ML17320A927
| ML17320A927 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 12/23/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17320A926 | List: |
| References | |
| NUDOCS 8402010124 | |
| Download: ML17320A927 (18) | |
Text
Safet Evaluation
-".nc la",ur ~
f5~iE Donald C.
Cook Nuclear Power Plant Uni ts Ho.
1 and 2
Oocket Hos.
50-31S/315 1.0 Introduction By letters dated Oecember 30,
- 1982, March 31, 1983 and August 22,
- 1983, the licensee requested exemptions fror Section IrI.G and 1 exemption from Section III.O of Appendix R to 10 CFP, 50.
Section III.G.2 requires that one train of cables and equipment necessary to achieve and maintain safe shutdown be maintained free of fire damage by one of the following means:
Separation of cables and equipment and associated non-safety circuits of redundant trains by a fire barrier having a 3-hour rating.
Structural steel forming a part of or supporting such fire barriers shall be protected to provide fire resistance equivalent to that required of the bar rier; Seoarat'on of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 0 rect with no :ntervening corneous'.loie~
or 'ire hazards In adition, fire detectors and an automatic f.re suppression system sha)1 be installed in the fire area; or Enclosure of cables and equipment and associated non-safety circuits of one redundant train in a fire barrier having a I-hour rating.
In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
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I
If these conditions are not met,Section III.G.3 requires alternative shutdown capability independent of the fire area of concern.
It also requires a fixed suppression system in the fire area of concern if it contains a large concentration of cables or'ther combustibles.
These alternative requirements are not deemed to be equivalent for'll configurations,
- however, they provide equivalent protection for those configurations in which they are accepted.
Because it is not possible to predict the specific condit'.ons under which fires may occur 'and propagate, the design basis protective features are specified in the rule rather than the design basis fire.
Plant specific features may require protection different than the measures specified in Section III.G.
In such a case, the licensee must demonstrate, by means of a detailed fire hazards
- analysis, that existing protection or existing protection in conjunction with proposed modifications will provide a level of safety equivalent to the technical requirements of Section III.G of Appendix R.
In summary,Section III.G is related to fire protection features for ensuring'hat systems and associated circuits used to achieve and main-tain safe shutdown are free of fire damage.
Fire protection configura-t'.ons must either meet the specific requirements of Section III.G or alternative fire protection configurations must be justified by a fire hazards analysis.
Our general criteria for accepting alternative fire protection con-figurations are the following:
The alternative assures that one train of equipment necessary to achieve hot shutdown from either the control room or emergency control stations is free of fire damage.
The alternative assures'that fire damage to at least one train of equipment necessary to achieve cold shutdown is limited such that it can be repaired within a reasonable time (minor repairs with components stored on-site).
Modifications required to meet.Section III.G would not enhance fire protection safety above that provided by either existing or proposed alternatives.
Modifications required to meet Section '.II.G would be detrimental to overall facility safety.
Section III.O of Appendix R to 10 CFR Part 50 requires that the reactor coolant pump shall be equipped with an oil collection system if the containment is not intended during normal operation.
Section III.O also requires, among other. things, that the leakage shall be collected and drained to a vented closed container that can hold the entire lube oil system inventory.
2.0 RHR/CTS Pump Area (Fire Zone 1)
Z. 1 Exemption Requested An exemption is requested from Section III.G to the extent it requires an automatic suppression system for the protection of redundant equipment separated by greater than 20 feet free of intervening combustibles.
Z.
Oi'scussion l
Fire Zone 1 is located in the east central sub-basement floor of the A xiliary Building at el.
573 ft.
The area contains eight individual
.cubicles containing the redundant residual heat removal pumps and con-tainment spray pumps for both units.
Each pump cubicle has a controlled access screen mesh door which is located behind a missile shield wall.
The cubicles are separated from each other by three-hour rated walls.
The Unit 1 pumps are separated from the'Unit 2 pumps by approximately 23 ft,between the walls forming the entrance way.
~ The floors and ceilings are also of three-hour construction.
The access doors are screen mesh for ventilation purposes;
- however, the missile shield walls extend beyond the width of the doorway.
The pump cubicles are provided with curbs six inches high and floor drains.
The suction valves for the pump in each cubicle are located behind part-height missile shield walls provided with an access way and curb forming part of the missile shield.
