BWR ECCS Pump Suction Concerns following a LOCA (NUREG-2196)

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Publication Information

Manuscript Completed: February 2016
Date Published: May 2016

Prepared by:
W.J. Krotiuk, C. Boyd, T. Zaki, W. WangOffice

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

This document describes a method to perform a plant-specific assessment to determine whether an emergency core cooling system (ECCS) pump will operate acceptably following a loss-of-coolant accident (LOCA) in a boiling water reactor (BWR) pressure suppression pool. The assessment approach uses the ECCS pump strainer location, the ECCS pump operation criteria, the ECCS pump startup and full operation timing information, and an estimate of the transient pool void fraction information to make the determination.

To support the developed assessment method, this report describes the acceptable ECCS pump operating range necessary to prevent pump damage if noncondensable gas ingestion occurs or to permit recovery from noncondensable gas ingestion. Additionally, this report uses computational fluid dynamics (CFD) analyses to define a noncondensable gas bubble "exclusion zone" and to provide the time-dependent noncondensable void fraction distribution in the suppression pool outside the large gas bubble following a LOCA. The report also lists the test facilities used to test BWR pressure suppression systems and summarizes the available test data that are used to verify the acceptability of the CFD analyses.