ML20126G770

Summary of 921215 Meeting W/Util Re Status of Plans to Replace Snubbers During Next Scheduled Unit 1 Outage in Mar 1993

ML20126G770
Person / Time
Site:	Mcguire, McGuire
Issue date:	12/21/1992
From:	Tim Reed Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
NUDOCS 9301040228
Download: ML20126G770 (41)

Text

. .- .- _ - . _ . .- . ___-. _

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', UNITED STATES

!N g ') NUCLEAR HEGULATORY COMMISSION g qE W ASHING T ON, D. C. 20bH

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Y December 21, 1992

....e Docket Hos. 50-369 and 50-370 LICENSEE: Duke Power Company FACILITY: McGuire Nuclear Station Units 1 and 2

SUMMARY

OF MEETING WITH DUKE POWER ON SNVBBER REPLACEMENT AT MCGUIRE NUCLEAR STATION On December 15, 1992, the NRC staff met with representatives of Duke Power Comptny (DPC) and Robert L. Cloud & Associates Inc. (RLCA) to discuss the status of their plans to replace snubbers with limit (formerly " seismic")

stops at McGuire Nuclear Station beginning with the next scheduled Unit 1 outage in March 1993. Meeting attendees are listed in Enclosure 1. The handouts distributed during the meeting are provided as Enclosure 2.

Following opening remarks by Pete Herran (Engineering Manager at McGuire site), Bill Taylor (DPC) and Bob Cloud (RLCA) presented the information provided in Enclosure 2. DPC views the replacement of snubbers with limit stops as an opportunity to continue to ensure and enhance current plant safety margins whila reducing O&M costs, personnel radiation exposures associated with snubber maintenance / surveillance, and ultimately freeing resources allocated to snubbers for activities that DPC views as more safety significant. The general approach to snubber replacement at McGuire relies on both the large margins inherant in the current piping / support design basis (McGuire has not used the N-411 margin for snubber reduction)'and test data that indicates limit stop performance is as good or better than snubber performance (see slides). The replacement will generally be a one-to-one replacement of snubNrs for limit stops without a detailed re-analysis for each piping system where snubbers account for 50% or less of the total dynamic supports. For systems with more than 50% snubbers, a re-analysis will be performed to identify which snubbers can be replaced with stops. DPC has identifed four piping systems that-are representative of a wide range of operating conditions, piping locations, piping sizes, and piping elevations for initial replacement of snubbers. For these four piping systems, DPC performed an analysis comparison (see slides) that indicates comparable or improved performance with linit stons versus snubbers. As indicated on the slides, DPC plans to perform a. field verification of the installed limit stops during the May-October 1993 time frame.

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December 21, 1992 DPC currently plans to implement snubber replacement using 10 CFR 50.59 (i.e., ,

there are no associated TS changes, limit stop performance is within the current design basis piping / support analysis, to date the DPC 50.59 analysis has not revealed any unreviewed safety questions) while keeping the staff informed and inviting staff feedback regarding the replacement program.

/s/

Timothy A. Reed, Project Manager Project Directorate 11-3 Division of Reactor Projects 1/11

1. List of Attendees

2. Handouts Used during Meeting cc w/ enclosures:

See next page DIS 1RifRLIE!i Docket file NRC & Local PDRs PDil-3 R/f T. Murley/F. Miraglia,12/G/18 J. Partlow,12/G/18 S. Varga G. Lainas D. Matthews T. Reed M.Hartzmann T.Chan J.Norberg L. Berry OGC, 15818 E. Jordan, MNBB3701 ACRS (10), P-315 L. Plisco, 17/0/21 E. Merschoff, Ril A. Herdt, 11 b

LA:PDl! F 11-3 PD:: I -3 LBerry Tlee DMa bews jv/q/92 j%/ [4;cdw 992 /92 DOCUMENT NAME: 121592. min

l DPC currently plans to implement snubber replacement using 10 CfR 50.59 (i.e.,

there are no associated TS changes, limit stop performance is within the current design basis piping / support analysis, to date the DPC 50.59 analysis has not revealed any unreviewed safety questions) while keeping the staff informed and inviting staff feedback regarding the replacement program.

