United States Nuclear Regulatory Commission - Protecting People and the Environment

GSI-191 Technical Assessment: Development of Debris Generation Quantities In Support of the Parametric Evaluation (NUREG/CR-6762, Volume 3)

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Publication Information

Manuscript Completed: November 2001
Date Published: August 2002

Prepared by:
D. V. Rao, C. Shaffer*
S. Ashbaugh

Los Alamos National Laboratory
Los Alamos, NM 87545

*ARES Corporation
851 University Blvd. S.E.
Albuquerque, NM 87106

M. L. Marshall, 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

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This report documents the debris generation analysis that supported a parametric evaluation of operating U. S. pressurized water reactors (PWR) plants to access whether or not Emergency Core Cooling Systems (ECCS) recirculation sump failure is a plausible concern. This evaluation was part of the Nuclear Regulatory Commission (NRC) Generic-Safety-Issue (GSI) 191 study tasked to determine if the transport and accumulation of debris in a containment following a loss-of-coolant accident (LOCA) will impede the operation of the ECCS in operating PWRs. The parametric evaluation identified a range of conditions in which PWR ECCS could fail in the recirculation mode of operation. These conditions stem from the destruction and transport of piping insulation materials, containment surface coatings (paint), and particulate matter (e.g., dirt) by the steam/water jet emerging from a postulated break in reactor coolant piping. The methodology used to estimate quantities of insulation debris generated by a LOCA depressurization jet was an essential part of the parametric evaluation. This report documents the methodology, assumptions, and data used to determine the quantities of debris generated that were used in the parametric evaluation.

The plant-specific data, required for credible debris generation estimates, were limited for most plants. The evaluation performed detailed debris generation estimates for a volunteer plant where the data was readily available and then the limited insulation data of the other plants were used to essentially scale the results of the volunteer plant to each of these other plants. Substantial uncertainty associated with the debris generation estimates is inherent due to the complexity of the analysis and the availability of appropriate data. Due to limitations of information, these estimates are not considered best-estimate plant-specific values. Instead, they represent a credible range of debris generation estimates for the industry as a whole.

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