Information Notice 1993-25, Electrical Penetration Assembly Degradation

Electrical Penetration Assembly Degradation

ML031080020
Person / Time
Site:	Beaver Valley, Millstone, Hatch, Monticello, Calvert Cliffs, Dresden, Davis Besse, Peach Bottom, Browns Ferry, Salem, Oconee, Mcguire, Nine Mile Point, Palisades, Palo Verde, Perry, Indian Point, Fermi, Kewaunee, Catawba, Harris, Wolf Creek, Saint Lucie, Point Beach, Oyster Creek, Watts Bar, Hope Creek, Grand Gulf, Cooper, Sequoyah, Byron, Pilgrim, Arkansas Nuclear, Three Mile Island, Braidwood, Susquehanna, Summer, Prairie Island, Columbia, Seabrook, Brunswick, Surry, Limerick, North Anna, Turkey Point, River Bend, Vermont Yankee, Crystal River, Haddam Neck, Ginna, Diablo Canyon, Callaway, Vogtle, Waterford, Duane Arnold, Farley, Robinson, Clinton, South Texas, San Onofre, Cook, Comanche Peak, Yankee Rowe, Maine Yankee, Quad Cities, Humboldt Bay, La Crosse, Big Rock Point, Rancho Seco, Zion, Midland, Bellefonte, Fort Calhoun, FitzPatrick, McGuire, LaSalle, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant
Issue date:	04/01/1993
From:	Grimes B Office of Nuclear Reactor Regulation
To:
References
IN-93-025, NUDOCS 9303250146
Download: ML031080020 (12)

I'- '

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, D.C. 20555 April 1, 1993 NRC INFORMATION NOTICE 93-25: ELECTRICAL PENETRATION ASSEMBLY DEGRADATION

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 alert addressees to problems that could result in degradation of

electrical penetration assembly seals. This information notice focuses on the

containment integrity function of these seals. It is expected that recipients

will review the information for applicability to their facilities and consider

actions, as appropriate, to avoid similar problems. However, suggestions

contained in this information notice are not NRC requirements; therefore, no

specific action or written response is required.

Description of Circumstances

In July 1987 and in October 1989, the licensee for the Trojan Nuclear Plant, the Portland General Electric Company, reported problems with containment air

leakage through its Bunker-Ramo electrical penetration assembly seals

[licensee event reports (LERs) 50-344/87-11 and 50-344/89-23]. In July and

August 1991, the NRC inspected the use of containment electrical penetration

assembly seals at Trojan and concluded that the licensee had not established

an effective program for trending and evaluating electrical penetration

assembly seal leakage (Inspection Report 50-344/91-27). 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 Glycerin) materials were

inappropriate for the application (LER 50-344/91-11-01). The licensee

concluded that these materials may cause seal degradation and that the seals

may become degraded if subjected to design basis accident conditions for

moisture or temperature. The licensee replaced the electrical penetration

assembly seal with an environmentally qualified ethylene propylene rubber seal

and added a silicone rubber backup O-ring to the outer face of each electrical

penetration assembly module. The licensee subsequently replaced all the

Bunker-Ramo electrical penetration assemblies with Conax assemblies.

Discussion

Electrical penetration assemblies provide electrical continuity for field

cables penetrating the containment and maintain containment integrity.

9303250146 - PW a: f1) t arC;02S ISoC'aoI

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IN 93-25 April 1, 1993 Degraded electrical penetration assemblies can adversely affect containment

integrity by allowing excessive leakage from the containment under accident

conditions.

The Bunker-Ramo electrical penetration assembly consists of a cylindrical

structure with circular 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 the

flanges. In the Bunker-Ramo design, a helical spring-loaded polyurethane seal

is mounted at each end of the-electrical penetration assembly. Each

electrical penetration assembly has two seals, an outer one, nominally of

8.9 cm [3.5 inch] diameter, and an inner one, of nominally 6.4 cm [2.5 inch]

diameter. The outer seal functions as part of the containment boundary while

the inner seal functions as an outer seal test pressure boundary. The

electrical penetration assembly header plate is equipped with a connection to

which a pressure indicating gauge can be attached to monitor seal leakage.

