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Project 645 ZhMT

In 1952 work on development of heavy liquid metal reactor plants with lead-bismuth coolant for nuclear submarines began at OKB “GIDROPRESS”. The first reactor plant which ensured a successful solution of the task on development of a nuclear steam supply system (NSSS) for nuclear submarines was a 27/VT rig constructed in Obninsk at the industrial site of the Institute of Physics and Power Engineering in 1958. The NSSS documentation was developed by specialists of OKB “GIDROPRESS” and the NSSS equipment was manufactured by Podolsk Machine Building Plant named after Ordzhonikidze.

The 27/VT rig was a ground-based submarine prototype of design 627/VT which is a full-scale half of the nuclear submarine board including reactor, steam generator, pumps, primary and secondary pipelines, turbine plant, control system and other service systems. The 27/VT rig was constructed for complete engineering development of each equipment and system of NSSS, refinement of reactor plant operational conditions and control as well as for submarine crew training. For the first time in the world a liquid metal reactor plant of 17500 HP power was installed in a small area and provided with high secondary steam parameters (pressure 42 kg/cm2, temperature 440°C) and primary pressure about 20 kg/cm2.

One Project 645 ZhMT submarine was built. Commissioned on 30 October 1963, K-27 was a modified November-class SSN equipped with two VT-1 type liquid metal (lead-bismuth) cooled reactors. The steel hull was divided into seven compartments: 1 Torpedo room; 2 Accumulators and Living accommodation; 3 Control room; 4 Reactor compartment; 5 Turbo and diesel generators, cooling and auxiliary machinery; 6 Turbines; 7 Generator. It was modified to test the reactors that were intended for use on the high-speed Alfa-class submarines. During sea trials on 24 May 1968, a sudden and unexplained loss of reactor power occurred. Radioactive gases began to leak into the reactor compartment, and nine members of the crew died from radiation sickness. K-27 was never returned to service.

On October 22, 1955 came the party and the government decree on the establishment of an experimental nuclear attack submarine project 645 with a two-reactor steam supply system with a hyperbolic liquid metal-coolant (lead-bismuth alloy). Originally the development was under the leadership of VN Peregudova, and in 1956 he was replaced by AK Nazarov. Chief of the Navy were watching AN Donchenko and A.Gubkin.

Once the tactical and technical requirements for a new boat had been issued, the work started immediately with the technical design stage: it was assumed that the submarine project 645 was to be different from the boat of Project 627 only with respect to the power plant, which would evaluate as objectively as possible propulsion with liquid metal coolant.

However, to fully implement this plan failed. In the ship design changes were made due the first nuclear-powered ships operating experience and the results of tests of an experimental nuclear power plant with liquid metal at the Physics and Power Engineering. Maintenance work on the project was finished in autumn 1956, though it should be noted that it did not put stringent requirements on the noise of the boat and the influence of its acoustic noises on the airborne sonar. As part of the design calculations were performed only critical speed propeller noise in the compartments of the ship.

In November 1957 working drawings were issued, and on June 15, 1958 the nuclear-powered prototype evalution was held in Severodvinsk. His afloat on April 1, 1962 and October 30, 1963 the Project 645 tactical number "K-27" was included in the Navy. As ships of Project 627, the new submarine was intended to combat surface ships and transport vessels of the enemy during operations in oceanic and remote maritime theaters.

In 1964 and 1965 nuclear submarine K-27 performed two autonomous voyages of 51 and 52 days without emersion which were the records for the Soviet Navy submarines.

In May 1968, K-27 went to sea to test the functionality of the power plant, as well as to practice combat training missions. May 24 when checking the parameters of the power plant at full stroke has been a sharp drop in reactor power. At the same time has been a significant increase in the pressure in the gas system of the primary circuit, increasing the coolant level in the buffer tank and the appearance of water in the emergency condenser.

The most probable cause of the accident, which killed nine members of the nuclear submarine crew, was a sharp deterioration in the core heat removal from penetrating into the oxides of lead-bismuth alloy and slag. In connection with the accident, additional research on the effects of alloy and dissolved oxides on the circulation of coolant was required, as well as the state of the circuit surfaces, studying the conditions of formation of insoluble residues and dust oxides. The results were used in the development of reactors for boats 705 Lira project.

After the accident recovery of "K-27" was considered inappropriate. For 13 years he was in reserve, and then transferred to the the breakers.

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