ML20128L272
| ML20128L272 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 05/24/1985 |
| From: | Carey J DUQUESNE LIGHT CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-5-076, 2NRC-5-76, NUDOCS 8505310325 | |
| Download: ML20128L272 (14) | |
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( 12 87 $14 (412) 923-1960 Nuclear Construction Division TelecoM (412) 787-2629 Robinson Plaza. Building 2. Suite 210 Pittsburgh, PA 15205 May 24,1985 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Mr. George W. Knighton, Chief Licensing Branch 3 Of fice of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Docket No. 50-412 Fire Protection - Trip Report Responses Gentlemen:
On December 5, 1984, the NRC staf f visited the Beaver Valley Power Station Unit No. 2 to obtain infonnation to aid in the resolution of the open item concerning the use of CO2 in the cable spreading room.
As a result of the meeting, the staf f had several concerns, which were submitted to Duquesne Light Company (DLC) in their trip report dated January 30, 1985.
Attached are DLC's responses to these concerns.
If you should have any questions, please contact Mr. E. T. Ellmann at (412) 787-5141.
DUQUESNE LIGHT COMPANY By Jg/Carey g/
YtcV President ETE/wjs Attachment cc: iIt. B. K. Singh, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
SUBSCRIBED AND S RN TO BEFORE ME THIS cg/[DAYOF '/ M
, 1985.
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7 Notary Public SNillA 5. fATTORE. 50fAtf PUSLIC SHIPPinGeoer seco, etAvit C994TT B505310325 850524 uf commissa Enriets uri.16. lH5 ADOCK 0 2
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- Mr. GOOrg') W. Knighten, Chisf Fire Protection - Trip Report Responses Page 2 COMMONWEALTH OF PENNSYLVANIA )
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COUNTY OF BEAVER
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On this [
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, be fo re me, a Notary Public [n and for said Comnodealth and County, personally appeared J.
J. Carey, who being duly sworn, deposed and said that (1) he is Vice President of Ditquesne Light, (2) he is duly authorized to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to tha best of his knowledge.
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NRC TRIP REPORT DECEMBER 5, 1984 CONCERNS 1.
NRC Concerns In our SER, we indicated that CO extinguishing systems have been installed 2
in accordance with NFPA-12.
During our site visit, we observed manual release stations and fire alarm control panels which may not be listed for use with CO extinguishing systems.
The applicant should provide verifi-2 cation that all components of the CO2 extinguishing systems are listed for use with CO2 systems.
Response
The CO systems at Beaver Valley Power Station Unit No. 2 are designed in 2
accordance with NFPA-12.
The equipment is UL listed for use in CO systems.
This list includes:
2 valves, fittings, nozzles, manual pull stations, hoses, and hose reels.
All the components of the Cardox zone panels, the interface panels and the Pyrotronics XL-3 fire detection panel are UL listed.
The design drawings have been reviewed by American Nuclear Insurers (ANI) and with minor modifi-cations have received ANI approval.
However, the panels themselves are not UL listed because the panels are custom-built to meet the more stringent requirements of the Beaver Valley Valley Power Station - Unit 2 (BVPS-2).
All modifications to the original Cardox UL-listed design have been performed by " Automatic" Sprinkler Corp (ASC0A), which is licensed by Cardox to manufacture CO2 control panels.
2.
NRC Concerns 2.A. CO does not remove heat adequately.
2
Response
CO does not extinguish a fire by heat removal.
CO extinguishes a fire by 2
2 displacing the oxygen in the area (that is removes the oxygen or acts as a I
smothering agent).
However, CO2 does have some heat removal capabilities.
Based on the NFPA handbook, CO2 removes approximately 100 Btu of heat per pound of CO -
2 The CO system is actuated by a cross-zoned smoke detection system which 2
will operate in the early stages of a fire.
Therefore, a fire will be extinguished while it is still small and has not had a chance to generate a large amount of heat.
0225-12241-B4 1
o NRC Concern 2.A.I.
Deep-seated fire, especially with cables in the vertical configura tion.
Response
CO is especially advantageous in putting out a fire in a cable tray because 2
CO total flooding basically inerts the entire area by displacing the oxygen 2
which is necessary to support combustion.
