ML20136H209
| ML20136H209 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/03/1986 |
| From: | Allen C COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 1040K, NUDOCS 8601090308 | |
| Download: ML20136H209 (3) | |
Text
s
/C \\ Commonwealth Edison
/ One First National Plaza, Chicago. Illinois I O M Address ficp:y to: Post Othcs Box 767
,,/ Chicago. Illinois 60690 January 3, 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 Proposed Amendments to Technical Specification for Facility Operating License NPF-11 and NPF-18 Low and Degraded Grid Voltage Modification - Supplemental Information NRC Docket Nos. 50-373 and 50-374 Reference (a):
H. L. Massin letter to H. R. Denton dated November 13, 1985.
Dear Mr. Denton:
This letter transmits supplemental information regarding the low and degraded voltage technical specification change request (Reference (a)). This information responds to our telecon of December 18, 1985 and covers the additional information discussed at that time to satisfy concerns of the NRR Staff reviewing the referenced change.
Action 39, as proposed, was written to provide appropriate actions for all potential failures which may occur in the degraded voltage logic.
Different failures require varying levels of remedial actions as discussed below. The actions of the proposed amendment are consistent with the level of degradation of the electrical power system.
It is important to provide technical specifications which provide actions for a range of postulated conditions to avoid misinterpretations or unnecessary actions.
For degraded undervoltage instrumenta identified as Items A and B on Attachment A, if only one instrument is inoperable Action 39 allows the instrument to be placed in the tripped condition (closed contact) within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. This allows the circuit to remain operable in that it will still sense a degraded voltage condition and provide appropriate automatic actions. This condition may remain until the instrument is restored to operable status.
For the portion of the degraded voltage circuit identified as Item C on Attachment A, if any part of this logic circuit is inoperable the degraded voltage automatic actions will not occur. However, the normal (loss of voltage) circuit remains fully operable for any condition where complete loss of voltage occurs. The diesel will perform as required, load shedding will occur, etc. Therefore, the diesel remains operable and need not be declared inoperable immediately.
II 8601090308 860103
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PDR ADOCK 05000373 P
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H. R. Denton January 3, 1986 4
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If any of the remaining circuit is inoperable, the diesel generator is effected and should be declared inoperable (Action 37).
Therefore Action 39 was written to allow a period of 7 days to repair the degraded voltage logic circuit elements if:
(1) The capability
+
of detecting a degraded voltage condition was still available to protect the other two ESF divisions and to alert the control room operator (Requirement i
to " verify that the remaining divisions degraded voltage instruments are i
operable") and (2) if the normal undervoltage circuit was operable (Action 37).
Since the likelihood of a degraded voltage condition is much less than a no-voltage (loss of power) condition, the safety impact of having no
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automatic degraded voltage protection on one ESF division much less than the impact of having the loss of power protection inoperable (Action 37) and is therefore minimal.
Please direct any questions you may have concerning this matter to this office.
One signed original and fifteen (15) copics of this transmittal and its attachment are provided for your use.
Very truly yours, C. M. Allen Nuclear Licensing Administrator im Attachment A cc: Region III Inspector - LSCS A. Bournia - NRR 4
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