USS Gerald R Ford Vs HMS Queen Elizabeth - Nuclear vs Non-nuclear

USS Gerald R Ford Vs HMS Queen Elizabeth – Nuclear vs Non-nuclear

In Vehicles, Videos by Paul ShillitoLeave a Comment


The USS Gerald R Ford and the HMS Queen Elizabeth are the latest and most modern aircraft carriers in the world. Both use the latest technology to support planes like the F-35 but why has the British carrier not followed in the footsteps of the American carriers and used nuclear to power it’s systems and what are the pro’s and cons of being nuclear or non-nuclear in a modern navy.

 As the British influence and military budgets shrank after WW2 so did the size and number of its aircraft carriers in the belief that new carriers would be used as part of a larger NATO task force. So the last generation of invincible class light carriers was coming in at 22,000 tonnes, Compared to the US’s Nimitz class which tip the scales at 100,000 tonnes.

The British carriers were built primarily for anti-submarine warfare in the cold war North Atlantic and not for projecting naval power around the world like the US ones.

However, after the devasting Kosovan war of the late 1990s, Europe was seen to have done too little too late to intervein. So a European Union Rapid Reaction Force was proposed that would be able to act on a global level and independently of NATO and the US. As part of this 3 new large aircraft carriers would be built which would share a common design, two by Britain and one by France with other European nations making up the support group.

However things didn’t quite go to plan, the French canceled their carrier in 2013 due to budget restraints and because they thought that the non-nuclear propulsion was a step backward for French technology.

So the British continued alone with the HMS Queen Elizabeth and the HMS Prince of Wales as it was now believed that bigger was better and small carriers just couldn’t provide air superiority quickly, one of a number of lessons learned from the Falklands war.

These are collectively called the Queen Elizabeth Class carriers or QEC and named after a first world war super-dreadnought battleship and not the current Queen of England just in case you were wondering.

Even though the QEC carriers are a bit smaller, they are still the second-largest non-US Navy warships in the world after the WW2 Yamato-class Japanese battleships, displacing 65-70,000 tonnes depending on the final build. They were also to be of an adaptable design that could use either CATOBAR ~ Catapult Assisted Take-Off, Barrier Arrested Recovery or Ski jumps for Short Take Off and Vertical Landing aircraft, in particular, the F-35B Lightning II joint strike fighter.

When the British carriers were on the drawing board nuclear power was looked at as an option. With the right design, it can provide enough power to run the ship without refueling for up 25 years.

Land-based reactors usually produce about 1600MW, marine reactors are a few hundred MW. These reactors have to be very small yet powerful for their size to fit in the limited space of a ship, even one the size of an aircraft carrier

This small size means more expensive materials have to be used that are more resistant to radiation and  that the neutron interaction with fissionable material before it escapes into the shielding is much less. So highly enriched weapons-grade uranium is often used, this increases the power density and extends the reactor lifetime but is much more expensive and a greater security risk.

You also can’t rely on gravity to drop the control rods into the reactor core to shut it down like land-based one because the pitching and rolling motion of the ship in the sea, so mechanical control systems must work flawlessly. This and extra things like the desalination of seawater to make fresh water for the cooling system, all add’s to the cost and make’s it very expensive to build a nuclear-powered ship.

But in recent years there has been a move against nuclear ships with some countries not allowing nuclear-armed or powered ships in their territorial waters and as these are the flagships of the country they represent they are carrying both ecological and political baggage.

The size of the QEC carriers also limits where they can dock and maintenance can be carried out only at nuclear-certified ports. The UK has only two certified X Berths at Devonport and Faslane.

Maintenance requires specialist nuclear technicians and then there is the decommissioning at the end of their working lives. The US has a specialist area at Puget sound for the disposal of their nuclear assets and large areas in remote locations where the remains of the reactors can be buried. The UK has still to complete the decommissioning of a single nuclear submarine.

Although Britain could build nuclear carriers, all its experience is in submarines and not surface ships. The only shipyard set up for assembly of nuclear-powered ships is Rosyth which is booked up with decommissioning old nuclear subs and building new ones. It would also need to bring in a substantial number of nuclear specialists from the US or France at considerable expense as we don’t have enough in the UK.

All this contrasts with the US, where the US Navy is one of the biggest and oldest nuclear operators in the world. It has a huge amount of experience that dates back to the end Manhatten project in the 1940’s.

It has developed 27 different reactor designs that have been used in 219 nuclear-powered vessels and brought over 526 reactor cores into operation. It currently operates 81 nuclear-powered vessels, 11 aircraft carriers and 70 submarines.

It’s clocked up over 6200 reactor years and the nuclear-powered vessels have traveled over 240 million Km without a single reactor accident and it has a safety record that is second to none.

One of the major differences between the new US Ford-class carriers and the previous generation Nimitz class was the introduction of more powerful A1B reactors built by Bectel which are both smaller and simpler to operate, yet generate at least 25% more power than the A1W Westinghouse built reactors in the Nimitz.

