ML12024A276

Summary of Telephone Conference Call Held on October 31, 2011, Between the U.S. Nuclear Regulatory Commission and Firstentergy Nuclear Operating Company Concerning Request for Additional Information Pertaining to the 10 31 2011 DB NRC Telec

ML12024A276
Person / Time
Site:	Davis Besse
Issue date:	02/21/2012
From:	Cuadradodejesus S License Renewal Projects Branch 1
To:
CuadradoDeJesus S
References
TAC ME4640
Download: ML12024A276 (7)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 February 21, 2012 LICENSEE: FirstEnergy Nuclear Operating Company FACILITY: Davis-Besse Nuclear Power Station

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 31, 2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND FIRSTENERGY NUCLEAR OPERATING COMPANY, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE DAVIS-BESSE NUCLEAR POWER STATION, LICENSE RENEWAL APPLICATION (TAC. NO. ME4640)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of FirstEnergy Nuclear Operating Company (FENOC or the applicant) held a telephone conference call on October 31.2011, to discuss and clanfy the applicant's responses to the staff's requests for additional information (RAls) concerning the Davis-Besse license renewal application provides a listing of the participants and Enclosure 2 contains a description of the staff concerns discussed with the applicant A brief description on the status of the items is also included.

Tlje applicant had an opportunity to comment on this summary.

Docket No. 50-346

Enclosures:

1. List of Participants

2. List of Requests for Additional Information cc w/encls' Listserv

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SUMMARY

OF TELEPHONE CONFERENCE CALL DAVIS-BESSE LICENSE RENEWAL APPLICATION LIST OF PARTICIPANTS OCTOBER 31,2011 PARTICIPANTS AFFILIATIONS Samuel Cuadrado de Jesus U.S. Nuclear Regulatory Commission (NRC)

Christopher Hunt NRC Seung Min NRC Kenneth Karwoski NRC Todd Mintz Center for Nuclear Waste Regulatory Analyses Cliff Custer FirstEnergy Nuclear Operating Company (FENOC)

Steve Dort FENOC Larry Hinkle FENOC Luke Twarek FENOC ENCLOSURE 1

SUMMARY

OF TELEPHONE CONFERENCE CALL DAVIS-BESSE LICENSE RENEWAL APPLICATION OCTOBER 31,2011 The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of FirstEnergy Nuclear Operating Company (FENOC or the applicant) held a telephone conference call on October 31, 2011. The purpose of the telephone conference call was to discuss and clarify a draft request for additional information (RAI) 3.1.2.2.16-2 in relation to the FENOC response to RAI 3.1.2.2.16-1 submitted under FENOC letter dated October 21, 2011.

Response to RAI 3.1.2.2.16-1 Previous to the telephone conference call the following draft RAI was provided to the applicant:

Draft RAI 3.1.2.2.16-2

Background:

By letter dated October 21, 2011, the applicant responded to RAI 3.1.2.2.16-1, which addresses a need for the aging management of cracking due to primary water stress corrosion cracking (PWSCC) of the steam generator (SG) tube-to-tubesheet welds. In its response, the applicant stated that cracking due to PWSCC will be managed for the SG tube-to-tubesheet welds (Alloy 600) by a combination of the PWR Water Chemistry Program and the Steam Generator Tube Integrity Program. The applicant also stated that the Steam Generator Tube Integrity Program will be enhanced to include enhanced visual (EVT-1 or equivalent) examinations to monitor for cracking of the SG tube-to-tubesheet welds. The applicant further indicated that welds included in the inspection sample will be scheduled for examination in each 10-year period that occurs during the period of extended operation and unacceptable inspection findings will be evaluated by the Corrective Action Program using criteria in accordance with Section XI of the ASIVlE Code.

In addition, the applicant indicated that a review of Davis-Besse operating experience has not identified any instances of cracking of the SG tube-to-tubesheet welds (Alloy 600): therefore, the weld inspection sample size will include 20 percent of the subject weld population or a maximum of 25, whichever is less. The applicant stated that in this case the maximum of 25 applies since the weld population for the two SGs is greater than 60,000. The applicant also indicated that if the SGs are replaced in the future with a design such that the tube-to-tubesheet welds are fabricated of Alloy 690 TT material, the examinations will no longer be required.

Issue:

In its review, the staff found a need to clarify whether or not the "Alloy 690 TT material,"

which refers to a potential material for future SG welds, means Alloy 690 n tubes with Alloy 690 type weld material (e.g., Alloy 52). The staff also noted that it is not so clear ENCLOSURE 2

-2 not the EVT-1 inspection is capable of detecting cracking in the tube-to-tubesheet weld.

The staff also requests that the applicant discuss the extent to which the routine SG tube inspections, using bobbin coil or rotating coil examinations, can detect cracking of the tube-to-tubesheet welds.

The staff also found a need to clarify why a sample size of only 25 is adequate to monitor for the cracking of the SG tube-to-tubesheet welds in view of the following considerations: (1) potential variabilities exist in the weld chemistry, environment and stresses in the approximately 60,000 welds, (2) Alloy 600 is susceptible to PWSCC, (3) the applicant's SG tubes (Alloy 600) have experienced cracking due to PWSCC, indicating that the degradation mechanism (PWSCC) exists for the SG tubes, and (4) the applicant's program has not implemented any inspection intended to detect cracking in the tube-to-tubesheet welds.

