NRC-08-0003, Day 10 CFR 50.46 Report, Plant Specific ECCS Evaluation Changes

Day 10 CFR 50.46 Report, Plant Specific ECCS Evaluation Changes

ML080230463
Person / Time
Site:	Fermi
Issue date:	01/16/2008
From:	Plona J DTE Energy
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NRC-08-0003
Download: ML080230463 (9)

Text

Joseph H. Plona Site Vice President 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.5910 Fax: 734.586.4172 DTE Energy-10 CFR 50.46 January 16, 2008 NRC-08-0003 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001

References:

1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43

2) Detroit Edison Letter to USNRC, "2006 Annual Reports for Fermi 2," dated April 24, 2007 (NRC-07-0019)

3) General Electric "10 CFR 50.46 Notification Letter 2006-01," dated July 28, 2006

4) Detroit Edison Letter to USNRC, "30-Day 10 CFR 50.46 Report, Plant Specific ECCS Evaluation Changes," dated July 3, 2007 (NRC-07-0038)

5) General Electric "10 CFR 50.46 Notification Letter 2007-01," dated December 18, 2007

'3

Subject:

30-Day 10 CFR 50.46 Report, Plant Specific ECCS Evaluation Changes In accordance with 10 CFR 50.46(a)(3)(ii), this letter reports model changes or errors in the General Electric (GE) Plant Specific Emergency Core Cooling System (ECCS) evaluation for Fermi 2. General Electric (GE) and Global Nuclear Fuel (GNF) issued GE Notification Letter 2007-01 (Reference 5) which indicates that a change has been made in the small break ECCS-loss. of coolant accident (LOCA) analyses.

Specifically, it has been found that Division I Battery failure, which causes the loss of Automatic Depressurization System (ADS), is the limiting single failure with

USNRC NRC-08-0003 Page 2 respect to Licensing Basis Peak Clad Temperature (LBPCT). This case had previously been assumed to be bounded by the Division II Battery failure which causes the loss of High Pressure Coolant Injection (HPCI) capability. The change discussed in Reference 5 requires the performance of the small break analysis to consider that all ADS valves for Fermi 2 rely on the Division I Battery for electricity.

Division I Battery failure has always been a candidate failure for the analysis, though only relevant to small break LOCA scenarios that depend on ADS availability to depressurize the vessel. It had been considered in prior analyses and was erroneously concluded to be non-limiting when compared to Division II Battery failure in conjunction with a 0.15 sq. ft recirculation line break. LBPCT was determined historically on the basis of limiting Design Basis Accident (DBA) large breaks.

However, the current analysis for Fermi 2 had revealed small breaks as the limiting cases for LBPCT for GE14 fuel.

Analyses have been performed of the small break LOCA scenario for Fermi 2 under the assumption that the Division I Battery fails. The results are reported for fuel types currently resident in the core. For GEl4 fuel, the current LBPCT is based on a limiting small break case. The result of the analysis shows a direct addition to LBPCT that needs to be applied to account for the single failure of the Division I Battery becoming limiting. For GEl 1 fuel, the current LBPCT is based on a limiting DBA (large) break case. The effect of this change, applying the single failure of the Division I Battery to the current small break case result, makes the GEl 1 analysis small break limiting, as well. To this small break result, the effect of top-peaked power distribution, as reported in GE Notification Letter 2006-01 (Reference 3),

must also be applied. The reported Change in Calculated Peak Cladding Temperature is the net change in LBPCT.

Reference 5 indicates that the Fermi 2 peak cladding temperature (PCT) has increased by 105lF for GEl 1 fuel, and has increased by 255°F for GEl4 fuel. The PCT increases apply to the small break LOCA only. A special report is required in accordance with 10 CFR 50.46(a)(3)(ii) in addition to the annual report of methodology changes. Incorporating the changes in PCT in accordance with Reference 5, the PCT is 1696°F for the GEl 1 fuel in the Fermi 2 core, and has increased to 1930'F for the GEl4 fuel in the core. This results in a 270'F margin to the 2200'F PCT limit in 10 CFR 50.46. provides updated information regarding the PCT for the limiting LOCA analysis evaluations and detailed assessment for each model change or error reported for Fermi 2.

Detroit Edison plans to reanalyze the SAFERIGESTR-LOCA Loss-of-Coolant Accident Analysis for Fermi 2 due to the discovered error. Reanalysis of the SAFER/GESTR-LOCA Loss-of-Coolant Accident will be provided by June 30, 2008.

USNRC NRC-08-0003 Page 3 Detroit Edison will continue to track future methodology changes and errors in the SAFER/GESTR-LOCA Loss-of-Coolant Accident Analysis evaluation models to ensure that the analyzed PCT remains below the 10 CFR 50.46 limits, and to ensure that the 10 CFR 50.46 reporting requirements are met. contains a summary of regulatory commitments associated with this letter.

Should you have any questions or require additional information, please contact Mr.

Ronald W. Gaston of my staff at (734) 586-5197.

Sincerely,

Enclosures:

1. Peak Cladding Temperature Analysis Update and Assessment of Model Changes

2. Summary of Regulatory Commitments cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 4, Region I11 Regional Administrator, Region HI Supervisor, Electric Operators, Michigan Public Service Commission

ENCLOSURE 1 TO NRC-08-0003 PEAK CLADDING TEMPERATURE ANALYSIS UPDATE AND ASSESSMENT OF MODEL CHANGES to NRC-08-0003 Page 1 Plant Name: Fermi 2 Power Plant ECCS Evaluation Model: SAFER/GESTR-LOCA Report Revision Date: 01/16/2008 Current Operating Cycle: 13 ANALYSIS OF RECORD Evaluation Model:

1. NEDC-23785-1-PA Rev. 1, "The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume II, SAFER-Long Term Inventory Model for BWR Loss-Of-Coolant Analysis," October 1984.

