ML18033A897
| ML18033A897 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 08/18/1989 |
| From: | Michael Ray TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| TAC-62260, NUDOCS 8908230201 | |
| Download: ML18033A897 (12) | |
Text
gCCEKZRATZD D1 BUTION DEMONS ON SYSTEM J.
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REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:8908230201 DOC.DATE: 89/08/18 NOTARIZED: NO DOCKET FACIL:50-260 Browns Ferry Nuclear Power Station, Unit 2, Tennessee 05000260 AUTH.NAME AUTHOR AFFILIATION RAY,M.J.
Tennessee Valley Authority RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)
SUBJECT:
Describes program plan for resolution of flexible conduit installation issues.
DISTRIBUTION CODE:
D030D COPIES RECEIVED:LTR ENCL SIZE:
TITLE: TVA Facilities Routine Correspondence NOTES:1 Copy each to: S.Black,D.M.Crutchfield,B.D.Liaw, R.Pierson,B.Wilson 05000260 RECIPIENT ID CODE/NAME SIMMS,M GEARS,G INTERNAL: ACRS/
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TENNESSEE VALLEYAUTHORITY CHATTANOOGA. TENNESSEE 37401 5N 157B Lookout Place AUS 18 IM U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Hashington, D.C.
20555 Gentlemen:
In the Hatter of Tennessee Valley Authority Docket No. 50-260 BROHNS FERRY NUCLEAR PLANT (BFN) UNIT 2 FLEXIBLE CONDUIT PROGRAM PLAN (NRC TAC NO. 62260)
Reference:
TVA letter dated April 28,
- 1988, "Browns Ferry Nuclear Plant Electrical Issues" This letter describes the program plan for resolution of flexible conduit installation issues at Browns Ferry Nuclear Plant Unit 2. It supersedes our earlier submittal of April 28, 1988 (Reference 1).
TVA's program for evaluation of flexible conduits is outlined, in Enclosure. l.,
TVA is conducting an in-depth review of flexible conduitnstal'lations'hi'ch contain 10 CFR 50.49 cables, to ensure accommodation of seismic and thermal equipment movements.
The enclosed report provides background information, a plan for resolution, an outline of the acceptance
- criteria, and a schedule for completion of the flexible conduit issue.
A summary list of commitments is provided in Enclosure 2.
If any questions exist, please telephone Patrick P. Carier, Manager of Site Licensing at (205) 729-3570.
Very truly yours, TENNESSEE VALLEY AUTHORITY Enclosures cc:
See page 2
Mana r, Nuclea Licensing and Regulatory Affairs 85'08230201 390313 PDR ADOCK 05000260 P
PDC An Equal Opportunity Employer
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U.S. Nuclear Regulatory Commission cc (Enclosures):
Ms.
S.
C. Black, Assistant Director for Projects TVA Projects Division U.S.
Nuclear Regul'atory Commission One Nhite Flint, North 11555 Rockvi lie Pike Rockville, Maryland 20852 Mr. B. A. Hilson, Assistant Director for Inspection Programs TVA Projects Division U.S. Nuclear Regulatory Commission Region II 101 Marietta Street, NH, Suite 2900 Atlanta, Georgia 30323
.NRC Resident Inspector Browns Ferry Nuclear Plant Route 12, Box 637
- Athens, Alabama 35609-2000
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ENCLOSURE 1
TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 FLEXIBLE CONDUIT INSTALLATION FOR SEISMIC/THERMAL MOVEMENT This report i s to provide the TVA program for resolution of flexible conduit installation issues to ensure adequate seismic and thermal movement for Browns Ferry Unit 2.,
ISSUE Some flexible conduit containing Class lE cables were originally not installed to lengths necessary to ensure that the pipe conduit would not be damaged. as a result of seismic and thermal (pipe) movement.
BACKGROUND I
BFN was initially constructed using General Construction Specification G-3 entitled, "Installing Electrical Conduit Systems and Fabricated Conduit Boxes."
This specification required that flexible conduit be provided for electrical connections to equipment (such, as motors, valves, lighting fixtures),, but-contained no specific re'quirement for minimum lengths for seismic and thermal movements.
TVA recognized the need for flexible conduit length requirements to ensure adequate thermal movements for Sequoyah and future plants, and revised General Construction Specification G-40 (R3) entitled ".Installing Electrical Conduit Systems and Conduit Boxes," in October of 1980"."'owever, G-40 was not made applicable to Browns Ferry until Revision 9 was issued on January 15, 1986.
In January of 1986, TVA discovered that flexible conduit at its Watts Bar Nuclear Plant was not installed in accordance with the requirements of G-40.
Further evaluations revealed that thermal movements for pipe-mounted devices and seismic-movement for certain floor-mounted equipment were not based on worst-case conditions.
In May of 1986, a plan of action was issued to resolve this problem for all nuclear sites.
RESOLUTION TVA has issued Specification Revision Notice ll to General Construction Specification G-40, which defines the minimum conduit length for thermal and seismic movement.
Resolution of the problem requires that all flexible conduit attached to 10 CFR 50.49 devices be inspected to determine if their length is adequate for thermal and seismic movement.
Conduits not meeting the acceptance criteria of G-40 wi 1 1
be reworked to meet the criteria or wi 1 1
be technically justified as acceptable,
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CRITERIA The acceptance criteria for the inspected conduits requires the exposed conduit length between flexible conduit fittings installed at rigid conduit couplings and flexible conduit fittings at the end device, be calculated using the equation and criteria below.
FL = SD + K
- Hhere, FL Minimum exposed flexible conduit length between flexible conduit fittings.
SD Field Measured straight line distance between flexible conduit
. fittings.
(Hhen an obstacle prevents a straight line measurement of SD,
. the proposed flexible conduit route shall be determined and that distance shall be used for SD.)
K 1-inch or 4-inch (1-inch flexible conduit length is required for maximum seismic movement in. any direction); 4-inch flexible conduit length is required for maximum combined seismic/thermal movement in any direction.)
The basis for the values above are documented in TVA calculation CEB-MA2-006
- entitled, "Seismic/Thermal Movements Class lE Flexible Conduit."
This calculation defined the maximum worse case seismic/thermal movements for all TVA nuclear plants.
SCHEDULE FOR COMPLETION Approximately 500 flexible conduits have been identified which require inspection.
These inspections are being performed by TVA and are currently ongoing in conjunction with the electrical restart activities.
Since some of the conduits are being replaced as a result of modifications for, other electrical issues (i.e., cable ampacity), final completion of rework is contingent on the completion of modification activities for these other issues.
However, all flex conduit replacements required to resolve this issue will be complete prior to unit 2 restart.
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ENCLOSURE 2
Summary List of Commitments Flexible Conduit Program The following commitment will be addressed by the Nuclear Performance
- Plan, Volume 3 commitment for flexible conduit concerns.
TVA will track, followup, and ensure completion in accordance with Volume 3 and does not consider this a
new commitment.
All flexible conduit attached to 10 CFR 50.49 devices will be inspected to determine if their length is adequate for thermal and seismic movement.
Conduits not meeting the acceptance criteria of G-40 will be reworked to meet the criteria or will be technically justified as acceptable.
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