United States Nuclear Regulatory Commission - Protecting People and the Environment

Testing to Evaluate Extended Battery Operation in Nuclear Power Plants (NUREG/CR-7188)

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Publication Information

Manuscript Completed: October 2014
Date Published: May 2015

Prepared by:
W. Gunther, G. Greene, Y. Celebi, K. Sullivan and J. Higgins

Brookhaven National Laboratory
Nuclear Science and Technology Department
Systems Engineering Group
Upton, NY 11973-5000

Liliana Ramadan, NRC Project Manager

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

Availability Notice


The Japanese earthquake and tsunami event on March 11, 2011, illustrated the fact that restoration of the alternating current (AC) power supply at nuclear power plants (NPPs) can be significantly impacted by external events and can take a longer time to recover under certain scenarios. Therefore, a lesson learned from the Japanese event that may be applicable to U.S. NPPs is the need to examine the extended loss of alternating current power (ELAP) conditions and determine if the existing vented lead acid batteries can function beyond their defined design basis (or beyond-design basis if existing Station Blackout (SBO) coping analyses were utilized) duty cycles in order to support core cooling. The NRC’s Office of Nuclear Regulatory Research sponsored testing to evaluate the battery’s performance availability and capability to supply the necessary direct current (DC) loads to support core cooling and instrumentation requirements for extended periods of time. Plant profiles from four NPPs [3 Pressurized Water Reactors (PWRs) and 1 Boiling Water Reactor (BWR)] were obtained from the nuclear industry through the Nuclear Energy Institute (NEI) and were used for this test program. The testing provided an indication of the amount of time available (depending on the actual load profile) for batteries to continue to supply core cooling equipment beyond the original duty cycles for a representative plant. Testing also demonstrated that battery availability can be significantly extended using load shedding techniques to allow more time to recover AC power. The projected availability of a battery can be accurately calculated using the IEEE Standard 485-2010, “IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications,” or using the empirical algorithm described in this report. This report provides detailed test results and analysis regarding the battery’s performance availability and capability for the tested load profiles.

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