ML20039F628
| ML20039F628 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 01/07/1982 |
| From: | Sargent C COMMONWEALTH EDISON CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8201130165 | |
| Download: ML20039F628 (2) | |
Text
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'N Commonwealth Edison
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j one First Nati1nal Plaza. Chicago. Ittinois i
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'J _ Address Reply to: Post Offico Box 767
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/ Chicago, Illinois 60690 en January 7, 1982 C
nECEWED Mr. A. Schwencer, Chief b
JAN 1'21982** 3?
Licensing Branch #2 g uJu usunn emansi Division o f Licensing g
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S. Nuclear Regulatory Commission Washington, DC 20555 gf
Subject:
LaSalle County Station Units 1 and 2 Reactor Water Cleanup System Isolation Time Delay - Technical Specification Proposed Change NRC-Docket-Nos. 50-373-and 50-374-
Dear Mr. Schwencer:
The purpose of this letter is to provide the necessary information to resolve the final open issue on the LaSalle County Station Technical Specification.
Currently, the Technical Specification identifies the Reactor Water Cleanup System Isolation response time (T.S. Table 3.3.2-3 Item 3.a) with a footnote which is in parenthesis.
The NRR Staf f has requested additional clarification of this time delay's function and its impact on analyzed radiological consequences.
The Reactor Water Cleanup System (RWCU) has a built-in time delay of 45 seconds on the delta flow high isolation trip.
This 45 second delay prevents spurious isolation of the RWCU System f rom sensed flow variations due to power process variables that are changes by operator action or otherwise.
The selection of a 45 second time constant was based on operational experience and analysis that shows it is acceptable to the other systems.
The radiological consequences of this time delay assuming a pipe break can be shown to be within the bounds of the analysis of a large steamline pipe break outside the pri; nary containment (FSAR 15.6.4).
Additionally, there are other independent isolation signals such as low reactor level which are designed to actuate isolation signals to the RWCU System in the event of a loss of inventory.
If it is assumed the only isolation signal for the RWCU is the high delta-flow signal with the 45 second time delay, the amount of coolant released is considerably less than that released in the steamline break analysis (approximately 1/30 the quantity with the most pessimistic assumptians).
Thus, the o ffsite dose values for a cleanup line break would be proportionately less than those current-ly identified in the FSAR for the main steam line Dreak outsioe containment.
OI 8201130165 B20i07 PDR ADOCK 05000373 g, O A
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A. Schwencer January 7, 1982 It is, therefore, judged that the 45 second time delay presents no new radiological concern and the footnote in the Technical Specif1caton identifying the time delay can be removed from parenthesis.
If there are any further questions in this regard, please contact this office.
Very truly y ours, bb C. E. Sargent Nuclear Licensing Administrator cc:
NRC Resident Inspector - LSCS 1m 3184N
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