Well the RCN had a proposal in the 1960s to refit our Oberon-class SSKs and fit the Iroquois-class Destroyers with a variant of AECs Slowpoke reactor.
It obviously went nowhere, but DND did take a hard look at it.
Have the (borderline-ASB) POD be that they go for it, thus opening the floodgates throughout NATO.
The end result (by the 1990s) would be an RCN that has:
3x Onadoga-class SSN
4x Iroquois-class DDGN
12-20x Halifax-class FFGN
And so on...
Other navies also have nuclear propulsion for the majority of the medium and large surface combatants, and for virtually all of their submarines.
The problem with using a Slowpoke reactor is power. The slowpoke is only rated for 20 kW, which is MUCH too little for a ship power plant, whose needed outputs would be measured in MW. The propulsion system of the OTL Halifax-class frigates, two GE LM2500 gas turbines and a SEMT Pielstick turbodiesel cruise engine, is 42.25 MW at full power, thus you'd need 2100+ Slowpokes to make the power needed for the Halifax-class. This need for power makes nuclear propulsion trickier for smaller vessels, both because of the power need and because of weight concerns.
The S8G reactor, developed by General Electric for the US Navy's Ohio-class missile submarines, is easily small enough to fit in a Halifax-class - 42 feet in diameter and 55 feet long, plus turbines, and it makes 60,000 horsepower (45 MW) in the Ohios, again lots for the purpose. And Ohios can run for over 20 years on a single fueling, and American SSBNs, by virtue of having two complete crews to a vessel (true with every American missile sub since the
George Washington), spends a lot of time at sea. The downsides are that the reactors are expensive, weigh a lot (2,750 tons, over half of a Halifax-class current displacement) and as mentioned in the OP require a lot of extra money spent, both in construction and operation.
To work with the OP in Canada's case, what would probably work best for us would be to continue developing reactors as we did IOTL but follow the Americans' lead for nuclear propulsion on warships. Reactors of the time wouldn't fit on smaller ships, so you call up the biggest non-aircraft carrier ships in the RCN at the time (Minotaur-class cruiser HMCS Ontario and Crown Colony-class cruiser HMCS Quebec) and have them, both near the end of their lives, get rebuilt as the guinea pigs of Canadian nuclear propulsion. Originally planned to only get a rebuild sufficient to use nuclear reactors, the RCN felt that if they were going to spend huge money rebuilding a cruiser to test nuclear propulsion, they should get more than a gun cruiser out of it. Thus, the rebuild of the two cruisers becomes more like the Albany-class cruisers of the USN. The front two pairs of guns were replaced with pairs of British twin 6" Mark N5 guns, while the back pair of 6" turrets were removed. The mid-section of the vessel became a nuclear power station in miniature, with two 135 MWt CANDU reactors and two steam generators were installed in the place of the boilers, though this required extensive rebuilding in the middle of the vessel.
The CANDU's lack of a heavy pressure vessel massively reduced the weight of the reactor and the refueling machines allowed regular refueling of the reactor as necessary. The vessel was designed with ports to allow new fuel to be loaded into the vessel without extensive overhauls, and the new reactors increased the power of the vessels to 100,000 horsepower, increasing the top speed of the two ships to just over 35 knots. The British 6" main guns were backed up by Vickers 3"/70-caliber secondaries in twin turrets (identical to those used on the Restigouche and Annapolis-class destroyer escorts of the RCN), and the vessel was also armed with American RIM-24 Tartar anti-aircraft missiles in twin Mark 11 launchers, similar to the system used on the Americans' incoming Albany-class cruisers. A large hangar and rear deck extension to operate Sea King helicopters, ASROC anti-submarine rocket launchers and side-mounted triple torpedo tubes completed the armament of the vessel. The ship's radars were also mostly American, with SPS-43 and SPS-30 air-search radars and SPG-51 fire control for the missiles, though the guns used British fire control systems. A large superstructure (mostly made of aluminum to save weight) was built, and the vessel's extra hotel power allowed for better creature comforts than some RN vessels.
The most expensive shipbuilding projects ever undertaken by the RCN, they were saved (along with the CF-105 Arrow fighter project [1]) from cutting by the Diefenbaker government by intense pushing by the RCN. Completed in 1961, the two vessels were commissioned into the RCN in 1962, beginning their service lives with testing of their propulsion capabilities. These tests turned out to be more successful than even the RCN had hoped for.
Quebec showed off the abilities of nuclear propulsion by, in a highly-publicized stunt, challenged the ocean liner SS United States to a race across the Atlantic. United States Lines accepted the challenge, and SS
United States and HMCS
Quebec raced from off of New York Harbor to Bishop Rock on the Isles of Sicily off Cornwall in the United Kingdom. while the warship was not eligible for the Blue Riband (by not being a commercial vessel), the Canadian warship won the race by just over two hours, averaging 35.1 knots across the Ocean. That performance was matched a year later when sister ship
Ontario joined the American Task Force 1 for Operation Sea Orbit, the non-refueled cruise around the world.
