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Category:Letter type:DCL
MONTHYEARDCL-24-010, Nuclear Material Transaction Report for New Fuel2024-01-29029 January 2024 Nuclear Material Transaction Report for New Fuel DCL-24-009, Nuclear Material Transaction Report for New Fuel2024-01-17017 January 2024 Nuclear Material Transaction Report for New Fuel DCL-24-008, Schedule Considerations for Review of the DCPP License Renewal Application2024-01-17017 January 2024 Schedule Considerations for Review of the DCPP License Renewal Application DCL-24-004, Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2024-01-15015 January 2024 Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b DCL-23-129, Nuclear Material Transaction Report for New Fuel2023-12-27027 December 2023 Nuclear Material Transaction Report for New Fuel DCL-23-122, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-14014 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation DCL-23-128, Emergency Plan Update2023-12-13013 December 2023 Emergency Plan Update DCL-23-125, Core Operating Limits Report for Unit 1 Cycle 252023-12-0606 December 2023 Core Operating Limits Report for Unit 1 Cycle 25 DCL-23-121, Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System2023-11-16016 November 2023 Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System DCL-23-120, License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System2023-11-14014 November 2023 License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System DCL-23-118, License Renewal Application2023-11-0707 November 2023 License Renewal Application DCL-2023-520, Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP)2023-10-19019 October 2023 Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP) DCL-23-103, Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System2023-10-13013 October 2023 Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System DCL-23-092, Material Status Report for the Period Ending August 31, 20232023-09-28028 September 2023 Material Status Report for the Period Ending August 31, 2023 DCL-23-077, License Amendment Request 23-02 Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors2023-09-27027 September 2023 License Amendment Request 23-02 Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors DCL-23-083, Upcoming Meeting with Nuclear Security and Incident Response Staff2023-09-13013 September 2023 Upcoming Meeting with Nuclear Security and Incident Response Staff DCL-23-078, Nuclear Material Transaction Report for New Fuel2023-09-0606 September 2023 Nuclear Material Transaction Report for New Fuel DCL-23-070, Withdrawal of Request Regarding Senior Reactor Operator License Application2023-08-16016 August 2023 Withdrawal of Request Regarding Senior Reactor Operator License Application DCL-23-068, Nuclear Material Transaction Report for New Fuel2023-08-0909 August 2023 Nuclear Material Transaction Report for New Fuel DCL-23-066, Nuclear Material Transaction Report for New Fuel2023-08-0303 August 2023 Nuclear Material Transaction Report for New Fuel DCL-23-065, Letter DCL-23-065 Request That Exam Material Be Withheld from Public Disclosure2023-07-27027 July 2023 Letter DCL-23-065 Request That Exam Material Be Withheld from Public Disclosure DCL-23-064, Nuclear Material Transaction Report for New Fuel2023-07-26026 July 2023 Nuclear Material Transaction Report for New Fuel DCL-23-054, License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2023-07-13013 July 2023 License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b DCL-23-055, Nuclear Material Transaction Report for New Fuel2023-07-0606 July 2023 Nuclear Material Transaction Report for New Fuel DCL-23-042, Independent Spent Fuel Storage Installation, Submittal of Quality Assurance Program Description, Revision 02023-05-24024 May 2023 Independent Spent Fuel Storage Installation, Submittal of Quality Assurance Program Description, Revision 0 DCL-23-032, Independent Spent Fuel Storage Installation Docket No. 72-27, Materials License Number SNM-2514 Humboldt Bay Independent Spent Fuel Storage Installation - NRC Requested Notification of Withdrawal from Voluntary Program2023-05-22022 May 2023 Independent Spent Fuel Storage Installation Docket No. 72-27, Materials License Number SNM-2514 Humboldt Bay Independent Spent Fuel Storage Installation - NRC Requested Notification of Withdrawal from Voluntary Program DCL-23-041, 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 20222023-05-22022 May 2023 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 2022 DCL-23-038, Revision to the Unit 1 Reactor Vessel Material Surveillance Program Withdrawal Schedule2023-05-15015 May 2023 Revision to the Unit 1 Reactor Vessel Material Surveillance Program Withdrawal Schedule DCL-23-034, 2022 Annual Nonradiological Environmental Operating Report2023-05-0101 May 2023 2022 Annual Nonradiological Environmental Operating