ML20248B499

Forwards Util Response to Item 4.2 (Parts 3 & 4) of Generic Ltr 83-28 Re Preventive Maint & Surveillance Program for Ensuring Reliable Reactor Trip Breaker Operation

ML20248B499
Person / Time
Site:	Comanche Peak
Issue date:	06/07/1989
From:	Joshua Wilson Office of Nuclear Reactor Regulation
To:	Rosa F Office of Nuclear Reactor Regulation
References
GL-83-28, TAC-R00402, TAC-R402, NUDOCS 8906090080
Download: ML20248B499 (2)

Text

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h. June 7, 1989 Docket Nos. 50-445 and 50-446 MEMORANDUM FOR: Faust Rosa, Chief Electrical Systems Branch Division of Engineering & Systems Technology Office of Nuclear Reactor Regulation

SUBJECT:

RESPONSE TO ITEM 4.2 (PARTS 3 AND 4) 0F GENERIC LETTER 83-28 FOR THE COMANCHE PEAK STEAM ELECTRIC STATION (TAC NO. R00402)

Reference:

Memorandum From F. Rosa to C. Grimes, " Request For Additional Information Item 4.2 (Parts 3 and 4) of Generic Letter 83-28 Comanche Peak Steam Electric Station (SRP Sections 7.2 and 17.2)", Dated August 26, 1987 Attached is TV Electric's response to your Request for Additional Infor-mation (Reference) regarding their preventive maintenance and surveillance programs for ensuring reliable reactor trip breaker operation. Please review TU Electric's rationale for not committing to perform the recom-mended life testing and/or an ongoing qualification program and provide us with an SER for inclusion in our next SSER.

If you have any questions for the applicant or would like to have a meeting to discuss the issues, please contact Mel Fields at x20765.

/s/

James H. Wilson, Assistant Director Comanche Peak Project Division Office of Nuclear Reactor Regulation j cc: A. Toalston F. Ashe

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/[ June 7, 1989 Docket Nos. 50-445 and 50-446 MEMORANDUM FOR: Faust Rosa, Chief Electrical Systems Branch Division of Engineering & Systems Technology Office of Nuclear Reactor Regulation

SUBJECT:

RESPONSE TO ITEM 4.2 (PARTS 3 AND 4) 0F GENERIC LETTEP. 83-28 FOR THE COMANCHE PEAK STEAM ELECTRIC STATION (TAC NO. R00402)

Reference:

Memorandum From F. Rosa to C. Grimes, " Request For Additional Information Item 4.2 (Parts'3 and 4) of Generic Letter 83-28 Comanche Peak Steam Electric Station (SRPSections7.2and17.2)", Dated August 26, 1987 Attached is TU Electric's response to your Request for Additional Infor-  !

mation (Reference) regarding their preventive maintenance and surveillance i programs for ensuring reliable reactor trip breaker operation. Please review TU Electric's rationale for not conanitting to perform the recom-mended life testing and/or an ongoing qualification program and provide us with an SER for inclusion in our next SSER.

If you have any questions for the applicant or would like to have a meeting to discuss the issues, please contact Mel Fields at x20765.

kh bw H. Wilson, Assistant Director Jam)st Coniatiche Peak Project Division J Office of Nuclear Reactor Regulation cc: A. Toalston F. Ashe i

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Log # TXX-89287 File # 10035

= r GL 83-28 1UELECTRIC " # **'"'***"

May 31, 1989 William J. Cahill. Jr.

Earcurwe Vect Presulent U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555

SUBJECT:

COMANCHE PEAK STEAM ELECTRIC STATION (CPSES) .

DOCKET NOS 50-445 AND 50-446 UPDATE OF GENERIC LETTER 83 REACTOR TRIP BREAKERS REF: 1. Generi Letter 83-28, " Required Actions Based on Generic Implications of Salem ATWS Events," dated July 8, 1983

2. Letter from C. I. Grimes to W. G. Counsil, " Request for 4 Additional Information Generic Letter 83-28 Item 4.2 Parts 3 dnd 4," dated September 2, 1987 Gentlemen:

Attached is the TU Electric response to Generic Letter 83-28 items 4.2 3 and 4.2.4.

Sincerely, 4

/ //

William 4 ahill, Jr.

VPC/ddm Attachment l c - Mr. R. D. Martin, Region IV Resident Inspectors, CPSES (3) l 76667/ G3 i

400 North Olive Street LB 81 Dalla, Tezu 75201 Q____-_-_____-

I Attachment to TXX-89287

.. ,. May.31, 1989-

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Pago 1-of 3-In Reference (1). Items;4.2.3 and 4.2.'4, the NRC' requested licensees and applicants to describe their preventive maintenance and surveillance programs for. ensuring reliable reactor trip breaker-(RTB) operation regarding:

(a)

• Life testing-of the' breakers -(including trip attachments)'on an acceptable sample size."

(b) " Periodic replacement of breakers or components' consistent with' demonstrated life cycles.*

In response to this request, TU Electric- submitted TXX-4071, dated November 3, 1983 ' indicating that'the Westinghouse Owners' Group was sponsoring a Westinghouse RTB life. cycle testing program on DS-416 breakers, which are installed at CPSES. The.results of this program were issued in Westinghouse topical report, WCAP-10835, " Report of the DS-416 Reactor Trip Breaker Undervoltage and Shunt Trip Attachments Life Cycle Tests." However, NRC review-of WCAP-10835 determined that the report:

-(1) Only addressed cyclic testing of the trip attachments, and (2)-Did_not address life qualification of RTB*s nor aging for the trip..

attachments. e I' Consequently, the NRC determined that WCAP-10835 did not address the concerns of the generic letter and therefore was unacceptable.

