United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 92-48: Failure of Exide Batteries

                               UNITED STATES
                       NUCLEAR REGULATORY COMMISSION
                   OFFICE OF NUCLEAR REACTOR REGULATION
                          WASHINGTON, D.C. 20555

                               July 2, 1992


NRC INFORMATION NOTICE 92-48:  FAILURE OF EXIDE BATTERIES

Addressees

All holders of operating licenses or construction permits for nuclear power
reactors.

Purpose

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information
notice to inform addressees of failure of a Type GC battery manufactured by
Exide used in safety-related applications and the potential failure of Type
GN batteries used in safety-related applications.  It is expected that
recipients will review the information for applicability to their facilities
and consider actions, as appropriate.  However, no specific action or written
response is required.

Description of Circumstances

On October 7, 1991, Omaha Public Power District reported cracking on the face
of Exide's Class 1E Type GC-23 battery jars installed in February 1980, at
the Fort Calhoun nuclear station (Fort Calhoun), causing leakage of
electrolyte and subsequent inoperability of the battery.

The root cause was attributed to inadequately designed battery terminal post
seals.  The terminal post radial gland seal cracked due to corrosion buildup
which led to cracking on the jar cover and face and subsequent leakage of
electrolyte.

Discussion

Exide discovered the cracking problem in 1982 when the Southern New England
Telephone Company informed Exide that the terminal post seals had cracked on
a Type GW battery purchased from Exide.  Exide's battery Types GC, GN
(nuclear grade) and GW had identically designed terminal post radial gland
seals.  Exide evaluated the problem and determined that the seal between the
cover and terminal posts was inadequately designed.  Corrosion builds up over
time in the seal area at the positive post because electrolyte enters,
becomes trapped, and reacts with the post material.  The corrosion buildup
stresses the seal area and the plastic nut around the seal, and, ultimately,
the cell cover cracks.  Consequently, in 1983, after notifying all holders
of Type GN cells, Exide corrected the design of the seals at the battery
terminal.  However, due to a time lag in the supply chain, batteries received
prior to 1985 may still have been of the old design.  The old design is
characterized by an eight-sided nut around each battery terminal post.

9206260043.                                                            IN 92-48
                                                            July 2, 1992
                                                            Page 2 of 2



On March 24, 1983, the licensee for the Palo Verde nuclear plant notified the
NRC staff of a deficiency in Exide GN batteries involving cracking of the
plastic seals/covers at the terminal posts and electrolyte leakage.  The
notification was based on Exide's service bulletin which addressed this issue
for Type GN batteries and suggested three levels of optional field
modifications (Levels I, II, and III) to repair batteries installed in
nuclear plants.  Fort Calhoun had a Level III repair performed because of
numerous cracks on the battery covers.  The Level III repair technique
creates an all-enveloping secondary cover over the cracked cover.  However,
this repair tends to mask any further cracking until catastrophic battery
failure occurs, as was the case at Fort Calhoun when one-third of the
electrolyte leaked out and the battery had to be replaced.

The NRC wants to inform the nuclear industry that Exide Type GC and GN
batteries received prior to 1985 with an eight-sided nut around each battery
terminal post may be susceptible to corrosion buildup and subsequent cracking
at the positive terminal posts; this condition could ultimately render the
battery incapable of performing its intended safety function. This phenomenon
could occur regardless of whether or not the batteries had the optional field
modifications installed.

This information notice requires no specific action or written response.  If
you have any questions about the information in this notice, please contact
one of the technical contacts listed below or the appropriate Office of
Nuclear Reactor Regulation (NRR) project manager.




                                    Charles E. Rossi, Director
                                    Division of Operational Events Assessment
                                    Office of Nuclear Reactor Regulation


Technical contacts:  Randolph N. Moist: NRR
                     (301) 504-2945

                     Frederick H. Burrows: NRR
                     (301) 504-2901


Attachment:  List of Recently Issued NRC Information Notices
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