In the 2017 defence policy, Strong, Secure Engaged,[1] Canada reaffirmed its commitment to maintaining a submarine capability as part of a balanced Blue Water Navy; a navy that is capable of responding across the complete spectrum of maritime operations over a vast maritime estate. The understanding that submarines remain a key element of balanced naval forces is important and can be seen in their dramatic growth in their numbers worldwide, as more countries opt to acquire or expand upon a submarine  capability.[2] However, it is their unique role in protection of national security interests that is the determining factor – this was powerfully articulated in a recent speech outlining Australia’s Defence Strategic Update – a nation with remarkably similar challenges and requirements.[3]

All submarine operating nations acquire submarines that meet their specific requirements, which are usually defined by geography and fiscal resources. Not surprisingly, in order to maintain a presence in Canada’s three oceans, Canadian naval forces must be designed for operations that routinely face the most extreme of ocean conditions. Acknowledging the Pacific and Atlantic coasts are a demanding environment; the challenge is of course the Arctic, as it is covered in ice and prolonged operations under the ice require a submarine to be able to operate far from support facilities without having to surface. To date, this capability been the sole domain of the nuclear-powered submarine, as it demands air independent power generation and the amount of power that has heretofore only been capable of being generated by a nuclear reactor.[4]  

A Modern Submarine

Modern ocean-going submarines, be they nuclear or conventionally powered, are remarkably similar – what differs between the two is how they generate power. The front section of the submarine is where command and control is exercised from, equipment is operated, and the crew accommodated – a common feature that includes the same weapons and sensors suite regardless of the fitted power generation system, which typically occupies the stern section of the submarine. All that said, it is worthwhile to clarify some key points about submarines, particularly as they apply to under-ice operations.

  • A conventionally powered (diesel electric) submarine generates power by running diesel generators and stores this power in large storage batteries.  These batteries then supply power for everything the submarine uses: the propulsion motor(s), weapons and sensors, all domestic needs, etc. A simple and well proven system that has been in use for over a century, however, these batteries have a finite capacity to store electrical energy that, depending on usage, demands the submarine recharge them regularly. Recharging the battery is accomplished by coming to periscope depth and raising a snorkel or ‘snort’ mast above the surface and running the air-breathing diesel generators. The submerged endurance of these submarines is therefore dictated by the state of the battery charge. This is most notable in the biggest draw on electrical power, which is propulsion, where slow speed can offer days of operation, but high speeds can literally see a battery depleted in minutes.
  • Conventional submarines fitted with an Air-Independent Power (AIP) system to augment their diesel generators, have enhanced submerged endurance that is subject to the capabilities and limitations of the fitted AIP system.[5] These AIP systems generate power (kilowatts) and allow the battery to be partially charged whilst remaining submerged, without having to snort. It is important to note that while these systems can dramatically increase the endurance of a low-speed patrolling submarine, their requirement for additional specific fuels significantly limits how long they can operate, as well as, impacting sustainment activities when forward deployed. Therefore, AIP systems are typically not used for long distance submerged transits to and from an operational patrol area.
  • Nuclear powered submarines produce power by having a nuclear reactor generate heat that is used to create steam in a Pressurised Water Reactor (PWR) system.[6]  The steam is then used to power turbines or turbo-alternators to propel the submarine, as well as, generate electricity (megawatts). Because a nuclear reactor is a true air-independent power generation system, there is no requirement for the submarine to snort nor carry additional fuel types. Moreover, because the core life of a modern naval nuclear reactor is designed to last the service life of the submarine, submerged endurance is dictated by the amount of food it can carry for its crew.
  • Ice – a submarine can surface through ice but there are some very finite limitations. Typically, when conducting under-ice operations, most submarines surface in what is called a polynya, which is an area of open water or very thin ice that shifts with the overall ice-pack movement. While the exact thickness of ice that a submarine can surface through is dependent of the design of the submarine itself, and specific details are understandably classified, it is almost certainly less than three metres and often less than one metre. Submarines pictured surfacing through the ice are fitted with specialized equipment and have searched for an appropriate area to surface, which can often take some time as the ice field is continually shifting. To be clear, a submarine cannot surface whenever and wherever it chooses when conducting under ice operations.[7]
  • Atmosphere – once a submarine dives it is necessary to monitor the atmosphere and change it as required. In a nuclear submarine, a liveable atmosphere is manufactured through a very power intensive process of electrolysis of seawater to produce oxygen combined with the use of carbon dioxide scrubbers. Because the reactor generates sufficient power, this process does not require the submarine to snort. In the case of conventional (including AIP fitted) submarines, the atmosphere is completely changed out when snorting, and although there are abilities to prolong breathable atmosphere whilst dived, they are necessarily limited. Moreover, should there be a major fire while operating under the ice, all submarines must return to the surface and snort to clear smoke. It is this factor, which precludes non-nuclear-powered submarines from conducting deep under-ice operations, as the time it takes to be able to clear the ice edge, or find a polynya, to either surface or snort is limited by the extant capacity of the battery and the fitted Emergency Breathing System (EBS).

Nuclear Power

Given the above, one would ask why does Canada not simply invest in a fleet of nuclear-powered submarines? As a nation with a domestic nuclear power generation industry there is no technical reason why Canada could not build and maintain nuclear-powered submarines. In fact, Canada has investigated acquiring nuclear submarines twice before, and in both cases the Government decided not to proceed because it was unaffordable, as it would have impacted other Canadian government initiatives. 

The cost of a nuclear-powered submarine fleet is driven by a multitude of factors, notably it is the magnitude of the supporting nuclear infrastructure, not the submarine itself, which determines the overall project costs. During the Canadian Submarine Acquisition Project – SSN in the late 1980s it was the substantial cost of the infrastructure, on both coasts, that was the determining factor in the decision not to proceed.[8] Often when costs of nuclear submarines are publicly cited, they reflect the unit cost to build a particular type of submarine, but they do not address the total costs of naval nuclear power. There were some other factors that influenced the decision process – let me explain:

  • Infrastructure – regulations authorizing the operation of nuclear power plants are understandably quite demanding, and all associated infrastructure must meet exceedingly high standards of construction to allow for extremely unlikely scenarios (e.g. a massive earthquake at the moment of withdrawing a reactor core). This is coupled with heightened security arrangements, as well as, extensive education and training programmes for all those involved with nuclear propulsion – the latter must be routinely re-certified to meet regulatory standards. As no western navy has had a major nuclear accident since the inception of naval nuclear power in 1955, the stringent certification process has absolutely no latitude for negligence.[9]
  • Intellectual Property (IP) – if Canada were to acquire nuclear-powered submarines it would not independently design a new naval nuclear reactor, rather it would licence this technology from an allied nation. The authorization for the release of this technology would not be something Canada could control nor could it own the IP – it would be up to the host nation to dictate terms and conditions. While Canada operates civilian nuclear power stations using a CANDU reactor, it is important to understand that the PWR in use in submarines is completely different to the Canadian CANDU reactors and is not interchangeable. In short, while Canada has resident expertise in civilian nuclear power, it does not have the domestic expertise to design, build and operate naval nuclear reactors, which would be prohibitively expensive to develop.[10]

The Dilemma

Understanding that it is very unlikely that Canada will invest in nuclear-powered submarines the question remains as to how will Canadian submarines patrol in all three oceans that border Canada? Much has been written of late of the evolution of non-nuclear submarine AIP, however, the fact remains that no AIP system in service today can meet the power requirements for long transits and prolonged operations beyond the ice edge. So, one may ask who will develop such a system?

