Text

Duke Energy Carolinas, Llc., License Amendment Request Proposing to Revise Technical Specification 3.4.3, RCS Pressure and Temperature (P/T) Limits
	ML25303A005
Person / Time
Site:	Oconee
Issue date:	10/30/2025
From:	Snider S; Duke Energy Carolinas
To:	; Office of Nuclear Reactor Regulation, Document Control Desk
Shared Package
ML25303A004	List: RA-21-0015, Duke Energy Carolinas, Llc., License Amendment Request Proposing to Revise Technical Specification 3.4.3, RCS Pressure and Temperature (P/T) Limits;
References
	TS 3.4.3, RA-21-0015
	Download: ML25303A005 (1)
	v • d • e

Steven M. Snider Vice President Oconee Nuclear Station Duke Energy ON01VP l 7800 Rochester Hwy Seneca, SC 29672 o: 864.873.3478 f: 864.873.5791 Steve.Snider@duke-energy.com PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 TO THE ENCLOSURE THIS LETTER IS UNCONTROLLED 10 CFR 50.90 RA-21-0015 October 30, 2025 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Duke Energy Carolinas, LLC Oconee Nuclear Station (ONS), Units 1, 2, and 3 Docket Numbers 50-269, 50-270, and 50-287 Subsequent Renewed Facility Operating License Nos. DPR-38, DPR-47, and DPR-55

Subject:

License Amendment Request Proposing to Revise Technical Specification 3.4.3, RCS Pressure and Temperature (P/T) Limits Pursuant to 10 CFR 50.90, Duke Energy Carolinas, LLC (Duke Energy) proposes to amend the Technical Specifications (TS) for Oconee Nuclear Station (ONS) Units 1, 2, and 3. The proposed change would revise TS 3.4.3, RCS Pressure and Temperature (P/T) Limits, to reflect an update to the P/T limit curves for all three units in TS Figures 3.4.3-1 through 3.4.3-9.

The proposed change will also reflect that the revised ONS P/T limit curves in TS 3.4.3 are applicable to 72 EFPY (i.e., 80 years of operation).

The proposed change is necessary because the existing ONS P/T limits curves in TS 3.4.3 are only applicable up to 44.6 EFPY (Unit 1), 45.3 EFPY (Unit 2), and 43.8 EFPY (Unit 3). ONS Unit 3 is expected to reach 43.8 EFPY in December 2026.

The Enclosure to this letter provides a description and assessment of the proposed change. to the Enclosure provides the existing TS pages marked to show the proposed change. Attachment 3 provides a proprietary Framatome report ANP-4122P, Revision 0, Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request, in support of the proposed change. In accordance with 10 CFR 2.390, Duke Energy requests that Attachment 3 be withheld from public disclosure. An affidavit is included (Attachment 2) attesting to the proprietary nature of the information. A non-proprietary version of Attachment 3 is provided as Attachment 4.

PROPRIETARY INFORMATION - WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 TO THE ENCLOSURE THIS LETTER IS UNCONTROLLED

PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 TO THE ENCLOSURE THIS LETTER IS UNCONTROLLED U.S. Nuclear Regulatory Commission RA-21-0015 Page 2 The proposed change has been evaluated in accordance with 10 CFR 50.91(a)(1) using criteria in 10 CFR 50.92(c), and it has been determined that the proposed change involves no significant hazards consideration. The basis for this determination is included in the Enclosure.

Duke Energy requests approval of the proposed amendment to the ONS TS by September 30, 2026. As noted above, the Unit 3 PIT limit curves are expected to expire in December 2026.

Once approved, Duke Energy will implement the license amendments within 90 days.

In accordance with 10 CFR 50.91, Duke Energy is notifying the State of South Carolina of this license amendment request by transmitting a copy of this letter and Enclosure to the designated State Official.

This submittal contains no regulatory commitments.

Please refer any questions regarding the submittal to Ryan Treadway, Director - Nuclear Fleet Licensing, at 980-373-5873.

I declare under penalty of perjury that the foregoing is true and correct. Executed on October 30, 2025.

Steven M. Snider Vice President Oconee Nuclear Station

Enclosure:

Description and Assessment of the Proposed Change cc:

USNRC Region II Regional Administrator USN RC Senior Resident Inspector for ONS USN RC NRR Project Manager for ONS R.Mack(mackrs@dhec.sc.gov), SC DHEC, Bureau of Environmental Health Services PROPRIETARY INFORMATION -WITHHOLD UNDER 10 CFR 2.390 UPON REMOVAL OF ATTACHMENT 3 TO THE ENCLOSURE THIS LETTER IS UNCONTROLLED

RA-21-0015 Enclosure Page 1 of 10 ENCLOSURE DESCRIPTION AND ASSESSMENT OF THE PROPOSED CHANGE

Subject:

License Amendment Request Proposing to Revise Technical Specification 3.4.3, RCS Pressure and Temperature (P/T) Limits

1.

SUMMARY

DESCRIPTION

2.

DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Technical Specifications Requirements 2.3 Reason for the Proposed Change 2.4 Description of the Proposed Change

3.

TECHNICAL EVALUATION 3.1 Pressure and Temperature Limits Curves Development 3.2 Regulatory Issue Summary (RIS) 2014-11 Considerations 3.3 Low Temperature Overpressure Protection (LTOP) Setpoint Considerations

4.

REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration Determination Analysis 4.4 Conclusions

5.

ENVIRONMENTAL CONSIDERATION

6.

REFERENCES ATTACHMENTS:

1. Technical Specifications Markup

2. Affidavit of Framatome, Inc.

3. Framatome Licensing Report ANP-4122P, Revision 0, Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request (PROPRIETARY)

4. Framatome Licensing Report ANP-4122NP, Revision 0, Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request (NON-PROPRIETARY)

RA-21-0015 Enclosure Page 2 of 10

1.

SUMMARY

DESCRIPTION Duke Energy Carolinas, LLC (Duke Energy) proposes to amend the Technical Specifications (TS) for Oconee Nuclear Station (ONS) Units 1, 2, and 3. The proposed change would revise TS 3.4.3, RCS Pressure and Temperature (P/T) Limits, to reflect an update to the P/T limit curves for all three units in TS Figures 3.4.3-1 through 3.4.3-9. The proposed change will also reflect that the revised ONS P/T limit curves in TS 3.4.3 are applicable to 72 effective full power years (EFPY) (i.e., 80 years of operation).

2. DETAILED DESCRIPTION 2.1 System Design and Operation All components of the ONS Reactor Coolant System (RCS) are designed to withstand effects of cyclic loads due to system pressure and temperature changes. These loads are introduced by startup (heatup) and shutdown (cooldown) operations, power transients and reactor trips. ONS is required to limit the pressure and temperature changes during RCS heatup and cooldown within the design assumptions and the stress limits for cyclic operation.

The ONS TS contain P/T limit curves for heatup, cooldown, inservice leak and hydrostatic (ISLH) testing and data for the maximum rate of change of reactor coolant temperature. Each P/T limit curve defines an acceptable region for normal operation. The typical use of the curves is operational guidance during heatup or cooldown maneuvering, when pressure and temperature indications are monitored and compared to the applicable curve to determine that operation is within the allowable region.

Operating limits are established that provide a margin to brittle failure of the reactor vessel and piping of the reactor coolant pressure boundary (RCPB).

The P/T limit curves are composite curves established by superimposing limits derived from stress analyses of those portions of the reactor vessel and head that are the most restrictive. At any specific pressure, temperature, and temperature rate of change, one location within the reactor vessel will dictate the most restrictive limit. Across the span of the P/T limit curves, different locations can be more restrictive, and, thus, the curves are composites of the most restrictive regions.

ONS Updated Final Safety Analysis Report (UFSAR) Section 5.3.4 provides additional details regarding the methodology used to develop the P/T limit curves that are contained in the ONS TS.

2.2 Current Technical Specifications Requirements The element of the Limiting Condition for Operation (LCO) for TS 3.4.3 associated with the proposed change is the limit curves for heatup, cooldown, and ISLH testing. The LCO requires that RCS pressure and temperature during normal operational unit heatup and cooldown be maintained within the limits specified in Figures 3.4.3-1 and 3.4.3-2 for Unit 1; Figures 3.4.3-4 and 3.4.3-5 for Unit 2; and Figures 3.4.3-7 and 3.4.3-8 for Unit 3. Note 1 for the LCO states that for leak tests of the RCS, leak tests of connected systems where RCS pressure and temperature are controlling the RCS may be pressurized to within the limits of Figures 3.4.3-3 (Unit 1), 3.4.3-6 (Unit 2), and 3.4.3-9 (Unit 3). Note 2 for the LCO states that for thermal steady

RA-21-0015 Enclosure Page 3 of 10 state hydro tests required by ASME Section XI, the RCS maybe be pressurized to within the limits of Figures 3.4.3-3 (Unit 1), 3.4.3-6 (Unit 2), and 3.4.3-9 (Unit 3).

LCO 3.4.3 limits apply to all components of the RCS, except the pressurizer (see Note 3 of the LCO) and define allowable operating regions and permit many operating cycles while providing a wide margin to non-ductile failure. Violating LCO 3.4.3 limits would result in placing the reactor vessel outside of the bounds of the stress analyses and could increase stresses in other RCPB components.

2.3 Reason for the Proposed Change The existing P/T limit curves represented in Figure 3.4.3-1 through 3.4.3-3 (Unit 1); Figures 3.4.3-4 through 3.4.3-6 (Unit 2); and Figures 3.4.3-7 through 3.4.3-9 (Unit 3) are applicable through 44.6 effective full power years (EFPY), 45.3 EFPY, and 43.8 EFPY, respectively. It is projected that the existing Unit 3 P/T limit curves will first reach its applicability limit (43.8 EFPY) in December 2026. Therefore, the P/T limit curves were updated through 80 years (72 EFPY) of plant operation. The proposed change would replace TS Figures 3.4.3-1 through 3.4.3-9 with these updated P/T limit curves applicable up to 72 EFPY. The proposed change is necessary to ensure the ONS units will continue to have valid P/T limit curves beyond the applicability terms of the existing TS P/T limits.

