ML20050B909

Fire Hazards Analysis, Phase I Rept

ML20050B909
Person / Time
Site:	Point Beach
Issue date:	03/31/1982
From:	WISCONSIN ELECTRIC POWER CO.
To:
Shared Package
ML20050B907	List: ML20050B906 ML20050B909
References
WEPFHA01-1, WEPFHA1-1, WEPFHAO1-1, NUDOCS 8204070545
Download: ML20050B909 (200)

Text

WEPFHA01-1 t

PHASE I REPORT WISCONSIN ELECTRIC POWER COMPANY FIRE HAZARDS ANALYS71 FOR POINT BEACH NUCLEAR PLANT UNITS 1 AND 2 O .

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Neither Engineering Planning & Management, Inc. nor any person acting on its behalf makes any warranty or representation, ex-press or implied,' including the warranties of fitness for a particular purpose or mer-chantability, with respect to the accuracy, completeness, or usefulness of the informa--

tion contained in this report, or 'hnt the use of any information, apparatus, method, or process disclosed in this report ' may

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) TABLE OF CONTENTS Section Title Page

1.0 INTRODUCTION

1-1 1.1 Purpose 1-1 1.2 Scope 1-1 13 Executive Summary 1-2 2.0 CIRCUIT SEPARATIONS ANALYSIS AND REVIEW 2-1 2.1 Introduction 2-1 2.2 Method of Analysis 2-1

-23 Assumptions Used in Safe Shutdown Analysis 2-3 2.4 De finitions 2-4 25 Sa fe Shutdown Model 2-5 2.6 Results of Tasks 1 and 2 2-6 30 ANALYTICAL METHODS 3-1 31 Background 3-1 f- 32 Active and Passive Measures 3-1

(_)s 33 Passive Protection An al ysis 3-2 34 Heat Transfer 3-3' 35 Heat Flux 3-4 36 Fire Modeling 3-5 37 Radiation 3-7 38 Turbulent Buoyant Plumes and the Horizontal Jet 3-9 39 The Combustion Process 3-9 3 10 Damage Criterion 3-10 3 11 Thermal Shields 3-13 3 12 Summary of Fire Modeling Process 3-16

[ 4.0 ANALYSIS SECTION 4-1 1

4.1 EVALUATION AND ANALYSIS 4-2 4.2 Fire Zone 1: Unit 1 Motor Control Center Room 4-12 l 43 Fire Zone 2: Sa fety Injection and Con-tainment Spray Pump Room 4-24 4.4 Fire Zone 3: Component Cooling water Pump Room 4-38 1

4.5 Fire Zone 4: Unit 2 Motor Control Center Room 4-53 l

c. 4.6 Fire Area 5: Auxiliary Feedwater Pump t) Room 4-64 47 Fire Area 6: 4160V Switchgear Room 4-91 4.8 Fire Zone 7: Containment Spray Additive 4-107

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Fire Protection for Hydrogen Hazard 4-120  !

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APPENDICES t

Appendix A: Basis for Heat Release Rates A-1  :

. i Appendix B: Stra ti fication B-1 {

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Appendix C: Diffusion Plumes C-1 ,

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Appendix D: Cable Failure Criteria D-1 l j i Appendix E: Radiation E-1 -!

Appendix F: Thermal Shields F-1  :

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O 1. INTRODUCTION 1.1 Purpose This report documents the initial results of a review of fire protection features at Point Beach Nuclear Power Plant Units 1 and 2. The primary objective of this review is to identify those plant areas which comply with the detailed requirements of Section III G.2, 10CFR50 Appendix R. Secondly, for those areas addressed during this review for which specific compliance with Appendix R is adjudged to not enhance fire protection safety, a detailed fire hazards analysis is presented in support of alter-native measures which provide equivalent protection of the public health and safety. The focus of this analysis is to demonstrate O that additional mudifications implemented to achieve verbatim complianc e with Appendix R will not enhance the fire protection of the facility. ,

This report which documents the first phase of a two-phase e f fort reviewing fire protection of Point Beach Nuclear Power Plan t Units 1 and 2, analyzes the passive fire protectiori l a f ford ed by cable tray and conduit separation for sa fe (hot) shutdown systems. The second phase will address fire protection j of associated circuits of concern, cold shutdown capability and the unique fire protection features in the cable spreading room and the control room.

() 1.2 Scope t

This section provides a summary o f the investigation, ana-

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1. Introduction Page 1-2 Di

%.J lysis, and findings of Phase I of the Appendix R review. Section 2 describes the Point Beach Nuclear Plant safe shutdown systems in regards to the separation criteria provided in Section III.G.2 of Appendix R. Section 3 describes the analytical methods used to demonstrate equivalent protection to the public health and sa fe ty to th'at provided by Appendix R for those con fig ura tion s not in complete compliance with the detail ed requirements of Section III.G.2. Fin all y , Section 4 presents the results of detailed analysis and offers a substantive basis fo r ex em ption from the specific requirements of Section III.G.2 of Appendix R.

1 3 Executive Summary

() This report describes the in-depth analysis of fire protec-tion features at Point Beach Nuclear Power Plant Units 1 and 2, confirming their ability to achieve and maintain safe shutdown conditions in spite of an exposure fire involving liquid hydro-J carbons. The approach taken in this analysis involves the fol-lowing steps:

Step 1 - Identify systems and components necessary to achieve and maintain safe shutdown conditions and their location within the plant.

j Step 2 - Identify those plant areas containing sa fe shut-down equipment which do not com pl y with the detailed requirements of Section III.G.2 of Appen-dix R.

Step 3 - Per form a fire hazards analysis o f the areas iden-l ti fied in Step 2 to determine the minimum quantity l of flammable liquid necessary to damage redundant sa fe shutdown systems.

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I The identification and location of necessary plant systems involves a detailed physical inspection of each fire zone which

1. In trod uc tion Page 1-3 O

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includes the presence of intervening combustible material. This review has identified seven (7) fire zones which fail to meet the separation criteria provided in Section III.G.2 of Appendix R.

These zones are analyzed for the purpose of identifying proposed modifications which either meet the separation criteria of a one hour ASTM-rat'ed fire barrier or provide protection equivalent to the horizontal separation specified in Section III.G.2 of Appen-dix R. With the ' proposed modifications, it is adjudged that the fire zones analyzed provide sufficient protection such that addi-tional modifications will not enhance overall fire protection and that exemptions to 10CFR50 Appendix R should be granted in ac-cordance with provisions of 10CFR50.48c(6) and 10CFR50.12.

() Generic Letter 81-12 to all power Reactor Licensees request-ed information regarding specific design details of the alternate shutdown system and noted :

If you made no modifications that were required to provide alternative safe shutdown capability and if your reassess-ment concludes that alternative safe shutdown capability in accordance with the provisions of Section III.G.3 is not necessary, you do not have to provide the in formation requested by these Enclosures.

Given that an alternative shutdown system for Point Beach Nuclear Plan t is not required or proposed, a response to the enclosures of Generic Letter 81-12 is not provided.

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(~/h N- 2. CIRCUIT SEPARATION ANALYSIS AND REVIEW .

2.1 Introduction The Point Beach Nuclear Plant has been previously reviewed for fire protection adequacy in accordance with BTP APCSB 9 5-1 Appendix A. As a result of this previous review and subsequent discussions with the NRC Staff, various commitments were made by Wisconsin Electric Power Company to upgrade the fire protection at the facility. By November 1960 when the Commission promul-gated Appendix R only five open items remained from the original fire protection safety evaluation review. This report responds to three of the open items for the fire zones in question: 1) cable separation, 2) hot shutdosm capability, .t nd 3) fir e

() protection against a postulated hydrogen hazard.

2.2 Method of Analysis The method of analysis utilized to gather the data contained in this report was as follows :

Task 1 A list of equipment necessary for safe (hot) shutdown was derived from the FSAR and previous fir e hazards an al yse s . Cables and conduit directly associated with this equipment were identified using drawings and cable lists. From the hot shutdown cable and conduit list, i

plant drawings were color-coded to show approximate L /~

(_j% locations of pertinent cable trays and conduit.

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2. Circuit Separation Ana1ysis and Rev ie w Page 2-2 O'

Task-d -

A physical inspection was made of each area and zone to con firm actual locations of redundant cables ar.d con-Nuit and record dimensional data of the horizontal and vertical position of redundant hot shutdown cables and conduit. Detailed descriptions of each area and zone were docum and photographs were taken. From the dimensional data and detailed descriptions, a sketch was drawn for each area and zone which included i

required redundant division cable trays and conduit horizontally separated by less than 20 feet. The sketches were drawn to separate Unit 1 from Unit 2 and-Division A from Division B.

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Task 3 Using the sketches developed in Task 2 worst case transient combustible fires were postulated in each zone. As explained in Section 4.1, acetone was used as the fl amm ab' liquid of concern as it is the most credible, volatile, liquid hydrocarbon present at Point Beach Nuclear Plant. A series of computer models were 1

then used to determine the worst case acetone exposure fire that could cause failure of redundant divisions.

The output data hrom this analysis was used to provide c

- the basis for recommended modifications in each zone.

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Subsequent to the development of zone modifications the

'- models were again used to determine the mini .

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2. Circuit Seg.aration Analysis and Review / Page 2-3 l

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() mum vol!ume of acetone which could cause fail ure . This fi ' s ,

iterative process was continued until the" limiting ex po sur e' '

fir e condition was that assdciated with

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ceiling stratification of hot' combustion gases. Once -

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t hi's point was reached further modi,ficatio.n was not considered as additional horizontal separation would not provide any ' additional pro te.c tio n'. The fir e

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modeling considerations of Task 3 are / discussed further in Section 3 and the Appendices. -

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23 Assumptions Used In Safe Shutdown Analysis The following are the assumptions and design bases for the

() Point Beach Nuclear Plant. S9 0e Shutdown analysis:

l 1. The onl y conse,quenc'e of fire that is considered unac-i i ceptable is the, inability to safely achieve and main-tain safe shutdown conditions.

2. For the purpose of analysis, it is assumed that:

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a. The reactor is operating at 100 percent power when o ,

a fire occurs.

b. Onl y onsite emergency power is available in achieving sa fe shutdown,.

c. There is a manual or automatic scram at the direc-tion of the. Shift Supervisor to bring the reactor to hot shutdown.

3 No single or concurrent failures other than those di-l() rectly attributable to the fire are considered.

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2. Circuit Separation Analysis and Review Page 2-4

() 4. Loss of a cable does not automatically imply loss of function for the components connected to that cable.

Rather, each cable is evaluated to determine whether it is essential to the function of the compenents to which it is connected before it is concluded that the compon-ent is lost.

2.4 Definitions

1. Fire area -- an area completely enclosed by ASTM-rated barriers.

2. Fire zone -- a subdivision of a fire area defined fo r convenience o f analysis.

3 Twenty (20) foot separation -- as defined in Section

() III.G of Appendix R to 10CFR50, the. horizontal distance by which cables, equipment and associated non-safety circuits of redundant trains are required to be sepa-rated (with no intervening combustible or fire hazards and with fire detectors and an automatic fire suppres-sion system installed in the fire area) if:

a. The cables and equipment and associated non-safety circuits of redundant trains are not separated by a fire barrier having a 3-hour rating; or

b. The cables and equipment and associated non-safety circuits of one redundant train are not enclosed in a fire barrier having a 1-hour rating ( with) fir e detectors and an automatic fire suppression system installed in the fire area.

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2. Circuit Separation Analysis and Review Page 2-5

/~T 25 Safe Shutdown Model With the aforementioned assumptions and definitions in view, the following four primary safe shutdown functions must be main-tained in order to safely shutdown Point Beach Units 1 and 2:

1. Negative reactivity insertion -- maintains the reactor

! in a suberitical condition with at least 1% /1 k/k margin.

2. Pressurizer water level -- maintains water level at an acceptable level in the pressurizer.

3 Reactor coolant pressure control -- maintains reactor i coolant pressure.

4. Co re cooling -- removes the decay heat at hot shutdown conditions as well as the sensible heat during the

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cooldown process. Decay heat removal at hot shutdown conditions is accomplished by maintaining adequate

, water inventory in at least one steam generator.

The safety-related systems that are capable of contributing to the per formance of these functions are given below:

1

1. Negative Reactivity Insertion

The system capable of performing this function is the Reactor Protection System tht-ough insertion of control rods.

2. Pressurizer Water Level Control

. System s capable of performing this function are the CVCS (charging) system and High Pressure Safety Injec-() tion System.

2. Circuit Separation Analysis and Review Page 2-6

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3 Reactor Coolant Pressure Control Pressurizer Heaters and/or CVCS (charging) system.

