CNL-25-047, Application for Subsequent Renewed Operating Licenses, Fifth Safety Supplement
| ML25063A184 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/04/2025 |
| From: | Hulvey K Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| CNL-25-047, EPID L-2024-SLE-0000 | |
| Download: ML25063A184 (1) | |
Text
1101 Market Street, Chattanooga, Tennessee 37402 CNL-25-047 March 4, 2025 10 CFR 54 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1, 2, and 3 Renewed Facility Operating License Nos. DPR-33, DPR-52, and DPR-68 NRC Docket Nos. 50-259, 50-260, and 50-296
Subject:
Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, Fifth Safety Supplement (EPID L-2024-SLE-0000)
Reference:
- 1. TVA Letter to NRC, CNL-24-001, Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, dated January 19, 2024 (ML24019A010, ML24019A011)
- 2. TVA Letter to NRC, CNL-24-011, Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, Supplemental Information - Neutron Fluence Analyses Methodology, dated January 22, 2024 (ML24022A292, ML24022A293)
- 3. TVA Letter to NRC, CNL-24-043, Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, Second Safety Supplement (EPID: L-2024-SLE-0000), dated November 1, 2024 (ML24306A203)
- 4. TVA Letter to NRC, CNL-24-081, Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, Third Safety Supplement (EPID L-2024-SLE-0000), dated December 17, 2024 (ML24352A216, ML24352A217)
- 5. TVA Letter to NRC, CNL-25-021, Browns Ferry Nuclear Plant, Units 1, 2, and 3 - Application for Subsequent Renewed Operating Licenses, Fourth Safety Supplement (EPID L-2024-SLE-0000), dated February 12, 2025 (ML25043A035)
By Reference 1, the Tennessee Valley Authority (TVA) submitted a Subsequent License Renewal Application (SLRA) for the Browns Ferry Nuclear Plant, Units 1, 2, and 3, Renewed Facility Operating Licenses in accordance with Title 10 of the Code of Federal Regulations, Part 54, Requirements for Renewal of Operating Licenses for Nuclear Power Plants. By Reference 2, TVA provided the first safety supplement to the SLRA.
U.S. Nuclear Regulatory Commission CNL-25-047 Page 2 March 4, 2025 Since March 2024, TVA has been engaged with the Nuclear Regulatory Commission (NRC) staff in the safety audit of the SLRA. By References 3, 4, and 5, the second, third, and fourth SLRA safety supplements, respectively, were submitted to address additional NRC information needs resulting from the audit as well as miscellaneous errata changes identified by TVA since the submittal of the SLRA. This fifth safety supplement is provided to address additional NRC information needs resulting from this ongoing audit.
The enclosure to this supplement addresses Technical Review Package (TRP)-076 and provides a description of the change, the affected pages in the SLRA, and a markup of the SLRA pages.
There are no new commitments made in this letter. Should you have any questions regarding this submittal, please contact Peter J. Donahue, Director, Subsequent License Renewal at pjdonahue@tva.gov.
I declare under penalty of perjury that the foregoing is true and correct. Executed on this 4th day of MDUFK 2025.
Respectfully, Kimberly D. Hulvey General Manager, Nuclear Regulatory Affairs and Emergency Preparedness
Enclosure:
TRP-076: SLRA Section 3.5.2.2.6: Reduction of Strength and Mechanical Properties of Concrete Due to Irradiation cc: (Enclosure)
NRC Regional Administrator - Region II NRC Branch Chief - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager, License Renewal Projects Branch (Safety)
State Health Officer, Alabama Department of Public Health (w/o Enclosure)
Digitally signed by Edmondson, Carla Date: 2025.03.04 11:02:19 -05'00'
CNL-25-047 ENCLOSURE TRP-076: SLRA Section 3.5.2.2.6:
Reduction of Strength and Mechanical Properties of Concrete Due to Irradiation (6 pages)
Title of Supplement Enclosure Document:
TRP - 076: SLRA Secon 3.5.2.2.2.6: Reducon of Strength and Mechanical Properes of Concrete Due to Irradiaon Descripon of SLRA change(s) aached:
TRP-076 Non-Aributed Question - The List of Figures on page xxi and SLRA Secon 3.5.2.2.2.6 on page 3-695 are being revised to incorporate a simplified diagram of the Reactor Vessel, Pedestal, and Shield Wall Configuration (3.5.2-1).
