ML22294A081

Nrc/Duke Steam Generator Inspection Call for November 8, 2022

ML22294A081
Person / Time
Site:	Oconee
Issue date:	10/21/2022
From:	Shawn Williams Plant Licensing Branch II
To:	Vaughn J Duke Energy Carolinas
Williams S
References
Download: ML22294A081 (2)

Text

From: Shawn Williams To: Vaughan, Jordan L

Subject:

Oconee, Unit 1 - NRC/Duke Steam Generator Inspection Call for Oconee, Unit 1 Date: Friday, October 21, 2022 11:43:53 AM Mr. Vaughn, Inservice inspections of steam generator (SG) tubes play a vital role in assuring SG tube integrity. On occasion, NRC staff from the NRR/DNRL, Corrosion and Steam Generator (NCSG) Branch requests a voluntary non-billable conference call with the licensee to discuss ongoing SG tube inspections during the outage, at approximately 80% completion of the inspection.

Duke was agreeable to holding a conference call with U.S. Nuclear Regulatory Commission (NRC) staff to discuss the ongoing results of the SG tube inspections at Oconee, Unit 1, on November 8, 2022, 4-5pm.

Upon completion of the call, NRC staff will document a publicly available summary of the conference call.

Below is a list of discussion points to facilitate this call.

STEAM GENERATOR TUBE INSPECTION DISCUSSION POINTS

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.

5. For each area examined (e.g., tube supports, dent/dings, sleeves, etc), provide the following:

a. A summary of the number of indications identified to date for each degradation mode (e.g., number of circumferential primary water stress corrosion cracking indications at the expansion transition).

b. For the most significant indications in each area, provide an estimate of the severity of the indication (e.g., voltage, depth, and length of the indication), including whether tube integrity (structural and accident induced leakage integrity) was maintained during the previous operating cycle. In addition, discuss any analyses performed specifically for the most significant indications to demonstrate tube integrity.

c. 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. Discuss the following regarding loose parts:

a. The inspections performed to detect loose parts.

b. A description of any loose parts detected and their location within the SG (including the source or nature of the loose part, if known).

c. If the loose parts were removed from the SG.

d. Indications of tube damage associated with the loose parts.

9. Discuss the scope and results of any secondary side inspection and maintenance activities (e.g., in-bundle visual inspections, feedring inspections, sludge lancing, assessing deposit loading, etc).

10. Discuss any unexpected or unusual results.

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

Sincerely, Shawn A. Williams, Senior Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-269

Enclosure:

Steam Generator Tube Inspection Discussion Points