The center lines of the RHR pumps are located approximately 12 feet from the entrance ways of the cubicles and approximately 4 feet from the wall dividing the pumps for each unit.
Manual fire suppression equipment and a detection system are provided in the area.
The fire load in the area is low.
The licensee proposes to upgrade the walls between the redundant pumps to a
3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire resistance rating by sealing all penetration:openings and installing fire dampers in common HVAC duct work." Onetrain of power cables will be enclosed in a 1-hour rated barrier.
3.0 Evaldation This area does not comply with Section III.G becuase it does not have automatic suppression, the enclosures from the RHR pump are not fire
- barriers, and the unprotected pump power cables are located less than 20 feet from each other.
The combustible loading in this area is low.
An early warning smoke detection system is provided.
If a fire occurred in this area, it is our opinion that the 3-hour walls between the RHR pumps and 1-hour barrier on one train of cables in the corridor will provide reasonable assurance that one train of RHR pumps will be maintained free of fire damage in the interval needed for the fire brigade to respond and manually extinguish the fire.
4.0 Conclusion Based on the above evaluation, the existing protection for the RHR pumps in conjunction with the proposed fire barrier modifiCations provide a
level of fire protectioh equivalent to the technical requirements of Section III.G.
The exemption
- should, therefore, be granted.
5.0 Unit 1 and Unit 2 Transformer Rooms '(Fire Zones 14 and 20)
- 5. 1 Exemption Requested An exemption is requested from Section III.G to the extent it requires a fixed suppression system in an area where alternative shutdown cap-ability is provided.
5.2 Discussion These fire zones have three-hour-rated walls, floor and cei ling.
Except for two 1-1/2-hour dampers to the Turbine Building, the barriers bounding these fire areas are entirely three-hour rated.
These areas contain the pressurizer heater transformers, which are located approxi-mately 12.'feet apart and the emergency diesel test breakers..
Access to the area is through an unlabeled door built to three-hour specifications, approximately 12 feet wide, which faces the Turbine Room in the 'Nest wal l.
The two fire zones are separated by several hundred feet.
If a fire occurred in either area, the equipment of one unit could be used to safely shut 'down the other unit.
Manual fire suppression equipment is provided in the area.
The licensee proposes to install a detection system in the area.
- 5. 3 Eyal uati on These areas do not meet Section III.G because fixed suppression systems are not provided.
Section III.G requires a fixed suppression system if the area contains a large concentration of cables or other combustibles.
These two areas contain primarily electrical equipment in metal cabinets, and have a
low in-situ combustible loading.
With a detection system installed as proposed, a fire in either of these areas would be of limited severity and duration.
The installation of a fixed suppression system would not appreciably enhance the fire protection for safe shutdown capability.
5.4 Conclusion Based on the above evaluation, with the proposed modification, the fire protection system for the transformer rooms of Unit 1 and 2
provides a'level of protection equivalent to the technical requirements'f Section III.G and therefore, the exemption should be granted.
6.0 Unit 1 and Unit 2 Essential Service Mater Pumps 8 Motor Control Centers (Fire Zones 29 a, b, c, d, 8 f).
6.1 Exemption Requested An exemption is requested from Section III.G to the extent it requires a fixed suppression system for an area where alternative shutdown capability has been provided.
6.2 Discussion At elevation 591'" of the screen
- house, there are two rooms, separated by a 3-hour. rated fire w'all.
Each room contains the Essential Service Mater (ESW) pumps and motor control centers of their respective units.
Access to the pumps is through the side access control gate from the
screen house area..
The access gate is constructed of screen mesh for ventilation purposes.
The pump cubicles share a
common corridor with a wall separating the Units 1 and Unit 2 pumps.
A missile shield perendicular to the wall partially encloses the pumps.
The pumps are installed on pedestals approximately four feet off the ground.
The wall separating the Unit 1 zone from the Unit 2 zone is three-hour rated.
The fire load in the area is low.
The ESW pumps are not separated from each other by complete 3-hour rated fire barriers.
An open stairway and open vertical hatch to the room below the pumps violate the integrity of the 3-hour barriers.
This exemption request is limited to the need for a fixed suppression system in the ESW pump rooms.
Manual suppression equipment is provided in the area.
The licensee proposes to install a detect'ion system throughout the area.