One of the major advantages of CO for this type of hazard is its capability as a gas to effectively 2
penetrate complex / congested cable tray systems, including cable trays that are installed with tops and/or bottom solid covers. All cables in trays are IEEE-383-rated cable.
IEEE-383-rated cable is self-extinguishing when the fire source is removed.
NRC Concern 2.A.2 Hot gas layer, CO2 being heavier than air and cables located near ceiling.
Response
for l
The CO system is designed to maintain a 50-percent concentration of CO2 2
a period of 20 minutes throughout the entire enclosure.
To achieve this goal, radial discharge nozzles are used.
These nozzles are specifically i
designed to entrain the air surrounding the nozzles and thoroughly mix it f
with the discharging CO.
This mixing will pull the hot gas layer into the 2
and the CO discharge, mixing the hot gases with the extremely cold CO2 2
cooler air flow from below the layer.
This mixing will greatly reduce the temperature of the hot gases, dispersing it.
I L
Fires in cables, especially IEEE-383-rated cables, generally develop as slow smolde' ring-type fires which generate considerable amounts of smoke before much heat is developed. The CO system uses reliable cross-zoned ionization 2
detectors to actuate the sytem.
Therefore, it is highly unlikely that the fire would ever develop to a size where the gas layer would reach a high temperature.
With the use of IEEE-383 cable, early detection and actuation, and the mixing ef fect of the CO2 nozzles, the development of a hot gas layer at the ceiling does not constitute a credible event.
NRC Concern 2.A.3.
If door is opened before the necessary heat is dissipated, the fire may rekindle - the pyrolites may explode.
Response
The' cable spreading area, cable tunnel, and relay room are a limited access area.
There are warning lights at each door to warn of CO discharges.
2 Therefore, only qualified personnel of the fire brigade will be opening any doors.
0225-12241-B4 2
u
Standard fire fighting practice is to test the door for heat before opening a door.
If the door is hot, a fog nozzle is applied to cool the door and provide a water curtain while opening and entering the space. This is done to prevent the escape of the fire from the space.
For an explosion to occur within a space, there has to be a mixture of oxygen and volatiles or suspended particles to provide the explosive mixture required for an explosion.
For sufficient volatiles to be generated to produce an explosive mixture, a flaming fire would have to have developed for a long period of time.
Since only a 34 percent concentration of CO is required to suppress a 2
flaming fire, it is highly unlikely that a flaming fire would continue more than two minutes after CO discharge begins and a smoldering fire would not 2
generate enough volatiles to create an explosive mixture.
IEEE-383-rated cable is self-extinguishing when the fire source, such as the 1500* flame used to test the cables, is removed.
It is unlikely that a smoldering cable fire would reignite into a flaming fire, even if all the CO was removed before the fire was extinguished.
2 NRC Concern 2.B. Toxicity
Response
Carbon dioxide ac defined in the NFPA handbook, Section 4, 15th edition is nontoxic.
However, carbon dicxide will cause asphyxiation due to the displacement of air.
In order to safeguard personnel within the areas of CO2 systems, the fol-lowing features have been incorporated into the design:
Warning signs are furnished at all entrances to CO areas to 2
inform personnel that the area is protected by an automatic CO2 suppression system.
Additionally, personnel will be trained in evacuation procedures on the release of C0.2 Flashing red lights are provided at all entrances to CO2 areas to warn personnel of the fact that 00 has been discharged into the 2
space.
Cross-zone detection / actuation lagic has been provided for the CO2 systems. The CO system upon detecting a fire will provide a fire 2
alarm warning bell in the area.
However, a second detection circuit is required before the 00 discharge cycle starts.
At 2
this time, horns will be actutted, thus warning personnel to evacuate the area. A 30-60 secoid delay (depending on the size of the area) will allow personnel to evacuate prior to actual CO2 discharges.
As an additional means of assuring that personnel are aware that 2 may be within an area, odorizers are installed in the CO CO 2
0225-12241-B4 3
system which activate on CO2 discharge. These ordorizers generate a wintergreen scent that alerts personnel to the fact that CO2 is within the area.
