Assessment of an X-ray analysis system for investigating of fibrous debris bed formation on PWR sump strainer modules

During the blow-down stage of a loss of coolant accident (LOCA), fibrous material and associated debris are transported from the location of the pipe break to the sump system as core coolant flows through containment. A series of strainer modules are installed to restrict large debris from entering the sump system, which supplies coolant to the Emergency Core Cooling System (ECCS). The accumulation of fibrous and debris material can result in the formation of semi-porous layers on the strainer module surfaces and possibly result in a reduction of coolant recirculation to the ECCS. The University of New Mexico (UNM) is investigating non-invasive techniques to better visualize the formation of fibrous debris beds on sump strainer modules; real-time visualization of debris bed formation would allow for better assessment of the filtration blockage of sump strainers. A series of exploratory tests were performed at the Center for Non-Destructive Evaluation (CNDE) at Iowa State University (ISU) to determine the viability of using an X-ray system to perform in situ measurements of debris bed formation and particulate filtration on small-scale representative sump pump strainer assemblies.