ML19329C720
| ML19329C720 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 12/27/1977 |
| From: | Engle L Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8002180213 | |
| Download: ML19329C720 (13) | |
Text
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II DEC 2 71977 U wVA T @' l fy- ] ippI f
Docket No. 50-346 d be i;& Jbd h a i
APPLICANT: Toledo Edison Company FACILITY:
Davis-Besse, Unit 1
SUBJECT:
SUfEARY OF MEETIfiG HELD Oil DECEMSER 6,1977 WITH THE TOLEDO EDISON C0t*PANY REGARDING FIRE PROTECTION IN THE FACILITY CABLE SPREADING ROOM - DAVIS BESSE,
- T 1 A meeting was held on December 6,1977, with tne Toledo Edison Cccoany and the NRC staff regarding the fire protection capabilities for the cable spreading rocm for Davis Besse, Unit 1 (DB-1). An attendance list is provided in Enclos1re 1.
SUMMARY
The Toledo Edison Cc:rpany (TECO) presented tne fire crotection design characteristics of the DB-1 cable spreading rnom which utili:es a defense-in-depth philosphy. TECO stated that P cabic screading room design and attendant administrative control prov.de assurance that, (1) the causes of electrically originated fires within the cable spreading rocm are virtually eliminated, (2) confine damage caused by electrically originated fires within the cable spreading room to a single channel Class IE or non Class IE raceway and (3) preclude the causes of non-electrically originated fires in the roon itself. provides a detail sumary of the caole spreading roca design and administrative control procedures as presented be TECO.
TECO stated that the measures taken with regard to the design of the cable spreading room precludes the existence of an electrical originated fire in the cable spreading ronm. Also, if such fires are postulated to exist, these fires will be contained within the raceway which encloses the faulted circuit.
TECO stated that administrative procedures virtually eliminated the threat of an exposure firein the cable spreading room. The administrative proceddrest include: (11 the control of access by way of locked doors with alarms to the control room and gate house and the accompanying of the fire narshall of his designated alternative, (2) the strict control of ignition devices and combustibles, and (3) the prohibition of combustible storage.
U The NRC staff stated that they were most anxicus to obtain copies
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of the slides presented at the meeting which showed the fire tests which have been conducted by TECO. TECO later stated that the slides me mil me thm Am tmil e nf ths fien tae+e iw 1 A ha nmwidad me an ap endix to theltr forthcomiAg amended Fire'liazard Analysis Report for
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l Also, the NRC staff stated to TECO that they were presently evaluating l
the possibility of an exposure fire in the cable spreading room and would advise TECO on the staff's conclusions after further staff evaluation of the forthcoming amended Fire Hazard Analysis Report for DB-l.
Origi:ml ::1,msd t/
Lecc 3. E.r.;10 Leon 8. Engle, Project Manager Light Water Reactor Branch No.1 Division of Project Management
Enclosure:
1.
Attendance list 2.
Fire Protection Design Evaluation ec: See next page ha f' f I3). _ - u L bwi :
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NRCFORM 318 (9 76) NRCM 0240 W u. a. oovensemem? Panarine opricsa sere-ese.eae
i Toledo Edison Company ATTN: Mr. Lowell E. Roe i
Vice President - Facilities Development Edison Plaza 300 Madison Avenue Toledo, Ohio 43652 l
Donald H. Hauser, Eso.
The Clevelan<t Electric Illuainating Company P. O. Box 5000 Cleveland, Ohio 44101 i
Gerald Charnoff, Esq.
Shaw, Pittnan, Potts & Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 Lesslie Henry, Esq.
i Filler, Seney, Henry & Hodge 300 Madison Avenue Toledo, Ohio 43504 4
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NRC PORM sis (9 74) NRCM 0240 W u. e. eovsamme=7 emenvine orricas e en - eawas
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s ENCLOSURE 1 MEETING ON DECEMBER 6, 1977 THE TOL000 EDISON COMPANY DAVIS BESSE, UNIT 1 50-346 NRC L. Engle G. Harrison V. Leung
'/. Matthews
- 0. Notley A. Szukewic:
TEC Calcamuggio W. Mitchell M&M Protection Consultants J. Robinson R. Weiss Bechtel Corporation P. Anas S. Carter R. Jackson R. Madden R. Manney C. Miller E. Ray G. Stashik
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E!!CL05tlRL 2 FIRE PROTECTICf1 DESIGil 0F THE CABLE SrREADItG ROOM FOR DAVIS GESSE, U!1IT 1
_Ef!VELOPE OF ROOM The free volume of the Cable Spreading Rocm is approximately 60,000 cubic feet.
