ML050400428

Upcoming Steam Generator Tube Inservice Inspection

ML050400428
Person / Time
Site:	Fort Calhoun
Issue date:	02/09/2005
From:	Wang A NRC/NRR/DLPM/LPD4
To:	Ridenoure R Omaha Public Power District
Wang A,/NRR/DLPM/415-1445
References
TAC MC5776
Download: ML050400428 (6)

Text

February 9, 2005 Mr. R. T. Ridenoure Division Manager - Nuclear Operations Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.

Post Office Box 550 Fort Calhoun, NE 68023-0550

SUBJECT:

FORT CALHOUN STATION, UNIT NO. 1 - UPCOMING STEAM GENERATOR TUBE INSERVICE INSPECTION (TAC NO. MC5776)

Dear Mr. Ridenoure:

Inservice inspections of steam generator (SG) tubes play a vital role in assuring that adequate structural integrity of the tubes is maintained. As required by the plant's technical specifications, reporting requirements range from submitting a special report, within 15 days following completion of each inservice inspection of SG tubes, that identifies the number of tubes plugged and/or repaired; to submitting a special report, within 12 months following completion of the inspection, that provides complete results of the SG tube inservice inspection.

The special report containing the complete results of the inspection shall include the following:

1. Number and extent of tubes inspected.

2. Location and percent of wall-thickness penetration for each indication of an imperfection.

3. Identification of tubes plugged and/or repaired.

A phone conference will be arranged with members of your staff to discuss the ongoing results of the SG tube inspections to be conducted during the upcoming Fort Calhoun Station, Unit 1 refueling outage. We would like to have this phone call after the majority of the tubes have been inspected, but before the SG inspection activities have been completed. The preferable time would be when the SG inspection is approximately 70 percent complete. Enclosed is a list of discussion points to facilitate this phone conference.

R. Ridenoure The staff plans to document a brief summary of the conference call as well as any material that you may have provided to the staff in support of the call.

Sincerely,

/RA/

Alan B. Wang, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285

Enclosure:

List of Discussion Points cc w/encl: See next page

R. Ridenoure February 9, 2005 The staff plans to document a brief summary of the conference call as well as any material that you may have provided to the staff in support of the call.

Sincerely,

/RA/

Alan B. Wang, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-285

Enclosure:

List of Discussion Points cc w/encl: See next page DISTRIBUTION:

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STEAM GENERATOR TUBE INSPECTION DISCUSSION POINTS PREPARED BY THE OFFICE OF NUCLEAR REACTOR REGULATION OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION, UNIT 1 DOCKET NO. 50-285 The following discussion points have been prepared to facilitate the phone conference arranged with Omaha Public Power District to discuss the results of the steam generator (SG) tube inspections to be conducted during the upcoming Fort Calhoun Station, Unit 1 refueling outage.

This phone call is scheduled to occur towards the end of the planned SG tube inspection interval, but before the unit completes the inspections and repairs (approximately 70 percent complete).

The staff plans to document a brief summary of the conference call as well as any material that is provided in support of the call. Please be prepared to discuss the following:

1. Discuss any trends in the amount of primary-to-secondary leakage observed during the recently completed cycle.

2. Discuss whether any secondary side pressure tests were performed during the outage and the associated results.

3. Discuss any exceptions taken to the industry guidelines.

4. For each steam generator, provide a description of the inspections performed including the areas examined and the probes used (e.g., dents/dings, sleeves, expansion-transition, U-bends with a rotating probe), the scope of the inspection (e.g., 100 percent of dents/dings greater than 5 volts and a 20 percent sample between 2 and 5 volts), and the expansion criteria. Also, discuss the extent of the rotating probe inspections performed in the portion of tube below the expansion-transition region (reference NRC Generic Letter 2004-01, "Requirements for Steam Generator Tube Inspections").

5. For each area examined (e.g., tube supports, dent/dings, sleeves, etc), provide a summary of the number of indications identified to-date of each degradation mode (e.g.,

number of circumferential primary water stress corrosion cracking indications at the expansion-transition). For the most significant indications in each area, provide an estimate of the severity of the indication (e.g., provide the voltage, depth, and length of the indication). In particular, address whether tube integrity (structural and accident induced leakage integrity) was maintained during the previous operating cycle. In addition, discuss whether any location exhibited a degradation mode that had not

previously been observed at this location at this unit (e.g., observed circumferential primary water stress corrosion cracking at the expansion-transition for the first time at this unit).

6. Describe repair/plugging plans.

7. Describe in-situ pressure test and tube pull plans and results (as applicable and if available).

8. Provide the schedule for steam generator-related activities during the remainder of the current outage.

9. Discuss the following regarding loose parts:

• what inspections are performed to detect loose parts,

• a description of any loose parts detected and their location within the SG,

• if the loose parts were removed from the SG,

• indications of tube damage associated with the loose parts, and

• the source or nature of the loose parts if known.

10. Discuss whether any circumferential indications were identified at any location other than: (1) at or below the expansion-transition, (2) in the chord region, or (3) at drilled hole support plates. Please discuss whether any freespan circumferential indications were detected outside a critical area. Please clarify whether there are any unique circumstances (e.g., dents/dings) at the location of these indications. If not, discuss the basis for the scope of inspection around the tube support (e.g., from 2-inches above and below the centerline of the support).

11. Discuss any multiple indications that were identified (such as the parallel circumferential cracks identified at the 8th support plate in 2003) and the potential that these indications are interacting (e.g., the burst pressure or leakage of one of the flaws is affected by the proximity of the other flaws).

12. During past inspections a 20 percent sample of the bobbin indications previously inspected with a rotating probe and which showed no change from previous bobbin coil data were retested with a rotating probe in order to validate the analysis methodology.

Discuss the results of any such analysis verification performed during this outage.

13. During the 2003 inspection several indications were identified within the influence region of the drilled support plates. These indications were directly above or below drilled supports but were not encompassed by the support. Please discuss any freespan indications attributed to the drilled supports. Are there dents associated with these indications? In addition, discuss the basis for selecting 2-inches above and below the center of the support as an adequate inspection area for the drilled supports.

Ft. Calhoun Station, Unit 1 cc:

Winston & Strawn Mr. Daniel K. McGhee ATTN: James R. Curtiss, Esq. Bureau of Radiological Health 1400 L Street, N.W. Iowa Department of Public Health Washington, DC 20005-3502 401 SW 7th Street, Suite D Des Moines, IA 50309 Chairman Washington County Board of Supervisors P.O. Box 466 Blair, NE 68008 Mr. John Hanna, Resident Inspector U.S. Nuclear Regulatory Commission P.O. Box 310 Fort Calhoun, NE 68023 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-4005 Ms. Sue Semerera, Section Administrator Nebraska Health and Human Services Systems Division of Public Health Assurance Consumer Services Section 301 Cententiall Mall, South P.O. Box 95007 Lincoln, NE 68509-5007 Mr. David J. Bannister, Manager Fort Calhoun Station Omaha Public Power District Fort Calhoun Station FC-1-1 Plant P.O. Box 550 Fort Calhoun, NE 68023-0550 Mr. John B. Herman Manager - Nuclear Licensing Omaha Public Power District Fort Calhoun Station FC-2-4 Adm.

P.O. Box 550 Fort Calhoun, NE 68023-0550