Review: A Brief Technical History of PLAN Nuclear Submarines

Original Article

My Outline

Submarines are an important component of any navy. They possess the ability to pass undetected, gathering information and carrying out attacks, forcing adversaries to commit disproportionate numbers of ships and aircraft to tracking and neutralizing them. This makes them a key component of sea denial strategies. Even a small force of submarines can make it vastly more complex for an adversary navy to transport troops, launch attacks or impose a blockade.

Nuclear submarines amplify these advantages. With powerplants capable of generating virtually limitless amounts of energy, nuclear submarines can circle the globe without having to come up for air. This level of endurance significantly expands tactical options, allowing the submarine to exert its influence even in regions far away from its home nation's coastline.

For a ballistic missile submarine, the advantages of nuclear power are even more pronounced. Nuclear propulsion allows ballistic missile submarines to patrol without surfacing, giving nations an ability to launch or respond to nuclear attack with systems that are virtually undetectable until they choose to fire their missiles. Ballistic missile submarines are an essential part of the "nuclear triad", providing the assured retaliation against any pre-emptive nuclear attack.

For China, specifically, the utility of submarines is even more obvious. The primary obstacle to increasing Chinese influence around Taiwan and the South China Sea is the presence of the United States Navy. Submarines, and, more specifically, nuclear submarines, could represent a key threat to the US Navy's aircraft carriers. A nuclear submarine is one of the few systems that can pose a threat to a carrier no matter where it is. Possessing advanced nuclear submarines, therefore, could be a key advantage for the People's Liberation Army Navy, as it seeks to counter the US Navy in a potential Taiwan or South China Sea conflict scenario.

However, as Christopher P. Carlson and Howard Wang show in their report, "A Brief Technical History of PLAN Nuclear Submarines", published by the China Maritime Studies Institute, China's efforts at building nuclear submarines have been anything but smooth or consistent. Chinese nuclear submarine construction efforts have been affected by political upheaval and shifting priorities, and, as a result, current Chinese nuclear submarine technology is significantly inferior to that of the United States.

China's efforts at building nuclear submarines begin in the late '50s. In 1958, Mao Zedong authorized the "09 Project", an effort by the Chinese military to construct an indigenous nuclear submarine. At this time, the US had demonstrated its lead in nuclear submarines with the Nautilus, while the Soviet Union was rushing to catch up with its November-class. The Chinese military, correctly comprehending the revolutionary advantages of nuclear power for submarine propulsion, sought to develop its own nuclear submarines.

The Chinese government initially sought assistance from the Soviet Union for nuclear reactor and submarine design. This assistance was not forthcoming, due to the Sino-Soviet split caused by Nikita Khrushchev's de-Stalinization campaign, leading to Chinese leaders choosing a path of indigenous self-reliance, as initial design work began in 1959. Work on the nuclear submarine project proceeded slowly for the next four years, hampered by China's lack of nuclear expertise and the economic and political upheavals caused by the Great Leap Forward. In 1963, the Chinese government put the submarine project on hold in order to reassign nuclear scientists to China's atomic bomb project. After China's successful test of an atomic bomb in 1964, the project to build a nuclear submarine finally began in earnest in 1965, fully seven years after the initial commencement of the project.

China's goal with the submarine project was to build a nuclear powered ballistic missile submarine, allowing the PLA to maintain its own nuclear triad, just like its main rivals, the United States and Soviet Union. However, the Chinese government understood that developing a new ballistic missile simultaneously with a submarine capable of launching it underwater was too ambitious a goal. Therefore they decided to break the problem into parts. The first submarine, the Type 091, would be a nuclear-powered attack submarine. While the Type 091 was being designed and built, work would proceed on a ballistic missile capable of being launched from a submerged platform. Then, once the missile was ready, a new submarine, the Type 092, would be built to accept the missile and give China its long desired assured second-strike capability.

Although the Type 091 was intended to advance Chinese shipbuilding technology in preparation for the Type 092 ballistic missile submarine, it was intended to be a capable combat platform in its own right. The PLAN had ambitious requirements for the Type 091, specifying a 300m maximum dive depth, the same as the existing Romeo-class diesel-electric submarines, despite having a pressure hull nearly twice the diameter. Furthermore, the 091 was required to be able to launch torpedoes at that maximum depth, unlike the Romeo-class submarines which could not launch torpedoes at depths greater than 80m.

