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-0471[1] 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."
[1] NUREG-0471, "Generic Task Problem Descriptions (Categories B, C, and D)," U.S. Nuclear Regulatory Commission, June 1978.
Page Last Reviewed/Updated 06/24/2025