8 future K-4 missiles (with a range of 3,500 km)
Aridhaman length and displacement will increase due to the 4 extra launch tubes, a longer more powerful reactor, extra crew, more powerful sonars and other mission critical equipment. Aridhaman may be 125m long and 7,000 tonnes (surfaced) larger than INS Arihant’s 111m and 6,000 tonnes (surfaced). Aridhaman's dimention would be very similar to the no longer operating US Ethan Allan class (at 125m long/7,000 tonnes).
Aridhaman will have one seven-blade propeller powered by a PWR reactor. INS Arihant has a 83 MWt (12 MWe, 16,000 shp) reactor while Aridhaman may have a 100 MWt reactor (approx 16 MWe or 20,000+ shp)
The increase in power of Aridhaman's 100 MWt reactor may be achieved by many means including:
- larger size
- higher HEU than the usual 40% for Indian nuclear subs (see page 67 of this pdf) and
- higher steam pressure
If the reactor heavily relies on Russian design assistance then Russia’s VM-4 reactor (70-90 MWt) may be an influence. Alternatively India's advanced nuclear complexes (especially that at Kalpakkam) might have allowed India to develop the 100 MWt reactor without Russian help.
Another INS Aridhaman image (courtesy Defense News).