ML051120295

Annual Report for 2004 Loss of Coolant Accident (Loca)/Emergency Core Cooling System (ECCS) Models Pursuant to 10 CFR 50.46

ML051120295
Person / Time
Site:	Fort Calhoun
Issue date:	04/22/2005
From:	Phelps R Omaha Public Power District
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LIC-05 -0045
Download: ML051120295 (5)

Text

444 South 16th Street Mall Omaha NE 68102-2247 April 22,2005 LIC-05-0045 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555

References:

1. Docket 50-285

2. XN-NF-82-49(P)(A), Supplement 1, Exxon Nuclear Company Evaluation Model Revised EXEM PWR Small Break Model, Revision 1, December 1994

3. EMF-2087(P)(A), SEM/PWR-98: ECCS Evaluation Model for PWR LBLOCA Applications, Revision 0, June 1999

4. Letter from OPPD (R. T. Ridenoure) to NRC (Document Control Desk), Annual Report for 2003 Loss of Coolant Accident (LOCA) /Emergency Core Cooling System (ECCS) Models Pursuant to 10 CFR 50.46, dated April 30,2004 (LIC-04-0058)

Subject:

Annual report for 2004 Loss of Coolant Accident (LOCA)/Emergency Core Cooling System (ECCS) Models Pursuant to 10 CFR 50.46 In accordance with 10 CFR 50(46)(a)(3)(ii), the Omaha Public Power District (OPPD) is submitting the annual 10 CFR 50.46 summary report for 2004. This summary report updates all identified changes or errors in the LOCNECCS codes, methods, and applications used by AREVA (formerly Framatome ANP) to model Fort Calhoun Station, Unit No. 1 (FCS). References 2 and 3, respectively, describe the Small Break (SB) and Large Break (LB) LOCA analysis methodology used by AREVA for the FCS Analysis of Record.

OPPD has received 2004 AREVA 10 CFR 50.46 Annual Notification Report for the SB and LB LOCA Analyses that are subject to the reporting requirements of 10 CFR 50.46.

For 2004, there were no Small Break LOCA Analysis Peak Clad Temperature (PCT) 10 CFR Model Assessment errors. Attachment 1 provides the 2004 Small Break Peak Clad Temperature Margin Utilization Summary for FCS, which is unchanged from the 2003 Annual Report (Reference 4). The value of the PCT remains at 1864 OF.

For 2004, there was one Large Break LOCA Analysis PCT 10 CFR 50.46 Model Assessment error of -2 OF as described in Attachment 2, due to loss coefficient mismatch Employment with Equal Opportunity 4171

U. S. Nuclear Regulatory Commission LIC-05-0045 Page 2 between RELAP4 and RFPACmFLEX. Attachment 3 provides the 2004 Large Break LOCA Peak Clad Temperature Margin Utilization summary for Fort Calhoun Station.

As a result of this error, the Large Break LOCA PCT changed from Reference 4 value of 1956 OF to 1954 OF.

In summary, the FCS PCT values for Small and Large Break LOCA remain less than 10 CFR 50.46(b) (1) acceptance criteria of 2200 OF.

If you should have any questions, please contact Tom Matthews at (402) 533-6938. No commitments are made to the NRC in this letter.

R. L. Phelps Division Manager Nuclear Engineering Attachments:

1. Fort Calhoun Station Small Break LOCA Peak Clad Temperature Margin Utilization Summary

2. 10 CFR 50.46 Large Break LOCA Model Assessment

3. Fort Calhoun Station Large Break LOCA Peak Clad Temperature Margin Utilization Summary.

LIC-05-0045 Fort Calhoun Station Small Break LOCA Peak Clad Temperature Margin Utilization Summary LICENSING BASIS Clad Temperature (OF)

Analysis of Record 1865 MARGIN ALLOCATIONS (APCT)

A. Prior Permanent ECCS Model Assessments -1 B. 2004 10 CFR 50.46 Model Assessments 0 (Permanent Assessments of PCT Margin)

LICENSING BASIS PCT + MARGIN ALLOCATIONS 1864

LIC-05-0045 10 CFR 50.46 Large Break LOCA Model Assessments Inconsistent Loss coefficients between RELAP4 and RFPAC/REFLEX In response to a condition report, AREVA (formerly Framatome) reviewed the Fort Calhoun Station Unit No. 1 Large Break LOCA analysis inputs. This review revealed that there was one loss coefficient mismatch between RELAP4 and RFPAC/REFLEX codes used in the FCS Large Break LOCA analysis. The mismatch is that the break loop cold leg to vessel inlet loss coefficient in RELAP4 is not included with the vessel-side break loss coefficient in the RFPAUREFLEX input.

For this evaluation, the limiting case (double ended cold leg guillotine break with a 0.8 discharge coefficient, EOC axial power shape, MOC stored energy and the loss of one LPSI pump) from the Cycle 21 analysis was rerun after correcting the RFPAUREFLEX loss coefficient mismatch. PCT for the new calculation was then compared to the PCT reported in the Cycle 21 analysis to determine the change in PCT due to the mismatch in loss coefficients.

Comparing the results of the new calculation with the results from the Cycle 21 analysis limiting case value shows that the PCT changed from 1956 OF to 1954 OF. Therefore, the result of the calculation shows that the 10 CFR 50.46 impact is -2 O F for FCS.

LIC-05-0045 Fort Calhoun Station Large Break LOCA Peak Clad Temperature Margin Utilization Summary LICENSING BASIS Clad Temperature (OF)

Analysis of Record 1956 MARGIN ALLOCATIONS (APCT)

A. Prior Permanent ECCS Model Assessments 0 C. 2004 10 CFR 50.46 Model Assessments -2 (Permanent Assessments of PCT Margin)

LICENSING BASIS PCT + MARGIN ALLOCATIONS 1954