Russia's Failed Alfa Reactor: Rickover Rules, OK!

My friend from Texas has drawn my attention to the NATO name Alfa aka Alpha class "interceptor" SSN. It had the Russian, aka Soviet, name Project 705 "Lira". 

Russia's Alfa concept badly mixed up submarines with jetfighters. In 1957 the Russians begun planning this very small, small crew, highly automated, very fast, but very noisy submarine with either a highly innovative (but troublesome) OK-550 or BM-40A LCFR reactor. 

It was noise and the unconventional lead-bismuth cooled fast reactor  (LCFR) reactor that prematurely closed down the project after only 7 Alfas. They were only commissioned from 1971 to 1981.

LCFR technology greatly reduced the size of the Alfa's reactor compared to conventional pressurised water reactor (PWR) (water as coolant) dimensions. The Alfa's reactor permitted very high acceleration and overall speed (around 41 knots). This permitted Alfas to travel  from the Russian Northern Fleet Base, up into the Arctic Ocean, then down into the North Atlantic to attack NATO subs or ships. 

However, the LCFR reactor had a short lifetime and had to be kept warm (at Russia's very cold bases) when it was not being used.  

The LCFR was much more maintenance intensive than older, mature technology PWRs. The issue was that the lead/bismuth eutectic solution solidifies at 125 °C. If it ever hardened, it would be impossible to restart the reactor, since the fuel assemblies would be frozen in the solidified coolant. Thus, whenever the reactor is shut down, the liquid coolant must be heated externally from a pier-side source producing super-heated steam.

While the LCFR reactor worked for many years without stopping, they were not specifically designed for such treatment and any serious reactor maintenance became impossible. This led to a number of failures, including coolant leaks and one reactor broken down and frozen while at sea.
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A US LMFR FOR SUBMARINE?

In contrast the US Navy tried but quickly discarded a similar liquid metal "fast" LMFR plant. Part of the reason was Admiral Rickover's preference for standardized, mature, PWR technology. The first US SSN named USS Seawolf (SSN-575) is the only US submarine to have a sodium-cooled nuclear power plant. The reactor was known as S2G.  Seawolf-575 was commissioned in 1957, but it had leaks in its superheaters, which were bypassed. In order to standardize the reactors in the USN submarine fleet the submarine's sodium-cooled reactor was removed starting in 1958 and replaced with a PWR.
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Jive Turkey aka Sub Brief has produced a long Youtube description here and above of the Alfa Project.

POST ALFA SUBMARINE TRAITS THE RUSSIANS PRIORITIZED

41 minutes, 13 seconds into the Youtube Jive describes the reasons why the Russians  stopped making the Alfas. I summarise those reasons as:

- Russians realised stealthy-quieter subs preferable to noisy ones. Hence the follow-on
  Akula SSNs were/are stealthier than Alfas.
- Keeping LCFR plants critical-warm too expensive manpower, cost and time.
- Refueling LCFR dangerous, difficult and expensive.
- Liquid metal coolant Oxidized requiring replacement.
- Labour saving automated systems unreliable, failed at sea, couldn't be fixed there, and
- Automatic sonar less effective than a dedicated sonar team.

So large nuclear submarines powered by PWRs, with large crews (for at sea maintenance, safety and damage control) have become standard in All nuclear submarine navies.