ML20043G794
| ML20043G794 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 06/12/1990 |
| From: | Sieber J DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9006210140 | |
| Download: ML20043G794 (1) | |
Text
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aver Whey Itwer Station
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June 12, 1990
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S. Nuclear Regulatory Commission Attn:
Document Control Desk-L Washington, DC 20555
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Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Additional Information For Operating License Change No. 156 Gentlemen This letter documents our response to an NRC verbal request via conference call between Duqueane Light Company, Westinghouse-and NRC staff on May 24, 1990 concerning our proposed Operating License Change Request No.
156.
The NRC staff is reviewing WCAP-11419 that we provided as justification for the proposed technical specification change and had requested clarification of the magnitude of the confidence level of the Westinghouse Setpoint Methodology.
Westinghouse provided the requested clarification in the verbal discussion and this clarification.is documented in the following.
The basic' Westinghouse setpoint. methodology is the square root of the sum of. the squares technique-after. accounting for statistically interactive effects.
Westinghouse conservatively assumes several parameters to be dependent, even though it is posrd.ble-with the use of "as left"/"as found" plant data to determine that the calibration, tolerance is an absolute
- value, 1.e.,
the "as left" condition of the module or string is not allowed to exceed the calibration' tolerance.
- Thus, the calibration tolerance confidence level is better than'95%.
i Westinghouse also assumes a conservative allowance magnitude for rack drift and treats environmental allowances in the most conservative
- fashion, i.e.
as biases.
While Westinghouse has been careful to note only that 'the methodology results in a
95%
probability at a high confidence
- level, it is
- believed, based on the conservatism noted above, that the confidence level is 95% or better.
If you have any questions regarding this submittal, please call me or members..of my staff.
Very truly yours, ELSAr ----
D.
Sieber
[ Rice President Nuclear Group cc:
Mr. J.
Beall, Sr.' Resident Inspector O
Mr. T. T. Mcrtir, NRC Region I Administrator 0
]
Mr. A. W.
DeAgazio, Project Manager
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