BN-600 reactor

BN-600 reactor. It is a sodium-cooled fast reactor and the third unit of the Beloyarsk Nuclear Power Station located near Zarechny, Sverdlovsk Oblast in Russia. As a cornerstone of the Soviet and later Russian fast-neutron reactor program, it represents a significant technological step between the earlier BN-350 and the subsequent BN-800 reactor. The reactor has provided valuable operational experience for the development of closed nuclear fuel cycle technologies and advanced reactor designs.

Design and specifications

The BN-600 is a pool-type reactor where the primary sodium coolant circuit and the core are contained within a large vessel. Its design thermal power is 1470 MW, generating 600 MW of electrical output for the grid operated by Rosenergoatom. The reactor core uses a mixed oxide fuel (MOX) blend of plutonium and uranium oxides, reflecting its role in breeding fissile material. Key components include the intermediate heat exchanger and steam generator systems that transfer heat from the radioactive primary sodium loop to a secondary non-radioactive sodium loop, and then to water to produce steam for the turbine. The primary vessel is constructed from stainless steel to withstand the high operating temperatures and corrosive nature of liquid sodium.

Operational history

Construction began in 1969, with the reactor achieving first criticality in 1980 and entering commercial operation later that year. Operated by the staff at Beloyarsk Nuclear Power Station, it has established one of the world's longest and most successful track records for a fast reactor. Throughout its service, the BN-600 has experienced several sodium leaks in its auxiliary circuits, but its design prevented any serious radiological consequences. In 2014, it was joined at the site by the more advanced BN-800 reactor, creating a unique two-fast-reactor complex. Its operational longevity has provided an immense dataset for the International Atomic Energy Agency and influenced projects like the MBIR research reactor.

Safety features and systems

Safety is achieved through multiple passive and active systems inherent to the sodium-cooled design. The large thermal inertia of the sodium pool and the natural circulation capability of the coolant provide passive decay heat removal. The reactor is equipped with diverse and redundant shutdown systems, including control rods and backup absorber elements. Containment structures are designed to manage potential sodium fires, with specialized fire suppression systems using argon and powder agents. The separation of the radioactive primary sodium from the water/steam system by the intermediate loop is a fundamental safety barrier, preventing energetic chemical reactions.

Fuel cycle and nuclear materials

The reactor operates as part of a strategy to develop a closed nuclear fuel cycle, reducing waste and utilizing recycled materials. Its core initially used enriched uranium but transitioned to MOX fuel, incorporating plutonium from reprocessed VVER reactor spent fuel. This process demonstrates the breeding potential of fast reactors, creating more fissile plutonium-239 from uranium-238 than is consumed. Spent fuel from the BN-600 is sent for reprocessing at facilities like Mayak, with the aim of recycling actinides. This experience directly supports fuel development for the BN-800 reactor and future designs like the BN-1200.

Role in nuclear energy development

The BN-600 has been a critical testbed for fast reactor technology within the Russian nuclear program, managed historically by the Kurchatov Institute and OKBM Afrikantov. Its operational success validated key design principles for sodium-cooled reactors, influencing international projects such as Joyo in Japan and the Prototype Fast Breeder Reactor in India. The reactor's performance has provided essential data for the Generation IV International Forum, particularly for the Sodium-cooled fast reactor (SFR) system. It remains a pivotal link in the technological chain from the BN-350 reactor to future commercial fast reactors aimed at sustainable nuclear energy.

Category:Nuclear power stations in Russia Category:Fast-neutron reactors Category:Soviet inventions