Fast breeder reactor of BN-600 type is the world-largest one in its reactor class operating safely during 25 years.
Nuclear fuel for BN-600 fast breeder is manufactured at OAO MSZ in the form of fuel assemblies and delivered to Unit 3 of Beloyarsk NPP (Russia). The reactor core is made up of three fuel assembly types containing fuel of various enrichments – 17%, 21 %, 26 % (in U-235). Fuel assemblies contained in the reactor core are designed for thermal energy generation and its transfer to the coolant flow.
A BN-600 FA consists of a top nozzle, central piece and bottom nozzle. The top nozzle is designed for coupling with refueling mechanisms during FA loading and unloading. There are flow holes on the top nozzle providing for the coolant circulation. The central piece is a hexagonal tube housing the fuel bundle of 127 rods. The bottom nozzle provides for the insertion and retention of FA in the reactor as well as for the specific coolant flow through the FA. The fuel rods are filled with UO2 pellets enriched in U-235. End-face breeding blankets of fuel rods are loaded with depleted uranium dioxide pellets. FA used in the blanket is designed for proper heat removal and generation of Pu. Dimensions and design of the blanket FA are similar to those of the core FA, the difference consists in the number (37 pcs.) and design of fuel rods. Fuel rods operating in the blanket are filled with depleted uranium dioxide pellets.
BN fuel rods are tubes made of special steels, filled with fuel and sealed by end-plugs though welding. Spacing between fuel rods and shroud tube is assured by means of winding the wire on fuel rods with a specific pitch. Fuel rods are manufactured in automated production line equipped with state-of-the art control and inspection facilities guaranteeing product safety and high quality. Application of low-swelling cladding and shroud materials, three various fuel enrichments as well as improvement of design and fuel rod manufacturing technologies has resulted in enhancement of FA characteristics and safe operation in BN-600 reactor. By means of continuous development of advanced fuel rod structural materials the manufacturer is able to increase fuel burn-up and FA performance indicators. At present, the FA burn-up makes 11,3 % of heavy atoms and is the best value world-wide. The transition to the 11,3 % burn-up has been completed; the work related to burn-up increase up to 15 % is in progress.
Key technical characteristics
Number of FA in the core, pcs.
Number of FA in the blanket, pcs.
Coolant pressure, MPa
Coolant temperature at core inlet, °C
Coolant temperature at core outlet, °C
Characteristics of the core FA
FA max. thermal power, MW
Service life, years
Number of fuel rods per FA, pcs.
Uranium weight per FA, kg:
Fuel enrichment (U-235 content in uranium)
In the core
17, 21, 26 %
In axial blankets (depleted uranium)
< 0,7 %
Overall FA width
Max. specific thermal energy production depending on the enrichment, MW day/ kgU: