Knowledge Base for the Effect of Debris on Pressurized Water Reactor Emergency Core Cooling Sump Performance (NUREG/CR-6808,LA-UR-03-0880)

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Publication Information

Manuscript Completed: February 2003
Date Published:
February 2003

Prepared by:
D.V. Rao, Principal Investigator
Probabilistic Risk Analysis Group (D-11)
Los Alamos National Laboratory
Los Alamos, New Mexico 87545

C.J. Shaffer
ARES Corporation (Subcontractor)
851 University Boulevard, SE, Suite 100
Albuquerque, New Mexico 87106

M.T. Leonard
dycoda, LLC (Subcontractor)
70 Andres Sanchez Boulevard
Belen, New Mexico 87002

K.W. Ross
Innovative Technology Solutions Corporation (Subcontractor)
6000 Uptown Boulevard, NE, Suite 300
Albuquerque, New Mexico 87110

B.P. Jain, NRC Project Manager

Prepared for:
Division of Engineering Technology
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code Y6041

Availability Notice


This report describes the substantial base of knowledge that has been amassed as a result of the research on boiling-water reactor (BWR) suction-strainer and pressurized-water reactor (PWR) sump-screen clogging issues. These issues deal with the potential insulation and other debris generated in the event of a postulated loss-of-coolant accident within the containment of a light-water reactor and subsequently transport to and accumulation on the recirculation sump screens. This debris accumulation could potentially challenge the plant's capability to provide adequate long-term cooling water to the emergency core cooling system (ECCS) and the containment spray system pumps.

This report describes analytical and experimental approaches that have been used to assess the different aspects of sump and strainer blockage and to identify the strengths, limitations, important parameters and plant features, and appropriateness of the different approaches. The report is organized in the same order that an evaluation of the potential of sump screen blockage would be performed. The report provides background information on the issues, including significant United States regulatory developments regarding the resolution of the issue. The report is designed to serve as a reference for plant-specific analyses with regard to whether a sump or strainer would perform its function without preventing the operation of the ECCS pumps.

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