ML19261B789
| ML19261B789 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities  |
| Issue date: | 02/02/1979 |
| From: | Reed C COMMONWEALTH EDISON CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-78-14, NUDOCS 7903060104 | |
| Download: ML19261B789 (3) | |
Text
Commonwealth Edison g,
One First Nabonal Plaza. Chicago lihnois Address Reply to: Post Office Box 767 Chicago. Illinois 60690 February 2, 1979 Mr. James G. Keppler, Director Directorate of Inspection and Enforcement - Region III U.S. Nuclear Regulatory Commission 799 Roosevelt Road Glen El),n, Illinois 60137
Subject:
Dresden Station Units 1, 2 and 3 and Quad-Cities Station Units 1 and 2 Response to IE Bulletin 78-14
" Deterioration of Buna-N Components in ASCO Solenoids" NRC Docket Nos. 50-10/237/246-and 50-254/265 Reference (a):
J. G. Keppler letter to B. Lee, Jr.
dated December 19, 1978
Dear Mr. Keppler:
Reference (a) transmitted IE Bulletin No. 78-14 regarding the deterioration of Buna-N camponents in ASCO solenoid valves.
In accordance with that bulletin, we have reviewed the use of Buna-N materials in our control rod scram systems.
Buna-N materials are used in the control rod drive scram pilot solenoid valves, backup scram solenoid valves, and the scram discharge volume vent and drain solenoid valves.
Except for a few solenoids which have been repaired or replaced, all are originally installed components.
Since these solenoids were installed as part of the original plant, no packaging dates are available for the internal camponents of the valves.
0 51979 79030601cDi
Commonwealth Edison NRC Docket Nos. 50-10/237/246 50-254/265
~
Mr. James G. Keppler: February 2, 1979 Our current plan for replacement and preventive maintenance at our units is to rebuild and inspect five percent (5%) of the ASCO solenoid valves at each refueling outage.
The backup scram valves will be included at the next refueling outages (current refueling outage on Quad-cities Unit 1), and at alternating refueling outages thereafter.
Any additional inspection and replacement will be based on the inspection results of these five percent of the valves.
Although this program will allow operation with valves which exceed the expected seven year life, we believe it is justified for the following reasons:
1.
Failures to date have been verv infrequent.
We have experienced no failures to scram due to Buna-N deterioration at Dresden or Quad-Cities Stations.
This includes almost nineteen years of operation at Dresden Unit 1, almost nine years of operation at Dresden Units 2 and 3, and almost eight years of operation at Quad-Cities Units 1 and 2.
2.
Our existing control rod drive surveillance program is adequate to detect any failures or drive performance degradation due to Buna-N materials deterioration.
A significant increase in the number of f ailures or drive performance degradation would necessitate a review of our preventive maintenance and replacement program.
3.
Even if a failure of an ASCO solenoid on an individual drive were to occur, operation of either of the backup scram valves would assure insertion of that drive in the event an actual scram condition existed.
4.
Full scale or accelerated replacement of these components would unnecessarily increase personnel exposure with no desonstrated increase in safety.
Commonwealth Edison NRC Docket Nos. 50-10/237/246
~
50-254/265 1
Mr. James G.
Keppler:
3-February 2, 1979 Based on the above, we believe our current replacement and preventive maintenance program is sufficient to ensure continued safe operation of our Dresden and Quad-Cities units.
Please address any questions concerning this matter to this office.
Very truly yours, k
Cordell Reed Assistant Vice-President