Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 84-83
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
November 19, 1984
Information Notice No. 84-83: VARIOUS BATTERY PROBLEMS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided to alert licensees and applicants of the
potential for significant degradation of safety associated with various
battery related problems. Recipients are expected to review the information
for applicability to their facilities and consider actions, if appropriate,
to preclude similar problems 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:
Overloading D.C. Buses:
At Quad Cities Unit 1 on May 10, 1984, the licensee discovered that the
direct current (dc) power system could no longer provide power to the
connected loads for the time (i.e. , 8 hours) stated in the Final Safety
Analysis Report (FSAR) for postaccident conditions. Over the course of
years, the licensee added new loads to the dc system so the battery would
have been able to provide power only for about 4 hours. The licensee
recognized this condition while preparing to perform a battery discharge
test. The long term solution is to replace the battery with a larger one
sized for the increased loads. Temporarily, the licensee implemented
procedures to limit loads on the dc power system on loss of the battery
chargers.
Solvent Induced Case Cracking:
At the Byron and Braidwood stations in April 1984, 55 instances of battery
case cracking were evaluated by the supplier, GNB Batteries, Inc. The
batteries were NCX-1200 type with styrene-acrylonitrile (SAN) cases that
exhibited crescent shaped cracks at the jar-cover juncture and etching of
the battery side walls. GNB Batteries attributed this cracking to the use of
a solvent, trichloroethylene, used to clean the battery posts of
anti-corrosion (No-ox-id "A") grease during rework of the intercell
connections.
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IN 84-83
November 19, 1984
Page 2 of 3
At Fitzpatrick in March 1983, while at power, the licensee discovered 4
cells leaking on the B train battery and 39 cells exhibiting
non-through-wall cracking in both the A and B train batteries. This
condition necessitated removing and jumpering two cells on the A train,
battery to replace cells on the B train battery. The jumpering was done with
the plant at power and the battery chargers carrying the dc loads.
Subsequent investigation by the manufacturer, GNB Batteries, Inc. (then
known as Gould, Inc.), suggested that the cracking was caused by the
application of hydrocarbon-based grease to the vinyl straps on the battery
racks, presumably to permit the cells to slide over the racks more easily
and facilitate installation of the cells. The hydrocarbon oil in the grease
acted like a solvent and attacked the cell cases which were made of SAN.
Ultimately, all of the cells had to be replaced.
Discussion:
In general, matters related to the integrity of the Class 1E dc power system
and its batteries are important to safety because complete loss of dc power
would place a nuclear power plant in an unanalyzed condition.
Although the addition of a small dc load may be accomplished by use of
margin between the original design loads and the battery capacity, the
cumulative effect of a number of small loads added over an extended period
of time may overload the dc bus. The event at Quad Cities occurred because
the licensee added loads to the Class 1E battery without analyzing the
effect and comparing the results to the commitments in the FSAR regarding
design margin for battery performance.
A cracked battery case can cause loss of electrolyte and, consequently,
reduce battery capacity or cause a short to ground. Although it may not
occur instantaneously, complete loss of electrolyte in a single cell could
open the battery circuit and cause loss of the entire battery. As
illustrated by the event at Fitzpatrick, the loss of electrolyte because of
solvent induced case cracking may go undetected, despite routine
surveillance tests, and result in loss of a battery while the plant is at
power.
Besides GNB Batteries, Inc., other manufacturers also warn against use of
solvents or solvent-containing substances near battery cases or covers.
Licensees may wish to review their maintenance and surveillance procedures
for station batteries to ensure that the use of solvents in the vicinity of
batteries is carefully monitored and in accordance with procedures approved
by the battery manufacturer's service department. Tests have shown that some
commonly used solvents will induce almost instantaneous cracking of battery
cases. Some battery manufacturers have advised us that the use of a solvent
is not necessary to remove anti-corrosion grease from a battery terminal.
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IN 84-83
November 19, 1984
Page 3 of 3
Although not specifically addressing the use of solvents on battery cases,
Regulatory Guide 1.128, "Installation Design, and Installation of Large Lead
Storage Batteries for Nuclear Power Plants," and Regulatory Guide 1.129
"Maintenance, Testing, and Replacement of Large Lead Storage Batteries for
Nuclear Power Plants," provide useful information on these subjects.
No specific action or written response is required by this information
notice. If you need additional information 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: Eric Weiss, IE
(301) 492-9005
Attachment: List of Recently Issued IE Information Notices
