Right now, theres at least one nuclear-power, nuclear-armed submarine stealthily patrolling the waters off the UK. The sub is powered by a nuclear reactor, so it can cruise undetected for over 20 years without refuelling. Oh, and its also armed with eight nuclear warheads each six times more powerful than the atomic bomb dropped on Hiroshima.Since 1969, the Royal Navy has kept at least one of these fission-powered submarines in the water at all times. The vessels are the backbone of Britains nuclear deterrent and send a giant warning to other nations who might get funny ideas.Rolls-Royce today announced that it has secured a whopping 9bn contract to maintain and upgrade the Navys submarine nuclear reactors. Under the deal, the British engineering firm will also build reactors for the UKs new class of nuclear-powered subs.The Royal Navys submarine fleet is split between Astute-class attack submarines (SSNs) and Vanguard-class ballistic missile submarines (SSBNs). The Astute-class are nuclear-powered but conventionally armed. Six of seven planned vessels are already operational. The Navy eventually plans to replace the Astutes with SSN-AUKUS submarines, the result of a collaboration with the US and Australia.Limited tickets available - Book NowMeanwhile, the Vanguard class, which first entered service in 1994, forms the backbone of the UKs nuclear deterrent, carrying Trident II D5 nuclear missiles. The Navy plans to replace the Vanguards with the Dreadnought-class SSBNs in the early 2030s.Under the so-called Unity contract, Rolls-Royce will design, manufacture, and support the new subs pressurised water reactors (PWRs). These machines use uranium to generate heat, turning water into steam that spins a turbine to generate electricity. The steam then cools, and the process repeats.The Unity deal is the largest Ministry of Defence deal Rolls-Royce has landed in its 121-year history. Predictably, the UK government is celebrating the new contract as a win for national security and job creation.National security is a foundation of our governments plan for change, and this is a clear demonstration of our commitment to the UKs nuclear deterrent, which is our ultimate insurance policy in a more dangerous world, said the defence secretary, John Healey.The contract is expected to create more than 1,000 UK jobs and safeguard 4,000 other roles. Story by Sin Geschwindt Sin is a climate and energy reporter at TNW. From nuclear fusion to escooters, he covers the length and breadth of Europe's clean tech ecos (show all) Sin is a climate and energy reporter at TNW. From nuclear fusion to escooters, he covers the length and breadth of Europe's clean tech ecosystem. He's happiest sourcing a scoop, investigating the impact of emerging technologies, and even putting them to the test. Sin has five years journalism experience and holds a dual degree in media and environmental science from the University of Cape Town, South Africa. Get the TNW newsletterGet the most important tech news in your inbox each week.Also tagged with