ML15097A170

Response to NRC Request for Additional Information Regarding 2014 Steam Generator Tube Inspections

ML15097A170
Person / Time
Site:	Palo Verde
Issue date:	04/01/2015
From:	Weber T Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
102-07029-TNW/MDD/CJS
Download: ML15097A170 (7)

Text

Technical Specification 5.6.8 9aps Palo Verde Nuclear Generating Station 102-07029-TNW/MDD/CJS 5801 S. Wintersburg Road Tonopah, AZ 85354 April 1, 2015 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS) Unit 2 Docket No. STN 50-529 License No. NPF-51 Response to NRC Request for Additional Information Regarding 2014 Steam Generator Tube Inspections Attached please find Arizona Public Service Company's (APS) response to the March 10, 2015, Nuclear Regulatory Commission (NRC) Request for Additional Information (RAI).

By letter dated October 10, 2014 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML14288A371), APS submitted information summarizing the results of the 2014 steam generator tube inspections at Palo Verde Nuclear Generating Plant (PVNGS) Unit 2.

The NRC staff reviewed the information provided by APS and determined that additional information was needed to complete its review of the steam generator tube inspections. On March 10, 2015, the NRC staff provided an RAI to APS, which requested that a response be submitted within 30 days. The APS response to the RAI is provided in the Enclosure to this letter.

No commitments are being made to the NRC by this letter. Should you need further information regarding this response, please contact Michael D. Dilorenzo, Licensing Section Leader, at (623) 393-3495.

Sincerely, Thomas N. Weber Nuclear Regulatory Affairs Department Leader TNW/MDD/CJS/hsc A .D1 A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway a Diablo Canyon 0 Palo Verde 0 Wolf Creek

102-07029-TNW/MDD/CJS ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Response to NRC Request for Additional Information Regarding 2014 Steam Generator Tube Inspections Page 2

Enclosure:

Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2 cc:

M. L. Dapas NRC Region IV Regional Administrator M. M. Watford NRC NRR Project Manager for PVNGS C. A. Peabody NRC Senior Resident Inspector for PVNGS

Enclosure Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2

Enclosure Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2 Introduction By letter dated October 10, 2014 (Agencywide Documents Access and Management Systems (ADAMS) Accession No. ML14288A371), Arizona Public Service Company (APS) submitted information summarizing the results of the 2014 steam generator tube inspections at Palo Verde Nuclear Generating Plant (PVNGS) Unit 2.

The NRC staff reviewed the information provided by APS and determined that additional information was needed to complete its review of the steam generator tube inspections. On March 10, 2015, the NRC staff provided a Request for Additional Information (RAI) to APS, which requested that a response be submitted within 30 days. The APS response to the RAI is provided as follows.

NRC Reauest 1 For each operatingcycle since steam generatorreplacement in 2003, please provide the effective full power months (EFPM) accrued, and the cumulative EFPM as of RF018.

APS Response The EFPM and cumulative EFPM accrued for each operating cycle since steam generator replacement in 2003 is provided in the following table.

I PVNGS Unit 2 Operating Cycles Since 2003 Operating Cycles EFPM Cumulative EFPM Cycle 12 (Ended Spring 2005) 14.72 14.72 Cycle 13 (Ended Fall 2006) 15.73 30.45 Cycle 14 (Ended Spring 2008) 15.97 46.42 Cycle 15 (Ended Fall 2009) 15.27 61.69 Cycle 16 (Ended Spring 2011) 15.96 77.65 Cycle 17 (Ended Fall 2012) 17.12 94.77 Cycle 18 (Ended Spring 2014) 16.51 111.28 I

Enclosure Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2 NRC Reauest 2 In the section labeled "UpperInternals Inspection Summary" on pages 7 and 8, the phrases "no anomalies were noted" and "no anomalous conditions were noted" are used when discussing various sections of the upper internals. Please discuss whether any degradationwas noted during these inspections. Similarly, please clarify whether any degradation was observed during the channel head and plug inspections.