4. Core Cooling Auxiliary feed water system.

2.6 Results Of Tasks 1 And 2 As was previously discussed , Tasks 1 and 2 identify those fire zones containing redundant safe shutdown equipment which fail to meet the detailed separation criteria of Section III.G.2 i

Appendix R. The seven (7) fire zones identified as a result of

. these tasks are the following:

o Fire Zone 1- Unit 1 Motor Control Center Room

(~) o Fire Zone 2 - Sa fet y Inj ec tio n , Containment Spray k/ Pump Room o Fire Zone 3 - Component Cooling Water Pump Room o Fire Zone 4 - Unit 2 Motor Control Center Room o Fire Area 5 - Auxiliary Feedwater Pump Room o Fire Area 6 - 4160V Switchgear Room o Fire Zone 7 - Monitor Tank Room These areas are snalyzed in detail in Section 4.0 utilizing the methods discussed in Section 3 0 and the appendices.

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s lJ 3. ANALYTICAL METil0DS 31 Background This section discusses the methodology utilized by Wisconsin Elec tric Power Company to demonstrate that verbatim compliance with Section III.G.2 of Appendix R does not enhance the fire protection of the safe shutdown capability of Point Beach Nuclear Po wer Plan t Units 1 and 2 above that provided by the proposed mod i'fic a tion s fo r cable trays identified in Section 4 of this report.

32 Active and Passive Protective Measures In reviewing the fire protection provided by the existing

() con figur ation at Point Beach Nuclear Power Plant Units 1 and 2, only passive protection was considered. The objective of this view is to demonstrate the value of inherent protection assuming the non-operability of active fire protection systems. Thus, the actuation of automatic fire detection and prompt fir e brigade response is not assumed in the analysis. In effect, this analy-sis foc use s solely on the value of separation of combustible materials from the components of interest.

Separation of combustible material from important structures and sys tem s in nuclear power plants as well as between each other typically involves the use of barriers, baffles , coatings ,

and speci fied minimum physical distance in accordance with Commission guidance and requirements (1-5) . These passive meas-

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ures should be viewed as individual elements of fire protection

3 Analytical Methods Page 3-2 f

k and complementary to such active measures as administrative con-trols, detection, and manual suppression, all of which are orien-ted towards inhibiting the initiation of a fire and minimizing the effects once it's started. Yet, in focusing on the value of such passive protection, one should not lose sight of the exist-ence and benefits of the other layers of protection which make up the entire comprehensive fire protection program at Poin t Beach Nuclear Power Plant Units 1 and 2.

33 Passive Protection Analysis As was previously stated , thic analysis concentrates on evaluating only the third aspect of the defense-in-depth approach to fire protection. The goal of plant designs in this context is

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described in Regulatory Guide 1.120 Revision 1 (For Comment) as:

Designing plant safety systems so that a fire that starts in spite of the fire protection programs and burns for a considerable time in spite of fire protec-tion activities will not prevent essential plant safety functions from being per formed.

In order to demonstrate this protection, this analysis makes the following assumptions :

(1) A breakdown of administrative controls in the uncon-trolled introduction of hazardous material in unac-ceptable quantities; I (2) No credit for health physics controls in inhibiting access to safe shutdown areas and the introduction of extraneous material; i (3) A combustible material spill occurs at the worst loca-tion in a fire zone and assumes a geometry which abets the damage of essential systems;

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( ,/ (4) Failure of detection systems to identify the presence of the fire;

3 Analytical Methods Page 3-3 l}

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(5) Fail ur e of the onsite fire brigade to intervene and suppress the fire; (6) Optimal ventilation to fuel the fire at the worst stoichiometric fuel / air ratio combined with sufficient ventilation to maintain the compartment smoke-free (for cpt.imized radiation) without mitigating the damaging of ects of the hot buoyant diffusion plume.

In modeling fires involving the above assumptions, one essentially takes an event whereby an inadvertent breakdown in administrative controls cascades that event through increasingly less likely circumstances and scenarios, i.e., fire initiation and continued burning in the worst possible manner without inter-forence. Additionally, conflicting and even unrealistic require-ments must be simultaneously met so as to ensure that the most damaging effects are modeled through optimum heat transfer from the fire to safe shutdown equipment. -

The details of the modeling process will be discussed later in the report as well as in the appendices. Nonetheless, it should be emphasized that sorst case combinations and values were utilized wherever appropriate so as to ensure that the calculated e f fec ts are suf fic ien tl y conservative to be appropriate in nuclear plant licensing.

34 Heat Transfer An important consideration in the modeling of the fire scenario is the simulation of the associated heat transfer pro-cesses. These processes are affected by room geometry, the

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locations of interest, and reflect the temporal and spatial

3 Analytical Methods Page 3-4 O dependence of radiative, convective and conductive heat transfer.

All of these processes lead to the accumulation of absorbed energy which may also be characterized by a single effective value of temperature at the point of in fluenc e . The absorbed energy, in turn , affects the cable's structural (physical) prop-erties and chemical constituency. With the absorption of a su f fic ien t quantity of energy, pyrolysis will occur leading to ward s ignition of the cable insulation and loss of electrical continuity.

The onset of pyrolysis is determined by the magnitude and duration of exposure to an external heat fl u x . Under suffi-ciently intense exposures, this vaporization yields a net mass

() flux of combustible gases and water vapor above the material's sur fac e . If this vaporization or mass-loss rate is itself high enough to maintain an air / fuel mixture of a critical density above the fuel's surface and the energy needed to support com-bustion' coexists, then a fire would initiate. The critical values for the mass-loss rate and heat flux necessary for igni-

tion- tend to fall within a somewhat confined range for cable l

l  !.u s ul a tio n . The conditions necessary for ignition of cable insu-l lation can, t her e fo re , be defined in terms of the minimum inci-dent heat flux and integrated energy necessary to initiate suffi-cient mass loss rate to support combustion.

35 Heat Flux

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s This analysis focuses on heat flux as a mechanism for mod-

3 Analytical Methods Page 3-5 eling the damage process. The approach used reflects a devel-oping trend in the combustion literature (7-12), i.e., the use of fire models to conservatively predict heat flux conditions as a result of a fire and the relationship of that heat flux to a material's damage process. Research funded by the Electric Power Research Institute at Factory Mutual Research Corporation, for ex am ple , adopted this approach at its inception in 1977 in the aftermath of the Browns Ferry fire (13-17). Similar work in-volving electrical cable fires is currently in progress for the Department of Transportation and has been com pleted fo r the Bureau of Mines for timbers used to support mine galleries. The products of these efforts lay the foundation for a proceduralized evaluation of the effects of exposure fires in power plants based upon rigorous analysis and a physically-based cable damage crite-rion, an approach which is developed further in this analysis. ,

36 Fire Modeling The modeling of physical systems is generally complicated by the effects of multiple variables. The fundamental issue in the development and use of such models is the selection of those parameters which need to be considered and which may be adequate-ly treated through the use of bounding calculational techniques.

This problem is not new to the nuclear licensing process. A classic example exists in the analysis of design basis accidents.

In modeling design basis accidents, assumptions concerning

(') such factors as system failures, line break locations, the cause and flow of natural phenomenon, operator actions under stressful i

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conditions, and the subtle effects of the timing of the sequence of events all impact the analysis and may even contribute to the perceived difficulty in adequately predicting the precise course of important plant parameters. Yet, in concentrating on the important elements in the problem, the question has been and is currently being treated satisfactorily through the judicious and i

careful use of worst case assumptions, the proper application of bounding calculations, and the appropriate selection of extreme values. The result is an analysis which is conservative and suitable for use in the licensing process.

The methods used in this analysis of the effects of fire.on sa fe shutdown systems in nuclear power plants embrace the phi-() losophy and discipline commonly utilized in licensing calcula-tions. Wherever appropriate, worst case assumptions are made to assure the conservative nature of the results. In the following paragraphs, a general discussion is presented for the treatment of the postulated exposure fire using such methods.

l 37 Radiation In modeling fires within a nuclear power plant, the effects of several processes must be considered (Figure 3-1). One such process is the thermal radiation field associated with the band emission of a hot gaseous plume and its soot products. Within the flame front , the dominant emitting species are water vapor, carbon dioxide and soot particles (typically less than 0.1 mic-O rons in size) with over 96% of the radiant energy being emitted

3 Analytical Methods Page 3-7 k- at wavelengths under 15 microns. Total emissivity is directly related to the radiant gas temperature, the gas partial pres-sures, the soot volume-fraction path length, and the radiant gas geometry. The rate of radiant energy transfer is governed by the Stefan-Boltzmann relationship, the flame's emissivity just men-tioned, the absorptivity of the material of interest, and the con fig uration fac to r , i.e., the amount o f the flame seen at any point by the target. From these considerations, it is possible to define the region of influence for radiation which generally exists in the immediate vicinity of a fire and is sensitive, primarily, to the amount of intervening horizontal separation.

While the models used in this analysis consider these elements, the effects of radiation associated with liquid hydrocarbon expo-sure fires of under 20 gallons are generally less significant than those related to the fire plume and stratified gas layers.

38 Turbulent Buoyant Plumes and the Horizontal Jet Flame und buoyant plume impingement is predominantly a turbulent convection problem whereb y hot gases are driven vertically as a result of density differences relative to the ambient gas. As the plume rises, diffusion occurs in the plane normal to the vertical momentum vector which, when combined with some entrainment of cooler gases, results in a decline in the energy at higher elevations. This process is affected by the l

fuel's heat of combustion and the convective heat release ratio l

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(_) which themselves are functions of the fire area, the stage of

! -d evelopment o f the fi r e , the stoichiometric fuel-air ratio, and l

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3 Analytical Methods Page 3-8 d

fuel mass loss rate. The transfer of heat from the plume to any object immersed in it will also be affected by the creation of flow stagi ation points, the presence of baffles, and the location of interest. These processes may be effectively modeled based on experimentally derived correlations and the classical methods o f mathematical physics.

With the impact of the buoyant plume on the ceiling of an enclosure, the vertical momentum vector is converted into a horizontal jet which leads to the development of a str ati fied layer of hot gases extending axisymmetrically outward unless otherwise deflected by corners, walls, and baffles. The coupiing of the ceiling stratification phenomenon with the buoyant plume occurs in the turning region where the classical Gaussian diffu-sion assumptions are modified to ensure continuity of the bound-ary conditions. As a general rule, it may be stated that the convective and radiative heat transfer associated with the stra-

. ti fied ceiling layer at any elevation in an enclosure fire is isotropic outside of the turning region and the fire plume. This e f fec t tends to obscure the beneficial aspects of horizontal separation especially at elevated points within an enclosure.

Di f fusion plumes create intense conditions at the points of influence and dominate the heat transfer process in regions where i they are present. Driven primarily by the convective heat j release rate associated with each fuel in a fire, it is important es to relate the thermal characteristics of the plume with the U

combustion process itself.

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39 The Combustion Process General considerations for convective and radiative heat tr an s fer from a fire to a target material have been previously discussed. This section focuses on the fire itself and those assumptions and considerations which are equally important to the heat transfer and material damage processes.

In general, to maintain the bounding naoure of the fire analysis, it is important that critical parameters assume a worst case condition wherever justification for a lesser case cannot be adequately documented. For modeling the heat release rates in combustion, these parameters are the fuel mass loss rate, the convective-radiative frac tion s , the combustion efficiency, and

{} the heat of combustion. Values for these parameters are keyed to the effects of ventilation which this analysis treats in a unique manner as described below.

Classical analysis of building fir e s , especially those involving residential and office buildings, have attempted to realistically treat ventilation and the effects of drafts on fi r e s . These analyses have extensively discussed the sensitivity of such fires to the effects of ventilation and the problems of modeling these e f fec t s . Our purposes are different. With a fundamental objective of bounding the conditions resulting from a fir e , realistic or "best estimate" scenarios are of merely aca-demic interest and tend to limit the reproducibility of the an al ysi s . Thus, questions concerning draft-limited fires are l

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cally contradictory assumption with regard to ventilation is considered:

(1) Sufficient ventilation to support an optimum stoichio-metric fuel / air ratio at every point in the liquid pool is always assumed to be present without regard to origin.

(2) Sufficient ventilation to maintain the compartment desmoked is always assumed to be present to maximize radiation effects without affecting the stability of any ceiling stratified layers or taking credit for any cooling effects.

Thus, ventilation, an important factor in determining a fire's heat release rate, is treated in a fashion which, although not physically realistic, achieves the goal of being conservative and bounding of the effects of fire.

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3 10 Damage Criterion The final element in the modeling process is that of estab-lishing a damage criterion. As was discussed earlier, the damage criterion needs to be related to the modeling technique. On this basis, the focus of the criteria should be oriented towards the heat flux incident upon the target electrical cable. A fundamen-tal advantage of this approach is that short, hot fires may be related to long, cool fires on similar terms, i.e., the total energy absorbed by the material of interest necessary for a failure process to occur. A secondary advantage of this approach is- that much of the uncertainty surrounding the subject of cable r- resistance to combustion may be reduced.

