RBMK Type Reactor
The Kursk Nuclear Power Plant is a nuclear power plant located in western Russia on the bank of the Seym River. The four reactors at the plant are RBMK-1000 reactors.
The RBMK type reactor (reaktor bolshoy moshchnosti kanalnyy) was developed and exclusively used in the countries of the former Soviet Union. It was based on a reactor used to produce weapons grade plutonium. In 2010, there were 12 operating RBMK reactors and none are under construction.
Natural or slightly enriched uranium (to 1.8%) inserted in fuel rods 7 meters long is used as the fuel. Each rod resides in a fuel channel. In the reactor core, there are 1,693 channels. The reactor core diameter is 11.8 meters and it is 7 meters high. The reactor is not encased in a steel or concrete envelope. These reactors may be refueled under power.
Graphite bricks stacked around the fuel channels are used as the moderator. Ordinary water flowing upwards through the channels is used as the coolant. The water boils directly inside the channels. Its pressure when exiting the core is 6.9 MPa and temperature 280 °C. The steam is dried and supplied directly to a turbine. This is a single-circuit power plant.
The most famous RBMK type reactor is reactor number 4 of the Ukrainian Chernobyl nuclear power plant that in 1986 experienced, due to operator error, the worst nuclear power plant accident in the history of the nuclear power industry.