Nations that operate nuclear submarines have invested considerable sums on nuclear infrastructure and are unlikely to be interested in funding development of an alternate power source. Conversely those nations that have developed non-nuclear AIP are nations that routinely operate their submarines close to home with easy access to supporting infrastructure and their national supply chain. By not having to go far from home and not having to operate under ice, the current AIP systems are adequate to meet the patrol requirements of these smaller submarines – but they are not reflective of the demands of Canadian geography.[11] Simply put, Canada requires a larger submarine than currently is in service with most navies, except those with nuclear-powered submarines. With the possible exception of Australia and the Netherlands, Canada would have to invest in the development of this technology on its own, which could prove to be cost prohibitive.[12]

A Potential Solution

In contemplating Canada’s dilemma, it is clear the ideal solution is unlikely to be forthcoming without significant investment by either government or industry. However, there are a number of areas that can significantly enhance submarine operations – these being power generation and storage plus unmanned underwater vehicles (UUVs). All of these technologies have evolved considerably of late, but are not without their detractions and, as such, require further development. Specifically:

  • Power generation – of the AIP systems currently in use today, the fuel cell is the quietest system and offers the most promise for future development by commercial industry. Like other AIP systems it requires liquid oxygen stored in tanks, as well as, hydrogen stored separately to “transform chemical energy directly to electrical energy”.[13] That said, the French Naval Group has recently trialed a new FC2G AIP System, which eliminates the need to store hydrogen, as it uses a reformer to produce hydrogen from diesel fuel to combine with liquid oxygen to generate electricity. Regardless of type of system used, AIP endurance remains limited by the amount of liquid oxygen the submarine can carry, which at this time would preclude it from long submerged transits.[14]
  • Power storage – In an attempt to maximize the output of fitted power generation devices, increased battery storage, while not a panacea, can offer some significant improvement to legacy lead acid batteries. A number of evolving battery systems, most notably Lithium Ion batteries (LIB), have significant drawbacks because they are not designed for submarine operations – in the case of LIB it is thermal runaway and the subsequent risk of a catastrophic fire that remains unresolved. As the main battery storage is a critical factor in the design of the submarine, continued incremental improvement in submarine battery technology, such as nickel-zinc batteries, will see progress – but will it ever be enough to power an ocean-going submarine for sustained submerged operations?[15]

So, if a non-nuclear-powered Canadian submarine is restricted to ice-edge operations, does that mean it cannot patrol Canada’s Arctic waters? Conventional thinking would have one believe this, however, the evolution of unmanned underwater vehicles (UUVs) has been quietly developing over a number of decades and Canada has been a leader in its development from the onset. A patrolling submarine could launch and/or control a UUV from the ice edge and while this is proven technology, the challenges become:

  • What is the optimal physical size of the vehicle?
  • How to communicate with the vehicle and share the data? and
  • How to recover the vehicle?

Modern UUVs can perform a multitude of missions which include rapid hydrographic survey, Mine Countermeasures (MCM) – including Route Survey,[16] Anti-Submarine Warfare (ASW), oceanography, Intelligence, Surveillance and Reconnaissance (ISR), amongst others. Leveraging extant technology, UUVs can covertly and effectively help assert Canadian sovereignty in the Arctic and greatly expand the reach of a patrolling submarine – today.

The size of UUVs vary greatly from small man-portable variants to Heavy Weight Vehicles (HWV) – designed to fit inside a standard 533 mm torpedo tube, such as General Dynamics Bluefin [17] –  to large UUVs designed for long endurance and large payloads such as International Submarine Engineering’s Theseus UUV.[18]  In fact, Canada has set UUV under-ice records, with a vehicle spending 12 days under the ice, surveying close to 1,000 km, before being recovered.[19] So yes, UUVs are part of the future of undersea warfare and can be part of an under-ice patrol solution, however, they are not a panacea and loss or interruption of the mission must be expected. Moreover, there are some inherent factors that limit unrestricted UUV use in under ice operations. Specifically:

  • Launch and recovery – while HWV can be launched from a standard torpedo tube (as the HMVs are the same size as in-service torpedoes), recovery is problematic. An option is for a submarine to covertly launch the UUV and have it recovered later by a surface support ship, such as a DeWolf-class Arctic Offshore Patrol Vessel. Otherwise, the UUV could egress to a safe point and the submarine then recovers it from the surface. Alternatively, bigger submarines can piggy-back large UUVs, however this can place limitations on the manoeuvrability of the parent submarine and may entail stability issues in most conventional submarine designs.
  • Mission control – once the UUV is deployed on a specific pre-defined mission it can collect and transmit information back to the controlling unit either acoustically (low data rate) or by satellite link by coming to the surface in a polynya. The latter allows for re-tasking the UUV whilst deployed but is subject to prevailing ice conditions. 
  • Endurance/Communications – these two limiting factors of the UUV could be mitigated by pre-deployed submerged docking stations which would extend the UUV endurance by charging the UUV battery, as well as, acting as a communications relay station via a buoy or shore station for large data dumps to supported units.[20]