1 l

limothy A. Reed, Project Manager Project Directorate !!-3 s Division of Reactor Projects 1/11

Enclosures:

1. List of Attendees

2. Handouts Used during Meeting cc w/ enclosures:

See next page 4

Duke Power Company McGuire Nuclear Station CC:

Mr. A. V. Carr, Esquire Mr. Dayne H. Brown, Director Duke Power Company Department of Environmental, 422 South Church Street Health and Natural Resources Charlotte, North Carolina 28242-0001 Division of Radiation Protection P. O. Box 27687 County Manager of Mecklenberg County Raleigh, North Carolina 27611-7687 720 East fourth Street Charlotte, North Carolina 28202 Mr. Alan R. Herdt, Chief Project Branch #3 Mr. R. O. Sharpe U. S. Nuclear Regulatory Commission Compliance 101 Marietta Street, NW. Suite 2900 Duke Power Company Atlanta, Georgia 30323 McGuire Nuclear Site 12700 Hagers ferry Road Ms. Karen E. Long Huntersville, NC 28078-8985 Assistant Attorney General North Carolina Department of J. Michaci McGarry, Ill, Esquire Justice Winston and Strawn P. O. Box 629 1400 L Street, NW. Raleigh, North Carolina 27602 Washington, DC 20005 Mr. R. L. Gill, Jr.

Senior Resident inspector Licensing c/o U. S. Nuclear Regulatory Duke Power Company Commission P. O. Box 1006 12700 Hagers ferry Road Charlotte, North Carolina 28201-1006 Huntersville, North Carolina 28078 Regional Administrator, Region 11 Mr. T. Richard Puryear U.S. Nuclear Regulatory Commission Nuclear Technical Services Manager 101 Marietta Street, NW. Suite 2900 Carolinas District Atlanta, Georgia 30323 Westinghouse Electric Corporation P. O. Box 32817 Mr. T. C. McHeckin Charlotte, North Carolina 28232 Vice President, McGuire Site Duke Power Company Dr. John M. Barry 12700 llagers Ferry Road Mecklenburg County lluntersville, North Carolina 28078-8985 Department of Environmental Protection 700 N. Tryon Street Charlotte, North Carolina 28202

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i 1

1

! ENCLOSURE 1 AU B QLLS l

Name Oraanization i

i Tim Reed NRC/McGuire PM Paul Guill Duke / Regulatory Compliance I

Peter Herran Duke / Engineering 4

James Leung RLCA James A. Norberg NRC/NRR/EMEB .

Mark Hartzman NRC/NRR/EMEB Charles W111 banks NUS  ;

Terence L. Chan NRC/NRR/EMEB Dob Morgan Duke /McGuire Civil Engineering R. L. Cloud RLCA W. H. (Bill) Taylor Duke /McGuire Civil Engineering i

'

• ENCLOSURE 2 i

1 l DUKE POWER COMPANY l i

i i PRESENTATION i

i l

TO

! NUCLEAR REGULATORY COMMISSION .

l ON THE McGUIRE i

i SNUBBER REPLACEMENT PROGRAM l

l USING LIMIT STOPS i

i December 15,1992  ;

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AGENDA j

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. Introduction and Purpose

. Background

. Methodology

. Piping Sample Characteristics

]

. Seisniic Response of Sample Systenis

- Snubber Supports 4

l - Limit Stop Supports

. Conclusions

. Recommendations k

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1 MEETING PURPOSE

. Present Technical Infor nation at McGuire's Request

- Describe Planned Snubber Elimination at McGuire J

- Discuss Engineering Approach &

Justification f

- Discuss Licensing Approach & Solicit Comments i

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1 . .

1 I INTRODUCTION  :

l (OVERVIEW) i l

l IT IS NOW GENERALLY RECOGNIZED THAT:

,! . There are Excessive Nuinbers of Snubbers in Nuclear Piping Systems i

4

. Snubber Failures Have Had Adverse Effects on l Plant Performance & Resources i

l

! . Snubber Maintenance and Testing Had Resulted in Significant Personnel Radiation l Exposure f

[

! . Reanalysis Can Reduce the Number of Snubbers at Existing Plants l

. Reduction Effort is Tedious and Expensive l

. Snubber Problems Remain Since Complete Elimination is Not Achievable Unless Alternate

' Supports are Used I

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{ i i l l INTRODUCTION l (PROGRAM OBJECTIVES)  !

i i

1 THE OBJECTIVES OF TILE McGUIRE PROGRAM ARE: ,

I . Demonstrate that One-to-One Replacement l Can be Implemented Without Line by Line i Reanalysis

! . Replace ALL Snubbers at McGuire 1 & 2 with -

Limit Stop Pipe Supports on a One-to-One i Substitution Basis j . Establish Exclusions to the One-to-One l Replacement Approach l

Provide Hardware Performance and Reliability

) .