2.4 Description of the Proposed Change TS 3.4.3, Figure 3.4.3-1, RCS Normal Operational Heatup Limitations Applicable for the First 44.6 EFPY - Oconee Nuclear Station Unit 1, is revised as follows:

The existing RCS heatup limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 44.6 EFPY applicability term in the Figure 3.4.3-1 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-2, RCS Normal Operational Cooldown Limitations Applicable for the First 44.6 EFPY - Oconee Nuclear Station Unit 1, is revised as follows:

The existing RCS cooldown limitations curve is superseded entirely be a new curve applicable up to 72 EFPY.

The 44.6 EFPY applicability term in the Figure 3.4.3-2 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-3, RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First 44.6 EFPY - Oconee Nuclear Station Unit 1, is revised as follows:

The existing ISLH heatup and cooldown limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 44.6 EFPY applicability term in the Figure 3.4.3-3 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-4, RCS Normal Operational Heatup Limitations Applicable for the First 45.3 EFPY - Oconee Nuclear Station Unit 2, is revised as follows:

RA-21-0015 Enclosure Page 4 of 10 The existing RCS heatup limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 45.3 EFPY applicability term in the Figure 3.4.3-4 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-5, RCS Normal Operational Cooldown Limitations Applicable for the First 45.3 EFPY - Oconee Nuclear Station Unit 2, is revised as follows:

The existing RCS cooldown limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 45.3 EFPY applicability term in the Figure 3.4.3-5 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-6, RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First 45.3 EFPY - Oconee Nuclear Station Unit 2, is revised as follows:

The existing ISLH heatup and cooldown limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 45.3 EFPY applicability term in the Figure 3.4.3-6 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-7, RCS Normal Operational Heatup Limitations Applicable for the First 43.8 EFPY - Oconee Nuclear Station Unit 3, is revised as follows:

The existing RCS heatup limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 43.8 EFPY applicability term in the Figure 3.4.3-7 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-8, RCS Normal Operational Cooldown Limitations Applicable for the First 43.8 EFPY - Oconee Nuclear Station Unit 3, is revised as follows:

The existing RCS cooldown limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 43.8 EFPY applicability term in the Figure 3.4.3-8 title is replaced with 72 EFPY.

TS 3.4.3, Figure 3.4.3-9, RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First 43.8 EFPY - Oconee Nuclear Station Unit 3, is revised as follows:

The existing ISLH heatup and cooldown limitations curve is superseded entirely by a new curve applicable up to 72 EFPY.

The 43.8 EFPY applicability term in the Figure 3.4.3-9 title is replaced with 72 EFPY.

The markup of the impacted TS pages provided in Attachment 1 reflects the description of the proposed change above.

RA-21-0015 Enclosure Page 5 of 10

3. TECHNICAL EVALUATION 3.1 Pressure and Temperature Limits Curves Development The technical basis for the proposed change to TS 3.4.3 is provided in Framatome report, ANP-4122P/NP, Revision 0, Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request. The Framatome report is provided as Attachments 3 (Proprietary) and 4 (Non-Proprietary) to this enclosure. As outlined in ANP-4122P/NP, the 72 EFPY P/T limits were developed in compliance with the requirements of 10 CFR 50, Appendix G, utilizing the analytical methods of Babcock and Wilcox (B&W) nuclear steam supply systems, topical report BAW-10046A, Revision 2 (ADAMS Accession No. ML20207G601), and ASME Boiler and Pressure Vessel Code,Section XI, Appendix G (2019 Edition).

Development of the updated P/T limits required an updated neutron fluence assessment for reactor pressure vessel (RPV) materials in ONS Units 1, 2, and 3, as well as projections for future operation through 72 EFPY (representing 80 years of plant operation). The updated fluence calculation method uses the methodology described in topical report ANP-10348P/NP-A, Revision 0 (ADAMS Accession Nos. ML21221A333 and ML21221A334) to predict 72 EFPY fluence. ANP-10348P/NP-A, Revision 0 was approved by the NRC staff and aligns with or exceeds the guidance specified in NRC Regulatory Guide (RG) 1.190, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence. As outlined in Section 2.2.2 of ANP-4122P/NP, the fluence projections incorporate cumulative fluence data from previously analyzed operating cyclescalculated using the NRC-approved methodology from Topical Report BAW-2241-A, Revision 2 (ADAMS Accession No. ML073310655)along with new fluence estimates based on flux calculations performed using the ANP-10348P/NP-A methodology from recent operating cycles. The fluence projections incorporated a correction for Measurement Uncertainty Recapture (MUR) which has been implemented at each ONS unit since the last analyzed operating cycle.

