Chernobyl, Pripyat, The Ukraine
Number & type of Reactors
4x RBMK 1000
Net Electric Power as % in 92 of national total
1850 MWe, 5% of nat. total
Major population Centers in a 150 km radius and
total estimated population of 150 km r. region
Approximately 3.5 million, including Kiev and parts of Belorus; 654,000 in the "voluntary resettlement zone"
Date of commercial operation start up
or (if unfinished) date of construction start.
Startup dates 1978, 79, 82 and 84
RBMK reactors have a number of serious safety problems, notably the fact that the formation of steam bubbles in the tubes of the reactor actually causes the rate of the reaction to increase, causing the formation of still more steam bubbles, causing the reaction to go out of control.
In addition, RBMK plants have a slow-acting scram system which has graphite "followers" attach to the control rods, causing a substantial increase in reactivity when the control rods are inserted from the fully withdrawn position. Finally, the reactor is especially unstable at low power. While attempts have been made to address these problems, units 1 and 3 at Chernobyl are operating in especially difficult conditions due to the high levels of radiation in the area from the Unit 4 disaster, especially in the case of unit 3, which shares the same building as block 4.