Report DCL-23-036, 2022 Annual Radiological Environmental Operating Report2023-05-0101 May 2023 2022 Annual Radiological Environmental Operating Report DCL-23-025, 2022 Annual Radioactive Effluent Release Report2023-05-0101 May 2023 2022 Annual Radioactive Effluent Release Report DCL-2023-512, Submittal of Receiving Water Monitoring Program 2022 Annual Report2023-04-27027 April 2023 Submittal of Receiving Water Monitoring Program 2022 Annual Report DCL-23-035, Response to Request for Additional Information on Request Regarding Senior Reactor Operator License Application2023-04-24024 April 2023 Response to Request for Additional Information on Request Regarding Senior Reactor Operator License Application DCL-23-028, Technical Specification Bases, Revision 142023-04-24024 April 2023 Technical Specification Bases, Revision 14 DCL-2023-511, Report on Discharge Monitoring for the First Quarter of 20232023-04-20020 April 2023 Report on Discharge Monitoring for the First Quarter of 2023 DCL-23-031, Submittal of Annual Report of Occupational Radiation Exposure for 20222023-04-19019 April 2023 Submittal of Annual Report of Occupational Radiation Exposure for 2022 DCL-23-024, Independent Spent Fuel Storage Installation, Response to Nrg Request for Additional Information for Revision to License Amendment Request 22-01 Request for Approval of Alternative Security Measures for Early Warning System2023-04-0404 April 2023 Independent Spent Fuel Storage Installation, Response to Nrg Request for Additional Information for Revision to License Amendment Request 22-01 Request for Approval of Alternative Security Measures for Early Warning System DCL-23-022, 2023 Annual Statement of Insurance for Pacific Gas and Electric Companys Diablo Canyon Power Plant2023-03-29029 March 2023 2023 Annual Statement of Insurance for Pacific Gas and Electric Companys Diablo Canyon Power Plant DCL-23-023, Decommissioning Funding Report for Diablo Canyon Power Plant, Units 1 and 22023-03-28028 March 2023 Decommissioning Funding Report for Diablo Canyon Power Plant, Units 1 and 2 DCL-23-021, Independent Spent Fuel Storage Installation, Emergency Plan Update2023-03-23023 March 2023 Independent Spent Fuel Storage Installation, Emergency Plan Update DCL-23-020, Responses to NRC Questions Regarding License Renewal Efforts2023-03-17017 March 2023 Responses to NRC Questions Regarding License Renewal Efforts DCL-23-009, Owner'S Activity Report for Unit 2 Twenty-Third Refueling Outage2023-02-22022 February 2023 Owner'S Activity Report for Unit 2 Twenty-Third Refueling Outage DCL-23-008, Request Regarding Senior Reactor Operator License Application2023-02-22022 February 2023 Request Regarding Senior Reactor Operator License Application DCL-2023-503, Annual Sea Turtle Report2023-01-26026 January 2023 Annual Sea Turtle Report DCL-2023-502, (DCPP) 4th Quarter 2022 Report on Discharge Self-Monitoring2023-01-18018 January 2023 (DCPP) 4th Quarter 2022 Report on Discharge Self-Monitoring DCL-22-091, Revised Steam Generator Tube Inspection Report for Twenty-First Refueling Outage2022-12-20020 December 2022 Revised Steam Generator Tube Inspection Report for Twenty-First Refueling Outage DCL-22-089, Core Operating Limits Report for Unit 2 Cycle 242022-12-20020 December 2022 Core Operating Limits Report for Unit 2 Cycle 24 DCL-22-085, Request to Resume Review of the License Renewal Application or, Alternatively, for an Exemption from 10 CFR 2.109(b), Concerning a Timely Renewal Application2022-10-31031 October 2022 Request to Resume Review of the License Renewal Application or, Alternatively, for an Exemption from 10 CFR 2.109(b), Concerning a Timely Renewal Application DCL-22-041, Site-Specific Decommissioning Cost Estimate, Revision 12022-10-12012 October 2022 Site-Specific Decommissioning Cost Estimate, Revision 1 DCL-22-042, Post-Shutdown Decommissioning Activities Report, Revision 12022-10-12012 October 2022 Post-Shutdown Decommissioning Activities Report, Revision 1 2024-01-29
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Pacific Gas and Electric Company James R. Becker Diablo Canyon Power Plant Site Vice President Mail Code 104/5/601
- p. O. Box 56 Avila Beach, CA 93424 805.545.3462 Internal: 691.3462 November 24, 2010 Fax: 805.545.6445 PG&E Letter DCL-1 0-149 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-323, OL-DPR-82 Diablo Canyon Unit 2 Response to NRC Request for Additional Information Regarding the 180-Day Steam Generator Report for Diablo Canyon Power Plant Unit 2 Fifteenth Refueling Outage
Dear Commissioners and Staff:
Pacific Gas and Electric Company (PG&E) Letter DCL-10-050 dated May 5,2010, submitted the "180-day Steam Generator "Report for Diablo Canyon Power Plant Unit 2 Fifteenth Refueling Outage." The NRC requested additional information regarding the 180-day steam generator report by email dated September 27,2010 (ML102980282).
