ML25113A202
| ML25113A202 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/22/2025 |
| From: | James Holloway Dominion Energy, Dominion Energy Nuclear Connecticut |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 24-347 | |
| Download: ML25113A202 (1) | |
Text
Dominion Energy Nuclear Connecticut, !nc.
5000 Dominion Boulevard, Glen Allen, VA 23060 DominionEnergy.com April 22, 2025 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 DOMINION ENERGY NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 Serial No.
NRA/NDM:
Docket No.
License No.
Dominion Energy '24-347 RO 50-423 NPF-49 APPLICATION TO REVISE TECHNICAL SPECIFICATIONS TO ADOPT TSTF-577, "REVISED FREQUENCIES FOR STEAM GENERATOR TUBE INSPECTIONS,"
USING THE CONSOLIDATED LINE-ITEM IMPROVEMENT PROCESS Pursuant to 10 CFR 50.90, Dominion Energy Nuclear Connecticut, Inc. (DENG) is submitting a license amendment request (LAR) to the Nuclear Regulatory Commission (NRC) to revise the Technical Specifications (TS) for Millstone Power Station Unit 3 (MPS3).
DENG requests adoption of TSTF-577, "Revised Frequencies for Steam Generator Tube Inspections," which is an approved change to the Standard Technical Specifications (STS), into the MPS3 TS. The TS related to steam generator (SG) tube inspections and reporting are revised based on operating history. to this letter describes the proposed changes and the requested confirmation of applicability. Attachment 2 provides marked-up MPS3 TS pages showing the proposed changes. The TS Bases are not affected by the proposed changes.
DENG requests that the amendment be reviewed under the Consolidated Line Item Improvement Process (CLIIP). Approval of the proposed amendment is requested within 6 months of completion of the NRC's acceptance review. Once approved, the amendment shall be implemented within 60 days.
The proposed amendment has been reviewed and approved by the station's Facility Safety Review Committee.
In accordance with 10 CFR 50.91 (b), a copy of this LAR is being provided to the State of Connecticut.
Serial No.24-347 Docket No. 50-423 Page 2 of 3 If you have any questions or require additional information, please contact Mr. Nick Maynard at (804) 273-3910.
Sincerely, James Holloway Vice President-Nuclear Engineering and Fleet Support COMMONWEAL TH OF VIRGINIA COUNTY OF HENRICO The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by James Holloway, who is Vice President - Nuclear Engineering and Fleet Support of Dominion Energy Nuclear Connecticut, Inc. He has affirmed before me that he is duly authorized to execute and file the foregoing document on behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
Acknowledged before me this 22.- day of A(Pv-i \\
My Commission Expires:
C\\--?>0-2021 JULIE H HOUGH NOTARY PUBLIC 8066994 COMMONWEALTH OF VIRGINIA MY COMMISSION EXPIRES 09-30-2027 Attachments:
, 2025.
l ~
~NotaryPub"c
- 1. Description and Assessment of Proposed Change
- 2. Marked-up Technical Specification Pages Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region I 475 Allendale Rd., Suite 102 King of Prussia, PA 19406-1415 Richard V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 9 E3 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Millstone Power Station Director, Radiation Division Department of Energy and Environmental Protection 79 Elm Street Hartford, CT 06106-5127 Serial No.24-347 Docket No. 50-423 Page 3 of 3
Serial No.24-347 Docket Nos. 50-423 DESCRIPTION AND ASSESSMENT OF PROPOSED CHANGE Dominion Energy Nuclear Connecticut, Inc.
Millstone Power Station Unit 3
Serial No.24-347 Docket No. 50-423, Page 1 of 5
1.0 DESCRIPTION
Pursuant to 10 CFR 50.90, Dominion Energy Nuclear Connecticut, Inc. (DENC) proposes changes to the Millstone Power Station Unit 3 (MPS3) Technical Specifications (TS) to adopt Technical Specifications Task Force (TSTF) Traveler TSTF-577, Revision 1, "Revised Frequencies for Steam Generator Tube Inspections." The TS related to steam generator (SG) tube inspections and reporting are revised based on operating history.
The proposed change revises the TS related to SG tube inspections and reporting requirements in TS section 6.8.4.g, Steam Generator (SG) Program, and TS section 6.9.1.7, Steam Generator Tube Inspection Report, respectively. Specifically, TS 6.8.4.g is being revised to define a new, fixed SG tube inspection frequency of at least every 54 effective full power months (EFPMs) and to delete various inspection period requirements. The new inspection period starts after a 100% inspection of all SG tubes has been performed during a single outage (past or future). The current TS requirement to perform an inspection after a crack is found within 24 effective full power months or one refueling outage (whichever results in more frequent inspections) is also being revised to require an inspection during the next refueling outage but may be deferred to the following refueling outage if the 100% inspection of all SGs was performed with enhanced probes. Finally, the proposed change rearranges the existing reporting requirements in TS 6.9.1.7 for clarity.