At the Trojan plant, the qualified life of the seal had not been accurately

established. The simultaneous effects of corrosion and moisture at normal

temperature had not been taken into account. The established longevity was

not corrected after factoring in the actual degradation observed during

periodic surveillance of the individual seals.' Also, an administrative

mechanism was not in place to replace the seals before their estimated

qualified life expired. The original seal material in the Bunker-Ramo

electrical penetration assembly has polyesterurethane manufactured by Parker

Packing Company (Parker) under the trade name of Parkerthane (Parker Compound

No. P4611). Parker, which manufactures both polyester urethane and polyether

urethane seals, indicated in its catalog that polyester urethane maintains

critical characteristics up to 6 years while polyether urethane maintains

critical characteristics up to 10 years.

The polyester urethane (the originally installed seal material) was determined

inadequate for several reasons:

Short expected life (independently estimated at 2-5 years under some

conditions)

Incompatibility with water (hydrolysis shortens life)

Incompatibility with high temperature (acceleration of hydrolysis)

Susceptibility to compression-set (a slowly acquired permanent

deformation)

The licensee used different lubricants over the years. In 1987, the licensee

determined that three seals had failed because they were erroneously

lubricated with an incompatible (silicone) grease. After examination of seal

failures that occurred in 1991, Parker determined that the failed seals had

castor oil residue on the exterior, indicative of the use of Celvacene

lubricant', which'includes castor oil and cellulose acetate butyrate.

Celvacene, specified for use by the original penetration supplier, can cause

IN 93-25 April 1, 1993 degradation of polyurethane as follows. The cellulose acetate butyrate

component breaks down in the presence of moisture, producing butyric acid, which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowly

degrades the polyurethane material. Under accident conditions, the seal

degradation may be accelerated.

The original penetration supplier, Bunker-Ramo, no longer supplies such

assemblies. Similar electrical penetration assemblies have been supplied by

Amphenol, but this company also no longer supplies such assemblies.

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.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachment:

List of Receitly Issued NRC Information Notices

14 Attachment a

IN 93-25 4c

April 1, 1993 Page I of I

40L '0

LIST OF RECENTLY ISSUED

INFORMlATION NOTICES

KRC

I UJ :3 UflU U

Inrormation

Notice No. Subject Issuane Issued to

0

Distribution of 03/31/93 All holders of orater and A.

93-24 Revision 7 of PURE6-1021. senior operator eienses at

0Operator Licensing nuclear power reactors.

Examiner Standards"

93-23 Weschler Instruments 03/31/93 All holders of OLs or CPs

Nodel 252 Switchboard for nuclear power reactors.

Peters

93-22 Triping of Klockner- 03/26/93 All holders of OLs or CPs

Nfoeller Molded-Case for nuclear power reactors.

Circuit Breakers due to

Support Level Failure

93-21 Summary of NRC Staff 03/25/93 All holders of OLs or CPs

Observations Compiled for light water nuclear

during Engineering Audits power reactors.

or Inspections of Licen- see Erosion/Corrosion

Programs

I

03/24/93 All holders of OLs or CPs i

93-20 Thermal Fatigue Cracking

of Feedwater Piping to for PWRs supplied by

• Steam Generators Westinghouse or Combustion

Engineering.

93-19 Slab Hopper Bulging 03/17/92 All nuclear fuel cycle

licensees.

93-18 Portable Moisture-Density 03/10/93 All U.S. Nuclear Regulatory 2 Gauge User Responsibilities Commission licensees that

I(00

) during Field Operations possess moisture-density

gauges. 00

93-17 Safety Systems Response 03/08/93 All holders of OLs or CPs W O

to Loss of Coolant and for nuclear power reactors. 1c1 Loss of Offs1te Power

93-16 Failures of Nut-Locking 02/19/93 All holders of OLs or CPs

Devices in Check Valves for nuclear power reactors.

IL I

-IU

4):

zU

OL - Operating License n 2 Z a

FA.~

CP - Construction Permit

IN 93-25 April 1, 1993 degradation of polyurethane as follows. The cellulose acetate butyrate

component breaks down in the presence of moisture, producing butyric acid, which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowly

degrades the polyurethane material. Under accident conditions, the seal

degradation may be accelerated.