2. NEDC-30996P-A, "SAFER Model for Evaluation of Loss-of-Coolant Accidents for Jet Pump and Non-jet Pump Plants, Volume I, SAFER-Long Term Inventory Model for BWR Loss-of-Coolant Analysis," October 1987.

3. NEDC-32950P, "Compilation of Improvements to GENE's SAFER ECCS-LOCA Evaluation Model," January 2000.

4. NEDC-23785-1-PA Rev. 1, "The GESTR-LOCA and SAFER Models for the Evaluation of the Loss-Of-Coolant Accident Volume II, SAFER/GESTR Application Methodology,"

October 1984. (Jet Pump Plant-SAFER)

Calculations:

1. "DTE Energy Enrico Fermi 2 SAFER/GESTR Loss of Coolant Accident Analysis for GE14 Fuel," GE-NE-0000-0030-6565-RO, dated September 2004.

2. "DTE Energy Enrico Fermi 2 SAFER/GESTR Loss of Coolant Accident Analysis for GE 1I Fuel," GE-NE-0000-0047-1716-RO, dated December 2005.

Fuel Analyzed in Calculations: GEl 1 and GEl4 Limiting Fuel Type for Original Analyses: GEl 1 Limiting Single Failure for Original Analyses: Division II Battery Power Limiting Break Size and Location for Original Analyses: Double Ended Guillotine in a Recirculation Suction Pipe Reference LBPCT for Original Analyses: 1650'F for GEl 1 Fuel to NRC-08-0003 Page 2 MARGIN ALLOCATION Prior LOCA Model Assessments for GEll and GE14 Fuel GE14 GEl1 NRC-06-0016 dated March 16, 2006 (See Note 1) APCT = 00 F APCT = 0°F NRC-07-0019 dated April 24, 2007 (See Note 1) APCT = 0°F APCT = 0°F NRC-07-0038 dated July 3, 2007 (See Note 2) APCT = 55°F APCT = 0°F Net PCT 1675 0F* 1650°F**

Current LOCA Model Assessment for GEll and GE14 Fuel GE14 GEl1 10 CFR 50.46 Notification Letter dated December APCT = 255 0 F APCT = 105'F 18, 2007, Division I Battery Failure and ADS Impact for Small Break LOCA Analysis (See Note 3)

Net PCT 1930OF* 1696 0F*

• Small break LOCA is limiting.

• • Large break LOCA is limiting.

Notes of LOCA Model Assessments for GEll and GE14 Fuel

1. The referenced letter provided the annual 50.46 report for Fermi 2. There were no errors reported for the 2005 and 2006 reporting periods.

2. The referenced letter provided a 30 day report on GE LOCA errors. GE reported that the small break ECCS-LOCA analyses have assumed a mid-peaked power shape, consistent with DBA break LOCA analyses. GE determined that for small break cases, a top-peaked axial power shape can result in higher peak cladding temperature. Evaluations were performed on representative BWR plant types. The impact on the Fermi licensing basis peak cladding temperature was 55°F for the small break LOCA only. The large break LOCA was unaffected by the error.

For GE14, since the small break LOCA was already limiting, the GE14 PCT was raised by 55 0 F from 1620'F to 1675°F. The GEl 1 large break LOCA was limiting prior to the error but was changed to be 25°F lower. The Limiting LOCA was considered to be the GE14 Division II Battery failure with a 0.15 sq. ft break size.

,Enclosure 1 to NRC-08-0003 Page 3 For GEl 1, the small break LOCA PCT was raised from 1536°F to 1591°F with the 55 0 F error. The small break LOCA remained non-limiting for GEl 1 fuel. Therefore, the large break LOCA PCT was reported for GEl 1 fuel in Reference 4 and remained unchanged from the original LOCA evaluation cited in Enclosure 1.

3. GE Notification Letter 2007-01 affects the small break LOCA only; however, it causes the small break LOCA to be the limiting case for both GEl 1 and GE14 fuel. Both GEl 1 and GEl4 are impacted with a 255°F error on GEl4 fuel and 105'F error on GEl 1 fuel. For GE14, since the small break LOCA was already limiting, the GEl4 PCT was raised by 255°F from 1675°F to 1930'F. The Limiting LOCA changes from the Division II Battery failure with a 0.15 sq. ft break size to the Division I Battery failure small break.

For GE 11, the large break LOCA was reported as limiting in Reference 4 at 1650°F with the small breakLOCA PCT at 1591 F after accounting for the 55°F error reported in Reference

3. With the issuance of Reference 5, the GEl 1 limiting LOCA PCT has switched from the large break at 1650°F to the small break LOCA. The small break LOCA PCT was raised from 1591°F to 1696°F with the 105'F error reported in Reference 5. The small break LOCA became limiting for GEl 1 fuel and the Limiting GEl4 LOCA changes from the Division II Battery failure with a 0.15 sq. ft break size to the Division I Battery failure small break.

ENCLOSURE 2 TO NRC-08-0003

SUMMARY

OF REGULATORY COMMITMENTS

Wnclosure 2 to NRC-08-0003 Page 1

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies the action committed to by Detroit Edison in this document. Any other statements in this submittal are provided for information purpose and are not considered to be regulatory commitments. Please direct questions regarding the commitment to Ronald W.

Gaston, Manager - Nuclear Licensing, at (734) 586-5197.

REGULATORY COMMITMENT DUE DATE

1. Detroit Edison commits to provide a To be provided by June 30, 2008.

reanalysis of the SAFER/GESTR-LOCA Loss-of-Coolant Accident to the NRC.