Letter Sequence Response to RAI |
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TAC:ME4640, Steam Generator Tube Integrity (Approved, Closed) |
Results
- Approval, Approval, Approval, Approval, Approval, Approval, Approval, Approval, Approval, Approval, Approval, Approval
Other: L-11-114, Drawing No. M-042B, Rev. 35, Sampling System Sh. 2 Local Grab Samples, L-11-131, Drawing No. LR-OS041A2, Revision 1, Operational Schematic Emergency Diesel Generator Systems., L-11-334, Reply to Request Additional Information for the Review of the License Renewal Application Amendment No. 21, L-12-337, Review of the Safety Evaluation Report with Open Items Related to the License Renewal, L-12-444, Submittal of Contractor Equivalent Margins Assessments for Reactor Vessel Welds (Nonproprietary Versions), L-12-456, Notification of Closure of Commitments Related to the Review of the License Renewal Application, L-13-257, Notification of Completion of a License Renewal Commitment Related to the Review of License Renewal Application TAC No. ME4640) and License Renewal Application Amendment No. 45), L-13-330, License Renewal Application Amendment No. 46 - Annual Update, L-13-341, Review of the Safety Evaluation Report Related to the License Renewal of Davis-Besse Nuclear Power Station, L-14-085, License Renewal Application (TAC No. ME4640) Amendment No. 48, L-14-206, License Renewal Application Amendment No. 50 - Annual Update, L-15-120, Notification of Completion of License Renewal Commitments Related to the Review of the Davis-Besse Nuclear Power Station, Unit No. 1, License Renewal Application and License Renewal Application Amendment No. 55, L-15-139, License Renewal Reactor Vessel Internals Inspection Plan, L-15-214, License Renewal Application Amendment No. 59 - Annual Update, L-15-309, License Renewal Application Amendment No. 60, L-15-310, C-CSS-099.20-069, Rev 0, Shield Building Laminar Cracking Limits., ML102450565, ML111050091, ML11110A089, ML11110A091, ML11110A092, ML11110A093, ML11110A094, ML11110A095, ML11110A105, ML11110A106, ML11110A107, ML11122A014, ML11126A017, ML11126A018, ML11126A019, ML11126A020, ML11126A021, ML11126A022, ML11126A023, ML11126A024, ML11126A025, ML11126A026, ML11126A032, ML11126A033, ML11126A034, ML11126A035, ML11126A036, ML11126A037, ML11126A038, ML11126A039, ML11126A040, ML11126A041, ML11126A042, ML11126A043... further results
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MONTHYEARML11126A0882008-01-12012 January 2008 Drawing No. LR-M041B, Revision 1, Piping & Instrument Diagram Primary Service Water System. Job Code 12501 Project stage: Other ML11126A0902008-01-15015 January 2008 Drawing No. LR-OS41A1, Revision 1, Operational Schematic Emergency Diesel Generator Systems. Project stage: Other L-11-131, Drawing No. LR-OS041A2, Revision 1, Operational Schematic Emergency Diesel Generator Systems.2008-01-15015 January 2008 Drawing No. LR-OS041A2, Revision 1, Operational Schematic Emergency Diesel Generator Systems. Project stage: Other ML11126A0682008-05-0505 May 2008 Drawing No. LR-M-037E, Revision 28, Piping & Instrument Diagram Clean Liquid Radioactive Waste System. Project stage: Other ML11126A0652008-08-0606 August 2008 Drawing No. LR-M036B, Revision 1, Piping & Instrument Diagram Component Cooling Water System. Project stage: Other ML11126A0592008-10-0909 October 2008 Drawing No. LR-M033A, Revision 1, Piping & Instrument Diagram High Pressure Injection. Project stage: Other ML11126A0632008-10-10010 October 2008 Drawing No. LR-M033B, Revision 1, Piping & Instrument Diagram Decay Heat Train 1. Project stage: Other ML11126A0702008-10-10010 October 2008 Drawing No. LR-M033C, Revision 1, Piping & Instrument Diagram Decay Heat Train 2. Project stage: Other ML11126A0742008-11-0606 November 2008 Drawing No. LR-M043, Revision 1, Piping & Instrument Diagram Auxiliary Building Chilled Water System. Project stage: Other ML11126A0832008-12-18018 December 2008 Drawing No. LR-M038C, Revision 2, Piping & Instrument Diagram Gaseous Radioactive Waste System. Job Code 12501 Project stage: Other ML11126A0712009-04-0707 April 2009 Drawing No. LR-M034, Revision 1, Piping & Instrument Diagram Emerg. Core Cooling System Ctmt. Spray & Core Flooding Systems. Project stage: Other ML11126A0892009-04-0707 April 2009 Drawing No. LR-OS002, Revision 1, Operational Schematic Makeup and Purification System. Project stage: Other ML1024505652010-08-27027 August 2010 License Renewal Application and Ohio Coastal Management Program Consistency Certification Project stage: Other ML1104500462011-02-17017 February 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station - Fire Protection Project stage: RAI ML11126A0792011-02-25025 February 2011 Drawing No. LR-M900A, Revision 0, Instrument Air System Piping Schematic. Project stage: Other ML1104205972011-02-28028 February 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station - Section 2.4 Project stage: RAI ML1106801722011-03-17017 March 2011 Request for Additional Information on the Reactor Vessel Surveillance Aging Management Program, Time-Limited Aging Analyses for Neutron Embrittlement of the Rv and Internals, and Other TLAAs for the Review of the Davis-Besse Nuclear Power S Project stage: RAI ML1107007322011-03-18018 March 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station-Section 2.2 & 2.3 Project stage: RAI L-11-078, Reply to Request for Additional Information for the Review of License Renewal Application (TAC ME4640) Amendment No. 12011-03-18018 March 2011 Reply to Request for Additional Information for the Review of License Renewal Application (TAC ME4640) Amendment No. 1 Project stage: Response to RAI ML11068A0002011-03-21021 March 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station - Section 4.7 (TAC Number ME4640) Project stage: RAI L-11-079, Reply to Request for Additional Information for the Review of the License Renewal Application2011-03-23023 March 2011 Reply to Request for Additional Information for the Review of the License Renewal Application Project stage: Response to RAI L-11-089, Reply to Request for Additional Information for the Review License Renewal Application2011-03-23023 March 2011 Reply to Request for Additional Information for the Review License Renewal Application Project stage: Response to RAI ML1108206242011-03-30030 March 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station-Section 2.1 (Tac No. ME4640) Project stage: RAI ML1109002952011-03-31031 March 2011 Safety Evaluation Report Related to the License Renewal of Salem Nuclear Generating Station Project stage: Approval ML1108204902011-04-0505 April 2011 Request for Additional Information for the Review of the Davis-Besse Nuclear Power Station - Batch 1 Project stage: RAI ML11110A0932011-04-15015 April 2011 Drawing No. M-037D, Rev. 21, Clean Liquid Radioactive Waste System Project stage: Other ML11110A1072011-04-15015 April 2011 Drawing No. M-045, Rev. 56, Chemical Addition Systems Project stage: Other ML11110A1062011-04-15015 April 2011 Drawing No. M-042C, Rev. 33, Sampling System Sh. 3 Project stage: Other ML11110A1052011-04-15015 April 2011 Drawing No. M-040A, Rev. 76, Reactor Coolant System Details Project stage: Other ML11110A0952011-04-15015 April 2011 Drawing No. M-039B, Rev. 18, Miscellaneous Liquid Radioactive Waste Project stage: Other ML11110A0942011-04-15015 April 2011 Drawing No. M-039A, Rev. 33, Miscellaneous Liquid Radioactive Waste Project stage: Other ML11110A0922011-04-15015 April 2011 Drawing No. M-037C, Rev. 30, Clean Liquid Radioactive Waste System Project stage: Other L-11-114, Drawing No. M-042B, Rev. 35, Sampling System Sh. 2 Local Grab Samples2011-04-15015 April 2011 Drawing No. M-042B, Rev. 35, Sampling System Sh. 2 Local Grab Samples Project stage: Other L-11-107, Reply to Request for Additional Information on Reactor Vessel Surveillance Aging Management Program & Time-Limited Aging Analyses for Neutron Embrittlement for Review of License Renewal Application & License Renewal Application...2011-04-15015 April 2011 Reply to Request for Additional Information on Reactor Vessel Surveillance Aging Management Program & Time-Limited Aging Analyses for Neutron Embrittlement for Review of License Renewal Application & License Renewal Application... Project stage: Response to RAI ML11110A0882011-04-15015 April 2011 Reply to Request for Additional Information for the Review of the License Renewal