The original penetration supplier, Bunker-Ramo, no longer supplies such

assemblies. Similar electrical penetration assemblies have been supplied by

Amphenol, but this company also no longer supplies such assemblies.

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.

orig /s/'d by BKGrimes

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachment:

List of Recently Issued NRC Information Notices

• SEE PRMV a CONCURRENCES

• C/OGCB:DORS:NRR*RPB:ADM *D/DRIL:NRR *C/RVIB:DRIL:NRR

GHMarcus TechEd CERossi LJNorrholm

03/05/93 04/13/92 03/03/93 02/27/93

• OGCB: DORS:NRR *RESINSP/RV *RVIB:DRIL:NRR *SC/RVIB:DRIL:NRR

CVHodge RBarr KNaidu GCwallna

06/03/92 06/03/92 01/11/93 02/27/93 DOCUMENT NAME: 93-25.IN

IN 93-XX

March xx, 1993 castor oil residue on the exterior, indicative of the use of Celvacene

lubricant, which includes castor oil and cellulose acetate butyrate.

Celvacene, specified for use by the original penetration supplier, can cause

degradation of polyurethane as follows. The cellulose acetate butyrate

component breaks down in the presence of moisture, producing butyric acid, which in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowly

degrades the polyurethane material. Under accident conditions, the seal

degradation may be accelerated.

The original penetration supplier, Bunker-Ramo, no longer supplies such

assemblies. Si ilar electrical penetration assemblies have been supplied by

Amphenol6w-butThis company also no longer supplies such assemblies. -A

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.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachment:

List of Recently Issued NRC Information Notices

Document Name: PRESBOUN.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR

BKGrimes

03/ /93U

• C/OGCB:DORS:NRR*RPB:ADM *D/DRIL:NRR C/RVIB:DRIL:NRR

GHMarcus TechEd CERossi LJNorrholm

03/05/93 04/13/92 03/03/93 02/271/93

• OGCB:DORS:NRR *RESINSP/RV *RVIB:DRIL:NRR *SC/RVIB:DRIL:NRR

CVHodge RBarr KNaidu GCwalina

06/03/92 06/03/92 01/11/93 02/27/93

IN 93-XX

March xx, 1993 degradation of polyurethane as follows. Ihe cellulose acetate butyrate

ccuponent breaks dawm in the presence of irsture, producing butyric acid, whici in turn catalyses hydrolysis of the seal polymer. The hydrolysis slowly

degrades the polyurethane material. Mier accident cmditins,, the seal

degradation may be accelerated.

The original penetration supplier, Bunker-Ramo, is no longer in the business.

Similar electrical penetraticn assemblies have been splied-by Anphenol, but

this ccapany also is no lcnger in the hksiness. Ihe licensee at Trojan

replaced its Eunker-Ramo electrical penetration assemblies with Ckmax

electrical penetration assemblies.

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 aPqrcpriate Office of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Cperating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naid, NRR

(301) 504-2980

Attachment:

List of Recently Issued NR Information Notices

D x:mnt Name: PRESBCEXI IN

• SEE PREVIOUS aONCNRRENcS

D/DORS:NRR C/OGCB:DORS:MMR*RPB:ADM *D/MlUL:NfR

BI~rimes Grfrcus64W Tech~d CEossi

02/ /93 03/S /93 04/13/92 03/03/93

• OGCB:DORS:NRR *PMINSP/RV *REV :RI:NR:R *SC/RVIB:DR:M;R*C/RIB:WIL:NRR

CvHodge RBarr .Naidu GwalinamJ~orrhobii

06/03/92 06/03/92 01/11/93 02/27/93 02/27/93

- IN 93-XX

February xx, 1993 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.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachment:

List of Recently Issued NRC Information Notices

Document Name: PRESBOUN.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR C/OGCB:DORS:NRR*RPB:ADM

BKGrimes GHMarcus TechEd

02/ /93 02/ /93 04/13/92

• OGCB:DORS:NRR *RESINSP/RV *RVIB:DRIL:NRR SC/RVIB:DRIL:NRR CYRU:DRIL:NRR

CVHodge RBarr KNaidu GCwalina LJNorrholm

06/03/92 06/03/92 01/11/93 02/ /93 02/ /93

IN 93-XX

January xx, 1993 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.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachment:

