Merits and Demerits of All-nuclear submarine force

A nuclear-powered submarine is propelled by a small nuclear reactor on board the vessel. At present, India has only one commissioned nuclear-powered submarine, INS Chakra. Even though there are several advantages of a nuclear submarine, it doesn’t make sense to go for a submarine force in which all of them are nuclear-powered; rather a mix of diesel and nuclear submarines makes more eminent sense for the Indian navy.

At present, only three navies in the world have an all-nuclear submarine force – US, UK and French. This capability contributes significantly in making them among the most powerful navies in the world.
The most crucial advantage of a nuclear submarine is that it does not have to stop for re-fuelling as opposed to conventional diesel submarines, and its operational time in sea is only limited by the endurance of its crew and supplies. Thus, it can be submerged and deployed for operations almost endlessly. A nuclear submarine can also travel twice as fast as a diesel one.
However, the major limitation of a nuclear submarine is its high cost of acquisition, which is almost double than that of a diesel sub. Even if India plans for building indigenous nuclear submarines, it doesn’t have the technological capability to build very powerful nuclear reactors which can propel the submarines at high speed and power. Thus, India will have to depend on imports of nuclear submarines which will make a big hole in India’s already weak finances.
To evaluate whether India needs an all-nuclear submarine force, it is important to understand the functions of submarines and also their specific uses in peacetime and wartime in India’s context. The role of a submarine in peacetime includes surveillance operations, information gathering, and acting as a deterrent. In wartime, it can act also play additional roles such as launching attacks on enemy land, warships, merchant ships, and submarines. It can also be used for landing of special operations forces.
India faces war threats mainly from Pakistan and China. For naval warfare against Pakistan, which is at a close distance to India, the operational period of a few days provided by diesel powered submarines is sufficient to successfully fight enemy warships, launch attacks on land, or block Pakistan’s major ports such as Karachi. Moreover, diesel submarines can be fitted with Air Independent Propulsion (AIP) system to increase the time they can stay submerged without surfacing for recharging batteries. However, naval warfare with China will demand submarines that can stay submerged for longer periods and also run longer without the need for refuelling, due to the larger distances involved. Indian submarines might also have to operate in the South China Sea. For such missions, nuclear submarines will be without doubt the preferred choice.
During peacetime, India has no plans to project its power in other maritime zones, like that done by US presently and both US and Soviet during Cold War. The primary areas of operation of our submarines are likely to be in the Indian Ocean, Arabian Sea and Bay of Bengal. One of the Indian Navy’s fundamental tasks also involves the establishment of sea control to protect its vital Sea Lines of Communications (SLOC) and chokepoints such as Strait of Hormuz, Bab El Mandeb, and the Malacca Straits in these areas. For such capabilities, a mix of diesel submarines augmented with AIP systems, and nuclear submarines should serve India’s purpose.
Considering the limitations of high costs of acquiring nuclear submarines and the important yet modest needs of Indian navy, it would be appropriate for India to operate a mix of diesel and nuclear submarines. That said, India should without doubt consider acquisition, through purchase or lease, and even indigenously develop more nuclear submarines than the current single nuclear sub.