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To be sure, a damage criterion may also be based on effec-l

3 Analytical Methods Page 3-11 tive temperatures. The difficulty of such an approach, however, is that the association between surface temperature and the damage process is indirect, resulting in a range of temperatures over which failure may occur without an obvious parametric rela-tionship based on the duration of exposure. Such a criterion lacks precision and is, hence, un sa ti s fa c to r y .

The failure concept utilized in this analysis is based on work per formed at Factory Mutual Research Corporation (FMRC)

(10, 12, 13, 17, 18) and discussed in a report to the NRC Staff by Dr. John Boccio of Brookhaven National Laboratory (19) . This approach relates damage in terms of a material's flammability parameters and, in particular, the following two parameters:

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i m (1) Critical heat flux--that incident heat flux above which the cable damage process is expected to occur. .

(2) Critical energy--that amount of energy exposure neces-sary to cause cable failure to occur given a heat flux at or above the critical value.

To develop an energy-based approach to material damage, it is important to review the damage process relative to fire. When exposed to an external heat flux, electrical cable undergoes a series of. damage stages. These stages include the onset of jacket degradation through offgassing , electrical failure, ignition, I

maximum burning, and fire decay. The incident heat flux and energy necessary for a cable to aclieve each stage may be deter-mined under controlled laboratory conditions. One such method r^s

! (_) involves the use of the Factory Mutual Research Corporation combustibility apparatus.

3 An al ytic al Methods Page 3-12 l)

v The FMRC combustibility apparatus, described by Tewarson and Pion (12) and Tewarson et al . (13), allows for the precise meas-urement of a material's flammability properties when exposed to an incident heat flux of 0-70 kW/m2 Measured properties under a given heat flux include: 1) time to failure, 2) mass loss rate,

3) heat release rate, 4) generation rates for gaseous combustion products, and 5) optical transmission. With this data, it is possible to describe a material's fire hazard independent of con ^iguration or the nature of the source of the incident heat fl ux . The basic procedure involves determining the relationship between external heat flux and the time to achievement of a particular stage of damage. Figures 3-2, 3-3, and 3-4 illustrate

() the application of this process to uncoated electrical cables for the cases of: 1) loss of electrical continuity in multi-conduc-tor cable with a 70 Vdc signal, 2) piloted ignition, and 3) auto-ignition.

A review o f Figures 3-2 through 3-4 highlights the intuitive t

nature of the damage process. Where the external energy flux necessary for damage is given as the product of the external heat flux and the duration of exposure required to achieve that damage stage, it is readily apparent that the quantity of energy neces-sary for failure is given by the inverse slope of the linear correlation curve for the plotted data points. The x-intercept of that linear correlation establishes a lower bound for the critical heat flux or the minimum heat flux necessary for damage 7-

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to occur at infinite exposure times. An alternative and more

3 Analytical Methods Page 3-13

) intuitive approach to critical heat flux is illustrated in Figure 3-5 where it is defined as the asymptotic limit fora plot of data points.

3 11 Thermal Shields This section discusses the use of baffles composed of non-combustible or refractory material as an additional protective measure above and beyond that which currently exists at Point Beach Nuclear Power Plan t Units 1 and 2.

Baffles are noncombustible mechanical shields placed between combustible material such as an electrical cable tray and a fire fo r the purpose of either blocking incident radiant energy or d e flec ting hot combustion gases. Although generally not rated for endurance to an incident ASTM-E-119 standard time-temperature oven source, when properly designed and mounted , baffles may be e f fectiv e in protecting against the hazards of exposure fires.

The use of baffles is envisioned as a proposed modification for the purpose of providing substantial additional protection above that which currently exists.

Subsequent to the fir e at Browns Ferry in March 1975, licensees were requested by the NRC to review their existing fire protection features and accomplish necessary and timely improvements. The process utilized involved a fir e hazards analysis which postulated an initial set of assumptions in considering the effects of a fire on the ability to achieve and

() maintain sa fe shutdown conditions. The NRC Staff provided

3 An al ytic al Methods Page 3-14 O

v guidelines for this review in Branch Technical Position APCSB 9 5-1 Appendix A issued in August 1976.

The guidelines of Appendix A provided fo r a flex ible ap-proach to fire protection. While specifying the use of ASTM-rated fire barriers, in areas where such barriers were not fea-sible, licensees could propose alternative methods utilizing flame retardant coatings, suppression systems and other barriers as appropriate. In many cases, such barriers took the form o f non-combustible ba f fles located beneath horizontal electrical cable trays or radiant heat shields for vertical cable tray runs.

For these situations, it is clear that recognition was given to the two principal mechanisms of fire-induced electrical cable b) m failure: convective heating due primarily to fire plume impinge-ment and radiant heating from the hot gaseous and soot combustion products.

Conv ec tiv e heating occurs as a result of the flow of hot gases past an object. The incident heat flux to an electrical cable immersed in a fire plume is a function of the cable jacket

! sur face area exposed , the sur face temperature , the material con-i stituency and the energy of the gas along with its associated l

velocity. This heat flux will vary with cable posiLion within a fire plume as well as the nature of the fire itself. As an l

ex am ple , it is not uncommon for the heat flux to a typical cable exposed to the full impact of a fire plume to be in excess of 80 kW/m2 . At such intensities, cable insulation degradation is

3 Analytical Methods Page 3-15 rapid with failure occurring within several minutes of initial exposure.

Just as convective heating is an important element in cable degradation, radiant heating is also a significant concern with regard to electrical cable survivability to a fir e . In this situation, the important parameters are the effective gaseous temperature, the soot density, the opacity effects of smoke, and the orientation relative to a fire of the electrical cable and its absorptivity. For typical uncoated electrical cables located close to a luminous flame, the radiant heat flux may be in excess of 40-50 kW/m 2 suggesting a rapid cable degradation process.

Cl earl y , in both the convective and radiant heating cases,

( there are distinct benefits to be gained in providing a shield against the intense heat fluxes expected to be developed in the course of a fi r e . The positive aspects of such shields or baf-fles were conclusively demonstrated in a series of tests per-formed by Factory Mutual Research Corporation on behalf of the Electric Power Research Institute. In one test of this series, uncoated electrical cable was placed in a horizontal tray 1 93 m. <

(6 33 ft.) above a 1. 2-m-(3 94-ft .)-diameter pan containing 17 gallons of #2 fuel oil. Located beneath this tray was a 13-mm-(0.5-in.)-thick baffle composed of a non-combustible material . A

" control" tray was left unprotected to document the value of protection provided by the baffle. After 15 minutes of exposure

s. to the source fire , the protected cable tray showed no visible d

3 Analytical Methods Page 3-16 signs of damage while the unprotected cables were severely charred.

Physical tests of this type are indicative of the per form-ance of baffles in protecting cable trays against the effects of exposure fires. A simple , conservative analytical model of the gas dynamics associated with the fire plume suggests the general applicability of these results to closed-sided trays for baffles of the width of the tray. These results are directly applicable to providing additional protection to that inherent in the ex-isting configurations found at Poin t Beach Nuclear Power Plant Units 1 and 2. The configurations at these locations consist of electrical cable run in vertical stacks. The installation of ba f fles to protect these trays would provide significant addi-tional protection against the effects of plume impingement above and beyond that which currently exists. For the situations in this analysis where the existence of baffles is assumed, the use of tray-width baffles was postulated for all closed-sided cable trays as a protective measure against the effects of direct plume impingement. The fundamental concept employed focuses on a nonin-trusive, cost-effective approach to additional protection which would inhibit the flow of hot fire gases past the cables. A I

l similar concept is considered for use as a radiant shield for l

vertical cable runs.

3 12 Summary of the Fire Modeling Process This section reviews the methodology utilized in modeling i

3 Analytical Methods Page 3-17 (3

s_/ exposure fires involving liquid hydrocarbons in nuclear power plants. The historical perspective provided in the Browr s Ferry Report and the previously submitted fire hazard analysis uti-lizing BTP APCSB 9 5-1, Appendix A has been shown to be consis-tent with the exemption process of Appendix R. The missing elements in the earlier process, i.e., the appropriate documenta-tion of the judgment of experienced fire protection engineers, is now provided through the use of bounding analysis of the convec-i tive and radiative effects of exposure fires.

The general approach taken in this analysis is to id en ti fy the minimum quantity and geometry of liquid hydrocarbon spill which would exceed the damage criteria for electrical cable of

- interest. This is accomplished in the following manner :

1) Id en ti fy the electrical cables of interest, their spec i fic a tio n s , g eometr y , and the dimensions of the plant area.

2) Identify the fixed and transient liquid hydrocarbon material of concern.

-3) Calculate the minimum quantity of the fuels of interest and the associated fire geometry (location, area, and depth) necessary to exceed the damageability criteria fo r the id en ti fied electrical cable through the following mechanisms:

a) Str ati fic ation ;

i b) Radiation; c) Buoyant diffusion plume impingement.

Fo r the purposes of analysis, ignore the mitigating l effects of actual room geometry, floor slope, and equipment layout and assume the presence of a perfec.tly horizontal floor free of fire inhibiting equipment.

7 L.)

1 l

l

3 Anal} iical Methods Page 3-18 O Also ignore the mitigating effects of pipes and ventilation systems in diverting the flow of hot gases, absorbing incident heat flux or blocking the free passage of radiation to the cables of interest.

4) When possible, calculate the minimum quantity and geometry of fuel necessary to exceed the same damage criteria for the same cables in the same plant area with protection provided by the use of thermal shields.

The objective of this process is to demonstrate that protec-tion of the public health and safety equivalent to the require-ments of Appendix R,Section III.G.2 will exist and that verbatim compliance with Section III.G.2 will not enhance fire protection of Point Beach Nuclear Power Plant Units 1 and 2. On the basis of standards and guidance embodied in 10CFR50.48c(6) and 10CFR50.12, it may therefore be concluded that the designated plant areas qualify for exemption from the specific requirements of Appendix R,Section III.G.2.

The details of the different processes modeled are presented in the appendices while Section 4 discusses the specific areas evaluated, the assumptions and techniques considered, and the final results.

I, O

Analytical Methods Page 3-19 3

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3 Analytical Methods Page 3-20 O 'O 8 i 6 1 l l l

. . i O Sompte 17 . KPC/ Neoprene 8 -

O Sample 2 . xPE/ Neoprene .

O Somple S .PE/PVC A Somple 6 .PE/PVC A Sompte 8 . EPR/Hypolon i

y _

A Semple il . EPR/Hypolon

, O ,Sornple 59 . EPR/Hypolon

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_g _ (Sompte 56 . Tellon/ Teflon A

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g 2 J' /l t 31 0 3 t g 1 0 10 20 30 50 (0 70 Ealernal Hoot F1wa (kW/m2)

Reproduced from Lee, J. L.. "A Study of Damageability of Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.

Figure 3-2. Electrical Failure of Cables Under Variou's External Heat Flux

3 An al ytic al Methods Page 3-21 Oc , , , . , ,

A $6mple S . P[/PVC e Semple s7. Silicone /Asbestee 9 - a semp#e 87. XPE/ Neoprene -

e 5 e va p+ s .PE/PVC

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. a 5 ample 59. [PR/Hypoten .

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b. 10 20 30 49 SO 90 73 Enternal Hool Flus (kW/m ZI l

Reproduced from Lee, J. L., "A Study of Damageability of Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.

Figure 3-3. Thermal Degradation of Cable Insulations Under Various External Heat Flux l

l

3 Analytical Methods Page 3-22 l

O l i

83 i i i a i i e s2 -

gi , O Sompie 5 . PE/PVC .

o Sompte 59 . EPR/Hypolon o Sompte 60 . Toflon/ Teilon -

• Sompie 22 - Silicone / Asbestos ,

o Sompis 56 - Te flon/Te flon

. A Sompts 57 - Silicons / Asbestos .

A sample 17 . XPE/Neoprent 9 -

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Enternoi Hool Flus IkW/m l Reproduced from Lee, J. L., "A Study of Damageability of Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767 Electric Power Research Institute, Palo Alto, CA, March, 1981.

O risure 3 vitotea 19aiti a or ced1e= oaaer verious External Heat Flux I

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3 Analytical Methods Page 3-23 l I l

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4. ANALYSIS t.ND EXEMPTION REQUESTS A safe shutdown evaluation and associated quantitative fire hazard analysis has been completed for each of the five fire zones and two fire areas in the Point Beach Nuclear Power Pl an t .

y The objective of this analysis is to demonstrate the efficacy of passive fire protection measures alone in protecting redundant sa fe shutdown systems from the effects o f exposure fires inv' olv-

\'

ing. spilled liquld hydrocarbons. No mitigation of the fire resulting from intervention by the fire brigade is credited at any time in the analysis. This section describes the exposure fire effects model employed in this analysis and the fire protec-tion data derived from its execution. Section 4.1 describes the

() development of parameters used in the model, provides an overview of the analysis, and specifies exemption requests based on de-rived data. Scotion 4.2 through 4.8 individually describe the physical characteristics of the fire areas and provide specific data pertinent for each zone / area fire used during execution of

'the model (to simplify the discussion the five fire zones and two fire areas are referred to in this analysis as " fire zones") .

l

l l

l 4.1 Evaluation and An al ysis Page 4-2

([]) 4.1 EVALUATION AND ANALYSIS Safe Shutdown Evaluation A safe shutdown evaluation was performed for all fir e zones at Poin t Beach Units 1 & 2. The purpose of this study was to identify the routing and coexistence of redundant hot shutdown cables with less than twenty (20) feet of horizontal separation.