This feature will allow personnel ample time to evacuate the area.
NRC Concern 2.B.1.
Effects of inadvertent operation on operators.
Response
The following. design features have been incorporated to minimize the possi-bility of inadvertent operation:
The CO2 system is provided with a cross-zoned smoke detection system which, as stated earlier, requires two separate detection circuits to go into alarm before it actuates.
There are two valves, master and zone valves, which have to be opened before CO2 will discharge into a space.
The manual pull stations require two actions: pull down and then push to discharge CO.2 There is no equipment within this area for which an operator is normally required to monitor.
Seals are provided between those areas and the main control room.
Therefore, even if there is an inadvertent operation of the CO2 system, it will not affect the operators.
NRC Concern 2.B.2.
Consequences of leakage to adjacent areas through deteriorated fire stops.
Response
To prevent leakage from deteriorated seals, there are technical specifica-tions and surveillance procedures to inspect all fire barrier stops and seals on a regular basis.
However, should CO2 leak from a fire area into an ' adjacent space, the smell added to the CO2 by the odorizers will warn personnel of this fact and allow them time to evacuate the area.
'NRC Concern 2.C. Design
Response
The CO system is part of a defense in-depth philosophy of which no one part 2
is complete by itself.
This defense in-depth philosophy can best be summa-rized as three independent levels of fire defense.
They are:
1.
. Provide a low probability of a fire by:
0225-12241-B4 4
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.a.
Three-hour: - barriers separating th'e ~different fire areas.
.b.
R'estricted access'by electrically supervised security access
' locks,,--which places the - areas of concern 'out - of normal: travel routes,. and reduces ' the probability. of thefintroduction 'of -
transient combustibles.
- c.
- Low. activity. area (mostly cable and conduit' with no' large
-machinery).
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d.
All cable.is IEEE-383 qualified or run in conduit.
1 e.
Adminstrative control: procedures control access, transient-combustibles,. ignition sources, and work activities with'in' the areas.
-2.
Detection and Suppression Capability:
jj a.
Two ' separate fire detection systems. are provided to protect-the area'; one an ionization smoke detection system called.the "Early Warning System" provides alarm / warning of a fire-L throughout - the plant.
,The other is the smoke detection /-
actuation system scalled the "XL-3 system"- which provides -
local alarm and warning, and actuation of ' the CO 2 system.
b.
The~CO suppression system utilizing two complete discharges 2n at 50 percent.. concentration of CO2 and a 20-minute soak time.
c._
A well-trained fire brigade with water' from hose stations, and portable extinguishers as backup _ fire protection.
d.
- The local fire departements have been trained in response _ to_
a fire at Beaver _ Valley Power Station.
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'3.
Alternate _ Shutdown Capability.
a.
. A fire in the cable spreading area', cable tunnel, and relay room is considered to destroy:: all cables in. these ' areas; therefore, an independent ' alternate shutdown.. capability is provided which is electrically independent and not affected
.by the loss of these areas.
The'CO2 _ system is ' designed in _ accordance.with-NFPA-12. The system is fully automatic and Lisa actuated by _ a - cross-zoned smoke detection system.
The majorz design _ features' include:
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,1.
' 50 percent concentration of CO2 12.
_-Double discharge capability
=3.
Two separate storagef tanks that are independent of each other i
4.'
-A designed 20-minute soak time 0255-12241'-B4 5
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L 5.1 Automatic, manual electric, E and manual: means - of actuation are
'provided 1
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'6.
Meets C0 design criteria of BTP CMEB 9.5-1, Section C.'6.e 2
h.ocal, remote,andpredischarge' alarms-7.
CO 7 system, designed. to warn personnel' of ~ the 8.
- 0dorizers ; in-the 2
- presence
- of C02 NRC' Concern
-2~C.1.
~~The cold:CO2 impinging on cables may deteriorate the insulation.
Response
.The cablesLin the areas of the CO2 nozzles-will be protected from direct CO2 impingement by. providing shielding in the form. of cable tray covers or-bottoms as required.
-NRC Concern 2.C.2.
Consequence of' excessive pressure, if pres'sure relief panels do not work.as designed.
