ML19340E655
| ML19340E655 | |
| Person / Time | |
|---|---|
| Site: | Zimmer |
| Issue date: | 12/18/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Borgmann E CINCINNATI GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8101150263 | |
| Download: ML19340E655 (2) | |
Text
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t-UNITED STATES F
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NUCLEAR REGULAiORY COMMISSION n
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REGION lil e
799 ROOSEVELT ROAD o
CLEN 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,
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,/ James G. Keppler Director
Enclosure:
IE Supplement No. 4 to Bulletin No. 80-17
-W C10115 03b39
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-4 Docket No. 50-358
" Cincinnati. Gas and Electric Company ATTN: - Mr. Earl'A. Borgmann Senior Vice President Engineering Services and' Electric Production 139 East 4th Street Cincinnati,'0H' 45201 cc w/ encl:
J. R. Schott, Plant Superintendent
, Central Files AD/ Licensing AD/ Operating Reactors AEOD Resident Inspector, RIII PDR Local PDR N)1C MIC Ifarold W. Kohn, Power.
Siting Commission Citizens Against a -Radioactive
' Environment Helen W. Evans, State of Ohio k
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SSINS No.:
6820 Accessien No.:
8006190074 UNITED STATES IEB 80-17 Sup. 4 i
NUCLEAR REGULATORY COPWISSION i
0FFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 18, 1980 l
l IE Supplement 4 to Bulle' tin No. 80-17:
FAILURE OF CONTROL RODS TO INSERT DURING A SCRAM AT A BWR NRC staff evaluation of failures of the continuous monitoring system (CMS) for the scram discharge volume (SDV) at an operating BWR has identifie,d the 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 demonstrate continued operability.
The occurrence of CMS failures at Dresden Nuclear Power Station was discussed in IE Information Notice 80-43, which was issued on December 5; 1980 to those operating BWR'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 requirvi correction, including:
1.
Excess portions of transducer cable 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.
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 oersonnel shortened and rerouted transducer cables to improve i
noise rejection.
Vendor specialists optimized transducer placement and l
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 cutlet valve leakage.
It appears that the trans-ducers are located on a see.fon of SDV piping which forms a local low point.
Accordingly, small amounts af 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 NSSS vendor, performed a unit l
specific analysis for a conservative t* *
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point to 2-1/2".
The system now appe alarm time delay was also installed DUPLICATE DOCUMENT l
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Entire document previously centered into system under:
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