As described in Item IV.A2.R-84 of NUREG-1801, Revision 2 (ADAMS Accession No. ML103490041) and used in the ONS Subsequent License Renewal Application that was approved by the NRC staff (ADAMS Accession No. ML21158A193), all RPV ferritic materials with an end-of-life projected fluence value exceeding 1E+17 n/cm2 (E > 1.0MeV) are considered in the RPV integrity calculations. To support updates to the P/T limits for ONS Units 1, 2, and 3, adjusted reference temperature (ART) values for RPV materials were calculated using the updated 72 EFPY fluence values in accordance with the methodology prescribed in NRC RG 1.99, Revision 2. The ART calculations considered the initial RTNDT (reference nil-ductility transition temperature) values of the unirradiated reactor vessel materials, an estimated irradiation-induced shift (RTNDT), and an added margin term. The ART values were determined through 72 EFPY for each material at the quarter thickness (1/4T) and three-quarter thickness (3/4T) vessel wall locations using the resulting projections from the updated neutron fluence assessment. The limiting projected ART values at 72 EFPY were determined for ONS Units 1, 2, and 3, which were used to develop P/T limit curves for each unit. As discussed in Section 6.0 of ANP-4122P/NP, the updated P/T limit curves were developed in accordance with ASME Boiler and Pressure Vessel Code,Section XI, Appendix G, in which maximum allowable pressures are calculated as a function of the reactor coolant temperature. The resulting ONS P/T limit curves from Figures 6-1 through 6-9 of ANP-4122P/NP are reflected in the mark-ups of

RA-21-0015 Enclosure Page 6 of 10 ONS TS 3.4.3 provided as Attachment 1 to this enclosure. The P/T limit curves have been adjusted for pressure correction based on the difference between the analyzed postulated flaw location and the bounding pressure tap location. The P/T limit curves presented in to this enclosure do not include margins for instrument error.

3.2 Regulatory Issue Summary (RIS) 2014-11 Considerations 10 CFR 50, Appendix G requires that P/T limits be developed to bound all ferritic materials in the RPV. RIS 2014-11 (Reference 1) clarifies that P/T limit calculations for ferritic RPV materials other than those with the highest reference temperature may define P/T limit curves due to the consideration of stress levels from structural discontinuities (such as RPV inlet and outlet nozzles) which may produce a lower allowable pressure. RIS 2014-11 specifically focused on those portions of the vessel known as the extended beltline, which are materials outside of the traditional RPV beltline which are predicted to exceed a fluence level of 1.0 x 1017 n/cm2. The updated fluence analysis and the calculation of new 72 EFPY ART values considered both the traditional beltline and extended beltline materials. The updated fluence analysis determined that the RPV inlet and outlet nozzles will not be limiting with respect to the P/T limit curves based on applicability to topical report PWROG-15109-NP-A (Reference 2).

PWROG-15109-NP-A was developed to generically address RPV nozzle P/T limit curves for the U.S. pressurized water reactor (PWR) fleet. The evaluation within PWROG-15109-NP-A demonstrated that a plants P/T limit curves developed with NRC-approved methods bound the nozzle P/T limit curves as long as the plant-specific fluence of the RPV nozzle corners remain less than the screening criterion of 4.28 x 1017 n/cm2. PWROG-15109-NP-A was approved by the NRC (Reference 3) as an acceptable means to address the concerns of RIS 2014-11 for RPV nozzles. Since Section 4.3 of ANP-4122P/NP determined the RPV nozzle fluence at 72 EFPY remains below the screening criterion of 4.28 x 1017 n/cm2, the results and conclusions of PWROG-15109-NP-A apply to ONS Units 1, 2, and 3, and demonstrate the nozzles are not limiting with respect to the P/T limit curves.

3.3 Low Temperature Overpressure Protection (LTOP) Setpoint Considerations LTOP requirements were evaluated with consideration of 72 EFPY P/T limits in which minimum allowable pressures for each ONS unit were determined. The resulting 72 EFPY LTOP allowable pressure that bounds all three ONS units when adjusted for instrument uncertainty was determined to be 540 psig (Unit 1). This bounding LTOP allowable pressure remains above the ONS TS 3.4.12, Low Temperature Overpressure Protection (LTOP) System pressure limit of 535 psig corresponding to the power operated relief valve (PORV) setpoints.

Therefore, the existing LTOP TS limit for PORV setpoints is acceptable for plant operation up to 72 EFPY and no changes are required. The minimum 72 EFPY LTOP enable temperature that bounds all three ONS units with instrument uncertainty applied was determined to be 297.6°F (Unit 3). This value is lower than the existing LTOP enable temperature of 325°F from ONS TS 3.4.12. Therefore, the existing LTOP enable temperature of 325°F remains acceptable for plant operation up to 72 EFPY and no changes are required.

Further discussion of LTOP is provided in Section 6.6 of Attachments 3 and 4 to this enclosure.

