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OK-650 Atomic Reactor, Submarine

Immediately after the completion of the development of second-generation nuclear power plants for the USSR submarine fleet, the development of a nuclear submarine for advanced nuclear submarines, considered as third-generation ships, was organized. Based on the studies of the head institute of the Navy, the main requirements for new installations were put forward, from which the designers proceeded when creating the appearance of the installations and the execution of the main equipment.

The design and construction of the third generation nuclear submarines required the creation of such ship nuclear atomic power plants (AEU), which in their quality indicators would significantly surpass the second generation ship nuclear power plants. In particular, to create third-generation plants, the task was to increase their power by more than 2 times compared with the previous ones, but without significant changes in weight and dimensions. At the same time, it was necessary to ensure higher safety, reliability, maintainability, acoustic secrecy, and maneuverability compared to second-generation plants. This task was complicated by the fact that it was planned to create one unified steam generating installation (PPU) for various classes of the third generation nuclear submarines.

To solve all these problems, the development of PPU was carried out on a competitive basis. The competition was attended by OKBM, NIKIET, Central Research Institute named after ac. A.N. Krylova, as well as the design bureau of the Izhora plant.

As a result of consideration of the projects completed by 1965, the scientific and technical council of the 1st Central Research Institute of the Ministry of Defense with the participation of all interested enterprises, and then the STM MSM, recommended the OK-650B installation proposed by the Special Design Bureau of Mechanical Engineering (OKBM) for further development. Thus, the dream of I.I. Afrikantov on the development of all equipment for transport PPU in OKBM A large team of highly qualified employees led by F.M. Mitenkova.

The third generation reactor installation was fundamentally different in layout. This was due to the fact that the designers were faced with the task of reducing the installation time of the installation at a shipyard, which was achieved through an enlarged assembly of components and assemblies at engineering plants.

The problem of ensuring high compactness of the installation was solved by significantly increasing the energy intensity of the core. In addition, the energy intensity of the steam generator was increased, and the aggregation of the main equipment was also provided. Thanks to the indicated technical solutions, it was possible to create a unit, the steam generating unit of which could be transported by rail. This made it possible to produce the entire unit, including the reactor vessel, steam generators, pumps and primary circuit cleaning filters, at a machine-building plant and thereby improve the quality of manufacturing of critical PPU elements.

To increase reliability and safety, the OK-650B installation was performed with a sufficiently high level of natural circulation of the primary coolant. This was achieved by placing steam generators above the core, as well as a significant reduction in the hydraulic resistance of the primary circuit, for which the OKBM developed a steam generator with the movement of the primary coolant in the annulus. Ensuring the natural circulation of the primary coolant allowed not only cooling with the use of a batteryless cooling system, but also operating under running conditions without primary pumps at capacities up to about 30% of the nominal. The latter made it possible to reduce the number of primary pumps to two, which to some extent offset the increase in the dimensions of the nuclear reactor installation, caused by the need for natural circulation.

At OK-650, the reactor control and protection system has changed significantly. The introduction of pulsed equipment made it possible to control its state at any power level, including in a subcritical state. The mechanism of "self-propelled" was installed on the compensating organs, which, when the power supply disappeared, ensured the lowering of the gratings to the lower limit switches. In this case, complete “jamming” of the reactor occurred even when the ship capsized.

From the very beginning it was decided that the first sample of a nuclear installation must be tested at a full-scale ground test bench. In 1965, the terms of reference for the construction of the KV-1 stand, which was assigned the OK-650BK index, were approved in the newly created State Testing Station (IAE branch, NITI, Sosnovy Bor).

In parallel with the construction of the KV-1 stand, on the instructions of the nuclear submarine designers, the designers developed modifications of the OK-650 project with their binding to specific ships. For the nuclear submarine of project 945 Barracuda (design bureau Lazurit), the OKP-650A polypropylene with one reactor installation was intended. For the nuclear submarine of project 971 “Shchuka-B” (design bureau “Malakhit”), the OKP-650B polypropylene with one reactor was intended. For the nuclear submarine of project 685 “Fin” (design bureau “Rubin”), the OKP-650B-3 PPU with one reactor installation was intended. For the nuclear submarine of project 941 “Shark” (design bureau “Rubin”), the OKP-650VV PPU with two reactor units was intended. PPU-650B with two reactor units was intended for the nuclear submarine of Project 949 Granit (design bureau Rubin), and OK-650V with two reactor units was intended for the nuclear submarines of Project 949A Antey. Modified OKU-650 type technical design standardized for all third-generation nuclear submarine projects for propeller power up to 50 thousand hp was approved in 1967. The thermal power of the OK-650 PPU was 190 MW.

Uranium enrichment of 21-45% was used as fuel. In the third generation of nuclear power plants, core profiling was used with nuclear fuel and a burnable absorber. Cross-shaped fuel rods were created for the OK-650 PUF, which had a number of advantages. The cross-shaped design provided the maximum heating area. In addition, the swirling profile of the fuel element allows you to turbulize the flow of coolant, and also use the principle of self-spacing.

