NMP2L2948, Emergency License Amendment Request - Changes to Surveillance Requirement 3.6.1.3.12
| ML26075A037 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  (NPF-069) |
| Issue date: | 03/16/2026 |
| From: | Knowles J Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NMP2L2948 | |
| Download: ML26075A037 (0) | |
Text
200 Energy Way Kennett Square, PA 19348 www.constellation.com 10 CFR 50.90 10 CFR 50.91(a)(5)
NMP2L2948 March 16, 2026 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410
SUBJECT:
Emergency License Amendment Request - Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Pursuant to 10 CFR 50.90, ³Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), requests Nuclear Regulatory Commission (NRC) approval of proposed changes to the Technical Specifications (TS),
Appendix A of Renewed Facility Operating License (RFOL) No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2 (NMP2). This approval is being requested on an emergency basis pursuant to 10 CFR 50.91(a)(5).
The proposed changes include a permanent update of the TS Surveillance Requirement (SR) 3.6.1.3.12 for Main Steam Isolation Valve (MSIV) leakage testing to align the allowed maximum Main Steam Line (MSL) leakage to the assumptions in the Analysis of Record (AOR) for evaluation of Loss of Coolant Accident (LOCA) radiological dose using Alternative Source Term (AST) methodology. This will allow NMP2 determination of TS 3.6.1.3, Primary Containment Isolation Valves (PCIVs), operability in accordance with AOR assumptions.
The proposed changes also include a one-time update of TS SR 3.6.1.3.12 to allow operation of NMP2 for a single cycle with the maximum total MSL leakage slightly lower than the assumed AOR value and the maximum single MSL leakage slightly higher than the AOR assumed value.
NMP2 is currently in a refueling outage. During the outage MSIV local leakage rate testing (LLRT) first performed on March 12, 2026, two of the inboard MSIVs each exceeded their as-found TS maximum allowable limit for a single valve. Leakage through one of the two MSIVs was lowered below the current TS maximum allowable limit for a single valve through the performance of extensive maintenance and troubleshooting. The requested TS amendment supports deferral of repairs on the remaining MSIV until the next NMP2 refueling outage in 2028. The proposed changes are being requested on an emergency basis pursuant to 10 CFR 50.91(a)(5).
Constellation
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Docket No. 50-410 March 16, 2026 Page 2 provides an evaluation of the proposed change. Attachments 2 and 3 provide marked-up and clean pages, respectively, of the TS, indicating the proposed change. provides marked-up pages of the TS Bases (TSB) for information only.
CEG requests approval of the proposed change as soon as possible based on emergency circumstances at NMP2 in accordance with the provisions of 10 CFR 50.91(a)(5) but no later than March 22, 2026. This change is necessary to support startup following the current refueling outage. The proposed change, if approved, will be implemented prior to startup from the current NMP2 refueling outage.
The proposed change has been approved by the NMP Plant Operations Review Committee in accordance with the requirements of the CEG Quality Assurance Program.
There are no regulatory commitments contained in this submittal.
In accordance with 10 CFR 50.91, "Notice for public comment; State consultation," paragraph (b), CEG is notifying the State of New York of this application for license amendment by transmitting a copy of this letter and its attachments to the designated State Official.
Should you have any questions concerning this submittal, please contact Adam Donell at (267) 533-5156.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 16th day of March 2026.
Respectfully, Justin W. Knowles Sr. Manager +/- Licensing Constellation Energy Generation, LLC Attachments:
- 1. Evaluation of Proposed Change
- 2. Proposed Technical Specifications Change (Markup)
- 3. Proposed Technical Specifications Change (Clean)
- 4. Proposed Technical Specifications Bases Change (Markup) (For Information Only) cc:
USNRC Region I, Regional Administrator USNRC Senior Resident Inspector +/- NMP USNRC Project Manager, NRR +/- NMP A. L. Peterson, NYSERDA A. Kincaid, NYSPSC
ATTACHMENT 1 Emergency License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410 EVALUATION OF PROPOSED CHANGE
Subject:
Emergency License Amendment Request - Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 1.0
SUMMARY
DESCRIPTION 2.0 DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Facility Operating License and Technical Specification Requirements 2.3 Emergency Condition 2.4 Proposed Change
3.0 TECHNICAL EVALUATION
3.1 Local Leak Rate Testing (LLRT) 3.2 Alternative Source Term (AST) Loss of Coolant Accident (LOCA) Dose 3.3 Environmental Qualification (EQ)
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration 4.4 Conclusions
5.0 ENVIRONMENTAL CONSIDERATION
6.0 REFERENCES
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 1 of 10 1.0
SUMMARY
DESCRIPTION Pursuant to 10 CFR 50.90, ³Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), requests Nuclear Regulatory Commission (NRC) approval of proposed changes to the Technical Specifications (TS),
Appendix A of Renewed Facility Operating License (RFOL) No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2 (NMP2). This approval is being requested on an emergency basis pursuant to 10 CFR 50.91(a)(5).