The envelope of the room is composed of walls, ficors, ceilings, penetration seals, and access doors all of which carry fire ratings.
Floors, walls, and ceilings are all fire resistant concrete or 12 inch masonry concrete bicck carrying 3 bcur ratings.
Both main access doors are also 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated, in addition, the 2'3" x 2'8" elevator access door is also rated 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
The 2-1/2' x 2-1/2' ficor access hatch is a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated door although it does not carry a full rating vehen oriented in the horizontal position.
In order to maintain the fire rating integrity " hen openings for mechanical or electrical functions (ducts, cable trays, conduit, etc.)
must breach a wall, ceiling, or floor, penetrating seals were cmcicyed.
These seals are composed of silicone foam material which was pr, viced and installed by BISCO. Inc., of Elk Grove, Illinois.
The foam material which is also used extensively throughout the remainder of the plant as well, has been tested to attain a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire rating in accordance with AST!1 E-119.
The sealant material properties and testing were described in a report submitted to the lJucicar Regulatorv Commission on August 13, 1977.
Access to the cable spreading room is threugh a door on a landing of a stairway, called AB-1, through a hatch at the top of a sectional ladder above the stairwell door near Elevator
- o. 3 and through a door from a platform reached by a ladder in a roo,desicnated as Room 422B.
However, since there is virtually no eauipment in the rocm there is no reason for immediate access to the room itself and there-fore, entry will be strictly controlled by TECO.
The doors will always be locked with the appropriate key available only frcm the shif t foreman with the concurrence of the station fire marshall or his designated alternate.
Each entrance to the rocm is monitored by the Contact Logger. Opening of the door or h3tch initiates a change of state status alara in the Main Centrol Room via the Contact Lcgger which provides specific identification information.
The person seeking access will be accompanied by and remain with the fire marshall or his designated alternate.
This procedure will be utilized for maintenance, housekeeping or for any other acccss reasons, if any, to the Cable Spreading Room.
Administrative procedures will control the introduction and use of combustible material and ignition sources into the Cable Spreading Room. A combustible material cermit approved by the shift foreman and the station fire marshall or his designated alternate will be issued for all entry to the Cable Spreading Rocm exclusive of responses
_2 to fire alarms.
In addition, when applicable, an open flare, welding, and cutting permit will be issued by the shift foreman and maintenance engineer or maintenance foreman.
These permits will cnntain information such as who initiated th' enh",
request
.,no will enter, reasons for entry, comoustible eateri... e ignition source checklists which will be reverified upon exitia q, er j special precautions and limitations which will identify, for exwTie, placement of fire extinguishers.
Control of this type plus the fact that no storage of combustibles or ignition sources will be permitted in the Cable Spreading Room eliminates any concern for an exposure fire.
The only ducts entering or leaving the cable spre? ding room are the supply and return air ducts from the control recm air conditiening system.
These air suoply and return ducts are crovided with 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated fire dameers.;hich conform to National Fire Protection Asscciation Code 90A and carr:, an Underuriters Laboratory Lable.
The damcers close automatically and remain tigntly closed uoco tnc oneration of a fusible link at aoproximately 160 F. Therefcre, fire external to the cable spreadinj roo'n is prevented from being transmitted to tne room via the ductwork.
In addition, sensing devices (temperature saitcher,, firestarts and duct smoke detectors) are provided in the main air supply and return ducts to detect, alarm and shutdown the fans in case of fire.
This back up protection aids in preventing the ingress of firc and smoke into the cable spreading room.
In addition to automatic actuation, manual shutdown of the fans and closure of the electricaily operated isolation dampers is possible from the "ain Control Room.
CONTENTS OF ROOM Since the function of the cable screading room is to serve as a marshalling area for all circuits external to the cable spreadinc room that interface with the main control room and cabinet rccm immediately above, the significant contents of the room are cables and associated raceways (tray, wireway and conduits) as recaired.
Witn one exception, the cable spreading room does not ccntain equirrent such as switchgear, power transformers, control cabinets. rotatinc ecuiprcent, cower cable greater tnan 125 volts, or rotencial scueces of nissiles or pice whip. The only exception is a 30 OSA, 400-120/203, dry type lighting transformer with its power feed in conduit, and a associated lighting panel coard. The only instrumentation in the room are five ionization type smoke detectors and com unicatien equipment which includes two hand sets and two speakers.
The need for access to the Cable Spreading Room during plant operation is minimal.
There is very little equipment in the Cable Spreading Room requiring maintenance, and there is virtually no eauipment recoiring operation.
Access of personnel and material into the rocm is strictly controlled via administrative procedure.
