ML20072R955
| ML20072R955 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/22/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20072R945 | List: |
| References | |
| NUDOCS 8304060511 | |
| Download: ML20072R955 (12) | |
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g NUCLEAR REGULATORY COMMISSION g.-
p w AsHINGTON, D. C. 20555
(;*****j SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATI.ON' RELATED TO EXEMPTION FROM 10 CFR 50, APPENDIX R ARKANSAS POWER & LIGHT COMPANY ARKANSAS NUCLEAR ONE, UNIT NO.1 DOCKET NO. 50-313 1.0 Introduction By letter dated July 1,1982, the Arkansas Power and Light Company (the
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licensee) requested exemptions from the' technical requirements of Section III.G of Appendix R-to 10 CFR 50 for various areas in Unit 1..
By letter dated Novenber 11, 1982, the licensee provided new proposals and additional clarifying information regarding the previous exemption reques ts.
Section III.G.2 requires that one train of cables and equipment necessary to a::hieve and maintain safe shutdown be maintained free of fire damage by one of the following means:
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Separation of cables and equipment and associated non-safety circuits of redundant trains by a fire' barrier having a three-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 barrier; b.
Separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustible or fire hazards.
In addition, fire det'ectors and an automatic fire suppression system shall be installed in the fire area; or Enclosure of cable and equipment and associated non-safety circuits c.
of one redundant train in a fire barrier having a one-hour rating.
In addition, fire detectors and an automatic fire s'uppression system shall be installed in the fire area.
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 installed in the fire area of concern if it contains a large concentration of cables or other combustibles.
These alternative requirements are not deemed to be equivalent for all configurations; however, they provide equivalent protection for those configurations in which they are accepted.
Because it is not possible to predict the specific conditions 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 8304060511 830322 PDR ADOCK 05000313 F
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r)easures 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 modifica-tions will provide a level of safety equivalent to the technical require-ments of Section III.G of Appendix R.
In ' summary,Section III.G is related to fire protection features for ensuring that systems and associated circuits used to achieve and maintain safe shutdown are. free of fire damage. Fire protection configurations must either meet the specific requirements of Section III.G or an alter-
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native fire protection configuration must be justified by a fire ~ ha'zar'ds analysis.
-.e Our general criteria for accepting an alternative fire protection con-figuration are the following: '
.M The alternative assures that one train of equipment necessary to achieve hot shutdown from either the contml 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 III.G would be detrimental to overall facility safety.
2.0 " Intake ' Structure 2.1.1 Discussion-Below El. 354' The intake structure consists of three floor levels (i.e. below El. 354',
El. 354' & El. 366').
The first level is below El. 354' and contains circulating water piping, associated valves and power cables. The power cables. for redundant pumps are separated by less than 20 ' feet. This floor level is the pump intake bay for the service water pumps and is therefore partially filled with water. The licensee proposes to reroute cables to provide greater than 20 feet of separation at this level.
Portable fire extinguishers, manual hose reels, and ionization detectors are provided throughout the area.
2.1.2 Evaluation - Below El. 354' After the proposed cable rerouting, this zone will have 20' separation and automatic detection but will not have an automatic suppression system required by Section III.G.
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. ANO-1 This zone consists of the service wa'ter purd intake bays, therefore the water level in the intake bays precludes the possible accumulation of transient combustible materials as anticipated in other plant areas.
Because the likelihood of an exposure fire is low, these alternative features compensate for the required suppression system and provide a level of fire protection equivalent to that required by Section III.G.
of Appendix R, and therefore are acceptable.
2.1.3 Conclusion Based on the above evaluation, the fire protection provided balow El. 354',
with the proposed modifications, provides a level of fire protection r
equivalent to the technical requirements of Section III.G of Appendix R, and therefore, the exemption should be granted.
- se 2.2.1 Discussion - El. 354" M
The second floor level is at E1. 354' and contains redundant cable trays and conduits for the service water pumps and discharge valves. The redundant cables at this level are in horizontal cable trays and are separated by approximately.16 feet. The in-situ cocbustible loading approximately 950 BTUs/FTging primarily of cable insulation, is at this elevation, consis
, which if totally. consumed would correspond to an equivalent fire severity of less than one minute on the ASTM E-119 standard time-temperature curve. This fire area is provided with a smoke detection system. The licensee proposes to ' reroute.all cables required for the service water pump motors to provide greater than 20 feet of separation. However, the cables for the service water pump discharge valves are separated by only 16 feet. The licensee proposes to provide a one-hour b.arrier for the conduit and trays providing power for one of the two sets of three valves constituting one complete path from the swing pump. The licensee contends that the low combustible
. loading.in this area, combined with the proposed one-hour barrier, is Mustification for the lack of ari automatic suppression system.
