Explained: The AUKUS agreement to equip Australia with n-subs – About Nuclear Submarines

Synopsis: This article explains the difference between conventional and nuclear-powered submarines. Further also explains India’s nuclear-powered submarines.


Recently a new Trilateral Security Partnership grouping has been formed between the US, UK and Australia (AUKUS) for the Indo-Pacific. As part of this, Australia will acquire nuclear-powered submarines with help from the U.K. and the US within 18 months.

Only a handful of countries possess nuclear-powered submarines. These include the US, the UK, France, Russia, China, and India. With the AUKUS partnership, Australia will also join these elite countries.

Note: India is the only country outside the P-5 (US, UK, France, Russia, China) to possess a nuclear-powered submarine.

Read more: US, UK, Australia form new partnership
What are the disadvantages of diesel-engine submarines?

Conventional diesel-engine submarines have batteries that keep and propel — though not very fast — the vessel underwater. The life of these batteries can vary from a few hours to a few days.

The newer Air-Independent Propulsion (AIP) submarines have additional fuel cells that allow them to stay underwater for longer and move faster than the conventional vessels. However, the fuel cells are used only at strategic times, when the endurance to remain submerged is required.

Both conventional and AIP subs need to come to the surface to recharge their batteries using the diesel engine. However, the fuel cells of AIP can only be charged at on-land stations, not while at sea.

What makes nuclear submarines so important?

A nuclear-powered submarine is classified as an “SSN” under the US Navy hull classification system, wherein ‘SS’ is the symbol for submarine, and ‘N’ stands for nuclear. A nuclear-powered submarine that can launch ballistic missiles is called Strategic Strike Nuclear Submarine or “SSBN”.

The great advantage of a Nuclear-powered Submarine is that its nuclear-powered propulsion gives the submarine a near-infinite capacity to stay dived. Since it is propelled by a nuclear-powered engine rather than by batteries, it does not have to emerge on the surface at all, except to replenish supplies for the crew.

Further, They are also able to move faster underwater than conventional submarines. Added together, these advantages allow a navy to deploy these submarines quicker and at farther distances.

So, they can go long distances without being detected. This provides an option to the country to protect its interests far from its shores.

About the Nuclear-powered Submarines of India

India has had this capacity since it got the Soviet-built K-43 Charlie-class SSN in 1987. It was commissioned with the Red Fleet of the USSR in 1967, and it was leased to the Indian Navy. In India, it was rechristened INS Chakra. The submarine was decommissioned in 1991.

In 2012 India got another Russian SSN on a 10-year lease, called INS Chakra 2.

In the meantime, India was working on building its own SSN, and the first Indian nuclear submarine, the INS Arihant, was commissioned in 2016.

A second Arihant-class submarine, INS Arighat, was secretly launched in 2017, and is likely to be commissioned soon.

India also demonstrated the capability to launch nuclear weapons in 2018, the INS Arihant is now classified as a Strategic Strike Nuclear Submarine or SSBN. This is significant, as INS Arihant completes India’s nuclear triad.

Note: Nuclear Triad means that the country has the capacity to launch nuclear missiles from land, aircraft, and submarine.

Source: This post is based on the article “Explained: The AUKUS agreement to equip Australia with n-subs, and why it has upset France” published in The Indian Express on 17th September 2021.

Print Friendly and PDF