In Reference (2), the NRC requested the following additional information L regarding Items-4.2.3 and 4.2.4 of the generic letter.

• 1. The staff requested.TU Electric to qualify Comanche Peak breakers by (1) actual life testing of the breakers, including aging, on en l

acceptable sample size or (2) establishing an ongoing life testing program. If the first alternative is selected, present the results of

.the life testing to the staff for review. If the second alternative is selected, describe their ongoing life testing program."

• 2. The staff requested TU Electric to provide a replacement program for the breaker and breaker components based on the results of their life qualification program. For ongoing qualification, describe how the ongoing qualification results will be used to establish replacement cycles and times."

It is the opinion of TU Electric that Items 1 and 2, above, are unnecessary as described below. .

The CPSES reactor trip breakers are in a mild environment and are not expected to be exposed to an environment exceeding their design / purchase specifications environmental limits. In addition. TU Electric's maintenance / surveillance programs in conjunction with its preventive maintenance programs are adequate to ensure that the breakers will continue to meet their design / purchase specifications.

This is consistent with the Standard Review Plan (NUREG-0800)

Section 3.11 discussion of qualification of equipment located in a mild environment.

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' Attachment to TXX-892871

. ..c , May 31, 1989

• • ~ Page 2 of 3-TV Electric is committed to IEEE 323-1974 for qualifying Class 1E' equipment-.

Qualification of equipment located in a mild environment'is outside the scope of this' document. However, ir, 1983 IEEE 323 was revised. This revision L provided additional interrition regarding mild environments. The IEEE 323-1983 recommendations for addressing the effects of aging is as

follows

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i "For' equipment located in mijd environments and which has no significant aging mechanisms, a qualified life is not required. This equipment shall' be selected for application to the specific service conditions based on sound engineering practices and manufacturer's recommendations. With regard to seismic testing of equipment located in mild environments, preaging prior to seismic tests is required only where significant aging mechanisms exist."

The CPSES RTB switchgear is' located in an area'that will not see a harsh environment, as defined in the CPSES FSAR Section 3.11B. The worst case postulated environment during normal or accident conditions in the RTB switchgear area is 1040F, less than 80% relative humidity, atmospheric-pressure and a total integrated radiation dose less than 10E4 rads (4.3E3).

Since the worst case temperature and humidity values do not exceed the desjgn values and since studies show that for radiation values less than 10E4 no*,

deterioration in material structural properties is detectable.

Therefore,e the primary aging mechanism is due to mechanical operation. ~The postulated number of CPSES RTB cycles is 556 based on maintenance, surveillance, technical specifications and anticipated trip cycles for a 40 year qualified life.

The CPSES maintenance / surveillance program in conjunction with the CPSES preventive maintenance program for equipment located in a mild environment, is similar to the review and maintenance programs for equipment located in a harsh environment, as discussed in the CPSES FSAR Appendix 3A Section 2.4. In addition, periodic surveillance is performed to identify signs of degradation and to detect multiple failures attributable to a common cause.

Qualification of the RTBs was performed by Westinghouse. Qualification included consideration of the CPSES RTB performance specifications and significant mechanisms of degradation which could potentially affect the functionability of the breakers. Since RTBs are not expected to experience an adverse environment, the design basis event of concern is a seismic event.

Arrehenius plots were performed on the RTB non-metallic materials to demonstrate acceptable performance over a 40 year life at an ambient temperature of 5000. In addition, the shunt trip attachment non-metcllic material was thermally and mechanically aged prior to being seismically tested. Qualification was based on thermal aging using a conservative activation energy of 0.5eV and 6000. Mechanical aging included 1000 cycles, subsequent to thermal aging. Test data support that RTB components, including shunt trip attachments do not experience significant degradation due to aging.

Therefore, no maintenance beyond that described in the Westinghouse manual is required to support the RTB qualified life.

s, . Attachment to TXX-89287 'f

. . . . ,* May.31, 1989 ]

, - 'Page 3 of 3- i

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The.above information is documented in Westinghouse topical reports WCAP-8687, Supplement 2, Appendix A2,

• Equipment Qualification Test Report Materials-Aging Analysis" (Proprietary), WCAP 8687.. Supplement 2. E62A Addendum 1, l

• Equipment . Qualification Test Report DS-416 Shunt Trip Attachment and Auto Panel (Environmental and Seismic Testing)," WCAP-8687 - Supplement 2. E20A,

' Equipment Qualification Data Package," and WCAP 8587 Revision 6A,

• Methodology for Qualifying Westinghouse WRD Supplied NSSS Safety Related Electrical Equipment.' Westinghouse WCAP-8587 has been previously approved by the NRC;in a Westinghouse NSSS Safety Evaluation Report dated November 10, 1983, Given the current regulatory guidelines in IEEE 323-1983 which state that qualified lives need not be established for equipment located in a mild environment..and that-the environmental extremes and mechanical cyclic-considerations are enveloped by existing test data TU Electric believes that life testing and/or an ongoing qualification program 'is unwarranted. The CPSES maintenance and surveillance programs in conjunction with a good preventive maintenance program is adequate to maintain the reliability of the RT8s, 1

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