ML17333A238

Responds to NRC Concern Stated in 951120 Ltr Re Terrain Mapping & Terrain Plots in Analyzing Rotating Pancake Coil Data,Per GL 95-03

ML17333A238
Person / Time
Site:	Cook
Issue date:	12/19/1995
From:	Fitzpatrick E INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
AEP:NRC:1166AB, GL-95-03, GL-95-3, NUDOCS 9512260218
Download: ML17333A238 (5)

Text

PRIORITY CCELERATED RIDS PROCESSING) 1 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSIOK iTBR:9512260218 DOC.DATE: 95/12/19 NOTARIZED: NO DOCKET FACIL:50-315 Donald C. Cook Nuclear Power Plant, Unit 1, Indiana M 05000315 50-316 Donald C. Cook Nuclear Power Plant, Unit 2, Indiana M 05000316 AUTH. NAME AUTHOR AFFILIATION P FITZPATRICK,E. Indiana Michigan Power Co. (formerly Indiana & Michigan Ele RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) R

SUBJECT:

Responds to NRC concern stated in 951120 mapping & terrain plots in analyzing rotating pancake coil ltr re terrain data,per GL 95-03.

DISTRIBUTION CODE: AOOID COPIES RECEIVED:LTR J ENCL 0 SIZE:

TITLE: OR Submittal: General Distribution NOTES RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD3-1 LA PD3-1 PD HICKMAN,J INTERN . ~ UTER 1 NRR/DE/EMCB

'DRC CB NRR/DS SA/S PLB NRR/DSSA/SRXB NUDOCS-ABSTRACT OGC/HDS2 EXTERNAL: NOAC NRC PDR D

0 C

U NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE iVASTE! CONTACTTIIE DOCU~fENTCONTROL DESK, ROOÃf Pl-37 (EXT. 504-2083 ) TO ELIAfl.'PATE YOUR 4AifE FROif DISTRIBUTION LISTS I:OR DOCUMENTS YOU DON"I'LED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 12 ENCL ll

Indiana Michigan Power Company PO Box 16631 Coiumbus, OH 43216 lNOlANA NlCHl6AN FQWM December 19, 1995 AEP:NRC:1166AB Docket Nos.: 50-315 50-316 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Vashington, D. C. 20555 Gentlemen:

Donald C. Cook Nuclear Plant Units 1 and 2 GENERIC LETTER (GL) 95-03:

CIRCUMFERENTIAL CRACKING OF STEAM GENERATOR TUBES REQUEST FOR ADDITIONAL INFORMATION The purpose of this letter is to respond to the NRC concerns regarding terrain" mapping and terrain plots in analyzing rotating pancake coil (RPC) data.

The following is the concern stated in the enclosure to your letter to us dated November 20, 1995, and our response.

"During the Maine Yankee Outage in July/August 1994, several weaknesses were identified in their eddy current program as detailed in NRC Information Notice 94-88, "Inservice Inspection Deficiencies Result In Severely Degraded Steam Generator Tubes." In Information Notice 94-88, the staff observed that several circumferential indications could be traced back to earlier inspections when the data was reanalyzed using terrain plots. These terrain plots had not been generated as part of the original field analysis for these tubes. For the rotating pancake coil (RPC) examinations performed at your plant at locations susceptible to circumferential cracking during the previous inspection (i.e., previous inspection per your Generic Letter 95-03 response), discuss the extent to which terrain plots were used to analyze eddy current data. If terrain plots were not routinely used at locations susceptible to circumferential cracking, discuss whether or not the RPC eddy current data has been reanalyzed using terrain mapping of the data. If

~ qtergai~lots were not routinely used during the outage 9512260218,95i219 PDR ADOCK 05000315 P anaaM~.~+APDR

~

~mwaag c

U. S. Nuclear Regulatory Commission AEP:NRC:1166AB Page 2 and your data has not been reanalyzed with terrain mapping of the data, discuss your basis for not analyzing your previous data in light of the findings at Maine Yankee.

Discuss whether terrain plots will be used to analyze the RPC eddy current data at locations susceptible to circumferential cracking during your next steam generator tube inspections (i.e. the next inspection per your Generic Letter 95-03 response)."

Response

Terrain plot analysis is routinely used at the Donald C. Cook Nuclear Plant for steam generator tube RPC eddy current data analysis regardless of the inspection location. For the unit 1 steam generators, terrain plots were utilized to analyze RPC tube data collected during each of last three refueling outages. The locations typically inspected include the hot leg partial depth tube roll transitions, hot leg top of tubesheet region, and tube dents 5 volts or greater at support plate intersections. These three locations are potentially susceptible to circumferential cracking.

During the recent 1995 unit 1 refueling outage, eddy current tube inspections were conducted per our response to NRC Generic Letter 95-03 for locations identified to be susceptible to circumferential cracking. This included RPC inspection of any indication identified by the Cecco-5 probe coil inspection program for the hot leg tubesheet region and hybrid expansion ]oint (HEJ) sleeves in all steam generators. All hot leg tubesheet region indications detected by the Cecco-5 probe coil inspections at partial depth tube roll transitions and the top of tubesheet region were subsequently inspected by RPC. No indications were reported for the Cecco-5 inspection of the HEJ sleeves and therefore followup RPC inspection was not required. RPC inspection of dents 5 volts or greater was done as part of the 2 volt alternate repair criteria for tube indications at support plate intersections. RPC inspection of the U-bend sections for rows 1 and 2 tubes was also done in one steam generator. For each of the aforementioned RPC inspections terrain plots were used to analyze the RPC data.

Cook Nuclear Plant Unit 2 steam generator eddy current tube inspections for tube locations susceptible to circumferential cracking will be done as outlined in our initial response letter AEP:NRC:1166T dated June 27, 1995, to Generic Letter 95-03. The Cecco-5 probe coil will be used in the tubesheet region for hot leg tube expansion transitions. RPC inspection will be done for

U. S. Nuclear Regulatory Commission AEP'NRC:1166AB Page 3 Cecco-5 indications reported at this tube location. Analysis of the RPC data will include the use of terrain mapping.

It should be noted that the Cecco-5 probe is qualified for detection of circumferential indications in straight tube lengths, and is especially effective in the presence of dents and tube expansion transitions. However, terrain mapping techniques for Cecco-5 data have not yet been developed, so it is prudent to follow up any Cecco-5 indication with another technique, such as RPC with terrain mapping, to help characterize the indication.

Sincerely, (eF E. E. Fitzpat ick Vice President eh cc: A. A. Blind G. Charnoff H. J. Miller NFEM Section Chief NRC Resident Inspector - Bridgman J. R. Padgett