ML20138C142

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Informs of Util Program to Optimize Use of Snubbers on Piping Sys & Requests Approval for Use of ASME Code Cases N-411 & N-397.Following NRC Approval,Necessary FSAR Changes Will Be Implemented
ML20138C142
Person / Time
Site: Limerick Constellation icon.png
Issue date: 03/27/1986
From: Kemper J
PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To: Butler W
Office of Nuclear Reactor Regulation
References
CON-#286-679, RTR-NUREG-1061 OL, NUDOCS 8604020369
Download: ML20138C142 (3)


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PHILADELPHIA ELECTRIC COMPANY 23O1 MARKET STREET P.O. BOX 8699 PHILADELPHIA PA.19101 JOHN S. KEMPER VIC E #R ESID E N T sossent a neses ano mass mecn Mr. W. R. Butler, Director Docket No.- 50-353 BWR Project Directorate #4 Division of Licensing U. S. Nuclear Regulatory Commission l Washington, DC 20555

Subject:

Limerick Generating Station Unit 2 Use of Alternate Damping and Spectral Shifting Criteria File: GOVT 1-1 (NRC)

Dear Mr. Butler:

The purpose of this letter is to inform you of Philadelphia Electric Company's (PECo) program to optimize the use of snubbers on the piping systems of Limerick Unit 2 and to request NRC approval for use of the two ASME Code Cases described below. The snubber optimization program is based on application of the dynamic analyses methods that have been developed to more realistically assess the behavior of piping systems undergoing dynamic excitation. Use of these methods is recommended by the NRC Piping Review Committee in NUREG-1061, Volume 5, published in April, 1985.

l Two of the NUREG-1061, Volume 5 recommended analysis methods are contained in ASME Code Case N-411 " Alternative Damping Values for Seismic Analysis of Piping,Section III, Division 1, Class 1, 2 and 3 Construction" and Code Case N-397, " Alternative Rules to the Spectral Broadening Procedures of N-1226.3 for Classes 1, 2, and 3 Piping,Section III, Division 1". Philadelphia Electric Company requests NRC approval to use the criteria and methods in the above code cases, or Regulatory Guide 1.61, where appropriate, as alternatives to methods currently described in the FFAR. The code cases will be used only in response spectra type analyses for seismic and seismic-like building filtered loads, such as hydrodynamic. Code Case N-411 may also be used in response spectra analyses for loads resulting from annulus l pressurization. For frequencies between 33 Hz and 100 Hz, when ASME Code Case N-411 is applied, damping will be limited to 2%. The code

cases will be used on Limerick Unit 2 for new dynamic analyses of piping and pipe mounted equipment, reanalysis for snubber reduction and reconciliation. When the damping criteria of ASME Code Case N-411 8604020369 960327 PDR ADOCM 05000353 Qq i

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are applied, they will be used in their entirety in a given load cane within an analytical problem and will not be mixed with criteria of Regulatory Guide 1.61 or the FSAR. The individual load cases (i.e.

seismic, chugging, condensation oscillation, annnulus pressurization, or SRV discharge) will then be combined in accordance with FSAR Section 3.9.

Whenever ASME Code Case N-411 is used the system predicted maximum displacements will be checked for adequate clearance with adjacent structures, components and equipment, and mounted equipment aill be designed to withstand the increased motion.

Following your approval, necessary FSAR changes will be implemented.

Please contact us if you require additional information.

Sincerely, 4

See Attached Service List RRH/pdO3208603 l

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cc: Troy B. Conner, Jr., Esq.

Ann P. Hodgdon, Esq.

Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Phyllis'Zitzer Charles W. Elliot, Esq.

Barry M. Hartman, Esq.

Mr. Thornas Gerusky Director, Penna. Emergency Management Agency Angus R. Love, Esq.

David Wersan, Esq.

Robert J. Sugarman, Esq.

Kathryn S. Lewis, Esq.

Spence W. Perry, Esq.

Jay M. Gutierrez, Esq.

Atcmic Safety & Licensing Appeal Board-Atcmic Safety & Licensing Board Panel Docket & Service Section Mr. E. M. Kelly Mr. Timothy R. S. Canebell

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