B11743, Provides Pvrc Damping Curve Info to Clarify Proposed Changes to Criteria Document for safety-related Piping Analyses Under SEP Topic III-6, Seismic Design Considerations

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Provides Pvrc Damping Curve Info to Clarify Proposed Changes to Criteria Document for safety-related Piping Analyses Under SEP Topic III-6, Seismic Design Considerations
ML20138E749
Person / Time
Site: Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date: 10/16/1985
From: Opeka J, Sears C
CONNECTICUT YANKEE ATOMIC POWER CO.
To: Charemagne Grimes
Office of Nuclear Reactor Regulation
References
TASK-03-06, TASK-3-6, TASK-RR B11743, NUDOCS 8510250101
Download: ML20138E749 (2)


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CONNECTICUT YANKEE ATOMIC POWER COMPANY B E R L I N. CONNECTICUT P o B Ox 270 HARTFORD. CONNECTICUT 06141-0270 TELEPHONE 203-665-5000 October 16,1985 Docket No. 50-213 B11743 Director of Nuclear Reactor Regulation Attn: Mr. C. I. Grimes, Chief Systematic Evaluation Program Branch U. S. Nuclear Regulatory Commission Washington, D. C. 20555

References:

1. J. F. Opeka letter to J. A. Zwolinski, dated June 27,1985.

Gentlemen:

Haddam Neck Plant SEP Topic III-6, Seismic Design Considerations In Reference (1), Connecticut Yankee Atomic Power Company (CYAPCO) identified changes to the Criteria Document being used for the analyses of safety related piping under SEP Topic III-6, Seismic Design Considerations.

These changes are intended to incorporate ASME Code Cases N-397 and N-411 and the Independent Support Motion (ISM) response spectra analysis technique.

During a conference call between CYAPCO and the NRC on September 10,1985, the Staff expressed concerns regarding several areas where the combined effect of these changes could result in non-conservative results, and requested that CYAPCO clarify its intent with regard to the proposed changes. Accordingly, the following information is provided:

1. The Pressure Vessels Research Committee (PVRC) damping curve (Code Case N-411) will be used only for piping systems analyzed using the response spectra method. The Code Case damping values will not be used for piping systems analyzed by time-history analysis methods.
2. The PVRC damping curve will be used in its entirety in a given analysis.

Any combination of the PVRC damping values with those suggested by Regulatory Guide 1.61 will not be utilized.

3. The PVRC damping curve will not be used for piping systems analyzed using the Independent Sunm ' Motion response spectra method of analysis.

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t i We trust the above information will be sufficient to resolve any concerns l

regarding the criteria changes proposed by Reference (1). If you have any i additional questions or comments, please contact us.

Very truly yours, i CONNECTICUT YANKEE ATOMIC POWER COMPANY  !

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3. F. Opeka '

Senior Vice President 1

By: C. F. Sears Vlec President t

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