Abstract: The invention is principally directed to a reduced order model, XEDOR, facilitating the prediction of and the diagnostics of pellet-clad interaction stress-corrosion-cracking failure of nuclear fuel rods. The invention more particularly relates to assessment of susceptibility to PCI failure for guidance in the design of fuel loading in nuclear reactors. The invention additionally relates to the protection against PCI failure by providing operational information to operators of a nuclear reactor during power maneuvering, including predictive calculations prior to executing power maneuvers. Additionally, the invention relates to the diagnostics of an event suggesting a possible PCI cladding failure.

Abstract: The invention is principally directed to a reduced order model, XEDOR, facilitating the prediction of and the diagnostics of pellet-clad interaction stress-corrosion-cracking failure of nuclear fuel rods. The invention more particularly relates to assessment of susceptibility to PCI failure for guidance in the design of fuel loading in nuclear reactors. The invention additionally relates to the protection against PCI failure by providing operational information to operators of a nuclear reactor during power maneuvering, including predictive calculations prior to executing power maneuvers. Additionally, the invention relates to the diagnostics of an event suggesting a possible PCI cladding failure.

Abstract: The present invention provides a method of operating a Boiling Water Reactor, having the steps of analyzing LPRM signals for oscilliatory behavior indicative of neutron-flux-coupled density wave oscillations, determining if oscilliatory behavior is present in the signals; initiating a reactor protective corrective action if the oscilliatory behavior is determined, and in addition, initiating corrective actions if neutron uncoupled oscillations are possible. Detecting the later is performed through analytically determined exclusion zone on the power flow map or by on-line stability calculations for several high power channels.

Abstract: A new method for stabilizing the regional mode power/flow oscillations in a boiling water reactor core is introduced in this invention. The method depends on introducing flow resistance or partitions in the common flow plena (upper core plenum and/or lower plenum). The said resistance or partitions function to reduce or prevent the flow communication between any two groups of fuel assemblies through the common plena, thus preventing the excitation of the neutron flux first azimuthal harmonic mode. The partition devices of this invention, which provide the flow resistance, must divide the flow area in a common core plenum into three or more flow paths, as dividing the plenum in two flow paths only would not prevent the instability but would simply result in re-orienting the instability neutral line dividing the core assemblies into two sides oscillating out-of-phase.