The chances of fire 'n the Cable Spreading Room are, therefore, much less than chances of fire in a similar sized room which is heavily trafficked in an uncontrolled manner.
ROOM ARRANGEMENT CRITERIA AND TOLEDO EDIS0N TESTING The race ways in the Cable Spreading Room consist of trays, wireways, and conduits which are arranged according to plant secar? tion criteria, as w'l as the requirements of the main control rcom and cahi -+ r o-equ ipment locations. Significant points are two fold.
First, thu tray system utilized at DB-1 makes exclusive use of ladder type trays with solid bottoms.
Second, the choice of this type of tray rather than open bottom trays was confirmed cuite markedly in a test conducted at Anaconda on April 25, 1973.
This test, as well as others including raceway and cables commenced prior to the issuance of IEEE 333-1974. These tests reflect the ef fort to have the electrical system design to eliminate or at least minimize the occurance of an electrically originated fire at DB-1.
The results of the test at Anaconda are as 'ollows:
l.
Flame propagation and cable ignition are retarded due to the thermal barrier provided by the 1-1/4 inches of air space between the tray bottom and top of cable support rungs.
This space lso tends to trap flame retarding gases around the cable to inhibit after burn.
2.
The major part of falling and thrown ash was retained in tray due to the solid bottom configuration.
This reduces propagation of fires to lower trays.
3.
Time-to-failure of cables was improved over the manufacturer's guaranteed 5 minutes because of the thermal barricr provided by the tray system design.
Earlier tests, July 23, 1971 and January 26, 1972 (cenducted at the Okonite Company) were performed on various tray configuraticos utilizing various tray covers (solid, vented and without covers).
These tests showed a marked tendency of trays with consecuti e sections v
of covers, both vented and solid, to cause a chirney ef#ect and hence fire propagation.
It is for this reason that the indiscriminate use of tray covers has not been allowed. Where absolutely necessary for physical spearation or flame barriers as recuired by R.G.1.75, tray covers are used but only in very short sections.
The rajority of cables s:ecified fcr use at 06-1 eet or exceed the requirements of IEEE-333-1974 even though the purchasing docu ants preparea by TECO and Bechtel preceded by two years the issuance of the IEEE document.
Except for very limited quantities of cable Nith thermoplastic insulation.
all cables are insulated with a type of thermosetting insulation (ethylene-propylene rubber or cross-linked polyethylene).
The benefit of the thermosetting insulation is that there is very little tendency to soften when subjected to heat.
Thermotplastic cables are provided as part of two di7ferent vendor packages. One vendor package has provided some teflon insulated and jacketed interconnecting cable which has been assigned to its
4 cwn dedicated wireways.
It is also encased in silicone foan within these sate wireways in order to reduce the heat transfer to or from another raceway.
The second vendor package has orovided PVC insulated crble enslos(d within a thermosetting Neoprene Jacket.
This cable is cualiti.1 -
IEEE 383-1974, and is, therefore, installed with other non-Class IE cables.
/dditional testing by TECO was conducted between September 1975 and November 1976.
These tests, again, empnasize the concern for creating a non-fire propagating cable and raceway system for use at CB-1.
The September 1975 test, at Escex, was done to investicate the flame propagation characteristics of cr. Die pullina comccunds.
The following conclusions were established based on tie test:
1.
Cable pulling compounds tcsted have no adverse effects on the, f!m e propagation characteristics of the cables beina used at DC-l is no flame propagation occurred during these tests 2.
Cables installed in conduit have their non-flute orecagating characteristics greatly in roved by bein] n: alled in condui" 3.
A cable fire at the entrance to a conduit will not propagete thrcugh,
the conduit.
The tests conducted at the Essex Ccmpany during October of 1975 verified the tray separation criteria uscd at 00-1.
The following conclusions were established based on the test results.
1.
Cable and tray installations as used at 03-1 do not ortpagate fire from one essential channel to another.
2.
These tests justify the cable tray stacking as designed for CB-1 by failure to arcoagate a fire to a tray aoove, cr to trays above and adjacent The tests conducted in February 1975 cn-site at 08-1 cere dcne to determine the effect of electrical overicading cables in trays and conduits.
The observations.c e as follows:
1.
Control and instrumentaticn cables in ccnduit :ill not self ianite.
2.
An overicaded cable will not provide a source of fire to surrcunding external cable.
3.
Cables surrounding an overloaded cable will show seme damage to the cable jacket, but will not self-ignite.
Tests ccnducted in May 1976 at the Essex Company were used to determine the effects of temperature en cables in conduit when close to an external heat source.
Tests revealed the following:
1.