Enclosed are the NRC questions and PG&E's response to each question.
PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.
This letter includes no revisions to existing regulatory commitments.
If you have any questions or require additional information, please contact Tom Baldwin at (805) 545-4720.
pns3/6984/50343949 Enclosure cc/enc: Elmo E. Collins, NRC Region IV Michael S. Peck, NRC, Senior Resident Inspector Alan B. Wang, Project Manager, Office of Nuclear Reactor Regulation Diablo Distribution
Enclosure PG&E Letter DCL-10-149 PG&E Response to NRC Request for Additional Information Regarding the 180-Day Steam Generator Report for Diablo Canyon Power Plant Unit 2 Fifteenth Refueling Outage NRC Question 1:
- 1. Please provide the following information pertaining to your steam generators (SGs):
Tubesheet map depicting the row and column numbers Sketch of the SG depicting the tube support naming convention The thickness of the tubesheet with and without cladding Tube support plate material and thickness U-bend support material and design Steam generator fabricator Tube manufacturer Tube pitch Method and extent of tube expansion within the tubesheet (e.g., hydraulic)
Tube support plate hole configuration (e.g., quatrefoil shaped openings)
Extent to which any tubes were stress relieved following bending Smallest U-bend radius and associated tube row PG&E Response:
Tubesheet map depicting the row and column numbers.
Figure 1 provides the Westinghouse Delta 54 SG tubesheet map depicting the row and column numbers.
Sketch of the SG depicting the tube support naming convention.
Figure 2 provides the Westinghouse Delta 54 SG sketch depicting the tube support plate naming convention.
The thickness of the tubesheet with and without cladding.
The tubesheet is 23.55 inches thick, including the 0.30-inch cladding. It is 23.25 inches thick without the cladding.
Tube support plate material and thickness.
The eight tube support plates (TSP) are stainless steel (Type 405) and are 1.125 inches thick.
1
Enclosure PG&E Letter DCL-10-149 U-bend support material and design.
In the U-bend, the tubes are supported by three sets of V shaped, rectangular stainless steel (Type 405) anti-vibration bars (AVB). The AVB assemblies stiffen the U-bend region of the tube bundle and facilitate proper tube spacing and tube alignment while mitigating tube vibration. The Diablo Canyon Power Plant replacement steam generator AVB utilize a larger width compared to the original steam generator design to reduce the potential for tube wear at AVB intersections. The lowest set of AVB assemblies supports the tubes in rows 8 through 96. The middle set of AVB assemblies support the tubes in rows 22 through 96. The upper set of AVB assemblies support the tubes in rows 43 through 96.
Steam generator fabricator.
The SG fabricator was Ensa.
Tube manufacturer.
The tube manufacturer was Sandvik.
Tube pitch.
The tubes are arranged in a triangular pattern of 96 rows (parallel to the tube lane) and 119 columns (perpendicular to the tubelane). The triangular pitch is 1.144 inches.
Method and extent of tube expansion within the tubesheet (e.g., hydraulic).
The tubes are full depth hydraulically expanded within the tubesheet. The end of each tube is tack expanded using a urethane plug expansion process.
Tube support plate hole configuration (e.g., quatrefoil shaped openings).
All tube support plates have trefoil-shaped holes, produced by broaching.
Extent to which any tubes were stress relieved following bending.
The tubes in rows 1 through 16 were full-length stress relieved following bending.
Smallest U-bend radius and associated tube row.
Row 1 has the smallest U-bend radius of 3.25 inches.
2
Enclosure PG&E Letter DCL-10-149 NRC Question 2:
On page 4 of your May 5, 2010 letter, it states that 12 tubes were reported with proximity indication signals in the U-bend region. Please identify the tubes and discuss the cause of the indications.
PG&E Response:
As discussed in PG&E's May 5, 2010 letter, 12 tubes were reported with proximity signals (PRO) in the U-bend region during both the preservice inspection (PSI) bobbin coil inspection and the Unit 2 fifteenth refueling outage (2R15) inservice inspection with bobbin and +Point. No tube wear is associated with the signals. These U-bend signals are attributed to the proximity of a given tube to another tube. Signals are reported in pairs of adjacent tubes in the same column at nearly the same axial location along the tube. This confirms that the signal pairs are related to each other in that each tube contributed to the signal in the other.
Table 1 provides a list of the tubes with PRO signals in 2R15, along with the location of the signals in the U-bend and the associated bobbin voltage. The signals occur in high radius U-bends at the flank locations of the bend region.
