Resolution of Generic Safety Issues: Item B-18: Vortex Suppression Requirements for Containment Sumps ( NUREG-0933, Main Report with Supplements 1–34 )
A number of applicants for operating licenses have been performing sump tests to demonstrate ECCS operability during the recirculation phase following a postulated loss-of-coolant accident. These tests have shown that vortex formation is not well-behaved and, as a result, the sump designs in some cases were found to be not adequate. This NUREG-04713 task will develop criteria for sump design with respect to vortex formation and define criteria for sump testing.
This issue is covered in USI A-43, "Containment Emergency Sump Performance."