2.0 DETAILED DESCRIPTION 2.1 System Design and Operation The four main steam lines (MSLs), which penetrate the drywell, are automatically isolated by the Main Steam Isolation Valves (MSIVs). There are two MSIVs on each main steam line, one inside containment (i.e., inboard) and one outside containment (i.e., outboard). The MSIVs are functionally part of the primary containment boundary and leakage through these valves provides a potential leakage path for fission products to bypass secondary containment and enter the environment as a ground level release. Maintaining the combined leakage below the approved Alternative Source Term (AST) Loss of Coolant Accident (LOCA) design basis radiological dose calculation assumptions maintains the dose consequences below the 10 CFR 50.67, Accident source term, limits.
The Primary Containment Leak Rate Test Program (PCLRTP) governs the testing requirements of all MSIVs. Local Leak Rate Tests (LLRT) are performed every refueling outage. MSIV tests are performed by local pressurization. MSIVs are designed to close 3 seconds to prevent pressure transients and 5 seconds to contain fission products and ensure the core is not uncovered following a MSL break.
2.2 Current Facility Operating License and Technical Specification Requirements The NMP2 TS 3.6.1.3, Primary Containment Isolation Valves (PCIVs), Surveillance Requirement (SR) 3.6.1.3.12 currently states:
Verify leakage rate through each MSIV is 39 scfh [standard cubic feet per hour] when tested at 25 psig.
TS specify this SR is to be performed at a frequency in accordance with the 10 CFR 50 Appendix J Testing Program Plan.
2.3 Emergency Condition NMP2 is currently in a refueling outage. During the outage MSIV LLRTs first performed on March 12, 2026, two of the inboard MSIVs each exceeded their as-found current TS maximum allowable limit for a single valve. One MSIV, 2MSS*AOV6A (located inside primary containment) failed the LLRT with a measured leakage rate of approximately 195 scfh. Leakage through the 2MSS*AOV6A MSIV was lowered below the current TS maximum allowable limit for a single valve through the performance of extensive maintenance and troubleshooting. A second MSIV, 2MSS*AOV6D (located inside primary containment) failed the LLRT with a
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 2 of 10 measured leakage of approximately 81 scfh. Additionally, recirculation loop discharge valve 2RCS*MOV18B failed to close on March 9, 2026. The requested TS amendment supports deferral of repairs on 2MSS*AOV6D until the next NMP2 refueling outage in 2028. The proposed changes are being requested on an emergency basis pursuant to 10 CFR 50.91(a)(5).
Based on the current refueling outage plan, this license amendment request would need to be implemented on or before March 23, 2026, in order to prevent affecting outage critical path and causing the delay of NMP2 startup. Failure of multiple MSIVs and an additional large valve (2RCS*MOV18B) was not foreseen based on historical LLRT results for MSIVs performed in previous refueling outages. In-body MSIV maintenance, which would be the next required maintenance technique required to lower 2MSS*AOV6D leakage, also requires specialized vendor support. Lowering 2MSS*AOV6D leakage through in-body valve maintenance would delay startup by approximately 29 hours3.356481e-4 days <br />0.00806 hours <br />4.794974e-5 weeks <br />1.10345e-5 months <br /> and incur an additional approximately 2.15 person-rem of radiological dose. Postponing repair of 2MSS*AOV6D until the next refueling outage would reduce plant staff radiological dose accumulation and prevent a significant delay to startup following the current refueling outage.
