United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 85-74: Station Battery Problems

                                                          SSINS No.: 6835 
                                                            IN 85-74       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                            WASHINGTON, DC 20555

                               August 29, 1985

Information Notice No. 85-74:   STATION BATTERY PROBLEMS 

Addressees: 

All nuclear power reactor facilities holding an operating license (OL) or a 
construction permit (CP). 

Purpose: 

This notice describes problems that have occurred with lead-acid station 
batteries at several nuclear power plants. These problems were discovered as
a result of inspections by the NRC Performance Appraisal Team (PAT). It is 
expected that recipients will review the information for applicability to 
their facilities and consider actions, if appropriate, to preclude a similar
problem occurring at their facilities. However, suggestions contained in 
this information notice do not constitute NRC requirements; therefore, no 
specific action or written response is required. 

Description of Circumstances: 

All four recent inspections by the PAT identified problems with lead-acid 
station batteries. Although all of the problems are not listed here, a 
summary of a few of the more significant problems with lead-acid station 
batteries that were identified as a result of these inspections is provided 
below: 

Cooper PAT Inspection (November 1984): 

The battery rated-load discharge test was performed at a discharge rate 
significantly less than the manufacturer's recommended rated-load discharge 
rate for the 8-hour period of the test. The licensee had no records of 
battery charging following the completion of battery discharge test and 
consequently the time and date the batteries were returned to service could 
not be determined. The licensee failed to correct specific gravity 
measurements for electrolyte temperature and level. The licensee had no 
written procedures for conducting charges of the station batteries. 

McGuire PAT Inspection (February 1985): 

Three cells were placed on single-cell chargers for about 2 years, thus 
raising questions regarding the operability of the battery and electrical 
independence and separation of the Class 1E dc power systems. The cells on 
single cell 


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                                                            IN 85-74       
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charge were at voltages higher than specified in the vendor manual. Although
one cell in the battery was jumpered out, the float voltage for the entire 
battery was not reduced; consequently each cell was floated at a voltage 
higher than specified in the battery vendor manual. The battery performance 
discharge test was performed improperly because the test was stopped before 
reaching the minimum specified voltage. 

Susquehanna PAT Inspection (February 1985): 

There were no station procedures for maintaining station batteries in 
accordance with the battery vendor's manual or IEEE Std 450-1975, "IEEE 
Recommended Practice for Maintenance, Testing and Replacement of Large Lead 
Storage Batteries for Generating Stations and Substations" (which is 
endorsed by Regulatory Guide 1.129, "Maintenance, Testing and Replacement of 
Large Lead Storage Batteries for Nuclear Power Plants"). Intercell 
resistance values were not compared with previous values to determine when 
corrective action was required. The licensee did not always conduct 
equalizing charges when required; nor did the licensee have procedures for 
monitoring the progress of an equalizing charge or determining when the 
charge should be terminated. Surveillance procedures for the 60-month 
rated-capacity discharge test did not conform to IEEE Std 450-1975 because 
the test was terminated at the end of 8 hours, instead of when the terminal 
voltage fell to the minimum specified value (usually 1.75 volts per cell). 
The licensee's procedures did not require that the average specific gravity 
be calculated and compared to the technical specification acceptance 
criteria. 

San Onofre PAT Inspection (March 1985): 

During the first 2 years of operation, the battery capacity tests required 
by the Final Safety Analysis Report (FSAR) and IEEE Std 450-1980 were not 
performed on Units 2 and 3. The total battery float voltage was not adjusted
to account for two jumpered out cells. The two jumpered out cells did not 
receive the manufacturer's specified surveillances, maintenance, or charges.
The pilot cells were not being changed on a yearly basis, as recommended by 
the vendor's technical instructions. The station engineer responsible for 
the technical aspects of battery operation, maintenance, and surveillance 
did not receive surveillance results and data sheets on a routine basis. 

Discussion: 

Recent IE inspections of operating facilities indicate that several 
widespread deficiencies may exist in the operation and maintenance of 
station batteries. These deficiencies are attributable to a variety of 
causes, including licensee error, inadequate knowledge of batteries by 
maintenance technicians and supervisors, and inadequate procedural guidance. 
The results of these inspections suggest a general lack of appreciation 
amongst licensee personnel for proper maintenance and surveillance of 
station batteries. Although batteries contain no moving parts, considerable 
care and attention to detail is required to maintain them operable. Too 
often, licensees may be treating these vital engineered safety features 
(ESF) power supplies as "passive" components and not providing them the 
necessary management and technical attention. 
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                                                            IN 85-74       
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The following reference materials, provide guidance as to the individual 
requirements for a facility's station batteries. 

1.   IEEE 450-1975, and 1980 

2.   Regulatory Guide 1.129, Rev. 1, "Maintenance Testing and Replacement of
     Large Lead Storage Batteries for Nuclear Power Plants" (This regulatory
     guide endorses IEEE Std 450-1975 with certain exceptions.) 

3.    Facility Technical Specifications 

4.   Final Safety Analysis Report (FSAR) 

5.   Station Battery Vendor Technical Manual (The vendor's of station 
     battteries periodically update their manuals to include revised 
     guidance.) 

Other recent problems with station batteries were described in IE 
Information Notice 84-83: VARIOUS BATTERY PROBLEMS, November 14, 1984. 

No specific action or written response is required by this information 
notice. If you have questions about this matter, please contact the Regional
Administrator of the appropriate NRC regional office or this office. 


                                   Edward L. Jordan Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  E. W. Weiss, IE
                    (301) 492-9005

                    L. J. Callan, IE
                    (301) 492-9497

Attachment: List of Recently Issued IE Information Notices 
Page Last Reviewed/Updated Tuesday, November 12, 2013