ML20236P395

Forwards Addl Info Re Adequacy of Reactor Trip Breaker Life Testing,As Documented in Westinghouse WCAP-10835,per NRC 870908 Request for Addl Info Re Generic Ltr 83-28,Item 4.2 (Parts 3 & 4)

ML20236P395
Person / Time
Site:	Callaway
Issue date:	11/13/1987
From:	Schnell D UNION ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
GL-83-28, ULNRC-1678, NUDOCS 8711170286
Download: ML20236P395 (5)

Text

7-1 u G % Ugog n 1  ;

Et..scraic:  ;

1901 Gratiot Street. St.' Louis Donald F. Schnell; Vice President :

i November 13, 1987

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U.'S.' Nuclear, Regulatory Commission ATTN: 6 Document: Control Desk-Washington,.D.C. 20555 o a

Gentlemen:. ULNRC-1678-DOCKET.. NUMBER 50-483 CALLAWAY PLANT-

.NRC GENERIC LETTER 83-28

Reference:

NRC Request'for' Additional Information Regarding Generic Letter-83-28,-Item'4.2 j

(Parts 3 and 4), T. W. Alexion (NRC) to

-D. F.iSchnell (UE) dated 9/8/87- '

The referenced. letter requested additional information  !

1p ,1regarding the' adequacy of reactor trip breaker life testing, as

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.. documented by Westinghouse in their topical report WCAP-10835.

Based on the discussions in the attachment, Union Electric _ _ ,

maintains lthat the requirements of Generic ~ Letter 83-28, Item 4.2 (Parts 3 and-4)'have been satisfied for Callaway Plant. If you

.have any questions on the-attachment, please-contact us.

Very-truly yours, Donald F. Schnell-GGY/kea

' Attachment

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Q1170286 871113 p ADOCK 05000483 PDR fh

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' Maihng Address: P,0. Box 149, St. Louis, MO 63166

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i DonaldiF. Schnell, o'f'lawfulLage,'being first duly sworn- .i

<upon oath says that ..he is -'Vice- President-Nuclear and an officer of- .

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L  : Union Electrici Company; that1h'e has. raad the.; foregoing documenti and -]

knows the,. content ^ thereof;.Lthat helhas Lexecuted . the same for and : ons aj

behalf ' of said..-company : with f ull . pbwer and:. authority ' to. do so; arid ,

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.that? the ifacts thereinf stated are true and correct' to" the best of his-

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..knowledg e , J.information Fand : belief.

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i By- l l? Donald F. Schnells +!

.Vice. President' i Nuclear ,i 1

? SUBSCRIBED and ' sworn to .before mef this. /M day of /2444m/2</, 1987 1

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DARGARA J. PFA F (/ f

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1b NOTARY PUBUC, STATE OF MISSOURI

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.l MY COMMISSION EXPIRES APRIL 22, 1989 -

4 ST. LOUIS COUNTY.

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,.cc : Gerald'Charnoff, Esq.

Shaw -Pittman-2300,N.-

Streeb,,;Potts N.W. & Trowbridge

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Washington, D.C.- 20037;

-r D r, ^. J.:.O. Cermak-C F A ,.f I n c . ..f .

, 4 Professional-Drive (Suite :110)-

,,3 Gaithe rsburg,- MD 20879..

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W ey W. L. .. Forney:t

, yChief,: Reactor Project Branch.1 U.S. Nuclear RegulatoryfCommission

' RegionLIII

. 799 Roosevelt Road . ,

' Glen Ellyn, Illinois;60137 Bruce.Little .

Callaway': Resident 'Of fice

U.S.KNucleariRegulatory Commission RRil Steedman,' Missouri 65077 1

- Tom s Alexion D-(2):

Officeiof(NuclearJReactor Regulation U.S. Nuclear? Regulatory. Commission

' Mail. Stop 1316 ,

.7920' Norfolk Avenue  !

Bethesda, MD. 20014.

-i Mana'g e r , :- Elec tric Depar tment Missouri Public Service Commission P.O.: Box 360 Jefferson City, MO 65102 I

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ULERC-1678 i Novend)er .13, 1987  ;

-Qualification ofL he t DS-416 reactor trip breakers was conducted'

by Westinghouse with consideration given to'all significant mechanisms-of degradation which could affect the functional capability-of the

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-breakers. . Thermal aging is not a requirement-for this qualification program, as discussed hereinafter.

