RBMK

The RBMK, or Reaktor Bolshoy Moshchnosti Kanalny (High Power Channel-type Reactor), is a type of graphite-moderated nuclear reactor that was developed in the Soviet Union. It is a pressure tube reactor design, meaning that the fuel is contained in individual tubes that pass through a graphite moderator. This design allows for on-power refueling, meaning that fuel can be replaced while the reactor is still operating, a feature that was considered a significant advantage.

RBMK reactors are characterized by their large size and high power output. They use enriched uranium as fuel and light water as coolant. The graphite moderator allows for a positive void coefficient, a characteristic that has been a subject of significant safety concern. This means that if the coolant boils and turns to steam (voids), the nuclear reaction can increase rather than decrease, potentially leading to a power surge.

The most well-known incident involving an RBMK reactor was the Chernobyl disaster in 1986. This event highlighted some of the inherent safety issues associated with the RBMK design, particularly the positive void coefficient and other design flaws that contributed to the accident. Following Chernobyl, significant modifications were made to the remaining operating RBMK reactors to improve their safety. Despite these upgrades, the RBMK design is no longer being built, and remaining reactors are gradually being phased out.