ML20044F790
| ML20044F790 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 05/19/1993 |
| 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 9306010053 | |
| Download: ML20044F790 (3) | |
Text
w
/
Ctmm:nwealth Edistn
(
O 1400 0 pus Place
\\s_ -} Downers Grove, Illinois 60515 O
-)
i May 19, 1993 i
Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulator'f Commission Washington, D.C.
20555 Attn:
Document Control Desk
Subject:
Commonwealth-Edison Company 10 CFR Part 21 Notification Related to Eagle Signal Control Timers
Reference:
(a)
May 6, 1993 letter from T.K.
Schuster to Dr. Thomas E. Murley
Dear Dr. Murley:
The purpose of this letter is to amend the attachment of the previously issued letter of Reference (a).
The amended attachment clarifies that Zion Station was the only CECO station involved-under
" Identification of Facility.and Component" versus the previous wording which simply stated "only station".
This is to clarify that CECO has no knowledge of whether the subject timers are being used at other
~l nuclear power stations in the United States outside of CECO.
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.
t Respectfully, i
hlfyg G.N Terence K.
Schuster Licensing Operations Director
Attachment:
10 CFR 21 Notification cc:
A.
Bert Davis, Regional Administrator - RIII C.Y.
Shiraki, Project Manager - NRR J.D.
Smith, Senior Resident Inspector - Zion g:ssmay:4 g,
,j 9306010053 930519 DR ADDCK 05000295 i
+
e IDEFR Part 21 Repart f
Eagle Sicual_Iimits i
'I Applicability This notification'is submitted in accordance with the requirements of 10CFR Part 21, Section 21, 21(a)(1).
ldantification of Facilitv and_CompanEn1 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 CECO station involved and l
has twelve (12) of these timers on each unit.
Iden11ffrat an_!2f_ Camp 2 nan 1_flanufanlurarLEupplint J
i Eagle Signal Controls 8004 Cameron Road Austin, Texas 78753 i
The components were procured as " commercial grade" and were dedicated for safety related application by Commonwealth Edison Company.
i Nature of Defect j
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 I refuel outage.
The binding of the timing assembly was due to inadequate clearance. All-clearances were not verified due to inadequate instructions from the i
manuf acturer, resulting in inadequate adjustment of the timers.
Safely _ 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.
Based on the significance of this defect, we believe it is reportable under 10CFR Part 21.
l l
t I
Ilme_of_ Discovery 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 Edison determined that this issue could be reportable under Part 21 on March 19, 1993.
j Number and Location of All Defective Components A review of our records indicated that a single purchase of twenty-seven (27) timers 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 maintenance work groups, with one remaining in the storeroom.
Zion Units 1 and 2 each have twelve (12) timers installed in the plant.
l Carrattive Actinna Clearances were adjusted to eliminate the mechanical binding observed in the eight (8) timers on Unit 1, which were then functionally tested and observed j
to reset properly. The remaining timers installed on Units 1 and 2 were I
inspected for mechanical binding (none was observed) and were verified to have reset properly, Revisions have been initiated to (1) the dedication testing j
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 installation instructions will-be completed by August 27, 1993.
Contacis Questions pertaining to the notification should be addressed to:
Douglas E. Paquette Engineering and Construction Commonwealth Edison Company 1400 Opus Place Downers Grove, IL 60515 (708) 663-2964 FGL/smv ZPWR/1233
______-__ ____.