.The breakers, which contain primarily metallic and the non-metallic' materials, have been evaluated by analysis in the Westinghouse topical report " Equipment Qualification Test Report Materials Aging Analysis," WCAP-8687, Supplement 2, Appendix A2  ;

(Proprietary). Arrhenius plots for the non-metallic materials demonstrate acceptable ' performance af ter 40 years at 50*C, As documented in.WCAP-8587, " Methodology for' Qualifying Westinghouse WRD Supplied NSSS Safety-Related Electrical Equipment," Revision 6-A,-

reactor trip,switchgear does not experience pronounced property

. degradation.due to thermal aging. Therefore, seismic testing on-unaged switchgear is not prejudiced by any inservice thermal' aging mechanisms. WCAP-8587 was approved.by NRC on 11/10/83.

As documented in FSAR Section 3.11(B).5.7, qualidied life expectancy is not. established for equipment located la mild environments. 'This is consistent with Generic Letter 82-09 and the Statements of Consideration. supporting 10CFR50.49 (48FR2729). The s reactor trip breakers are subject to extensive QA, maintenance, and surveillance programs which, per the above references, are sufficient for demonstrating their qualification in a mild environment application. In addition, parameters affecting operation of the reactor trip,switchgear, such as undervoltage trip attachment (UVTA) drop-out voltage, UVTA trip force and breaker load, and breaker

. response time, are included in our trending program and degradation of operability would.be detected. (ref. ULNRC-1002 dated 12/27/84).

In the licensing review of seismic and dynamic qualification of equipment for the SNUPPS plants, the NRC review team also indicated that an adequate surveillance and maintenance program was sufficient for monitoring age-related degradation of mild environment equipment.

IEEE Standard 323 was revised in 1983 to provide specific guidance for qualification of mild environment equipment.

IEEE-323-1983 states that qualified lives are not required for equipment located in' mild environments and which have no significant aging mechanisms. IEEE Standard 323-1983 also states that, with

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t regard to seismic testing of equipment located in mild environments, I pre-aging prior to seismic tests is required only where significant aging mechanisms exist.

Therefore, the requirement to establish qualification using IEEE-323-1974 goes beyond current regulatory guidelines for mild )

environment equipment. In recognition of this fact, the discussion of I compliance with Regulatory Guide 1.89 in Callaway FSAR Section 3A )

takes exception to the recommendations of this regulatory guide with regard to equipment in mild environment applications.

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.fWyle Labs has" tested'several electrical dhvices to assess the-m >

-extent of any' correlation between aging and seismic' qualification for.

.' electrical.. equipment, including several switchgear-components.such as.

Eterminal: blocks,. fuse blocks,. relays, and circuit boards (reported'in-

.EPRI:NP-3326 and EPRI NP-5024). The general conclusion from this test-iprogram is that, except.for certain switches, accelerate'd aging (thermal, radiation, and cycling) did not degrade seismic performance

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an' aging-seismic correlation was' observed'are not used in_ reactor trip ~

switchgear'at Callaway (no rotary, limit, or pressure switches).

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original. testing on reactor. trip switchgear with DS-416 breakers 5(Westinghouse EQDP.ESE-20)~did not include'the performance of thermaljaging, based 'onYthe materials analysis discussed 'above. This test program included 1000' operations prior to seismic testing. After being upgraded;to Class 1E, the shunt trip' attachments were qualified

.in'a program that included-thermal and' mechanical' aging prior to seismic resting-(Westinghouse EQTR E62A, Addendum 1, Proprietary)'.

The shunt. trip attachments l(STAS) werelaged for 5510. hours at 1105'C.

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Using an activation' energy ^of 0.65 eV, which io conservatively high 3

for STA non-metallic materials, this equates to 40-years at 40*C (40'C.'

lis the design maximum ambient temperature for the reactor trip g switchgear).

-Given;the above, it isiour position that the DS-416 breakers and trip attachments are not affected by thermal aging and are, therefore, limit'ed only by mechanical-(cyclic) life considerations.' The cyclic s , life testing = documented in WCAP-10835, " Report of the DS-416 Reactor Trip., Breaker Undervoltage and Shunt Trip Attachments Life Cycle

' Tests," demonstrated l acceptable performance'of both' trip attachments N and breakers after.2500 operations. Two breakers experienced over 10,000 operations. Our conservatively.high estimate of 1,650.'

operations.over 40 years is based on'two (2): cycles every 62' days for l

monthly surveillance per Technical Specification Table 4.3-1, 11 cycles'every refueling outage during breaker maintenance, and 840 cycles per FSAR Table 3.9(N)-1 which include reactor trips during

r. . upset, emergency, and faulted conditions. Only the trip attachments i contain non-metallic materials critical to the breaker's safety pl l function., Both the UVTA and STA have'cycli_c life restrictions of 1,~250 operations at Callaway which is one-half of that demonstrated in WCAP-10835.

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