2.2.2 Evaluation - El. 354' This area does not comply with Section III.G because there is only 16 feet of clear separation between redundant trains of cables for the discharge valves and an automatic suppression system is not provided.
Redundant cables for the service water discharge valves are located approximately 10 feet above the floor level.
Because of the low in-situ fire load, separation between cables, large room volumes, and detection system, there is reasonable assurance that one train of service water pumps will be maintained free of fire damage in the time interval required for fire brigade response to extinguish a fi re.
These alternative features compensate for the protective features required by Section III.G and provide an equivalent level of fire protection and are, therefore, acceptable.
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2.2.3 Concl usion The level of existing protection in this area in conjunctios witti the proposed rerouting of cables and one-hour barriers provides a level of fire protection equivalent to Section III.G of Appendix R; therefore, the exemption should be granted.
2.3.1 Discussion - El. 366' The uppermost level of the intake structur is at El. 366', and contains the A and 8 trains and swing service water pump' motors, valves and cables. The diesel driven fire pumps and day tanks are also located at this elevation but.are separated from the rest of the area by three-hour rated fire barriers..
The A-train service water pump is' separated from the B-train pump by 24 feet horizontally. The B-train pump is reparated from the swing pump by 29 feet horizontally.
partial-width missile barriers are provided to further separate the three pumps. 'ihe pump motors are situated several feet below the ceiling.
In our opinion, the hot gas layer will not extend to this level.
Each pump motor contains six gallons of lubricating oil. Floor drains are installed in the vicinity of each purp to collect and drain any potential lube oil leaks.
Redundant discharge valves are separated by approximately five feet, on opposite sides of the previously mentioned missile barriers.
2.3.2 Evaluation - E1. 36G' This zone.does not have 20 feet of separation free of intervening combustibles between redundant trains or an automatic suppression system as required by Section III.G. Because of the low in-situ fire load, large room volumes and the partial width missile barriers installed.between each pump, and. the ceiling height above the pumps, there is reasonable assurance that one train of service water pumps will be maintained free of fire damage in the previously discussed time interval required for fire brigade response to extinguish an exposure fi re. Although the pump discharge valves are separated by approximately five feet, they are effectively shiel'ded from an exposure fire by the intervening missile barrier. These alternative features compensate for the automatic suppression system required by Section III.G'and provide an equivalent level of fire protection, and are therefore acceptable.
2.3.3 Concl usion Based on the above evaluation, the existing fire protection for El. 366' provides a level of fire protection equivalent to the technical require-ments of Section III.G of Appendix R, and therefore the exemption should be granted.
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3.0 Yard Area Manholes (IMH04 and 1MH06) 3.1 Discussion This fire area consists of two manholes which are concrete bunkers approximately 5 feet by 5 feet by 5 feet, and are located remote from the remainder of the plant. The power cables for redundant trains of service water pumps are located in close proximity inside the manholes.
The manholes am not ventilated and can be accessed only by lifting the concrete hatches with a crane. The licensee proposes to fill the manholes with a non-combustible material such as sand or vermiculite.
3.2 Eval uation The redundant service water pump cables in the manholes are neither separated by 20 feet nor enclosed in one-hour fire barriers. Smoke detection, automatic suppression, and alternate shutdown capability are not provided.
Filling the manholes with sand or vermiculite will prevent a fire from occurring in the manholes and, therefore, an adequate level of fire protection has been provided.
3.3 Concl us ion The level of protection for the yard area manholes provides a level of fire protection equivalent to Section III.G of Appendix R.
Therefore,
the exemption should be, granted.
4.0 Radwaste Processing Area - (Fire Zone 20Y)
This fire area includes two sub-areas which contain redundant trains of safe-shutdov.n equipment (i.e. waste monitor tank room and the make-up pump rooms and adjacent corridor).
4.1.1 Discussion - Waste Monitor Tank Room The treated waste monitor tank room contains both borated water storage tank (BWST) dropline valves and associated cables. The room is of reinforced concrete construction and is approximately 37 feet by 34 feet with a 17-foot ceiling. There are no in-situ combustibles in this room.
The redundant BWST valves are located near-the ceiling level and am separated by approximately four feet.
Ionization detectors, portable fire' extinguishers and manual hose stations are available throughout the entire fire area. The licensee
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proposes to install a one-hour rated fire barrier to protect one train of conduits associated with the BWST valves and to install a partial coverage sprinkler system for the valve area.