APS Response As stated on page 7 of the Unit 2 - 1 8 th Refueling Outage Steam Generator Tube Inspection Report, the majority of the upper internals inspection for steam generator SG 21 was not performed during the outage.

A visual inspection was performed on the upper internals of steam generator SG 22.

The visual examinations documented the overall condition of the components in the accessible areas above the primary separator deck and below the primary separator deck (inside the shroud). The upper hand hole was opened and a camera was inserted into the no-tube lane to inspect the top of the 7 th eggcrate tube support, the bottom of the 8 th eggcrate tube support and the center stay opening.

Specific areas visually examined during the inspection above the primary separator deck included 194 steam separators, drain lines, bottom of the dryer deck, bottom of the dryers and accessible nozzles.

Specific areas visually examined below the primary separator deck included I-Beam attachments, recirculation piping and nozzles, recirculation pipe stanchions, U-bolt attachments and vanes underneath the primary separators. The square bend region was visually inspected including the tube bundle in this area, diagonal supports and vertical supports. The square bend region showed evidence of scale deposits.

No degradation was documented on any of the components that were visually inspected.

The downcomer feed ring was not inspected. The PVNGS replacement steam generators downcomer feedwater rings are constructed of chrome-moly carbon steels and erosion/corrosion is not considered relevant for the PVNGS replacement steam generators at the current accumulated EFPM.

Procedure 81DP-9RC01, PVNGS Steam GeneratorManagement Program, requires that a visual inspection of the steam generator plugs be performed to assess plug integrity, consistent with the EPRI PWR Steam GeneratorExamination Guidelines. A visual examination was conducted in both SG 21 and SG 22. No evidence of plug leakage was identified. The results are documented on plug examination sheets 2

Enclosure Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2 that have been signed and attached to the procedure in the eddy current testing work orders.

A channel head inspection was also performed in response to industry operating experience. No degradation was identified during the channel head inspections.

NRC Reauest 3 Table 2 provides the number of tubes and number of indicationsdetected. Please clarify the number of tubes and the number of indications (regardlessof depth) with wear in the U-bend region (batwings and vertical straps) and at the horizontal (straightspan) tube supports.

APS Response The following figure (Revised Table 2 of the Unit 2 - 1 8 th Refueling Outage Steam GeneratorTube Inspection Report) documents the specific inspection results for the U-bend region (batwings and vertical straps) and at the horizontal (straight span -

"eggcrate") tube supports.

3

Enclosure Response to Request for Additional Information for Steam Generator Tube Inspections in Unit 2 Figure TABLE 2 Revised 3-17-15 INDICATION

SUMMARY

DAMAGE STEAM GENERATOR STEAM GENERATOR MECHANISM 21 22 Tubes Indications BW VS EC Tubes Indications BW VS EC WEAR 1%- 190% 447 503 275 201 27 763 881 410 418 53 20% - 29% 25 25 14 11 0 78 86 49 36 1 30% -39% 4 4 3 1 0 9 9 7 2 0

> 4001 0 0 0 0 0 2 2 2 0 0 PLUGGED (10) (26)

Possible Loose Parts (Rotating Coil)

PLUGGED (0) (29 PREVENTATIVE 00 PLUGGED (10) (29)

TOTAL PLUGGED

% / (177 / 1.4%) (206 / 1.6%)

NOTES:

1. Numbers in (X) are tubes numbers plugged in each category

2. The "Tube" column above represents Bobbin Coil results for the number of tubes; using the largest wear indication

3. The "Indications" column above represents Bobbin Coil results for the number of wear indications

4. The three PLI (wear caused by a loose part) represent the tubes discussed in the SG22 Foreign Object Summary paragraphs in Section 8.

LEGEND:

BW - batwing VS - vertical strap EC - eggcrate 4