RBMK Reactors (RBMK)

RBMK reactors are existing only in countries of the former USSR. The RBMK is a boiling water reactor, with pressure tubes containing the fuel elements. The moderator is graphite. The core consists of a graphite stack with drill holes for the pressure tubes. The coolant flows through the channels from bottom to the top of the core. The reactor cooling system consists of 2 loops. The steam- water mixture leaving the core is led to 2 separators, from where the steam is led to the turbines.

Control rods are inserted into the core from above. Integrity of the confinement system (hermozone) depends on suppression pools like in BWRs.


  1. refueling machine
  2. gas-tight steel vessel
  3. concrete confinement
  4. steam/water separator
  5. steam pipe
  6. refueling tube
  7. reactore core: consists of a cylindrical stack of graphite (height 7 m, diameter 12m), with channels. The coolant flows through the channels which contain the pressure tubes with the fuel.
  8. main coolant pump
  9. cooling water from separator