Retired Royal Navy submarine HMS Swiftsure has dry-docked at Rosyth as it prepares for final dismantle in a world first.

The Submarine Delivery Agency (SDA) described the moment as a “milestone”, with Swiftsure set to be the first UK nuclear-powered submarine to be fully dismantled by the end of 2026.

This type of comprehensive dismantling process has not been attempted by any other nation and around 90% of components, including valuable steel, are able to be reused or recycled.

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Swiftsure was part of the Swiftsure-class of nuclear-powered attack submarines that entered service in the 1970s and served for more than 20 years.

The boat is being used as a demonstrator and the task of dismantling it falls jointly onto the SDA and Babcock International, a British defence company that traces its origins to the 19th Century and currently specialises in nuclear engineering.

In contrast, the SDA is a relatively new agency, having been established in 2018, to manage the procurement, in-service support and disposal of UK nuclear submarines.

Nuclear submarines are some of the most complex equipment in the world, according to the SDA.

Dismantling nuclear submarines is an intricate process involving stages like defuelling the reactor, removing radioactive components, and segmenting the vessel.

Ensuring radiation is contained relies on strict safety measures and radiological surveys, while proper waste management, recycling, and international agreement compliance are essential to tackle environmental and security issues.