ML19340E652
| ML19340E652 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 12/18/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8101150240 | |
| Download: ML19340E652 (1) | |
Text
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UNITED ST ATES 4
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NUCLEAR REGULATORY COMMISSION
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r llEGION 111 799 ROOSEVELT ROAD g
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,0 GLEN ELLYN, ILLINOIS 60137 December 18, 1980 Gentlemen:
Enclosed is IE Supplement No. 4 to Bulletin No. 80-17 which requires action by you with regard to your power reactor facility (ies) with an operating license.
In order to assist the NRC in evaluating the value/ impact of each Bulletin on licensees, it would be helpful if you would provide an estimate of the manpower expended in conduct of the review and preparation of the report (s) required by the Bulletin.
Please estimate separately the manpower associated with corrective actions necessary following identification of problems through the Bulletin.
Should you have any questions regarding this Bulletin or the actions required by you, please contact this office.
Sincerely,
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,7 James G. KeppIer Director
Enclosure:
IE Supplement No. 4 to Bulletin No. 80-17 8'70115 0 gqo 9
Docket Nos. 50-10, 50-237, 50-249; 50-254, 50-265 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 D.
1 Scott, Station Superintendent N. Kalivianakis, Plant Superintendent Central Files AD/ Licensing AD/ Operating Reactors AEOD Resident Inspectors, RIII PDR Local PDR
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Dean Hansell, Office of Assistant Attorney General
$5 INS No.:
8820 Accessicn No.:
8006190074 UNITED STATES IE8 80-17 Sup. 4 NUCLEAR REGULATORY C0f0GSSION OFFICE OF INSPECTION AND ENFORCEMENT 4
1RSHINGTON, D.C.
20555 December 18, 1980
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-IE Sgpiement 4 to Bulletin No. 80-17:
FAILURE OF CONTROL RODS TO INSERT DURING A SCRAN AT A 8WR p
p NRC staff evaluation of failures of the continuous monitoring system (CMS)
!b for the scram discharge volume (SDV) at an operating BWR has identified the
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need for licensee actions in addition to those requested by IEB 80-17 and Supplements 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 L,
demonstrate continued operability.
4 The occurrence of CMS failures at Dresden Nuclear Power Station was discussed in P
IE Infonnation Notice 80-43, which was issued on December 5,1980 to those W
operating BWR's with CMS recently installed.
Subsequently, investigation into J
the cause of the failure to receive the alarm with the SDV essentially full revealed several items which required correction, including:
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1.
Excess portions of transducer cable were placed in physical positions which would increase external noise sensitivity.
2.
The LfT transducers were not placed in a physical position to optimize
?.g system sensitivity.
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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 optimized 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 4
activities and minor scram outlet valve leakage.
It appears that the trans-4 ducers are located on a section of SDV piping which forms a local low point.
Accordingly, small amounts of water can accumulate to a depth which triggers the high level alare (at 1-1/4") before the water drains to the instrument volume. The licensee in conjunction with the NSSS vendor, performed a unit specific analysis for a conservative point to 2-1/2".
The system now appe alarm time del y was also installed r.
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. DUPLICATE DOCUMENT Entire document previously entered into system under:
xNo 900G t9o eni No. of es:
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