ML19353A290
| ML19353A290 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, LaSalle  |
| Issue date: | 12/17/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8101080060 | |
| Download: ML19353A290 (2) | |
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GLEN ELLYN, ILLINOIS 60137 December 17, 1980 Gentlemen:
The enclosed IE Information Notice No. 80-45 provides early notification of an event that may have safety significance. Accordingly, you should reveiw the Information Notice for possible applicability to your facility.
No specific action or response is requested at this time; however, con-tingent upon the results of further staff evaluation, a Bulletin or a Circular recommending or requesting specific licensee actions may be issued.
If you have any questions regarding this matter, please contact this office.
Sincere 1y, p.l?&
ames G. Keppl i
Director
Enclosure:
IE Information Notice No. 80-45 8103080 0040
Docket Nos. 50-10, 50-237, 50-249; 50-254, 50-265; 50-375, 50-374 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. J. Scott, Station Superintendent N. Kalivianakis, Plant Superintendent L. J. Burke, Site Construction Superintendent T. E. Quaka, Quality Assurance Supervisor R. H. Holyoak, Station Superintendent B. B. Stephenson, Project Manager Central Files AD/ Licensing AD/ Operating Reactors AEOD Resident Inspectors, RITI PDR Loca PDR NS.
iC Dean Hansell, Office of Assistant Attorney General e
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SSINS No.:
6835 Accession No..
801216002 IN 80-45 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 17, 1980 IE Information Notice No. 80-45:
POTENTIAL FAILURE OF BWR BACKUP MANUAL SCRAM CAPABILITY The primary purpose of this Notice is to advise BWR licensees that a mechanism exists which could defeat one of the backup manual scram (reactor trip) features normally available to the reactor operator.
In some GE-designed reactors, placing the Mode Selector Switch (MSS) in " Shutdown" should actuate a scram.
This feature is used at some facilities as part of a normal reactor shutdown, and for certain plant situations the Technical Specifications require placing the MSS in the " Shutdown" position as a means of attaining immediate shutdown.
As described below, a situation may arise that blocks this scram.
The Pilgrim Nuclear Power Station has reported that following the loss of power from a vital M-G set and manual transfer to the alternate power source, the annunciator " Shutdown Scram Reset Permissive" came on and stayed on.
Since such an annunciator may not be provided for all BWRs, some facilities may not be able to detect this condition.
Subsequent investigation revealed that when one RPS bus power supply is lost and the MSS is in the "Run" mode, relay K-17 is immediately deenergized and after two seconds one of two series bypass contacts in the MSS scram circuit is closed.
Upon restoration of RPS bus power, it is possible for relay K-16 to be energized before K-17 (i.e., a relay race).
If this occurs, the following conditions will result: (1) the normally open K-16 contact in the MSS scram bypass circuit is closed, thereby bypassing the MSS in
" Shutdown" Scram; and (2) relay K-17 will be kept deenergized.
Even with this condition (i.e., the bypass circuit made up and the MSS in "Run")
a Scram should occur if the MSS is turned in a deliberate manner to " Shutdown" with a pause in either the "Startup" or " Refuel" mode; however, if the MSS is turned to " Shutdown" quickly such that relay K-17 is not energized, a Scram due to MSS manipulation may not occur.
We understand that General Electric has been informed of this potential for bypassing the MSS and that General Electric is preparing a Service Information Letter (SIL) containing recommendations for preventing such bypassing.
This Information Notice is provided as an early notification of a possibly significant matter that is still under review by the NRC staff.
Recipients should review the information for possible applicability to their facilities.
No specific action or response is requested at this time; however, if NRC evaluations so indicate, further licensee actions may be requested or required.
If you have any question regarding this matter, please contact the director of the appropriate NRC Regional Office.
O 1
IN 80-45 December 17, 1980 i
RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Sub_iect Issue Issued to I
80-44 Actuation of ECCS in the 12/16/80 All PWR facilities Recirculation Mode While with an OL or CP in Hot Shutdown 1
80-43 Failures of the Continuous 12/5/80 All power reactor Water Level Monitor for facilities with OL the Scram Discharge Volume or CP at Dresden Unit No. 2 80-42 Effect of Radiation on 11/24/80 All power reactor Hydraulic Snubber Fluid facilities with OL or CP 80-41 Failure of Swing Check 11/10/80 All power reactor Valve in the Decay Heat facilities with an OL Removal System at Davis-or CP Besse Unit No. 1 80-40 Excessive Nitrogen Supply 11/10/80 All power reactor Pressure Actuates Safety-facilities with y
Relief Valve Operation to OL or CP Cause Reactor Depressur-ization 80-39 Malfunctions of Solenoid 10/31/80 All light water reactor Valves Manufactured By facilities with Valcor Engineering Corporation OLs or cps 80-38 Cracking in Charging Pump 10/30/80 All PWR facilities Casing Cladding with an OL or CP 80-37 Containment Cooler Leaks 10/24/80 All power reactor and Reactor Cavity facilities with Flooding at Indian Point OLs or cps Unit 2 80-36 Failure of Steam 10/10/80 All power reactor Generator Support Bolting facilities with OLs or cps 80-35 Leaking and Dislodged
-10/10/80 All categories G and Iodine-124 Implant Seeds G1 medical licensees OL = Operating Licenses CP = Construction Permits
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