Further, NRC approval is needed sooner than can be provided under exigent circumstances, and this license amendment request is timely considering the unplanned nature of the issues and time required to develop the technical justification supporting the proposed change.
Therefore, CEG has determined that emergency circumstances exist and that NMP2 did not knowingly cause the emergent situation. Further, CEG affirms a best effort has been made for a timely license amendment application. Accordingly, CEG requests an expedited review of the proposed emergency license amendment in accordance with the provisions of 10 CFR 50.91(a)(5) to avoid the unnecessary delay of NMP2 startup following the current refueling outage.
2.4 Proposed Change The proposed changes include a permanent update of TS SR 3.6.1.3.12 for MSIV leakage testing to align the allowed maximum MSL leakage to the assumptions in the Analysis of Record (AOR) for evaluation of LOCA radiological dose using AST methodology. This will allow NMP2 determination of TS 3.6.1.3, Primary Containment Isolation Valves (PCIVs), operability in accordance with AOR assumptions.
Because the AOR performs computations based on MSL leakage, not individual MSIV leakage, the proposed SR changes the requirement for maximum leakage to be based on MSL leakage.
Because the AOR assumes both a maximum single MSL and maximum total MSL leakage, SR limits are placed on each of those values. The limits specified in the updated proposed SR 3.6.1.3.12 limits, 79 standard cubic feet per hour (scfh) for a single MSL and 158 scfh for the combined MSIV leakage rate for all four MSLs, are equivalent to the assumed MSL leakage in the AOR, adjusted for the lower test pressure described in References 6.1 and 6.2 and approved in Reference 6.3. When a single MSIV in a line exceeds the 79 scfh requirement, a condition report is generated, and remediation is controlled by the corrective action program to restore compliance.
The proposed changes also include a note providing a one-time update of TS SR 3.6.1.3.12 to allow operation of NMP2 for a single cycle (21) with the maximum MSL leakage for one of the
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 3 of 10 four MSLs slightly higher than the AOR assumed value as evaluated in Section 3. This one-time change would be applicable only for the next NMP2 operating cycle (21).
The proposed change is shown in the TS markup and clean pages in Attachments 2 and 3, respectively. The TSB markup is provided for information only in Attachment 4.
3.0 TECHNICAL EVALUATION
The proposed changes in MSIV/MSL leak rate limits were evaluated for impacts associated with 10 CFR 50.67 and 10 CFR 50.49, Environmental qualification of electric equipment important to safety for nuclear power plants, compliance. The conclusion of the evaluation is that the current design bases remain bounding for the proposed change. The following discussion provides a summary of the evaluation.
3.1 Local Leak Rate Testing (LLRT)
MSIV LLRT currently uses a single acceptance criterion for operability of each single MSIV that ensures the individual and total leakage for all MSLs remains below the values assumed in the current AST LOCA radiological dose AOR. The guidance in NEI 94-01, Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J (Reference 6.7),
calculates the minimum pathway at all times when containment operability is required. This request is to align with the requirements of 10 CFR Part 50, Appendix J to record the leakage through the pathway and not each specific valve in the pathway. To assess the leak rate of the containment the actual leakage is through both the inboard and outboard MSIV. Therefore, the leakage requirement through the MSIVs should follow the same rationale.
NEI 94-01 also requires the maximum pathway leakage to be less than the limit prior to entering a mode where containment integrity is required following a refueling outage or a shutdown that included leak rate testing of the MSIVs. This will ensure margin is maintained to the total allowable leak rate for the MSIVs in the AOR.
The current licensing basis for MSIV LLRT is documented in NMP2 Updated Safety Analysis Report (USAR) Section 6.2, ³CONTAINMENT SYSTEMS.' This section states that the MSIVs shall be Type C tested in accordance with 10 CFR Appendix J. If this proposed amendment is approved, the USAR will be updated to reflect changes to the TS limits for MSIV/MSL leakage.
The maximum path leakage is utilized and verified to be acceptable prior to entering a Reactor Mode where containment is required to be operable. The use of maximum path ensures that a single failure of any MSIV in the MSL will not result in exceeding the TS requirement, supporting analyzed limits.
