ABSTRACT
At 01.23 hours on 26 April 1986, Unit No. 4 of the Chernobyl Nuclear Power Station was operating at low power prior to a scheduled shutdown when a sudden, very rapid and uncontrolled power increase occurred. This resulted in the destruction of the reactor core and severe damage to the reactor building. There was a release of radioactive material from the core over the subsequent 9 days. The accident is now known to have occurred as a result of a test which was being carried out by the operators. The manner in which the test was conducted, including the disabling of all the safety systems provided to protect the plant, was the immediate cause of the accident. However, aspects of the reactor design resulted in the adverse response of the reactor which caused its destruction.
