ML19305D656
| ML19305D656 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 04/08/1980 |
| From: | Janecek R COMMONWEALTH EDISON CO. |
| To: | Ippolito T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19262C724 | List: |
| References | |
| NUDOCS 8004150344 | |
| Download: ML19305D656 (3) | |
Text
F O, Chicago, lllir.ois 60690 Commonwealth Edison one First National Plaza. Chicago, Hlinois Address Reply to: Post Office Box 767 April 8, 1980 Mr. T. A.
Ippolito, Chief Operating Reactors - Branch 3 Division of Operating Reactors U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Oresden Station Unit 1 Fire Protection Modifications NRC Docket No. 50-10 Reference (a):
Letter from R.E.
Hall to R.L. Ferguson dated 2-20-80.
Dear Mr. Ippolito:
Reference (a) was transmitted to Commonwealth Edison by L. Derderian of the NRC Staff.
It deals with concerns identified during review of our Fire Protection designs for Dresden Unit 1.
Below are Commonwealth Edison's responses to those concerns:
Item 3.1.1 - Fire Detection Systems No detectors are located in the low consoles in front of the stand up panels in the control room.
In our review of the design for the Control Room it was determined that on the lower consoles there were 3 safety systems (HPCI, Core Spray and the Reactor Protection System).
Of those none were adjacent to each other, consequently, a fire in one safety system panel would not propagate to another safety system.
In addition, with the control room being manned at all times, the operator could quickly detect fires in the' lower consoles.
An area detection system is being installed over the whole Unit 1 Control Room Area, to detect fires in the lower consoles in time if the operator does not detect it first.
In addition, the solid suspended ceiling which was in place at the time of the NRC inspection is'being replaced by an aluminum " egg crate" ceiling which will freely pass smoke from the lower elevations in the I
room to the detection system at the ceiling.
Also the safe shutdown analysis demonstrates that, with the loss of the entire control room, the unit can be safely shutdown.
Therefore we feel the detection system as designed is adequate, and detectors F
so o41 sos 9st;
,J Canmonwealth Edison Mr. T. A.
Ippolito, Chief April 8, 1980 Page 2 in the lower consoles are not necessary.
Item 3.1.5 - Water Suppression Systems 1)
Automatic Preaction Deluge System - Cable Penetration Area a)
Note 3 on Drawing #26-1734 Sheet 1 states that design water flow is based on a.15 gpm. per sq. ft. over the entire cable tray surface area.
b)
Enclosed is another copy of Dwg. #26-1734 Sheet 1.
c)
One deluge valve is used to arm the preaction systems protecting the tunnel and the penetration.
An alarm from either detection system will arm both preaction systems.
Therefore it is felt our design is adequate from the stand point that if the fire propagates from one area to the other the second system will already be armed with water.
d)
The two motor operated valves are being looked at to determine if a fire in the area will isolate the supply to the penetration area.
This will be addressed at a later date.
e)
Heat collectors will be provided.
f)
Low air supervision will be provided.
2)
Drawings are enclosed.
3)
Automatic Deluge - Hydrogen seal' oil unit a)
A density of 0.25 gpm per sq. ft. over the entire surface of the tank will be provided.
b)
A remote actuation station will be located outside the entrance to the room.
4)
Automatic-Preaction Deluge System - Cable Tunnel a)
Spray Heads will be changed to the center line of the trays being protected.
b)
Low air supervision can not be done on this system.
The tunnel is not heated and is subject to below freezing temperatures.
To insure the system is dry at all times, thus preventing water from freezing in the pipes, each riser has a drain hole at its low point.
Parts 5, 6, 7 and 8 are acceptable.
L '.
Commonwealth Edison Mr.
T. A. Ippolito, Chief
. April 8, 1980 Page 3 9)
Extra Hazard Automatic Sprinkler - Clean and Dirty 011 Room 1)
The design density as shown on the hydraulic calculations is 0.30 gpm per sq. ft. over the entire room.
l Please address any questions you may have concerning this matter to this office.
One (1) signed original and thirty-nine (39) copies of this transmittal are provided-for your use.
Very truly yours,
[
Robert F.
Janecek Nuclear Licensing Administrator l
Boiling Water Reactors 2860A i
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