Page 1 of 1
TRP076 Non-Attributed Question SLRATable of Contents Page xxi
List of Figures Browns Ferry Nuclear Plant Subsequent License Renewal Application (Rev. 0) xxi LIST OF FIGURES Figure 2-1, BFN Unit 1/2 SBO Alternate AC Source and Recovery Path Boundaries............................2-13 Figure 2-2, BFN Unit 1/2 SBO Alternate AC Source and Recovery Path Boundaries (continued).........2-14 Figure 2-3, BFN Unit 3 SBO Alternate AC Source and Recovery Path Boundaries...............................2-15 Figure 4.2.1-1, BFN Unit 1 - Reactor Vessel - Beltline Components......................................................4-15 Figure 4.2.1-2, BFN Unit 2 - Reactor Vessel - Beltline Components...................................................... 4-17 Figure 4.2.1-3, BFN Unit 3 - Reactor Vessel - Beltline Components...................................................... 4-19 Figure 3.5.2-1, Simplified Diagram of the Reactor Vessel, Pedestal, and Shield Wall Configuration.....3-695a
TRP076 Non-Attributed Question SLRASection 3.5.2.2.2.6 Page 3 - 695
Section 3 - Aging Management Review Results Browns Ferry Nuclear Plant Subsequent License Renewal Application (Rev. 0) 3-695 sacrificial shield wall, and the reactor vessel support/pedestal structure. Data related to the effects and significance of neutron and gamma radiation on concrete mechanical and physical properties is limited, especially for conditions (dose, temperature, etc.) representative of light-water reactor (LWR) plants. However, based on literature review of existing research, radiation fluence limits of 1 x 1019 neutrons/cm2 neutron radiation and 1 x 108 Gy (1 x 1010 rad) gamma dose are considered conservative radiation exposure levels beyond which concrete material properties may begin to degrade markedly (Ref. 17, 18, 19).
Further evaluation is recommended to determine the need for a plant-specific AMP or plant-specific enhancements to selected existing AMPs to manage the aging effects of irradiation if the estimated (calculated) fluence levels or irradiation dose received by any portion of the concrete from neutron (fluence cutoff energy E > 0.1 MeV) or gamma radiation exceeds the respective threshold level during the subsequent period of extended operation that could affect intended functions. Higher fluence or dose levels may be allowed in the concrete if tests and/or calculations are provided to evaluate the reduction in strength and/or loss of mechanical properties of concrete from those fluence levels, at or above the operating temperature experienced by the concrete, and the effects are applied to the design calculations. Supporting calculations/analyses, test data, and other technical basis are provided to estimate and evaluate fluence levels and the plant-specific program. The acceptance criteria are described in BTP RLSB-1 (Appendix A.1 of this SRP-SLR).
Table 3.5.1 Item Number 3.5-1, 097: The potential for reduction of strength, loss of mechanical properties, and cracking of reinforced concrete due to irradiation primarily concerns the reactor vessel shield wall, also called the sacrificial shield wall or the containment biological shield (CBS), which is located around the reactor vessel in the drywell. The CBS is described in the BFN FSAR Section 12.2.2.6. Demonstrated with Figure 3.5.2-1, tThe reactor vessel is supported from the bottom on a skirt on the reactor vessel support/pedestal structure, as described in FSAR Section 12.2.2.3.3, where the radiation exposure is much lower than at the CBS along the reactor vessel belt line. The reactor vessel support/pedestal structure is a reinforced concrete hollow cylinder supporting both the reactor vessel and the CBS. The bottom and top portions of the shield wall are comprised of standard density concrete with limestone aggregate. The central portion of the CBS is comprised of high-density concrete with hematite aggregate.
The estimated (calculated) fluence levels or irradiation dose received by any portion of the concrete from neutron (E > 0.1 MeV) or gamma radiation does not exceed the respective threshold level limits of 1E+19 neutrons/cm2 neutron radiation or 1E+10 rad gamma dose during the subsequent period of extended operation; additionally, there was no plant-specific operating experience identified that reflects irradiation damage that could impact the intended function of the CBS. Therefore, a plant-specific program to manage aging effects of irradiation is not required and the Structures Monitoring program (B.2.1.33) will be used to manage the potential for reduction of strength, loss of mechanical properties, and cracking due to irradiation of reinforced concrete near reactor vessel (CBS).
SLRA Table 4.2.1.1-4 shows a maximum fluence level of 1.69E+18 neutrons/cm2 neutron radiation (E > 1 MeV) at the inner diameter of the reactor vessel at the belt line for the 64 Effective Full Power Years (EFPY) projected for the period of subsequent period of extended operation. The maximum estimated fluence levels at the concrete are based on determining the attenuation by the intervening reactor vessel shell and air gap and determining the neutron fluence levels at the energy levels of interest regarding potential concrete damage. The following
S/R$ Figure -1: Simplified Diagram of the Reactor Vessel, Pedestal, and Shield Wall Configuration Section 3 - Aging Management Review Results Browns Ferry Nuclear Plant Subsequent License Renewal Application (Rev. 0) 3-695D