2.0 ASSESSMENT
2.1 Applicability of Safety Evaluation DENC has reviewed the safety evaluation for TSTF-577 provided to the TSTF in a letter dated April 14, 2021 (ADAMS Package No. ML21099A086). This review included a review of the NRC staffs evaluation, as well as the information provided in TSTF-577. As described herein, DENC has concluded the justifications presented in TSTF-577 and the safety evaluation prepared by the NRC staff are applicable to MPS3 and justify this amendment for the incorporation of the changes into the MPS3 TS.
The current MPS3 SG TS requirements are based on TSTF-510, "Revision to Steam Generator Program Inspection Frequencies and Tube Sample Selection." The MPS3 SGs have Alloy 600 thermally treated (Alloy 600TT) tubes. The initial inspection period described in the SG Program, paragraph 6.8.4.g.d.2, began when the 100% SG inspection was completed for MPS3 during the Fall 2023 refueling outage (RFO). DENC will submit a SG Tube Inspection Report meeting the revised TS 6.9.1.7 requirements within 30 days after implementation of the license amendment.
Serial No.24-347 Docket No. 50-423, Page 2 of 5 2.2 Variations DENC is proposing the following variations from the TS changes described in TSTF-577 or the applicable parts of the NRC staffs safety evaluation dated April 14, 2021 (ADAMS Package No. ML21099A086).
The MPS3 TS are organized differently and use a different numbering format than the Standard Technical Specifications (STS) on which TSTF-577 was based.
Specifically, the numbering differences are:
TSTF-577, Rev. 1, Westinghouse Owners Group (WOG) STS Corresponding MPS3 TS 5.5.9, Steam Generator (SG)
Program 6.8.4.g 5.6.7, Steam Generator Tube Inspection Report 6.9.1.7 3.4.13, RCS Operational LEAKAGE 3.4.6.2 These differences are administrative and do not affect the applicability of TSTF-577 to the MPS3 TS.
MPS3 TS 6.9.1.7 is revised to place the title of TS 6.8.4.g in quotes. This change is administrative and is consistent with TSTF-577.
The MPS3 SG Program TS currently contains a provision for an alternate tube plugging criteria (TS 6.8.4.g.c). The description of the alternate tube plugging criteria in the proposed change is equivalent to the description in the current TS.
Therefore, TSTF-577 is still applicable.
The MPS3 TS contain requirements related to alternate tube plugging that differ from the Standard Technical Specifications on which TSTF-577 was based.
Specifically, MPS3 TS 6.8.4.g.c currently states, in part: "The following alternate tube plugging criteria shall be applied as an alternative to the 40% depth-based criteria:", whereas TSTF-577-A states: "The following alternate tube plugging [or repair] criteria may be applied as an alternative to the 40% depth-based criteria:"
(emphasis added).
The alternate tube repair criteria sentence including the word "may" was added to TS 5.5.9.c of the WOG STS with TSTF-449-A, Revision 4, "Steam Generator Tube Integrity," dated April 14, 2005 (ADAMS Accession No. ML051090200). MPS3 implemented TSTF-449-A in Amendment 238, dated May 31, 2007; however,
Serial No.24-347 Docket No. 50-423, Page 3 of 5 MPS3 did not have alternate tubing repair criteria at that time, so the subject sentence wasnt included. The shall wording was subsequently included in the MPS3 TS by Amendment 256 for MPS3, dated January 11, 2013, when interim alternate repair criteria were included in the MPS3 SG inspection program requirements and TSTF-510-A, Revision 0, "Revision to Steam Generator Program Inspection Frequencies and Tube Sample Selection" (ADAMS Accession No. ML090890367) was adopted. Since the alternate tube plugging criteria are an alternative to the 40% tube plugging criterion, the word may is the proper word to use. Consequently, this request proposes changing the word "shall" to "may" in MPS3 TS 6.8.4.g.c, which aligns with the wording in TSTF-577. Therefore, TSTF-577 is still applicable.
The MPS3 TS contain requirements related to limits on leakage rates that differ from the Standard Technical Specifications on which TSTF-577 was based.
Specifically, the last sentence of MPS3 TS 6.8.4.g.b.2 states, "Leakage is not to exceed 500 gpd per SG" rather than "Leakage is not to exceed 1 gpm per SG."
