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, 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, 05000000, Zimmer, Fort Saint Vrain, Shoreham, Satsop, Trojan, Atlantic Nuclear Power Plant, Skagit, Marble Hill
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, ammoonia 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.

Dooo 7

IN 87-16 April 2, 1987 Discussion:

in their Class 1E

SOR generally uses Kapton as the primary diaphragm materialthe environmentally

qualified switches. Toledo Edison had recently installed

commercial grade

qualified switches as part of a system upgrade. Earlier model In 1979, the

SOR pressure switches at Davis-Besse used BUNA-N diaphragms.

diaphragms. Because

BUNA-N diaphragms were replaced with 316 stainless steel switches using stainless

there have been no reported malfunctions of pressure

steel is impermeable to ammonia, the

steel diaphragms and because stainless pressure switches

pressure switches using Kapton diaphragms were replaced with

using stainless steel diaphragms.

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

during normal operation

conditions that the switches would be subjected to to perform its required

were not specified. Thus, the ability of the switch

because the procurement

function In response to an accident was degraded

documents did not specify the normal process medium.

a considerable period of

The instrument drift condition can go undetected foroperability during bimonthly

time. At Davis-Besse, the switches are tested foris verified during each refuel- surveillances The calibration of the set point

Ing outage. Th refore, even though the switch may not demonstrate operability, be detected until

setpoint drift exceeding the specified limits may

refueling outage calibrations.

Davis-Besse Is that the

Another factor contributing to the Instrument drift atthe lower end of the

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

condition caused by the

adjustable range (10-85 psg). The Instrument drift layers may not be

w

formation of an ammonia bubble between the diaphragm

significant on switches used In high pressure applications.

t

of Kapton, that

Additionally, NRC has learned from DuPont, the manufacturer

hydroxide, sodium hydro- certain concentrations of chemicals such as ammonium degrade. When determining

xide, and potassium hydroxide will cause Kapton to Kapton diaphragm to a parti- the suitability of an SOR pressure switch using a the resistance of Kapton to

s cular application, it may be desirable to examine For further information on

chemicals present in the application environment.

4 Kapton properties call:

i

DuPont Company

I

Electronics Department

i

High Performance Films Division

1-800-527-2601 I

I

i

i

z

q

IN 87-16 April 2, 1987 this notice. If you have any

No specific or written tesponse is required by the Regional Administrator of

questions regarding this matter, please contact

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:

List of Recently Issued IE Information Notices

Attachment 1

1i 87-16 April 2. 198?

LIST OF RECERTLY ISSUED

IE IXFO0IATION N10lCES

Inror4ation DAte or

Notice Iso. sublect Issue issued to

t7-15 Coeplaince with the Posting 3/251/B All power reactor

Requirements et sbsection facilities holding

223b of the Atomic Energy a CP and 811 firms

Act of 1954. as Amended supplying Components

or services to such

facilities

Actuation of Fire Sup, 3/23/27 All power reactor

S714 pressien System Causing facilities holding

Inoperability of Safety- an OL or Ct

Related ventilation Equipment

66-106 Sup. 2 Foedwater Line Break 3/18/81 All power reactor

facilities holding

an OL or CP

potentiel tor High Radiation 2/24/87 All power MK;Ar

S.-13 facilities holding

fields following Less at

Water from Fuel Pool an OL or CP escept

Fort St. VraIn.

Feedwater tine Break 2/13/87 All power reactor

86 106 SuP I

facilities holding

an 0L or CP

2/13/8? All power reactor

S8-12 Potential Problees With

Ketal Clad Circuit Breakers, facilities holding

General Electric lype AKF-2-25 an OL or CA

87-11 Enclosure of Vital Equipment 2/13/t7 All power reactor

within Designated SMtal facilities holding

Areas an O or CP

Potential for Water Hawer 2/11/Si All BWR facilities

S1-10 holding an OL or CP

During Restart of Residual

Heat ReoWal Pumps

Emergency Diesel Generator 2/5/I? All pwr reactor

81-09 facilities holding

Room cooling Design

Deficiency an OL or CP

Degraded Motor teads In 2/4/li All power reactor

54.08 Limitoroue COMotor facilities holding

Operators an OL or CP

OL

• Oporating license

Ct

• ConstructIon Permit

UNITED STATES FIRST CLSASS IL1 NUCLEAR REGULATORY COMMISSION I PTA09 b M1St PAID

WASHINGTON, D.C. 2M55 4 WASH CC4 OFFICIAL BUSINESS

PENALTY FOR PRIVATE USE *300