Application, Sections 2.2 & 2.3, License Renewal Application Amendment No. 3, and Revised License Renewal Project stage: Response to RAI ML11110A0912011-04-15015 April 2011 Drawing No. M-011, Rev. 61, Domestic Water System Project stage: Other ML11110A0892011-04-15015 April 2011 Drawing No. M-0060, Rev. 52, Auxiliary Feedwater System Project stage: Other ML1110500912011-04-19019 April 2011 Scoping and Screening Audit Report Regarding the Davis-Besse Nuclear Power Station License Renewal Application Project stage: Other L-11-115, Reply to Request for Additional Information for the Review of the License Renewal Application and License Renewal Application Amendment No. 42011-04-20020 April 2011 Reply to Request for Additional Information for the Review of the License Renewal Application and License Renewal Application Amendment No. 4 Project stage: Response to RAI ML1109807182011-04-20020 April 2011 Request for Additional Information for the Review of the Davis-Bessie Nuclear Power Station - Batch 2 Project stage: RAI ML11126A0362011-04-29029 April 2011 Drawing No. LR-M017D, Revision 1 Piping & Instrument Diagram, Steam Blackout Diesel Generator. Project stage: Other ML11126A0352011-04-29029 April 2011 Drawing No. LR-M017C, Revision 2, Piping & Instrument Diagram, Fuel Oil. Project stage: Other ML11126A0342011-04-29029 April 2011 Drawing No. LR-M017B, Revision 1, Piping & Instrument Diagram, Diesel Generators Air Start. Project stage: Other ML11126A0332011-04-29029 April 2011 Drawing No. LR-M016B, Revision 1, Piping & Instrument Diagram Station Fire Protection System Project stage: Other ML11126A0322011-04-29029 April 2011 Drawing No. LR-M016A, Revision 1, Piping & Instrument Diagram Station Fire Protection System Project stage: Other ML11126A0262011-04-29029 April 2011 Drawing No. LR-M010C, Revision 1, Piping & Instrument Diagram Make-up Water Treatment System Project stage: Other ML11126A0252011-04-29029 April 2011 Drawing No. LR-M010A, Revision 1, Piping & Instrument Diagram Make-Up Water Treatment System Project stage: Other ML11126A0242011-04-29029 April 2011 Drawing No. LR-M009B, Revision 1, Piping & Instrument Diagram Cooling Water System Project stage: Other ML11126A0192011-04-29029 April 2011 Drawing No. LR-M003A, Revision 1, Piping & Instrument Diagram Main Steam and Reheat System. Sheet 1 Project stage: Other ML11126A0452011-04-29029 April 2011 Drawing No. LR-M024H, Revision 1, Piping & Instrument Diagram, No. 2 Main and Auxiliary Turbine Driven Feed Pumps. Project stage: Other 2011-02-25
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Category:Letter
MONTHYEARML24249A1602024-09-0505 September 2024 Information Request to Support Upcoming Material Control and Accounting Inspection at Davis-Besse Nuclear Power Station L-24-188, Submittal of Quality Assurance Program Manual, Revision 302024-08-27027 August 2024 Submittal of Quality Assurance Program Manual, Revision 30 ML24239A3972024-08-23023 August 2024 Rssc Wire & Cable LLC Dba Marmon - Part 21 Final Notification - 57243-EN 57243 IR 05000346/20240052024-08-22022 August 2024 Updated Inspection Plan for Davis-Besse Nuclear Power Station (Report 05000346/2024005) IR 05000346/20240022024-08-0101 August 2024 Integrated Inspection Report 05000346/2024002 IR 05000346/20244012024-07-30030 July 2024 Security Baseline Inspection Report 05000346/2024401 ML24208A0962024-07-25025 July 2024 57243-EN 57243 - Rssc Wire & Cable LLC, Dba Marmon - Part 21 Notification L-24-032, Cycle 23 and Refueling Outage 23 Inservice Inspection Summary Report2024-07-15015 July 2024 Cycle 23 and Refueling Outage 23 Inservice Inspection Summary Report L-24-063, License Amendment Request to Remove the Table of Contents from the Technical Specifications2024-07-0808 July 2024 License Amendment Request to Remove the Table of Contents from the Technical Specifications L-24-024, Annual 10 CFR 50.46 Report of Changes to or Errors in Emergency Core Cooling System Evaluation Models2024-06-19019 June 2024 Annual 10 CFR 50.46 Report of Changes to or Errors in Emergency Core Cooling System Evaluation Models L-23-214, Submittal of Relief Request for Impractical American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements2024-06-0505 