In contrast to the reactors of previous generations, a number of equipment was included in the OKBM technical design, the design and manufacture of which were previously carried out by the shipbuilding industry, for example, iron protection tanks (ZHVZ). In this regard, OKBM specialists had to master previously unused grades of ship steel, welding and control methods. So, three ZhVZ tanks were made of high-strength steel with a thickness of 16-100 mm and were distinguished by an abundance of welded joints. The lower tank, which is a large-sized welded structure filled with lead blocks and water, was the foundation of the entire unit, and was installed using special support plates on the foundation of the main hull of the vessel.

Production of the PPU block for the KV-1 stand was completed in February 1974, and after its control assembly, the block was delivered to Sosnovy Bor. The installation of the ground prototype PPU OK-650 stand was completed at the end of 1975. Over the next year, the HF stand passed the acceptance tests in full, and subsequently the life tests of the power plant with an imitation of an autonomous trip.

During the tests, not only the main characteristics of the installation were confirmed, but also the possibility of increasing power during operation on natural circulation, as well as the heating rate of the primary coolant when the unit was put into operation, was revealed.

As a result, for the first time in domestic practice, more than two years before the installation of a nuclear power plant (NPP) at the first new generation nuclear submarine, important information was received at the stand on the installation of the NPP and the operation of its equipment and systems, and the identified shortcomings were eliminated, for example, leakage of some compounds . Thanks to this, the tests and delivery of the head and then serial third-generation nuclear submarines with OK-650 PPU passed practically without delay.

Subsequent operation of the KV-1 test bench revealed certain shortcomings and omissions regarding the active zones, the pressure compensation system and the cleaning system, which were subsequently eliminated, and the installation as a whole was modernized in the direction of simplifying the manufacturing technology and increasing the steam generator energy intensity.

For all modifications of the PUF, the following deadlines were set for the launch of the main nuclear submarine of each project: project 949 - December 1980, project 941 - November 1981, project 685 - December 1983, project 945 - September 1984 and project 971 - December 1984 .

The main purpose of the new nuclear submarines of Project 949 ("Granite") was the destruction of enemy carrier-based strike formations. The lead boat of project 949 Arkhangelsk (K-525) was laid down at the Sevmash enterprise on July 25, 1975, launched on May 3, 1980, and entered service on January 24, 1981.

The main purpose of the new Project 941 nuclear submarines (Shark) was to launch intercontinental ballistic missiles with nuclear warheads at targets on enemy territory. The lead boat of project 941 Dmitry Donskoy (TK-208, “heavy cruiser”) was laid down at the Sevmash enterprise in June 1976, launched on September 29, 1980 and entered service on December 12, 1981.

The main purpose of the new Project 685 nuclear submarines (Fin) was the search, detection, long-term tracking and destruction of nuclear submarines, the fight against aircraft carrier formations, large surface ships and enemy transports. Project 685 nuclear submarines were positioned as the deepest. The lead boat of project 685 Komsomolets (K-278) was laid at Sevmash enterprise on April 22, 1978. The construction of the ship was carried out using the block method, each finished block passed comprehensive tests in special docking chambers. Launching took place on June 3, 1983 and came into operation on December 28, 1983.

The main purpose of the new nuclear submarines of Project 945 (Barracuda) was tracking missile submarines and aircraft carrier strike groups of a potential enemy, as well as guaranteed destruction of these targets with the outbreak of hostilities. The nuclear submarine of the 945th project is designed to combat not only enemy missile submarines, but also surface ships from aircraft carrier formations and attack groups. The lead boat of Project 945 “Crab” (K-276) was laid in Sormovo on July 20, 1979, launched on July 29, 1983, and entered service on September 21, 1984. The main purpose of the new multipurpose nuclear submarines of Project 971 (Shchuka-B) was the fight against enemy naval groups and submarines, as well as special operations, mine operations and reconnaissance. The lead boat of Project 971 “Shark” (K-284) was laid down in Komsomolsk-on-Amur in 1980, launched on October 6, 1982 and entered service on December 30, 1984.

In 1987, the first nuclear-powered submarines with OK-650 PPU revealed several cases of premature depressurization of fuel rods in active zones and the formation of cracks in welds at damping units. The causes of these phenomena were quickly established and, thanks to urgent measures taken, were eliminated.

The experience of operating ships with third-generation nuclear power plants showed that compliance with the principles of self-protection of reactor facilities and the multiplicity of protective barriers in them mainly prevented the release of radioactive substances outside the reactor compartment and thereby limit the consequences of nuclear power plant and / or ship accidents for personnel, the population and the environment Wednesday. The implementation of these principles was ensured by careful design and guarantees of workmanship, sophistication, reliability and survivability of ship systems and equipment, effective functioning of the systems for diagnosing and monitoring their condition, and a high level of training and qualification of personnel.