The safe (hot) shutdown cables identified in each fire zone were grouped into divisions A and B, and are listed in the respective ,

Sections 4.2 through 4.8 Where the existing configurations within the fire zones do

.not comply with the specific requirements of 10CFR50 Appendix R, Section III.G.2, a quantitive fire hazards analysis was performed to evaluate the efficacy of additional modifications which would

((}

provide an equivalent level of protection. This analysis demon-strates that all fire zones, as modified , will provide protection equivalent to that provided by modifications which meet the detailed requirements o f Section III.G.2. A discussion of the

. specific assumptions, considerations and methodology follows.

Analysis The exposure fire effects resulting from the impingement of hot fire gases and radiative heat transfer were modeled to deter-mine both the value of the existing separation in protecting the sa fe . shutdown capability from the effects of exposure fires and the value of additional modifications above and beyond that which o s-(~') .

s e

e 0

l l

4.1 Evaluation and An al ysi s Page 4-3 may have

(]) already been im plemen ted in response to the Bro wn s 's Ferry fire. The objective of this analysis is to demonstrate that any further modifications implemented to achieve verbatim compliance with the detailed provisions of Section III.G.2 of Appendix R beyond those contemplated would not provide additional fir e protedtion safety and may well decrease overall facility safety (10 CFR 50.48 (c)(vi)). On these basis, it will be con-cluded for each fire zone discussed in Sections 4.2 through 4.8, that Wisconsin Electric Po we r Com pa n y , the licensee for Point Beach Units 1 & 2, would have fulfilled its responsibilities under 10CFR50.48 for protecting the safe shutdown capability from the effects of fire and that exemptions from the detailed re-quirements o f Section III.G.2, Appendix R, should be granted n

A/ under the provisions of 10 CFR50.12 and 10CFR50.48. '

In the course of analyzing the possible fir e protection features which currently exist in those areas not in compliance with Appendix R, it was determined that additional protection would be desirable. This additional level of fire protection is reflected in the analysis which is reported herein. The princi-pal focus of the additional protection provided was to achieve that level whereby the effects of ceiling stratification became limiting. The magnitude of stratification effects resulting from an exposure fire is determined by the geometry of the compartment and, especially, the eiling height and the elevations where the cables of concern are located. In effect , passive protection rT becomes limited by the building's structural and architectural

(.)

features. Under these circumstances, additional horizontal sepa-

4.1 Evaluation and An al ysi s Page 4-4 C)

\> ration between redundant safe shutdown systems effected by cable rerouting offers little additional protection.

The level of additional passive fire protection assumed in this analysis is focused on two dimensions: 1) the provision of appropriate protection against the effects of postulated sec-ondary fir es ; and (2) the isolation o f cable fires through the reliance on appropiate measures for inhibitin6 the propagation of fires between cable trays. The implementation of such measures makes use of thermal shields, the flame propagation retardancy of the dominant cable species, cross-linked polyethylene insu-lated cables with neoprene jackets, the thermal lag associated with conduits and, where necessary and where the use is suppor-ted by appropriate engineering analysis for operability, main-tenance, and accessibility, the application of flame-retardant materials. Such combinations of measijres were suggested and implemented by licensees in the 1977 fire hazards analysis per-formed in accordance with the provisions of Branch Technical Position APCSB.9 5.1 Appendix A. Many configurations ret f i ng upon such combinations of measures were approved by NRC Sta ff in individual sa fety evaluation reports (SER's). Moreover, this approach has been designated as the " fourth alternative" by the United States Court Of Appeals for the District of Colombia Circuit in its opinion regarding " Petition for Review of an Order ,

o f the Nuclear Regulatory Commission" .

gss The practical effect of the exemption procedure is thus

(,) to give utilities a fourth alternative : if the company can prove that another network works as well as one of

4.1 Evaluation and An al ysi s Page 4-5

() the three stipulated by the NRC, in light of the iden-ti fied fire hazarcs at its plant, it may continue to employ that method .

(The Connecticut Light and Po wer Compan y et al . v. Nuclear Regula-tory Commission , 2d. Cir., 1982)

It is considered in this analysis that these methods work as well as one of the three stipulated for the following reason.

Although such combinations are not the equivalent of an ASTM-rated fire barrier , such a barrier is unnecessary. Exposure fires tend to be localized and of fairly short duration. Even if secondary fires are ignited, the geometry and size of typical compartments within nuclear power plants would well inhibit the initiation of flashover. Protective measures which address them-selves directly to the hazards of small exposure fires, there-O fo r e , could achieve the level of protection equivalent to that offered by fire barriers without severely affecting the coherence of the unit design.

Of importance in modeling the effects of exposure fires is the selection of materials which are susceptible to ignition and the methods of protection. In this regard the quantities and types of flammable and combustible materials, which may realis-tically be present within each fire zone were considered based on a review of liquid hydrocarbon use and control procedures at the Point Beach Units 1 & 2. The anticipated response time of the site fire brigade was also a factor not to be ignored. It was )

l recognized early in the analysis, however, that such considera- l

/'i tions are greatly dependent upon human performance and any as-(_/

sumptions made regarding their validity would be judgmental. In l

l

l l

4.1 Evaluation and An al ysis Page 4-6 l order to avoid disagreement over the value of judgmental a s's um p-tions, it was decided that a "back-calculation" approach which determines the minimum quantity of fuel and associated fuel geometry necessary to intitiate failure of both divisions would be used. This type of calculation would therefore examine the value of passive protective measures alone protecting redundant divisions from exposure fires which burn to sel f-ex tinguishmen t .

The " bac k-cal c ul atio n" approach essentially assumes the presence of both the fuel and the ignition source necessary to initiate failure in any cable within a tray. Passive protection is provided only by the cable configuration itself without any credit for automatic detection or manual suppression. The prin-cipal advantage of this approach is in bounding the problem s -

under worst case conditions, i.e. the smallest, most damaging fire which burns completely to self extinguishment acting on electrical cables for redundant divisions unimpeded by active fire protection measures. Naturally, this calculational tech-nique leads to postulating the coexistence of the fuel and an ignition source which instantaneously raises the entire quantity of that fuel to its flash point in whatever geometry and location

-is needed to cause the most damage to the cable of concern.

The question of flammable materials suggest three areas for consideration:

1) Designating of the failure criteria for cables of concern.

(~} 2) Addressing the issue of protection for cables of

's- concern from the effects of the initial exposure fir e as well as any secondary fires which may result.

l l

4.1 Evaluation and An al ysis Page 4-7 l

([) 3) Determining an appropiate fuel fo r bounding the values of its flammable properties modeling and (e.g.

heat release rate, mass loss rate, etc.)

Each of these issues will be addressed in turn.

In modeling the effects of these severe fires, the appro-priate selection of a damage criteria is extremely important.

This analysis foc used on the minimum conditions necessary to cause a loss of function through electrical failure i .e . loss of circuit continuity.

In selecting an appropiate damage threshold for this condi-tion, re ferenc e was made to research performad by J.L. Lee of Factory Mutual Research Corporation (FMRC) on behalf of the Elec tric Power Research Institute (17). In analyzing the suscep-2 tibility of 20 electrical cables to fail under varying thermal conditions, two cable specimens with similar characteristics were examined, i.e., polyethylene-insulated multiconductor cables with polyvinylchloride jackets. One cable specimen indicated failure (short circuiting a 70-VDC signal under piloted ignition condi-tions) at an undetermined critical heat flux with a critical energy of 9,070 kJ/m2 The second failed earlier with a critical heat flux of 24 kW/m 2 and a critical energy of 6,530 kJ/m2 This analysis conservatively assumed the lesser criteria of the second cable as a failure criteria.

In the performance of. this analysis the cables of concern were assumed to consist entirely of polyethylene insulated with polyvin ylc hlorid e (PE/PVC) Jackets without regard to actual type.

This assumption was made so as to ensure that _the- cables of

{

4.1 Evaluation and An al ysi s Page 4-8

() concern were assumed to have the worst flammable characteristics possible and, therefore, be bounding for all cases. In reality, PE/ PVC cables represent a small minority of cable types with the majority of safe shutdown po wer , instrument, and control cables being the more fire-resistant cross-linked polyethylene insulated cables enclosed with neoprene jackets (XLPE/N) . Backfit cables now being installed in the Point Beach units are XLPE/N qualified to IEEE-383 and are noted for their non-propagating characteristics.

Having addressed both the failure criteria and the methods of an al ysi s , the only remaining issue is that of selecting the particu'arl fuel to be considered for the calculation. Although any fuel could have been used fo r the calculationc, it was O decided that especially meaningful results would be o f fer ed - if the fuel was one which may be expected to be found within the protected area, thereby reflecting a representative fire hazard.

Initially, gasoline and related liquids such as heptane were considered for this analysis. Gasoline is typically used on-site for official vehicles and is dispensed from underground tanks as required. Such vehicles may enter the truck access bays for work-related activities. Ho wev er , all truck access bays are separated from the fire zones of concern by three-hour-rated fire walls. In addition to official vehicles, Point Beach Nuclear Plant presently has a gasoline-powered portable smoke exhauster with a one-quart fuel tank which is stored with other fire  ;

protection equipment in the turbine building. A one-gallon (O')

gasoline can which is kept in a fire-retardant cabinet in the

I l

4.1 Evaluation and An al ysis Page 4-9 l (O

_) turbine building is used to refuel the smoke exhauster. Ho wev er ,

the turbine building is also separated from all fir e zones by three-hour-rated fire walls. Further, there are no reasonable traffic paths through any fire zone between the underground tank dispenser, the fire-retardant cabinet and the smoke exhauster.

On this basis, bottled gasoline and heptane were excluded from consideration. Simil a rl y , lubricating oil was also excluded on the basis of its infrequent usage, the small quantities used , and the extreme difficulty in igniting and sustaining a lubricating oil fire.

The only liquid hydrocarbon which was considered to be somewhat representative of actual hydrocarbon fire hazards was acetone. Acetone is used within the plant for the cleaning of

(])

stainless steel and in the chemistry lab as a general solvent.

It is stored in bulk quantity outdoors adjacent to a maintenance shop in a locked fi ft y-fiv e (55)-gallon drum. In-plant storage of acetone is limited to one-gallon safety cans kept in a single, locked, controlled-access, fire-retardant cabinet maintained in the Unit 1 containment facade hallway outside of the plant structure. Acetone is dispensed in "Justrite Safety Cans" in pint quantities and returned to the locked safety cabinet after use. Despite its on-site usage in limited quantities, the volatile nature of acetone made it a suitable fuel for modeling purposes.

Acetone (C H 0), an organic solvent which is also water 36

> soluble, is the simplest aliphatic ketone based on the carbonyl  ;

l

4.1 Evaluation and An al ysis Page 4-10

() (C=0) group. With a boiling point of 56 C (132 8 F), it easily vaporizes to form a combustible mixture close to its liquid sur fac e . Appendix A to this report provides a more com plete basis for the rate heat is assumed to be released from the combustion of acetone. The values used are ex tr emel y conservative so as to ensure that the bounding nature of the an al ysis is preserved. A summary of the combustible properties of acetone described in Appendix A is reproduced below:

Heat of Combustion Convective 12.0 kJ/g Radiative 11.4 kJ/g Actual 23 4 kJ/g Theoretical 30.8 kJ/g Vaporization Rate O Highly luminous flame 40.0 g/m 2-s -

Heat Release Rate Convective 480 kW/m2 Radiative 456 kW/m 2 Actual 936 kW/m 2 Except for the modeling of the buildup of the str ati fied layer near the ceilings, all models postulated instantaneous achievement of steady-state combustion conditions. For radiative and plume calculations, this translates to the achievement of a gas temperature of 982 C (1800 F) immediately upon ignition and total flame engulfment of the entire spill sur-#4r e . In addition, steady-state buoyant plume velocities were assumed to be achieved at the same time. The distribution of this energy in a

(

1 compartment is assumed to be an adiabatic process with the

4.1 Evaluation and An al ysis Page 4-11 i

( ') exception of the cables of interest and other nearby combustible material. No heat loss to ceiling, floors, walls, pipes, ducts, or , components is credited at any time unless explicitly stated.

En erg y is accumulated within electrical cable until failure is achieved.