Minimum path acceptance criterion is only used for As-Found testing and is performed in a Reactor Mode where Containment is not required for the MSIVs. For example, when testing the containment penetrations two values are used when assessing the leak rate of the penetration.
The As-Found leak rate is based on the minimum pathway and the As-Left leak rate is based on the maximum pathway.
When the unit is shut down and the leak rate is measured, both the inboard and outboard MSIVs are closed. This verifies the valves were operable during the cycle so single failure is not
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 4 of 10 required to be assessed during the As-Found leak rate measurement. Prior to startup, to address the potential for a single failure, the maximum pathway leakage is used to verify leakage is below the TS allowable leakage.
3.2 Alternative Source Term (AST) Loss of Coolant Accident (LOCA) Dose The current AST LOCA AOR is consistent with the previous analysis submitted for the most recent NMP2 AST amendment (References 6.4 and 6.8). The analysis models leakage through two of the four main steam lines, with one MSIV open in each. Of the two MSLs, one is considered to be faulted. With one MSIV closed and one open as assumed in the AOR, MSL leakage and MSIV leakage as equivalent. The leakage rate modeled in the current AOR is 100 scfh in each of the two modeled lines (200 scfh total), measured at 40 psig. Using the adjustments described in References 6.1 and 6.2 and approved in Reference 6.3, these AOR leakages can be converted to the TS conditions with the following equation:
=
Q1 = Analysis Leakage Rate Q2 = TS Leakage Rate P1 = Analysis Backpressure P2 = TS Backpressure The value of 100 scfh measured at 40 psig is equivalent to 79 scfh at the SR 3.6.1.3.12 test pressure of 25 psig and the value of 200 scfh measured at 40 psig is equivalent to 158 scfh at the SR 3.6.1.3.12 test pressure of 25 psig.
Single MSL Leakage Total MSL Leakage Assumed Backpressure Current TS 39 scfh 25 psig AOR 100 scfh 200 scfh 40 psig Proposed TS 79 scfh 158 scfh 25 psig Based on the equivalence of these MSL leakage values, the proposed permanent TS change to SR 3.6.1.3.12 is consistent with the AST LOCA radiological dose AOR.
The proposed one-time change to TS SR 3.6.1.3.12 would redistribute the leakage to 83 scfh (at 25 psig) in the first (faulted) line and 72 scfh (at 25 psig) in the second line. Given the ruptured line has the least volume modeled due to the assumed fault, the slight increase of 4 scfh would result in a slightly larger dose than the corresponding decrease in dose in the second line afforded by a 4 scfh decrease in leakage. To ensure a conservative evaluation, the second line leakage is brought down by 7 scfh (at 25 psig) to 72 scfh to ensure the AST LOCA radiological dose AOR remains bounding. There is an overall reduction to 155 scfh total combined MSL leakage compared to a baseline of 158 scfh at 25 psig. The aerosol deposition efficiency has been updated, in accordance with the AOR methodology, to reflect the new MSL leakage distribution.
An assessment was performed to evaluate the impact of the proposed one-time TS SR change MSL leakage distributions using RadTrad 3.03, consistent with the AOR and its methods. The Ll Ll
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 5 of 10 only changes to the analysis were the MSL leakage rate and the associated aerosol deposition efficiency. All other inputs and assumptions remain unchanged from the AOR documented in Reference 6.8. The following table outlines the changing inputs in this assessment.
Input AOR MSIV Leakage Redistribution Assessment Total MSIV Leakage 200 scfh @ 40 psig 196 scfh @ 40 psig Faulted MSIV Leakage 100 scfh @ 40 psig 105 scfh @ 40 psig Intact MSIV Leakage 100 scfh @ 40 psig 91 scfh @ 40 psig Faulted RadTrad Pathway flowrate through MSIV 0.676 cfm (0-24 hrs) 0.338 cfm (24-720 hrs) 0.710 cfm (0-24 hrs) 0.355 cfm (24-720 hrs)
Intact RadTrad Pathway flowrate through MSIV 0.676 cfm (0-24 hrs) 0.338 cfm (24-720 hrs) 0.615 cfm (0-24 hrs) 0.308 cfm (24-720 hrs)
Faulted RadTrad Pathway flowrate to Environment 1.667 cfm (0-24 hrs) 0.833 cfm (24-720 hrs) 1.750 cfm (0-24 hrs) 0.875 cfm (24-720 hrs)
Intact RadTrad Pathway flowrate to Environment 1.667 cfm (0-24 hrs) 0.833 cfm (24-720 hrs) 1.517 cfm (0-24 hrs) 0.758 cfm (24-720 hrs)
Overall Aerosol Removal Efficiency Faulted = 99.67%
Intact = 99.60%
Faulted = 99.64%
Intact = 99.66%
The assessment dose results were slightly lower than the AOR based on the modified MSL leakage redistribution. The dose values below in the AOR columns are the Reference 6.8 results for the Control Room (CR), Exclusion Area Boundary (EAB), and Low Population Zone (LPZ).