June 2024 Submittal of Relief Request for Impractical American Society of Mechanical Engineers Boiler and Pressure Vessel Code Section XI Examination Requirements L-24-019, Unit No.1 - Report of Facility Changes, Tests, and Experiments2024-05-22022 May 2024 Unit No.1 - Report of Facility Changes, Tests, and Experiments ML24142A3532024-05-21021 May 2024 Station—Information Request to Support the NRC Annual Baseline Emergency Action Level and Emergency Plan Changes Inspection L-24-111, Response to Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations2024-05-15015 May 2024 Response to Regulatory Issue Summary 2024-01, Preparation and Scheduling of Operator Licensing Examinations L-24-072, Combined Annual Radiological Environmental Operating Report and Radioactive Effluent Release Report - 20232024-05-15015 May 2024 Combined Annual Radiological Environmental Operating Report and Radioactive Effluent Release Report - 2023 L-24-031, Unit No.1 - Steam Generator Tube Circumferential Crack Report - Spring 2024 Refueling Outage2024-05-14014 May 2024 Unit No.1 - Steam Generator Tube Circumferential Crack Report - Spring 2024 Refueling Outage IR 05000346/20240012024-05-0303 May 2024 Integrated Inspection Report 05000346/2024001 L-24-069, Occupational Radiation Exposure Report for Year 20232024-04-30030 April 2024 Occupational Radiation Exposure Report for Year 2023 L-24-018, Submittal of Core Operating Limits Report, Cycle 24, Revision 02024-04-16016 April 2024 Submittal of Core Operating Limits Report, Cycle 24, Revision 0 ML24089A2582024-04-0101 April 2024 Request for Information for the NRC Quuadrennial Comprehensive Engineering Team Inspection: Inspection Report 05000346/2024010 L-24-013, Annual Notification of Property Insurance Coverage2024-03-26026 March 2024 Annual Notification of Property Insurance Coverage ML24036A3472024-03-0707 March 2024 Exemption from Select Requirements of 10 CFR Part 73 (EPID L-2023-LLE-0076 (Security Notifications, Reports, and Recordkeeping and Suspicious Activity Reporting)) ML24057A0752024-03-0101 March 2024 the Associated Independent Spent Fuel Storage Installations IR 05000346/20230062024-02-28028 February 2024 Re-Issue Annual Assessment Letter for Davis-Besse Nuclear Power Station (Report 05000346/2023006) ML24057A3362024-02-28028 February 2024 Annual Assessment Letter for Davis-Besse Nuclear Power Station (Report 05000346/2023006) CP-202300502, Notice of Planned Closing of Transaction and Provision of Documents to Satisfy Order Conditions2024-02-23023 February 2024 Notice of Planned Closing of Transaction and Provision of Documents to Satisfy Order Conditions L-24-050, Retrospective Premium Guarantee2024-02-22022 February 2024 Retrospective Premium Guarantee IR 05000346/20243012024-02-0202 February 2024 NRC Initial License Examination Report 05000346/2024301 IR 05000346/20230042024-01-31031 January 2024 Integrated Inspection Report 05000346/2023004 ML23313A1352024-01-17017 January 2024 Authorization and Safety Evaluation for Alternative Request RP 5 for the Fifth 10 Year Interval Inservice Testing Program ML23353A1192023-12-19019 December 2023 Operator Licensing Examination Approval Davis Besse Nuclear Power Station, January 2024 L-23-260, Corrections to the 2022 Combined Annual Radiological Environmental Operating Report and Radioactive Effluent Release Report for the Davis-Besse Nuclear Power Station2023-12-0707 December 2023 Corrections to the 2022 Combined Annual Radiological Environmental Operating Report and Radioactive Effluent Release Report for the Davis-Besse Nuclear Power Station L-23-243, Independent Spent Fuel Storage Installation - Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-0606 December 2023 Independent Spent Fuel Storage Installation - Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation ML23338A3172023-12-0606 December 2023 Notification of NRC Baseline Inspection and Request for Information; Inspection Report 05000346/2024001 IR 05000346/20234032023-11-0202 November 2023 Security Baseline Inspection Report 05000346/2023403 ML23293A0612023-11-0101 November 2023 Letter to the Honorable Marcy Kaptur, from Chair Hanson Responds to Letter Regarding Follow Up on