L-13-180, Supplemental Reply to Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1, License Renewal Application (TAC No. ME4640) and License Renewal Application Amendment 42

Supplemental Reply to Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1, License Renewal Application (TAC No. ME4640) and License Renewal Application Amendment 42

ML13144A079
Person / Time
Site:	Davis Besse
Issue date:	05/21/2013
From:	Lieb R FirstEnergy Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
L-13-180, TAC ME4640
Download: ML13144A079 (6)

Text

FENOCTM "5501 North State Route 2 FirstEnergyNuclear OperatingCompany Oak Harbor,Ohio 43449 Raymond A. Lieb 419-321-7676 Vice President,Nuclear Fax: 419-321-7582 May 21, 2013 L-1 3-180 10 CFR 54 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001

SUBJECT:

Davis-Besse Nuclear Power Station, Unit No. 1 Docket No. 50-346, License Number NPF-3 Supplemental Reply to Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1, License Renewal Application (TAC No. ME4640) and License Renewal Application Amendment 42 By letter dated August 27, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML102450565), FirstEnergy Nuclear Operating Company (FENOC) submitted an application pursuant to Title 10 of the Code of Federal Regulations, Part 54 for renewal of Operating License NPF-3 for the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse). By letter dated August 26, 2011 (ML11242A166), FENOC responded to Nuclear Regulatory Commission (NRC) request for additional information (RAI) B.2.22-6 regarding the installation of a core bore in the containment concrete floor to allow examination of the inaccessible inner surface of the steel containment vessel.

During development of the core bore project, FENOC determined that the proposed core bore location would result in high radiation doses to the workers involved in the project. FENOC is providing this supplemental reply to RAI B.2.22-6 to inform the NRC that a new core bore location has been selected that should provide better containment vessel degradation information and result in significantly lower radiation doses to the project workers.

The Attachment provides the FENOC supplemental reply to NRC RAI B.2.22-6. The NRC request is shown in bold text followed by the FENOC response. The Enclosure provides Amendment 42 to the Davis-Besse License Renewal Application.

Davis-Besse Nuclear Power Station, Unit No. 1 L-1 3-180 Page 2 There are no regulatory commitments contained in this letter. If there are any questions or if additional information is required, please contact Mr. Clifford I. Custer, Fleet License Renewal Project Manager, at 724-682-7139.

I declare under penalty of perjury that the foregoing is true and correct. Executed on May Z/_, 2013.

Sincerely, ay . Lieb

Attachment:

Supplemental Reply to Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse), License Renewal Application, Section B.2.22

Enclosure:

Amendment No. 42 to the Davis-Besse License Renewal Application cc: NRC DLR Project Manager NRC Region III Administrator cc: w/o Attachment or Enclosure NRC DLR Director NRR DORL Project Manager NRC Resident Inspector Utility Radiological Safety Board

Attachment L-1 3-180 Supplemental Reply to Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse),

License Renewal Application, Section B.2.22 Page 1 of 2 Supplemental Question RAI B.2.22-6 The Nuclear Regulatory Commission (NRC) initiated a telephone conference call with FirstEnergy Nuclear Operating Company (FENOC) on May 9, 2013, to discuss the proposed relocation of a core bore in the concrete floor of the Davis-Besse containment vessel. The core bore was originally described in the FENOC response to NRC request for additional information (RAI) B.2.22-6 and license renewal future Commitment 39, which were submitted by FENOC letter dated August 26, 2011 (ML11242A166). Following the discussion, FENOC stated they would submit a supplemental response to RAI B.2.22-6 to describe and justify the proposed new core bore location, and revise license renewal future Commitment 39 to include the containment vessel examination height above bottom dead center for the new location.

Supplemental RESPONSE RAI B.2.22-6 In the August 26, 2011 response to RAI B.2.22-6, second paragraph, FENOC stated the following:

"FENOC plans to locate the core bore below the reactor vessel where the Incore Tunnel opens through the primary shield wall into the area below the reactor vessel. That location is about eighteen feet from the containment vessel centerline. The lowest point of the containment vessel is about 30 inches lower than the elevation of the containment bottom head at the core bore location. The Incore Tunnel location was chosen because of the boron deposits that have been found in the Incore Tunnel."