Conclusion Sections 4.2 through 4.8 apply the methods, assumptions and considerations discussed in Sections 3 0 end 4.1 for each fire zone. The objective of the indiv id ual analysis is to demonstrate the value o f a combination o f passive protective measures in protecting the safe shutdown capability of Point Beach Units 1 and 2. In so doing, it will be demonstrated that N-additional modifications to comply with the specific requirements of Appendix R "would not enhance fire protection safety in the fac ilit y" and "may be detrimental to overall facility sa fety."

On these bases, exemptions are requested from verbatim compliance with the specific provisions of Appendix. R under the provisions of 1CCFR50.12 and 10CFR50.48.

i r

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s u s<

4.2 Fire Zone 1 Page 4-12

() 4.2 FIRE ZONE 1: UNIT 1 MOTOR CONTROL CENTER ROOM Description Fire Zone 1 is located in the south wing of the Auxiliary Building at elevation 8'0" and is separated from other adjoining fire zones by non-fire-rated walls at least 18 inches thick. The north and south walls have three-hour-rated fire seals for com-bustible pathway penetrations. Access to the three adjacent CVCS charging pump rooms is via eight (8)-foot-high doorless entrance-ways. Similar entranceways provide connection to adjoining rooms at the north and south ends of this zone. The height of the ceiling is 16 feet 6 inches. Pertinent room dimensional data are contained i r. 4.2.1 Evaluation Parameters Summary Table and

() Figure 4.2-1.

Fire Zone 1 contains Unit 1 safeguards train A motor control center 1-B32, charging pump instrument rack 1RK24 and R24, and charging pump control stations. The fixed combustible loading within this zone is due almost entirely to the cable density and results in a fire loading of 6.0 lb/ ft2 This area has been classified under NFPA standards as C-moderately severe and the expected duration of an uncontrolled , fully-d ev eloped fire is 25 minutes, which correlates to an equivalent fire severity of 20 minutes.

The physical configuration of Fire Zone 1 is not conducive to material storage. Such storage i~s prohibited by plant admini-strative procedures and insurance carrier requirements. Because

(~)

\> of its location , Fire Zone 1 is a passageway frequently traversed

• s

4.2 Fire Zone 1 Page 4-13

() by health physics, operations, and maintenance personnel. While controlled quantities of transient combustible material can be expected to be transported through this zone, any accumulation of such material would be readily noticed and expeditiously removed.

Fire Zone 1 is provided with 3 photoelectric smoke detectors suitably arranged throughout the zone which alarm individually at a local control panel, subsequently providing a common fire zone alarm in the control room. Manual one-and-one-half (1-1/2)-inch ,

hose reel stations are located immediately north and south of the zone and each area of the zone can be covered by a hose stream from both hose reel stations. l Exposure Fire Effects Model (Zone 1 - Pre-Modification)

O' The exposure fire effects of forced convection due to fire plume impingement and stratification were first modeled to deter-mine the degree of passive protection provided by the existing configuration for Fire Zone 1. In this model, horizontal separa-tion offers little inherent protection and the fire zone ceiling and cable tray heights are the important parameters. The limi-ting con figuration for stratification is the two highest redun-dant cable trays, i.e., trays JD and PS. To achieve redundant circuit failure the lowest of these two trays must reach the defined damage criteria which in this case is tray JD at 13 feet.

The smallest quantity of acetone necessary for redundant failure with existing protection would be 14 gallons spilled over_an area

()

with an effective diameter of 7 4 feet. The limiting exposure time is 247 seconds. Ir. this case the model fire would have to  ;

4.2 Fire Zone 1 Page 4-14 O #

be approximately 12mm deep, a depth which is almost fi ft een (15) times greater than that expected from a spill of acetone on a horizontal surface of concrete.

Exposure Fire Effects Model (Zone 1 - With Modifications)

Prior to modeling the limiting exposure fire effects certain specific modifications were proposed for Fire Zone 1. For Fire Zone 1 the minimum horizontal separation which currently exists between redundant safe shutdown trains (PS and JD) is 8 feet 6 inches. In addition to the inherent protection provided by this distance, conduits 1P26, 1P2C1 and 1N11 will be wrapped with an appropriate fire barrier . Cable tray PS will have a non-combus-() tible thermal shield beneath the entire length of the tray from 5 feet south of where conduit 1N11 enters the tray to the north wall of the zone. Cable tray JD will be suitably protected so as not to contribute to the heat load generated by the initial fire.

To cause redundant circuit failure the higher of the two trains must reach the defined failure criteria which in this case is tray PS at 13 feet 10 inches. With the assumed modifications the smallest quantity of acetone necessary for redundant failure l would be 17 4 gallons spilled over a circular area at least 8.8 feet in diameter with the failure criteria achieved within 230 l seconds. The model fire would involve an acetone pool at least 11 mm in depth. Because the minimum required volume of acetone for radiation failure is greater than that necessary for strati-l (~T A- fication I failur e , the proposed thermal shields provide adequate l

l

4.2 Fire Zone 1 Page 4-15 protection to circuits for both divisions (section 4.2.2) in Fire

(])

Zone 1.

It should be noted that the postulated fire diameter is as important as the volume in specifying the smallest quantity of fuel necessary to achieve the damage criteria. Increasing or decreasing the fire diameter would necessitate a fire involving greater quantities of fuel in order to provide the same energy flux at the locations of interest. Smaller diameters would re-quire longer-burning fires with greater fuel depth in order ' t <o achieve the same incident energy flux on a cable while larger diameter fires would implici'ly necessitate larger quantities of fuel to cover the wider area. These results further demonstrate that for the extremely conservative assumptions utilized in this Os/ model, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for both divisions under any circumstances -irrespective of fire location.

Results and Conclusions The stratification model results demonstrate that contain-ment of the 14 gallons of acetone necessary to initiate damage in both divisions to 13 mm of depth, almost 15 times its unconfined spill depth, with a minimum 7.4-foot diameter is an unrealistic condition. Actual plant storage provisions and operating prac-I tices further demonstrate that it would be extremely difficult to accumulate 14 gallons of acetone anywhere within the plant, much

(-)

U less at the precise location and in the precise geometry deter-mined by this analysis to be necessary for redundant cable l

l

4.2 Fire Zone 1 Page 4-16 C) v failure.

In reality, the existing configuration can be expected to provide sufficient passive protection against even greater quan-tities of acetone with the precise value depending on how realis-tically a "best estimate" analysis is per formed . Elements to be considered in such realistic analyses could include the response of automatic detectors and - of installed manual suppression sys-tems in the area, the value of administrative controls in re-ducing the likelihood of substantial fuel quantities, and antici-pated operator actions relative to achieving safe shutdown while a fire is in progress.

Fire Zone 1 relies upon a properly-balanced approach to

() fire protection which includes a comprehensive site fire preven-tion and combustible material control program, the inherent pro-tection provided passively by the existing con fig ur ation , auto-matic detection, and manual fire fighting . This balanced ap-proach was developed in response- to the Browns Ferry fire and reflects the guidance provided by Branch Technical Position APCSB 9 5-1.

The conservative quantitative fire hazards analysis de-scribed herein demonstrates that the addition of the proposed shields will protect Fire Zone 1 safe shutdown cables from elec-trical failure resulting from any reasonable exposure fire postu-lated in the plant regardless of horizontal separation. The moderate combustible louding of Fire Zone 1 together with fir e protection features described in this analysis demonstrate that

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4.2 Fire Zone 1 Page 4-17 O eaaitione1 moairicetions moo 1a not ennence rire grotection er ene sare shutdown capability in Fire Zone 1.

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4.2.1 Fire Zone 1: Evaluation Parameters Page 4-18 O Table 4.2-1 FIRE ZONE 1: UNIT 1 MOTOR CONTROL CENTER ROOM EVALUATION PARAMETERS

SUMMARY

A. Area description l 1. Construction

a. Walls l North - 2'0" aoncrete; 3-hour-rated fire seals for l

combustible pathways South - 2'0" concrete; 3-hour ruted fire seals for combustible pathways l East - 1'6" concrete

() West - 2'0" concrete *

b. Floor - 3'0" concrete; basement

c. Ceiling - 1'6" concrete

2. Ceiling height - 16'6" 3 Room volume - approx. 24,300 ft 3

4. Ventilation - 3250 CFM 5 Congestion - Good access to all sections of this zone, inside radiologically controlled area with moderate t,raffic through zone. G' eral access for manual sup-pression is considered excellent.

e B. Safe Shutdown Equipment

1. Redundant systems in area

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a. Division A: circuits as listed in Section 4.2.2

b. Division B: ircuits as licted in Section 4.2.2

4.2.1 Fire Zone 1: Evaluation Parameter s Page 4-19 i

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4

2. Equipment in area is not required for hot shutdown.

4 .

'The postulated exposure fire is asssumed to be con-tained within the zone walls.

C. Fire Hazards Analysis

1. Type of combustibles in area: electrical cable

2. Quantity of combustibles: the area contains very low quantities of combustible material and the 6.0 lb/ ft 2 I

fire loading is almost entirely due to cable insula-tion.

3 Ease of ignition and propagation: Cable is pol yvin yl-chloride jacketed with polyethylene insulation; appro-priate propagation retardancy is assumed to exist where necessary.

(]).

4. Heat release potential:

PE/PVC Cable f

Heat Relgase Rate

( kW/ M )

convective 228 radiative 131 actual 359 5 Transient' combustibles - Essentially none; only limited

^

quantities (less than'one (1) pint) of acetone used in welding stainless _ steel. The probability of signifi-  !

cant transient combustibles is very low.

i 6. Suppression damage to equipment - Water spray damage-i potential to the equipment due to manual suppression is

{} negligible to the confined area whlch is separated from other safety-related equipment.

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4.2.1 Fire Zone-1: Evaluation Parameters Page 4-20 l 1

O D. Fire Protection Existing

1. Fire detection systems - smoke detection systems; - 3 photoelectric smoke detectors in the fire zone 1

2. Fire extinguishing systems -

J j a. Manual portable extinguishers, 20 PD.C. ( A, B, C)

> b. Manual 1-1/2-inch hose reel station 3 Hose station / extinguisher

a. Distance to hose stations -

1) 10' east j 2) 25' south

b. Disuance to extinguishers -

1) in area

, 2) 30' north i 3) 25' south

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4.2.2 Fire Zone 1: Drawing and Cable Schedule Page 4-22

() UNIT 1 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN Fire Zone 1: Motor Control Center Room l Auxiliary Building, El. 8'0" DIVISION A Conduit Cable Scheme No. Purpose 1P2A ZA1B13AA CVCS Charging Pump 1P2A 1P2A-1 ZA1813AD CVCS Charging Pump 1P2A 1P2B ZA1B13BA CVCS Charging Pump 1P2B 1P2B-1 ZA1B13BD CVCS Charging Pump 1P2B Cable Tray Cable Scheme No. Purpose

() FK05, 06 ZA1B14BA Power Supply to MCC 1B32 JD01, 02, 03 ZA1B13AC CVCS Charging Pump 1P2A i

ZA1813BC CVCS Charging Pump 1P2B JJ04, 05, 06, 07 ZA1813AA CVCS Charging Pump 1P2A ZA1B14AB CVCS Charging Pump 1P2A ZA1813AF CVCS Charging Pump 1P2A ZA1B13BA CVCS Charging Pump 1P2B ZA1B13BB CVCS Charging Pump 1P2B ZA1B13BF CVCS Charging Pump 1P2B QS01 ZA1B13AB CVCS Charging Pump 1P2A ZA1813AC CVCS Charging Pump 1P2A ZA1813AF CVCS Charging Pump 1P2A ZA1813BB CVCS Charging Pump 1P2B-ZA1B13BC CVCS Charging Pump 1P2B ZA1B13BF CVCS Charging Pump 1P2B

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k 4.2.2 Fire Zone 1: Drawing and Cable Schedule Page 4 -23

() DIVISION B Conduit Cable Scheme No. Purpose i 1N11 ZB1B20AB CVCS Charging Pump 1P2C i ZB1820AC CVCS Charging Pump 1P2C

. ZB1B20AF CVCS Charging Pump 1P2C 1P2C ZB1B20AA CVCS Charging Pump 1P2C 4 1P2C-1 ZB1B20AD CVCS Charging Pump 1P2C Cable Tray Cable Scheme No. Purpose PS09, 10 ZB1B20AB CVCS Charging Pump 1P2C i ZB1B20AC CVCS Charging Pump 1P2C l

ZB1B20AF CVCS Charging Pump 1P2C s

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4 3 Fire Zone 2 Page 4-24

() 43 FIRE ZONE 2: SAFETY INJECTION AND CONTAINMENT SPRAY PUMP ROOM Description Fire Zone 2 is located in the center section (south) of the Auxiliary Building at elevation 8'0" and is separated from other zones by two-foot-thick non-fire-rated concrete walls on three a

sides and a twenty-one-inch-thick wall on the west side. The Turbine Building (east) wall is a rated three-hour fir e barrier.

