ML17174A292
| ML17174A292 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/29/1979 |
| From: | Janecek R COMMONWEALTH EDISON CO. |
| To: | Oconnor P Office of Nuclear Reactor Regulation |
| References | |
| TASK-09-03, TASK-9-3, TASK-RR NUDOCS 7912310361 | |
| Download: ML17174A292 (6) | |
Text
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Commonwealth Edison One First National Plaza, Chicago. Illinois Address Reply to: Post.Office Box 767 Chicago, Illinois 60690 November 29, 1979 Mr. Paul O'Connor, Project Manager Operating Reactors - SEP Branch U.S. Nuclear Regulatory Commission Washi~gton D.C.
20555
Subject:
Transmittal of Requested Information on SEP Topic IX~3, Station Service and Cooling Water Systems Dresden 1 & 2 NRC Docket 50-10/237
Dear Mr. O'Connor:
In response to your requests concerning the above referenced topic the following information is being provided.
Dresden 1 Question 1:
Response
What is the minimum river level at which the service water, screen wash, and fire protection pumps remain operable?
Se~vice water, screen wash, and fire protection pumps will remai~
operable with a river level down to 489' 10".
Question 2:
Response
How much residual heat (metal and water) is released during a cooldo~n from normal operating temperature to 212 F?
The total re~idual heat in the reactor system is approximately 475.3 millio~ BTU.
Mass of equipment and water during normal operati~n was obtained from e~uipment manuals.
Temperatures were estimates from operating records.
Question 3:
What functions are performed by the following and what are the effects of failure of the function?
a) b)
c) d)
Post incident pump lube water.
Bearing lube water for the service, screen wash, and fire pumps.
Service W~ter System (SWS).to control room air SWS to re~ctor enclosure air conditioning.
conditioning.
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I Question 3 (Cont'd)
Response
e)
Reactor enclosure cooling water to recirc. pump motors.
f)
Reactor enclosure cooling water (RECW) to reactor shield cooling coils.
g)
RECW to reactor isolation cooling unit.
h)
RECW to secondary steam generator room coolers.
a)
Post incident pump lube water system provides a supply of de-mineral ized water to the post incident pump bearings for lubrication.
Failure of this system will eventually.lead to a failure of the post incident pumps.
b)
Bearing lube water system for service, screen wash, and fire pumps supplies a sou~ce of well water to the pump bearings for lubrication.
Failure of this system will eventually lead to a failure of the pumps.
c)
Service water system to control room air conditioning supplies cooling water to two condenser units.
Loss of this system would result in the loss of cooling to various zones in the Unit One control room.
This would most likely lead to high instrument temperatures in the area.
d)
Service water system to reactor air conditioning provides cooling to the chilled water system.
Loss of service water would lead to loss of room cooling capabilities in instrument rooms and area coolers (K fans).
e)
Reactor enclosure cooling water to recirc. pump motors limits motor temperature 1S0°F.
Loss of flow to the cooling heat
. exchanger is annunciated in th~ control room.
If action is not taken, motor failure will result.
f)
Reactor enclosure cooling water to reactor shield cooling coils removes radiant heat loss from the reactor during operation.
Loss of this system would result in high ambient temperatures in the rea~tor annulus area.
g)
Reactor isolation cooling does not exist on Dresden 1.
h)
RECW to SSG room coolers provides cooling water to room air movers.
Loss of this system would result in high roo~
temperature.
Question 4:
What are the required operator actions for loss of SWS, RECW, TBCCW Systems? :Are these actions covered by procedure?
I*.
Response: Procedures for loss of SWS, RECW, and TBCCW are covered by DOA 3900-1, 3700-1, and 3800-1, respectively.
In all instances, a stand-by pump automatically starts.
Reactor power is reduced or the reactor is shut down, depending on the severity of the incident, and action i~ taken to isolate ariy failures.
Question 5:
- Response:
What is the source of cooling for the diesel generato~?
New Unit One ESAP diesels are cooled by skid mounted air cooled radiators.
HPCI diesels are cooled with water taken from the HPCI water storage tank.
Question 6:
Response
Dresden 2 Since the fire water system supplies the core spray system why is it not classifed as safety class 2 in your ISi Program?
The fire water system was originally designed and constructed in the late 1950's to be a fire water system.
The core spray system which takes its w~ter supply from the fire wat~r system was designed in the eariy 1970's.
When the. fire water system was originally designed it's use as a water supply to the core spray system was not envisidned.
As a result, the fire water system was constructed in such a manner that it is not possible for it to be in~pected as a* safety.class 2 system by the ISi Program.
However, the system was classed as safety class 3 for ISi purposes, which imposes requirements beyond the original requirements on the fire water system.
Commonwe~lth Edison's detailed submittal on the core spray system was made by Henry E. Bliss to Dr. Peter A. Morris on September 17, 1970.
This document stated the design basis and ISi require-ments for the emergency core cooling system.
Question 1:
How much residual heat (metal and water) is released during a cool down ffom normal operating temperature to 212°F.
Response
- The energy balance was performed for a constant volume control system including the RPV, the reactor internals, the fuel, all auxiliary piping (recirc loops, main steam lines, RHR shutdown system LPCI, HPCI and co~e spray systems) back to the temperature drops below 2120F, and the isolation condenser.
An initial temperatur~ of 5460f was assumed for all but the feedwater system where lower initial temperatures were available for each section considered.