Instrument, control and power cables in :onduit have shown no
~ failures of loss of circuit integrity in ti e frames up to 45 0
minutes with top of conduit temperature of 700 F.
2.
As the conduit temperature is increased toward 9000r. time to failure is decreased to about 13 minutes.
3.
Swelling of cables was due to excessive heat.
The most recent test conducted by TECO was done in November 1976 at the Essex Company.
The purpose of this test was to validate the benefit of blanketing cable trays with Kaowool, manuf actured by the Babcock & Wilcox Company of 8 lb. density and I" thickness to prevent heat transfer from a cable fire to raceways (i.e., cable trays, conduit and wireways) located above. The test revealed the following:
1.
There were lower than expected temperatures on the surface of the Kaowool. This was due to the smothering ef fect nf the Kaot. col in trapping flame retardant gases from cable and thereby not allowing cable fire to propagate or become well established.
2.
Heat transfer through Vaowool uill not danage cables in raceways above.
3.
Koswool greatly reduces release of smoke to surrounding atrcsphere.
This unexpected benefit aids in manual fire fighting of cable fires by greatly improving visiblity and reducing breathing difficulties.
During the design phase of DB-1 complete adherence to the Regulatory Guide 1.75 " Physical Independence of Electric Systems" was not possible since plant design pre-dated the issuance of R.G. 1.75 as well as IEEE 384 -1974.
However, the independence principles followed in the DB-1 design are considered adequate to precluce a ccmmon failure mode for the postulated design basis event and do, in fact, represent independence principles equivalent to R.G. 1.75.
A complete discussion of the degree of conformance, as far as the entire unit is concerr:d, is presented in the FSAR for DB-1, both as a response to Qu;; tion 8.1.2 as well as in various sect ers of i
Chapater 8.
Insofar as the cable spr3 ding room, the separatico distances between redundant channels of Class IE open tray beccre somewhat marginal when ccmaared to the 3 feet vertical and i foot horizontal clear seace distance of the guide.
The scre situation exists between Class IE and non-Class IE.
It was decided, therefore, to cover all trays in the cable spreading rocn rather than run the risk of missing one or two that should be co.ered.
The covering is acheived by the use of thermal blankets made of Koawcol material.
The initial decision to use thermal blankets was based on almnst identical applications of the blankets in the steel industry.
This decision has been reinforced by the previously discussed test findings of TECO.
ELECTRICAL FIRES PR,ECLUDED FROM STARTING TECO is confident that the cabling systen has been engineered to
minimize or virtually eliminate thc causes of electrically originated fires.
Cable selection for particular circuit functions has been donc conservatively taking into account such factors as conductor grcupin1, com:uit groupin:3, seal and barrier materials, elevated as timt ampacity ratings, etc.
This precludes overheating as an utlim.e heat source producing insuletion failure and consecuential fault.
Improbable faults, themselves, including arcinu faults which reoresent the greatest threat and the n.ost likely cause of fi ! because of the arc energy concentration, will be interrupted by the upstrean circuit protecting device.
Additionally, the care taken during construction such as meggar testing af ter pull, deburring rough surfaces of race',tay, use of smoother type fittings, etc., help guarantee the integrity of the insulation and jacketing system af ter ins.tallation.
SPECIAL TESTS--
Additional testing and test results'inc!uded:
First, a series of tests st,nsored by TECC and conducted at the Franklin Institute Research Laboratories was conducted to investigate the safety-related aspects of conduit spacing.
These tests related mainly to aspects of R.G. 1.75.
Powever, a significant findinn was that ignition of heavily overloaded cable did not occur within the
~
volume of the conduit througn which it was run.
This finding reinforces the results of the Septen:ber 1975 testing mentioned previously.
Since all power cable within the Cable Screading Room is enclosed in conduits, no Cable Spreading Room fire can result from rov,cr c251e massive overloads. Power circuits are those which continuously carry more than 10 ar.os per conducter or are greatt.r than 150 volts regardless of current.
The Franklin Institute test program was conducted from December 1976 through ltrch 1977.
The summary test report, submitted to the NRC by TECO in March 30, 1977, does not discuss this finding since the testing was to provide the technical basis for electrical conduit separation rather than flame propagation.
The second speci?1 program, a water permeability test, was conducted on the type of Koawcol used at DB-1.
The test, conducted in December 1976 at the Refractories Division of Babcock and Wilcox, assures that water can be sprayed over Koawool during a fire and thereby extinguish the flame with no dif ficulty. Thus, fire fighting is cossible through the Koawool even though the Kaowool barrier will not allow cable fire to propagate or beccme well established as proven by the l'ovmeber 1976 testing at the Essex Company.
