UK’s Astute Nuclear Submarines: The UK Ministry of Defence has awarded a £12.5 million ($15.5 million) contract to the French Naval Group for the supply of four additional Fresh Water Cooling Heat Exchanger (HEATEX) units. These systems are critical for cooling the reactors and auxiliary systems on the Astute-class nuclear-powered attack submarines operated by the Royal Navy.
The HEATEX units will be manufactured to an improved specification and are being sourced from Naval Group due to their bespoke design and the company’s exclusive access to the technical drawings and specialist tooling needed for production. This contract follows a previous agreement in 2024 for two similar units.
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UK’s Astute Nuclear Submarines
The Astute-class submarines form a key component of the Royal Navy’s fleet. Currently, five of these advanced vessels are in service: HMS Astute, which was commissioned in 2010; HMS Ambush in 2013; HMS Artful in 2016; HMS Audacious in 2020; and HMS Anson in 2022.
Two more submarines in this class, HMS Agamemnon and HMS Agincourt, are progressing through construction and pre-sea trial phases at BAE Systems’ facility in Barrow-in-Furness. Despite a fire incident at BAE Systems’ Devonshire Dock Hall in October 2024, which caused local safety concerns, submarine production schedules were not immediately affected. The cause of the fire remains undetermined.
According to Naval technology, The Astute-class submarines are powered by the Rolls-Royce PWR 2 pressurized water reactor. This system features a full-life core, eliminating the need for refueling throughout the submarines’ operational lifespan. The propulsion system is highly advanced, combining Alstom turbines with a Rolls-Royce pump-jet propulsor and additional support from diesel alternators, an emergency drive motor, and a retractable auxiliary propeller. The onboard systems also include an MTU 600kW diesel generator and a digital control system from CAE Electronics for steering, diving, and depth management.
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The PWR 2 reactor was originally developed for the Vanguard-class submarines and enables Astute-class vessels to travel extensive distances without refueling—up to 20 times around the globe under current capabilities. Future technological advancements are expected to extend this range to over 40 global circumnavigations.
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The reactor relies on sophisticated components, including pressure vessels from Babcock Energy, coolant pumps from GEC and Weir, and instrumentation from Siemens Plessey and Thorn Automation.
This investment in HEATEX units and the continued development of the Astute-class submarines demonstrate the UK’s commitment to maintaining a robust and technologically advanced naval capability.