All final conditions were taken 2120F.
Total heat released (excluding decay heat) - 3.55 x 108 BTU Total heat released including decay he~t is illustrated by Graph 1.
Question 2:
Response
What is the m1n1mum river level at which the service water and and the diesel cooling water systems remain operable?
The response to Question l~F in Amendment 9 to the Dresden 2 FSAR indicates that in the event of a postulated unusual drop in river water level, water would still be impounded in the Dresden 2 & 3 intake canal to a level of 495 feet 0 inch:
."Due to the topography of the circulating water canals and piping, approximately 9,000,000 gallons of river water is trapped within the system~
This is due to the high points in both the intake and ~ischarge canals.
As the Dresden pool level would fall, back flow from the discharge canals would stop at 498 feet 0 inch, and from the intake canals at 495 feet 0 inch.
Advantage can be taken of this impounded river water as a heat sink for a long term removal of decay heat from the reactors.
The s~ctions of the service water pumps for Units 2 & 3 are below elevation 495 feet 0 inch, therefore, a service water pump could be valved to supply cooling water to the reactor building closed coolin~ system which, in tur.n, would be discharged to the discharge canal to dissipate its heat to the environs.
The water in the discharge canal would then be r~circulated back to the intake canal through the deicing line.
Operation of the Units 2 & 3 diesel generators is assured since the suction for their cooling water pumps are at 487 feet 8 inch~s.
The diesel fire ~ump of Units 2 & 3 has its suction at 492 feet 0 inch.
Loss of impounded river w~ter, due to evaporation, could be made
~p by use of portable low head, high volume, engine-driven pumps.
Commonwealth Edison has six 1500 gpm engine-driven pumps oh standby at various fossil fuel generating st~tions.
These pumps could be moved to Dresden within six hours.
Pumps are also availabl~ from large contrattors in the northern Illinois area."
Thus, operability of the service water and diesel cooling water. systems is assured independent of river water level.
Question 3:
Response:*
What functons are performed by the following and what are the effects of failure of the function:
a)
RBCCW flow to the recirculation pumps?
b)
TBCCW to reactor feed pumps?
c)
TBCCW to control rod drive water pumps?
d)
SWS to control room air conditioning?
e)
SWS to aux. elect. equtpment room air conditioning?
f)
SWS to diesel gen. cooling water pumps?
a) b)
c)
RBCCW supplies cooling GPM) and the pump seal to the pump and motor, imately one (1) minute damage.
TBCCW supplies cooling coolers {59 GPM/pump).
should be removed from damage to the pump.
water to the motor assembly (50 GPM).
the pump should be to prevent bearing oil cooler (10 If RBCCW is lost tripped in approx-and/or seal water to the reactor feed pump oil If TBCCW is lost to a pump, the pump service as soon as possible to prevent TBCCW supplies cooling water to the CRD water pumps at a rate of 2 GPM/pump.
This cooling water cools the thrust bearing housing jacket.
If cooling water is lost the pumps should be removed from service as soon as possibie to prevent damage to the pumps.
d & e)
SWS supplies cooling water to the air conditioners cooling condensers.
If water is lost to the air conditioners, the units should be secured to prevent equipment damage.
f)
The bearings and water jackets of the DG cooling water pumps are cooled by water externally piped from the discharge of the pump.
They are not cooled by service w~ter.
Que s t.i on 4 :
Response
What are the ~equired operator actions for the loss of RBCCW, TBCCW, and SWS?
Are these actions covered by procedures?
Operat6r action for loss of RBCCW, TBCCW and SWS are covered by the attached procedures 3700-1, 3800-1, and 3900-1 respectively.
Question 5:
Response
What is the through wall thickness of. the 42 11 di a *. common SW pump discharge heat~r in the crib house?
Per S&L Spec. K-2202 for Dresden 2 & 3, SW Pump discharge header.
2/3-3901-42 11 -0 has a wall thick11ess of 3/8 11
- Question 6:
Response
Do backup cooling methods exist for control room and auxiliary electric room air conditioning?
There are no backup cooling methods for the control room 'and auxiliary electric room air conditioners.
Th~ station, however, has installed a modification which would allow going open cycle should the control room air conditioner fail.
This allows outside air to be drawn through filters into control room and auxiliary electric room, then exhausted back to the outside.
Question 7:
Response
What is the quality and seismic classification of the diesel generation cooling water and the containment cooling service water systems?
Chapter 12 of the Dresden 2 & 3 FSAR designates the diesel generator cooling water and LPCI/Containment Cooling Service Water System~ as Seismic Class I.
Dresden 2 was built before Quality Group Classifications were instituted.
Per Regulatory Guide 1.26, these systems would be designated Quality Group C.
Question 8:
What equipment is cooled by the reactor building emergency air
- coolers which ar~ supplied by diesel gen. coo]ing water?
Response
911A The emergency air coolers are located in the HPCI, Core Spray and LPCI rooms.
The emergency air coolers cool the air in the rooms which in turn cools all the equip~ent located in the rooms.
The emergency air cooler's.water supply has been modified to allow the use of either service or diesel generator cooling water.
Our studies show we can operate for prolonged periods without the e~ergehcy air coolers i~ service.
Very truly yours,
. /1 ~:r. Jt;_J;r;_
- . LL R. F. J a n~t e k
-~*-
Nuclear Licensing c*
Administrator Boiling Water Reactors