The dose values below in the MSIV Leakage Distribution Assessment columns are results using the proposed one time change to MSL leakages for the same locations.
AOR MSIV Leakage Distribution Assessment CR (Rem)
EAB (Rem)
CR (Rem)
EAB (Rem)
Containment Leakage 0.468 0.312 0.364 0.468 0.312 0.364 ESF Leakage 0.348 0.185 0.179 0.348 0.185 0.179 MSIV Leakage 0.620 0.135 0.179 0.599 0.129 0.173 Drywell Bypass Leakage 0.690 0.408 0.178 0.690 0.408 0.178 Wetwell Bypass Leakage 0.017 0.025 0.012 0.017 0.025 0.012 Reactor Building Shine 0.059 0
0 0.059 0
0 External Cloud Shine 0.073 0
0 0.073 0
0 CR Filter Shine 0
0 0
0 0
0 Total 2.275 1.065 0.912 2.254 1.059 0.906 Allowable 5
25 25 5
25 25 Additionally, the AST LOCA radiological dose AOR contains several remaining conservatisms.
Primarily, there remains conservatism associated with not crediting the holdup and deposition in the two steam lines not modeled. If all four lines are included in the model, the leak rate associated with the non-faulted lines is reduced to 1/3 of the 72 scfh discussed above. This large reduction in volumetric flow rate will amplify the holdup and deposition, which in turn will
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 6 of 10 substantially lower the dose consequences associated with the non-faulted steam lines. Overall, it is expected that with four lines modeled, the total MSIV dose would be less than both the MSL Leakage Distribution Assessment and AOR results. Other conservatisms within the AOR and the assessment include no credit for aerosol deposition in the condenser tube area and not crediting the more realistic light duty breathing rate of control room operators. Therefore, there is reasonable assurance that the dose limits prescribed by 10 CFR 50.67 will continue to be met with the proposed one time MSL leakage distribution limits.
3.3 Environmental Qualification (EQ)
The EQ program has been evaluated for both chemical-mechanical and radiological impacts from MSL leakage. The total MSL leakage is reduced so the limiting moisture and heat deposition on the equipment of the AOR would remain bounding. The zone radiation calculations models a total of 200 scfh (at 40 psig) evenly across all MSLs, which was determined to be appropriate EQ modeling. The proposed change in MSL leakage distribution does not impact these results and conclusions. Therefore, there is no impact to the EQ program from MSL leakage as long as the total leak rate does not exceed 200 scfh (at 40 psig).
The MSIVs are designed to close and be leak-tight to isolate the primary reactor coolant system and containment during the worst conditions of pressure, temperature, and steam flow following a break in the main steam line outside containment. The equipment and components potentially impacted by the modified MSL leak rate are located in the main steam tunnel and turbine building, downstream of the MSLs. The normal service environmental conditions in the main steam tunnel or turbine building are due to the fluid flowing through the MSLs when the MSIVs are open and thus not impacted by allowing increased leakage past the closed valve. The bounding accident temperature and pressure profiles in the main steam tunnel and turbine building are associated with a high energy line break (HELB) in the steam tunnel. When the modified MSL leakage is considered, the HELB temperature and pressure profile in these zones continues to bound the LOCA profile. Additionally, the accident humidity in these zones is already assumed to be 100%. Therefore, the proposed change in allowable MSL leakage would contribute no additional environmental impact to equipment qualified for use in the main steam tunnel or the turbine building.