l by In-Plant Installation and Inspection

! . Define the Regulatory Process for Replacing

( All Snubbers with Limit Stop Pipe Supports i

l l

I.NTRODUCTION

! (PROGRAM DESCRIPTION) i

! THE FOLLOWING ELEMENTS FORM THE IIASIS OF I

TIIE McGUIRE SNUllBER REPLACEMENT PROGRAM

. Utilize Past Analysis and Experience Data Including Experimental Results

. Perform Detail Analysis and Design for Sample i Piping Systems at McGuire l

. Develop Plant-Wide Implementation Rules for

! One-to-One Replacement

. Implement Hardware Changes for the Sample Piping Systems

. Implement Systematic Snubber Replacement for All Piping Systems

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i BACKGROUND i

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e Actual Dynninic Perforinance of Piping with l Liniit Stops is lletter Than or Equal To That i With Snubbers

)I 4 McGuire is Eligible for N-411 Daniping h

1 - Significantly Lower Scisinic Excitation

. Proposed linpleinentation of N-411 at McGuire

! - Exchange Limit Stops for Snubbers One

for One

- Maintain All Supports in Place

- No Analysis, Use N-411 Margin Inuplicitly to

Provide AdditionalInsurance for Use of Limit Stops i

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i SAMPLE ANALYSIS METHODOLOGY 1 l

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. Evolution of Met'aodology

- Acceptance of Realistic Damping, N-411

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. Consequences l - Higher Damping Lowers Pipe Stress

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SNUBBER CHARACTERISTICS IN VARIOUS SAMPLE PIPING SYSTEMS McGUIRE SAMPLE SYSTEMS PAST STUDY OR TEST SYSTESIS Case l Casel Case l Case 2 SUPPORT h CII AR ACTERISTICS SAS- CA- FW- NC- Shake MS3 Byron 2 EPRI EPRI R&D1 152 350 203 IIDR Table RIIR RCS-BP PWR BWR NO. OF DYNAMIC SUPPORTS 13 17 119 26 13 12 47 18(13)' 27 16 53 NO. OF RIGID 9 14 101 8 7 7 31 5 23 4 42 NO. OF SNUBBERS 4 3 18 18 6 5 16 13(8) 4 13 11 SNUBBER % 31 18 15 69 46 42 34 72(62) 15 81 21 TIIERMAL 0.75 0.06 0.06 0.38 0.11 0.06 0.06 0.06 0.12 0.03 0.18 MOVEMENTS @ -2.13 -0.38 -1.19 -3.13 -0.93 -1.75 -0.88 -1.38 -0.33 -0.57 -1.63 SNUBBERS (IN)

NOTE 1: Optimized Support Configuration W/13 Existing Snubbers Replaced by 8 Limit Stops

i IMPLEMENTATION RULES i

I . CRITERIA

- CASE 1: All Piping Where Snubbers Account for 50% or Less of Total Dynamic Supports i

n

- CASE 2: All Piping Where Snubbers Account for More than 50% of

Total-Dynamic Supports i

. PROCEDURE

. - CASE 1:

. Replace All Snubbers with Limit Stops on a One-for-One Basis with No Reanalysis.

Exception 1: Keep Snubbers Next to l Equipment Nozzles with Significant Thermal l Movement i

Exception 2: Keep Snubbers Attached

. to Motor-Operated Valves

- CASE 2:

. Reanalyze and Optimize Support Design Using Limit Stops, N-411 Damping,

< ISM, etc. _

i 1

i l

SUMMARY

i

l j . The Present Program was Suggested by Test Data Showing Limit Stop Supported Piping "erforms as Well or Better Than Snubber

! Supported Piping l . Comparative Analysis has been Completed on a

! Broadly Representative Sample of McGuire l Piping l

l . Original Design Basis Results were Restated to l Include Effect of Snubber Flexibility

! - Physically More Correct j - Necessary for a Uniform Comparison Basis

- Consistent with 1981 SRP

. Present .Results Show that Dynamic Response j of Sample Piping with Limit Stops & N-411 is Improved in Essentially all Respects Compared l to the Existing Installation for Both CASE 1 &

CASE 2 Piping. .

l .--

o CONCLUSIONS

. Replace All Existing Piping Snubbers with Equivalent Limit Stops for CASE 1 Piping

- Using 10CFR 50-59 Procedure

. Analyze, Optimize and Replace as Many ,

Snubbers as Possible for CASE 2 Piping BASIS

- Dynamic Response will be Diminished

- Reliability will be Improved

- Active Components will be Replaced with Passive Components

- ALARA: Radiation Exposure During Maintenance will be Diminished

- Resources Currently Allocated to Snubbers can be Re-assigned

. < v r 1

o i

i t

i l SCHEDULE l

. Project Planning April 92  !

! . Introductory NRC Presentation June 92

. Coinplete Sample Analysis

& Iniplementation Rules December 92 l . Initiate Change-Out of Snubbers with Limit Stops of Sample Systems April 93 i

! . Field Verification of l Installed Limit Stops May - October 93 l

i d