RA-21-0015 Enclosure Page 7 of 10

4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria The following regulatory requirements and guidance documents are applicable to the proposed change.

10 CFR 50.36 Title 10 of the Code of Federal Regulations (10 CFR) Section 50.36, Technical specifications, establishes the requirements related to the content of the TS. Pursuant to 10 CFR 50.36(c), TS will include items in the following categories: (1) safety limits, limiting safety system settings, and limiting control settings, (2) LCOs, (3) Surveillance Requirements (SRs), (4) design features; and (5) administrative controls.

ONS LCO 3.4.3 limits the pressure and temperature changes during RCS heatup and cooldown to prevent non-ductile RPV failure. The proposed change revises the ONS P/T limit curves in TS 3.4.3 and reflects that the curves are applicable until 72 EFPY. Based on the determination that the proposed TS Figures 3.4.3-1 through 3.4.3-9 are acceptable up to 72 EFPY, Duke Energy concludes that ONS LCO 3.4.3 will continue to satisfy the requirements of 10 CFR 50.36(c)(2)(i) with the proposed change.

10 CFR 50.60 Section 50.60 of 10 CFR, Acceptance criteria for fracture prevention measures for lightwater nuclear power reactors for normal operation, imposes fracture toughness and material surveillance program requirements, which are set forth in 10 CFR 50, Appendices G, Fracture Toughness Requirements, and H, Reactor Vessel Material Surveillance Program Requirements. With the proposed change, ONS meets the requirements set forth in 10 CFR 50 appendices G and H. Therefore, ONS also satisfies the requirements of 10 CFR 50.60 for the proposed change.

10 CFR 50, Appendix G Appendix G to 10 CFR 50 requires that the P/T limits for the facilitys RPV be at least as conservative as those obtained by following the linear elastic fracture mechanics methodology of Appendix G to Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code). Using the ART values, P/T limit curves were determined in accordance with the requirements of 10 CFR 50, Appendix G. Therefore, Duke Energy concludes for the proposed change that the ONS RPV will continue to meet RPV integrity regulatory requirements through 72 EFPY.

10 CFR 50, Appendix H Appendix H to 10 CFR 50 establishes requirements for each facility related to its RPV material surveillance. The proposed change does not impact the ONS surveillance capsule removal schedule.

RA-21-0015 Enclosure Page 8 of 10 RIS 2014-11 RIS 2014-11 (Reference 1) clarifies that P/T limit calculations for ferritic RPV materials other than those materials with the highest reference temperature may result in more limiting P/T curves because of higher stresses due to structural discontinuities, such as those in RPV inlet and outlet nozzles. Duke Energy appropriately considered RIS 2014-11 for the proposed change in the Technical Evaluation section of the LAR above.

The proposed change does not affect plant compliance with any of the above regulations or guidance and will ensure that the lowest functional capabilities or performance levels of equipment required for safe operation are met.

4.2 Precedent The NRC has previously approved changes similar to the proposed change in this License Amendment Request for other nuclear power plants including:

Catawba Nuclear Station, Unit No. 2: Application dated June 18, 2024 (ADAMS Accession No. ML24170A696); NRC Safety Evaluation dated June 2, 2025 (ADAMS Accession No. ML25086A296).

Catawba Nuclear Station, Unit No. 1: Application dated July 2, 2019 (ADAMS Accession No. ML19183A038); NRC Safety Evaluation dated August 4, 2020 (ADAMS Accession No. ML20174A045).

Oconee Nuclear Station, Unit Nos. 1, 2, and 3: Application dated February 22, 2013 (ADAMS Accession No. ML13058A059); NRC Safety Evaluation dated February 27, 2014 (ADAMS Accession No. ML14041A093). Note: these license amendments established the existing ONS P/T limit curves. The existing applicability terms for the curves were established by the issuance of the license amendments associated with Measurement Uncertainty Recapture Power Uprate (ADAMS Accession No. ML20335A001).

4.3 No Significant Hazards Consideration Determination Analysis Duke Energy Carolinas, LLC (Duke Energy) proposes to amend the Technical Specifications (TS) for Oconee Nuclear Station (ONS) Units 1, 2, and 3. The proposed change would revise TS 3.4.3, RCS Pressure and Temperature (P/T) Limits, to reflect an update to the P/T limit curves for all three units in TS Figures 3.4.3-1 through 3.4.3-9. The proposed change will also reflect that the revised ONS P/T limit curves in TS 3.4.3 are applicable to 72 effective full power years (EFPY) (i.e., 80 years of operation).

Duke Energy has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, Issuance of Amendment, as discussed below:

RA-21-0015 Enclosure Page 9 of 10

1.

Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change revises TS 3.4.3 to reflect updated P/T limit curves in Figures 3.4.3-1 through 3.4.3-9 that are applicable until 72 EFPY. The proposed change does not involve physical changes to the plant or altering the reactor coolant system (RCS) pressure boundary (i.e., there are no changes in operating pressure, materials or seismic loading). The proposed P/T limit curves and Adjusted Reference Temperature (ART) values for TS 3.4.3 with an applicability term of 72 EFPY provide continued assurance that the fracture toughness of the reactor pressure vessel (RPV) is consistent with analysis assumptions and Nuclear Regulatory Commission (NRC) regulations. The methodology used to develop the proposed P/T limit curves provides assurance that the probability of a rapidly propagating failure will be minimized. The proposed P/T limit curves, with the applicability term of 72 EFPY, will continue to prohibit operation in regions where it is possible for brittle fracture of reactor vessel materials to occur, thereby assuring that the integrity of the RCS pressure boundary is maintained.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2.

Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

Response: No.

The proposed change revises TS 3.4.3 to reflect updated P/T limit curves in Figures 3.4.3-1 through 3.4.3-9 that are applicable until 72 EFPY. The proposed change does not affect the design or assumed accident performance of any structure, system or component or introduce any new modes of system operation or failure modes.

Compliance with the proposed P/T limit curves will provide sufficient protection against brittle fracture of reactor vessel materials to assure that the RCS pressure boundary performs as previously evaluated.

Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.

3.

Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

The proposed change revises TS 3.4.3 to reflect updated P/T limit curves in Figures 3.4.3-1 through 3.4.3-9 that are applicable until 72 EFPY. ONS complies with applicable regulations (i.e., 10 CFR 50, Appendices G and H) and adheres to NRC-approved methodologies (i.e., Regulatory Guides 1.99 and 1.190) with respect to the proposed P/T limit curves in TS 3.4.3 to provide an adequate margin of safety to the conditions at which brittle fracture may occur. The proposed P/T limit curves for ONS Units 1, 2, and 3, with an applicability term of 72 EFPY, will continue to provide assurance that the P/T limits are not exceeded.

RA-21-0015 Enclosure Page 10 of 10 Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above, Duke Energy concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.

4.4 Conclusion In conclusion, based on the considerations discussed above: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner; (2) such activities will be conducted in compliance with the Commissions regulations; and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5. ENVIRONMENTAL CONSIDERATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6. REFERENCES

1. NRC Regulatory Issue Summary 2014-11, Information on Licensing Applications for Fracture Toughness Requirements for Ferritic Reactor Coolant Pressure Boundary Components, U.S. Nuclear Regulatory Commission, October 2014 (ADAMS Accession No. ML14149A165).

2. Pressurized Water Reactor Owners Group (PWROG) PWROG-15109-NP-A, Revision 0, PWR Pressure Vessel Nozzle Appendix G Evaluation, January 2020 (ADAMS Accession No. ML20024E573).

3. NRC Safety Evaluation, Final Safety Evaluation by the Office of Nuclear Reactor Regulation for Pressurized Water Reactor Owners Group Topical Report PWROG-15109-NP, Revision 0, PWR Pressure Vessel Nozzle Appendix G Evaluation EPID L-2018-TOP-0009, October 31, 2019 (ADAMS Accession Nos. ML19301D063 and ML19301D160).

RA-21-0015 ATTACHMENT 1 TECHNICAL SPECIFICATIONS MARKUP

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"'C Q)....

ca

-~

"'C C:

2400

-Composite HU Curve Criticality Limit P-T Limit Curve 2000 Normal Heatup Criticality Limit Temp. Press.

Temp. Press.

(OF)

(psig)

(°F) (psig) 60 528 253 0

105 528 253 1124 1600 115 545 270 1364 120 553 290 1771 135 557 310 2374 170 557 170 729 1200 175 804 190 903 210 1089 230 1364 800 250 1771 270 2374 400 Indicated RCS Inlet Temperature, °F REPLACE WITH INSERT A RCS PIT Limits 3.4.3 The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-1 (page 1 of 1)

RCS Normal Operational Heatup Limitations Applicable for the First~

- Oconee Nuclear Station Unit 1 OCONEE UNITS 1, 2, & 3 3.4.3-5 Amendment Nos. 420, 422, & 421

INSERT A

.2>

1/)

C.

2000 Normal Cooldown Temp.

Press.

(°F)

(psig)

-composite CD Curve RCS PIT Limits 3.4.3 251 2231 1-----+-------t------+-----1--::a~ ------t 246 2221 231 1779 e 1600 211 1363 191 1083 l-----+-------t---------.~

--1---+-------t 1/)

1/)

Q)...

a.

Cl) 0 0:::

"'C cu

(.)

"'C C:

190 1053 186 1029 181 981 1200 171 837 l-----+---~,l!,"----------r------+---------1 166 824 161 765 710 636 800 155 146 135 110 105 100 611 l-----------c~ 't--------t-------.,_.,c,_,__--+-----+-------t 400 506 50 REPLACE WITH INSERT 8 100 150 200 250 300 Indicated RCS Inlet Temperature, °F The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-2 (page 1 of 1)

RCS Normal Operational Cooldown Limitations Applicable for the First-+t-:6 EFPY - Oconee Nuclear Station Unit 1 OCONEE UNITS 1, 2, & 3

~

-6 Amendment Nos. 420, 422, & 421

INSERT B

.52>

1/)

C.