Ontario accomplished this with little difficulty, getting considerable press both in Canada and around the world. Better still, the two Canadian nuclear cruisers proved to be exceptionally reliable in service, both of them being the flagships of the RCN at the time and being popular ships, and with lower-than-expected operating costs, though it was figured by many that the traditionally-conservative leadership at both the RCN and AECL over-estimated the cost of operating the vessels.
Such was the suddenly-increased profile of the RCN during this time that the country's military spending actually grew substantially in the 1960s, helped by Canadair producing most of Canada's military aircraft and Canada's shipbuilding industries making their own weapons. At the same time, the RCN began to develop the Tribal-class destroyers. A huge debate went on with these vessels rather to power them with CANDU reactors or gas turbines, in the end a test ship, HMCS Haida, was built to test the gas turbine propulsion, while AECL developed a version of the CANDU reactor used by the cruisers that used higher-enriched uranium which improved power to 60,000 ship horsepower each, giving the same capabilities as the Iroquois-class through with the advantages (and costs) of nuclear power. In the end, the RCN chose to go with the nuclear propulsion, accepting the higher up-front cost and refueling costs for the advantage of higher speeds and greater flexibility. The four Tribals, however, became larger, more expensive vessels as a result, which made sure that the debate over the costs of nuclear-powered vessels was real. Regular NTU upgrades to Ontario and Quebec made sure that the debate was on as well.
What changed matters was Canada's decision to purchase the decommissioning British carrier HMS Eagle in 1972. That promise, made by Prime Minister Pierre Trudeau in 1972 in an attempt to use the Canadian Forces for political benefit and help the problems for the shipbuilding industries of Atlantic Canada, in a way settled the debates. The Eagle was purchased for little more than scrap value owing to her condition, but the vast shipyard at Saint John Shipbuilding in New Brunswick had an ambitious plan to turn the Eagle into a nuclear-powered vessel. This was in large part feasible due to the badly-worn condition of the Eagle's machinery. The now HMCS Eagle was completely rebuilt, and rusted hull midsections were cut open to pull out to replace the machinery. Four examples of the CANDU reactors used by the Tribals were installed, while the hull was lengthened in the tail and completely rehabilitated, while the angled deck was rebuilt and equipped with three steam catapults, while a single island was installed which was smaller in deck space but more roomy than the previous one. Room once used for fuel tanks was used for fresh-water production systems, extra aviation fuel and stores facilities and hotel improvements, while the elevators were rebuilt to be stronger to handle heavier aircraft. Equipped with F-4K Spey Phantom II fighters and Blackburn Buccaneer S.3 and LTV A-7E Corsair II attack aircraft, the latter modified slightly to use the powerful Allison TF41 turbofan, an improvement on the Rolls-Royce Speys used by the F-4K. The two classes was the result of wheeling and dealing by both the USN and RN - the RN wanted interoperability with the Canadian carrier and to prove the Bucc to the Americans, and the Corsair II had been delivered in part because the Americans, who were fighting in Canada's new fighter program at the time, had given the light bombers to the Canadians as an enticement for nothing.
Commissioned into the Navy by Queen Elizabeth II and then-Prime Minister Robert Stanfield in Halifax on June 22, 1976, the HMCS Eagle was the first Commonwealth CVN and it was clear almost immediately that the Canadian Navy's nuclear carrier, despite having cost over $1 Billion to build, was worth the money it had cost. Escorting HMY Brittania to Boston, New York and then Philadelphia in 1976 was the first duty for the mighty Canuck carrier, but in 1978 it began its most ambitious job, and indeed perhaps the most ambitious job ever undertaken by the Canadian Navy - a sailing around the world. Eagle, escorted by Quebec, Huron and Athabaskan, began Operation Northern Light on May 17, 1978, departing Esquimault. Unlike Operation Sea Orbit, Northern Light also included worldwide sailings of the other vessels of the Canadian Navy. Boiler-fueled Canadian ships, them escorted by refueling tankers, visited ports in Europe and Latin America, but
Eagle,
Quebec,
Huron and
Athabaskan left Vancouver, and after a visit to Seattle two days later headed across the Pacific. Pearl Harbor was visited first, followed by Yokohama, Kobe, Shanghai, Hong Kong, Subic Bay, Singapore, Jakarta, Sydney and Perth. A visit to Auckland was called off because of anti-nuclear concerns, but that was the only real flaw. Colombo, Mumbai, Karachi, Mombasa and Zanzibar followed, after that a long sailing right around Africa, next docking in Lagos and Abidjan. Meeting up with a number of other RCN vessels in Alexandria after Eagle and her escorts sailed through the Straits of Gibraltar, the fleet added Athens, Naples, Marseilles, Barcelona and Lisbon to its visits before finishing its visits to Rotterdam, Portsmouth, Dublin and Reykjavik before returning to Canada, docking in Halifax on September 4, 1978.