The logical cause of the proximity indications is a reduced tube-to-tube gap condition. A proximity signal can be generated on the bobbin coil if two tubes experience such a condition. A potential cause of a reduced tube-to-tube gap condition is manufacturing tolerances on a tube-to-tube basis, such as tolerances on U-bend profile and tube overall height. A tolerance stack-up indicates that a reduced gap may occur but tube-to-tube contact is not possible. Manufacturing tolerances on the U-bend profile are slightly larger in higher radius U-bend tubes.
Westinghouse has noted that this condition is not new to the industry. Westinghouse indicates that the tubes are not contacting each other based on the signal amplitude responses observed during 2R15 and on eddy current testing performed in support of another operating unit with the same condition.
NRC Question 3:
Please clarify what the trough region is that is referenced in Section g.3.3 of your May 5, 2010 letter.
PG&E Response:
The trough region is a peripheral secondary side groove with a 2-inch corner radius, thus a 4-inch wide trough. The groove extends to a depth of 3.75 inches below the top of tubesheet and extends around the entire tubesheet. The trough has two drain holes 3
Enclosure PG&E Letter DCL-10-149 that connect to the integrated blowdown line. The purpose of the trough is to allow the top of tubesheet to fully drain.
4
Enclosure PG&E Letter DCL-10-149 Table 1 2R15 Bobbin Proximity Indications (PRO)
Bobbin Bobbin SG Row Col Volts Indication Elevation From - To 21 94 54 0.64 PRO AV1 11.19 TO+37.92 21 96 54 1.48 PRO 8H 19.96 TO+67.59 22 93 47 0.73 PRO AV4 20.5 TO+55.12 22 95 47 0.71 PRO AV4 13.57 TO+58.38 22 93 73 0.67 PRO AV4 2.66 TO+48.21 22 95 73 0.79 PRO AV4 2.78 TO+45.07 23 94 62 1.49 PRO AV1 7.41 TO+32.05 23 96 62 1.02 PRO AV1 11.64 TO+24.74 24 89 69 0.8 PRO AV5 1.2 TO+44.51 24 91 69 0.65 PRO AV5 1.63 TO+49.08 24 93 73 0.87 PRO AV4 8 TO+54.40 24 95 73 0.52 PRO AV4 1.78 TO+51.68 5
Enclosure PG&E Letter DCL-10-149 Figure 1 DCPP Unit 1 and 2 Westinghouse Delta 54 Steam Generator Tubesheet Map Rows Columns 6
Enclosure PG&E Letter DCL-10-149 AV3 AV4 AV2 AV5 AV1 AV6 08H 08C 44.00" 07H 07C 44.00" 06H 06C 44.00" 05C 05H 44.00" 04H 04C 44.00" 03H 03C 44.00" 02H 02C 44.00" 01H 01C 20.55" TSH TSC 23.55" TEH TEC ROW 96 ROW 8 ROW 1 Westinghouse Delta 54 RSG Support thickness is 1.125" TSP Spacing values are center to center Figure 2 Sketch of DCPP Unit 1 and 2 Westinghouse Delta 54 Steam Generator 7
LAR/RAI COMMITMENT TRACKING MEMO (Remove prior to NRC submittal)
Document: PG&E Letter DCL-10-149
Subject:
Response to NRC Request for Additional Information Regarding the 180-Day Steam Generator Report for Diablo Canyon Power Plant Unit 2 Fifteenth Refueling Outage File Location S:\RS\Draft DCLs\RAI Response to 2R15 SG Report.doc FSAR Update Review Utilizing the guidance in XI3.ID2, does the FSAR Update need to be revised?
Yes No If "Yes", submit an FSAR Update Change Request in accordance with XI3.ID2 (or if this is an LAR, process in accordance with WG-9)
Statement of Commitment:
N/A Clarification: None BEFORE OR AFTER LICENSE AMENDMENT RECEIPT When will commitment be implemented?
Notification/Order # Task/Operation #
Tracking Document:
NAME ORGANIZATION CODE Assigned To:
FIRM or TARGET DUE DATE:
Commitment Code:
YES or NO IF YES, WHICH? (E.G., 2R9, 1R10, ETC.)
Outage Commitment?
YES (Specify #) or NO IF YES, LIST THE IMPLEMENTING DOCUMENTS (IF KNOWN)
New PCD Commitment?
YES (Specify #) or NO IF YES, CLARIFY HOW COMMITMENT IS TO BE REVISED Modifies Existing Commitment in PCD?
Ensure that commitment issues are addressed in the submittal cover letter per XI4.ID1.