ML20154R586
| ML20154R586 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 03/21/1986 |
| From: | Farrar D COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 1459K, NUDOCS 8603310092 | |
| Download: ML20154R586 (2) | |
Text
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Commonwealth Edison
,) One First National Plaza, Chicago. Ilknois C
G 7 Address Reply to. Post Office Box 767 s
\\.j Chicago, Illinois 60690 March 21, 1986 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 Piping Design Criteria NRC Docket Nos. 50-373 and 50-374
Dear Mr. Denton:
This letter supplements our letter of February 11, 1986, on the above subject and is based on telephone conversations held on March 18, 3.986, with Dr. A. Bournia and others of your staff on the above subject.
It is Commonwealth Edison Company's (CECO's) intention to initially use Code Case N-411 damping values for resolution of problems from the ongoing snubber inspection program at LaSalle Station.
In this context, it would be used to eliminate snubbers that currently have experienced degradation due to the environmental and operating conditions they are subject to, or to justify replacing those snubbers with other restraining devices such as rigid restraints. A long term goal, as expr{ssed in our original letter, would still be to perform a snubber reduction program to minimize future concerns of a similar nature. As discussed in the confer-ence call, it has been our practice in the past, and will be followed for all future snubber reduction efforts, to model piping systems for analysis purposes from anchor to anchor. Major pieces of equipment such as the RPV, heaters, etc. are considered anchors for purposes of piping analysis.
Small piping that branches from large headers are modeled individually with an analytical anchor of the branch / header connection. For example, the 4" reactor water cleanup piping subsystem RR-01 is modeled separately from the reactor recirculation system with an anchor modeled at the 24" RHR
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connection. As such, the piping model for which code Case N-411 damping would be used would start at an equipment. nozzle or a large header where smaller piping branches, including all.in-line components such as valves, and terminate at the next equipment nozzle, large header, or structural anchor.
8603310092 86 373
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H. R. Denton March 21, 1986 l
As discussed with your staff, the only major component that is modeled with the piping on the LaSalle project is the recirculation pump.
CECO agrees to review any analysis using PVRC damping on this system (recirculation piping and attached RHR piping) with the NRC/NRR Staff prior to using these results for snubber reduction purposes.
CECO believes the above modeling practices are consistent with existing FSAR' commitments, and as such will require no revision or modification to any licensing documentation. All other commitments as outlined in our February ll,1986, letter on the above subject will be maintained.
For the reasons discussed in the February 11, 1986, letter and its attachments, we would appreciate your expeditious response on this matter.
If further information is needed by your staff, please contact this office.
Sincerely,
_a c
Dennis L. Farrar Director of Nuclear Licensing im cc: Region III Inspector - LSCS Dr. A. Bournia - NRR 1459K