ML19340E650
| ML19340E650 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 12/18/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8101150230 | |
| Download: ML19340E650 (2) | |
Text
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'o UNITED STATES
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NUCLEAR REGULATORY COMMISSION g
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799 ROOSEVELT ROAD b
o GLEN ELLYN, ILLINOIS 60137 December 18, 1980 Gentlemen:
The enclosed IE Supplement No. 4 to Bulletin No. 80-17 is forwarded to you for information. No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely, O...... _ '.s
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,)' James G Keppler Director
Enclosure:
IE Supplement No. 4 to Bulletin No. 80-17
'910115 0WQ
Docket No. 50-373 Docket No. 50-374 Commonwealth Edison Company ATTN:
Mr. Cordell Reed Vice President Post Office Box 767 Chicago, IL 60690 cc w/ encl:
J. S. Able, Director of Nuclear Licensing L. J. Burke, Site Construction Superintendent T. E. Quaka, Quality Assurance Supervisor R. II. llolyoak, Station Superintendent B. B. Stephenson, Project Manager Central Files AD/ Licensing AD/ Operating Reactors AEOD Resident Inspector, RIII PDR Local PDR NSIC
/C Dean Hansell, Office of Assistant Attorney General
\\t SSINS No.:
6820 Accessian No.:
8006190074 UNITED STATES IES 80-17 Sup. 4 NUCLEAR REGUt>. TORY COPMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 18, 1980 IE Supplement 4 to Bulletin No. 80-17:
FAILURE OF CONTROL R005 TO INSERT DURING A SCRAM AT A BWR I
NRC staff evaluation of failures of the continuous monitoring system (CNS) l for the scram discharge volume (SDV) at an operating BWR has identified the need for licensee actions in addition to those requested by IEB 80-17 and r;
Sgpiements 1-3.- The purpose of these actions is to provide assurance that the CMS has been tested to demonstrate operability as installed, remains operable during plant operation, and is periodically surveillance tested to demonstrate continued operability.
f The occurrence of CMS failures at Dresden Nuclear Power Station was discussed in L
IE Information Notice 80-43, which was issued on December 5, 1980 to those operating 8WR's with CMS recently installed.
Subsequently, investigation into the cause of the failure to receive the alarm with the SDV essentially full revealed several items which required correction, including:
1.
Excess portions of transducer cabic were placed in physical positions which would increase external noise sensitivity.
2.
The UT transducers were not placed in a physical position to optimize system sensitivity.
b 3.
A certain amount of " cross-talk" was occuring between redundant trans-ducers located a few feet apart on the same run of 4" pipe.
Station and vendor personnel shortened and rerouted transducer cables to improve noise rejection.
Vendor specialists opticized transducer placement and synchronized both transducers to the same ultrasonic instrument internal clock to minimize cross-talk and improve signal to noise characteristics.
Following these actions the CMS appeared to function properly.
Further difficulties were encountered when apparently minor quantities of water leaked into the SDV as a result of control rod drive scram valve maintenance activities and minor scram outlet valve leakage.
It appears that the trans-ducers are located on a section of SOV piping which forms a local low point.
Accordingly, small amounts of water can accumulate to a depth which triggers the high level alarm (at 1-1/4") before the water drains to the instrument volume. The licensee in conjunction with the MSSS vendor, performed a unit specific analysis for a conservative t* *
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point to 2-1/2".
The system now appe alarm time del y was also installed n.:
DUPLICATE DOCUMENT d
Entire document previously entered into system under:
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No. of a es:
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