ML20003A379
| ML20003A379 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/28/1981 |
| From: | Delgeorge L COMMONWEALTH EDISON CO. |
| To: | Youngblood B Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8102030582 | |
| Download: ML20003A379 (2) | |
Text
~
- ~
Commonwealth Edison one First National Pfaza. Chicago Utinois
' Address Reply to: Post Office Box 767
. Chicago, Ilknois 60690 January 28, 1981 Mr. B. J.
Youngblood, Chief Licensing Branch No. 1 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 Piping Vibration Monitoring NRC Do cket Nos. 50-373/374
Dear Mr. Youngblood:
In recent discussions with members of your staf f, Commonwealth Edison has requested deferral of a portion of the piping vibration test disepssed in Chapter 14 af the FSAR until such time as all seismic and otner related dynamic supports have been installed.
Spe ci fi cally, it is requested tnat the subject vibration tasting of piping systems be postponed from the preoperational to start-up testing phase, with the understanding that startup would not continue past fuel loading until this testing has been completed.
The technical basis for this postponement is justified in the discussion which follows.
The final piping analysis and support design to reflect the Design Basis Summary Loaos and the "for record" configuration for LaSalle County Station are currently in progress.
Since some changes to the piping support systems are expected to result from these analyses and since many of the pipe supports for the SRV/LOCA dynamic loads have not yet been installed, the vibration preoperational testing programs outlined in preoperational test procedure PT-Si 102 can not now be performed.
Although these dynamic supports do not usually bear the weight of the piping, they do influence the frequency of the system; and, therefore, could cnange drastically the systems response to vibrational loads.
- Thus, in order to evaluate a system for vibration response the dynamic pipe supports must be in place.
However, critical path considerations dictate that the preoperational system test to validate system performance be performeo.
Therefore, it is necessary to request NRC acceptance of performing the vibration tests just prior to or during fuel loading.
All pipe supports will be installed at the time this test is performed; therefore, the vibration monitoring test will more i
v sa s
,. accurately reflect the operating conditions of the system to be tested.
The systems are HPCS, LPCS, RHR, CSCS-ECWS and Standby Liquid Control.
The reactor recirculation system listed in PT-SI-102 was tested fer vibration as part of its preoperational test.
The preceding discussion establishes the need for performing these vibration tests after the system performance tests have been completed.
The following discussion justifies the performance of these tests af ter the preoperational test.
The first consideration that should be noted is that all weight supports are in place when the system perfr rmance preoperational tests are done.
Thus, the piping is adequately Lupported for the weight and thermal loads that result from the test.
Only the supports for the dynamic loads (seismic, SRV and LOCA-related hydrodynamic loads) are not yet installed.
Therefore, the normal preoperational testing in no way jeopardizes the integrity or function of the system.
Secondly, during the performance tests, the piping systems and equipment are visually examined for excessive vibration.
If excessive vibrations occur, the test is discontinued until the problem can-be corrected.
This visual inspection for excessive vibratien is included as part of the system preoperational test procedure and ensures that no vibration damage to the piping or equipment can occur during the performance of the functional test.
In addition, it should be noted that the adverse ef fects of ex ce isive vibration are usually manifested on a long-term basis.
The cyclic nature of vibrational loads indicates that they primarily af fect the fatigue life of the piping.
A large number of stress cy cles must be accumulated by the piping before a f atigue failure can be expected to occur.
This is especially true for low stress levels.
The fact that the piping is visually examined for ex cessive vibration during the performance tests verifies that only low level vibrational stresses are likely to exist during the test.
Be cause toe preoperational system performance tests do not represent an extended operating period, their effects on fatigue life are minimal.
For these reasons, we request NRC acceptance of the postponement of the vibration testing of' piping systems from the preoperational to start-up testing phase, with the understanding that startup would not continue'past fuel load until this test is completed.
The justification herein provided should establish an adequate basis for acceptance of this request.
Very truly,yours, Y
f L. O. DelGeorge Nuclear Licensing Administrator cc:
NRC Resident Inspector - LSCS Ol35A