- Rolls-Royce PWR 2 reactor
- MTU 600 kilowatt diesel generators
- Thales Sonar 2076
- Atlas DESO 25 echosounder
- 2 * Thales CM010 optronic masts
- Raytheon Successor IFF
- 6 * 21 in (533 mm) torpedo tubes with stowage for up to 38 weapons:
- Tomahawk Block IV cruise missiles
- Spearfish heavyweight torpedoes
The Astute class is the latest class of nuclear-powered fleet submarines (SSNs) in service with the Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Maritime – Submarines at Barrow-in-Furness. Seven boats will be constructed: the first of class, Astute, was launched by Camilla, Duchess of Cornwall, in 2007, commissioned in 2010, and declared fully operational in May 2014. The Astute class is the replacement for the Trafalgar-class fleet submarines in Royal Navy service.
The Astute class has stowage for 38 weapons and would typically carry a mix of Spearfish heavy torpedoes and Tomahawk Block IV cruise missiles, the latter costing £870,000 each. The Tomahawk missiles are capable of hitting a target to within a few metres, to a range of 1,000 miles (1,600 kilometres). The Astute Combat Management System is a new version of the Submarine Command System used on other classes of British submarine. The system receives data from the boat's sensors and displays the results on command consoles. The submarines also have Atlas Hydrographic DESO 25 high-precision echosounders, two CM010 non-hull-penetrating optronic masts—in place of conventional periscopes—which carry thermal imaging and low-light TV and colour CCD TV sensors. The class also mounts a Successor IFF system.
For detecting enemy ships and submarines, the Astute class is equipped with the sophisticated Sonar 2076, an integrated passive/active search and attack sonar suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 is the world's best sonar system. All of the Astute-class submarines will be fitted with the advanced Common Combat System.
The boats of the Astute class are powered by a Rolls-Royce PWR2 (Core H) (a pressurised water reactor) and fitted with a pump-jet propulsor. The PWR2 reactor was developed for the Vanguard-class ballistic missile submarines and has a 25-year lifespan without the need for refuelling. As a result, the new submarines are about 30 per cent larger than previous British fleet submarines, which were powered by smaller-diameter reactors. Like all Royal Navy submarines, the bridge fin of the Astute-class boats is specially reinforced to allow surfacing through ice caps. These submarines can also be fitted with a dry deck shelter, which allows special forces (e.g. SBS) to deploy whilst the submarine is submerged. More than 39,000 acoustic tiles mask the vessel's sonar signature, giving the Astute class improved acoustic qualities over any other submarine previously operated by the Royal Navy.
A 2009 safety assessment by the Defence Nuclear Safety Regulator concluded that PWR2 reactor safety was significantly short of good practice in two important areas: loss-of-coolant accident and control of submarine depth following emergency reactor shutdown. The regulator concluded that PWR2 was «potentially vulnerable to a structural failure of the primary circuit», which is a failure mode with significant safety hazards to crew and the public. Operational procedures have been amended to minimise these risks.
Astute is the second Royal Navy submarine class, after the Vanguard-class, to have a bunk for each member of the ship's company, ending the practice of 'hot bunking', whereby two sailors on opposite watches shared the same bunk at different times. However, they have less mess-deck space than the Valiant-class submarine built 45 years earlier. Since it is nuclear powered, the boat has theoretically unlimited endurance, though in practice it is limited to 90 days at sea based on food carried (including 18,000 sausages and 4200 Weetabix) and crew endurance.