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.