ML19353A070
| ML19353A070 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 12/18/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| NUDOCS 8101070066 | |
| Download: ML19353A070 (1) | |
Text
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'o UNITED STATES m
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NUCLEAR REGULATORY COMMISSION l
REGION 1
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,5 631 PARK AVENUE U
g KING oF F AUSSIA, PENNSYLVANIA 19406 J
DEC 181980 7
Docket No. 50-245 Northeast Nuclear Energy Company ATTN: fir. W. G. Counsil
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~5 Senior Vice President - Nuclear
.M Engineering and Operations c,
a P. O. Box 270 Hartford, Connecticut 06101 Gentlemen:
The enclosed Supplement No. 4 to IE Bulletin No. 80-17, " Failure of Control Roos to Insert During a Scram at a BWR" is forwarded to you for action.
A written response is required.
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 following identification of problems through the Bulletin.
If you desire additional information regarding this matter, please contact this office.
Sincerely, 171/% Na h? Is Bn ce H. Grier l
irector
Enclosures:
l 1.
Supplement No. 4 to IE Bulletin No. 80-17 2.
List of Recently Isseed IE Bulletins CONTACT:
D. L. Caphton (215-337-5266) l l
l cc w/encls:
J. F. Opeka, System Superintendent Nuclear Operations E. J. Mroczka, Station Superintendent D. G. Diedrick, Manager of Quality Assurance l
J. R. Hinnelwright, Licensing Safeguards Engineer i
i
SSiNS No.:
6820 Accession No.:
8006190074 UNITED STATES IEB 80-17 Sup. 4 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 18, 1980 IE Supplement 4 to Colletin 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 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 operatior., 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 required 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 positicn 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.
1 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 activities and minor scram outlet valve leakage.
It appears that the trans-ducers are located on a section of SDV piping which forms a local low point.
Accordingly, small amounts
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a depth which triggers the high level alarm (at t
volume.
The licensee in it specific analysis for a arm point to 2-1/2".
The sys DUPLICATE DOCUMENT alarm time delay was also Entire document previously i
entered into system under:
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