ML073130152
| ML073130152 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 12/06/2007 |
| From: | Adrian Muniz NRC/NRR/ADRO/DORL/LPLIII-1 |
| To: | Jennifer Davis Detroit Edison |
| muniz A, ADRO/DORL/415-4044 | |
| References | |
| TAC MD3492 | |
| Download: ML073130152 (4) | |
Text
December 6, 2007 Mr. Jack M. Davis Senior Vice President and Chief Nuclear Officer Detroit Edison Company Fermi 2 - 210 NOC 6400 North Dixie Highway Newport, MI 48166
SUBJECT:
FERMI 2 - CHANGES TO ANALYSIS OF RECORD FOR LARGE-BREAK LOSS-OF-COOLANT ACCIDENT (TAC NO. MD3492)
Dear Mr. Davis:
In a letter dated July 3, 2007, Detroit Edison (the licensee) notified the Nuclear Regulatory Commission (NRC), pursuant to Section 50.46, Acceptance criteria for emergency core cooling systems [ECCS] for light-water nuclear power reactors, of Part 50 to Title 10 of the Code of Federal Regulations (10 CRF 50.46), of a significant change in the General Electric plant-specific ECCS evaluation for Fermi Unit 2. Specifically, the licensee identified a change in the evaluation methodology that resulted in an analyzed increase in the peak cladding temperature (PCT) of 55 °F for GE14 fuel.
Section 50.46(a)(3)(i) of 10 CFR Part 50 states that each licensee shall estimate the effect of any change to or error in an acceptable evaluation model or in the application to determine if the error is significant. For this purpose, a significant change or error is one which results in a calculated peak fuel cladding temperature different by more than 50 °F from the temperature calculated for the limiting transient using the last acceptable model, or is a cumulation of changes or errors such that the sum of the absolute magnitudes of the respective temperature changes is greater than 50 °F. Further, section 50.46(a)(3)(ii) states that For each change to or error discovered in an acceptable evaluation model or in the application of such a model that affects the temperature calculation, the applicant or licensee shall report the nature of the change or error and its estimated effect on the limiting ECCS to the Commission at least annually as specified in 50.4. If the change or error is significant, the applicant or licensee shall provide this report within 30 days and include with the report a proposed schedule for reanalysis or taking other action as may be needed to show compliance with 50.46 requirements.
The licensee has reported the estimated effect (55 °F) of the error and that the adjusted estimated PCT is 1675 °F. The NRC staff finds that the licensee has identified and quantified the effect of the reported error as required by 10 CFR 50.46, and has properly concluded that the report was required. In addition, the licensee has proposed a schedule for reanalysis (not to reanalyze at this time) as required by the regulation. Thus, the NRC staff finds that the licensee has complied with the cited reporting criteria of 10 CFR 50.46(a)(3) and concludes that the licensee has properly executed the error evaluation provision of the regulation.
The licensee has proposed not to propose a reanalysis schedule at this time because of a perceived large margin to the 2200 °F fuel performance criterion in 10 CFR 50.46(b)(1). The licensee has stated that it would continue to track future methodology changes and errors in the
J. M. Davis methodology 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 continue to be met. The NRC staff finds the proposal acceptable because the licensee has quantified the effect of the error, and has proposed a reasonable program to continue tracking errors and changes in the loss-of-coolant accident analyses of record results.
The NRC staff also notes that the licensee made its decision to report and not to commit to a reanalysis schedule at this time based on one error with an effect large enough to trip the reporting criterion, and a perceived large margin to the 2200 oF PCT criterion. The staff clarifies that the reporting requirement criterion is based on a sum of absolute values, and keeping the analyses representative of the plant, regardless of the estimated PCT itself. (An estimated PCT greater than 2200 oF would have required more drastic actions.) Using only the margin between estimated PCT and the PCT criterion of 2200 oF as a reanalysis criterion can defeat the purpose of the tracking of errors in that many mutually cancelling errors and changes can render the estimated PCT no longer credibly representative of the plant if margin to 2200°oF PCT is used as the only criterion for reporting. In the current case, this did not happen because there was only one reported error.
In summary, the NRC staff finds the licensees report acceptable because the licensee correctly reported an error that caused significant deviation in the estimated PCT as defined in 10 CFR 50.46(a)(3)(i), and proposed an acceptable course of action in response to the discovered error.
Sincerely,
/RA/
Adrian Muniz, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341 cc: See next page
J. M. Davis methodology 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 continue to be met. The NRC staff finds the proposal acceptable because the licensee has quantified the effect of the error, and has proposed a reasonable program to continue tracking errors and changes in the loss-of-coolant accident analyses of record results.
The NRC staff also notes that the licensee made its decision to report and not to commit to a reanalysis schedule at this time based on one error with an effect large enough to trip the reporting criterion, and a perceived large margin to the 2200 oF PCT criterion. The staff clarifies that the reporting requirement criterion is based on a sum of absolute values, and keeping the analyses representative of the plant, regardless of the estimated PCT itself. (An estimated PCT greater than 2200 oF would have required more drastic actions.) Using only the margin between estimated PCT and the PCT criterion of 2200°oF as a reanalysis criterion can defeat the purpose of the tracking of errors in that many mutually cancelling errors and changes can render the estimated PCT no longer credibly representative of the plant if margin to 2200°oF PCT is used as the only criterion for reporting. In the current case, this did not happen because there was only one reported error.
In summary, the NRC staff finds the licensees report acceptable because the licensee correctly reported an error that caused significant deviation in the estimated PCT as defined in 10 CFR 50.46(a)(3)(i), and proposed an acceptable course of action in response to the discovered error.
Sincerely,
/RA/
Adrian Muniz, Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-341 cc: See next page DISTRIBUTION:
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Fermi 2 cc:
David G. Pettinari Legal Department Mr. Joseph H. Plona 688 WCB Vice President - Nuclear Generation Detroit Edison Company Detroit Edison Company 2000 2nd Avenue Fermi 2 - 210 NOC Detroit, MI 48226-1279 6400 North Dixie Highway Newport, MI 48166 Michigan Department of Environmental Quality Waste and Hazardous Materials Division Radiological Protection and Medical Waste Section Nuclear Facilities Unit Constitution Hall, Lower-Level North 525 West Allegan Street P.O. Box 30241 Lansing, MI 48909-7741 U.S. Nuclear Regulatory Commission Resident Inspector's Office 6450 N Dixie Highway Newport, MI 48166 Mr. M. V. Yudasz, Jr., Director Monroe County Emergency Management Division 965 South Raisinville Road Monroe, MI 48161 Ronald W. Gaston Manager, Nuclear Licensing Detroit Edison Company Fermi 2 - 200 TAC 6400 North Dixie Highway Newport, MI 48166 Supervisor - Electric Operators Michigan Public Service Commission P.O. Box 30221 Lansing, MI 48909 Wayne County Emergency Management Division 10250 Middlebelt Road Detroit, MI 48242 June 22, 2007