4.1.2 Evaluation - Waste Tank Monitor Room This zone has automatic fire detection, separation of redundant conduits by a oce-hour fire barrier, and an automatic suppression system in part of the area.
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Because thes e are no in-situ combustibles in this room, an exposure fire would involve transient combustibles, ' Due to the limited personnel access to this area for health physics reasons it is unlikely that a large quantity of transient combustible materials could accumulate.
Therefore, any potential fires in this area would b'e of limited severity and duration. Due to the considerable heat sink provided by the concrete floor, walls, and steel tanks in the area, there is slight possibility that a fire could damage both redundant BWST valves before actuation of the' detection,and automatic suppression systems. A one-tour rated barrier between redundant conduits will provide agadded margin of safety against premature fire damage.
2 Based on our evaluation; we conclude that the alternative protect @ig features pmvided for the BWST dropline valves provide a level o i re protection equivalent to Section III.G of Appendix R and therefore are acceptable.
g 4.1.3 Conclusion - Waste Monitor Tank Room The level of existing protection for thic area in conjunction with the proposed one-hour barrier and automatic suppression system provides a level of fire protection equivalent to Section III.G of Appendix R.
Therefore, the exemption should be granted.
4.2.1 Discussion - Make-Up Pump Rooms and Adjacent Corridor This section of the fir'e area is L-shaped and consists of a corridor a'nd the make-up pump cubicles at the end of the corridor. The make-up pumps are in three adjacent cubicles approximately 10 feet by 20 feet. The pumps are separated by less than 20 feet.
Physical separation between the pumps is provided by 8-foot, ' partial height walls.
The ceiling height in this fire area is 17 feet. One of the three pumps must be maintained free of fire damage to safely shut down the plant.
Each make-up-pump contains 10 gallons of lubricating oil.
Redundant cables for the pumps are muted in conduit. The cables are routed from the pumps to the ceiling level in the pump cubicles.
Frem there the cables for the A and C train pumps are routed into the adjacent corridor, and remain at the ceiling level for the length of the corridor. The licensee proposes to reroute cabling associated with the A make-up pump suction valve to provide greater than 20' separation. Additionally, one-hour barriers will be provided for the trays and conduits associated'with power for the pump and suction valve of the swing and one other pump within each individual pump room.. Portable fire extinguishers, manual hose stations and a smoke detection system are provided in the area.
4.2.2 Evaluation The licensee proposes to reroute the A train cables in the corridor area.
Therefore, only the redundant cables and equipment in the make-up pump cubicles need to be protected in order to comply with Section III.G.
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the make-up pump cubicles, the licensee has not provided an automatic l
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Access to these areas is restricted for health physics reasons, and partial height walls are provided between the pumps.
It is our opinion that these features, in conjunction with the proposed one-hour barriers, will mitigate the onset of cable damage for a sufficient time-period to enable the fire brigade to respond and extinguish a fire. prior to damage of both trains.
4.2.3 Concl usion The level of existing protection for the make-up pump rooms and the adjacent corridor, combined with ahe proposed modifications, provides a level of fire protection equivalent to.Section III.G of Appendix R; therefore, the exemption should be granted.
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5.0 Containment Building (Fim Areas 32K and 33K) 5.1 Discussion For the purpose of analysis, the licensee has subdivided the containment building into two fire areas. There is no fim barrier between the two fire areas.
The separation of cables and e_quipment within each fire area is such that only one divis~ ion of equipment is located in each fire area.
The minimum separation distance between all redundant equipment in the two fire amas considering intervening combustibles is less than 20 feet.
Intervening combustibles in-the fom of non-safety related cable trays provide a potential path for the sp' read of flame from one fire area to the other. Fire stops have been installed in the cable trays to prevent the spread of flames along the cables from one fire area to the other.
Both fire areas are protected by a partial coverage smoke detection system.
flanual hose stations and an oil collection system for the reactor coolant pumps are also provided.
The fire area in the north half of the containment building cont'ains two decay heat drop line (RHR letdown) valves, in series. A spurious operation of both valves could cause breach of primary system integrity.
This action could take place if a short, phase to-phase in a specific manner involving the power cables to the valves, would occur.
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are routed in close proximity in this area.
5.2 Evaluation Inside non-inerted containment,Section III.G mquires the separation of cables and equipment and associated non-safety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening p
combustibles or fire hazards.