6.3 Evaluation This area does not, comply with Section III.G because a fixed extinguish-ing system is not provided.
The ESW pumps of one unit can be used as a backup for the other un'it.
Section III.G requires a fixed suppression system if the area contains a large concentration of cables or other l
combustibles.
In this area, the only combustibles are a few cables and the 2 gallons of lubricating oil from the pump motors totally enclosed in the pump casing.
With a detection system installed, as
- proposed, a fire in either of these areas would be of limited severity and duration.
The installat'ion of a fixed suppression system would not appreciably enhance the fire protection for safe shutdown capability.
6.4 Conclusion Based on the above evaluation, with the proposed modifications, the fire protection for the ESW pumps of Units 1 and 2 provides a level of protection equivalent to the technical requirements of Section III.G and therefore, the exemption should be granted.
7.0 Circulating Water Pump Motor Control Room (Fire Zone 29G) 7,1 Exemption Requested An exemption is requested from Section III.G to the extent it requires 3-hour barriers for the boundaries of fire areas, and the installation of automatic suppression in areas where redundant trains of safe shut-down cables are routed.
7.2 Discussion
, Fire zone 29G is the basement level below the essential service water pump rooms of both units and contains two non-safe shutdown motor control centers.
The fire zone has an open hatch with a ladder up to the Unit 2 ESW southeast pump cubicle and a stairway which opens to the northwest Unit 1
pump cubicle.
The ceiling and walls are all three-hour rated.
With the exception of the four ESW pump power cables and conduit for the Unit l. east pump gdischarge valve, all the conduit comes through the wall in pull boxes near the ceiling and immediately exits up into the ceiling slab.
The cabling into the ceiling runs in embedded con-duit to its respective pump cubicle.
All ceiling and wall pene-trations are sealed with three-hour rated fire seals.
The licensee now proposes a different modification involving the open hatchway.
Previously, a one-hour rated hatch was proposed.
- Now, a 3-hour rated hatch is proposed.
The Unit 1
and Unit 2 ESW pumps will therefore be separated by a complete 3-hour barrier in compliance with Section III.G.
In addition, the arrangement of the stairway and exhaust ventilation system provides a means for high"level venting of. smoke,
- heat, and combustion products ema" nating from fire zone 29G.
This will preclude a buildup of a hot gas layer at the ceiling level in fire zone 29G where the ESW
The wal 1 s, floors, Excluding doors to fire rating of one damper s.
and ceilings are'.of reinforced concrete construction.
the exterior. of the.area, all barriers have a minimum hour.
Ventilation ducts are not provided with fire The combustible loading in the area is low.
'Alternate shutdown capabilit apaiiy is provided independent of the areas.
The licensee proposes to install a detection system and 1-hour rated fire dampers.
B. 3 Evaluation
'hese areas do not comply with Section III.G because a fixed suppression system is not provided.
Section iii.G requires a fixed suppression system if the area contains a high concentration of cables or other combustibles.
These areas contain primarily cable insulation, however the amount of insu'i ati on i s di stributed throughout the ar ea and in its present con-figuration does not pose a significant hazard.
With a detection system install'ed, as proposed,
.a fire in either of these areas would be of limited severity and duration.
The installation of a fixed suppression system would not appreciably enhance the fire protection for safe shut-down capability.
8.4 Conclusion Based 'on the above evaluation, with the proposed modification, the fire pro ection system for the Unit 1 and Unit 2 main steam enclosures provides a level of fire protection equivalent to the technical requirements of Section III.G.
The exemption should, therefore, be granted.
9.0 Component Cooling Water Pump Area (Fire Lone 44S) 9.1 Exemption Requested An exemption is requested from Section III.G to the extent it requires the enclosure of one train of redundant safe shutdown cables and equipment in a 1-hour rated barrier, or separation of redundant trains by complete 3-hour rated barriers.
9.2 discussion This zone is the south hal f of el. 60S'"
o) the Auxiliary Building and contains a number of Unit 2 safe shutdown cables, five component cooling water (CCW) pumps, two Unit 2 CCW heat.excnangers, and associated valves.
The CCW pumps are mounted on 4-inch high pedes-tals with 6-inch high concrete curbs completely surrounding the pedes als.
Ventilation exhaust ducts are located ove.
each motor which completelv cover the pump.