The greatest challenge that Chinese designers had with the Type 091 was the nuclear reactor. Cut off from both Western and Soviet reactor design expertise, they had to design a naval reactor from scratch, using only what details they could glean from open-source data on US, Soviet and other nations' efforts to use nuclear reactors for civilian merchant vessels. To this end, the Chinese looked at the Otto Hahn, the Savannah, and the Mutsu, nuclear-powered merchant ships designed by West Germany, the United States and Japan, respectively as well as the Soviet nuclear-powered icebreaker, Lenin. In 1965, they chose a loop-type pressurized water reactor, similar to that found on the Savannah and Lenin and the final design work began on the Type 091, with Chinese engineers taking a calculated risk to design the reactor and the hull in parallel.

In 1967, the final technical drawings were completed, and the first Type 091, hull number 401, was launched from Bohai Shipyard in Huludao on December 26, 1970, Mao Zedong's 77th birthday. The submarine concluded its sea trials and was commissioned into the PLAN in 1974. A second hull was commissioned in 1980, after a long delay caused by the Cultural Revolution. Another three hulls followed relatively quickly thereafter, with hulls 403, 404 and 405 being commissioned in '84, '88, and '91, respectively.

While the Type 091 was undoubtedly a triumph for the PLAN, making it just the fourth nation to gain the ability to build a nuclear-powered submarine, it was also beset with problems, especially with the first two hulls, 401 and 402. These had significant corrosion issues and reactor leaks, causing radioactive coolant to pool in engineering spaces, sickening the crew. While the radiation leaks were addressed by lengthening the hull for 403, 404, and 405, reliability remained an ongoing concern with this type, with a test dive to the maximum rated depth of 300m only occurring in 1988.

Offensive capabilities were also limited. The reactor was loud and underpowered, capable of driving the submarine only to a maximum speed of 24 or 25 knots. Noise levels were comparable to the Soviet Hotel, Echo and November class submarines from the 1960s. The requirement to launch torpedoes at maximum depth meant that new torpedoes had to be developed. These torpedoes were not available until 1989, meaning that for the first 15 years of the Type 091's existence they had no offensive weapon, leading to them being nicknamed "toothless sharks".

The Type 092 ballistic missile submarine, despite being derived from the Type 091, was also beset by challenges. Design work began in 1971, but the chaos of the Cultural Revolution meant that the only instance of the submarine, hull 406, was not actually launched until a decade later. The development of the JL-1 ballistic missile for the submarine proceeded slowly with numerous failures, with a successful test launch only occurring in 1988. Despite process improvements to reactor construction yielding a 20% increase in power over the early Type 091 hulls, the increase in drag from the missile compartment meant the Type 092 was significantly slower, with a maximum speed of only 22 knots. Reliability continued to be an issue here as well, with the Type 092 spending more time tied to a pier than out on patrol, leading Western observers to characterize it as more of an R&D platform than an operational weapons system.

At this point, Chinese submarine-building efforts entered a long pause. Mao Zedong had passed away, and his successor, Deng Xiaoping, was not convinced of the utility of nuclear submarines. Although Deng did allow the Type 091s and Type 092 production runs to finish, no new nuclear submarine construction work would take place in China until 1994, when Deng was succeeded by Jiang Zemin, and work started on the Type 093 and 094.

English language data on the Type 093, and its ballistic missile counterpart, the Type 094, are sparse. However, some details can be gleaned from open-source data published by the Chinese government and the US Navy. The Type 093 was designed as a successor to the Type 091, and it was intended to be a nuclear submarine that would be viable against US submarines and surface ships. US analysts suggested that the design goal was to match the Soviet Victor-III class in terms of underwater speed and radiated noise levels. Design work for these submarines commenced in 1994, and the first two examples of the Type 093, hulls 407 and 408, were launched in 2002 and 2003, respectively.

After these two submarines were commissioned, in 2006 and 2007, it became clear that the design goals had not been met. Although these submarines are thought to possess a dual reactor design capable of higher power output than the single reactors of the Type 091, maximum top speeds fell short of the design goal of 30 knots, with Western analysts placing the top speed of the Type 093 in the 26-28 knot range. Noise levels, too, were below target, with the US office of Naval Intelligence publishing an assessment in 2009 indicating that the Type 093's radiated noise levels were roughly comparable with the Victor-I class, barely better than that of the Type 091. This indicated that Chinese noise isolation technology was considerably behind even late-Soviet technology, and that Chinese submarines did not have the raft-like substructures that Soviet and American submarines use to insulate vibrating machinery from the pressure-hull.

