ML19340E638
| ML19340E638 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 12/18/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dewitt R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| NUDOCS 8101150204 | |
| Download: ML19340E638 (2) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION 3,,
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%,.....f 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 britten 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 8101150304 Q
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Docket No. 50-155 Consumers Power Company ATTN:
Mr. R. B. DeWitt Vice President Nuclear Operations 212 West Michigan Avenue Jackson, MI 49201 cc w/ enc 1:
D. P. lloffman, Nuclear Licensing Administrator C. J. Ilartman, Plant Superintendent Central Files AD/ Licensing AD/ Operating Reactors AEOD Resident Inspector, RIII PDR Local PDR d IC TIC Ronald Callen, Michigan Public Service Commission
i SSINS No.:
6820 Acesssicn No.:
8006190074 LNIITED STATES IE8 80-17 Sup. 4 NUCLEAR REGULATORY 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 SCRAN AT A BWR NRC staff evaluation of failures of the continuous monitoring system (CMS)
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for the scram discharge volume (SDV) at an operating BWR has identified the i
need for licensee actions in addition to those requested by IEB 80-17 and l.
Supplements 1-3.
The purpose of these actions is to provide assurance that i
the CMS has been tested to demonstrate operability as installed, remains i
operable during plant operation, and is periodically surveillance tested to demonstrate continued operability.
I!
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 i ~
operating BWR's with CMS recently installed.
Subsequently, investigation into the cause of the failure to receive the alarm with the SDV essentially full i
revealed several items which requir6d correction, including:
1:
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1.
Excess portions of transducer cable were placed in physical positions j
which would increase external noise sensitivity.
f 2.
The LTT transducers were not placed in a physical position to optimize p
system sensitivity.
L 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.
s Station and vendor personnel shortened and rerouted transducer cables to improve U
noise rejection.
Vendor specialists optimized transducer placement and synchronized both transducers to the same ultrasonic instrtament internal clock to minimize cross-talk and improve signal to noise characteristics.
Following i
these actions the CMS appeared to function properly.
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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 SDV r. ing 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 Itcensee in conjunction with the NSSS vendor, performed a unit specific analysis.for a conservative
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point to 2-1/2".
The system now appe alarm time del y was also installed
. DUPLICATE DOCUMENT s
Entire document previously entered into system under:
ANO 90%i9o es15 No. of es:
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