Thirty Years after the Chernobyl Accident: The View on the Origin and Development

The value of the positive scram effect on the control rods is discussed, which, in the authors’ opinion, was the trigger for the accident. The results of the calculation by a new STEPAN reactor code version, which uses the surface harmonics method for description of the neutron transport, are presented. The magnitude of the neutron burst during the accident is estimated and its relation to high graphite temperatures of more than 1000°C observed after the destruction of the reactor is established. The influence of the neutron burst on the radiation characteristics and the decay heat of the fuel during the first hours after the destruction of the reactor is considered.