The Nimitz class carriers have been in service since 1975 and in that time a lot of new technology has been developed such as the EMALS Electromagnetic Aircraft Launch System as well as many more modern systems requiring an electrical supply. There are also the near-future weapons and defense systems like rail guns, directed energy weapons and dynamic armor in the pipeline all of which will require large electrical supplies, something that the Nimitz class had reached the limits of.

The Ford Class carriers were designed to have at least double the electrical generating capacity of anything they need now to allow for future developments.

The US carriers use steam-power not only to power the turbines for the propellers but also electrical generators and steam catapults to launch the planes, steam being something which the nuclear reactors produce a lot of.

But all the steam plumbing creates a lot of complexity, maintenance, weight, and more manpower to operate and also determines where the reactors are placed.

Whilst steam catapults have proved to be very reliable in the past they have no form of feedback control and as such can transmit very large tow forces that can stress the airframes of the planes especially lighter ones which means more maintenance, cost and aircraft downtime.

So for the Ford Class carriers, the EMALS Launch System was developed. This uses an electric linear motor that uses feedback to accelerate the plane smoothly depending on its weight. Its also lighter and less complex to fit than the old steam ones and with a quicker recharge time should be able to launch more sorties in the same time.

Something which is often talked about it is the unlimited range of nuclear-powered ships. Well, yes they do have an unlimited range but unlike a nuclear submarine which travels alone, a carrier is always accompanied by the carrier strike group of supporting warships which are often non-nuclear.

The planes themselves also require aviation fuel has to be replenished by supply ships along with food, water, and ammunition if extended missions are ongoing.

The Royal Navy has never operated nuclear carriers, so it has always had oilers or fuel replenishment tankers to resupply it’s aircraft carriers as part of their operation. This meant there was much less of an incentive to go nuclear with the new carrier.

The cost of building and maintaining nuclear is higher than running conventional oil powered carriers, even with rising fuel costs factored in. It will take about 15 years before the cost of fuel catches up extra cost of building a nuclear version and that’s without the periodic nuclear refueling costs and the very expensive and problematic decommissioning at the end of their service life.

Old conventional Aircraft carriers are often sold on to foreign powers so some of that money can be recouped, nuclear ships, on the other hand, can not be sold on and become a liability.

About every 25 years or so the nuclear reactors on a Nimitz class carrier have to be refueled which can take it out of service for several years and is usually combined with a major refit and cost’s billions to complete.

The Royal Navy has only a small number of nuclear technicians for its submarine fleet and would struggle to find new ones to look after any new nuclear carriers.

So if nuclear was out what could be used in its place. The solution they opted for was Integrated electric propulsion or IEP with electric motors to drive the propellers, something which is well proven in the commercial shipping sector but still a novel feature in military ships, the new Zumwalt class destroyers in the US navy also uses this type of IEP propulsion.

Using a combination of two Rolls-Royce Marine Trent MT30 36MW gas turbines, basically, a Rolls Royce Trent 800 jet engine mated to a generator and four 11MW Wärtsilä diesel generators, this combined setup can supply up to 116MW of electrical power.

The QEC carriers have twin propellers which are each driven by two 20MW General Electric induction motors.  

The diesel generators provide the baseload supply for normal cruising and when extra speed or power is required the gas turbines are used as well.

As the entire system is electrical, the generators can be anywhere on the ship that is suitable, freeing up space for other uses like aircraft hanger storage.

Both the QEC carriers were designed for the EMALS launch system even though it wasn’t fitted in the end, they still enough power generation to allow it to be retro fitted at some point in the future if required.

Lessons learned from the Falklands War showed that the STOVL Short Take-Off and Vertical Landing Sea Harriers on a light carrier like HMS Invincible could carry out more sorties than conventional aircraft on a larger catapult powered carrier like the Ark Royal as it would have been severely limited due to the bad weather of the South Atlantic if it had been in service as it was scrapped two years earlier.

Instead of using the conventional takeoff F-35C that the US Navy opted for and which are suited to the larger Ford Class with the EMALS launcher, the MOD opted for the F-35B STOVL version which meant the need for catapult and arresting gear was removed and echoed the Falklands experience but now with a full-sized carriers, each with many more aircraft.

A ski jump at the end of the runway requires nothing in the way of power or complexity compared to a catapult but achieves the same result with STOVL aircraft.

So, in the end, the Royal Navy ended up with two of the most modern carriers in the world but without going down the nuclear route, yes it was a cost-cutting measure but then the US defense budget is about $600M to the UK’s $50M and you could have two QEC carriers for the price of one Ford-class carrier with a substantial amount of change and without all the nuclear baggage and long term costs that it entails and do a very similar job.

What do you think of the latest carriers from the UK and the US, let me know in the comments, so thanks for watching and please don’t forget to subscribe, thumb up and share.

Paul Shillito
Creator and presenter of Curious Droid Youtube channel and website

Leave a Comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.