ML082530144

Upcoming Steam Generator Tube Inservice Inspection

ML082530144
Person / Time
Site:	Byron
Issue date:	09/12/2008
From:	David M Plant Licensing Branch III
To:	Pardee C Exelon Generation Co
David, Marshall - DORL 415-1547
References
TAC MD9590
Download: ML082530144 (5)

Text

Mr. Charles G. Pardee September 12, 2008 Chief Nuclear Officer and Senior Vice President Exelon Generation Company, LLC 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

BYRON STATION, UNIT NO. 2 - UPCOMING STEAM GENERATOR TUBE INSERVICE INSPECTION (TAC NO. MD9590)

Dear Mr. Pardee:

Inservice inspections of steam generator (SG) tubes play a vital role in assuring SG tube integrity. The reporting requirements of plant technical specifications typically require submission of a report within 180 days following completion of the inspection. The content of the report includes the following:

1. The scope of inspections performed on each SG,

2. Active degradation mechanisms found,

3. Nondestructive examination techniques utilized for each degradation mechanism,

4. Location, orientation (if linear), and measured sizes (if available) of service induced indications,

5. Number of tubes plugged during the inspection outage for each active degradation mechanism,

6. Total number and percentage of tubes plugged to date, and

7. The results of condition monitoring, including the results of tube pulls and in-situ testing.

A telephone conference has been arranged with members of your staff to discuss the ongoing results of the SG tube inspections to be conducted during the upcoming Byron Station, Unit No. 2, refueling outage. This telephone conference will occur after the majority of the tubes have been inspected, but before the SG inspection activities have been completed. Enclosed is a list of discussion points to facilitate the conference.

The U.S. Nuclear Regulatory Commission (NRC) staff will document a summary of the telephone conference, as well as any material that you may have provided to the NRC staff in support of the conference.

Sincerely,

/RA/

Marshall J. David, Senior Project Manager Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. STN 50-455

Enclosure:

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

ML082530144

• Per e-mail dated 9/5/08 NRR-106 OFFICE LPL3-2/PM LPL3-2/LA DCI/CSGB/BC LPL3-2/BC NAME MDavid THarris AHiser*

RGibbs DATE 9 /11/08 9/10/08 09/05/08 9/12/08 Byron Station, Unit No. 2 cc:

Corporate Distribution Exelon Generation Company, LLC Via e-mail Byron Distribution Exelon Generation Company, LLC Via e-mail Illinois Emergency Management Agency Division of Nuclear Safety Via e-mail Mr. Dwain W. Alexander, Project Manager Westinghouse Electric Corporation Via e-mail Howard A. Learner Environmental Law and Policy Center of the Midwest Via e-mail Byron Resident Inspector U. S. Nuclear Regulatory Commission Via e-mail Attorney General Springfield, IL Via e-mail Ms. Lorraine Creek RR 1, Box 182 Manteno, IL 60950 Chairman, Ogle County Board Via e-mail Will County Executive Via e-mail Mr. Barry Quigley Via e-mail

Enclosure STEAM GENERATOR TUBE INSPECTION DISCUSSION POINTS PREPARED BY THE OFFICE OF NUCLEAR REACTOR REGULATION BYRON STATION, UNIT NO. 2 DOCKET NO. 50-455 The following discussion points have been prepared by the U.S. Nuclear Regulatory Commission (NRC) staff to facilitate the phone conference arranged with the licensee to discuss the results of the steam generator (SG) tube inservice inspections to be conducted during the upcoming Byron Station, Unit No. 2, refueling outage. This telephone conference is scheduled to occur towards the end of the planned SG tube inspection interval, but before the unit completes the inspections and repairs.

The NRC staff plans to document a summary of the phone conference, as well as any material that is provided in support of the phone conference.

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 SG, 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 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). 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.

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 (including the source or nature of the loose part, if known) if the loose parts were removed from the SG 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 SG-related activities during the remainder of the current outage.