ML19341C047
| ML19341C047 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 12/17/1980 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Polant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 8102280513 | |
| Download: ML19341C047 (1) | |
Text
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UNITED STATES PDR:HQ
[ d * * * 't NUCLEAR REGULATORY COMMISSION LPOR W.,i MC-REGION IV e
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ATTN:
J. M. Pilant, Director l'
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Gentlemen:
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The enclosed IE Information Notice provides early notification of an event that may have safety significance. Accordingly, you should review the Infonnation 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 question regarding this matter, please contact me.
Sincerely, z,
Karl V. Se'yfri u Director
Enclosures:
1.
IE Information Notice No. 80-45 2.
List of Recently Issued IE Information Notices cc:
L. C. Lessor, Superintendent Cooper Nuclear Station Post Office Box 98 Brownville, Nebraska 68321 8102280513 g
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SSINS No.:
6835 Accession No.:
801216002 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 IE Information Notice No. 80-45 December 17, 1980 Page 1 of 1 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 souNe, 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 oe 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 fcram 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.
IE Information Notice No. 80-45 December 17, 1980 LISTING OF RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued To Notice No.
Issued 80-38 Cracking in Charging 10/30/80 All Pressurized Water Pump Casing Cladding Reactor Facilities holding power reactor Operating Licenses (0Ls) and Construction Permits (cps) 80-39 Mal functiW,: Of Solenoid 10/31/80 All light water reactor Valves Manufactured By facilities holding Valcor Engineering Corporation power reactor Operating Licenses (OLs) or Construc-tion Permits (cps) 80-40 Excessive Nitrogen 11/7/80 All power facilities Supply Pressure with an Operating License Actuates Safety-Relief (0L) or Construction Valve Operation to Permit (CP)
Cause Reactor Depressuriza-tion 80-41 Failure of Swing Check 11/10/80 All power reactor Valve in the Decay Heat facilities with an Operating Removal System at Davis-License (0L) or Construction Besse Unit No. 1 Permit (CP) 80-42 Effect of Radiation 11/24/80 All power reactor on Hydraulic Snubber Fluid facilities with an Operating License (0L) or Construction Permit (CP) 80-43 Failures of the Continuous 12/5/80 All power reactor i
Water Level Monitor for facilities with an j
the Scram Discharge Volume Operating License (0L) at Dresden Unit No. 2 or Construction Permit (CP) 80-44 Actuation of ECCS in the 12/16/80 All power reactor Recirculation Mode While facilities with an in Hot Shutdown Operating License (0L) or Construction Permit (CP)
Enclosure L: