ML20050C862

Estimation of Svc Life of EA170-XX302 Limit Switches for Class IE Use,Outside of Containment Area of Nuclear Power Plants.

ML20050C862
Person / Time
Site:	Sequoyah
Issue date:	11/09/1979
From:	NAMCO
To:
Shared Package
ML20050C841	List: ML20050C840 ML20050C856 ML20050C859 ML20050C862 ML20050C863 ML20050C873 ML20050C881 ML20050C884 ML20050C891 ML20050C896 ML20050C927 ML20050C958 ML20050C961 ML20050C962 ML20050C963 ML20050C964 ML20050C965 ML20050C971 ML20050C975 ML20050C982 ML20050C988 ML20050C999 ML20050D000 ML20050D003 ML20050D008 ML20050D009 ML20050D011 ML20050D013
References
RTR-NUREG-0588, RTR-NUREG-588 IEB-79-01B, IEB-79-1B, NUDOCS 8204090419
Download: ML20050C862 (3)

Text

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- November 9, 1979 Estimation Of Service Life -

l Of EA170-XX302 Limit Switches #

For Class IE Use, Outside of The .

k Containment Area Of tJuclear Power Plants ,

Quali fication Report Dated 3/17/78 f, 7/24/78 -

Switch P/!Jo. E Al;/0-l l302 Rev. E Through G.

The purpose of this presentation is to show that the service life of the EA170 series limit switch exceeds 20 years, under normal service conditions.

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The !!amco Controls' Quali fication Test Procedure included -

three types of aging; thermal ag i n'g, mech an i ca l aging and rad-

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iation aging. ,

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As a result of an Engineering study the components of the switch were classified into three groups: el as tome ri c seal s ,

other non'-metallic components and metallic co~mponents.

The metallic components, such as, zinc alloy housings, steel-al~loy covers, steel aTloy shafts and fasteners are not affected by the thermal condi tions of ' service or test.

iJon-metallic comoonents; the contact carriers and blocks are made from thermoset plastics-which has been supplied, by

c. our vendor, to the industry for over fi f tcen years. T,his U thermoset plastic is listed by UL with-an index of 130 C, the average endurance time being 100,000' hou r s (12 years) for this temperature. Ext rapol at ion of the' leg res srion curv.e p rovi des an estimated li fe of greater than 50 years. The l ub r i can t man-ufacturer was unable to provide thcrmal aging characteristics for the synthetic lub ricants used, E-zever; our experience in-dicates the proper application of the proper amount is more critical than the thermal aging charactefistics of the lubri-cant. ~

Relubrication of the switch on a ffve year cycle would . ' '

extend the li fe of the swi tch beyond-t he 20 year estimate.

Elastomeric seals, the cover hasket material is a methyl

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vinyl ~(VIiQ) type Ti 1Tcone cubber,- generic aging i n forma t i on

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for this type of material i_nnicates t. hat minimal physical ,

changes occu r a f ter exposure _.to inmpe rat urer of .150 C (320 F) for less than one year (1) (2). CatalogJdata from the two leading manufacturers of s i l icone ,rubbe r s tates a se rv i ce 11fe of from 10 to 20 years at 150 C and when conservatively p roj e,c t ed indicates a service li fc of greater than 90 years at-90 C (3).

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8204090419 820407 p DR ADOCK 05000327 PDR

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Y November 9, 1979 The shaft seal is a viton o' ring, generic aging i n forma-tion on this type of material indicates,that no change in

, durometer occurs af ter 11 months at 148 C and other physical ks cha rac t e ri s t i c's act ual l y imp roved (the o' ring is considered as a static seal). Indefinite service life is obtained under these conditions (4),

The EA170-XXJ02 series swi tches have a maximum rated temperature of 90 C.- Service temperatures for outside the c op t ai nmen,t area (as proposed in IEEE 382 Draft's) range fr6m 40 C to 60 C. .

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It is impractical to thermally age the switch' assembly at a high enough temperature or long enough duration of time to cause a signi ficant change in the three groups of materials and sti,ll simulate the long service life at low temperature without causing unusual outgassing and physical changes.

Therefore, the switch was heat soaked at 200 F for 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> to stabilize all the components.

The data search also disclosed that the radiation thres-hold of damage for.viton and si1icone rubber is as 1ow as 1 X 10' Rads for some compounds (1) (4). The radiation aging, of the quali fication test p rocedu re , is 20.4 X 107 Rads. &

The re fo re , it can be concluded that the cl as tome ric seal s

/l were at or beyond the condi tion of "end of li fe", as required

'd by IEEE 323 (5). Before the swi tch was subj ected to seismic conditions. [

Based upon the above data we can consider the es timated se rvi ce li fe of the EA170-XX302 series switches to be approx-imately 20 years, assuming the contacts are cleaned every two years and relubrication is carried out eve ry five years.

References:

(1) General E 1 ect ric Company Technical Data Book S-lE Silicone Rubber Technical I n fo rma t i on (2) Dow Corning Corporation Designing wi th Silastic Silicone Rubber -

Bulletin 17-158, Date: 10/72 (3) E. I. DuPont De tJemours & Co. (inc.)

El ast ome r Chemical Departmen t Wilmington, Oclaware

- Upgrading Seal Performance with DuPont Viton Cat alog A98591 S

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- - - - November 9, 1979 (4) E. 1. DuPont De Nemour.s & Co. (inc.) ,

- Elastomer Chemical Department .

l Wilmington, Delaware j The Engineering Properties of _Viton _ ~

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Catalog A65D53, 4/69 ,

I (5) IEEE 323-1974, section 6.3.3 Aging .

Std. For Quali fying Class IE Equipment for .

- Nuclear Power Generating Stations .

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