ML20056F695
| ML20056F695 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/18/1993 |
| From: | Cross J PORTLAND GENERAL ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEIN-93-025, IEIN-93-25, NUDOCS 9308300277 | |
| Download: ML20056F695 (4) | |
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Portland General BectricCompany James E. Cross Vice President and Chief Nuclear Officer August 18, 1993 Trojan Nuclear Plant Docket 50-344
'.*rense NPF-1 U.
S.
Nuclear Regulatory Commission Attn:
Document Ccntrol Desk f
Washington, DC 20555
Dear Sir:
Clarification to Information in Information Notice 93-25 Portland General Electric (PGE) has performed a review of NRC Information Notice 93-25, Electrical Penetration Assembly Degradation dated April 1,
1993.
The purpose of this correspondence is to provide some clarification to the Trojan Nuclear Plant-specific information contained in the Information i
Notice.
PGE's comments are enclosed as an attachment to this letter.
If you have any questions regarding this matter, please contact Tom Walt at (503)S56-7558.
Sincerely, M
Attachment c:
Mr. Bobby H.
Faulkenberry Regional Administrator, Region V U.S. Nuclear Regulatory Commission Mr. David Stewart-Smith State of Oregon Department of Energy Mr.
J.
F. Melfi NRC Resident Inspector Trojan Nuclear Plant k[s
> % **) h t^.4 930830027 930818 PDR ADOC 05000344
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1?1 S W snm Dwl Pot'd Oegon 27204 (503)464-8897
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Trojan Nuclear Plant Document Control Desk l
Docket 50-344 August 18, 1993 r
License NPF-1 Attachment Page 1 of 3
't CLARIFICATION TO INFORMATION IN Information Notice 93-25 1.
Statement:
In July 1987 and in October 1989... PGE reported problems with containment air leakage...[ licensee event reports 50-i 344/87-011...]
Clarification:
Licensee Event Report 50-344/87-011 was submitted on June 11, 1987, not July 1987.
2.
Statement:
On October 28, 1991, while the plant was in a refueling outage, the licensee reported to the NRC that in the originally installed electrical penetration assemblies, the seal (polyurethane) and lubricant (Celvacene or Glycerine) materials were inappropriate for the application (LER 91-t 011-01).
Clarification:
i During review of this Information Notice, we were unable to l
find evidence that the seal manufacturer recommended use of i
i Celvacene as a lubricant.
Celvacene is specified as a lubricant for the flange (header plate) 0-rings, not the electrical conductor module seals in the Architect / Engineer Instruction Manual for Electric Penetration Seals.
There have been instances in which Celvacene-type residue was found on seals.
The origin of the residue in unknown, but believed to be the result of cross-contamination / misuse of Celvacene.
While glycerine is the approved lubricant, it is possible for the glycerine to become contaminated with water. It is generally accepted that the presence of water i
is detrimental to polyurethane.
Degradation of the seals is attributed to inappropriate seal material (polyurethane).
F Trojan Nuclear Plant Document Control Desk Docket 50-344 August 18, 1993 i
License NFF-1 Attachment i
Page 2 of 3 3.
Statement:
)
The licensee subsequently replaced all the Bunker-Ramo j
electrical penetration assemblies with Conax assemblies.
l i
Clarification:
As described in Licensee Event Report 50-344/91-011-01, several Electrical Penetration Assemblies containing safety-related cables were replaced with assemblies of another type (Conax).
Upgrade modifications were implemented on the 1
remaining Bunker-Ramo type assemblies.
These modifications include installation of replacement seals of a more durable material; installation of an additional 0-ring seal to affected assemblies; and upgrade of the nitrogen system to supply safety-grade nitrogen to those remaining Amphenol-Bunker Ramo assemblies containing safety-related conductors.
4.
Statement:
The Bunker-Ramo electrical penetration assembly consists of a cylindrical structure with header plates at each end.
One header plate is designed to be bolted to a flange on the containment liner plate penetration nozzle.
Containment integrity is achieved by two C-cup seals between flanges.
Clarification:
There is a circular header plate at only one end.
The unitized header assembly is installed at the end of the nozzle outside containment.
(Electrical penetrations consist of carbon steel pipe " sleeves" embedded in the containment wall with appropriate gusset plates and stiffeners for transferring loads to the containment wall.
The liner plate at the penetration is thickened to transfer l
the assembly loads to the containment wall.
The penetration sleeves protrude from the plane of the liner i
plate and are termed " nozzles".)
Each penetration assembly consists of a pressure boundary combined in a unitized header plate with hermetically sealed conductor penetrations and internal conductors.
5.
Statement:
Each electrical penetration assembly has two seals, an outer one, nominally of 8.9 cm. diameter, and an inner one, of nominally 6.4 cm.
Clarification:
The.tnboard and outboard seals for a given assembly have the saan diameter.
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e Trojan Nuclear Plant Document Control Desk Docket 50-344 August 18, 1993 License NPF-1 Attachment Page 3 of 3 6.
Statement:
The simultaneous effects of corrosion and moisture at normal temperature had not been taken into account.
Clarification:
The root cause of the cup seal failures was use of an inadequate material, which tended to take a compression set and had low age resistance.
Contributing to compression set and aging is the presence of water and other polar fluids, which causes hydrolysis of the polymer.
Corrosion is not considered to be a major contributor to degradation of the cup seals.
7.
Statement:
In 1987, the licensee determined that three seals had failed because they were erroneously lubricated with an f
incompatible (silicone) grease.
Clarification:
Licensee Event Report 87-011-00 attributes failure of the se.al to " permanent compressed displacement of the seals due to age".
A 1991 report from an independently performed root-cause determination indicated that "use of silicone lubricant may not damage polyurethane, but this was not in accordance with-procedure."
9.
Statement:
After examination of seal failures... Parker determined that 1
the failed seals had castor oil residue... indicative of the use of Celvacene.
Celvacene, specified for use by the original penetration supplier...
I Clarification:
PGE was unable to locate documentation indicating that the i
original penetration manufacturer or the Architect / Engineer recommended the une of Celvacene for the module seals.
Glycerine was recommended for the module seals and Celvacene was recommended for flange 0-rings in the Architect / Engineer Instruction Manual for Electric I
Penetration Assemblies.
The' origin of the Celvacene residue found on the seals is unknown, but likely to be the result of cross-contamination / misuse of Celvacene.
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