In addition to submarine launched and controlled UUVs, larger unmanned submarines are being developed to act as a “mother ship” for smaller UUVs. Known as Extra Large Unmanned Undersea Vehicles (XLUUV), such as Lockheed Martin’s ORCA, these are being developed to compliment submarine operations by allowing for greater undersea operational awareness, endurance measured in months and the ability to support various operations with different re-configurable payloads.[21]

In conclusion, the optimal submarine propulsion solution for the covert transit of large distances and protracted under ice operations remains with nuclear power for the foreseeable future. However, if Canada wishes to maximize the effectiveness of current and future non-nuclear powered submarines, then the answer will be a combination of evolving power generation and storage technology while maximizing existing UUV capabilities. In short, if Canada wants to go beyond ice-edge operations and conduct prolonged operations under the ice, it must either go nuclear or unmanned.

[1] accessed 18 June 2020.

[2] accessed 6 July 2020.

[3]  “Submarines are fundamentally important to our defence strategy. They are a unique – and powerful deterrent to any adversary, and they are critical to protecting our national security interests. Submarines secure Australia’s strategic advantage – through leading-edge surveillance and the protection of our maritime approaches”. 6 July 2020.

[4] accessed 11 June 2020.  

[5]  “AIP is often described as Air-Independent Propulsion, however the term has become outdated. As well as propelling the submarine, AIP provides electrical power for ship systems including domestic needs, hence the term Air Independent Power.  See accessed 11 June 2020.

[6] Almost all naval nuclear reactors are Pressurized Water Reactors (PWR) using water as a coolant, however, there were some Soviet and one US submarine fitted with liquid metal cooled reactors which were problematic to operate and discontinued – see: 11 June 2020.

[7] accessed 11 June 2020.

[8] Gimblett, Richard H., ed. (2009). The Naval Service of Canada 1910–2010: The Centennial Story. Toronto: Dundurn Press, pgs 179-181 and accessed 11 June 2020.

[9] The US Navy’s formidable nuclear safety record demanded an equal investment by Canada and was a major reason why the US was initially not supportive of Canada’s SSN programme. See: accessed 11 June 2020.

[10] A CANDU reactor is a very large reactor which uses un-enriched uranium as a fuel with heavy water as a moderator whereas a submarine PWR is a very small reactor which uses enriched uranium as a fuel and ordinary water under pressure as a moderator see: accessed 11 June 2020.

[11] For example, the transit distance from Halifax NS to Churchill MB is the same distance as a trans-Atlantic crossing from Halifax NS to the UK, which at an average transit speed of 8 knots would take 15 days. Note, AIP systems are designed for slower speeds (typically 5 knots) for covert patrolling.,%20Canada&d=Port%20of%20Plymouth,%20United%20Kingdom Accessed 8 July 2020

[12] Routine ice edge operations would demand a bigger hull, that is strengthened, to surface through ice in an emergency, as well as enhanced navigation and life support systems.  Moreover, operating in the Arctic requires total self-sufficiency as shore-based support is not available and the submarine must be large enough to carry sufficient fuel and stores, as well as being able to meet environmental regulations which preclude any discharge (e.g. large holding tanks).

[13] accessed 11 June 2020.

[14] accessed 6 July 2020.

[15] accessed 6 July 2020.

[16] “Route Survey is a Mine Counter Measure (MCM) technique that uses side scan sonars to determine optimal shipping route selection (in terms of ease of mine detection) through the pre-survey of all objects along these routes, and in times of conflict, the re-survey of these routes to find differences”. See: accessed 11 June 2020.

[17] accessed 11 June 2020.

[18] accessed 11 June 2020.

[19] accessed 11 June 2020.

[20] accessed 11 June 2020.

[21] accessed 8 July 2020.