List of Recently Issued NRC Information Notices

Document Name: PRESBOUN.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR C/OGCB:DORS:NRR*RPB:ADM D/DRIL:NRR C--#-

BKGrimes GHMarcus TechEd CERossi

01/ /93 01/ /93 04/13/92

• OGCB: DORS:NRFZ *RESINSP/RV *RVIB:DRIL:NRR IB:DRIL:NRR 01/jg gmlL:NRR

/93 CVHodge RBarr KNaidu Gaina

06/03/92 06/03/92 01/11/93 /93 DD:DRIL:NRR

RZimmerman

01/ /93

. ,

IN 93-XX

January , 1993 under loss of coolant accident (LOCA) conditions. Premature degradation of

the insulation covering the electrical connections can expose the connections

to an adverse environment during a LOCA. A brief survey of these LERs is

included in Attachment 1.

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 Off ce of

Nuclear Reactor Regulation (NRR) project manager.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regu lation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachments:

1. Survey of Licensee Event Reports (LERs)

2. List of Recently Issued NRC Information Notices

Document Name: PRESBOUN.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR C/OGCB:DORS:NRR*RPB:ADM

BKGrimes GHMarcus TechEd

01/f /93 01/ /93 04/13/92

• OGCB:DORSONRR *RESINSP/RV ! n IB:DRIL:NRR C/RVIB:DRIL:NRR D/DRIL:NRR

CVHodge USA RBarr KNai du LJNorrholm CERossi

06/03/92 0413 06/03/92 01/11/93 01/ /93 01/ /93

. .I zi' k I '. ,

. - : I , :

K> IN 93-XX

January xx, 1993 identify excessive leakage of EPA seals indicating possible degradation from

moisture intrusion. Degraded seals can cause breach of containment integrity

under loss of coolant accident (LOCA) conditions. Premature degradation of

the insulation covering the electrical connections can expose the connections

to an adverse environment during a LOCA. A brief survey of these LERs is

included in Attachment 1.

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.

Brian K. Grimes, Director

Division of Operating Reactor Support

Office of Nuclear Reactor Regulation

Technical contacts: C. Vernon Hodge, NRR

(301) 504-1861 Robert C. Barr, Region V

(509) 377-2627 Kamal Naidu, NRR

(301) 504-2980

Attachments:

1. Survey of Licensee Event Reports (LERs)

2. List of Recently Issued NRC Information Notices

Document Name: PRESBOUN.IN

• SEE PREVIOUS CONCURRENCES

D/DORS:NRR C/OGCB:DORS:NRR*RPB:ADM D/DRIL:NRR

BKGrimes GHMarcus TechEd CERossi

01/ /93 01/ /93 04/13/92 01/ /93 OGCB:DORS:NRR RESINSP/RV *RVIB:DRIL:NRR SC/RVIB:DRIL:NRR C/RVIB:DRIL:NRR

CVHodge V@ RBarr w KNaidu GCwalina LJNorrholm

06/o3/92 01/11/93 01/ /93 01/ /93

01 /Iq/3

of EPA seals represent violations of Containment integrity and environmental

qualification deficiencies in EPA components indicatepe s m - /~u4n-deiiP

coddia")

loss~bf(oolant accident (LOCA) co'nditions. A brief survey of these LERs I4B'

in .ttachmet Cincluded

A im

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: Vern Hodge, NRR

(301) 504-1861 Rob Barr, RV

(503) 556-3751 Attachments:

1. Survey of Licensee Event Reports (LERs)

2. List of Recently Issued NRC Information Notices

Document Name: BUNK0403 REV 19 D/DOEA:NRR C/OGCB:DOEA:NRR

CERossi CHBerlinger

04/ /92 04/ /92 OGCB:DOEA:NRR RESINSP/RV ROAB:DSP:NRR RVIB:DRIS:NRR RPB:ADM

CVHodge RBarr SMazumdar KNaidu TechEd J'Ma;, )

04/ /92 04/ /92 04/ /92 04/ /92 04/13 /92