The north, south and west wall s have three-hour-rated fire seals for combustible pathway penetrations. Access to the zones to the north and south is via 8-foot-high doorless entranceways. The height of the ceiling is 16 feet 6 inches. Pertinent room dimen-()

xs sional data are contained in Table 4 3-1 summary Evaluation Parameters and Figure 4 3-1.

Fire Zone 2 contains all safety injection and containment spray pumps for both units. These pumps are safety-related and are required to mitigate the effects of postulated accidents but are not required for sa fe (hot) shutdown. The four safety ;ec-tion pumps are in the east end of the zone spaced at approxi-mately 6 feet between centerlines with the motor end of the A pump aligned with the pump end of the B pump. The four contain-ment spray pumps are located at the west end of the room at approximately 8 feet between centerlines. The motor end of each t

pump is aligned with the pump end of adjacent pumps.

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i Each safety injection pump contains approximately 1 gal 1on

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's J of lubricating oil and each spray pump contains approximately l

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4 3 Fire Zone 2 Page 4-25 m

(_) one-half (1/2) gallon of lubricating oil . The lubricating oil is contained within the pump and can only be considered combustible if it is sprayed upon a hot surface which raises its temperature to above its flash point, i.e., above approximately 450 F. The lubricating oil is not pressurized except during system operation and test. The lubricating oil could not be sprayed from a pos-sible system breach more than approximately 1% of the time (assuming 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> of test per year). Suitable hot surfaces do not exist within this zone except during pump operation. Opera-ting personnel provide an effective fire watch during periods of pump testing. Therefore, due to the limited quantities of lubri-cating oil, the limited pump operation time and lack of credible

, Ignition source, lubricating oil is not considered as a source of combustibles for Fire Zone 2. The fixed combustible loading within .this zone is due almost entirely to the cable density and the cable insulation loading is weighted toward the east end of the room near the safety injection pumps. Breaking the room into two sections more accurately represents the actual fire loading and yields less than 1 lb/ft2 near the spray pumps and 6.9 lb/ft 2 near the safety injection pumps. This area has been classified i as C-mod er atel y severe according to NFPA standards, and the expected fire duration of an uncontrolled , fully-developed fire is 25 minutes, which correlates to an equivalent fire severity of 17 minutes.

The physical configuration of Fire Zone 2 is not conducive -

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to material storage. Such storage is prohibited by plant admini-strative procedures and insurance car ~rier requirements. The only e

4 3 Fire Zone 2 Page 4-26 O floor space within this zone which could accommodate material storage is the aisle passageway between adjoining areas north and south of this zone. This passageway is frequently traversed by health physics, operations, and maintenance personnel. While controlled quantities of transient combustible material can be expected to be transported through this zone, any accumulation of such material would be readily noticed and expeditiously removed.

Fire Zone 2 is provided with three (3) photoelectric smoke detectors suitably arranged throughout the zone which alarm indi-vidually at a local control panel, subsequently providing a common fire zone alarm in the control room. Manual one-and-one-hal f (1-1/2)-inch hose reel stations are located immediately

(} north and south of the zone, and each area of the zone can be covered by a hose stream from both hose reel stations. In addi-tion, a fixed automatic wet pipe suppression system is provided for the safety injection pump and passageway area. The system is automatically initiated and provides a minimum coverage of 03 gpm/ ft 2 of floor area assuming all no zzles are operational.

Pendant nozzles are provided for individual safety injection pump protection.

Exposure Fire Effects Model (Zone 2 - Pre-Modification)

The expasure fire effects of forced convection due to fire plume impingement and stratification were first modeled to de-termine the degree of passive protection provided by the existing A

kJ con figuration for Fire Zone ' 2. In this model, horizor tal separa-l l

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4 3 Fire Zone 2 Page 4-27 tion offers little inherent protection, and the fire zone ceiling

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and cable tray heights are the driving parameters. The limiting con fig ur ation for stratification is the two highest , redundant cable trays, i.e., trays FJ and FL. Both trays exit the zone in a vertical run up through the ceiling and for stratification analy-sis purposes are essentially at ceiling height. The smallest quantity of acete r e ecessary for redundant failure would be 96 Eallons spille. over a circular area at least 6.1 feet in diame-ter with the tailure criteria not exceeded for at least 241 seconds. The model fire would involve an acetone pool approxi-mately 12mm deep, a-depth which is almost fi f teen (15) times greater than that expected from a spill of acetone on a horizon-tal surface of concrete.

( -

Exposure Fire Effects Model (Zone 2 - With Modifications)

Prior to modeling the exposure fire effects of radiation, certain specific modifications were proposed for Fire Zone 2. ,

Cable tray PS of Division B (section 4 3 2) will have a non-

. combustible , thermal shield placed directly beneath the tray; and cable tray FR, also of Division B, will have an appropriate thermal shield placed beneath the tray as well. These shields will extend the entire length of each tray through Fire Zone 2.

The limiting con figur ation for radiation damage due to an ex-posure fire is the lowest redundant circuits which lack adequate horizontal separation. The first set of redundant trains ana-lyzed were trays FR and JD with a minimum horizontal separation b/-)

of one (1) foo t . Pertinent dimensional data on these trays is

4 3 Fire Zone 2 Page 4-28 O

V contained in Section 4 3 1 sketches. With a thermal shield beneath tray FM the minimum volume of acetone necessary to cause redundant failurc would be 20 7 gallons spilled over a circular area at least 9 6 feet in diameter. The damage criteria would not be exceeded for at least 222 seconds requiring a spill depth of approximately 11 mm. The second set of redundant trains requiring radiation analysis is cable trays PS and JD. To cause redundant circuit failure the highest of the two trains must reach the defined failure criteria, which in this case is tray l>S at 13 feet 10 inches. The smallest quantity of acetone necessary for redundant failure with a thermal shield beneath PS would be 17 4 gallons spilled over a circular area at least 8.8 feet in

({} diameter with the failure criteria not exceeded for at least 230 seconds. The model fire would involve an acetone pool at least 11 mm deep. Because the minimum required volumes of acetone for radiation failure are greater than that necessary for stratifica-tion failur e , the proposed radiant energy shields provide ade-quate protection to circuits for both divisions in Fire Zone 2.

It should be noted that the postulated fire diameter is as important as the volume in specifying the smallest quantity of fuel necessary to achieve the damage criteria. Increasing or i decreasing the fire diameter would necessitate a fire involving greater quantities of fuel in order to provide the same energy flux at the locations of interest. Smaller diameters would require longer-burning fires with greater fuel depth in order to O'

'- achieve the same incident energy flux on a cable while larger

4 3 Fire Zone 2 Page 4-29 fires would implicitly necessitate larger quantities of fuel to

[)

cover the wider area. These results further demonstrate that for the extremely conservative assumptions utilized in this model, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for both divisions under any circumstances irrespective of fire location.

Results and Conclusions The stratification model results demonstrate that the con-tainment of the 9 6 gallons of acetone necessary to initiate damage in both divisions to 12mm of depth, almost 15 times its unconfined spill depth, with a minimum 6.1 foot diameter is an unrealistic condition. Actual plant storage provisions and

() operating practices further demonstrate that it would be extreme-ly difficult to accumulate 9 6 gallons of acetone anywhere within the plant much less at the precise location and in the precise geometry determined by this analysis to be necessary for redun-dant cable failure.

In reality, the existing configuration can be expected to provide sufficient passive protection against even greater quan-tities of acetone with the precise value depending on how realis-tically a "best estimate" analysis is per formed . Elements to be considered in such realistic analyses could include the response of automatic detectors and of installed manual suppression sys-tems in the' area, the value of administrative controls in reduc-ing the likelihood of substantial fuel quantities, and antici-pated . operator actions relative to achieving safe shutdown while

4 3 Fire Zone 2 Page 4-30 a fire is in progress.

Fire Zone 2 relies upon a properly-balanced approach to fire protection which includes a comprehensive site fir e prevention and combustible material control program, the inherent protection provided passively by the existinE configuration, automatic de-tection, automatic suppression and manual fire fig hting . This balanced approach was developed inAPCSB 9 5-1.

The conservative quantitative fire hazards analysis de-scribed hereia demonstrates that the addition of the proposed thermal shields will protect Fire Zone 2 safe shutdown cables from electrical failure resulting from any reasonable exposure fire regardless of horizontal separation. The light combustible loading in th^ containment spray pump area together with automa-({}

tic fire suppression in the safety injection pump area and other fire protection features described in this analysis demonstrate 1

that additional modifications would not enhance fire protection of the safe shutdown capability in Fire Zone 2.

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4 3 1 Fire Zone 2: Evaluation Parameters  ? age 4-31 4

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Table 4 3-1 FIRE ZONE 2 : SAFETY INJECTION AND CONTAINMENT SPRAY PUMP ROOM FVALUATION PARAMETErtS

SUMMARY

A. Area description

1. Construction

a. Walls North - 2'0" concrete; 3-hour-rated fire seals for combustible pathways South - 2'0" concrete; 3-hour-rated

! ___ fire seals for combustible pathways East - 2'0" concrete

() West - 1'9" concrete .

b. Floor - 3'0" concrete; basement

c. Ceiling - 1'6" concrete; 3-hour-rated fire seals for combustible pathways

2. Ceiling height - 16'6" 3 Room volume - approx. 24,300 ft3

4. Ventilation - 10980 CFM 5 Congestion - Limited access in vicinity of Safety In-

_jection and Containment Spray pumps, other sections have good access. Inside radiologically controlled area -with moderate traffic through zone. General ac-l cess for manual suppression is considered good.

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4 3 1 Fire Zone 2: Evaluation Parameters Page 4-32 q( ) B. Sa fe Shutdown Equipment

1. Redundant systems in area

a. Division A: circuits as listed in Section 4 3 2

b. Division B: circuits as listed in Section 4 3 2

2. Equipment in area is not required for hot shutdown.

The postulated exposure fire is asssumed to be con-tained within the zone walls.

C. Fire Hazards Analysis

1. Type of combustibles in area:

a. Safety Injection and Containment Spray pump

b. Electrical cable

2. Quantity of combustibles: The area contains very low quantities of combustible material

} a. 8 gallons of oil in lubricating oil systems .

b. 6 9 lb/ ft2 (maximum local) fixed combustible load-ing is almost entirely due to cable insulation.

3 Ease of ignition and propagation:

a. Oil flash point (requires raising oil bulk volume temperature above 450 F)

b. Cable is polyvinylchloride jacketed with poly-ethylene insulation; appropriate propagation re-tardancy is assumed to exist when necessary.

4. Heat release potential:

a. Lubricating Oil Heat Relgase Rate

( KW/ M )

gg convective 728 (j radiative 816 actual 1544

4 3 1 Fire Zone 2: Evaluation Parameters Page 4-33

() b. PE/PVC cable Heat Relgase Rate (KW/M )

convective 228 radiative 131 actual 359 5 Transient combustibles - Essentially none; only limited quantities (less than one (1) pint to 32 fl . oz.) of acetone used in cleaning stainless stee1 prior to weld-ing. The probability of significant transient combus-tibles is very low.

6. Suppression damage to equipment - Water spray damage potential to the equipment due to manual suppression is negligible to the confined area which is separated from other safety-related equipment.

) -

D. Fire Protection Existing

1. Fire detection systems - smoke detection systems, 3 photoelectric smoke detectors

2. Fire extinguishing systems -

a. Automatic wet pipe sprinkler system for coverage of safety injection pumps

b. Manual 1-1/2-inch hose reel station

c. Manual portable extinguishers, 20 #D.C. ( A, B, C) 3 Hose station / extinguisher

a. Distance to hose stations -

1) 48' west on northside

2) 54' north

3) 10' south 4

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1 4 3 1 Fire Zone 2: Evalua tion Parameters Page 4-34

b. Distance to extinguishers -

1) 2' north

2) 20' south O .

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432 Fire Zone 2: Drawing and Cable Schedule Page 4-36 UNIT 1 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN Fire Zone 2: Safety Injection , Containment _ Spray Pump Room Auxiliary Building, El. 8'0" DIVISION A Cable Tray Cable Scheme No. Purpose FJ04 1812BA Pressurizer Heater, Group " C" FK03, 04 ZA1B14BA Power Supply to MCC 1B32 FP06 ZA1813AA CVCS Charging Pump 1P2A ZA1B13AB CVCS Charging Purp 1P2A ZA1B13AF CVCS Charging Pump 1P2A ZA1813BA CVCS Charging Pump 1P2B ZA1813BB CVCS Charging Pump 1P2B

(} ZA1813BF CVCS Charging Pump 1P2B FP07 ZA1B13AB CVCS Charging Pump 1PsA ZA1B13AF CVCS Charging Pump 1P2A ZA1B13BB CVCS Charging Pump 1P2B ZA1813BF CVCS Charcing Pump 1P2B JD01, 02, 03 ZA1B13AC CVCS Charging Pump 1P2A ZA1B13BC CVCS Charging Pump 1P2B JJ08 ZA1B13AA CVCS Charging Pump 1P2A ZA1814AB CVCS Charging Pump 1P2A ZA1B13AF CVCS Charging Pump 1P2A l ZA1B13BA CVCS Charging Pump 1P2B ZA1B13BB CVCS Charging Pump 1P2B ZA1813BF CVCS Charging Pump 1P2B t

DIVISION B Conduit ,C, .le Scheme No. Purpose ,

1P2C ZB1B20AA CVCS Charging Pump 1P2C l

Cable Tray Cable Scheme No. Purpose r,)

'/ FLO2 1B21BA Pressurizer Heater , Group "D" .

