ML13189A232

Summary of Conference Telephone Call Regarding the 2013 Steam Generator Tube Inspections

ML13189A232
Person / Time
Site:	Cook
Issue date:	07/15/2013
From:	Thomas Wengert Plant Licensing Branch III
To:	Weber L Indiana Michigan Power Co
Wengert T
Shared Package
ML13189A226	List: ML13189A222 ML13189A232
References
TAC MF0875
Download: ML13189A232 (5)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555*0001 July 15, 2013 Mr. Lawrence J. Weber Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106

SUBJECT:

DONALD C. COOK NUCLEAR PLANT, UNIT 1 -

SUMMARY

OF CONFERENCE TELEPHONE CALL REGARDING THE 2013 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MF0875)

Dear Mr. Weber:

On April 12, 2013, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference call with Indiana Michigan Power Gompany (I&M) representatives regarding the ongoing steam generator (SG) tube inspection activities conducted during the 2012 outage at the Donald C. Cook Nuclear Plant, Unit 1. The NRC follows the results of the industry's SG inspections in order*to maintain an awareness of the condition of the SGs and the types of tube degradation mechanisms that are active.

The enclosed documentation of the telephone call is provided to I&M for information. The information provided by I&M in support of the discussion (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13189A222) is available to the public. Based on the information provided during the conference call, the NRC staff did not identify any issues that warranted additional follow-up action at this time. If there are any questions, please contact me at 301-415-4037.

Sincerely, Thomas J. Weng , Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket No. 50-315

Enclosure:

Conference Call Summary cc w/encl: Distribution via ListServ

SUMMARY

OF CONFERENCE CALL WITH INDIANA MICHIGAN POWER COMPANY REGARDING THE SPRING 2013 STEAM GENERATOR TUBE INSPECTION RESULTS DONALD C. COOK NUCLEAR PLANT, UNIT 1 DOCKET NUMBER 50-315 On April 12, 2013, the Nuclear Regulatory Commission (NRC) staff participated in a conference call with Indiana Michigan Power Company (the licensee) representatives regarding ongoing steam generator (SG) tube inspection activities at Donald C. Cook Nuclear Plant (CNP), Unit 1.

In support of the conference call, the licensee provided a document summarizing some of the inspection results. This document is located in the NRC's Agencywide Documents Access and Management System (ADAMS) at Accession No. ML13189A222.

CNP Unit 1 has four model 51 R recirculating SGs designed and fabricated by Babcock and Wilcox International. Each SG has 3,496 thermally treated, Alloy 690 tubes that have an outside diameter of 0.875 inches, and a nominal wall thickness of 0.049 inches. The tubes are

. supported by Type 410 stainless steel, lattice-grid tube supports, and flat fan bars. The tubes were hydraulically expanded at each end for the full depth of the tubesheet.

Information provided by the licensee is summarized below:

• At the time of the call the licensee indicated that it was approximately 75 percent complete with SG tube inspections and that the results of the inspections are consistent with their expectations (projections). The maximum wear depth expected during this inspection is 33 percent through wall. At the time of the call the maximum depth detected was 32 percent through wall. The licensee stated that 1200 new indications were projected, but only 450 had been detected at the time of the call.

• The licensee indicated that the average through wall wear growth for SGs 11, 12, 13, and 14 are 2.7, 3.0,2.8, and 1.76 percent, respectively. The standard deviation ranged from 1.18 to 1.62 percent.

• The extent of the X-probe inspections at the top of the tubesheet (ITS) is from the tube end to the first support. The tubes inspected included all tubes around the periphery of the tube bundle and all tubes adjacent to the divider lane. This is the first outage that the X-probe is being used at CNPUnit 1.

o There are approximately 20 tubes per SG that have wear scars greater than 20 percent though wall.

• The licensee indicated that there was a typographical error on page 2 of their notes.

The "Lattice Grid Significant Indications" is not at the "fan bar" but rather at "lattice grid 4."

Enclosure

-2

• The licensee indicated that it performed SG channel head inspections. In particular, the tubesheet, divider plate, and cladding were inspected and nothing abnormal was reported.

• During the last SG inspection outage, 100 percent of the tubes were inspected. There was an unexpected increase in the number of indications of wear. The root cause for the large number of wear indications was that the SGs are operating close to a resonant condition. The original SGs were originally designed to operate at a primary pressure of 2235 pounds per square inch (psi) and a temperature of 574°F. To extend the life of the original SGs, plant primary pressure and temperature were reduced (prior to the replacement in 2000) to 2085 psi and 556°F, respectively. To address the increase in the number of wear indications, the licensee plans to restore primary pressure and temperature to their original values of 2235 psi and 574°F during the next refueling outage. This should result in secondary side pressure increasing from 650 psi to 800 psi which should move the SG out of the resonant condition. After one cycle of operating at the increased reactor coolant system pressure and temperature, the licensee currently plans another SG tube inspection outage to confirm the adequacy of their corrective actions.

• The licensee plans to inspect 100 percent of the tubes during the next refueling outage.

• Foreign object search and retrieval was currently ongoing in SG 11. Three objects had been identified. Two were retrieved, and attempts to retrieve the third object were scheduled for later in the day.

• Additional inspections of the foreign object in SG 13 will be performed to determine the nature of the object and to attempt to retrieve it.

• The licensee indicated that if a foreign object cannot be removed, they will perform an engineering evaluation and will most likely stabilize and plug the tubes surrounding the part. .

• Only 75 pounds of sludge were removed during sludge lancing operations in the prior outage, and this was after 3 cycles of operation. Prior deposit mapping indicated about 800 pounds of deposits are in the SGs.

The following abbreviations are used in the document provided by the licensee:

CL = cold leg

=

ECT eddy current test

=

EPRI Electric Power Research Institute

=

FO foreign object

=

FOSAR foreign object search and retrieval

=

HL hot leg

=

MFP main feedwater pump NEI =Nuclear Energy Institute

=

PLP possible loose part

=

SI special interest

- 3 SSI :: secondary side inspection*

ITS:: top of tubesheet TW:: through wall The NRC staff did not identify any issues that required follow-up action at this time; however, the staff asked.to be notified in the event that any unusual conditions were detected during the remainder of the outage or if a tube fails an in-situ pressure test.

July 15, 2013 Mr. Lawrence J. Weber Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106

SUBJECT:

DONALD C. COOK NUCLEAR PLANT, UNIT 1 -

SUMMARY

OF CONFERENCE TELEPHONE CALL REGARDING THE 2013 STEAM GENERATOR TUBE INSPECTIONS (TAC NO. MF0875)

Dear Mr. Weber:

On April 12, 2013, the U.S. Nuclear Regulatory Commission (NRC) staff participated in a conference cal.1 with Indiana Michigan Power Company (I&M) representatives regarding the ongoing steam generator (SG) tube inspection activities conducted during the 2012 outage at the Donald C. Cook Nuclear Plant, Unit 1. The NRC follows the results of the industry's SG inspections in order to maintain an awareness of the condition of the SGs and the types of tube degradation mechanisms that are active.

The enclosed documentation of the telephone call is provided to I&M for information. The information provided by I&M in support of the discussion (Agencywide Documents Access and Management System (ADAMS) Accession No. ML13189A222) is available to the public. Based on the information provided during the conference call, the NRC staff did not identify any issues that warranted additional follow-up action at this time. If there are any questions, please contact*

me at 301-415-4037.

Sincerely, IRAJ Thomas J. Wengert, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor licensing Office of Nuclear Reactor Regulation Docket No. 50-315

Enclosure:

Conference Call Summary cc w/encl: Distribution via ListServ DISTRIBUTION:

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