L-2015-155, Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors, 10 CFR 50.46 Change Report
| ML15149A150 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 05/14/2015 |
| From: | Katzman E Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2015-155 | |
| Download: ML15149A150 (5) | |
Text
May 14, 2015 L-2015-155 10 CFR 50.46 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Re:
St. Lucie Unit 1 Docket No. 50-335 Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors 10 CFR 50.46 Change Report The cumulative effect of small break loss of coolant accident (SBLOCA) peak cladding temperature (PCT) changes has exceeded 50'F. The recent errors are associated with the S-RELAP5 Vapor Absorption Correlation (+527F) and a change in the initial fuel rod pressurization from 390 psia to 330 psia (-30 'F) for a net temperature change of +22°F. The analysis of record PCT value increased from 1828°F to 1850'F.
According to 10 CFR 50.46, when a cumulative PCT change in errors or changes to the analysis of 50 'F occurs, a 30-day report shall be sent to the NRC in compliance with 50.46 requirements.
This inf6omation is provided in the attachment to this letter, which also includes the new evaluation model'PCTs for both SBLOCA and LBLOCA due to the imp lementiat'in of M5 fuel rod cladding.
Please contact Richard Sciscente at (772) 467-7156 should you have any questions regarding this submittal.
Sincerely,.
Eric S. Katzman Licensing Manager St. Lucie Plant.
ESK/rcs Attachment Florida Power & Light Company 6501 S. Ocean Drive, Jensen Beach, FL 34957
L-2015-155 Attachment Page 1 of 4 St. Lucie Unit 1 10 CFR 50.46 30-Day Report Emergency core cooling system (ECCS) analyses for St. Lucie Unit 1 is performed by AREVA Inc. The following 30-day report, pertaining to the application of the AREVA small break loss of coolant accident (SBLOCA) and large break loss of coolant accident (LBLOCA) evaluation models, is provided pursuant to 10CFR 50.46(a)(3)(ii). A summary of the calculated peak cladding temperature (PCT) changes is provided in Tables 1 and 2. This also serves to notify the NRC of a new evaluation model PCT being used for both SBLOCA and LBLOCA (previous evaluation model analysis pertained to Zirc-4 fuel rod cladding, while the new evaluation model analysis pertains to M5 fuel rod cladding that was implemented for Cycle 26).
1.0 ST LUCIE UNIT 1 1.1 Changes to SBLOCA New Evaluation Model PCT SBLOCA was re-analyzed for the implementation of M5 fuel rod cladding as documented in References 2.1 and 2.2. The new evaluation model PCT is 1828 'F.
S-RELAP5 Vapor Absorptivity Correlation It was determined that a correlation for vapor absorptivity used in S-RELAP5 was being applied outside of the intended range for the correlation. The impact on the SBLOCA analysis is estimated to be +52 'F.
Change for Initial Fuel Rod Pressurization A change to the initial fuel rod pressurization of 390 psia used in the new evaluation model analysis to 330 psia resulted in an estimated impact to the PCT of -30 'F.
The SBLOCA PCT, with the estimated impacts of the above errors, is 1850 'F which maintains significant margin to the limit of 2200 'F prescribed in 10 CFR 50.46. A summary of the calculated peak cladding temperature (PCT) changes (from those reported in Reference 2.1 and approved in Reference 2.2) for SBLOCA is provided in Table 1. The final PCT of 1850 'F maintain sufficient margin to the limit of 2200 'F.
1.2 Changes to LBLOCA New Evaluation Model PCT LBLOCA was re-analyzed for the implementation of M5 fuel rod cladding as documented in References 2.1 and 2.2. The new evaluation model PCT is 1788 'F.
L-2015-155 Attachment Page 2 of 4 Trapped Stack Model Associated with RODEX3a The trapped stack model in a subroutine associated with RODEX3a fuel rod model used in the S-RELAP5 analysis had erroneous coding, which resulted in an estimated impact of +6 'F to the PCT.
