ML20042C104
| ML20042C104 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood, 05000000 |
| Issue date: | 03/25/1982 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 3715N, NUDOCS 8203300207 | |
| Download: ML20042C104 (6) | |
Text
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N) one First National Plaza. Chicago.yos_s Ccmmonwealth Edison
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v,7 Address RIply to: Post Office Box 767
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/ Chicago. lilinois 60690 March 25, 1982 Mr. Harold R. Denton, Director
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Of fice o f Nuclear Reactor Regulation no U.S. Nuclear Regulatory Commission Washington, DC 20555
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Subject:
Byron Station Units 1 and 2 3
7) 6 Braidwood Station Units 1 and J.
W.4 a 'j SER Issues O '#
NRC Docket Nos. 50-454, 50-455, p1 50-456, and 50-457 0
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Dear Mr. Denton:
This is to provide information regarding radio repeaters and a summary of the auxiliary building flooding analysis for Byron and Braidwood.
Prompt review o f this information should close Outstanding Items 12 and 13(e) of the Byron SER.
Enclosed is the response to FSAR question 10.47 regarding drainage of leaking water away from safety-related equipment.
This response will be incorporated into the Byron /Braidwood FSAR in the next amendment.
Also enclosed it a discussion o f the consequences o f possible fire damage to the radio communication system used by the fire brigade.
No further action is planned regarding this item.
1 Please address questions regarding these matters to this office.
One (1) signed original and fifteen (15) copies o f this letter and the enclosures are provided for your use.
Very truly yours, O
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T.R.
Tramm
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Nuc ear Licensing Administrator g90 1m
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3715N 8203300207 820325 l
PDR ADOCK 05000454
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BYRON /BRAIDWOOD RADIO REPEATERS l
Byron SER Open Item 13e The SER states "The locations of repeaters used in connection with the radio system have not been determined.
The staf f will require the applicant to provide an emergency communication system in accordance with the guidelines o f BTP CMEB 9.5-1, Section C.S.g.
Section C.5.g (4) o f BTP CMEB 9.5-1 follows:
1 (4)
"A portable radio communications system should be provided for use by the fire brigade and other operations personnel required to achieve safe plant shutdown.
This system should not interfere with the communications capabilities of the plant security force.
Fixed repeaters installed to permit use of 4
4 portable radio communication units should be protected from exposure (to) fire damage.
Preoperational and periodic testing should demonstrate that the frequencies used for portable radio communication will no t af fect the actuation o f protective relays".
Response
The fixed repeaters for the portable radio communication units are housed in individual cabinets on the roo f of the instrument shop.
As shown on Figure 1.2-2 o f the FSAR, the instrument shop is located on the turbine floor (elev. 451') adjacent to the control room.
This area o f the plant does not contain any equipment required for safe shutdown.
A fire is assumed to occur in only one area of the plant at one time.
If a fire occurs in an area other than where the fixed repeaters are located, the portable radio communications system will be operable for the fire brigade and other operations personnel required to achieve safe plant shutdown.
If a _ fire occurs at the location of the fixed repeaters for the portable radio system, the plant will not be required to be taken to a safe shutdown condition.
However, direct voice communication between operations personnel in the control room and the fire brigade would exist because of the close proximity of the instrument shop to the control room.
Therefore, the Byron /Braidwood portable radio communications system is adequate to_ provide coordination of fire extinguishing activities between the fire brigade and other operations personnel required to achieve safe plant shutdown.
i 3715N
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QUESTION 10. 47_
i "Your response to Q10.30 has not provided an adequate analysis to demonstrate that drainage of leakage water away from safety-related components or systems is adequate for worst case flooding resulting from postulated pipe breaks or cracks in high or moderate energy piping near these safety-related components or systems.
The analysis must show that drainage by natural routes such as stair-wells or equipment or hatches by the non-seismic Category to I drainage system under failed conditions is adequate prevent the loss of function of safety-related components and systems.
