ML20237L647

Requests Written Agreement from NRC That Util Approach to Screening of Replacement Items for Seismic Sensitivity Acceptable. Summary of Seismic Adequacy of Twenty Classes of Equipment Required for Safe Shutdown... Encl

ML20237L647
Person / Time
Site:	Sequoyah
Issue date:	08/14/1987
From:	Gridley R TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
Shared Package
ML20237L651	List: ML20237L647 ML20237L665
References
NUDOCS 8708200290
Download: ML20237L647 (7)

Text

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.ej TENNESSEE VALLEY AUTHORITY t CHATTANOOGA. TENNESSEE 37401 g

SN 1578 Lookout Place 6 AUG 141987

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. U.S Nuclear Regulatory Commission Attn: Document Control' Desk ,

Washington, D.C. 20555 j Gentlemen:

! In the Matter of ) Docket Nos. 50-327 4 l'  :

Tennessee Valley Authortty ) 50-328 y .s l ' SEQUOYAH NUCLEAR PLANT (SQN) - REPLACEMENT ITEMS PROGRAM (RIP) SEISMIC l SCREENING METHODOLOGY This letter is to obtain written agreement from the staff that TVA's approach to the screening of. replacement items for selsmic sensitivity is acceptable.

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. Discussions with NRC staff resulting from the procurement inspection held at l SQN in July indicate that there is a misunderstanding of previous staff

-agreement to TVA's use.of seismic experience data to. screen past replacement I

of items in seismically quallfled equipment. TVA implemented its program on

-the basis that it had staff direction and agreement to use the methodology j that it has used to this point. The methodology implemented evolved from the '

following sequence of events.

1. January 15, 1987 - The proposed program scope.was presented to NRC at a meeting in Bethesda. The.prerestart scope included only the evaluation of all equipment that falls under the equipment qualification rule, 10 CFR 50.49. The staff wanted the prerestart scope broadened to include assurance that " equipment that falls under the scope of TVA's Design Baseline Verification Program (DV8P) will function properly during a seismic event." During the meeting; TVA proposed taking one of the DV8P systems and doing a detailed analysis of the replacements within that system. The staff rejected that proposal and suggested that TVA use seismic experience data to screen replacement items in all systems within

the 08VP Phase I scope. They suggested that TVA should have easy access to this data because TVA is already a member of the Seismic Qualification Utility Group, which sponsored the development of the database.

2. March 3, 1987 - TVA and its contractor, Earthquake Engineers, met with NRC l to describe its revised prerestart scope and the methodology for screening l replacement items for seismic sensitivity. The staff was very receptive to TVA's proposal and urged TVA to submit a program plan for the RIP. TVA agreed and reaffirmed its agreement to make its program procedures available for staff review by putting copies of those procedures in TVA's Bethesda office. 0 8708200290 870814 PDR ADOCK 05000327 b g p PDR a {

i An Equal Opportunity Employer

U.S. Nuclear Regulatory Commission 4UG 141987

3. April 1, 1987 - TVA Submitted its program plan for the Sequoyah Replacement Items Project on the SQN docket. Section 4.6.3 of the program plan discusses the evaluations that are to be performed by the Seismic Sensitivity Group within the RIP and the instruction, TI-108, by whl h these evaluations will be performed. The plan states, "The instruction is based primarily on the seismic experience data base, and uses a three-step screening process." The plan goes on to describe the three-step screening process. At the same time as the program plan submittal, TVA, pursuant to the staff's request, put TI-108 in its Bethesda office along with the other program procedures. NRC was made aware that these proced" '; were available for review through the " Update of TVA Activities" d..;a April 3, 1987.

