ML20085D497

Part 21 Rept Re Cracking in Casing of Exide Type GC-23 Batteries Produced Prior to 1983.Initially Reported on 911003.Caused by Inadequate Design of Cell Terminal Post Seals.Use of pre-1983 Subj Batteries Discontinued

ML20085D497
Person / Time
Site:	Fort Calhoun
Issue date:	10/07/1991
From:	Gates W OMAHA PUBLIC POWER DISTRICT
To:	Martin R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
REF-PT21-91 LIC-91-259R, NUDOCS 9110160228
Download: ML20085D497 (3)

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Omaha Pub!!c Power District October 7, 1991 444 South 16th Street Mall Lir #1-25IA Omana, Nebraska 68102-2247 402/636-2000 Mr. Robert D. Martin Regional Administrator U. 5. NL;. lear Regulatory Commission Region.IV 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011

Reference:

Docket No. 50-285 l Gentlemen:

SUBJECT:

10 CFR Part 21 Report ; ing Exide Type GC-23 Batteries y

Omaha Public Power Dirtrict (0 PPD) has investigated a cracking phenomenon in the casings of Exide Tyre GC-23 batteries installed at fort Calhoun Station and determined it to be ieportable pursuant to 10 CFR Part 21. OPPD notified Mr. P. H. Harrell of the Region IV office on October 3,1991 of the attached information. Attached is i n fo r .. 'on required pursuant to 10 CFR Part 21.21(b)(3).

If you should have any questions, please contact me.

Sincerely, A&'. 5/N4 W. G. Gates Division Manager Nuclear Operations l

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c: LeBoeuf, Lamb, Leiby & fiacRae l Dr. T. E. Murley, Director of Reactor Regulation (3)

W. C. Wal'er, NRC Project Manager R. P. Mullikin NRC Senior Resident Inspector Document Control Desk l

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w 4-a INTRODUCTION This report applies to Exide Type GC-23 batteries with radial gland. post seals that were produced prior to 1983. In 1983, Exide sent written documentation to nuclear utilities and to the Nuclear Regulatory Commission, which provided information about cracking caused by corrosion

)ropagating from the positive terminal seal nut in pre-1983 Type GN 3attery cells. OPPD has found no document tion that the Type GC-23, nor cracking on the jar face resulting in the loss of electrolyte, had been reported to the NRC pursuant to 10 CFR Part 21.

Two, 58-cell.Exide lead-calcium plate, type GC 23 storage batteries were installed at Fort Calhoun Station in 1980. The batteries are comprised of jars, each of which co:tain two battery cells. On July 1.- 1991, a security guard noticed electralyte on the floor of the East Battery Room (Room 54). Further investigation by Operations personnel found the source of the electrolyte tc be a crack on the side of the jar for cell #15 in Battery #1 (EE-8A) . This cracked battery Jar was replaced on July 16, 1991. OPPD verbally notified Yuasa ~ Exide Inc. on August 29, 1991, informing Mr. Ira Baeringer - Vice President of Engineering, of OPPD's intent to: conduct an evaluation of the cracking phenomenon to determine whether it could create a substantial safety hazard pursuant to 10 CFR Part 21.

On September 11, 1991, a loss of electrolyte from cell #17 in Battery #1-was discovered. The loss was determined to be caused by scimitar cracking on the face of the battery jar. The jar was replaced on September 12, 1991; however, due to the indeterminate status of the effect of the cracking phenomenon on the batteries, both batteries were declared inoperable and a plant shutdown was initiated.

NATURE OF DEFF" The root cause of the cracking seen in Battery #1, Cells #15 and #17 has been attributed to an inadequate desinn of the cell terminal post seals.

The design did not adequately allow for the build-up of corrosion products at the positive termintl. This typr of corrosion is a well documented phenomenon in aaed Type GN batterie/ that were manufactured by Exide piior to 1983 which had a " 3ost -lock" desig'n. The corrosion-takes place in the crevice area c eatec in the nositive post terminal seal area. The

, resulting corrosion product is :alled " nodular" corrosion composed of lead oxide-and lead sulfate) ana grows radially outward from (the positive terminal post creating increasing stresces on the plastic components of the cell' cover ud jar, which eventually produces cracking in the jar.

The stresses produced from thermal cycling of the jars are negligible in comparison to the- stresses produced by the corrosion products.

Furthermore, aging embrittlement of the polycarbonate jars has been determined to be an insignificant factor relative to crack propagation.

In the cases of the Battery #1, cells #15 and '#17 failures, a terminal post seal crackad leading to cracking of- the positive terminal seal nut.

As the stresscs continued to increase with further nodular corrosion product growth, a driving mechanism was achieved for cracking on the jar top to propagate from the seal nut to the edge of the jar and eventually progressing as a crack on the side or face of the jar. This sic le or face cracking resulted in the loss of electrolste.

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The history of cracks in the Fort Calhoun Station batteries supplied by-

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Exide' dates back to11982 when cracking started to-appear in the battery tops-or covers. The'GC-23 batteries were installed in 1980. Exide began manufacturing the G-type batteries (GN and-GC) in late 1977/early 1978.

Both the GC and GN batteries originally had identical " post-lock" terminal posts gland. seals that neither prevented nor allowed for the' build-up of corrosion products at the positive terminal. In--1983. Exide introduced new GC and GN battery cells that-have a " sliding-lock" 0-ring seal, which allowed-positive terminal post nodular corrosion growth.

IDENTIFICATION OF SUPPLIER The Fort: Calhoun Station batteries were purchased under 0 PPD Purchase Order No. 44643 in E August 1979 for Modification MR FC-79-03. NRC

. Regulation 10 CFR Part 21 was applicable to the purchase of the batteries.-

li the requirements-section a minimum battery life expe(ctancy of 20 years was -quoted.5.03) of the spec The service.

life requirement was confirmed wdth the supplier. The batteries.at Fort

-Calhoun Station have been in ser ice for 11 years. The current corporate address of the. supplier of the batteries is:

-Yuasa Exide-Incorporated 645 Penn Street P.O. Box 14145 Reading, PA 19601 LOCATION OF CONPONENTS IN USE

The suspect batteries ;were replaced in September 1991 and- there are no pre-1983 Exide Type-GC-23 batteries currently in use at the Fort Calhoun Station.

CORRECTIVE ACTIONS Due to the indeterminate status of the:effect of the cracking phenomenon on the operability of the-station batteries, both batteries were declcred

-inoperable on September 12,- 1991, and a plant-shutdown was initiated. The

_ suspect batteries have been replaced and -there are no pre-1983 Exide Type -

GC-23 batteries currently'in use at the Fort-Calhoun Station, 4

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