Such was the event's publicity that the RN was besieged with questions as to how the Canadians were topping them so massively, and the RN's embarrassment was made worse when a plan for Ark Royal to escort her sister across the Atlantic to Halifax was canned while Eagle was in Britain because of a mechanical failure. Anger over this was massive within the ranks of Britain's parliamentarians, but knowledge of Eagle's steep rebuilt cost made for difficulties accepting it. The Falklands War, however, ended that concern.
Ark Royal was unfit for service in that war, a decision that after the war was about as unacceptable as it could get. HMS
Ark Royal was reactivated for rebuild on July 27, 1982, and the RN began to plan a rebuild similar to the Canadians. Saint John Shipbuilding offered to do the job of rebuilding Ark Royal for the RN, but the British denied this, instead sending the ship to the British Shipbuilding shipyard in Barrow-in-Furness in northwestern England for a rebuild.
Ark Royal was built with new boilers and steam turbines, as nuclear propulsion was deemed too costly for the rebuild. But in the Spring of 1984, Britain announced that they would build three new carriers in the second half of the 1980s and into the 1990s, and explicitly invited Canada, Australia, India and France into the project. A month after the Ark Royal rebuild began, destroyer HMS
Bristol was called into drydock, with the goal of rebuilding it with a CANDU reactor system from the Tribal class for power. Canada supplied that to the RN, and
Bristol returned to the fleet in February 1984.
HMCS Haida was joined in the ranks of gas turbine-powered vessels in the Royal Canadian Navy by four modified air-defense vessels that had been ordered by the Iranian Navy but never delivered because of the Iranian revolution. Indeed, the Canadians played a role in the Iranian hostage crisis - they hid six American diplomats who had fled the embassy in Tehran as the students took over, and hid knowledge of it (with American approval) until Canada was able to acquire Iran's fleet of advanced F-14A Tomcat fighter aircraft. The exposures of the affairs infuriated the Iranians to such a degree that they attempted to cause terror attacks in Canada, but these attempts went nowhere and only resulted in arrests and more animosity between the nations. The Tomcats didn't end Canada's new fighter program, as the F-14s allowed Canada to eventually replace its fleet of aging CF-105 Arrows in the second half of the 1980s. Dealing with its expanding fleet forced Canada to acquire new supply ships for its fleet during this time, and to nobody's surprise by now, Canada had these ships, the Newfoundland-class vessels, built with nuclear power but with huge bunkers for marine diesel and jet fuel, the ships were designed to maintain 30 knot speeds to allow them to run with the carriers. The four new destroyers allowed Ontario and Quebec to go into the shipyards to extensive overhauls, which they did in 1983-84.
HMS
Ark Royal returned to the RN better than ever in September 1985, and was almost immediately a revelation to the British. Fast enough and capable enough to ride shotgun on the Americans' mighty Nimitz-class carriers even without nuclear propulsion, the Ark Royal was instrumental in making sure that the British wanted carrier aviation back for real. Even more stunning was the
Bristol. Aging steam turbines and Bristol-Siddeley Olympus gas turbines had been replaced by an ultramodern nuclear reactor, which made the ship go from an anachronism to one of the prides of the RN. Making things wilder still was Canada's nuclear submarine project. Canada preferred the Trafalgar-class submarine design, but the United States refused to grant permission for its export on non-proliferation terms. That annoyed the Canadians rather a lot, but AECL yet again rode to the rescue, proposing a Trafalgar with a twenty-foot hull stretch and a CANDU reactor for power, thus crossing out the Americans' concerns. Ottawa approved this in 1986, and the first vessel of the class was delivered to Canada by Cammell Laird in the UK in November 1988. The first two of seven submarines, HMCS
Victoria and HMCS
Chicoutimi, were built in the UK, but the other five were made by Canada Shipbuilding Corporation's new yards in Levis, Quebec. (Years later, it would emerge that the USN had wanted Canada to buy examples of the Los Angeles-class vessels, and that had been their objection to the sale of the Trafalgar.)