Cl)

l 1/)

1/)

Cl)...

a.

Cl) 0 a:

"t, Cl) -

RS

-~

"t, C:

2000 -

1600 1200 800 400 -

ISLH Composite ISLH Composite (HU/CD) Curve Temp.

Press.

(OF)

(psig) 60 553 105 553 110 610 115 752 120 774 170 774 170 1002 175 1103 190 1235 210 1483 230 1852 Indicated RCS Inlet Temperature, °F REPLACE WITH INSERT C RCS PIT Limits 3.4.3 The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-3 (page 1 of 1)

RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First +1-:6-EFPY - Oconee Nuclear Station Unit 1 OCONEE UNITS 1, 2, & 3

~

-7 Amendment Nos. 420, 422, & 421

INSERT C

.!2>

ti) c..

PI ti) ti)

Q)...

a.

en 0

0:::

"O Q) -

RS

-~

"O C:

2400 2000 -

Normal Heatup Temp. Press.

(OF)

(psig) 60 527 1600 105 527 115 543 120 550 170 550 1200 170 776 185 914 205 1145 225 1446 800 240 1764 260 2365 400 REPLACE WITH INSERT D

-Composite HU Curve Criticality Limit P-T Limit Curve Criticality Limit Temp. Press.

(OF)

(psig) 243 0

243 1126 265 1446 280 1764 300 2365 Indicated RCS Inlet Temperature, °F I

I RCS PIT Limits 3.4.3 The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-4 (page 1 of 1)

RCS Normal Operational Heatup Limitations Applicable for the First~

- Oconee Nuclear Station Unit 2 OCONEE UNITS 1, 2, & 3 3.4.3-8 Amendment Nos. 420, 422, & 421

INSERT D

C)

II)

0.

Cl)~...

I II)

II)

Cl)...

a.

en

(.)

0:::

"C.s n:s

(.)

"C C:

RCS PIT Limits 3.4.3 2400 Normal Cooldown Temp.

Press.

(OF)

(psig) 2000 251 2365 241 2365 231 2039 211 1539 1600 191 1203 190 1166 186 1138 176 1021 1200 171 907 166 907 161 871 155 802 800 146 708 135 670 110 105 100 400 518 50 REPLACE WITH INSERT E I

-Composite CD Curve 100 150 200 250 300 Indicated RCS Inlet Temperature, °F The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-5 (page 1 of 1) 72 RCS Normal Operational Cooldown Limitations Applicable for the Firstt; EFPY - Oconee Nuclear Station Unit 2 OCONEE UNITS 1, 2, & 3

.. -9 Amendment Nos. 420, 422, & 421

INSERT E

.!:2>

u, C.

Q)...

I u,

u,

~

a..

Cl) u et:

"t, Q) -

ns

(,)

"t, C:

2400 2000 ISLH Composite Temp.

Press.

(OF)

(psig) 60 557 1600 105 557 110 614 115 753 120 763 1200 170 763 170 1065 190 1316 210 1643 800 ---

225 1958 400 240 REPLACE WITH INSERT F ISLH Composite (HU/CD) Curve Indicated RCS Inlet Temperature, °F RCS PIT Limits 3.4.3 The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-6 (page 1 of 1) 72 RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First~

EFPY - Oconee Nuclear Station Unit 2 OCONEE UNITS 1, 2, & 3

.. -10 Amendment Nos. 420, 422, & 421

INSERT F

.2>

II)

C.

Cl)

I,,.

II)

Q)

I,,.

a.

en u 0::

"'C Q) -

ca CJ

"'C C

2400

--Composite HU Curve

-Criticality Limit P-T Limit Curve 2000 I

Normal Heatup Criticality Limit Temp. Press.

Temp. Press.

(OF)

(psig)

(OF)

(psig) 60 470 275 0

1600 170 470 275 1148 170 638 295 1453 190 746 310 1772 210 907 325 2081 1200 220 990 335 2364 235 1150 255 1453 270 1772 800 275 1856 285 295 400 Indicated RCS Inlet Temperature, °F REPLACE WITH INSERT G I

RCS PIT Limits 3.4.3 I

I

I I

The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-7 (page 1 of 1)

RCS Normal Operational Heatup Limitations Applicable for the First.+e:,e, EFPY - Oconee Nuclear Station Unit 3 OCONEE UNITS 1, 2, & 3

~

11 Amendment Nos. 420, 422, & 421

INSERT G

2400 2000 C)

(/)

Q.

Q)

I,.

1600

(/)

Q)

I,.

ll.

en 1200 u

et::

"O Q) 800 n,

(J "O

C 400 Normal Cooldown Temp.

Press.