The Unit l eas.
anc Unit 2 wes.
Dumos a
the motor enc Sea. ings are scca". atec bv aoprox:mat.eiy 5 ft., while the Unit 1 west pump motor, to Unit 2 west pump moto'r is separated by approximately 16 feet.
The five CCW pumps are all located within a section of approximately 35 ft by 35 ft.
The ceiling height in this area is approximately ll feet.
The Unit 2 CCM heat exchangers run north and south and are approximately 12 feet north of the Unit 1 east pump and separated from each other by approximately 7 feet.
At the north'end of the Unit 2 CCW heat exchangers are the heat exchanger outlet valves approxi-mate'ly 75 feet from the south wall.
A detection system and a partial suppression system are currently
.provided in the area.
The licensee has proposed to extend the suppression system to cover the CCW pumps.
The additional suppres-sion will consi st of ceiling-mounted sprinklers located for direct water application onto the pumps.
Detection will consi st of pilot head heat detectors also located directly over the pumps.
The ceiling-mounted sprinkler s cover approximately 65 sq ft per head and will provide a design density of 0.4 gpm/sq. ft.
Orainace capaoi 1 i:y in the vicini:> or '.ne Dumps cons is:5 Q'
a)il openings on each of the five pump pedestals and a grid o) diameter drains covering the'ntire floor area of "-'.re 'one
-'-'S.
Adequate capacity is provided for drainage of suppression wat,er
/
resulting from a fire in this zone.
/
12 A partial height three-hour rated fire barrier will be provioec
'o separate redundant component cooling water pumps.
The barrier will be seismically qualified and constructed of insulated panels.
The panels will be overlapped to provide protectionfoz
.5he bol~
attaching the panels to the metal studs.
The proposed barrier will be approximately six feet-six inches in height, and will extend 39 feet from the rear wall of the plant.
The effect will be =" separate the
~Jnit l pumps
',rom the Unit 2 pumps, anc separate the spare pumj from all four pumps.
Two ceiling elevations exist in Fire Zone 445.
The clear floor to ceiling height over the component cooling water pumps is 10-ft ll-in., with that over the rest of the fire zone being 20-ft 4-in.
Because of the change in ceiling elevations, the products of combustion from a fire in the vicinity of the pumps would tend to flow up into the 20-ft 4-in, high cei ling space, and prevent a stratified layer of hot gases from forming over the
=o'>oonent coolino water oumps.
=;a i a.';on This area does not comply with Section III.G because the redurd t CCM systems are not separated by 3-hour rated fire barriers.
The licensee proposes to install an increased coverage automatic suppression system over the CCM pumps and to separate the pumps.
=- "artial height."-hour starrier.
t<<,
,as
- ,1,-,;,
- ,
~ that due to ".he low ceiling, and close proximity o'edundant equipment a
.i e in this area cou'ia damage a1l CCh'umos
.'or rot," units. prior
- o response of the fire brigade.
The partial height barrier wi11 prevent a floor leve! ei,.os~re fire from damaging redundant CCM pumps.
A stratified lave of
13 hot combustion gases will not form in the area immediately above the pumps due to the high level venting provided by the change in ceiling height in the area adjacent to the pumps.
In addition, a high density sprinkler system will be provided over the
- pumps, with extended coverage heads provided at the height of the pumps, as well as the cei ling.
This combination of protection provides reasonable assurance that one train of CCM pumps will remain functional until the response of the fire brigade.
9.4 "Conculsion Based on the above evaluation, the level of existing protection in conjunction with the proposed modifications provides a level of fire protection for the Component Cooling Mater Pump Area (Fire Zone 445) equivalent to the technical requirements of Section III.G.
The exemption should be granted.
10.0 Unit 1 and Unit 2 Control Rooms (fire areas 53 and 54) 10.1, Exemption Requested An exemption is requested from Section III.G to the extent it requires a
fixed suppression system in an area where alternate shutdown capability lias been provided.
10.2 Discussion These fire areas are the Control, Rooms for Units 1
and 2.
The Control Rooms contain all the normal control panels for plant operation and most relay and instrument cabinets associated with plant control.
In addition, the Unit 2 hot shutdown panel is located in the south-west corner of the Unit 1 Control Room and vice versa.
The top of the panel is approximately eight inches from the false cei ling of the control room.
