ML18037A450

Forwards Request for Addl Info Re Medium Voltage Cable Bend Radius at Plant

ML18037A450
Person / Time
Site:	Browns Ferry
Issue date:	08/23/1993
From:	Hebdon F Office of Nuclear Reactor Regulation
To:	Medford M Tennessee Valley Authority
References
TAC-M86253, TAC-M86254, TAC-M86255 NUDOCS 9309080282
Download: ML18037A450 (8)

Text

Docket Nos.

50-259, 50-260, and 50-296 August 23, 1993 Dr. Mark O. Medford,.Vice President Technical Support Tennessee Valley Authority 3B Lookout Place 1101 Har ket Street Chattanooga, Tennessee 37402-2801

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING MEDIUM VOLTAGE CABLE BEND RADIUS -

BROWNS FERRY UNITS 1, 2, AND 3 (TAC NOS.

H86253, H86254, AND M86255)

By letter dated March 17,

1993, the Tennessee Valley Authority (TVA) requested a safety evaluation by the NRC staff of changes to TVA's program to resolve concerns associated with medium voltage cable bend radius at the Browns Ferry Nuclear Plant (BFN) Units 1, 2, and 3.

The NRC staff has examined the TVA submittal, and has determined additional information is needed to complete its review.

The requested information is described in the enclosure to this letter.

Please contact Joe Williams at (301)504-1470 if you have any questions regarding this request.

This request affects nine or fewer respondents, and therefore is not subject to Office of Management and Budget review under P.L.56-911.

Sincerely,

Enclosure:

Request for Additional Information cc w/enclosure:

See next page Original signed by Mohan C. Thadani for Frederick J.

Hebdon, Director Project Directorate II-4 Division of Reactor Projects I/II Office of Nuclear Reactor Regulation OFFICE:

NAME:

DATE PDI I-4/L BC1 9

/C~/93 PDII-4/PM JWil 1 i a f//~/93 PDI I-4/PM TRoss 4 /~>/93 PD I I-4/PM DTrimble +

0 /u /93 DII-4/

FHebdon DOCUMENT NAME':iBFNiCABLERAI.LTR 9309080282 930823 PDRd "ADOCK~ 05000259

'/

P 'DR ~/l.

Tennessee Valley Authority ATTN:

Dr. Mark 0. Medford Browns Ferry Nuclear Plant CC:

Mr.

W.

H. Kennoy, Director Tennessee Valley Authority ET 12A 400 West Summit Hill Drive Knoxville, Tennessee 37902 Mr.

R.

M. Eytchison, Vice President Nuclear Operations Tennessee Valley Authority 3B Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801 Site Licensing Manager Browns Ferry Nuclear Plant Tennessee Valley Authority P.O.

Box 2000

Decatur, Alabama 35609-2000 Mr. 0. J. ler'.ngue, Vice President Browns Ferry Nuclear Plant Tennessee Valley Authority P.O.

Box 2000

Decatur, Alabama 35609-2000 Mr. B.

S. Schofield, Manager Nuclear Licensing and Regulatory Affairs Tennessee Valley Authority 5B Lookout Place 1101 Market Street Chattanooga, Tennessee 37402-2801 TVA Representative Tennessee Valley Authority 11921 Rockville Pike Suite 402 Rockville, Maryland 20852 General Counsel Tennessee Valley Authority ET 11H "00 West Summit Hill Drive Knoxvil]e, Tennessee 37902 State Health Officer Alabama Dept. of Public Health 434 Monroe Street Montgomery, Alabama 36130-1701 Regional Administrator U.S.N.R.C.

Region II 101 Marietta Street, N.W.

Suite 2900

Atlanta, Georgia 30323 Mr. Charles Patterson Senior Resident Inspector Browns Ferry Nuclear Plant U.S.N.R.C.

Route 12, Box 637

Athens, Alabama 35611

Manager, Nuclear Assurance and Licensing Browns Ferry Nuclear Plant Tennessee Valley Authority P. 0.

Box 2000

Decatur, Alabama 35609-2000

Chairman, Limestone County Commission P.O.

Box 188

Athens, Alabama 35611

Distribution Docket File-

. NRC- & Local PDRs BFN Reading S.

Varga G. Lainas F.

Hebdon B. Clayton J. Williams T.

Ross D. Trimble E. Herschoff, RII P. Kellogg, RII R. Crlenjak, RII OGC ACRS(IO)

'I

ENCLOSURE RE)UEST FOR ADDITIONAL INFORMATION BROWNS FERRY'EDIUM VOLTAGE CABLE BEND RADIUS Replacement of Group 1 cables ES2550-11, ES75-I, ES88-I, and ES113-I was planned based upon the original BFN Unit 2 walkdowns.

TVA claims subsequent constructability walkdowns found that these cables do not require replacement because the original walkdown data was incorrect.

The NRC staff requests the following information for these cables:

a.

Provide the number of bends involved and the remeasured bend radius values for these cables.

b.

Provide information on how the ratio of bend radius to cable outside diameter (OD) of 2.95 for cable ES113-I and 3.37 for ES2550-II per the original walkdown were remeasured to over six times the cable 00.

Were the four cables retrained after the original walkdown?

c.

Are there any cable bend concerns for the cables installed in BFN Units 1 and 3?

Are there any changes in the cable group classifications of BFN Units 1

and 3?

. d.

Justify that the sampling program used to validate the original walkdown results is sufficient to give a 95K confidence that 95% of the original walkdown bend data is adequate.

The staff is concerned a fail that a change in a cable group classification could be consid r d

'd sample, and that some cable configurations may have changed after the initial walkdowns.

Using an acceptance criterion based on a change in group classification would substantially increase sample size requirements, because the four reclassified cables would be considered failures.

Therefore, the staff requests addition l d'scussion and justification of the sampling acceptance criterion.

i iona Provide objectives and details of the Load Cycle and Corona testing, including, as a minimum, purpose of the test, the test procedure, test apparatus

required, place of the test, test voltage and its basis, parameters

measured, and acceptance criteria.

a.

Is this test applicable to all medium voltage power cables?

b.

Will installed cables be used for this test?

If not, provide justification for applying the test results to installed cables.

If installed cables are not used, how are aging effects accounted for?

c.

Pi ovide references to any applicable IEEE, ANSI, or other standards which recognize Load Cycle and Corona testing for detection of cable damage due to excessive bends in installed cables.

d.

Will Load Cycle and Corona testing be applied to all Group 2 cables?

e.

Provide details about routine cable maintenance, including any testing.

TYA stated that a

Load Cycle and Corona test program has been used in the disposition of similar issues for Watts Bar.

a.

What is meant by-"similar issues" ?

b.

Is TVA planning to retrain BFN Group 2 cables to a radius of eight times the cable 00 as at Watts Bar?

c.

Provide the basis and rationale for the adequacy of this test for BFN cables.

Provide the conduit bend radii for embedded cables.

I P