How much power do nuclear subs use?

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We take a look at some of the most demanding naval vessels to see just how much nuclear power they produced:  the first nuclear submarine, the largest sub, and the latest development in aircraft supercarriers.

Free from the limits of conventional power

The switch from diesel-electric power to nuclear-powered submarines completely removed the need for air in propulsion systems.  That meant that, whereas conventional subs could only stay submerged for a matter of hours or days, nuclear ones could theoretically stay under for years. Just as long as the crew had enough to eat.

So it’s no surprise that the world record for the longest underwater patrol is held by a nuclear submarine: back in 1983, the HM Warspite stayed fully submerged and unsupported for 111 days.

Perhaps more amazingly, the average nuclear submarine of today probably won’t even outlive its own fuel reserves. It will be taken out of service before they run out.

Because even the tiniest weight of nuclear fuel can produce a massive amount of energy, many modern subs could operate for 25 years without ever needing to be refuelled.

And that’s still while producing a serious amount of energy: according to the Royal Navy, just one of its Trafalgar-class subs has a reactor that could power the whole town of Swindon.

The first: the USS Nautilus

In 1954, the United States launched the world’s first nuclear-powered submarine, the USS Nautilus.  Named after the famous sub from Jules Verne’s Twenty Thousand Leagues Under the Sea, she had a power output of 10 Megawatts (MW). That’s comparable to some of the smallest UK wind farms and power stations active today.

With her nuclear advantage, Nautilus was able to stay submerged for far longer than any other submarine before. And in 1958, she became the first watercraft to reach the North Pole.

The biggest: the Russian Typhoon

Also known as the Shark class, this nautical monster of the 1980s is the largest class of submarine ever built, with a length of 175 metres and a weight of over 24,000 tonnes.

It was so huge, in fact, that it was powered by two nuclear reactors: a pair of OK-650s with a power rating of 190 MW each. That’s 19 times more powerful as the Nautilus.

Just one of those nuclear reactors – if running continuously at full capacity – could create the same amount of energy as the business electricity supply for around 24,000 average-sized UK companies.

The latest: the Gerald R. Ford aircraft carrier

For a ship to be able to carry up to 90 aircraft and still be able to move, it’s going to need some serious juice behind it.  The first of the latest American series of supercarriers is due to join the fleet early next year, and it’s a monster.

It’s over a thousand feet long and spans 25 decks.  To shift its immense weight of 100,000 tonnes, the US Navy has equipped it with two A1B nuclear reactors, each capable of producing 300 MW of electricity.

But it’s not just about providing the power it needs today.  The tremendous output of its twin nuclear reactors is intended to be future-proof: the US Navy predicts that the Ford-class supercarrier will be an important part of the fleet for the next 90 years.

And, looking back at how the demands for energy have grown in the last 90 years, you can’t really blame them for erring on the side of excess.

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