Because there is no change to EQ design basis temperatures, pressure, humidity, or radiation values, the proposed change in MSL leakage has no impact on non-safety related equipment whose failure under postulated environmental conditions could prevent satisfactory accomplishment of safety functions by the safety-related equipment.
No components are required to be added to the EQ equipment list due to the proposed change in allowable MSL leakage.
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria The proposed change has been evaluated to determine whether applicable regulations and requirements continue to be met. CEG has determined that the proposed change does not
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 7 of 10 require any exemptions or relief from the following current applicable regulations and regulatory requirements, which were reviewed in making this determination:
10 CFR 50.36, Technical Specifications 10 CFR 50.49, Environmental qualification of electric equipment important to safety for nuclear power plants 10 CFR 50.67, Accident source term 10 CFR 50, Appendix A, General Design Criterion 16 - Containment design 10 CFR 50, Appendix A, General Design Criterion 56 - Primary containment isolation 10 CFR 50, Appendix J, Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors Regulatory Guide 1.183, Revision 0, Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors The proposed change is consistent with the applicable regulations and regulatory guidance.
4.2 Precedent The following precedents are applicable to this submittal:
In Reference 6.4, the U.S. NRC granted NMP2 an amendment that increased the allowed leakage rate through individual MSIVs consistent with an updated NMP2 AST LOCA analysis. The proposed changes in this request are consistent with the updated NMP2 AST LOCA analysis.
In Reference 6.5, the U.S. NRC granted Limerick Generating Station, Units 1 and 2, an amendment that allowed LLRT to verify leak rates through each main steam line instead of through each MSIV. The proposed changes in this request make an equivalent change to NMP2 TS.
In Reference 6.6, the U.S. NRC granted Limerick Generating Station, Unit 1, an amendment that allowed leakage for a single MSIV to be slightly higher than the TS limit for a single cycle. The proposed changes in this request make an equivalent change to NMP2 TS for a single cycle.
4.3 No Significant Hazards Consideration Pursuant to 10 CFR 50.90, ³Application for amendment of license, construction permit, or early site permit," Constellation Energy Generation, LLC (CEG), requests Nuclear Regulatory Commission (NRC) approval of proposed changes to the Technical Specifications (TS),
Appendix A of Renewed Facility Operating License (RFOL) No. NPF-69 for Nine Mile Point Nuclear Station, Unit 2 (NMP2). This approval is being requested on an emergency basis pursuant to 10 CFR 50.91(a)(5).
Constellation Energy Generation, LLC (CEG) has evaluated whether or not a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 8 of 10 forth in 10 CFR 50.92, ³Issuance of amendment,' as discussed below:
- 1.
Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The increase in the leakage rate limits and change to use Main Steam Line (MSL) leakage instead of individual Main Steam Isolation Valve (MSIV) leakage has been assessed against the radiological consequence analysis of the Loss of Coolant Accident (LOCA). Based on the results of the assessment, it has been demonstrated that, with the requested changes, the dose consequences of the currently approved LOCA analysis remain bounding and are within the acceptance criteria provided by the NRC for use with the Alternative Source Term (AST) methodology in 10 CFR 50.67.
The proposed changes to use MSL leakage and changes to MSL leakage limits do not involve a physical change to any plant structure, system, or component. As a result, no new failure modes of the MSIVs have been introduced.
The changes affect leakage limit assumptions that constitute inputs to the evaluation of the consequences. The radiological consequences of the analyzed LOCA have been evaluated using the plant licensing basis for this accident. The evaluation concludes that the currently approved LOCA analysis bounds the proposed Technical Specification change. Adequate margin to the regulatory limits specified in 10 CFR 50.67 for control room and offsite doses is still available.
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.
These changes do not affect the design or operation of any component in the facility such that new or different equipment failure modes are created. When a single MSIV in a line exceeds the NMP2 criteria for Local Leak Rate Test (LLRT) leakage results, a condition report is generated, and remediation is controlled by the corrective action program to restore compliance. As such, the proposed changes will not create the possibility of a new or different kind of accident from any accident previously evaluated.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 9 of 10
- 3.
Does the proposed change involve a significant reduction in a margin of safety?
Response: No.