Concerns Raised by Union Representatives During the June Visit to the Davis-Besse Nuclear Power Plant ML24045A0322023-10-26026 October 2023 L-23-221 Proposed Exam Submittal Cover Letter L-23-215, Changes to Emergency Plan2023-10-19019 October 2023 Changes to Emergency Plan ML23237B4222023-09-28028 September 2023 Energy Harbor Nuclear Corp. - Vistra Operations Company LLC - Letter Regarding Order Approving Transfer of Licenses and Draft Conforming License Amendments ML23269A1242023-09-27027 September 2023 Request for Withholding Information from Public Disclosure IR 05000346/20234012023-09-13013 September 2023 Security Baseline Inspection Report 05000346/2023401 (Public) L-23-205, Supplement to Application for Order Consenting to Transfer of Licenses and Conforming License Amendments2023-09-12012 September 2023 Supplement to Application for Order Consenting to Transfer of Licenses and Conforming License Amendments L-23-172, Quality Assurance Program Manual2023-08-31031 August 2023 Quality Assurance Program Manual IR 05000346/20230112023-08-30030 August 2023 Biennial Problem Identification and Resolution Inspection Report 05000346/2023011 ML23129A1722023-08-25025 August 2023 Request for Withholding Information from Public Disclosure for Beaver Valley Power Station, Units 1 and 2; Davis Besse Nuclear Power Station, Unit 1; and Perry Nuclear Power Plant, Unit 1 IR 05000346/20230052023-08-24024 August 2023 Updated Inspection Plan for Davis-Besse Nuclear Power Station (Report 05000346/2023005) L-23-188, Energy Harbor Nuclear Corp., Supplement to Application for Order Consenting to Transfer of Licenses and Conforming License Amendments2023-08-0707 August 2023 Energy Harbor Nuclear Corp., Supplement to Application for Order Consenting to Transfer of Licenses and Conforming License Amendments IR 05000346/20230502023-08-0303 August 2023 Special Inspection Report 05000346/2023050 L-23-175, Submittal of Fifth Ten Year Inservice Testing Program2023-08-0101 August 2023 Submittal of Fifth Ten Year Inservice Testing Program IR 05000346/20230902023-08-0101 August 2023 EA-23-002 Davis-Besse Nuclear Power Station - NRC Inspection Report No. 05000346/2023090 (Public) 2024-09-05
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Text
FE NOC FirstEnergy Nuclear Operating Company October 28, 2014 L-14-354 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 Davis-Besse Nuclear Power Station 5501 N. State Route 2 Oak Harbor, Ohio 43449 10 CFR 54 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) By letter dated August 27, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML 102450565), 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 September 29, 2014 (ML 14258A285), the Nuclear Regulatory Commission (NRC) requested additional information to complete its review of the License Renewal Application (LRA). The Attachment provides the FENOC reply to the NRC request for additional information.
The NRC request is shown in bold text followed by the FENOC response.
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 October 2014. Sincerely, Director, Site Operations Davis-Besse Nuclear Power Station, Unit No. 1 L-14-354 Page 2
Attachment:
Reply to Requests for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse), License Renewal Application (LRA), Section B.2.43 cc: NRC DLR Project Manager NRC Region 111 Administrator cc: w/o Attachment NRC DLR Director NRR DORL Project Manager NRC Resident Inspector Utility Radiological Safety Board Attachment L-14-354 Reply to Requests for Additional Information for the Review of the Davis-Besse Nuclear Power Station, Unit No. 1 (Davis-Besse), License Renewal Application (LRA), Section B.2.43 Page 1 of 7 Question RAI B.2.43-5 (follow-up)
Background:
FENOC's response to RAI B.2.43-4 by letter dated July 3, 2014 (ADAMS Accession No. ML 14184B184), states in part: Due to the plant-specific operating experience described in the request, above, the minimum number of Shield Building monitoring bores currently managed under the FENOC Corrective Action Program is being changed to 23. Three monitoring bores will be used to aid in identifying changes in the limits of cracking in areas with previously identified crack propagation.
