Information Notice 1987-16, Degradation of Static O Ring Pressure Switches

Degradation of Static O Ring Pressure Switches

ML031180005
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, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill, Crane
Issue date:	04/02/1987
From:	Jordan E NRC/IE
To:
References
IN-87-016, NUDOCS 8703310090
Download: ML031180005 (4)

SSINS No.:

6835 IN 87-16

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555

April 2, 1987

IE INFORMATION NOTICE NO. 67-16:

DEGRADATION OF STATIC "O" RING PRESSURE

SWITCHES

Addressees

All light-water reactor facilities holding an operating license or a

construction permit.

Purpose

This notice is to alert addressees to the potential for degradation of certain

Static "0" Ring (SOR) pressure switches with Kapton diaphrags caused by

exposure to ammonia and other chemicals that may be present in the process

medium. It Is expected that recipients will review the Information for appli- cability 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 Circumstencs:

A number of SOR pressure switches (Model No. 6TA-64-NX-JJTTX6) were declared

inoperable at the Davis4-esse Nuclear Power Plant between January 7 and 12,

1987, when results of a routine surveillance indicated that the pressure switch

set points had drifted outside of technical specification tolerances. The SOR

switches that were declared inoperable, are located on the lines supplying

steam to the auxiliary feedwaLer (AFW) pump turbines and Are used to detect a

low steam pressure and Isolate the affected AFW pump in the event of a steam

line break.

Subsequent Investigation by the licensea, Toledo Edison, and SOR revealed that

ammonia present in the steam lines had interacted with the Kapton diaphragm of

the pressure switch, permeated it, and formed A bubble between the laminations

of the Kapton diaphragm (fluorinated silicone membrane). It is believed that

the formation of this bubble between the diaphragm layers caused the set point

of the switch to shift.

At Davis-Besse, a

mmoonia is added to the feedwater system to help control

chemistry primarily pH. Hydrazine, which is regularly added to coolant

systems to help control chemistry and to scavenge oxygen, also is a source of

ammonia because hydrazine reacts with oxygen to form ammonia.

SOR has stated

that qualified pressure switch models beginning with 1, 4, 5, 6, S, 9, 12, and

54 may be affected if ammonia Is present in the process medium.

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IN 87-16 April 2, 1987 Discussion:

SOR generally uses Kapton as the primary diaphragm material in their Class 1E

qualified switches. Toledo Edison had recently installed the environmentally

qualified switches as part of a system upgrade. Earlier model commercial grade

SOR pressure switches at Davis-Besse used BUNA-N diaphragms. In 1979, the

BUNA-N diaphragms were replaced with 316 stainless steel diaphragms. Because

there have been no reported malfunctions of pressure switches using stainless

steel diaphragms and because stainless steel is impermeable to ammonia, the

pressure switches using Kapton diaphragms were replaced with pressure switches

using stainless steel diaphragms.

When Toledo Edison ordered the Class 1E switches from SOR, the environmental

conditions that the switches would be subjected to during normal operation

were not specified. Thus, the ability of the switch to perform its required

function In response to an accident was degraded because the procurement

documents did not specify the normal process medium.

The instrument drift condition can go undetected for a considerable period of

time. At Davis-Besse, the switches are tested for operability during bimonthly

surveillances

The calibration of the set point is verified during each refuel- Ing outage. Th refore, even though the switch may demonstrate operability, setpoint drift exceeding the specified limits may not be detected until

refueling outage calibrations.

Another factor contributing to the Instrument drift at Davis-Besse Is that the

set point for the pressure switches (20 psig) was on the lower end of the

adjustable range (10-85 psg). The Instrument drift condition caused by the

formation of an ammonia bubble between the diaphragm layers may not be

significant on switches used In high pressure applications.

Additionally, NRC has learned from DuPont, the manufacturer of Kapton, that

certain concentrations of chemicals such as ammonium hydroxide, sodium hydro- xide, and potassium hydroxide will cause Kapton to degrade. When determining

the suitability of an SOR pressure switch using a Kapton diaphragm to a parti- cular application, it may be desirable to examine the resistance of Kapton to

chemicals present in the application environment. For further information on

Kapton properties call:

DuPont Company

Electronics Department

High Performance Films Division

1-800-527-2601

IN 87-16 April 2, 1987 No specific or written tesponse is required by this notice.

If you have any

questions regarding this matter, please contact the Regional Administrator of

the appropriate regional office or this office.

A

rector

Divis10 of Emergency Preparedness

and Engineering Response

Office of Inspection and Enforcement

Technical Contact(s): K. R. Naidu, IE

(301) 492-4179

J. G. GWitter, IE

(301) 492-4043 Attachment:

Attachment 1

1i 87-16 April 2. 198?

LIST OF RECERTLY ISSUED

IE IXFO0IATION N10lCES

Inror4ation

DAte or

Notice Iso. sublect

Issue

t7-15 Coeplaince with the Posting

3/251/B

Requirements et sbsection

223b of the Atomic Energy

Act of 1954. as Amended

S714 Actuation of Fire Sup,

3/23/27 pressien System Causing

Inoperability of Safety-

Related ventilation Equipment

66-106 Sup. 2 Foedwater Line Break

3/18/81 S.-13 potentiel tor High Radiation 2/24/87 fields following Less at

Water from Fuel Pool

86 106 SuP

I

Feedwater tine Break

2/13/87 S8-12 Potential Problees With

2/13/8?

Ketal Clad Circuit Breakers, General Electric lype AKF-2-25

87-11 Enclosure of Vital Equipment 2/13/t7 within Designated SMtal

Areas

S1-10

Potential for Water Hawer

2/11/Si

During Restart of Residual

Heat ReoWal Pumps

81-09 Emergency Diesel Generator

2/5/I?

Room cooling Design

Deficiency

54.08 Degraded Motor teads In

2/4/li

Limitoroue CO Motor

Operators

OL

• Oporating license

Ct

• ConstructIon Permit

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 2M55

OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE *300

issued to

All power reactor

facilities holding

a CP and 811 firms

supplying Components

or services to such

facilities

All power reactor

facilities holding

an OL or Ct

All power reactor

facilities holding

an OL or CP

All power

MK; Ar

facilities holding

an OL or CP escept

Fort St. VraIn.

All power reactor

facilities holding

an 0L or CP

All power reactor

facilities holding

an OL or CA

All power reactor

facilities holding

an O or CP

All BWR facilities

holding an OL or CP

All pwr reactor

facilities holding

an OL or CP

All power reactor

facilities holding

an OL or CP

FIRST CLSASS IL1

I PTA09 b M1St PAID

4 WASH CC4