Russian Navy Looking at Ways to Reduce the Crew Size of its Nuclear Submarines

: Posted On Sunday, 28 February 2016 10:49

Naval Forces News - Russia

Russian Navy Looking at Ways to Reduce the Crew Size of its Nuclear Submarines

Russian military leaders are pondering the feasibility of nuclear-powered submarines with their crews sharply reduced owing to onboard systems automation, a source in defense industry told TASS on Friday. Ships like that - Project 705 and 705K Lira-class (NATO reporting name: Alfa-class) torpedo submarines - used to be built in the Soviet Union. Their high performance were owing to the numerous original solutions they embodied. Their automated nuclear reactor and armament control systems both allowed a crew reduction and yielded a wealth of experience in shipborne electronics development.

Project 705K Alfa class SSNs had a reduced crew

The key novelty, which determined the future of the design, was the choice of the main propulsion plant. It was a small-size fast neutron reactor with a liquid-metal coolant. The ship's displacement diminished by about 300 tons owing to a higher temperature of the steam and, hence, a higher effectiveness of the turbine. The liquid-metal coolant was a lead-bismuth alloy boiling at 1,679°C.

However, the reactor had an inherent flaw due to its liquid-metal coolant. The lead-bismuth alloy crystallizes at 145°C, and the operating temperature in the primary coolant circuit of such reactors cannot be allowed to drop that low. For the liquid-metal coolant not to harden, a certain temperature of the reactor had to be maintained continuously, which had an impact on the operation of the submarines. In particular, using the basing infrastructure was difficult to them. In addition, the liquid-metal coolant had to be continuously monitored and regularly purified of oxides as well.

The submarines of the class carried an integrated automated control system that was a real breakthrough at the time - the unique Accord action information system that enabled the control room to exercise total control of the ship. The integrated automation allowed using weapons, gathering and processing tactical data, performing tactical maneuvers, displaying the situation, navigating and controlling the ship and its hardware automatically and remotely. The integrated automation of the Project 705 submarine allowed reducing its crew to 31 commissioned and warrant officers.

The advanced submarine had six 533-mm bow pneumatic/hydraulic torpedo tubes fit for use anywhere from the periscope depth to the diving limit. The Project 705 ship carried 18 SAET-60 or SAT-65 torpedoes.

The lead ship's official tests took place in December 1969. They provided for attaining full speed for 12 hours, full-speed maximum rudder deflection and the testing of all mechanisms and closure devices, including torpedo tubes, at full speed. The pitot and acoustic logs indicated a speed of 42 knots at 80% of the reactor's power and at 300 rpm of the shaft, with 20% of power being in reserve. A new underwater navigation phenomenon was discovered during the trials. The hydrodynamic noise caused by turbulent flows around the hull would start increasing at a speed in excess of 35 knots. Inside the submarine, it sounded like an aircraft generating 100 dB.

Project 945 Barracuda-class (Sierra I) titanium-hull submarine

The Lira-class submarines featured extremely high acceleration and maneuverability owing to their main propulsion plants. They were able to gain full speed in 1 min., with their acceleration rate similar to that of a plane. Their high speed enabled them quickly to get into a dead area of any surface ship or submarine, even if the enemy sonar had detected them. The submarines in the class could tail the potential enemy's boats for hours, preventing them from either breaking contact or attacking. The high speed and maneuverability of the Project 705 submarines allowed a full-speed 180-deg. turn in only 42 s. The Liras did not allow opposition to get into their rear dead areas that were especially useful for stealthy stalking and attacking with a torpedo.

However, the submarines of the class had considerable drawbacks as well, the principal one being high noise. Their mechanisms would malfunction, and their repair was very difficult due to the shortage of spares and hampered access to units and instruments. The small crew - a strong point of the design - made it impossible for the submarines to be maintained at sea. The Project 705/705K ships' integrated automation made no provision for controlling the systems in an emergency, and, since the electronic componentry had grown obsolete, its reliability deteriorated. The reactor peculiarities resulted in the submarines of the class being able to be serviced at three Soviet naval bases only.

The reliable maintaining of the liquid-metal coolant's temperature by means of on-shore equipment proved impossible, and the job was done by the heat radiated by the reactor itself. This led to its expedited service life expiry. The cramped compartments of the submarines offered poor habitability and accommodation for their complements who were dissatisfied with the low reliability of the ships as a whole.

However, is it possible today to develop a submarine similar to the Lira and does the Russian Navy need it? According to military expert opinion, there is no technical problems preventing the development of small-screw submarines now. Automation systems have evolved much since then, and 21st-century action information systems have to meet utterly different requirements. For instance, Yasen-class (Severodvinsk-class) multirole submarines are highly automated ships. Their Okrug action information system exercises real-time monitoring of their combat systems and information both on the ship's status and fed by the observation and target designation equipment.

However, the operation of sophisticated automated systems has certain standards for crewmen to meet. Ideally, the crews of such submarines could total 64 commissioned and warrant officers, but they actually account for 93. The more sophisticated the equipment, the higher skillful the use. Thus, fitting submarines with automated systems often increases their complements instead of reducing them.

Automating naval hardware to slash crews is the long-time trend in the world's major navies. First, it is due to the crew consuming a sizeable part of the budget. On the other hand, a small crew hampers survivability: a large crew can contain underwater damage or put out a fire and control the ship at the same time, while a small one cannot.

Finally, there are other issues with future robotized submarines. First, is Russia's defense industry capable of building a series of ships like that? Second, can the Defense Ministry afford such programs now that there is an economic recession?

For instance, the Severodvinsk-based Zvyozdochka Shipyard had to suspend the upgrade of two Project 945 Barracuda-class (Sierra I) titanium-hull submarines - the B-239 Carp and B-276 Kostroma in the winter of 2014/2015. The cause was a cut in the military spending due to the financial crisis and, as the military believed, an excessive cost of the program. It became known late in 2016 that the Navy had decided to have two Project 677 Lada-class (Petersburg) submarines completed and terminate the series at that. The funds will be reallocated to the advanced Kalina program with the first submarine to be built only after 2020. Therefore, the resurrecting the Lira may encounter considerable problems - financial ones in the first place, military experts presume.

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