(Of)

(psig) 270 2359 255 1895 251 1675 246 1668 241 1559 231 1371 211 1091 206 1037 201 971 195 928 190 860 171 701 166 642 156 582 146 533 135 110 REPLACE WITH Composite CD Curve Indicated RCS Inlet Temperature, °F RCS PIT Limits 3.4.3

-' N_S_E_R_T_H ___ ~ptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-8 (page 1 of 1)

RCS Normal Operational Cooldown Limitations OCONEE UNl:::l::~b~e 3

ror the First 4~-

1

conee ::::~::::0~0

n:

2 3

0 422 421

INSERT H

C)

Ill

a.

of a..

Ill Ill Q) a..

a.

en

(.)

0:::

Q) -

ctl -~

C 2400 2000 1600 1200 800 400 ISLH Composite Temp.

Press.

(OF)

(psig) 60 557 105 557 110 614 115 655 170 655 170 880 190 1024 210 1238 225 1414 240 1649 255 1966 270 REPLACE WITH INSERT I ISLH Composite (HU/CD) Curve Indicated RCS Inlet Temperature, °F RCS PIT Limits 3.4.3 The regions of acceptable operation are below and to the right of the limit curves.

Margins are included for the pressure differential between point of system pressure measurement and the pressure on the reactor vessel region controlling the limit curve. Margins for instrument error are not included.

Note: Heatup and Cooldown rate restrictions and Reactor Coolant Pump combination restrictions during Heatup and Cooldown are required, as identified in text.

Figure 3.4.3-9 (page 1 of 1) 72 RCS Leak and Hydrostatic Test Heatup and Cooldown Limitations Applicable for the First~

EFPY - Oconee Nuclear Station Unit 3 OCONEE UNITS 1, 2, & 3

.. -13 Amendment Nos. 420, 422, & 421

INSERT I

RA-21-0015 ATTACHMENT 2 AFFIDAVIT OF FRAMATOME, INC.

[2 pages follow this cover page]

A F F I D A V I T

1.

My name is Philip A. Opsal. I am Manager, Product Licensing for Framatome Inc. (formally known as AREVA Inc.), and as such I am authorized to execute this Affidavit.

2.

I am familiar with the criteria applied by Framatome to determine whether certain Framatome information is proprietary. I am familiar with the policies established by Framatome to ensure the proper application of these criteria.

3.

I am familiar with the Framatome information contained in Framatome Licensing Report, Document ANP-4122P Revision 0 entitled, Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request referred to herein as this Document. Information contained in this Document has been classified by Framatome as proprietary in accordance with the policies established by Framatome for the control and protection of proprietary and confidential information.

4.

This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by Framatome and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.

5.

This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is requested qualifies under 10 CFR 2.390(a)(4) Trade secrets and commercial or financial information.

6.

The following criteria are customarily applied by Framatome to determine whether information should be classified as proprietary:

(a)

The information reveals details of Framatomes research and development plans and programs or their results.

(b)

Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.

(c)

The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for Framatome.

(d)

The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for Framatome in product optimization or marketability.

(e)

The information is vital to a competitive advantage held by Framatome, would be helpful to competitors to Framatome, and would likely cause substantial harm to the competitive position of Framatome.

The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(c), 6(b) and 6(e) above.

7. In accordance with Framatomes policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside Framatome only as required and under suitable agreement providing for nondisclosure and limited use of the information.

8.

Framatome policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.

9.

The foregoing statements are true and correct to the best of my knowledge, information, and belief.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on July 18, 2025.

Philip A. Opsal Manager, Product Licensing, Framatome Inc.

Philip A. Opsal

RA-21-0015 ATTACHMENT 3 FRAMATOME LICENSING REPORT ANP-4122P, REVISION 0, OCONEE NUCLEAR STATION UNITS 1, 2, AND 3 PRESSURE-TEMPERATURE LIMITS AT 72 EFPY AND TECHNICAL INPUTS TO LICENSE AMENDMENT REQUEST (PROPRIETARY)

[97 pages follow this cover page]

RA-21-0015 ATTACHMENT 4 FRAMATOME LICENSING REPORT ANP-4122NP, REVISION 0, OCONEE NUCLEAR STATION UNITS 1, 2, and 3 PRESSURE-TEMPERATURE LIMITS AT 72 EFPY AND TECHNICAL INPUTS TO LICENSE AMENDMENT REQUEST (NON-PROPRIETARY)

[97 pages follow this cover page]

0414-12-F04 (Rev. 005, 04/10/2024)

Oconee Nuclear Station Units 1, 2, and 3 Pressure-Temperature Limits at 72 EFPY and Technical Inputs to License Amendment Request Licensing Report ANP-4122NP Revision 0 July 2025 (c) 2025 Framatome Inc.

ANP-4122NP Revision 0 0414-12-F04 (Rev. 005, 04/10/2024)

RA-21-0015, Duke Energy Carolinas, Llc., License Amendment Request Proposing to Revise Technical Specification 3.4.3, RCS Pressure and Temperature (P/T) Limits

Text

Subject:

Enclosure:

Subject:

SUMMARY

SUMMARY

SUMMARY

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