ML20002C248
| ML20002C248 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 12/18/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Crane P PACIFIC GAS & ELECTRIC CO. |
| References | |
| NUDOCS 8101090775 | |
| Download: ML20002C248 (1) | |
Text
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'o UNITED STATES
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g/,j NUCLEAR REGULATORY COMMISSION g.4
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1990 N. CALIFORNIA BOULEVARD
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WALNUT CREEK CALIFORNIA 94596 December 18, 1980 Docket No. 50-133 Pacific Gas and Electric Company P. O. Box 7442 San Francisco, California 94106 Attention: Mr. Philip A. Crane, Jr.
Assistant General Counsel 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.
l Sincerely, l
,~.e db-R. H. Engelken Director
Enclosures:
1.
IE Supplement No. 4 to Bulletin No. 80-17 2.
Recently issued IE Bulletins cc w/ enclosures:
J. D. Shiffer E. Weeks W. A. Raymond
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e SSINS No.: 6820 Accession ?!o. :
8006190074 UNITED STATES IEB 80-17 Sup. 4 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
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December 18, 1980 IE Supplement 4 to Bulletin 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 identified the need for licensee actions ir 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 den.onstrate operability as installed, remains
. operable during plant operatior., and is periodically surveillance tested to demonstrate continued operability.
The occurrence of CMS failures at Oresden Nuclear Power Station was discussed in IE Information Motice 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 tNe alann with the SDV essentially full revealed several items which required :oi rection, including:
1.
Excess portions of transducer cable were placed in physical positions which would increase external noise 3ensitivity.
2.
The UT transducers were not placed in 0 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 samt 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 micor quantities of water leaked into the SDV as a result of control rod drive scrarc valve maintenance activities and minor scram outlet valve leakage.
It appears that the trans-
' local low point.
ducers are located on_
Accordingl th which triggers the high 1, DUPLICATE DOCUMENT the instrument volume. Ti performed a unit specific at Entire document previously d reset the alarm point to 2 entered into system under:
ly.
A five second alarm time rious alarms.
No. of pages:
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