1B22CA Pressurizer Heater , Group "E"

432 Fire Zonc 2: Drawing and Cable Schedule Page 4-37

() Cable Tray Cable Scheme No. Purpose l

FM04 1821BC Pressurizer Heater , Group "D" FR04, 05 ZB1B20AB CVCS Charging Pump 1P2C ZB1B20AF CVCS Charging Pump .1P2C ZB1B23CA Power Supply to MCC 1B42 PS10, 11, 12 , ZB1820AB CVCS Charging Pump 1P2C ZB1B20AC CVCS Charging Pump 1P2C i ZB1B20AF CVCS Charging Pump 1P2C '

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I 4.4 Fire Zone 3 Page 4-38 (m_) 4.4 FIRE ZONE 3: COMP 9NENT COOLING WATER PUMP ROOM Description Fire Zone 3 is located in the center section (north) of the Auxiliary Building at elevation 8'0". The concrete east wall separating this zone from the auxiliary feedwater pump area is a rated three-hour fire barrier , and the wall separating zones 2 and 3 is a two-foot-thick non-fire-rated concrete wall. The cable penetrations through the south wall are sealed with three-hour fire-rated barriers to eliminate combustible pathways. Ac-cess to zones 2 and 4 is via eight-foot-high doorless archways.

There is a 10 feet x 12 feet hatch in the ceiling of the west section along with a 15 feet x 4 5 feet stairway in the southeast

(]) section of this zone. The height of the ceiling is 16 feet 6

inches. Pertinent room dimensional data are contained in Table 4.4-1 Evaluation Parameters Summary and Figures 4.4-1 and 4.4-2.

Fire Zone 3 contains the four component cooling water pumps and associated piping and valves. These pumps are not required fo r sa fe (hot) shutdown. Redundant component coolant water pump centerlines are 7 feet 6 inches apart. Units 1 and 2 pump cen-terlines are 16 feet 7 inches apart.

Each component cooling water pump contains only one quart of lubricating oil. The lubricating oil is contained within the pump and can only be considered combustible if it is sprayed upon a hot surface which raises 16 temperature to above its flash point, i.e. above approximately 450 F. Suitable hot sur faces 'do em not exist within this zone. Thus the limited quantities of

4.4 Fire Zone 3 Page 4-39 em

( ,) lubricating oil and lack of credible ignition source removes the component cooling water pump lubricating oil from consideration as a source of combustibles for Fire Zone 3 The fixed combustible loading within this zone is due almost entirely to the cable density and results in a fire loading of 6.6 lb ./ f t .2 This area has been classified as C-moderately severe according to NFPA standards; and the expected fire dura-tion of an uncontrolled, fully developed fire is 50 minutes, 1

which correlates to an equivalent fire severity o f 35 minutes.

The stairway in this fire zone is the principal access to eleva-tion 8'0" of the Auxiliary Building. This access is frequently traversed by plant personnel. While controlled quantities of transient combustible material can be expected to be transported O

kl through this zone, any accumulation of such material would , be readily noticed and expeditiously removed.

Fire Zone 3 is provided with 12 photoelectric smoke detec-tors suitably arranged throughout the zone which alarm individu-ally at a local control panel, subsequently providing a common fire zone alarm in the control room. Two manual one-and-one-hal f (1-1/2)-inch hose reel stations are located in the west end of Zone 3 One hose reel station is located immediately north of Zone 3 and one immediately south of Zone 2. Areas of this zone can be covered by a hose stream from all of these hose reel stations. In addition a fixed automatic wet pipe suppression system is provided for the component cooling water pump area.

f~ This system is automatically initiated and provides

(.s) a minimum coverage o f 0 3 gpm/ f t 2 of floor area assuming all nozzles are

4.4 Fire Zone 3 Page 4-40 O

operational. Pendant nozzles are provided for individual compo-nent. cooling water pump protection.

Exposure Fire Effects Model (Zone 3 - Pre-Modification)

The exposure fire effects of convection due to fire plume impingement and stratification were first modeled to determine the degree of passive protection provided by the existing con-figuration for Fire Zone 3 In the model, horizontal separation 1

offers little inherent protection, and the fire zone ceiling and cable tray heights are the driving parameters. The limiting con fig uration for stratification is the two highest redundant cable trays, i.e., trays FX and FT. Both trays exit the zone in a vertical run up through the ceiling and for stratification analy-sis purposes are essentially at ceiling height. The smallest quantity of acetone necessary for failure is 9 6 gallons spilled over a circular area at least 6.1 feet in diameter with the failure criteria not exceeded for at least 241 seconds. The model fire would involve an acetone pool approximately 12 mm deep, a depth which is almost fifteen (15) times greater than-that expected from a spill of acetone on a horizontal surface of i

j concrete.

Exposure Fire Effects Model (Zone 3 - With Modifications)

Prior to modeling the exposure fire effects of radiation, certain specific modifications were proposed for Fire Zone 3 All sections of Division B cable trays (section 4.4.2) which

4.4 Fire Zone 3 Page 4-41 F

F could be subject to direct fire plume impingement will have appropriate thermal shields placed directly beneath the tray. ,

All remaining horizontal portions of Division B cable trays will be protected by a thermal shield directly beneath the tray.

Division A cable trays will be provided with appropriate protec- '

tion such that they do not contribute to the initial fire's heat i

load. The vertical sections of trays FT and CK will be complete-ly enclosed by a thermal shield. The limiting configuration for radiation damage due to an exposure fire is the lowest redundant circuits which lack adequate horizonta.' separation. Fo r fir e Zone 3 the radiation limiting redundant circuits are cable trays FU and FV. Pertinent dimensional data on these trays is con-  ;

[ tained in section 4.4.1 sketches. With a thermal shield beneath cable tray FU the minimum volume of acetone necessary to cause redundant failure would be 17.4 gallons spilled over a circular

area at least 8 7 feet in diameter. The cable damage criteria would not be exceeded for at least 229 seconds and the model fire would involve an acetone pool approximately 11 mm deep, a depth which is almost fifteen (15 ) times greater than that expected from a spill of acetone on a horizontal surface of concrete.

Because the minimum required volume of acetone for radiation i failure is greater than that necessary for stratification fail-  !

ure, the proposed modifications provide adequete protection to circuits for both divisions in Fire Zone 3 It should be noted that the postulated fire diameter is as important as the volume in specifying the smallest quantity of C (~% 'itel necessary to achieve the damage criteria. Increasing or V

4.4 Fire Zone 3 , Page 4-42

(]) decreasing the fire diameter would necessitate a fire involving greater quantities of fuel in order to provide the same energy flux at the locations of interest. Smaller diameters would require longer-burning fires with greater fuel depth in order to achieve the same incident energy flux on a cable while larger fires would implicitly necessitate larger quantities of fuel to cover the wider area. These results further demonstrate that fo r the extremely conservative assumptions utilized in this model, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for both divisions under any circumstances  ;

irrespective of fire location.

Results and Conclusions O

N/ The stratification model results demonstrate that contain-ment of the 9 6 gallons of acetone necessary to initiate damage

in both divisions to 15 mm of depth, almost 15 times its uncon-fined spill depth, with a minimum 6.1 foot diameter is an un-realistic condition. Actual plant storage provisions and operat-ing practices further demonstrate that it would be ex tremel y difficult to accumulate 9 6 gallons of acetone anywhere within the plant much less at the precise location and in the precise f

geometry determined by this analysis to be necessary for redun-dant cable failure.

In reality, the existing configuration can be expected to provide sufficient passive protection against even greater quan-tities of acetone with the precise value depending on how realis-(")%

1 4.4 Fire Zone 3 Page 4-43 l tically a "best estimate" analysis is per formed . Elements to be considered in such realistic analyses could include the response of automatic detectors and of installed automatic and manual sup-pression systems in the area, the value of administrative con-trols in reducing the likelihood of substantial fuel quantities, and anticipated operator actions relative to achieving safe shut-down while a fire is in progress.

Fire Zone 3 relies upon a properly balanced approach to fire protection which includes a comprehensive site fire prevention and combustible material control program, the inherent protection provided passively by the existing configuration, automatic de-tection, automatic suppression, and manual fire fighting. This

{) balanced approach was developed in response to the Browns Ferr y fire and reflects the guidance provided by Branch Technical Position APCSB 9 5-1.

The conservative quantitative fire hazards analysis de-i scribed herein demonstrates that the addition of the proposed thermal shields will protect Fire Zone 3 sa fe (hot) shutdown cables from electrical failure resulting from any reasonable exposure ' fire regardless of horizontal separation. The most vulnerable redundant cable trays which are id en ti fied as the limiting con fig uratio ns for this analysis are all located within the area of Fire Zone 3 for which automat .c fire suppression is provided. This and other fire protection features described in e this analysis demonstrate that additional modifications would not

() enhance fire protection of the safe shutdown capability in Fire Zone -3

4.4.1 Fire Zone 3: Evaluation Parameters Page 4-44

/D kl Table 4.'l-1 FIRE ZONE 3: COMPONENT COOLING WATER PUMP ROOM .

EVALUATION PARAMETERS

SUMMARY

A. Area description

1. Co n strue,hion

a. Walls North - 2 ' 0"-concrete South - 2'0"-concrete East - 2'0"-concrete; 3-hour-rated fire seals West - 2'0"-concrete

b. Floor - 3'0"-concrete ; basement

(} c. Ceiling - 1'6"-concrete; 3-hour-rated fire seals for combustible pathways.

2. Ceiling height - 16'6" 3 Room volume - approx. 38,100 ft 3

4. Ventilation - 7020 CFM 5 Cong estion - Limited access in vicinity of component cooling water pumps, other sections of area have good access. Inside radiologically controlled area with moderate tra f fic through zone. General access for l

manual suppression is considered good.

B. Safe Shutdown Equipment

1. Redundant systems in area

a. Division A: circuits as listed in Section 4.4.2-

} b. Division B: circuits as listed in Section 4.4.2

4.4.1 Fire Zone 3: Ev al ua tion Parameters Page 4-45

2. Equipment in area is not required fo r hot shutdown.

The postulated exposure fire is asssumed to be con-tained within zone walls.

C. Fire Hazards Analysis l

1. Type of combustibles in area: l

a. Component cooling water system lubricating oil

b. Electrical cable

2. Quantity of combustibles: the area contains very low j quantities of combustible material.

a. 1 gallon of oil in lubricating oil systems

b. 6.6 lb/ f t 2 fixed combustible loading due almost entirely to cable insulation 3 Ease of ignition and propagation:

[])

a. Oil flash point (requires raising oil bulk vol'ume temperature above 450 F)

, b. Cable is polyvinylchloride jacketed with poly-ethylene insulation; appropriate propagation retardancy is assumed to exist where necessary.

4. Heat release potential:

a. Lubricating oil Heat Relgase Rate

( kW/ M )

convective 728 radiative 816 actual 1544 O) l l

l 4.4.1 Fire Zone 3: Evaluation Parameters Page 4-46

()

b. PE/PVC cable Heat Relgase Rate

( kW/ M )

convective 228 radiative 131 actual 359 5 Transient combustibles - Essentially none; only limited quantities (less than one (1) pint) of acetone used in welding stainless steel. The probability of . sig n i fi-cant transient combustibles it very low.

6. Suppression damage to equipment - Water spray damage potential to the equipment is limited due to negligible 4 manual suppression to the confined area and separation O of that suppression from other safety-related e qu,i p-ment.

D. Fire Protection Existing

1. Fire detection systems - smoke detection systems: 12 photoelectric smoke detectors

2. Fire extinguishing systems

a. Automatic wet pipe sprinkler system for coverage of Component Cooling Water Pump Area

b. Manual 1-1/2-inch hose reel system

c. Manual portable extinguishers 20 # DC( A,B, C) 3 Hose station / extinguisher l

a. Distance to hose stations -

l 1) in zone west

! (~}

2) in zone west

3) 10' north l 4) 30' south l

, + - , - - - -- .,

4.4.1 Fire Zone 3: Evaluation Parameters Page 4-47 O b. Distance to extinguishers -

1) in zone

2) in zone

3) 15' north

4) 40' south O .

