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The Sensitivity of Positive Scram Reactivity to Neutronic Decoupling in the RBMK-1000

1989; Taylor & Francis; Volume: 103; Issue: 3 Linguagem: Inglês

10.13182/nse89-a23680

1943-748X

P. S. W. Chan, A.R. Dastur,

Graphite, nuclear technology, radiation studies

The sensitivity to the axial neutron flux distribution of the positive reactivity that may have been introduced on initiation of scram in Chernobyl-4 has been evaluated. It is found that the scram reactivity is positive and its size is remarkably insensitive to a wide range of axial flux distortion provided the flux shape is concave, which is a characteristic of neutronic decoupling of the core. In contrast, the scram reactivity is negative when flux shapes are convex, i.e., those that are a characteristic of strong neutronic coupling. This indicates that unless there were a significant number of control absorbers present in the core just before the accident to provide a convex flux shape, the chances that some positive scram reactivity was inserted to initiate the power pulse are high.