ML20036A495
| ML20036A495 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/06/1993 |
| From: | Schuster T COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| REF-PT21-93 NUDOCS 9305110339 | |
| Download: ML20036A495 (3) | |
Text
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) '.1400 Opus Place
( "^' ') Downers Grove, Illinois 60515
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l May 6, 1993 Dr. Thomas E. Murley, Director f
Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555 t'
Attn:
Document Control Desk
Subject:
Commonwealth Edison Company 10 CFR Part 21 Notification Related to.
Eagle Signal Control Timers
Dear Dr. Murley:
The purpose of this letter is to notify the NRC Staff of concerns by Commonwealth Edison Company (CECO) regarding failure of timers manufactured by Eagle Signal Controls to reset as expected.
These timers are utilized to sequence loads onto the emergency diesel generators at Zion Station.
Recently there were several occurrences of timers failing to reset during the conduct of operational testing due to mechanical binding.
Provided as.an attachment to this letter is CECO's notification in accordance with the requirements of 10 CFR 21,
-Section 21.
]
As stated in the attached corrective actions, CECO has adjusted
)L the affected timers to remedy the binding problem, inspected other:
installed timers to ensure binding is'not a concern, and initiated' changes to appropriate procedures to preclude further occurrences.
If there are any questions regarding this information, please direct them to Douglas E. Paquette at (708) 663-2964 or Stephen F Stimac at (708) 663-7275.
Respectfully, w-
-E-a f o F--
Terence K.
Schuster Licensing Operations Director-
Attachment:
10 CFR 21' Notification cc:
A..Bert Davis, Regional Administrator - RIII-C.Y.
Shiraki, Project Manager.- NRR g:ssmay:4 incri s pa5TAPSjes
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n; ce lQ.CFR Par _t 21 Rep.oit Eagle Signal Timers Applicability This notification is submitted in accordance with the requirements of 10CFR Part 21, Section 21, 21(a)(1).
Identification of Facility and Component This notification concerns Eagle Signal Controls polyflex timer part
- HO-64-A6-02.
These timers are used to sequence loads onto the emergency-diesel generators at Zion Station.
Zion is the only station involved and has twelve (12) of these timers on each unit.
Identification of Component Manuf_acturer/ Supplier Eagle Signal Controls 8004 Cameron Road Austin, Texas 78753 The components were procured as " commercial grade" and were dedicated for safety related application by Commonwealth Edison Company.
Neture of Defect There were several occurrences of timers failing to reset during the conduct-of periodic testing.
The failure to reset was caused by mechanical binding in the timer assembly, which was observed to some degree in eight (8).of the twelve (12') timers installed on Unit 1.
All twelve (12) timers had recently.
'been installed during the last Unit 1_ refuel outage.
The binding of.the timing assembly was due to inadequate clearance..All clearances were not verified due to inadequate instructions from the manufacturer, resulting in inadequate adjustment of the timers.
Safety Significance
.The timers are used to sequence loads on to the emergency diesel generators.
The degree of mechanical binding which was observed would not have prevented proper timer actuation, and-the loads would have been sequenced'onto the emergency diesel generators as designed. However, failure of a timer to reset
-(had it remained undetected) could have prevented proper' equipment' operation the-next time the timer was called upon to actuate. Certain undesirable combinations-of failures combined with a design basis LOCA, could have-resulted in the_ availability of.less than the minimum complement of ECCS and/or other equipment assumed to-function in the safety analyses.
L Based on the significance of this-defect, we believe it is reportable under
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-i Time of Discovery j
Following receipt of new information from Eagle Signal Controls regarding pre-and post-installation clearance checks which should be. performed to ensure-proper timer reset capability, Commonwealth EdisonLdetermined that this issue l
could be reportable under Part 21 on March 19, 1993.
Humber and Location of All Defective Components A review of our records indicated that a single purchase of twenty-seven (27) tbners occurred in June, 1992. These timers subsequently underwent dedication testing at our Central Receiving, Inspection and Test (CRIT) facility.
Following their shipment to Zion, twenty-six (26) of these were issued to the.
i maintenance work groups, with one remaining in the storeroom. Zion Units-l~
and 2 each have twelve (12) timers installed in the plant.
Cattentive Actions
'i Clearances were adjusted to eliminate the mechanical binding observed in the eight (8) timers on Unit 1, which were then functionally tested and observed to reset properly. The remaining timers installed on Units 1 and 2 were inspected for mechanical binding (none was observed) and were verified to have reset properly. Revisions have'been initiated to (1) the dedication-testing procedures and (2) the installation adjustment. instructions for the timers, to perform additional pre-and post-installation checks. As of this date, the revisions to the dedication testing procedures at the CRIT facility have been completed.
The revisions to Zion Station's insta17 ation instructions will be.
completed'by August 27, 1993.
Condnis Questions pertaining to the notification should be addressed to:
Douglas E. Paquette Engineering and Construction
- l Commonwealth Edison Company 1400 Opus Place Downers Grove. IL 60515 (708) 663-2964 9
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