New core bores will be installed as required during each inspection cycle to bound crack limits. The "Operating Experience" program element of LRA Section B.2.43, "Shield Building Monitoring Program," revised by letter dated July 3, 2014 in response to RAI B.2.43-4, states in part, "This re-inspection also identified 8 conditions where the laminar cracking conditions were determined to have undergone a discernable change." Issue: In response to RAI B.2.43-4, the basis or criteria for selecting three (3) of the eight (8) core bore holes, with discernable change in laminar cracking conditions, in the sample for subsequent consecutive inspections was not fully or clearly described.
Request: 1) Provide additional discussion and detail on the technical rationale or criteria used to justify the selection of additional core bore holes for future examination.
- 2) Provide, with the basis, the minimum number and/or time period of subsequent consecutive inspections for which core bore holes with identified crack propagation will be inspected following discovery before they may be removed from the representative sample. The response should include a discussion of the consideration, if any, given the core bore hole inspection Attachment L-14-354 Page 2of7 intervals and the schedule proposed in the Shield Building Monitoring Program. RESPONSE RAI B.2.3-5 (follow-up)
- 1) The selection of additional core bores for future examination of the cracking identified within the Davis-Besse Shield Building will be based on the extent and direction of propagation of laminar cracking in the structure.
FirstEnergy Nuclear Operating Company (FENOC) currently knows the size and extent of the original pre-existing sub-surface crack, and the cause and rate of crack propagation due to ice-wedging.
FENOC is monitoring the crack size, shape and progression by use of 23 strategically-selected core bores, 3 of which were chosen to monitor the leading edge of crack propagation; these 23 bores are representative of the remaining cracked areas. If crack planar propagation passes completely through 1 of the 3 leading edge core bores, then a new leading edge core bore will be added adjacent to that bore to maintain at least 3 leading edge monitoring bores. The condition of cracking identified within the Davis-Besse Shield Building is a phenomenon of laminar cracking oriented in the plane of the outside face rebar for the Shield Building, caused by a single event in 1978. Crack perimeters were identified to be slowly expanding or propagating during routine long term monitoring inspections in 2013. This propagation was identified within areas overlaid by the building architectural shoulders.
It has been determined through causal analysis that the crack propagation is a result of "ice wedging".
Concrete crack growth by ice wedging, by definition, requires a previously existing crack, the presence of water and a freezing cycle, resulting in the extension of the crack. The entire shield building was mapped with Impulse Response Testing and validated by over 80 core bores in 2011-12. Therefore, the location of the existing sub-surface crack is understood.
During the 2013 monitoring of core bores for the Shield Building laminar cracking condition, "new" cracking was identified in 8 bores. As part of the extent of condition investigation, FENOC conducted informational Impulse Response mapping at 5 locations (approximately 2200 square feet) for overall perimeter identification, and examined all 80 existing bore locations.
The discovery of changes in the condition of the structure validates that visual bore monitoring is an effective means of identifying changes in the structure.
In order to understand the changes, the features of the 8 bores with changes were assessed and divided into two categories.
The first category (Category
- 1) is where the leading edge of an existing crack propagated into previously un-cracked concrete (perimeter expansion -5 bores). The second category (Category
- 2) is where changes were identified in a previously cracked bore where planar propagation was Attachment L-14-354 Page 3of7 not identified (3 bores). A crack offshoot developing in a bore is representative of the changes identified in these 3 locations.
Following analysis of the 5 Category 1 bores, it was identified that 2 bores are already within the population of the originally proposed 20 bores selected for long term monitoring under the Shield Building Monitoring Program. Therefore the remaining 3 bores are added to the program for monitoring.
Category 2 bores were not incorporated into the monitoring program since they do not provide information related to identifying the leading edge (perimeter) of the crack. The existing monitoring program includes a population of bores within the area of cracking such that determination of changes to the cracked condition can be identified.
