TMI-10-084, 10 CFR 50.46 30-Day Report Re Results of the Most Recent Small Break LOCA Analysis
| ML102500300 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/07/2010 |
| From: | Cowan P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| TMI-10-084 | |
| Download: ML102500300 (6) | |
Text
Exelon Nuclear 200 Exe]on Way Kennett Square, PA 19348 TMI-10-084 September 7,2010 www.exeloncorp.com Exelon.
Nuclear 10 CFR 50.46 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289
Subject:
References:
10 CFR 50.46 30-Day Report 1)
Letter from David P. Helker (Exelon Generation Company, LLC) to U.S.
Nuclear Regulatory Commission, "10 CFR 50.46 Report," dated May 14, 2010 2)
Letter from G. A. Thomas (AREVA) to R. Jaffa (Exelon Generation Company, LLC), "10 CFR 50.46 LOCA Report of EM Error Correction (AREVA CR 2010-4150: EOC SBLOCA axial power shape)," dated August 20,2010 The purpose of this letter is to submit a 30-day 10 CFR 50.46 report for Three Mile Island Nuclear Station (TMI), Unit 1. The most recent annual 50.46 Report for TMI, Unit 1 (Reference
- 1) provided the cumulative Peak Cladding Temperature (PCT) errors for the most recent fuel designs. This report provided the results of the most recent small break LOCA (SBLOCA) analysis. The peak clad temperature (PCT) reported for the SBLOCA was 1444°F.
Subsequent to the issuance of Reference 1, AREVA notified Exelon Generation Company, LLC (Exelon) of an Evaluation Model (EM) error correction in the Reference 2 letter. This EM error only affects SBLOCA and the error relates to the assumption of axial power shape. The axial power shape assumed by AREVA in the SBLOCA analysis in support of TMI, Unit 1 was determined to be not bounding from middle to end-of-cycle (MOC to EOC) conditions. As a result, AREVA developed a bounding axial power shape which conservatively meets all 10 CFR 50.46 requirements, and it resulted in an increase in the reported SBLOCA peak clad temperature (PCT).
10 CFR 50.46 30-Day Report September 7, 2010 Page 2 The PCT is estimated to increase by 225°F from that reported in Reference 1, resulting in an estimated PCT of (1444°F + 225°F) 1669°F for the limiting fuel type. This revised PCT of 1669°F remains well within the NRC 10 CFR 50.46 acceptance criteria of 2200°F. Additionally, the licensing basis SBLOCA analyses for TMI, Unit 1 have been performed at a power level of 2827 MWt (to support future power uprate) which represents a power uprate of 7.9% over the current licensed power level of 2619 MWt (considering uncertainty). The PCT increase was developed at an uprated power level, and would be largely negated if the plant was analyzed at the current licensed power level. The large break LOCA is not affected by this axial power shape issue.
Two attachments are included with this letter that provide the current TMI, Unit 1, 10 CFR 50.46 status. Attachment 1 ("Peak Cladding Temperature Rack-Up Sheet") provides updated information regarding the PCT for the limiting SBLOCA analyses. Attachment 2, "Assessment Notes," contains a detailed description for each change or error reported.
No new regulatory commitments are established in this submittal. If any additional information is needed, please contact Tom Loomis at (610) 765-5510.
Respectfully,
~(fj:aVj Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments:
1)
Peak Cladding Temperature Rack-Up Sheet 2)
Assessment Notes cc:
USNRC Region I, Regional Administrator USNRC Project Manager, TMI, Unit 1 USNRC Senior Resident Inspector, TMI, Unit 1
ATTACHMENT 1 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments Assessments as of September 7, 2010 Peak Cladding Temperature Rack-Up Sheet TMI, Unit 1
30-Day Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of September 7,2010 Peak Cladding Temperature Rack-Up Sheet Page 1 of 1 PLANT NAME:
ECCS EVALUATION MODEL:
REPORT REVISION DATE:
CURRENT OPERATING CYCLE:
ANALYSIS OF RECORD Three Mile Island Nuclear Station, Unit 1 Small Break Loss of Coolant Accident (SBLOCA) 9/7/10 1J!
Evaluation Model: BWNT 1
Calculation: AREVA NP, 86-9111507-000, August 2009 (Mark-B-HTP with EOTSGs)
Fuel: Mark-B12, Mark-B-HTP Limiting Fuel Type: Mark-B-HTP Limiting Single Failure: Loss of One Train of ECCS Limiting Break Size and Location: 0.07 fe Break in Cold Leg Pump Discharge Piping Reference Peak Cladding Temperature (PCT)
MARGIN ALLOCATION A. PRIOR LOSS OF COOLANT ACCIDENT (LOCA) MODEL ASSESSMENTS CFR 50.46 Report dated Ma 14,2010 (see Note 1, Attachment 2)
NET PCT B. CURRENT LOCA MODEL ASSESSMENTS Small Break Axial Power Shape (see Note 2, Attachment 2)
NETPCT 1 The BWNT EM is based on RELAP5/MOD2-B&W.
ATTACHMENT 2 10 CFR 50.46 "Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors" Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments Assessments as of September 7, 2010 Peak Cladding Temperature Rack-Up Sheet TMI, Unit 1 Assessment Notes
30-Day Report of the Emergency Core Cooling System Evaluation Model Changes and Errors Assessments as of September 7, 2010 Assessment Notes 1.
Prior LOCA Model Assessment Page 1 of 1 The 10 CFR 50.46 report dated May 14, 2010, identified a new SBLOCA analysis, implemented beginning with the Cycle 18 operation. This SBLOCA analysis was evaluated with the mixed core of Mark-B12 and Mark*B*HTP and a new PCT of 1444°F was calculated for the limiting Mark-B-HTP fuel type, which bounds the Mark-B12 fuel type. This analysis also includes consideration of the effect of reduced EFW wetting associated with the Enhanced Once-Through Steam Generators (EOTSGs).
2.
Current LOCA Model Assessment The axial power shape assumed by AREVA in their small break LOCA (SBLOCA) analysis in support of TMI, Unit 1 was determined to be not bounding from middle-of-cycle to end-of-cycle (MOC to EOG) conditions. As a result, AREVA developed a bounding axial power shape which conservatively meets all requirements, and this bounding axial power shape resulted in an increase in the reported SBLOCA PCT. The PCT is estimated to increase by 225°F from that previously reported in Note 1 above, resulting in a PCT of 1669°F for the limiting fuel type. The large break LOCA is not affected by this axial power shape issue.