During research and planning for the original proposed core bore (location 1), several concerns resulted in a proposal for a new core bore location (location 2). The reasons for relocating the core bore are as follows:

Location 2 is in the access hallway to the containment normal sump and provides better radiation shielding, which would significantly reduce the dose received by workers. Additional dose savings would be achieved during project execution since access to location 2 is much easier than the high dose rate path to location 1. The potential dose savings supports as low as is reasonably achievable (ALARA) dose reduction principles.

Attachment L-1 3-180 Page 2 of 2 Location 2 is closer to the center of the containment vessel than location 1.

Location 2 is near the containment vessel east-west centerline and approximately 8 feet east of the vessel north-south centerline. This location allows examination of a deeper section of the containment vessel, estimated from fabrication drawings to be less than approximately 10 inches vertical height above bottom dead center. Location 1, previously estimated to be about 30 inches vertical height above bottom dead center based on geographical interpolation, is now estimated from fabrication drawings to be less than approximately 24 inches vertical height above bottom dead center. A core bore at location 2 is significantly closer to the bottom dead center of the containment vessel than location 1, which addresses a concern about examining the containment vessel at a deeper location where borated water may pond. This ponding concern was raised by the Advisory Committee for Reactor Safeguards (ACRS) License Renewal Subcommittee during a September 19, 2012 meeting with FENOC [see transcript (ML122830433) page 22 and page 179].

Core bore location 1 was originally chosen because of boron deposits found in the Incore Tunnel near the site of location 1. FENOC planned to examine and test the removed location 1 concrete for potential aging effects from borated water, and plans to perform the same examination and testing described in Commitment 39 for concrete removed from location 2. Performing the core bore at location 2 does not reduce the effectiveness of the assessment of the containment structure and structural components. Rather, the new location provides for a better assessment of the containment vessel itself, the focus of license renewal future Commitment 39.

License renewal future Commitment 33, on the other hand, provides an assessment of the concrete exposed to borated water leakage. This commitment requires a sample of concrete from the south wall of the East/West Core Flood pipe tunnel, which has historically been exposed to leakage from the Refuel Canal. The sampling and testing required by Commitment 33 will address and bound the impacts of Refuel Canal leakage on concrete and reinforcing steel in containment. Therefore, the proposed change in core bore location does not reduce the effectiveness of the assessment of the containment structure and structural components.

LRA Table A-I, "Davis-Besse License Renewal Commitments," license renewal future Commitment 39, is revised to include the vertical height information for location 2 based on the information provided above.

See the Enclosure to this letter for the revision to the DBNPS LRA.

Enclosure A Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse)

Letter L-13-180 Amendment No. 42 to the Davis-Besse License Renewal Application Page 1 of 2 License Renewal Application Sections Affected Table A-1 The Enclosure identifies the change to the License Renewal Application (LRA) by Affected LRA Section, LRA Page No., and Affected Paragraph and Sentence. The count for the affected paragraph, sentence, bullet, etc. starts at the beginning of the affected Section or at the top of the affected page, as appropriate. Below each section the reason for the change is identified, and the sentence affected is printed in italics with deleted text fined-gt and added text underlined.

Enclosure A L-13-180 Page 2 of 2 Affected LRA Section LRA Page No. Affected Paragraph and Sentence Table A-1 Page A-69 Commitment No. 39 Based on the supplemental response to RAI B.2.22-6, license renewal future Commitment 39 in LRA Table A-i, "Davis-Besse License Renewal Commitments," is revised as follows:

Table A-I Davis-Besse License Renewal Commitments Item b m Commitment Im Implementation Source Related LRA Section No./

Number Schedule Cmet Comments 39 Address the potential for borated water degradation of the steel Phase 1 prior to FENOC Responses to containment vessel through the following actions: December 31, Letters NRC RAIs Access the inside surface of the embedded steel containment at 2014 L-11-153, B.2.22-2 from aad NRC Letter a vertical height no greaterthan 10 inches above bottom dead and L-11-237 dated center.A core bore will be completed by the end of 2014 Phase 2 prior to and April 5, 2011, (Phase 1). If necessary, a second core bore will be completed December 31, L-13-180 and by the end of 2020 (Phase 2). If there is evidence of the 2020 B.2.22-6 from presence of borated water in contact with the steel containment NRC Letter vessel, conduct non-destructive testing (NDT) to determine what dated effect, if any, the borated water has had on the steel July 27, 20 il, containment vessel. Based on the results of NDT, perform a study to determine the effect through the period of extended and operation of any identified loss of thickness in the steel Supplemental containment due to exposure to borated water. RAI B.2.22-6 from NRC telecon held on May 9, 2013