>>I would love to know the Soviet experience with the Alfas-<<
It wasn't pretty.
That they only built six of them...and one was supposedly converted to a pressurized water reactor...says quite a lot in my book. They didn't serve for very long because of all the problems they had with these boats. The prototype was scrapped after a reactor accident, and another was only returned, briefly, to service after a five year long refit. They were also damned expensive to build and to keep up as well as of questionable utility. So much so that in the Soviet Navy, they were known sarcastically as "Golden Carps!"
The laundry list of problems with these boats is a long one, not the least of which was a crude automation system, a small crew (About 30 guys) and extreme difficulties in maintaining the reactor, all of which made for boats regarded as unsafe by the Soviets. You might want to get a copy of "The World's Worst Warships: The Failures and Repercussions of Naval Design and Construction, 1860-2000" by the late Antony Preston for a more involved discussion of this. Amazon is offering it at
http://www.amazon.com/gp/product/1557500045/qid=1140458362/sr=1-1/ref=sr_1_1/002-9463386-0872062?s=books&v=glance&n=283155
The idea of using a liquid metal cooled reactor in prnciple offered some attractive advantages, not the least of which was greater thermal efficency, but the problem with sodium is that it's corrosive as hell and reacts violently to contact with water. (In other words, it goes BOOM!) Not surprisingly, both the U.S. and Soviet navies abandoned sodium cooled reactors very quickly.
The problem with lead-bismuth used in the Lira class (The Soviet name for the Alfas) was that it had to be kept hot all the time or it would feeze solid. It also had to be regenrated frequently which was not a good set up for boats that would have to make long patrols.