Response-The'CO2 system will _.be placed_ into operation only af ter all of the accep'-
tance' tests have been successfully performed. This includes full CO2 system discharge ~and observation of the integrity.of the area boundary components.
'NRC Concern i
- 2.C.3.
Effects of expected overpressure on fire seals.
s
Response
The a fire stops and. seals will. be designed to withstand the' potential CO2 overpres surization.
.NRC Concern i
2.C.4.
Consequences of multireleases'due to seismic events.
fResponse was reviewed,' with other equip-The - consequences of a. multi-release of CO2 4
ment failures, due to a seismic event in the-worst-case mode, which for CO2 is complete dischargeLof the_ entire CO2 system. The effect of multi-release was: analyzed to ensure that the plant could shut down safely.
.NRC-Concern
- 2. C'. 5 -
Conse,quenceLof electrical shorts created by an extended fire.
~
0225-122U-B4 6
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Response
In the event of an extended fire, the. alternate shutdown panel is available to shut-down the plant safely.
An analysis is being done at this time to ensure that no electrical shorts will inhibit the plant from being shut down safely.
NRC Concern 2.D.~ Availability
Response
During normal plant operation, the CO system will~ be in an automatic mode 2
of operation. This is based on the facts that:
a.
These areas are security monitored limited access areas for personnel with proper security clearance only, b.
It is not a normal travel route.
c.
Contains mainly cable and conduit with few electrical components that will require periodic monitoring.
The CO system is also technically specified so that if, for any reason, the 2
CO system is not fully operational, a fire watch will be stationed in the-2 area.
-The CO cystem is designed so that a key is required to lock out the CO2 2
system (Note:
this only disables the automatic actuation system). Locking out the system actuates alarms locally 'and in the control room, notifying the operators of the' system abnormal status.
Abort switches are provided for personnel safety.
The abort switches are designed - to interrupt the automatic = evacuations of the CO2 system, thereby extending-the evacuation time.
The abort switches are of the spring return
" dead-man" type, so that the abort switch has to be held in the abort position.
The operation of an abort switch will cause an alarm in the control room and locally.
The' abort switches are overridden by the manual-electric-pull boxes and by manual operation of the CO2 system.
Also, to. increase availability, the CO system is powered from the 125-V dc 2
system which has both black diesel and battery back-up on loss of ac power.
NRC Concern
- 2.D.1 Lack of availability becuase CO2 system is disabled during main-tenance when probability of fires is greatest.
0225-12241-B4 7
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Response
'As discussed above, it is planned that all major maintenance will be con-ducted during plant shutdowns, that the CO system is technically.specified 2
to. provide
- a. fire watch.if the CO system is disabled, that a key is re-2
. quired to lock the system out of automatic discharge, that manual actuation is - still available, and that the system will alarm locally and in the control room if the system is in the locked-out mode.
NRC Concern 2.D.2.
Number of LERs on CO2 systems found disarmed.
-Response-
- There have been no LERs written on BVPS-1 for the disarmement of the CO 2 system.
In review of past LERs, there were only a few instances where CO2 systems were reported as being disarmed.
In each case, the CO2 system was disarmed for either testing or maintenance purposes, and fire watches were posted in accordance with procedures.
NRC Concern 2.D.3 Poor record on " Acceptance Testing" of CO2 Systems.
Response
The CO2 systems will be put into operation only after acceptance tests-performed in accordance with NFPA-12 ANI acceptance testing and manufactur-ers' instructions are successfully passed.
NRC Concern 2.E. Record
-2.E.1.
Browns Ferry
, Browns Ferry fire - lessons learned (NUREG-0053).
"It -is obvious that the longer a fire burns, the more damage it will do.
The Browns Ferry fire
- shows that prompt extinguishing of a fire is in most circumstances, also the way to limit the consequences of a fire on public safety. The Review Group recommends that serious consideration be given to installing or upgrading fixed water sprinkler systems, and to make. them automatic.
This is espe-cially important in areas containing a high density of cables or other-flammable materials, where there is a combination of flammable materials and redundant safety equipment or where safety equipment is located and where j
access _ for fire fighting should be considered in the design and procedures."
