Abstract: Filtering systems and methods remove debris from coolant in a nuclear reactor setting. One or more filters are installed outside coolant reservoirs specifically where coolant will flow toward the reservoir, such as during a transient or other coolant leak event. Useable filters permit coolant through-flow while catching, straining, diverting, or otherwise removing debris from the coolant without significant interference with the coolant flow. Filters can be installed at any location in a flow path for coolant flowing toward the reservoir, including pipes draining into a suppression pool, floor or personnel platform gratings, areas around main steam legs or steam generators, in a reactor drywell, etc. One or more filters are installed by securing the filter in a coolant flow path into a coolant source. Installation and maintenance can be performed during any maintenance period.

Abstract: Filtering systems and methods remove debris from coolant in a nuclear reactor setting. One or more filters are installed outside coolant reservoirs specifically where coolant will flow toward the reservoir, such as during a transient or other coolant leak event. Useable filters permit coolant through-flow while catching, straining, diverting, or otherwise removing debris from the coolant without significant interference with the coolant flow. Filters can be installed at any location in a flow path for coolant flowing toward the reservoir, including pipes draining into a suppression pool, floor or personnel platform gratings, areas around main steam legs or steam generators, in a reactor drywell, etc. One or more filters are installed by securing the filter in a coolant flow path into a coolant source. Installation and maintenance can be performed during any maintenance period.

Abstract: A method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at low core flows is described. The operating domain is characterized by a map of the reactor thermal power and core flow. In an exemplary embodiment, the method for expanding the operating domain of a boiling water nuclear reactor permits operation of the reactor between about 120 percent of rated thermal power and about 85 percent of rated core flow to about 100 percent of rated thermal power and about 55 percent of rated core flow. The method includes determining an elevated load line characteristic that improves reactor performance, performing safety evaluations at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations at the elevated load line. The method also includes defining a set of operating conditions for the reactor in an upper operating domain characterized by the elevated load line.

Abstract: A nuclear reactor core is provided that includes a plurality of fuel assemblies. In an exemplary embodiment, each fuel assembly includes a main coolant flow channel having an inlet. The plurality of fuel assemblies are arranged into at least three regions within the core. The flow channels are configured so that the flow of coolant through the main coolant flow channels of the fuel assemblies located in a particular region are substantially the same, and that the coolant flow through the fuel assemblies in each region is different from the coolant flow through the fuel assemblies in each other region.

Abstract: A computerized method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at core flows lower than normal operating parameters is provided. The operating domain is characterized by a map of the reactor thermal power and core flow. The computerized method includes determining by computer simulation a load line characteristic that is elevated over normal operating parameters and that increases reactor performance over normal operating parameters, performing safety evaluations by computer simulation at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations by computer simulation at the elevated load line.

Abstract: A method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at low core flows is described. The operating domain is characterized by a map of the reactor thermal power and core flow. In an exemplary embodiment, the method for expanding the operating domain of a boiling water nuclear reactor permits operation of the reactor between about 120 percent of rated thermal power and about 85 percent of rated core flow to about 100 percent of rated thermal power and about 55 percent of rated core flow. The method includes determining an elevated load line characteristic that improves reactor performance, performing safety evaluations at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations at the elevated load line. The method also includes defining a set of operating conditions for the reactor in an upper operating domain characterized by the elevated load line.

Abstract: A computerized method for expanding the operating domain of a boiling water nuclear reactor that permits safe operation of the reactor at core flows lower than normal operating parameters is provided. The operating domain is characterized by a map of the reactor thermal power and core flow. The computerized method includes determining by computer simulation a load line characteristic that is elevated over normal operating parameters and that increases reactor performance over normal operating parameters, performing safety evaluations by computer simulation at the elevated load line to determine compliance with safety design parameters, and performing operational evaluations by computer simulation at the elevated load line.