Cables and equipment are physically separated by more than 20 feet, however, inside containment, non-safety related cable trays pass between the two fire areas and provide a potential path for flame spread between mdundant divisions.
The installed fire stops in these non-safety related cable trays should prevent the spmad of flames along the cables.
Due to the restricted access to this area, the probability of an exposure fire from the accumulation of transient combustibles which could potentially bypass the cable tray fire stops is low. The fire stops ' installed in the intervening cable trays l
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y pmvide reasonable assurance' that although redundant trains are not separated by the required distance free of inter'vening combustibles,
, one train will be maintained free of fire damage.
Because the amount of in-situ combustibles is low in this area and early warning detection is provided, the pmbability of a fire which could damage both RHR valve conduits is low. We believe that the pmbability.that this damage would occur in such a specific manner is low. This combination of conditions provides reasonable assurance that a spurious operation of both valves in the RHR system is not likely to occur.
5.3 Conclusion Based on.the above evaluation, we conclude that the existing level of protection inside containment provides a level of fire protecticn equival,ent to the technical requirements of Section III.G of Appendix R.
Therefore the exemption should be granted.
6.0 Pipe Area - (Fire Zone 34Y) 6.1 Discussion This fire area is a passageway bounded by reinforced concrete walls.
The ceiling height is 17 feet for a portion of the area and 11 feet for the remainder of the area. The redundant cables for the A, B, and swing service water pumps are routed within seven inches near the ll-foot ceiling level.
Redundant power cables for the decay heat pumps are also routed through this area. These cables are routed vertically and are separated from each other and from the other horizontal cables by greater than 20 feet. All cables in the area are routed inside of conduits. There are no significant in-situ combustibles in the area. Only one service water pump and one decay heat pump arp needed for shutdown.
Smoke detectors and portable fire extinguishers are pmvided in the area. The licensee proposes to enclose the cables needed for two service water pumps in one-hour rated fire barriers.
The. licensee proposes no additional protecticn for the decay heat pump cables because of their separation.
6.2 Evaluation For a configuration similar to this fire area,Section III.G requires that a one-hour rated fire barrier be provided in combination with a detection and an automatic suppression system. The licensee proposes to install the required one-hour barrier but contends that the limited fire hazard in this area does not warrant automatic suppression.
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y The in-situ combustible loading in this fire area is negligible, therefore, any postulated fire would involve transient combustible materials. Such a fire would most likely be of limited severity in a corridor area where little maintenance activities are performed.
The installed early warning detection system in conjunction with the proposed one-hour fire barrier for the protection of two service water pump cables, and the separation of the decay heat pump cables provides reasonable assurance that one train of components needed for safe shutdown.~will be maintained free of fire damage.
6.3 Conclusion Based on the above evaluation, we conclude that the level of protection
. in this area provides a level of fire protection equivalent to Section III.G of Appendix R.
Therefore, the exemption should be granted.
7.0 Pipe Area - (Fire Zone 40Y) 7.1 Discussion This area is a narrow passageway approximately 1,2 feet by 90 feet with a 12-foot ceiling. The floor, walls, and ceiling assemblies are reinforced concrete. The redundant cables for the A, B, and swing service water
- pumps are routed in conduit in close proximity at the ceiling level.
There are no in-situ combustibles in the fire area. Only one service water pump is needed for shutdown. Access to this fire area is restricted and can be gained only via a locked steel hatchway and a vertical ladder.
Smoke detection and portable fire extinguishers are provided.in th~e area.
Manual hose stations are available in adjacent areas. The licensee proposes to enclose the power cables for each of two service water pumps in a one-hour rated fire barrier.
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7.2 Eval uation For the configuration of redundant cables in this area.Section III.G requires that a one-hour rated fire barrie'r be provided in combination with a detection and automatic suppression system. The. licensee proposes to install the mquired one-hour barrier but not the required automatic suppression system.
Because there are no in-situ combustibles in this area, any. postulated fire would involve transient combustible materials. Restricted access to this area via a vertical ladder makes the probability of a sign.ificant i
quantity of combustible transient materials accumulating low. A fire in t
l this area would therefore be of lineited severity and duration.
The installed early warning detection system would be able to promptly detect incipient fire conditions, and the pmposed one-hour barrier will maintain the integrity of the cables until the fire. brigade is able to respond and extinguish the fire. Although access to this area is restricted, the fire brigade should be capable of reaching this area within a few minutes after an alarn is received in the control room.
It is our
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- opinion tha.t this combination of alternative protective features provide reasonable assurance that one train of equipment necessary for, safe shutdown will be maintained free of fire damage.
