ML20155G075
| ML20155G075 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 06/09/1988 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 1468, NUDOCS 8806170153 | |
| Download: ML20155G075 (2) | |
Text
,,
TOLEDO
%= EDISON A Cerstr Unrgy Cmpany j
DONALD C. SHELTON
[IE Docket No. 50-346 License No. NPF-3 Serial No. 1468 June 9j.1988 United States Nuclear Regulatory Commission Document Control Desk Vashington, D. C.
20555
Subject:
Steam and Feedvater Rupture Control System Modifications Gentlemen:
Toledo Edison's Course of Action (C0A), Appendix IV.C.2.2, dated September 5, 1985, (Serial No. 1182) detailed actions related to the Steam and Feedvater Rupture Control System (SFRCS).
Implementation of these actions vould improve the overall reliability of systems utilized for decay hest removal.
One of the planned actions was to delete the pneumatic relays in the control circuit of the Main Steam I.rolation Valves (MSIV).
It was concluded that the installed relay configuration was not testable and a failure vould not be readily detectable.
An undetected failure of one of the relays could cause a condition in which a partial or spurious system actuation vould.esult in an undesired MSIV closure.
Toledo Edison stated it vould remove the relays and replace the existing solenoid valves in each channel vith a larger solenoid valve containing position switches.
This was committed to be completed prior to beginning Cycle 6 operations.
Efforts to locate a vendor to provide larger solenoid valves with position switches qualified for this application have been unsuccessful.
The feasibility of relocating the solenoid valves to a milder environment has also been evaluated, however, due to the complexity of routing and sizing of the MSIV air lines to minimize the impact on the MSIV stroke time, this option has not been pursued.
Efforts continue to locate a vendor to provide the required qualified 4
The option of performing the required testing to qualify EO available solenoid valves is also being evaluated.
Due to these factors, Toledo
$@Q Edison has revised its plans that vould have implemented this modification prior 00 to beginning Cycle 6 operations.
Following completion of the necessary evaluations as noted above, we vill advise you of our plan and schedule on this a
commitment by January 31, 1989.
10 0 oO A review of previous operating history, conducted during the System Review and M
Test Program, indicated that pneumatic relay failures have not caused spurious as
- \\(
g MSIV closures.
Several other SFRCS design modifications have either been THE TOLEDO EDISON COMPANY ED! SON PLAZA 300 MAD: SON AVENUE TOLEDO, OH!O 43652
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Docket No. 50-346 License No. NPF-3 Serial No. 1468 Page 2 ccmpleted or vill be completed during the on-going refueling outage. These design modifications ensure that spurious closure of the HSIVs vill not be caused following momentary, short-lived SFRCS actuation signals similar to the one experienced during the June 9, 1985 event at Da,is-Besse.
It is noted that a single failure of one of the pneumatic relays by itself vill neither result in a spurious closure of the MSIV nor culminate in a failure of the MSIV to close in response to an SFRC3 signal. This is due to component redundancy in the valve control circuitry.
These relays are currently actuated during MSIV testing on an eighteen month frequency; however, they are not specifically monitored for actuation.
Based on the above, Toledo Edison believes its current plan to defer the above modifications is accep'.sble.
If you have any questions concerning this, please cal' Mr. R. V. Schrauder, Nuclear Licensing Manager, at (419) 249-2366.
Very truly yours,
{h/
JCS: tit ec:
DB-1 Resident Inspector A. V. DeAgazio, NRR Project Manager A. B. Davis, Regional Administrator
.