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The BOREY Class Russian SSBN: You Get What You Pay For

By Bruce Rule - Jul 10, 2017

As previously discussed, BOREY Class Russian SSBNs should not be described as a “fourth-generation” nuclear submarines. They are – at best – modified third-generation hulls that employ 30+ year-old propulsion and hull components from scrapped AKULA and OSCAR hulls with a Rube Goldberg approach to noise reduction: the use of a turbo-electric (TE) capability for slow-speeds.

The objective of the TE capability is to reduce the acoustic vulnerabilities of the GTZA (Geared Turbine Assembly) OK-9VM produced by the two-stage epicyclic design reduction gear that is difficult to effectively quiet because the design requires the use of gear-tooth combinations that insure the repeated contact (wear) of the same teeth on meshing gears, and because of gear-float due to inferior gear-cutting technology then available.

As also previously discussed, the main propulsion turbine and integral gear system cannot be shut-down during TE mode operations because - if needed for high-speed operations - the GTZA must be brought on-line slowly to avoid uneven heating and shape distortion of turbine blades; hence, it must be kept basically idling during TE mode operations which means that turbine blade-rates, and gear system mesh-rate and hobbing error components are still exploitable.

The following (unclassified) discusses how the US delt with a related issue with S5W reactor systems: (quote) Place the Main Propulsion Turbines “on the jack” to allow even heating during startup. “On-the-Jack” is a term for a small electric motor that keeps the main turbines and the propulsion Bull Gear slowly rotating during engineering plant startup. (end quote)