7.3 Conclusion Based on the above evaluation, we conclude that the level of existing protection for this pipe area, in conjunction with the proposed one-
. hour barrier, will provide a' lev'el of fire protection equivalent to the technical requirengots of Section III.G of Appendix R and therefore the exemption should be ' granted.
8.0 Corridor, El. 372' (Fire Zone 98 8.1 Discussion This fire area includes a corri ich is approximately 100 feet by 9 feet with a 12-foot ceiling. The floors, walls, and ceiling assetnblies are three-hour rated reinforced concrete construction. The
. corridor contains primarily B-train cables, however there is one A-train conduit in the corridor. The cables are primarily in open cable trays' at the ceiling level.
The ffre area also includes two adjoining D.C. equipment rooms which contain cables and electrical panels associated with the A-train instrumentation. This room is separated from the corridor by a three-hour rated wall, however, there are ventilation openi,ngs and an open doomay through the corridor wall to the D.C. equipment room that do not provide equivalent protection. By letter dated flovember 11, 1982, the licensee proposed to enclose the single' A-train conduit in the corridor in a one-hour rated barrier., The combustible loading in. the corridor consists of a large amount of B-train cables in open cable trays. The licensee has not quantified the combustible loading in the area.. All cables,
~ have been qualified to flame test similar to those of IEEE-Standard 383.
The corridor area also provides access to the diesel generator' rooms.
It is therefore possible that tresient conbustibles in the corridor could include 55 gallon drums of lubricating oil during maintenance periods. ~ The corridor area.is provided with an ionization type early warning ~ smoke detection system, line-type heat detectors in each cable tray, an open head water spray system that can'be automatically or manually activated, portable extinguishers, and manual hose stations. The licensee proposes to separate the D.C. equipment room from the corridor by three-hour barriers.
8.2 Evaluation liith the proposed enclosure of the corridor A-train conduits in a one-hour rated fire barrier, and the separation of the~ D.C. equipment room from the corridor by three-hour rated fire barriers, the area will comply with Section III.G.
An_ exemption is therefore not needed.
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-II-8.3 Conclusion The level of protection provided for the corridor area and D.C. equipment room meetsSection III.G; therefore, an exemption is not needed.
9.0 Lower florth Piping Penetration Area (Fire Zone 53Y)
Yard Area !!anholes (ll1H09 and ll1H10) 9.1 Discussion The licensee has 'provided alternate shutdown capability for the following areas in limit 1:
2 Lower florth Piping Penetration Area (Fire Zone 53Y) a b
!!anholes l!t109 and lith 98 The conbustible loading in'these zones is neglicible. The redundant equipment in these aPL'fD.is primarily one system, the diesel fuel transfer pumps.
The licensee reque5ts an exemption from providing fixed extinguishing and detection systens in these areas.
9.2 Evaluation These areas do not comply with Section Iil.G.3 of Appendix R to the extent that it requires fixed suppression and detection systems in these treas.
All of the fire zones for which exemptions have been requested represent a similar configuration, i.e., conbustible loading is light, there is alternate shutdown capability, and manual fire suppression equipment is available.
The low combustible loading in these areas ensures that safety related equipment in adjacent areas will not be threatened. The installation of a fixed fire suppression system will~ not significantly increase the level of fire p,rotecti.on. in these areas.
9.3 Conclusion Based on our evaluation, we find that the existing fire protection in conjunction with alternate shutdown capability in the areas for which an exemption has been requested provides a level of fire protection equivalent to the technical requirements of Section III.G.3 of Appendix R 'and, there. fore, the exemptions should be granted.
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Summary - Unit 1 Exemptions Requested 2.1 Intake Structure, below E1. 354'.- granted 2.2 Intake Structure, El. 354' - granted 2.3 Intake Structure, E1. 360' - granted 3.0 Yard Area Manholes (It1H04 an'd IMH06) - granted
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4.1 Radwaste Processing Area, Haste Mon'itor Tank Room - granted 4.2 liake-up Pumps and Adjacent Corridor - granted 5.0 Containment Building - granted 6.0 Pipe Area - Fire Zone 34Y - granted 7.0 Pipe Area - Fire Zone 40Y - granted 8.0 Corridor El. 372' - Fire Zone'98J - not needed 9.0 Lower Yard Piping Penetration Area (Fire Zone 53Y) and Yard Area fianholes (lMH09 and IMH10) - granted.
Dated: March _ 22,1983 Principal Contributors:
R. Eberly, G. Vissing, O. D. T. Lynch, Jr.
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