TVA received nothing but positive feedback during the March meeting. Until the week preceding the procurement inspection, TVA had no indication from the staff that NRC in any way disagreed with the approach that TVA had taken (and implemented by the time of the inspection) to evaluate seismically sensitive replacements. Furthermore, TVA continues to assert the technical adequacy of the approach that it has taken in evaluating seismically sensitive items. The staff has recently discussed four specific maintenance activities as examples of those regarded by NRC to need further explanation of the application of the seismic experience database. Additional Information regarding those fc.or examples is enclosed for your information and review. TVA is in the process of arranging a meeting with the staff to discuss the technical aspects of this issue in greater detall. TVA hereby requests your expedited review and agreement on this issue due to its potential impact on restart of SQN unit 2.

There are no commitments related to this submittal nor are there any modifications to previous commitments. Should you have any questions about this submittal,. please direct them to J. D. Ziegler at (615) 751-8077.

Very truly yours, TENNESSEE VA LEY AUTHORITY R. L. Gridley, Director Nuclear Safe y and Licensing Enclosure cc: See page 3 i

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-U.S. Nuclear Regulatory Commission /(yg{4]gg7 l

Enclosures cc (Enclosures):.

Mr. G. G. Zech, Assistant Olrector l Regional Inspections, '

4 Division of Special. Projects- ,!

U.S. Nuclear Regulatory Commission

. Region II-

.101 Marietta Street, NW, Suite-2900 ,

Atlanta, Georgia 30323 Mr. J. A.LZwolinski, Assistant Director for Projects Olvision of TVA Projects .

Office of Special Projects U.S.. Nuclear Regulatory Commission 4350 East-West Highway EWW 322 Bethesda, Maryland' 20814 -

Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 i

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ENCLOSURE s

SEISMIC SCREENING METH000 LOGY l

This paper describes the methodology used during the " seismic screening" -

portion of the Replacement Items Program seismic sensitivity review.

Engineers performing this portion of the review are thoroughly knowledgeable in the seismic experience database as summarized in reference 1.and the ,

seismic recommendations (" caveats") outlined in reference 2 by the Senior Seismic Review and Advisory Panel (SSRAP).

Before the " seismic screening," a " classification screen" is performed by technicians using a keyword list developed by Earthquake Engineering (EQE)

' (seismic experience. database) engineers. The list provides a conservative.

method for screening a large number of items. In general, the classification

. screen does not classify an activity as seismically. sensitive, it identifies those items which are of no seismic consequence. All items which are not screened out during the classification screen are reviewed in full using the seismic experience database. Only during the " seismic. screen" is an item s

evaluated by engineers and classified as "potentially seismically sensitive" and requiring further evaluation or as being of no seismic consequence.

Four maintenance reports (MRs) were selected and are discussed below to illustrate the "selsmic screening" methodology.

MR A-299409 (See attachment 1) l <

The record documents the replacement of a meter in a diesel / generator (0/G) distribution panel. Engine / generators (and their peripherals)'are summarized as an equipment class in reference 1 (pages 22-1 through 22-8). Distribution panels are'also summarized as another distinct class of equipment in section

19. The engineer now evaluates the component to ensure that it is included'as a typical subcomponent of the equipment class. In this case, p. 22-3 of reference 1 discusses the D/G control and instrumentation. The engineer then considers the applicability of any database caveats (warning regarding this class of equipment (p. 22-8 of reference 1)). If the caveats are applicable to the work performed, then the activity receives further evaluation by the Civil Engineering Branch (CEB) or EQE walkdown to determine if any degradation of the equipment seismic ruggedness occurred. In this case, the replacement of the meter (i.e., no modification of electrical lead or alteration of mounting configuration);does not contradict the caveats. Now, the evaluation explanation is formulated. Each explanation includes a brief summary of.each

. point of the evaluation i.e., the replacement of the General Electric panel meter / ground meter in the Unit 0/ Panel G DISTRIBUTION PANEL does not affect any aspect of tne equipment associated with sources of damage in earthquakes.

(D/G DISTRIBUTION PANEL is capitalized to reference the section of " Class of 70" report which applies.)

