ML20151L662
| ML20151L662 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 06/27/1997 |
| From: | Reda R GENERAL ELECTRIC CO. |
| To: | Lyons J NRC (Affiliation Not Assigned), NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20151L120 | List: |
| References | |
| MFN-029-97, MFN-29-97, RJR-97-084, RJR-97-84, NUDOCS 9708070136 | |
| Download: ML20151L662 (2) | |
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GENuclearEnergy seam.cerc,,
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June 27,1997 RJR-97-084
' MFN-029-97 Document Control Desk US Nuclear Regulatory Commission l
Washington,DC 20555-0001 I
t Attention: J. E. Lyons, Chief Reactor Systems Branch I
Subject:
' Repwti g of Changes and Errow in ECCS Evaluation Models e
Reference:
Letter, R.J. Reda to the Document Control Desk (R. C. Jones,Jr.), Referring
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of Changes and Enors in ECCSNJ"-. Modds, datedJune 28,1996 (MFN-088-96).
The purpose of this letter is to assist licensees with reponing, in accordance with l
10CFR50.46 (a) (5) (ii), the impact of changes and errors in the methodology used by GE to demonstrate compliance with the Emergency Core Cooling System (ECCS) requirements of j
10 CFR 50.46. This report covers the period from the last report (Reference) to the present.
It is noted that Peak Cladding Temperature (PCT) variations resulting from plant speciSc system or fuel changes are not addressed in this letter. These should be treated, as
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appropriate, on a plant specific basis in acconiance with other sections of 10CFR50.
There have.been no changes or errors identified for the SAFE /REFLOOD model described in NEDE 20566-P-A, Analytu;olMaddforLass-of-Coolant Analysis in Accordance witA 10 CFR 50AppendixK There have been no changes or errors identified for the SAFER /GESTR model described in NEDE 23785-1-P-A, tac CESTR-LOCA and SAFER ModelsforEvoluatson ofLoss-of-Coolant Acculents, and NEDE SO996-P-A, SAFER Modelfor Evaluation of Loss-of-Calant AccidentsforJd Pump and Non-]d Pump Plants.
During the reporting period an input error was discovered in~ the GEGAP gap conductance model which impacts ECCS/LOCA MAPLHGR margins in SAFE /REFLOOD plants using Gell or GEIS fuel. The nature of the input error in the GEGAP analysis was the use of a mean value of fuel pellet densi6 cation when a 95% confidence value should have been used. The expectation of the potenti4 consequence of this type of error is a higher gap conductance between the fuel pellet and the cladding. This higher gap conductance would 9700070136 970728 PDR ADOCK 05000333 P
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Document Control Desk j
U. S. Nuclear Regulatory Commission
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e result in a lower initial stored energy in the fuel pellet at the onset of the LOCA and, thus, t
result in the calculation of a lower PCT during the LOCA. An analysis showed that the new corrected inputs from GEGAP resulted in an increase in the calculated PCT of as much as 15'F.
In the mid-1980s, prior to the reponing requirements of 10CFR50.46, GE increased the manufactured fuel density for all fuels. 'Ihis increased fuel density was a recognized conservatism in the ECCS analysis, therefore no effort was made to redo all of the plant analysis, but rather to hold it as a known conservatism in the analysis. This conservatism, were it to be implemented in an ECCS analysis would result in a calculated PCT decrease of 25*F and could be used to offset the PCT increase due to the GEGAP error.
This conservatism, which was the use of a lower than actual fuel pellet density in the core heatup calculation, affects both the SAFE /REFLOOD and the SAFER /GESTR models. Most licensees have determined that they do not need to incorporate this known conservatism in
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their current ECCS analysis.
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e All utilities using these evaluation models have been noti 5ed of these changes.
If you have any questions, please call me crj. L Embley at (910) 675-5774.
Sincerely,
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a R.J. Reda,' Manager Fuels and Facility Licensing (910) 675-5608 cc:
C.J. Monetta J. L Embley l
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