The hot shutdown panel is of steel construction with a folding steel door at the front of the panel.
~14-The control room area is protected from other fire zones by three-hour rated floors, ceilings and walls except for 2 ceiling and 2 floor
- hatches, both of which have two-hour ratings.
Also, the common con-necting door between the control'rooms is unrated.
There are ionization detectors located in each control room.
Loc'ated outside the control room are water hose reels.
Inside the control room are six C02 fire extinguishers and two 1-hour breathing apparatus.
Two G02 hose reels are located outside the fire ar ea.
The licensee proposes to upgrade
. the two floor hatches and the common connecting door to a 3"hour rating.
Alternate shutdown capabi1i ty is provided independent of each control room.
10.3 Evaluation This area does not comply with Section III.6 because the control room is not provided with fixed suppression.
The control room is equipped with area fire detectors and is provided with both 'a hose station and fire extinguishers for manual fire fight-ing.
The fire load in the area is low.
The fire protection features yl currently 'installed in the control room and the continuous manning of the control room provide adequate defense-in-depth fire fighting capability for these areas.
In addition, an alternate shutdown system is provided with control capabilities for those systems necessary to maintain safe-shutdown capability which is independent of the main control coom.
Plant Technical Specifications require continuous occupancy of the control room by the operators.
Because the operators constitute a
continuous fire watch, manual fire suppression in event of a fire would be prompt and effective and,
- thus, a fixed suppression system will not enhance the fire protection in this,area.
i".'onclusion Sased on the above evalua tne controi room orovices
- ion, the level exi sting 'i r o
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"rotection "rogr=-,.
te nni ca'1 requi rements of Sec-ion III. G.
r'ore, oe granted.
The exe."..stion snouid,:here-uil olleciion Sys-em -or Reactor Cooian:
?
mos 1
1
~emotion
<ecues n exemotion is requested from Sec=ion i::.0 -o 'ne exient it requires an o>l collection iank sized to nold tne luoe oil inventory of all four RCP motors.
6 ~ (
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~ ~
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tach unit has four reactor coolant pumps '>i.h
=~
- ',-:"-i."
which drains to a vented closed collection tank T'n
'n ne quantity of lubri-cating oil'in each pump is 265 gallons.
The caoacity of the oil collection tank is 275 gallons.
The components have been d signed so tha.
the>
are capable of withstanding a safe shutdown earthauake (SS"-).
The collection tank is arranged
~uch that if a failure of more than one RCP motor lube system occurred, the oil collection tank would overflow onto the lower containment floor.
The lubricating oil used in the RCP motors has a flash poi'nt of approximately 480'F.
There are no ignition sources at the floor level of the lower containment.
=valuation
~he RC? motor lube oil system does not comoiy -~th Sec
- "on :i'.~ -e~
~
se the oil collection tank is not sized o contain
.he entire
'.voe oi1 system inventory.
The RCP motor lube oil system is capable of withstanding he sare snu'.-
down earthquake.
The oil collection tank is provided with su.fficient.
caoacity to hold the total lube oil inventory of one eactor "oo;~n'.
pump wi:h margin and is designed so that anv over.'-
o a sare location.
we agree ~i:h :he licensee "h-: :.<<>-
--.-,.o.-.g:
~n of features is acceptable.
t
pre a
p
'P
16-
- 11. <
Conc 1 us i on N
Based on tne above evaluation, the existing RCP motor luoe oi1 col section system provides a level of safety equivalent to the technical requirements of Section ILL.0 and, therefore, the exemption should be granted.
Summarv Based on our evalua ion, 'ne foliowing exemption reoues;.'.-..
'.; o'.-';.: ":
RHR/CTS Pump Area (Fire lone 1)
Un t 1 i 2
.ransformse.
Rooms (Fire Zones 14 i 20!
Unit 1
4 2
cSW Pump Rooms (Fire Zones 29,
- 29a, 29b
- 29c,
'gd Unit 1
8 2
-" s-Hain Steam
=.nciosure (Fire Zones 34A, 348)
Jn'i' E
2 Con rol Rooms (Fire Zones
" 6 54)
Unit 1
5 2 Oi1 Collection System Circula ing '~'ater Pump HC"'s (Fire lone 296, CCV Pump Area (Fire Zone 44S)
0 6
P ~