Cruisers
Ontario and
Quebec returned to the fleet in 1985-86, but age was starting to catch up to them, and after the fall of the Soviet Union the pioneering nuclear cruisers were decommissioned in 1993. The completion of the submarine program and the fighter purchases of the 1980s led to the Navy's next project - the Halifax-class patrol frigates. Such had been the results of the British Columbia-class destroyers that yet again the turbines vs. reactors debate was back on again, with turbine backers pointing out that Canada's development of its Newfoundland class vessels made range concerns much less relevant and the cost of the nucs was a major issue as the Iron Curtain fell. Nuclear backers pointed out that nuclear propulsion gave unlimited range and additional electric power upgrade abilities in the future, an important factor with the rapid advancement of computer technology in the 1980s. In the end, the Canadian Navy went with both.
Six examples of the patrol frigates, the Halifax-class (
Halifax,
Ville de Quebec,
Edmonton,
Winnipeg,
Toronto and
Ottawa), were built with longer hulls and greater armament, with two Mark 41 Vertical Launch Systems for anti-submarine rockets and anti-aircraft and cruise missiles and nuclear propulsion. Fourteen examples of the turbine-powered Vancouver-class frigates (
Vancouver,
Calgary,
Montreal,
Saskatoon,
Kingston,
Fredericton,
Charlottetown,
St. John's,
Sydney,
Brandon,
Kamloops,
Windsor,
Sherbrooke and
Lethbridge) were built for patrol duties and lighter duties closer to home and had just one Mark 41 system, as well as gas turbines for power. Both were, however, armed to the teeth in other areas - Mark 48 missile launchers for Sea Sparrow missiles, anti-submarine torpedo tubes, two 155mm guns (in a single forward mount) and two 76mm guns (in two mounts on either side of the bridge) and the ubiquitous anti-submarine helicopters. The Canadian frigates were all armed with Tomahawk cruise missiles and SM-2 Standard anti-aircraft weapons. The Patrol frigates saw the fleet's steam-powered vessels retired in the 1990s, and HMCS
Haida also was retired in 1995. The four Tribal-class nuclear destroyers went for updates in the 1990s as well.
Britain's nuclear carrier program's progress was slow, in large part due to the cost improving the British armed forces in the 1980s, but by the end of the Cold War there was a demand. India's aging carriers needed replacement, and with both
Ark Royal and
Eagle getting long in the tooth in their hulls (though the equipment in both cases was much newer) and Australia considering returning to carrier aviation, the demand was there. France's Charles de Gaulle aircraft carrier project had been delayed to the point where its hull had not been laid down in 1992, when they agreed to join the British in their carrier project. Canada agreed to involvement the following year, and Australia joined in 1995, after the government of newly-elected Prime Minister John Howard made it a priority, knowing of the problems and uncertainties in Indonesia to the north. India, after long negotiations with Russia about carrier replacement programs, backed out in 1996, claiming the cost of the carrier was too high. (They'd regret that.)
The plans were impressive. Australia was the only holdout against nuclear propulsion, but they eventually agreed to this as well. The ships would all use the latest evolution of the CANDU reactor design, this one being both smaller and more powerful than existing designs, each unit being somewhat bigger than American reactors but passively safe, able to be refueled on the move (even at 80% power) and able to operate on multiple fuels, a bonus for the Europeans (who had eyes on using MOX fuel) and India (which was working heavily with Thorium). The carrier used extensive automation to reduce crew sizes and thus operating costs, electromagnetic catapults, a larger flight deck and separate weapons and aircraft elevators to improve the rate to improve the rate of sorties. Computerized engineering spaces made sure that the number of men needed there was reduced, and the movement of the flight deck forward allowed for there to be more room on the back of the carrier for rearming. Canada insisted on (and got) the usage of the SMART-L search radar, a good move considering its huge range, and the design, finalized in 2004, envisioned a very high-tech vessel, admittedly one that was expected to be very expensive. Nevertheless, the four countries involved all placed their orders as the design was being finished up in the summer of 2003 - Britain would order three units (HMS
Queen Elizabeth II, HMS
Prince of Wales and HMS
Duke of Edinburgh), Canada would order two (HMCS
Victorious and HMCS
Magnificent), France two (FS
Charles de Gaulle and FS
Jean Bart) and Australia one (HMAS
Australia). Only
Australia would not be built in its home country, as Australia lacked a shipyard big enough for the job, and Canberra eventually ordered it from Versatile Pacific Shipbuilders in Vancouver, British Columbia, though its construction was supervised by Royal Australian Navy officers from the start, something Canada had no objections to. The carrier had been designed to use differing aircraft from the start, as the French wished to use their own Dassault Rafale and Super Etendard fighters. Australia elected to go all-American with their aircraft - F/A-18C/D Hornet and F/A-18E/F Super Hornets for the RAN's carrier. Canada and Britain, however, both elected to use the naval version of the Eurofighter Typhoon, while Canada also would use the F-14E Super Tomcat and the F/A-18 Hornet. Everyone across the board used E-2C Hawkeye AEW aircraft.
TBC....