The proposed changes will not cause a significant reduction in the margin of safety considering operability will be determined by the single main steam line in which there are two independent and redundant MSIVs, because only one is needed to maintain the safety function associated with main steam isolation. Therefore, the proposed updated TS SR 3.6.1.3.12 requirement to verify individual and total MSL leakage rates ensures the MSIVs remain within their design to limit the effect of radioisotopes exiting the primary containment.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, CEG concludes that the proposed amendment 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 Conclusions 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 Commission¶s 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.
5.0 ENVIRONMENTAL CONSIDERATION
CEG 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, "Standards for Protection Against Radiation." However, the proposed amendment does not involve: (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluent 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, "Criterion for categorical exclusion; identification of licensing and regulatory actions eligible for categorical exclusion or otherwise not requiring environmental review," paragraph (c)(9). Therefore, pursuant to 10 CFR 51.22, paragraph (b), no environmental impact statement or environmental assessment needs to be prepared in connection with the proposed amendment.
6.0 REFERENCES
6.1 Letter from Justin W. Knowles (Constellation Energy Generation, LLC) to U.S. NRC,
³Exemption Request from Certain Requirements of 10 CFR 50, Appendix J, for Nine Mile Point Nuclear Station, Unit 2, License Amendment Request to Revise Surveillance Requirement (SR) 3.6.1.3.12 to a Reduced Test Pressure and Corresponding Leakage
Emergency License Amendment Request Changes to Nine Mile Point Unit 2 Surveillance Requirement 3.6.1.3.12 Page 10 of 10 Rate for Main Steam Isolation Valves,' dated January 29, 2025 (ADAMS Accession No. ML25029A181) 6.2 Letter from Justin W. Knowles (Constellation Energy Generation, LLC) to U.S. NRC,
³Response to Request for Additional Information for License Amendment Request to Revise Surveillance Requirement (SR) 3.6.1.3.12 to a Reduced Test Pressure and Corresponding Leakage Rate for Main Steam Isolation Valves,' dated June 9, 2025 (ADAMS Accession No. ML25155B825) 6.3 Letter from Richard V. Guzman (U.S. NRC) to Mr. Christopher H. Mudrick, Sr.
(Constellation Energy Generation, LLC), ³NINE MILE POINT NUCLEAR STATION, UNIT 2 - ISSUANCE OF AMENDMENT NO. 201, REVISION OF SURVEILLANCE REQUIREMENT TO A REDUCED TEST PRESSURE AND CORRESPONDING LEAKAGE RATE FOR MAIN STEAM ISOLATION VALVES (EPID L-2025-LLA-0019),'
dated February 4, 2026 (ADAMS Accession No. ML26008A004) 6.4 Letter from Michael L. Marshall, Jr. (U.S. NRC) to Mr. Bryan C. Hanson (Exelon Generation Company, LLC), ³NINE MILE POINT NUCLEAR STATION, UNIT 2 -
ISSUANCE OF AMENDMENT NO. 182 TO CHANGE ALLOWABLE MAIN STEAM ISOLATION VALVE LEAK RATES (EPID L-2019-LLA-0115),' dated October 20, 2020 (ADAMS Accession No. ML20241A190) 6.5 Letter from Rachael Davis (U.S. NRC) to David P. Rhoades (Constellation Energy Generation, LLC), ³LIMERICK GENERATING STATION, UNITS 1 AND 2 +/- ISSUANCE OF AMENDMENT NOS. 266 AND 228 RE: MODIFICATION TO TECHNICAL SPECIFICATION 3.6.1.2 AND MAIN STEAM ISOLATION VALVE LEAKAGE REQUIREMENTS (EPID L-2024-LLA-0115),' dated March 31, 2025 (ADAMS Accession No. ML25070A201) 6.6 Letter from V. Sreenivas (U.S. NRC) to Mr. Bryan C. Hanson (Exelon Generation Company, LLC), ³LIMERICK GENERATING STATION, UNIT 1 +/- ISSUANCE OF AMENDMENT NO. 245 REGARDING TECHNICAL SPECIFICATIONS CHANGE TO ALLOW A ONE-TIME INCREASE IN MAIN STEAM ISOLATION VALVE ALLOWABLE LEAKAGE RATE (EPID L-2020-LLA-0064) (EMERGENCY CIRCUMSTANCES),' dated April 9, 2020 (ADAMS Accession No. ML20098C922) 6.7 NEI 94-01 Revision 2-A, ³Industry Guideline for Implementing Performance-Based Option of 10 CFR Part 50, Appendix J,' dated October 2008 (ADAMS Accession No. ML100620847) 6.8 Letter from David T. Gudger (Exelon Generation Company, LLC) to U.S. NRC,
³Response to Request for Additional Information by the Office of Nuclear Reactor Regulation to Support Review of Nine Mile Point Nuclear Station, Unit 2, License Amendment Request to Increase Allowable MSIV Leakage Rates,' dated May 14, 2020 (ADAMS Accession No. ML20135G951)
ATTACHMENT 2 Emergency License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410 Proposed Technical Specifications Change (Markup) 3.6.1.3-13
PCIVs 3.6.1.3 NMP2 3.6.1.3-13 Amendment 91, 182, 201 SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.6.1.3.12 Verify leakage rate through each MSIV is 39 scfh when tested at 25 psig.
