Patent ID: 8135106
Filing Date: 2012-03-13
Classification: G21C,G21D,Y02E

Abstract:
1. A method of operating a Boiling Water Reactor comprising: a step of analyzing Local Power Range Monitor signals in the Boiling Water Reactor for oscillatory behavior indicative of neutron-flux-coupled density wave oscillations; determining if oscillatory behavior is present in the signals; and initiating a first reactor protective corrective action if the oscillatory behavior is determined to be present; and if the Local Power Range Monitor signals analyzed in the step of analyzing Local Power Range Monitor signals are not oscillatory beyond noise levels, a step of anticipating and suppressing instability in the Boiling Water Reactor caused by single channel thermal-hydraulic density waves in at least one fuel channel of the Boiling Water Reactor, wherein the single channel thermal-hydraulic density waves are uncoupled from neutron flux variations; the step of anticipating and suppressing the instability comprising performing analytical simulations of the Boiling Water Reactor, independent of neutron flux; the analytical simulations identifying relationships between output power of the Boiling Water Reactor and coolant flow in the Boiling Water Reactor that result in the single channel thermal-hydraulic density waves in the at least one fuel channel of the Boiling Water Reactor; thereby defining a boundary of an exclusion zone on a power-coolant flow operating map of the Boiling Water Reactor where neutron-flux-uncoupled density wave oscillations are possible in the at least one fuel channel of the Boiling Water Reactor; determining whether operating power and coolant flow in the Boiling Water Reactor are within the exclusion zone of the power-coolant flow operating map of the Boiling Water Reactor while the Local Power Range Monitor signals are not oscillatory beyond noise levels; initiating a second reactor protective corrective action if the operating power of the Boiling Water Reactor and coolant flow in the Boiling Water Reactor are within the exclusion zone of the power-coolant flow operating map; and repeating at least the step of analyzing Local Power Range Monitor signals if the operating power of the Boiling Water Reactor and coolant flow in the Boiling Water Reactor are outside the exclusion zone of the power-coolant flow operating map.