United States Nuclear Regulatory Commission - Protecting People and the Environment

Survey and Evaluation of System Interaction Events and Sources: Main Report and Appendices A and B (NUREG/CR-3922, ORNL/NOAC-224, Volume 1)

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Publication Information

Manuscript Completed: December 1984
Date Published:
January 1985

Prepared by:
G.A. Murphy
Nuclear Operations Analysis Center
Oak Ridge National Laboratory
Oak Ridge, Tennessee 37831

M.L. Casada, M.D. Muhlheim, M.P. Johnson, J.J. Rooney, J.H. Turner
JBF Associates, Inc.
1000 Technology Park Center
Knoxville, Tennessee 37932

Prepared for:
Division of Safety Technology
Office of Nuclear Reactor Regulation
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC FIN B-0789

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Abstract

This report describes the first phase of an NRC-sponsored project that identified and evaluated system interaction (SI) events that have occurred at commercial nuclear power plants in the United States. The project included (1) an assessment of nuclear power plant operating experience data sources, (2) the development of search methods and event selection criteria for identifying system interaction events, (3) a review of possible events, and (4) a final evaluation and categorization of the events. The report, organized in two volumes, outlines each of these steps and presents the results of the project.

The results include 235 events identified as adverse system interactions and 23 categories into which those events were assigned. The categories represent groups of similar events and include areas such as: adverse interactions between normal or offsite power and emergency power systems; degradation of safety systems by vapor or gas intrusion; degradation of safety-related equipment by fire protection systems; and flooding of safety-related equipment through plant drain systems. After evaluating each category (and the events contained in them), the project made two major recommendations: the safety significance of each category with emphasis on the potential for continued problems in these areas should be examined; and current system interaction analysis methods should be studied to determine their effectiveness for identifying system interaction events.

Volume 1 contains an introduction to the project, describes the process by which the project identified and evaluated the system interaction events, and presents the results and recommendations from that evaluation. Volume 1 also contains appendixes that review the data sources used in identifying events and outlines the information collected for each event. Volume 2 provides a description of each adverse system interaction event and lists the references for the events.

Phase II of this project, "Evaluation of System Interaction Methods," will assess the effectiveness of current methods using the events identified in this report.

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