Thread by @Saturnax1

#SubMonday #Submarines #NavalNews #Technology #ColdWar
The sail of Project 661 Anchar/Papa-class nuclear-powered cruise missile submarine K-222, the fastest submarine ever built, to be preserved as a memorial in Primorsky Park in Severodvinsk.
Here's a short🧵on this unique project:

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Project 661 Anchar/Papa-class design works started in the late 50s in the naval design bureau Malachit (then TsKB-16).
Soviet Navy wasn't satisfied with the performance of their 1st generation of nuclear-powered cruise missile submarines (SSGN), e.g. the Project 659/Echo I or Project 675/Echo II-class boats, mainly due to the reason these were only able to launch their missiles while surfaced.
Soviet Navy urgently needed a new class of high-performance submarines, able to deliver a devastating strike while submerged.
The ambitious initial technical specification of the Project 661 included:
- high-speed titanium hull submarine
- twin liquid metal cooled nuclear reactor powerplant (LMR)
- ability to strike the enemy aircraft carrier groups with ten P-70 Ametist/SS-N-7 Starbright solid-fuel anti-ship missiles.

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The first drawings drafts were approved in 1960 and after the technical solution was approved in 1961 the first titanium hull sections were made at the SEVMASH Shipyard.
The use of titanium proved to be extremely challenging and special manufacturing procedures had to be implemented.
For example, the welding of titanium requires a cleanroom with an argon atmosphere to prevent the weld contamination. For this purpose SEVMASH built a special welding chamber. Upgraded version is called Atmosfera-2 and is still operational (photos 1-4 by SEVMASH).
Atmosfera-2 was build in 1971 with internal volume of 300m3 and this is where the titanium pipelines for nuclear-powered submarines are welded in a high-purity argon atmosphere.
Only specially trained & qualified welders are allowed to work in the chamber after passing several medical examinations. Paramedic personnel is always on watch nearby the chamber during all welding sessions.
Before entering, welders must put on a special protective suit with a clean air inlet & a waste air outlet. Welders are allowed to spend max. 4.5hrs in the chamber according to their work instructions.

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The initial technical specification called for use of twin liquid metal cooled nuclear reactors (LMR), however a simpler pressurized-water reactor (PWR) was ultimately selected.
Soviet Navy experimented with the LMR technology on Project 645/November-class SSN K-27 - the first Soviet submarine to use lead/bismuth liquid metal-cooled reactor (LMR).
This technology later deployed on the famous Project 705 Lira/Alfa-class fast interceptor SSNs.
While impressive on the paper, the LMR turned out to be a complicated and troublesome technical solution, resulting in many accidents with irreversible coolant solidifying and radiation accidents.
I covered the tragic story of K-27 (photos 1 & 2) here:

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The final approved design of Project 661 resulted in a double-hulled submarine displacing 7000t submerged, with a hull length of 107m, beam 11.5m and draft 8.2m.
Powered by a two V-5R PWR reactors using enriched uranium-235 fuel to produce 177 MW (237,000 hp) of power, two 40,000 hp steam turbines GTZA-618 coupled to two propeller shafts with 2 fixed pitch propellers.
The armament consisted of ten launch tubes for P-70 Ametist/SS-N-7 Starbright solid-fuel anti-ship missiles and four 533 mm (21 in) torpedo tubes in the bow with onboard store of 12 torpedoes.

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The hull of K-18 was laid down at SEVMASH on December 28, 1963 as a shipyard hull №501. While still under construction the hull was renamed to K-162 in 1965. Also in 1965, a high concertation of argon in the welding chamber led to a suffocation of welders preparing their workstation, leading to air-quality control equipment installation.
K-162 was launched on December 21, 1968. During the initial sea trials the boat reached underwater speed of 42 knots, leading to a some mechanical damage to the sail and several torn off hatches.
She was commissioned into the Northern Fleet on December 31, 1969.
On December 18, 1970 K-162 reached underwater speed of 44.7 knots (82.8 km/h, or 51.4 mph). In order to reach this speed, safety protection for the steam turbines was turned off and switched to manual operation mode.
On January 15, 1978 she was reclassified to K-222 and finally decommissioned in December 1984.
The hull of K-222 was scrapped in 2010 in Zvezdochka plant, Severodvinsk (photo 1), the spent nuclear fuel from her reactors was sent to Mayak nuclear facility plan for storage and processing, and sealed nuclear reactor compartment (photo 2) was sent to Sayda Guba nuclear reactor storage facility for a long-term storage (photos 3 & 4).

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An improved modification of the Project 661 called 661M was proposed in 1970, but at that time there were a much cheaper Project 670 Skat/Charlie I-class SSGN already being deployed, followed shortly by Project 670M Chayka/Charlie II-class boats, leading to a cancellation of all new design proposals for the Project 661.
Last Charlie II-class SSGNs were decommissioned mid 1990s and replaced by Project 949 Granit/Oscar I and Project 949A Antey/Oscar II-class, which are now gradually replaced by the latest Project 885 Yasen and Project 885M Yasen-M/Severodvinsk-class nuclear-powered cruise missile submarines.
Photo of K-162 pin badge commemorating her speed record of 44.7 knots while submerged.
End of 🧵

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