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In summary, panel meters are subcomponents of equipment summarized in reference 1 (the section of the report is highlighted), the applicable caveats are evaluated for the subcomponent, and a determination of seismic sensitivity is made.

MR 01563 The evaluation of the D/G surge suppressors is identical to that of the '

previous meter replacement. The suppressors are identified as a typical control subcomponent of diesel generators, and the maintenance activity of suppressor replacement does not involve any caveat or recommendation applicable to the 0/G class of equipment. The explanation then reads: "The replacement of the excitation surge suppressor on the D/G (engine / generators) does not affect any aspect of the equipment related to sources of damage in l past earthquakes."

In summary, four items are referenced by this statement:

1. The maintenance activity: Replacement >

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2. The affected component: Suppressors

3. The database summary reference " engine / generators," Chapter 20, of reference 1.

4. The evaluation of the applicable caveats resulting in the statement that no sources of damage was affected.

MR 20690 The record documents the replacement of an output relay to the temperature switch. Except for a few special cases such as this, relays are referred to CEB for further evaluation. In this case, the temperature switch relay is identified as a typical subcomponent of an equipment class summarized in reference 1 (section 23, pp. 2 and 3).

See attachment 2 to summarize the evaluation of this maintenance activity:

1. The maintenance activity involved replacement of the relay 1.e., no attachments to the relay were modified. (The Maintenance Request (MR) works performed section reads " replaced output relay.")

2. Temperature switches and their associated relays are included in reference 1 as a typical subcomponent of instruments on racks (reference 1, section 23). The category is given in the explanation section of the evaluation.

3. The applicable seismic caveats (reference 4, p. 7) are not affected by the work performed.

, i MR A-529910 This record documents the replacement of a tank drain valve. The seismic screening of this activity proceeds as follows:

1. The EQE/ Seismic Qualification Users Group (SQUG) seismic experience database includes a wealth of information on piping systems and tank systems and their subcomponents; i.e., supports, vents, drains, etc.

Hand-operated or small. drain valves have demonstrated a high degree of seismic ruggedness (except as a fragile appurtenance where impact may be a concern. Replacement does not impinge on the possibility of impact damage.)

2. The-explanation statement identifies the activity and component affected (replacement, valve), the category of- the database .where the component is included (piping / piping components, as well as-tanks and engine / generators), and the conclusion of a comparison of_ piping characteristics and instances of damage to piping systems which may impinge on_the seismic ruggedness to the maintenance activity is stated.

To summarize', reference A and its caveats for maintaining the seismic ruggedness of equipment, form the basis of the engineering evaluation of maintenance activities. These caveats are based, in general, upon four {

equipment characteristic _cs which determine the seismic ruggedness of equipment as documented by the seismic experience database: Equipment mass, equipment stiffness, equipment anchorage, and the flexibility of attachments among pieces of equipment and other structural systems: Exceptions to these characteristics include specific instarices of seismic damage to equipment such I

• as relays, fragile appurtenances, etc. The application of these equipment characteristics and specific instances of seismic damage to maintenance activities at SQN provide reasonable assurance as to the seismic ruggedness of aquipment.

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, , 1 REFERENCES  ! 't - ,. g I

1~.' Earthquake Engineers Inc., February 1987, " Summary of the Seismic Adoquacy

\ of Twenty Classes of Equipment Required for the Cafe Shutdown of Nuclear 4 . q,

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') Plants." Draft was preparsd for the Seismic Qualification Utility Group.

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2. Kennedy R. P., H. A. von Reiseman, 9. Ibsnex, A.~J. Schiff, and q L. A. Hyllie Jr., (Senior Seismic Rebhw and Advisory Panel (SSRAP)),

I March 1987. "UseofSeismicExper@ptetoSnowRuggednessofEquipmentin Nuclear Power Plants." Draf t wdgropared for, Seismic Qualification ,

Utility Group. Washington, DC; U.S. Nv;1 ear Ppulatory Commission. j .

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