Following the initial pair of hulls, Type 093 production entered a hiatus, as Chinese submarine shipyards focused on production of the Type 094 ballistic missile submarine. During this time, the Chinese government purchased a significant amount of Russian naval technology, including more advanced noise isolation mounts like those used on the Akula and Yasen-class submarines. These, along with better anechoic coatings, further streamlining, and machinery to operate a towed-array sonar were incorporated into a revision of the Type 093, the Type 093A. Launched at a rate of one per year from 2015 to 2018, the Type 093A managed to meet the original design goal of 30 kts underwater speed. Although the Type 093As still lack raft structures as their pressure hull is too narrow, the incorporation of more advanced Russian noise isolation mounts has led to a reduction in radiated noise, allowing the Type 093A to meet its other goal of having radiated noise levels comparable with the Soviet Victor-III class.

Currently, Chinese shipyards appear to be building a further iteration of the Type 093, the Type 093B. Thought to be launching sometime in the mid-2020s, the Type 093B will have a lengthened hull and a pump-jet propulsor instead of a traditional screw. While the performance of the Type 093B is still unknown, analysts believe its acoustic signature could be as low as that of the Soviet Sierra-class.

Just as the Type 092 ballistic missile submarine was a derivative of the Type 091, China's current Type 094 ballistic missile submarines are a derivative of the Type 093. The Type 094's missile section is much larger and more ungainly than that of the Type 092, due to the larger JL-2 missiles it carries. As a result, despite having significantly more reactor power, the Type 094 only capable of a maximum speed of 24 knots, barely faster than the 22 knot maximum speed of the Type 092. The JL-2 missile's range of 7,200 km is far higher than the 2,500 km maximum range of the JL-1, but it is still insufficient to allow Chinese submarines to hit targets in the contiguous United States from their bastions near the Chinese coastline. They will only gain this capability when they are outfitted with the forthcoming JL-3 missile, which is thought to have a range of greater than 10,000 km.

Even as construction is proceeding on the Type 093B, Chinese designers are working on a newer, third generation of submarine, launching in the 2030s. While it's impossible to know the specific details of this new design, some priorities can be ascertained by looking at existing trends in Chinese submarine design, OSINT photos of pressure hull sections, and broader trends in submarine construction. It's very likely that the future Type 095 and 096 will move back to a single-reactor design, thanks to advanced reactor technology that China acquired from Russia through a 2010 nuclear technology partnership. It's also likely that the pressure hull of the 095/096 will be larger than that of the 093/094, allowing for the installation of a raft substructure for noise isolation. The use of pump-jet propulsors instead of screws is also likely, further reducing noise levels. As a result, Carlson and Wang think that the Type 095/096 could be similar in terms of noise and performance to the Soviet Akula-class.

In terms of armament, the addition of VLS cells to China's Type 032 submarine technology testbed indicates that the Type 095 may be a SSGN, with VLS cells capable of launching land attack or anti-ship cruise missiles. While these missiles can currently be launched from torpedo tubes, a VLS would significantly increase the salvo size. However, the number of VLS that each Type 095 will accommodate will likely be less than the number carried by an Ohio-class SSGN, given that the diameter of the pressure hull will be smaller and Chinese VLS tubes are larger than their American counterparts.

Unlike Carlson and Wang, I do not think that Chinese submarines are on the verge of matching or outperforming their American, British or (soon to be) Australian counterparts. The history of Chinese submarine construction has been one of shifting priorities, delays and underperformance. The currently deployed state of the art Chinese submarines are roughly comparable to the Soviet Victor-III, a forty-plus year old design, which even at the time of its debut was inferior to its American and British counterparts. The next generation of submarines, not scheduled to be deployed until the 2030s are, optimistically, thought to match Soviet submarine technology from the end of the Cold War. Given past results, it would be surprising Chinese shipbuilders manage to hit those targets, and even if they do, it's not clear that they would present a significantly greater threat to US carriers than the Soviet submarines they trained to defeat during the Cold War. The production rate of Chinese shipyards have been similarly unimpressive, with them completing one hull per year at their fastest, comparable to the production rate of Virginia-class submarines by the United States.

While China has demonstrated impressive progress with its submarine technology, after starting from scratch in 1958, Chinese submarine development has been slow, affected by both the political and social upheaval of the Great Leap Forward and the Cultural Revolution, and shifting priorities during the leadership of Deng Xiaoping and Jiang Zemin. As a result, Chinese submarines retain significant disadvantages compared to their American counterparts, and future submarines should be expected to close this gap only marginally. Chinese nuclear submarines do represent a threat to American naval power in the Western Pacific and South China Sea, but the threat is a manageable one, which can be dealt with through increased investments in anti-submarine warfare training and technology.