As an example, show that a crack in one essential service water pump room will not flood out the other redundant pump before operator action can be taken to isolate the leak assuming a faile; non-safety grade sump alarm system.
Worst case locations should be assumed for this example and for other safety-related systems listed in FSAR Table 3.6-1.
"It is our position that unless drainage capability by natural or by failed non-seismic Category I drainage systems can be demonstrated, you should provide the following for all areas housing redundant safety-related equipment.
1.
Leak detection sumps shall be equipped with redundant safety grade alarms which annunciate in the control Verify that if operator action is required on room.
receipt of the alarm that flooding of redundant safety grade equipment.will not occur within 30 minutes; or 2.
Provide separate watertight rooms and independent drainage paths with leak detection sumps for each re-dundant safety-related component".
RESPONSE
A confirmatory analysis has been completed to insure that the Byron /Braidwood design will accommodate flooding as a result of high and moderate energy line breaks with no adverse effects on the capability to safely shut the plant down.
Design features such as enclosure of safety related equipment by structucal walls, separation of redundant safety systems, and drainage into atair-ways and open areas prevent a loss of safe shutdown capability in the event of moderate or high energy line breaks in the auxiliary building.
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The auxiliary building flooding study examined 114 separate areas in the auxiliary building.
20 of these areas were large general areas and the remaining 94 were considered subcompart-monts.
Subcompartments are enclosed by structural walls and open into other areas only by doorways.
The limiting high or moderate energy line break in each area was defined by surveying the lines in the area and determining the limiting failure.
Pipe breaks and cracks were defined following the guidelines in Standard Review Plan Section 3.6.1.
Maximum flood levels were defined for a break within an area and for breaks outside the area which might raise the flood level.
Fluids are considered to drain from subcompartments and general areas by way of doorways, stairwells, open hatches and floor drains.
Doors are considered to be open or closed to maximize the flood levels.
Non-watertight doors are assumed to have a 1/2 inch gap at the bottom.
The floor drain system in the Byron /
Braidwood plants is a. Safety Category II system but is seismically supported throughout the auxiliary building.
Credit is taken for the floor drain capacity since there-is no potential failure mode for a seismically supported drain pipe which would prevent--
drainage.
The auxiliary building'is equipped with leak detection sumps which will detect any leakage above normal rates.
Also, plant personnel regularly check the general conditions in the auxiliary building.
As a result, it is assumed that any isolable break is isolated 30 minutes after the break occurren_ce.
The analysis continues until maximum flood level is reached.
Of the 114 areas analyzed, 84 will not be subject to flooding greater than 4 inches deep.
Electrical equipment is located at least 4 inches above the floor to eliminate flooding concerns.
These areas, therefore, required no additional analysis.
The remaining 30 areas could experience water levels greater than 4 inches.
Of these, 17 would not flood above 12 inches and 13 were predicted to flood above 12 inches.
These 30 areas are primarily located in the lower levels of the auxiliary building.
These areas are individually discussed in the following paragraphs.
The auxiliary building basement is at Elevation 330'-0".
All rooms and areas on this elevation can be flooded to at least a depth of 12 inches.
As a result, these areas have been designed to accommodate flooding.
The floor drain sump and equipment drain pump rooms for Units 1 and 2 have been fitted with water-tight doors.
These rooms can be filled without affecting safe shutdown equipment.
The essential sersice water valve pits, if flooded would result in failure of the motor operated valves.
The ^
as-is position can be considered the safe position because the essential service water systems are redundant and separated by structural walls.
The general area contains the essential service i
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Page 3 t
water pumps and strainers.
The doorways and penetrations leading into this area are watertight and the structural walls are ade-quate to withstand the forces of flooding in adjacent areas.
In the event of a limiting crack of a 36" essential service water line within the area, a maximum flood level of 12 inches is pre-dicted.
In general, this will not disable the essential service water pumps.
Even if the system in the area is affected, there will be no impact on the redundant system which is separated by a structural wall.
On the 346'-0" level, flooding above the 4 inch level is predicted in four general areas and ten subcompartments.
