ML19211D147
| ML19211D147 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 01/09/1980 |
| From: | Crouse R TOLEDO EDISON CO. |
| To: | Reid R Office of Nuclear Reactor Regulation |
| References | |
| BAW-1564, NUDOCS 8001160569 | |
| Download: ML19211D147 (4) | |
Text
%
TOLEDO
%me EDISON A cwAmo P. C ACUSE Docket No. 50-346
.u o,wm uea License No. NPF-3 mm as saa Serial No. 572 January 9, 19 D 2 Director of Nuclear Reactor Regulation Attention:
Mr. Robert N. Reid, Chief Operating Reactors Branch No. 4 Division of Operating Reactors United States Nuclear Regulatory Commission Washington, D. C. 20555
Dear Mr. Reid:
This transmittal is in response to your staff's letter of November 7,1979 (Log No. 458) requesting additional information on " Integrated Control System Reliability Analysis" BAW Report 1564 dated August, 1979. The attachment identifies specific responses to your requests for the Davis-Besse Nuclear Power Station, Unit 1.
Where appropriate thase responses include currently projected schedules for activities not yet completed and bases for recommenda-tions not applicable to Davis-Gesse.
The Davis-Besse Unit 1 design provides safety grade auxiliary feedwater initia-tion and level control systems completely independent of the integrated control system. The current design in cor. junction with the attached response is considered appropriate action taken in light of the "L. 2 grated Control System Reliability Analysis" (BAW Report 1564).
Very truly yours, ffYh;a. -
RPC:TJM: cts g
5 g () O 1 16 0 %7 THE TOLECO EDISON COMPANY EDISON PLAZA 300 MADISCN AVENUE TOLEDO. CHIO 43652
RESPONSE TO NOVEHBER 7,1979 REQUEST ATTAti.IMENT TO TOLEDO EDISON COMPANY LETTER SERIAL 572 REQUEST FOR ADDITIONAL INFORMATION ON REPORT BAW-1564 For the following recommendations from Report BAW-156a
- Describe how you plan to implement the recommendation; and
- The schedule for hnplementation; or
- Basis for not implementing the recommendations at your plant.
1.
ICS RELATED a.
REQUEST NNI/ICS power supply reliability
RESPONSE
The Toledo Edison Company will pursue a study of powcr supply reliability to include both the ICS and the NNI internal power supplies and external power supplies.
We anticipate that the results of this study will be available by April, 1980.
b.
REQUEST Reliability of input signal from the NNI/RPS system to ICS specifically, RC flow signal.
RESPONSE
We have recognized the need for separation of the RCS flow signal used for control from the RPS, and have initiated the addition of a transmitter to provide a separate flow signal to the ICS.
We anticipate that this will be completed during the refueling outage currently scheduled for April, 1981.
c.
REQUEST ICS/ BOP system tuning particularly feedwater condensate sys-tems and the ICS controls.
i NOTE:
Although this concern is related to tuning, it appears that more h tsic design and/or operational problems in the feedwater (and related) system may exist.
Therefore, include a discussion of the following items:
(1) Any a-J.icular operational (start-up, etc.) problems expet;.ced at your plant with respect to the ICS.
Ref erence to previously submitted information is acceptable.
l
- RESPONSE At Davis-Besse Unit #1, we did experience problems related to the ICS tuning during the initial start-up period.
These are outlined in the Davis-Besse Nuclear Power Station Unit #1 initial start-up report which was transmitted to the Nuclear Regulatory Commission by letter Serial 1-18 dated May 8, 1978.
Specifically, we reference sections 8.1, 8.3 and section 12 of that report.
(2)
REQUEST Basis for operator intervention in place of automatic ICS action (start-up, power operation and shut down activities).
RESPONSE
The guidance given to operators for use of hand auto stations is included in the Davis-Besse Station Operating Plant Proce-dures PP1102.02, which is the station unit start-up procedure, and PP1102.10, which is the unit shut down procedure.
'\\
(3) REQUEST Additional Training Provided By The Operator
RESPONSE
Reactor operator training now includes, and has included in the past, sessions at the B&W simulator ehere the ICS f ailures of various kinds are simulated and the operator response is observed. This training has been modified since the TMI-2 incident to emphasize those actions to protect a system follow-ing a trip as a result of changes made which now initiate additional Reactor trips due to turbine trip.
2.
BALANCE OF PLANT a.
REQUEST Main Feedwater Pump Turbine Drive Minimum Speed Control - To Prever.t Loss Of Main Feedwater Or Indication Of Main Feedwater.
RESPONdE This is not a problem at Davis-Besse as the main feedwater control is accomplished by valve position as determined by ICS feedwater demand. The main feedwater pump minimum speed is fixed by a minimum speed setting.
b.
REQUEST A means to prevent or mitigate the consequences of a stuck open main feedwater start-up valve.
17Sif 171
. RESPONSE A study is presently on going to evaluate the consequences of over cooling of the reactor coolant system, and we anticipate the results of this study to be completed in January,1980.
c.
REQUEST A means to prevent or mitigate the consequences of a stuck-open turbine by-pass valve.
RESPONSE
Presently Davis-Besse Unit #1 has a safety grade steam and feedwater rupture control system which will, if necessary, isolate the main steam line should a low pressure occur as a result of a stuck-open turbine by-pass valve.
cg b/8-10 1756'172