Of the 23 bores identified for long term monitoring, a subset of 3 locations where the crack perimeter has been determined to be expanding will also be monitored such that planar limits of the crack are monitored and bounded. This selection of 3 locations is representative of the 5 Category 1 bores with considerations to the fact that 2 of the 5 bores intersect the same leading edge (bores are drilled at approximately the same elevation, approx. 2' horizontally offset from each other), as well as personnel safety access limitations for 1 bore near the start-up transformer.
The aging management program will now routinely examine 23 bores at various locations around the structure.
The visual inspection method has proven to be effective at identifying small changes in the laminar cracking, and the population of 20 bores for monitoring at various elevations is representative of the initial driven laminar cracking condition.
The addition of the 3 bores for ongoing monitoring at the leading edge of planar propagation combined with the 20 existing monitoring bores is adequate to track and manage the propagation phenomenon, and is representative of the remaining cracked areas. If crack planar propagation passes completely through any of the 3 leading edge core bores, then a new leading edge core bore will be added adjacent to that bore to maintain at least 3 leading edge monitoring bores. 2) There is no minimum number and/or time period of subsequent consecutive inspections for which core bore holes with identified crack propagation will be inspected following discovery before they may be removed from the representative sample. FENOC intends to perform inspections of the 23 monitoring bores throughout the period of extended operation.
A bore hole added to the inspection scope for the purposes of monitoring laminar cracking limits would be removed from scope if it has been cracked 360 degrees around and can no longer bound cracking limits. Prior to removal from the scope of inspection, a new leading edge core bore would be installed adjacent to the bore being removed in order to maintain the population of 3 leading edge core bores for monitoring crack propagation.
Attachment L-14-354 Page 4of7 Based on the FENOC response to NRC requests for additional information (RAls) on Shield Building cracking submitted by letter dated July 3, 2014 (ADAMS Accession Number ML 14184B184), the frequency of internal visual inspection for the 23 monitoring bores is annual inspections for a minimum of 4 years starting in 2015. For the Shield Building Monitoring Program, following acceptable results of the one-year interval inspections, the interval will be changed to a two-year interval in 2019, to a maximum four-year interval after the 2026 inspections.
These inspection intervals will be evaluated for effectiveness by the Shield Building Monitoring Program. Should there be an identified change to the cause of the condition, significant change to the rate of crack growth, or a condition adverse to the bounding nature of the design basis documentation, modifications to the Shield Building Monitoring Program will be determined using the FENOC Corrective Action Program. As noted in the Shield Building Monitoring Program, Sections 2.4.b and 2.6.b, bore holes are examined for changes in crack width. Therefore, even if a bore hole is cracked 360 degrees around and no longer able to define planar limits, any previously identified changes to width will have been entered into the Corrective Action Program, and that information will be used in the decision-making process to determine whether changes are required to the inspection schedule (e.g., increase inspection frequency) or parameters monitored (e.g., increase the number of core bores monitored).
Question RAI B.2.43-6 (follow-up)
Background:
LRA Section B.2.43, updated by letters dated November 20, 2012 and July 3, 2014, describes the plant-specific Shield Building Monitoring Program. This aging management program (AMP) includes under its scope the steel reinforcement bar (rebar) and concrete of the shield building wall and the exterior concrete coatings on the shield building.
The "Program Description" and program element "Parameters Monitored or Inspected" state that the program will monitor rebar for loss of material due to corrosion by visual inspection of the surface condition of rebar, when exposed. The "Operating Experience" program element of LRA Section B.2.43, revised by RAI B.2.43-4 response letter dated July 3, 2014 (ADAMS Accession No. ML 14184B184), identified conditions involving propagation of the shield building laminar cracks during a 2013 baseline inspection, and states in part that:
Attachment L-14-354 Page 5of7 This re-inspection also identified 8 conditions where the laminar cracking conditions were determined to have undergone a discernable change. The cracking propagation was determined to be a result of ice-wedging (freezing water at a pre-existing crack leading edge). This condition requires water, freezing temperatures and pre-existing cracks. Because the Shield Building has been coated it contains a finite amount of water. It is not practical to remove the water in an accelerated manner given the cumulative magnitude of leading crack edges and transportability of water. It is also not practical to remove the existing cracks or prevent freezing temperatures.
The response to RAI B.2.43-4 did not identify any changes to the Shield Building Monitoring Program with regard to monitoring of the rebar for corrosion but documented operating experience of the presence of water within the pre-existing cracks which under freezing temperatures may cause the cracks to propagate.
Issue: The Shield Building Monitoring Program monitors rebar for corrosion by visual inspection, on an opportunistic basis, only when exposed for some undefined reason. The presence of water and air trapped within the existing potentially propagating laminar cracks of the coated shield building wall increases the potential for corrosion of the adjacent rebar layers. The staff also noted in LRA Section 3.5.2.2.1.1 that the groundwater chemistry at the Davis-Besse site is considered to be aggressive (i.e., chlorides
= 2,870 ppm (max) and sulfates = 1, 700 ppm (max)) which may also be indicative that the shield building is or has been exposed to potentially aggressive (high chloride content) air-outdoor environment that favors potential for rebar corrosion.
Given the above specific conditions and operating experience, the staff needs additional technical justification and basis regarding the AMP's implementation of opportunistic inspections to monitor aging effects in the rebar located near the laminar cracking.
Request: Considering the plant-specific conditions of the shield building wall associated with existing laminar cracking that may propagate; presence of trapped water and air in the laminar cracks; and potentially aggressive environmental conditions; explain, with sufficient technical detail and basis, the following:
- 1) How opportunistic inspection of rebar when exposed will adequately manage potential aging effects of rebar corrosion for rebar layers located near laminar cracking, or Attachment L-14-354 Page 6of7 2) Any modifications or enhancements that will be made to the Shield Building Monitoring Program or any other applicable AMP to address the staff's concern regarding the implementation of opportunistic inspection of rebar when exposed to manage potential aging effects of rebar corrosion for rebar layers located near laminar cracking.
RESPONSE RAI B.2.43-6 (follow-up)
- 1) Opportunistic inspection of rebar when exposed will adequately manage potential aging effects of rebar corrosion for rebar layers located near laminar cracking.
FirstEnergy Nuclear Operating Company (FENOC) visually inspected rebar in areas of laminar cracking at the construction opening during the 17th Mid-Cycle Outage in October and November, 2011 (i.e., after greater than 30 years of operation), and determined that the presence of cracking itself has not resulted in unacceptable rebar material loss or corrosion.
The presence of potentially aggressive environmental conditions (groundwater) is not considered a related condition associated with the laminar cracking condition.
Impulse-Response mapping completed on exterior portions of the Shield Building during the summer of 2012 did not identify laminar cracking below elevation 615'. The grade elevation at site is 584' -0" (i.e., more than 31 feet below the laminar cracking), with groundwater below that elevation.
Therefore, postulated scenarios of interaction between groundwater and the laminar cracking condition are not considered credible.
As a corrective action for the identification of laminar cracking, FENOC applied an exterior coating to the Shield Building during 2012. This coating, as documented in American Concrete Institute (ACI) 222R-85, "Corrosion of Metals in Concrete," Chapter 5, is a means to limit the availability of oxygen and moisture that are required to sustain a corrosive environment.
Therefore, despite the identification of water within the concrete, FENOC has limited the introduction of additional oxygen and moisture such that the postulated corrosion rate of rebar is expected to remain minimal, with a decreasing trend. With respect to the water found in core bores, FENOC completed a causal investigation for the laminar cracking propagation condition.
This causal analysis included chemical analysis of the water. It was concluded that the water constituents were "typical of water that was in contact with the concrete for a period of time." Water samples collected exhibited high pH values (average greater than 10). It is therefore documented that the " ... water itself with salt and high pH is not conducive to generate corrosion in the rebar." Given the supporting evidence that the alkali environment within the concrete is inhibiting corrosion, and the mitigating nature of the coating, FENOC has elected to Attachment L-14-354 Page 7of7 conduct opportunistic inspections of the rebar. Corrosion of rebar would result in visual indications such as staining, cracking and spalling on the exterior of the structure or in core bores that are located near rebar. These indications are aspects monitored under the Structures Monitoring Program to adequately manage aging of the structure, inclusive of potential rebar corrosion.
- 2) Based on Response 1, above, no modifications or enhancements to Davis-Besse License Renewal Aging Management Programs are necessary.