Costs and capabilities are among the top reasons for partnering with the United States and the United Kingdom, despite Australia’s lack of experience with nuclear technology.

The recent trilateral announcement by Australia, the United Kingdom, and the United States on forming a new security partnership (called AUKUS) turned heads both because it was unexpected and because of what the agreement entailed: Australia going nuclear.

Although officials from all three countries were adamant that Australia would forgo nuclear weapons and opt instead for nuclear-powered submarines, the pronouncement caused some head-scratching. Why would Australia—a country with a tiny and rather old submarine fleet and no nuclear experience—decide to go all-in on nuclear submarine design? The answer is essentially two-fold: because of the high cost to replace Canberra’s conventionally-powered submarines with a new but essentially similar design and due to the marginal increase in capabilities that replacement would offer.

Collins-class

Australia currently operates a small fleet of six Collins-class submarines. The subs are essentially an enlarged variant of Sweden’s Västergötland-class, a Cold War-era class of diesel-electric submarines. Though the Australian submarines have been in service since 1996, the Collins-class is riddled with problems.

Australia decided to purchase a proven, off-the-shelf design as a cost-saving measure rather than building a new class from scratch. But in deciding to modify the Västergötland-class however, the Royal Australian Navy was essentially creating a new submarine design from the ground up, creating myriad problems.

The Royal Australian Navy discovered defects in the Collins-class hull welding that compromised the submarine’s hull strength. In addition, the submarine’s elongated hull design was not adequately evaluated for hydrodynamic noise before construction and was found to be excessively loud when sailing at high speed. Problems with the submarine’s propeller design, propeller shaft gaskets, and seawater ingestion by the sub’s diesel engines also required a redesign.

Attack-class

To replace the Collins-class, Canberra selected the French-designed Attack-class. But like the Collins-class, the Attack-class submarines are based on a different submarine design, the Barracuda-class subs. This choice could create issues similar to those experienced with the Collins-class, extensively modifying an off-the-shelf design to make what is, in essence, a from-scratch design.

And compared to the Collins-class, the Attack-class would not have offered much of a capability boost. Advantages in range and endurance over the older subs were simply by nature of the Attack-class’ larger size: they held more fuel. And like the Collins, the French submarines lacked a vertical launching system for launching cruise missiles. Lastly, ballooning costs also played a factor. Despite initial French price estimates, costs for the Attack-class ballooned to $90 billion AUD, or nearly $66 billion U.S. Dollars, and would have been Australia’s most expensive defense program.

A Wise Choice?

The Australian move to jump head-first in nuclear-propelled submarines is a smart choice. Not only do nuclear submarines offer vastly superior range and endurance than conventionally-powered submarines, but they’re also much quieter and more challenging to detect and therefore more survivable. Moreover, leveraging the combined 125 years of British and American experience with nuclear submarine propulsion will kick-start the Australian program. Though details on what exactly their eight new nuclear submarines will look like exactly are not yet known, there is a good chance they’ll be broadly quite similar to an existing American or British design.

Caleb Larson is a multimedia journalist and Defense Writer with The National Interest. He lives in Berlin and covers the intersection of conflict, security, and technology, focusing on American foreign policy, European security, and German society.

Image: Reuters