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Response
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The above excerpt is from Section 1.6.2 of NUREG-0050. Section 1.6, Princi-jr pal Recommendations, states "The reader should be reminded that not every 0225-12241-B4 8
E
recommendation applies to every nuclear power plant." Additionally, it goes on to state "Other alternatives besides those recommended by the Review Group may be equally acceptable. From among the various alternatives, those appropriate and sufficient should be chosen for a given plant. For differ-ent plants,'it will quite likely be found that different choices are appro-priate and sufficient."
The, Feview Group. acknowledged - that the first line of' defense with regard to fires is. an effective fire prevention program.
It was found that Browns Ferry used a highly combustible penetration seal, an unnecessary ignition source. '(candle to test' for air leakage), and a highly combustible type of cable insulation.
These concerns do not apply for BVPS-2. All penetration seals 'use noncombustible material which have been verified to withstand the
-effects of highly intense fire.
BVPS-2 will not check fire seals with open flames.
Lastly, BVPS-2 has - utilized cable that has passed IEEE-383 flame test for vertical configurations.
j The second line of defense pertains to detecting and extinguishing fires
. promptly to limit the extent of damage.
The Review Group stated that the detectors should be designed to detect the products of combustion from the combustible material and should be properly located. For the cable spread-
'ing room, relay room and cable tunnel, BVPS-2 has removed the heat detectors that' were originally designed to actuate the fire suppression system and replaced these with smoke detectors.
This was done to reduce the response time required to detect a fire.
l It should be noted that the fire 'in the Browns Ferry cable spreading room was controlled and extinguished without the use of water.
The fire in the
- Reactor Building, which did not utilize a fixed suppression system, was fought unsuccessfully with portable carbon dioxide and dry chemical extin-guishers.
Once a hose stream was directed towards the fire, the fire was quickly extinguished.
The Review Group is concerned about the reason for using water on cable tray fires.
BVPS-2 procedures. and fire fighting training emphasized the use of water from the hose racks utilizing nozzles locked in the fog position as a means for manual fire fighting capabilities for are'as containing high concentration of cables. Adequate fire hoses will be'provided throughout the plant.
The capability for the control of the ventilation system is provided at BVPS-2 to deal with fire and smoke.
Upon receipt of a smoke alarm signal, the supply and exhaust fans to the cable spreading area / cable tunnel are shut down.
The Review Group states that provisions should be implemented to assure that l
systems that are required to safely shutdown the plant are available.
BVPS-2 has installed an Alternate Shutdown Panel (ASP) that is completely
. independent from the cable spreading room, relay room and cable tunnel.
That is, a fire in the above-listed areas will not prevent the safe shutdown
-of the plant.
0225-12241-B4 9
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NRC Concern 2.E.2.
NRC Guidelines l
Our guidelines reflect the recommendations of NUREG-0050 and summarize them in Paragraph B.2 of BTP CMEB 9.5-1, "Use of Water in Electrical Cable Fires" (page 9.5.1-4).
Response
Water in most cases provides the best means of extinguishing an electrical fire, if water can be placed direct onto the fire. The design of the BVPS-2 cable spreading room is not conducive to direct water application.
As a result of compliance with Regulatory Guide 1.75, cable tray covers and/or bottoms will be installed on approximately 60 percent of the trays for separation.
These covers and/or bottoms provides a barrier which obstructs the oirect application of water to the fire.
CO by virtue of its gaseous 2
nature will penetrate into these cable trays and provides fire suppression to the fire.
Due to the stack arrangement of the cable trays and the fact that the trays are provided with covers and/or bottoms, DLC's position is 2 system provides prompt extinguishing of the fire and ensures that the CO the safety of this area.
In addition to the fixed CO2 system, hose stations are provided as a backup for use by the onsite fire brigade and offsite local fire departments.
NRC Concern 2 E.3.
Implementation It has been NRC policy since the guidelines were issued in 1976 to require for all NOTLs to install a fixed-water suppression system in each of the cable spreading rooms.
Response
The guidelines applicable to BVPS-2 are those contained in NUREG-0080, Standard Review Plan (SRP).