A crack in a 48" essential service water line is predicted in the Unit 1 and 2 general floor areas which contain the blowdown condenser pumps, nitrogen storage.arca and various tanks.and motor control centers.
Mone of the equipment in this area is safe shutdown equipment.
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Two general piping areas which contain the auxiliary building collection sump pumps are located adjacent to the containments.
The area adjacent-to Unit 1 is predicted to flood to 12 inches after a 20. inch essential service water line failure. The area adjacent to Unit 2 is predicted to flood to 48 inches after a 48 inch essential service water line failure.
Neither of these areas contains safe shutdown equipment.
The subcompartments predicted to flood are the two RHR pump rooms, the two containment spray pump rooms and the valve operating area on each unit.
Upon failure of a 3 inch chemical and volume control system line, a flood level of 10 inches in the valve operating area cduld be expected.
No safe' shutdown e'quipment is in this area.
The residual heat removal pump rooms and containment spray pump rooms are all interconnected and all contain safe shutdown equipment.
The floor of these rooms is at Elevation 343', 3 feet below the general area.
The containment spray pumps are used only during accident conditions and, therefore, are not required under normal conditions as defined in the Standard Review Plan.
However, the containment pray pumps are elevated to prevent flood-ing from disabling the pump.
The RHR pumps are used during normal shutdown but are not required (except in LOCA conditions) to bring the plant to a safe hot shutdown condition.
In a normal shu tdown, the RHR system will be used when the reactor pressure is below about 400 psig to cool the reactor..At this time, a 16 inch RHR system line in the RHR pump room or a 24 inch Safety Injection System (RHR suction) line in the containment' spray pump room will be pressurized.
A failure of these lines would cause flooding up to the level of the 346' general area.
The subcompart-ments in question are located'at Elevation 343' so a flood of about 3 feet could be postulated.- The RHR pumps,. like the containment spray pumps, are elevated.well above the predicted flood level.
This also protects the pumps from flooding in the event a pipe in the general area fails and floods these subcompartments.
The
Page 4 only equipment which would be damaged by this flooding is the cubicle coolers.
This would cause a gradual increase in the room operating temperatures, but would not impair the ability to safely shut down the plant.
On the 364' level, three subcompartments per unit could be flooded.
A failure of an 18 inch non-essential service water line in the blowdown condenser room could result in a 40 inch flood level.
A failure of a 12 inch component cooling line in either residual heat exchanger room (A or B), would result in a flood level of approximately 100 inches.
There is no safety related equipment in the blowdown condenser room.
Flooding of a residual heat exchanger room would not affect the redundant train.
On-the 3 83 ' icvel, a crack in the 6 inch diesel oil piping in either Unit 2 diesel oil storage tank room would result in a flood level of less than 6 inches.
This would not af fect the other. tank or the plant safe shutdown capability. - A crack in the 20 inch non-essential service water line in either Unit 1 or 2 auxiliary feedwater diesel driven pump room would result in a 6 inch flood level.
This would have no effect on the re-dundant motor driven auxiliary feedwater pumps.
On the 401' level, a failure of a 6 inch chilled water line would result in a 5 inch flood level in the boric acid transfer pump No pump damage is expected and no safe shutdown equipment room.
will be affected.
Nonessential service water line failures could flood two of the radwaste surface condenser rooms to levels of 10 and 36 inches respectively.
No safe shutdown equipment is affected.
At Elevation 475 '-6", a failure cf a 4 inch fire protection line could result in up to 24 inches of water in cable spreading area E or K.
No damage is expected to the cables from a flood.
All cables with safety functions have redundant cables located in another cable spreading area separated by structural walls.
A 14 inch non-essential service water line located in a room contain-ing ventilation equipment and the chilled water expansion tank could result in a 21 inch flood level.
No safe shutdown equipment is in this area.
As a result of this study, it is concluded that flooding will not adversely affect the capability to safely shut down the plant.
The architectural design of the plant, the drain systems, the redundancy and separation of safety systems and the installation of water tight closures insure the plant safety.
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