ML20030B579
| ML20030B579 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 08/10/1981 |
| From: | Delgeorge L COMMONWEALTH EDISON CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| 2403N, NUDOCS 8108180315 | |
| Download: ML20030B579 (3) | |
Text
'O Commonwealth Edison 5
) One First National Plaza. Chicago, Illinois
--n J.3 h Address Reply t;: Post Office Box 767 v/ Chicago, Illinois 60690 x
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g'I August 10, 1981
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I.UU 171981 m> ;2 Mr. A. Scl. encer, Chief h ""co$sYs Licensing Branch 2
\\ h, Division of Licensing U.S. Nuclear Regulatory Commission A
us Washington, DC 20555
Subject:
LaSalle County Station Units 1 and 2 Containment Leak Chase Channels NRC Docket Nos. 50-373/374
Dear Mr. Schwencer:
It has ccme to our atcention that the Nuclear Rea.
Regulation (NRR) Staff has as yet not resolved a question i mised by IE Region III concerning containment leak chase channels at LaSalle County Station.
This question was documented as Unreso'ved Item 373/78-33-17.
As can be seen the question was first raised in 1978 and a f ormal position was pr ovided by Commonwealth Edison, after numerous discussions, in September, 1980.
It is our understanding from the Region III inspector that he concurs with the applicant's position but is awaiting concurrence from NRR.
It is requested that this matter be handled as quickly as possible with the Containment Systems Branch so as not to delay the LaSalle County Unit 1 startup.
The Commcnwealth Edison positior is provided in the encisoure.
If there are any questions in this regard, please direct them to this office.
Very truly yours, AsN L. O. DelGeorge Director of Nuclear Licensing Enclosure cc:
NRC Resident Inspector - LSCS
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2403N 8108180315 810810 PDR ADOCK 05000373 A
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Enclosure Containment Leak Chase Channels LaSalle County Units 1 & 2 Commonwealth Edison was asked to respond to the concern by Mr. F. Maura, the NRC Region III reviewer on preop testing, that the primary containment welds are not subjected to the Leak Rate Test'if the leak channel plugs remain in place and that the leak test channels may not withstand the pool iynamic loads.
Regulatory Guide 1.68, Paragraph C3 states "To the extent practical, the plant conditions during the tests should simulate the actual operating and emergency conditions to which the structure, system, or component may be subjected."
Since plugs are to be in place under operating conditions, the test should be conducted likewise in order to comply with the regulatory guide.
The objective to the Containment Leak Rate Test is to test the entire containment system for leakage and not the primary containment weld in particular.
The containment structure consists of the liner leak test channels, prestressea concrete walls, penetrations, steel dome, etc.
Each component has been tested previously in accordance with the guidalines of Regulatory Guide 1.68.
The leak test channels and the liner weld underneath have been tested at 45 psig during construction, by partial radiography and ultrasonic methods, 100% liquid penetrant, or magnetic particle followed by 100% vacuum box test, and the leak tightness was established at that time.
Venting the leak test channels during the ILRT will not provide information on the leak tightness of the liner weld, because the liner is backed by concrete and is an integral part of the containment wall which will act as a leak tight membrane.
The most effective procedure for performing the test on the liner weld is to test wnan it is not backed by concrete, and this has been done during liner construction.
It is the industry's practice to perform the ILRT'with the plugs in place.
This was dor.c at Beaver Valley Station and Surrey Unii ?.
This is more in line..;th the objective of the test which is to provide the necessary assurance that the facility (liner, leak chase, containment wall, penetrations, dome, etc.) can be operated in a manner that will noc endanger the health and safety of the public.
1 As for the leak channals capability to withstand the pool dynamic loads, the 3/16" continuous fillet weld between the channel and the liner has been assessed for the foll) wing loads:
(a)
SRV Drag Load
, (b)
Condensation Oscillation Drag Load (c)
Chugging Drag Load (d)
Pool Swell Impact Load (e)
Pool Fall Back Impact Load (f)
Accident Temperature These loads were combined using the appropriate load combinations from Table 4.3-2 of the LSCS-Mark II DAR, revision 7
- January, 1980.
The results indicate that the weld has a margin greater than 2.0 under the most critical load combination.
Therefore, the channels can withstand the pool hydrodynamic loads.
Our recommendation remains that the leak channels remain in place, and that the plugs which were originally installed fcr test purposes remain in place during the intitial and subsequent leak rate test.
2403N
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