L-2025-207, CFR 50.46 30-Day Report
| ML26009A089 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 01/09/2026 |
| From: | Mack K Florida Power & Light Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| L-2025-207 | |
| Download: ML26009A089 (0) | |
Text
U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-00001 Re:
St. Lucie Units 1 and 2 Docket No. 50-389 and 335 January 09, 2026 Facility License Nos. DPR-67 and NPF-16 10 CFR 50.46 30-Day Report L-2025-207 10 CFR 50.46 Pursuant to 10 CFR 50.46(a)(3)(ii), Florida Power & Light Company (FPL) is submitting a 30-day report for the emergency core cooling system (ECCS) analysis for St. Lucie Units 1 and 2. Framatome identified a minor error in the embedded fuel models within the S-RELAP5 code. The error incorrectly accounted for the transient oxidation layer thickness, leading to a slight overestimation of the cladding thermal conductivity. The conductivity error was corrected, and an evaluation was conducted to determine the impact the error has on the affected analysis.
The evaluation concluded that the error had an impact of +5°F. The Peak Clad Temperature (PCT) remains within limits and in compliance with 1 O CFR 50.46 acceptance criteria. The cumulative error for the realistic large break LOCA (RLBLOCA) is less than 50°F. The cumulative error for the small break LOCA (SBLOCA), however, is greater than 50°F therefore a 1 O CFR 50.46 report must be issued. Attachment 1 provides the updated rack-up table for St. Lucie Unit 1 and Attachment 2 provides the updated rack-up table for St. Lucie Unit 2. The evaluation of the reported error concluded that re-analysis is not required.
Should you have any questions regarding this submittal, please contact Ms. Maribel Valdez, Fleet Licensing Manager, at 561-904-5164.
Sincerely,
/(~ ~
Kenneth A. Mack Director, Licensing and Regulatory Compliance Florida Power & Light Company Attachments:
(1) St. Lucie Unit 1 Small Break LOCA PCT 30-Day Report (2) St. Lucie Unit 2 Small Break LOCA PCT 30-Day Report cc:
USNRC Regional Administrator, Region II USNRC Project Manager, St. Lucie Nuclear Plant USNRC Resident Inspector, St. Lucie Nuclear Plant Mr. Clark Eldridge, Florida Department of Health Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
L-2025-207 Page 1 of 1 St. Lucie Unit 1 Small Break LOCA PCT 30-Day Report Evaluation Methodology:
Framatome, "PWR Small Break LOCA Evaluation Model, S-RELAP5 Based," EMF-2328(P)(A)
Revision Oas supplemented by ANP-3000(P), Revision 0.
Evaluation Model PCT: 1828°F Prior 1 0 CFR 50.46 Changes or Error Corrections - up to Year 2024 (Reference 1)
Prior 10 CFR 50.46 Changes or Error Corrections - Year 2025 New 10 CFR 50.46 Changes or Error Corrections-Year 2025 I
Error in treatment of oxide layer thermal conductivity Sum of 1 0 CFR 50.46 Changes or Error Corrections The sum of the PCT from the most recent analysis using an acceptable evaluation model and the estimates of PCT impact for changes and errors identified since this analysis Error in Treatment of Oxide Layer Thermal Conductivity Net PCT Absolute PCT Effect Effect
+24°F 84 °F None None
+5°F 5°F
+29°F 89°F 1857 °F < 2200 °F Framatome identified an error in the embedded fuel models within the S-RELAP5 code. The error incorrectly accounted for the transient oxidation layer thickness when adjusting the cladding thermal conductivity, leading to a slight overestimation of the cladding thermal conductivity. The error has been corrected and an evaluation was conducted to determine the impact the error has on the affected analyses.
Reference:
- 1. Letter L-2025-024, "1 0 CFR 50.46 Annual Reporting of Changes to, or Errors in Emergency Core Cooling System Models or Applications," March 10, 2025 (Accession No. ML25069A525).
St. Lucie Unit 2 Small Break LOCA PCT 30-Day Report Evaluation Methodology:
L-2025-207 Page 1 of 1 Framatome, "PWR Small Break LOCA Evaluation Model, S-RELAP5 Based," EMF-2328(P)(A)
Revision 0.
Evaluation Model PCT: 2057°F Prior 1 O CFR 50.46 Changes or Error Corrections - up to Year 2024 (Reference 1)
Prior 10 CFR 50.46 Changes or Error Corrections-Year 2025 New 10 CFR 50.46 Changes or Error Corrections - Year 2025 I
Error in treatment of oxide layer thermal conductivity Sum of 1 O CFR 50.46 Changes or Error Corrections The sum of the PCT from the most recent analysis using an acceptable evaluation model and the estimates of PCT impact for changes and errors identified since this analysis Net PCT Absolute PCT Effect Effect
-279°F 393 °F None None
+5°F 5°F
-274°F 398°F 1783 °F < 2200 °F Error in Treatment of Oxide Layer Thermal Conductivity for S-RELAP5 Fuel Models Framatome identified an error in the embedded fuel models within the S-RELAP5 code. The error incorrectly accounted for the transient oxidation layer thickness when adjusting the cladding thermal conductivity, leading to a slight overestimation of the cladding thermal conductivity. The error has been corrected and an evaluation was conducted to determine the impact the error has on the affected analyses.
Reference:
- 1. Letter L-2025-024, "10 CFR 50.46 Annual Reporting of Changes to, or Errors in Emergency Core Cooling System Models or Applications," March 10, 2025 (Accession No. ML25069A525).