METHOD AND DEVICE FOR OPERATING A REACTOR IN AN UNSTABLE STATE

摘要

In order to stabilize a transient instability in a boiling-water reactor, the invention calls for the oscillating neutron flux to be measured and, when it exceeds a first limit over several periods of oscillation, for the rate of increase of the oscillation to be determined. When a further limit (in particular one depending on the rate of increase) of the oscillating flux is exceeded, one of a number of stabilization strategies is selected, as a function of the rate of increase, in order to produce premature stabilization of the oscillation. A hierarchy of stabilization options is available: blocking a power increase in the control system, slow controlled lowering of the power, or rapid power reduction by a partial SCRAM. The unstable condition is monitored by a system of sensors distributed over the reactor core, each of which redundantly measures the flux in a part of the core. The sensors act on several redundantly operating systems, the signal from each sensor being effective in only one of these systems.