In accordance with 10 CFR 50 Appendix J Testing Program Plan SR 3.6.1.3.13 Verify combined leakage rate through hydrostatically tested lines that penetrate the primary containment is within limits.
In accordance with 10 CFR 50 Appendix J Testing Program Plan main steam line J
I?
~-
~
~
\_ and thr~ugh all four main steam lines is< 158 scfh
- During Cycle 21, leakage rate through one main steam line may exceed 79 scfh provided the leakage rate is< 83 scfh and the leakage rate through all four main steam lines is~ 155 scfh.
ATTACHMENT 3 Emergency License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410 Proposed Technical Specifications Change (Clean) 3.6.1.3-13
PCIVs 3.6.1.3 NMP2 3.6.1.3-13 Amendment 91, 182, 201, SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY SR 3.6.1.3.12 Verify leakage rate through each main steam line is 79 scfh and through all four main steam lines is 158 scfh when tested at 25 psig.*
In accordance with 10 CFR 50 Appendix J Testing Program Plan SR 3.6.1.3.13 Verify combined leakage rate through hydrostatically tested lines that penetrate the primary containment is within limits.
In accordance with 10 CFR 50 Appendix J Testing Program Plan
- During Cycle 21, leakage rate through one main steam line may exceed 79 scfh provided the leakage rate is 83 scfh and the leakage rate through all four main steam lines is 155 scfh.
ATTACHMENT 4 Emergency License Amendment Request Nine Mile Point Nuclear Station, Unit 2 Renewed Facility Operating License No. NPF-69 NRC Docket No. 50-410 Proposed Technical Specifications Bases Change (Markup) (For Information Only)
B 3.6.1.3-19
BASES SURVEILLANCE REQUIREMENTS (continued)
SR 3.6.1.3.12 PCIVs B 3.6.1.3 The analyses in Re~ rence 2 are based on leakage that is less than the speojtied leakage rate. Leakage through each Ima in steam line~
MSW must be~ ~ scfh hen tested at 25 psig. The Frequency is required by the 10 CF O Appendix J Testing Program REFERENCES NMP2 Plan.
SR 3.6.1.3.13 and leakage through all four main steam lines must be~ 158 scfh Surveillance of hydrostatically tested lines provides assurance that the calculation assumptions of Reference 1 are met. The acceptance criteria for the combined leakage of all hydrostatically tested lines is 1 gpm times the total number of hydrostatically tested PCIVs when tested at
~ 1.10 Pa (43.73 psig). The combined leakage rates must be demonstrated in accordance with the leakage test Frequency required by the 10 CFR 50 Appendix J Testing Program Plan.
- 1.
Technical Requirements Manual.
- 2.
USAR, Section 15.6.5.
- 3.
USAR, Section 15.6.4.
- 4.
USAR, Section 15.2.4.
- 5.
10 CFR 50.36(c)(2)(ii).
- 6.
USAR, Section 6.2.4.3.2.
- 7.
10 CFR 50, Appendix J Option B.
- 8.
H21C-106, "Unit 2 LOCA w/LOOP AST Methodology" B 3.6.1.3-19 Revision 0, 3 vA.96), 44 (A152),
45 vA,156), 61 (182), 78 (201)
+
+-