ML20116H857

Requests Approval to Use ASME Code Case N-480 for Evaluation of Pipe Wall Thinning

ML20116H857
Person / Time
Site:	Catawba
Issue date:	08/05/1996
From:	Mccollum W DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9608120283
Download: ML20116H857 (2)

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. _ ll l Dukel'ouvr Corapany Hjulw R. 5frD>u.t n JR s Caterba Nuclear Generation ikpartmcrit \lw nesident 48f)0 ConcordRoad (M3)R314M Ofthe krk, SC2J'715 (SW)33MC6 Fat l DUKEPOWER August 5, 1996 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Duke Power Company Catawba Nuclear Station, Units 1 & 2 Docket Nos. 50-413, 50-414 Request for approval to use ASME Code Case N-480 for evaluation of pipe wall thinning.

Pursuant to 10CFR 50.55a (a) (3) (i & ii), Duke Power Company requests the use of an alternative to the 1974 edition of ASME Boiler and Pressure Vessel Code, Section III for Catawba Units 1 & 2.

Specifically, Duke Power requests approval to use the provisions of ASME Code Case N-480, Examination Requirements j for Pipe Wall Thinning Due to Single Phase Erosion and  !

Corrosion, Section XI, Division 1. l This Code Case allows for the evaluation of localized pipe wall thinning and establishes allowable limits under which the pipe may remain in service.

Duke Power Company believes these requirements described in the code above create a hardship in that the repair or replacement of piping creates an exposure to unnecessary i dose and personnel hazards. Also, significant economic l impact due to extended or unplanned outages can be incurred.

During the current Unit 1 EOC9 refueling outage, wall thinning was discovered immediately downstream of the main feedwater check valves 1CF31, 40, 49 and 58. Of the four degraded sections of pipe, the "D" loop (1CF58) still passes all minimum wall requirements without further evaluation.

l The "B" loop (1CF40) piping will not pass N-480 and must be q repaired or replaced prior to returning the system to l

service. .shth; -f' I 9608120283 960005 i PDR ADOCK 05000413 P PDR

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Document Control Desk Page 2 l' August 5, 1996 i

l By invoking N-480 to evaluate loops "A" (1CF31) and "C" l

(1CF49), their replacement would not be required until 1EOC10 and would not be critical path tasks at that time.

Repair or replacement of the "A" and "C" loops would become critical path tasks and significantly impact the scheduled j startup of Unit 1. For this reason, we are requesting ,

i review and approval of this request by August 30, 1996 which is just prior to Mode 4.  ;

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! Should there be any questions concerning this change, please }

call D. Tower at (803) 831-3419. I Very truly yours, c4h - sd hh N ~

William R. McCollum, Jr.

Vice President Catawba Nuclear Station XC:

S.D. Ebneter, Regional Administrator Region II R.J. Freudenberger, Senior Resident Inspector Catawba Nuclear Station l

P.S. Tam, Senior Project Manager I' ONRR T

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