S-RELAP5 Vapor Absorptivity Correlation The vapor absorptivity correlation was incorrectly applied outside of the bounds of the correlation, which resulted in an estimated impact to the PCT of 0 'F.
Non-Physical Axial Shapes Generated by the Modal Decomposition Model The modal decomposition (re-mapping of neutronics nodes to S-RELAP5 node structure) resulted in non-physical axial shapes being generated in some cases. For PSL I the shapes generated still remained applicable, therefore the estimated impact to the PCT was 0 'F.
Design Change for Initial Fuel Rod Pressurization A change to the initial fuel rod pressurization of 390 psia used in the new evaluation model analysis to 330 psia resulted in an estimated impact to the PCT of 0 'F The LBLOCA PCT, with the estimated impacts of the above errors, is 1794 'F which maintains significant margin to the limit of 2200 'F prescribed in 10 CFR 50.46. A summary of the calculated peak cladding temperature (PCT) changes (from those reported in Reference 2.1 and approved in Reference 2.2) for LBLOCA is provided in Table 2. The final PCT of 1794 'F maintains sufficient margin to the limit of 2200 'F.
2.0 REFERENCES
2.1 FPL Letter L-2013-139, Joseph Jensen to U.S. Nuclear Regulatory Commission Document Control Desk, "St. Lucie Unit 1 Docket No. 50-335, Application for Technical Specification Change and Exemption Request Regarding the Use of M5 Alloy Fuel Cladding in Core Reload Applications," May 10, 2013 (ADAMS accession No. ML13135A008).
2.2 NRC Letter "St. Lucie Plant, Unit 1 - Issuance of Amendment Regarding the use of M5 Alloy Fuel Cladding in Core Reload Applications (TAC No. MF 1817)," dated March 31, 2014.
L-2015-155 Attachment Page 3 of 4 Table 1: St. Lucie Unit 1 SBLOCA Margin Summary Sheet day Report (May 2015)
Old Evaluation Model: EMF-2328(P)(A) Rev. 0 as supplemented by ANP-3000(P), Revision 0.
New Evaluation Model: EMF-2328(P)(A) Rev. 0 as supplemented by ANP-3000(P), Revision 0.
New Evaluation Model PCT: 1828'F Net PCT Effect Absolute PCT Effect PCT 10 CFR 50.46 Changes Since New Evaluation Model PCT S-RELAP5 Vapor Absorptivity
+52 OF 52 OF 1880 OF Correlation Error Design Change for Initial Pressurization of Fuel Rod E
B Sum of 10 CFR 50.46 Changes
+22 OF 82 OF The sum of the PCT from the most recent analysis using an acceptable evaluation model and the 1850 OF <2200 OF estimates of PCT impact for changes and errors identified since this analysis
L-2015-155 Attachment Page 4 of 4 Table 2: St. Lucie Unit 1 LBLOCA Margin Summary Sheet day Report (May 2015)
Old Evaluation Model: EMF-2103(P)(A) Rev. 0 as supplemented by ANP-2903(P), Revision 1.
New Evaluation Model: EMF-2103(P)(A) Rev. 0 as supplemented by ANP-2903(P), Revision 1.
New Evaluation Model PCT: 1788 0F Net PCT Effect Absolute PCT Effect PCT 10 CFR 50.46 Changes Since New Evaluation Model PCT S-RELAP5 RODEX3a Trapped
+6 OF 6 OF 1794 OF Stack Coding Error S-RELAP5 Vapor Absorptivity 0 OF 0 OF 1794 OF Correlation Error Modal Decomposition Generation of 0 OF 0 OF 1794 OF Non-Physical Shapes Design Change for Initial Pressurization of Fuel Rod B
Sum of 10 CFR 50.46 Changes
+6 OF 6 OF The sum of the PCT from the most recent analysis using an acceptable evaluation model and the 1794 OF <2200 OF estimates of PCT impact for changes and errors identified since this analysis