The MPS3 TS requirement for leakage rate is more conservative and is therefore acceptable. A similar variation was approved for North Anna Power Station Unit Nos. 1 and 2 in Amendment Nos. 292 and 275, respectively (ADAMS Accession No. ML22068A071).
3.0 REGULATORY ANALYSIS
3.1 No Significant Hazards Consideration Analysis Dominion Energy Nuclear Connecticut, Inc. (DENC) requests adoption of TSTF 577, "Revised Frequencies for Steam Generator Tube Inspections," which is an approved change to the Standard Technical Specifications (STS), for Millstone Power Station Unit 3 (MPS3). The Technical Specifications (TS) related to steam generator (SG) tube inspections and reporting are revised based on operating history.
DENC has evaluated if 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:
- 1. Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The SG inspections are conducted as part of the SG Program to ensure and demonstrate that performance criteria for tube
Serial No.24-347 Docket No. 50-423, Page 4 of 5 structural integrity and accident leakage integrity are met. These performance criteria are consistent with the plant design and licensing basis. With the proposed changes to the inspection frequencies, the SG Program must still demonstrate that the performance criteria are met. As a result, the probability of any accident previously evaluated is not significantly increased and the consequences of any accident previously evaluated are not significantly increased.
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The proposed change does not alter the design function or operation of the SGs or the ability of an SG to perform the design function. The SG tubes continue to be required to meet the SG Program performance criteria. The proposed change does not create the possibility of a new or different kind of accident due to credible new failure mechanisms, malfunctions, or accident initiators that are not considered in the design and licensing bases.
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 amendment involve a significant reduction in a margin of safety?
Response: No.
The proposed change revises the inspection frequencies for SG tube inspections and associated reporting requirements. The proposed change does not change any of the controlling values of parameters used to avoid exceeding regulatory or licensing limits. The proposed change does not affect a design basis or safety limit, or any controlling value for a parameter established in the Final Safety Analysis Report (FSAR) or the license.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, DENC concludes 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.
Serial No.24-347 Docket No. 50-423, Page 5 of 5 3.2 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 amendments will not be inimical to the common defense and security or to the health and safety of the public.
4.0 ENVIRONMENTAL EVALUATION 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.
Serial No.24-347 Docket No. 50-423 MARKED-UP TECHNICAL SPECIFICATIONS PAGES Dominion Energy Nuclear Connecticut, Inc.
Millstone Power Station Unit 3
Serial No.24-347 Docket No. 50-423, Page 1 of 8
Serial No.24-347 Docket No. 50-423, Page 2 of 8
Serial No.24-347 Docket No. 50-423, Page 3 of 8
Serial No.24-347 Docket No. 50-423, Page 4 of 8
Serial No.24-347 Docket No. 50-423, Page 5 of 8
Serial No.24-347 Docket No. 50-423, Page 6 of 8
Serial No.24-347 Docket No. 50-423, Page 7 of 8 INSERT 1 After the first refueling outage following SG installation, inspect 100% of the tubes in each SG at least every 54 effective full power months, which defines the inspection period. If none of the SG tubes have ever experienced cracking other than in regions that are exempt from inspection by alternate repair criteria and the SG inspection was performed with enhanced probes, the inspection period may be extended to 72 effective full power months. Enhanced probes have a capability to detect flaws of any type equivalent to or better than array probe technology. The enhanced probes shall be used from the tube-to-tubesheet weld at the tube inlet to the tube-to-tubesheet weld at the tube outlet except any portions of the tube that are exempt from inspection by alternate repair criteria. If there are regions where enhanced probes cannot be used, the tube inspection techniques shall be capable of detecting all forms of existing and potential degradation in that region.*
Serial No.24-347 Docket No. 50-423, Page 8 of 8 INSERT 2 b.
The nondestructive examination techniques utilized for tubes with increased degradation susceptibility; c.
For each degradation mechanism found:
- 1. The nondestructive examination techniques utilized;
- 2. The location, orientation (if linear), measured size (if available), and voltage response for each indication. For tube wear at support structures less than 20 percent through-wall, only the total number of indications needs to be reported;
- 3. A description of the condition monitoring assessment and results, including the margin to the tube integrity performance criteria and comparison with the margin predicted to exist at the inspection by the previous forward-looking tube integrity assessment; and
- 4. The number of tubes plugged during the inspection outage.
d.
An analysis summary of the tube integrity conditions predicted to exist at the next scheduled inspection (the forward-looking tube integrity assessment) relative to the applicable performance criteria, including the analysis methodology, inputs, and results;