excess reactivity

excess reactivity

[′ek‚ses ‚rē·ak′tiv·əd·ē]
(nucleonics)
The amount of surplus reactivity over that needed to achieve criticality; it is built into a reactor (by using extra fuel) in order to compensate for fuel burnup and the accumulation of fission-product poisons during operation.
References in periodicals archive ?
The drive provides triggering, Power control, Compensating for excess reactivity, And stopping the reactor by triggering the active zone or pulling out the hrk cartridge.