ML20235M416
| ML20235M416 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/29/1987 |
| From: | Michael Ray TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8710060187 | |
| Download: ML20235M416 (3) | |
Text
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e TENNESSEE VALLEY AUTHORITY CHATTANOOGA. TENNESSEE 374o1 SN 157B Lookout Place
,8EP 201987 U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlemen:
In the Matter of
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Docket Nos. 50-327 Tennessee Valley Authority
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50-328 l
SEQUOYAH NUCLEAR PLANT (SQN) - USE OF-AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME) CODE CASE N-411 j
References:
1.
Letter from Harol' R. Denton to H. G. Parris dated December 2, 1985, "Use of ASME Code Cases N-397 and N-411 for the Sequoyah Nuclear Plant Units 1 and 2" 2.
TVA Letter to Director of Nuclear Reactor Regulation dated February 12, 1986 In reference 1 NRC conditionally approved the use of ASME Code Case N-411 for SQN subject to IVA's commitment to impose the following two conditions:
" Commit to use the case for piping systems analyzed by response spectrum methods and not those using time-history analysis
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methods."
"When the alternate damping criteria of this code case are used, they will be used in their entirety in a given analysis
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and shall not be a mixture of Regulatory Guide 1.61 criteria and the alternated criteria of this code case."
TVA's commitment to meet these conditions was transmitted to NRC by reference 2.
TVA also documented this in Amendment No. 3 of the Final Safety Analysis Report (FSAR) in table 3.7.1-3.
Code Case N-411 is being applied to the analysis of piping in two structures:
Seismic analysis of piping in the additional diesel generator building (ADGB).
Design Basis Accident (DBA) analysis of piping attached to the steel containment vessel (SCV).
The response spectrum method was used in all analyses.
For the sciemic analysis of the piping, all the conditions stipulated in the NRC letter were met.
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The piping attached to the SCV was anclyzed for the DBA vibratory motion applying response spectra only'to the SCV attachment points using the independent support motion net.tod.
The remainder of the pipe supports (i.e.,
supports not attached to the SCV) have a zero DBA spectra applied to them for this analysis.
The analysis was performed this way becsuse only the supports connected to the SCV experience vibratory motion for the DBA loading condition.
Also, Code Caso N-411 damping has been used for the following cases Where the requisite conditions of reference 1 apply:
Code Case N-All damping has been used to justify not reanalyzing piping in the essential raw cooling water (ERCW) pipe tunnel. When spectra at 1/2-percent and 1-percent damping was generated for the ERCW pipe tunnel, this spectra was larger than the spectra used for analysis.
To justify not reanalyzing the piping, an evaluation was made to show that Code Case N-All damped spectra would be low enough to ensure that the spectra used for the analysis was acceptable.
f CodeCaseN-411 damping lhusbeenusedtorecalculatepipemovementsat support points on ERCW })1 ping in the annulus area.
The incrr.ased damping was used to reduce the~ pApe movements to a level where the gaps in the support would accommodate the pipe movements.
Code Case N-411 damping has been used to analyze portione of the seismic Category 1(L) fire protection system piping.
In summary, SQN has utilized the damping provisions of Code Case N-411 only l
for the cases described above.
Future use of Code case N-411 dumping will j
only be approved if all the conditions outlined by llRC are met.
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Very ttuly yours, t
T'INNESSEE '.'tLLEY ALTHORITY p
M. J. Ray, Depuf.y Director j
Nuclear Licensing and l
Regulatory Affairs
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see page 3 i
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U.S. Nuclear Regulatory Commission l
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cc:
Mr. G. G. Zech, Assistant Director for Inspection Programs Office of Special Projects U.S. Nuclear Regulatory Commission 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. J. A. Zwolinski, Assistant Director
- for Projects Division of TVA Projects Office of Special Projects U.S. Nuclear Regulatory Commission 4350 East-West Highway EWW 322 l
Bethesda, Maryland 20814 Sequoyah Resident Inspector Sequoyah Nuclear Plant 2600 Igou Ferry Road Soddy Daisy, Tennessee 37379 2
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