FIRE DETECTICU AND SUPPRESSION The fire and smoke detection and associated alarming are achieved as follows.
Five (5) area ionization type fire and smoke detectors are provided in the Cable Spreadina Room. These detectors alarm visuelly and audibly on a fire alarm panet located in the Main Control Rocm
. The fire alarm panel scnds intelligerca to the Contact Legger which prints out a description of the panel en which the alarm exists.
Concurrent with the printout, the Contact Lcq;er initiates a troubie alarm via the Control Room Annunciator The annuciater alerts the c;-
M r of the ressage on the Contact Logger printer.
There are three separate Contact Logger printers. One is lecctea in the control room, another is located in the gate house, and t.he third is located in the computer room and auto-starts if either of the other two are off or fail.
In addition the contact Loggcr printer in the gate house is continuously monitored by a guard il hours a day.
The primary method of fire suppression in the Cable Spreadinu r. gen is utilization of two hose lines, one from Hose Pack No. 15 and the othec from Htse Cabinet Nn. 27., roth accessible te the Cable Snreacio, Roo:n.
Hose Rack No.16 Iccated in Sta ire.2y AB-l is directly accessible to the Caole Soreading Roon by bringing the hose line throuch the Cable Spreading Room access door 423A.
Hose Cabinet No. 27 located on Elevation 603'0" in corridor :11 is accessible to the Cable Screading Rocm by introducing t"e hose line up, into, and through Cable Snreading Room access door 4235.
The backup method of suppressien is the r.ilintion of the hose line from Hose Rack No. 20 located on Elev3tico 603'0" in Stairway AB-1.
This backs up hose Rock No. 15.
In the event addit icnai hor.e lines are required, a hose line can be connect.4 to thc standpipe fire department cornccticn on Elevation ~ 'd" in Stain:3v AB-2.
This hose line, once cennected to the stand
, can be brought up the sectional ladder which is to adjacent to the.tandpipe
'n tne stair.nv and then through the cable spreading rocm floor natch is to the stanJpipe in the stairway and then throuan the cable spreading recu floor hatch into the Cable Spreading Rocm.
In addition, protable carben dioxide fire extinguishers are located adjacent to and outside the entrances to the Cable Spreiding Roo.n.
In additon, protable carbon dioxide fire extinguisners are located adjacent to and cutside the entrance to the Cable Spreading Room.
In the event that fire' condition exists in the Cable Screading Rocm.,
the ionization fire and smoke detectors will sensa this condition and alarm on a fire alarm panel located in the Main Control Reen.
Upon annuciation of the alarm in the control room, the following sequence of events tak place based on the DB-1, Fire Emergency Procedure.
1.
An operator who is also a fire brigade member is discatched to the cable spreading room.
If a fire exists, reaardless of the size, ne notifies the control recm using Ahe units cublic address system of the exact location, the intensity of the fire, type of material burnino and then procedes to shut off the ventilation in the area of the fire.
i
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Upon notificaticn to the control room that a fire exists, the fire 2.
alarm signal is sounded over the unit's public address system and the shift foreman on duty is notified of the fire.
The shift foreman determines whether the local fire department is to be 11erted and/or sumir.oned.
3.
Once the fire alarm is sourided, the location, intensity of the fire and type of material burning is announced over tFr unit's public address system.
4 The fire brigade responds to the e with appropriate fire fighting and protective equipment such as. stt Air Packs, fire coats, boots and helmets.
Smoke removal will be accomplished by use of portable fans which will exhaust into flexible hoses approximately two feet in diameter.
If the fire does not block access to door 423A, the hoses will normally be routed thrcugh this door ano descend to ground level in stairwell AB-1.
The hoses will then exist the building from an e! vergency door of the turbine building, and the exhaust will be bicwn into the atmorpnere.
If tFe fire location precludes access to door 423A, the hoses will then be routed thrcugh one of the othar room exits.
5.
The fire brigade uses either the hand portable fire extinguishers or hose streams-deployed from adjacent hose station lines to extinguish the fire as previously discussed.
f'EETING SUt"'ARY Jocket File f;RC PDR Local PDD TIC
'AR Peading L ' 21 r i l.,
E. Case P. fjo/d R. DeVounq D. V3ssallo J. Stolz K. Kniel
- 0. P)rr S. '.' a r q a L. Crocker D. Crutch'ield F.
'.,' i l l i a m s R. f'a t t son
- 4. Centon D. Muller Project anager:
Attorney, ELD E. Hviton IE ( 3 )
I4CRS (16)
L. Dreher NRC
Participants:
S. RuLenstein D. Goller G. Lear J. Hannon s.
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