Experimental Validation of CFD Analyses for Estimating the Transport Fraction of LOCA-Generated Insulation Debris to ECCS Sump Screens

Abstract

This paper presents a comparison between computational fluid dynamics (CFD) analysis and experiments in order to help pressurized water reactor (PWR) plants develop a methodology for estimating the amount of insulation debris that may transport to the sump screens of an emergency core cooling system (ECCS). This information is essential for the resolution of Generic Safety Issue-191 on the safety margins of the ECCS systems subsequent to debris accumulation and head loss at the screen.

Tests were carried out on a simulated containment floor in the laboratory to determine the flow velocities in which different types of objects including insulation debris would move along the floor. CFD analyses were independently carried out to determine the flow velocities in the containment under different flow rates and break locations. It was shown that the flow regimes predicted by the CFD analyses compare well with the experimentally observed movement along the floor. Based on this observation the transport fraction of different types of insulation debris can be estimated specific to any PWR plant.