Request:

1. The applicant indicated that examinations are no longer required if the SGs are replaced in the future with a design such that the tube-to-tubesheet welds are fabricated with Alloy 690 TT material. Provide information to clarify whether or not the "Alloy 690 TT material" means Alloy 690 TT tubes with Alloy 690 type welds (e.g., Alloy 52). If not, discuss why inspections are not necessary to manage cracking due to PWSCC of the replacement SG welds.

2. It is not clear that Section XI of the ASME Code has acceptance criteria for these SG tube-to-tubesheet welds. Discuss what acceptance criteria will be used to evaluate the indications found in the inspections.

3. Provide information to demonstrate the EVT-1 inspection is capable of detecting cracking in the tube-to-tubesheet welds. In addition, discuss the extent, to which the routine SG tube inspections, using bobbin coil or rotating coil examinations, can detect cracking of the tube-to-tubesheet welds.

4. Provide justification as to why a sample size of only 25 is adequate to monitor for the cracking of the SG tube-to-tubesheet welds in view of the following considerations:

(i) potential variabilities exist in the weld chemistry, environment and stresses in the approximately 60,000 welds, (ii) Alloy 600 tubes are susceptible to PWSCC, (iii) the applicant's Alloy 600 tubes have experienced cracking due to PWSCC, indicating that the degradation mechanism (PWSCC) exists for the SG tubes, and (iv) the applicant's program has not implemented any inspection intended to detect cracking in the tube-to-tubesheet welds.

-3 Discussion:

The staff and the applicant discussed each of the four requests of draft RAI 3.1.2.2.16-2 as follows:

Request 1 The staff requested clarification as to whether or not the "Alloy 690 TT material" means Alloy 690 IT tubes with Alloy 690 type welds (Ex. Alloy 52).

The applicant responded that the tubes and the tubesheet cladding of the replacement SGs will be fabricated with Alloy 690 TT material. In addition, the tube-to-tubesheet welds will not use weld filler material (I.e., autogenous welds).

The staff stated that it will revise draft RAI 3.1.2.2.16-2 accordingly.

Request 2 The applicant and the staff agreed that Section XI of the ASME Code does not have acceptance criteria for the SG tube-to-tubesheet weld examinations. One possibility is to evaluate the largest crack size that can be tolerated and set acceptance criteria accordingly.

Request 3 The staff indicated that the tube-to-tubesheet weld EVT-1 examination needs to be able to demonstrate that it is capable of detecting cracking due to PWSCC. The staff also stated that EVT-1 could be supplemented with the routine tube inspections (eddy-current testing) if EVT-1 confidence is in question.

Request 4 The staff stated that it does not believe that a sample size of only 25 is adequate to monitor for the cracking of the SG tube-to-tubesheet welds.

After discussions between the staff and the applicant, it was agreed that the inspections should focus on the hot leg end of the SG and that an appropriate sample size would be 20 percent.

The applicant raised the issue that when the replacement SG are installed, assuming the subject welds are Alloy 690 TT material, that cracking due to PWSCC would be managed by the PWR Water Chemistry Program and the examinations would no longer be required.

The staff agreed.

ACTION: The staff will issue RAI 3.1.2.2.16-2.

LICENSEE: FirstEnergy Nuclear Operating Company FACILITY: Davis-Besse Nuclear Power Station

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 31,2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND FIRSTENERGY NUCLEAR OPERATING COMPANY, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE DAVIS-BESSE NUCLEAR POWER STATION, LICENSE RENEWAL APPLICATION (TAC. NO. ME4640)

The U.S. Nuclear Regulatory Commission (NRC or the staff) and representatives of FirstEnergy Nuclear Operating Company (FENOC or the applicant) held a telephone conference call on October 31, 2011, to discuss and clarify the applicant's responses to the staff's requests for additional information (RAls) concerning the Davis-Besse license renewal application. provides a listing of the participants and Enclosure 2 contains a description of the staff concerns discussed with the applicant. A brief description on the status of the items is a/so included.

The applicant had an opportunity to comment on this summary.

IRA!

Samuel Cuadrado de Jeas, Project Manager Projects Branch 1 Division of License Renewal Office of Nuclear Reactor Regulation Docket No. 50-346

Enclosures:

1. List of Participants

2. List of Requests for Additional Information cc w/encls: Listserv DISTRIBUTION: See next page ADAMS Accession No ... ML12024a276 OFFICE LA:RPB1 :DLR PM:RPB1 :DLR BC:RPB1 :DLR NAME YEdmonds SCuadrado de Jeas DMorey DATE 02/13/12 02/15/12 02/21 112 OFFICIAL RECORD COpy

Memorandum to FirstEnergy Nuclear Operating Company from Samuel Cuadrado de JesS dated February 21,2012

SUMMARY

OF TELEPHONE CONFERENCE CALL HELD ON OCTOBER 31,2011, BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND FIRSTENERGY NUCLEAR OPERATING COMPANY, CONCERNING REQUESTS FOR ADDITIONAL INFORMATION PERTAINING TO THE DAVIS-BESSE NUCLEAR POWER STATION, LICENSE RENEWAL APPLICATION (TAC. NO. ME4640)

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