ML20214P657
| ML20214P657 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 09/15/1986 |
| From: | Sieber J DUQUESNE LIGHT CO. |
| To: | Tam P Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8609240007 | |
| Download: ML20214P657 (2) | |
Text
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'Af Telephone (412) 3934000 Nucfear Group P.O. Box 4 Shippingport, PA 15077-0004 September 15, 1986 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Attn: Mr. Peter S. Tam, Project Manager Project Directorate No. 2 Division of PWR Licensing - A Washington, DC 20555
- Mail Stop 340 -
Reference:
Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Proposed Changes to Damping Values for Seismic Piping Analysis Gentlemen:
As stated in UFSAR, Appendix B, Section B.2.1.2, the present damping values used at Beaver Valley Power Station Unit No.
I for seismically designed piping and components are 0.5 percent for the operating-basis earthquake (0BE) and 1.0 percent for the design-basis earthquake (DBE).
NUREG 1061, " Report to the USNRC Piping Review Committee" has shown that the use of such low damping values for seismic piping analysis are overly conservative, and recommended the damping values given in ASME Code Case N-411.
The values are: five percent below a frequency of 10 Hz; linear reduction from five percent to two percent between 10 Hz and 20 Hz; and two percent above 20 Hz. These damping values would apply for both OBE and DBE cases.
In addition, Regulatory Guide 1.84, Revision 24 has conditionally approved the damping values in Code Case N-411.
Therefore, Beaver Valley, Unit No. I requests to utilize the damping values in Code Case N-411 subject to the following conditions:,
1.
The alternate damping criteria of this Code Case will be used for seismic analysis in cases where new piping is added, existing systems are modified, existing systems are re-evaluated for new requirements and where existing numbers of snubbers are to be reduced provided that the response mode frequencies are limited to 33 Hz and below.
2.
When these alternate damping values are used, they will be used in a given analysis completely and consistently in which current seismic spectra and procedures are employed.
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Beaver Valley Power Station, Unit No. 1 Docket No. 50-334, License No. DPR-66 Proposed Changes to Damping Values for Seismic Piping Analysis Page 2 3.
The damping values will be used in seismic analysis using response spectrum methods and not for seismic analysis using time-history analysis methods.
4.
When used for reconciliation work or for support optimization of existing designs, the effects of increased motion on existing clearances and on line mounted equipment will be reviewed.
5.
The alternate damping values will not be used in seismic analyses of piping systems using supports designed to dissipate energy by yielding or piping in which stress corrosion cracking has occurred.
6.
When these alternate d.unping values are used, the 115 percent peak broadening criteria of Regulatory Guide 1.122, " Development of Floor Design Response Spectra for Seismic Design of Floor-Supported Equipment or Components" will be used.
Attached is check in the amount of $150.00 for payment of the application fee in accordance with 10 CFR 170.
If you have any questions concerning this matter, please contact my office.
Very truly yours, L-
. D. Sieber Vice President Nuclear Operations Attachment cc: Mr. W. M. Troskoski, Resident Inspector U. S. Nuclear Regulatory Commission Beaver Valley Power Station Shippingport, PA 15077 U. S. Nuclear Regulatory Commission c/o Document Branch Washington, DC 20555 Director, Safety Evaluation & Control Virginia Electric & Power Company P. O. Box 26666 One James River Plaza Richmond, VA 23261