In accordance with the requirements of 10CFR50.34(g)(1), BVPS-2 should be evaluated against the SRP in effect six months prior to the docket date of its application (Application docketed May 18, 1983).
10CFR50.34(g)(3) also establishes that "The SRP is not a requirement." The substitute for the regulations and compliance is not a SRP in effect six months prior to bVPS-2 docket is Branch Technical Position CMEB-9.5.1.
Section C.7.c.,
Cable Spreading states in the first paragraph that the ".... primary fire suppression in the cable spreading room should be an automatic water system.....".
However, in the second paragraph of this same section, gaseous systems are discussed along with the criteria of when they are acceptable. These BTP guidelines indicate that both water and gas are acceptable suppression systems.
The guidelines issued in 1976, Appendix A of BTP APCSB 9.5-1,
. contained specific guidance that "... gas systems may be used for primary fire sup-pression if they are backed up by an installed water spray system...".
When BTP CMEB 9.5-1 was written, the guidelines of Appendix A to APCSB 9.5-1 0225-12241-B4 10 L
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were incorporated and Appendix A was deleted.
The specific. guidance to install a backup water spray system when:using a gas suppression system was also deleted.
Appendix R of 10CFR50 is presently the only regulation which contains specific fire protection requirements.
Although Appendix R is not.applica-ble to BVPS-2, these requirements have been included in the guidelines of the BTP CMEB 9.5-1.
Appendix R does not contain any requirement relative to the unexceptability of CO2 as
- a. fire suppressant. Since 1976 at least five nuclear plants have'been licensed with a CO2 system without a fixed water suppression. system. Similarly, an additional three plants have been licensed with only a Halon system.
NRC Concern 2.E.4.
Other Guidelines Th'e International Guidelines for the Fire Protection of Nuclear Power Plant (1974) also speelfy water for cable fires.
Response
The International Guidelines for the Fire Protection of Nuclear Power Plants
-(Revised Edition, 1983) recoLmend. that deluge systems be used to. protect-areas with' extensive cable concentrations.
However, these guidelines also.
state that gaseous suppression should be considered for cable rooms where sprinkler systems are not acceptable for specific reasons.
Our insurer, America,n Nuclear Insurers (ANI), has accepted the concept of carbon dioxide in the cable spreading room based on the fact that the cable trays will have covers and/or bottoms installed.
3.
'NRC Concern In our SER, we indicated that the fire alarm system complies with 72D for a Class "A" system.
Based on observations during our visit, we raised con-cerns about the fire alarm systems compliance with NFPA 72D with regard to the -list of all equipment and circuit supervision.
The applicant should provide verification that the fire ala rm systems comply with 72D for Class "A" system.
Response
- All safety-related areas of the plant are protected by the "Early Warning" Fire Detection System.
The early warning fire detection system is a Honey-well Multiplex system, consisting of smoke detectors (ionization and photo-Lelectric) and flame detectors (ultraviolet).
This system is a Class A circuit as defined in NFPA 72D (1978) or a style D system as defined in NFPA 72D (1980). ~
For the actuation of the CO2 and Halon systems, there is a fire detection /
-actuation system which is called the "XL-3" system.
This system provides daplicate _ coverage to the Early Warning System in areas protected by CO2 or Halon.
The XL-3 detection system consists of " smart detectors," that is, 0225-12241-B4 11
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n smoke.' detectors-with computer chips in them, so they.can " talk" to the main
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process panel.. This panel is. called the XL-3 panel which provides a print-
'out' of detector status and all alarm functions.'
The: circuits between the.
- detectors, and the -XL-3 system are all - Class "A. ".- The - XL-3 panel sends a :
signal to-the-C02 or-Halon local fire panels to. actuate._a fire alarm locally.
. and 'a -second ' signal.- (the cross-zone'd part) to actuate the CO /Halon pre-2
~. discharge : alarms -and discharge cycles. All these circuits.and the actuation circuits are ' Class "A" circuits.
The CO /Halon system local panels also 2
s
- provide s'upervised - annunciation on the " Building Services 1 Control Panel"
' located:in the control room.
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0225-12241-B4 12
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