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432 Fire Zone 3: Drawing and Cable Schedule Page 4-50

( l UNIT 1 CABLE TRAYS AND CONDUIT l NECESSARY FOR HOT SAFE SHUTDOWN Fire Zone 3: Component Cooling Water Pump Room Auxiliary Building, El. 8'0" _

DIVISION B Conduit Cable Scheme No. Purpose 1P2C ZB1820AA CVCS Charging Pump 1P2C Cable Tray Cable Scheme No. Purpose i

CNO3, 04 ZB1B20AC CVCS Charging Pump 1P2C FR06, 07, 08 ZB1820AB CVCS Charging Pump 1P2C ZB1820AF CVCS Charging Pump 1P2C ZB1823CA Power Supply to MCC 1B42 O JE03 ZB1820AC CVCS Charging Pump 1PRC PS12 ZB1B20AB CVCS Charging Pump 1P2C ZB1820AC CVCS Charging Pump 1P2C ZB1B20AF CVCS Charging Pump 1P2C-e

+

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J 432 Fire Zone 3: Drawing and Cable Schedule Page 4-51 (N

\- UNIT 2 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN 1

~

Fire Zone 3: Component Cooling Water Pump Room Auxiliary Building, El. 8'0" DIVISION A Cable Tray Cable Scheme No. Purpose CK01, 02, 03, 04 ZC2B37AC CVCS Charging Pump 2P2A ZC2B37AF CVCS Charging Pump 2P2A ZC2B37BC CVCS Charging Pump 2P2B ZC2B37BF CVCS Charging Pump 2P2B FT03 2B36BA Pressurizer Heater , Group "C" FUO4, 05 ZC2B37AA CVCS Charging Pump 2P2A ZC2B37AB CVCS Charging Pump 2P2A ZC2B37BA CVCS Charging Pump 2P2B CVCS Charging Pump 2P2B O ZC2B37BB ZC2B38BA Power Supply to MCC 2B32 DIVISION B Conduit Cable Scheme No. Purpose FV-3 ZD2B28AC CVCS Charging Pump 2P2C 2B42 ZD2B32CA Power Supply to MCC 2B42 2P2C-1 ZD2B28AA CVCS Charging Pump 2P2C ZD2B28AD CVCS Charging Pump 2P2C 2NP2C-1 ZD2B28AF CVCS Charging Pump 2P2C O

,yy, ,y - ,., ,---y -- y,- . _ . -- - - - , , , - - - .m,

432 Fire Zone 3: Drawing and Cable Schedule Page 4-52 '

1 Division B - Continued Cable Tray Cable Scheme No. Purpose CF03 ZD2B28AA CVCS Charging Pump 2P2C ZD2B28AC CVCS Charging Pump 2P2C ZD2B28AF CVCS Charging Pump 2P2C FV07 ZD2B28AA CVCS Charging Pump 2P2C ZD2B28AB CVCS Charging Pump 2P2C ZD2B28AF CVCS Charging Pump 2P2C FV08, 09 ZD2B28AA CVCS Charging Pump 2P2C ZD2B28AC CVCS Charging Pump 2P2C ZD2B28AF CVCS Charging Pump 2P2C FWO3 ZD2B32CA Power supply to MCC 2B42

FXO4 2B29BA Pressurizer Heater , Group "D" 2B30CA Pressurizer Heater , Group "E" J

4 f

._ ~ _ , _ . _ . . , _ . . . . _ _ _ _ -

()

4.5 FIRE ZONE 4: UNIT 2 MOTOR CONTROL CENTER ROOM ,

Description ,

Fire Zone 4 is located in the north wing of the Auxiliary Building at elevation 8'0" and is separated from other zones by [

non-fire-rated walls at least 18 inches thick. Access to the three adjacent Chemical and Volume Control System charging pump rooms is via e ig ht- foo t-hi g h doorless entranceways. Similar t

doorways provide connection to adjoining rooms at the north and  !

south ends of this zone. The height of the ceiling is 16 feet 6 inches. Pertinent room dimensional data are contained in Table  !

4.5-1 Evaluation Parameters Summary and Figure 4 5-1.  ;

~) This zone contains. Unit 2 safeguards train A motor control center 2-B32, charging pump instrument rack 2RK24 and charging pump control stations. The fixed combustible loading within this zone is due almost entirely to the cable density and has been '

estimated to result in a fire loading of 6 lb/ft2 This zone has (

been classified as C-moderately severe according to NFPA standards and the expected fire duration of an uncontrolled, I fully-developed fire is approximately 25 minutes, which corre- [

lates to an equivalent fire severity of 20 minutes. Because fire zone 4 is located at the north end of the Auxiliary Building, no e i .

traffic route exists for the transport of combustible materials <

through this zone. Transient combustible materials can be expec-ted to be brought into this zone for maintenance purposes and

)

their expeditious removal is required. Accumulation or storage

.-y y w - -,

4.5 Fire Zone 4 Page 4-54

((A) of such materials is not permitted in this zone.

Fire Zone 4 is provided with three (3) photoelectric smoke detectors suitably arranged throughout the zone which alarm indi-vidually at a local control panel, subsequently providing a common fire zone alarm in the control room. Two manual one-and-one-half (1-1/2)-inch hose reel stations are located immediately south of the zone and at the west end of fire zone 3 All areas of this zone can be covered by a hose stream from the hose reel stations.

Exposure Fire Effects Model (Zone 4)

The minimum horizontal separation between redundant sa fe s shutdown trains in Fire Zone 4 is less than one (1) foo t . As N,m\')

shown on the sketch of this zone in Section 4 5 1, this minimum separation is between cable trays JX and JV of Division A (sec-tion 4.5 2) and conduit 2P2C, 2NP2C, and FV3 of Division B. When the exposure fire radiation effects on these redundant circuits were examined it was determined that protective modifications for the Division A and B circuits would be required. As a result, all the conduit of . Division B in zone 4 will be completely covered with an appropriate fire barrier.

The exposure fire effects of convection and stratification were then modeled utilizing the modified configuration for Fire Zone 4. In the stratification model, horizontal separation of-

"fer s little inherent protection and the fire zone ceiling and

( (,/

/~) cable tray heights are the important parameters. The limiting configuration for stratification is a fire near the tran s fo rmer

4.5 Fire Zone 4 Page 4-55 or motor control cabinet of Chemical and Volume Control System charging pump 2P2C. This exposure fire could damage the trans-former or motor control cabinet and , if of sufficient size, could also cause failure of redundant cable tray JV of Division A due to ceiling stratification of hot combustion gas. Thus the lim-iting tray height for this fire condition is 14 feet 3 inches.

The smallest quantity of acetone necessary for failure is 12 3 gallons spilled over an area at least 7 feet in diameter with the failure criteria not exceeded for at least 245 seconds. The model fire would involve an acetone pool and be approximately 12 mm deep, a depth which is almost fifteen (15) times greater than that expected from a spill of acetone on a horizontal surface of

() concrete.

The postulated fire diameter is as important as the volume in specifying the smallest quantity of fuel necessary to achieve

-the damage criteria. Increasing or decreasing the fire diameter would necessitate a fire involving greacer quantities of fuel in

order to provide the same energy flux at the locations of in-terest. Smaller diameters would require longer-burning fires with greater fuel depth in order to achieve the same incident energy flux on a cable while larger fires would implicitly necessitate larger quantities of fuel to cover the wider area. These results further demonstrate that for the extremely conservative assump-tions utilized in this model, it is not possible for lesser

- quantities of acetone to exceed the cable damage - criteria for both divisions under any circumstances irrespective of fire loca-

45 Fire Zone 4 Page 4-56 i

U tion.

Results and Conclusions The stratification model results demonstrate that the con-tainment o f 12 3 gallons o[ acetone', ' the sm'alle st quantity of acetone. necessary to support a fire which fails both divisions, to almost 15 times its udonfined, spill depth is an unrealistic

,. e condition. Ac tual p1' ant st'orage provisions and op6 rating prac- #

s tices further demonstr'hte- tha6 s it would be extrembly difficult ^to 1 ,,s s accumulate 12 3 gallons of acc'.lone" anywhere within the plant much less at the precise location

. .) ~

an( in'the precise geometry 4

deter- s

- s mined by this analysi.n.to ha necessary for redundant cable, O re11ure-n- A + .. .

\ ..

In reality, the, existing donfiguration cad be' expected to

~  ;

provide sufficient passive protection 1against ,even greatee 'quan-' ' '

r tities of acetone'aith the predise val e dependi,n' y

~g [on how realis-tically a "best estimate" anaTysis*is perf0rmed. 41ements to be .

> ,~

y.

y considered in suhh realistic andlyses could . x -

include the resp.onse ~

+, g ,, % j sys-of automatic detectors and or#in'atalled panual suppression c '

tems in the at;ea, the'vaIue drtadmidistr'dtive controls in ,-

s .

- redua x, s.

• the likd1[ hood o.f substantial. fuel q0iint,ities, and-antici-l cing n ,

l v. s_ ,

pated operator act orol relative tc Whieving h sare shutdown 4 while* _

~

w a fire ,is in progress .j , .,

i Fire Zone 4 relies upon a properly balanced approach to fire

! a , ,

l protection which fncludes a comprehensive:, site fft;e prevention n **

l , ,s .s matdrial control program, the inherent protectio,n and combustible s

provided passively' by, the existing con fig uratio n ,- automatic h T  ! s

\V .h  ;

l

-.t _.

4.5 Fire Zone 4 Page 4-57 cm O. L detection, and manual fir e fighting. This balanced approach was developed in response to the Browns Ferry fire and reflects the guidance provided by Branch Technical Position APCSB 9 5-1.

The conservative quantitative fire hazards analysis de-scribed herein demonstrates that the addition of the proposed plant modification will protect Fire Zone 4 safe (hot) shutdown cables from electrical failure resulting from any reasonable exposure fire regardless of horizontal separation. The moderate combustible loading of Fire Zone 4 together with fire protection features described in this analysis demonstrate that manual fire .

t suppression provides suitable protection for Fire Zone 4. This i

and other fire protection features described in this analysis demonstrate that additional modifications would not enhance fire protection of the safe shutdown capability f n Fire Zone 4.

t F

t a

f 1

l

{

I - _

4.5 1 Fire Zone 4: Evaluation Parameters Page 4-58

()

Table 4.5-1 FIRE ZONE 4: UNIT 2 MOTOR CONTROL CENTER ROOM EVALUATION PARAMETERS

SUMMARY

A. Area description

1. Construction

a. Walls No rth - 2 ' 0"-conc rete South - 2'0"-concrete East - 2'0"-concrete; 8"-concrete block, part height 8' West - 2'0"-concrete; 8"-concrete block, part

() height 8'

b. Floor - 3'0"-concrete; basement

c. Ceiling - 1'6"-concrete 1 2. Ceiling height - 16'6" 3 Room volume - approx. 24,900 ft 3

! 4. Ventilation - 680 CFM 5 Congestion - Good access to all seccions of this zone inside radiologically controlled area with moderate tra ffic through zone. General access for manual sup-pression is considered excellent.

B. Safe Shutdown Equipment

1. Redundant systems in area

,_3 a. Division A: circuits are listed in Section 4.5 2 U

2

b. Division B: circuits are listed in Section 4 5 2

4.5 1 Fire Zone 4: Evaluation Parameters Page 4-59 O

2. Equipment in area is not required for hot shutdown.

The postulated exposure fire is asssumed to be con-tained within zone walls.

C. Fire Hazards Analysis

1. Type of combustibles in area: electrical cable

2. Quantity of combustibles: the area generally contains very low quantities of combustible material and the approximately 6.0 lb/ f t 2 fire loading is due almost entirely to cable insulation.

3 Ease of ignition and propagation: cable is polyvinyl-chloride jacketed with cross-linked polyethylene insul-ation; appropriate propagation retardancy is assumed to exist where necessary. ,

4. Heat release potential:

a. PE/PVC cable Heat Relgase Rate

( kW/ M )

convective 228 radiative 131 actual 359 5 Transient combustibles - Essentially none; only limited quantities (less than one (1) pint) of acetone used in welding stainless steel. The probability of sig ni fi-cant transient combustibles is very low.

6. suppression damage to equipment - Water spray damage potential to the equipment due to manual suppression-is

-m l . (_) negligible to the confined area which is separated from l- other safety-related equipment.

l i

4.5 1 Fire Zone 4: Evaluation Parameters Page 4-60 ,

O D. Fire Protection Existing i

1. Fire detection systems - smoke detection systems: j s

three (3) photoel?ctric smoke detectors l

2. Fire extinguishing systems

a. Manual portable extinguishers f

b. Manual 1-1/2-inch hose reel system 3 Hose station / extinguisher

a. Distance to hose stations -

1 i i 1) 5' east at south end i 1 2) 60' west at south end

b. Distance to extinguishers -

1) 20# D.C. ( A, B, C) in room

2) 20# D.C. ( A, B, C) 50' south p

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4.5 2 Fire Zone 4: Drawing and Cable Schedule Page 4-62 UNIT 2 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN i Fire Zone 4: Unit 2 Motor Control Center Room Auxiliary Building, El. 8'0" t

DIVISION A Conduit Cable Scheme No. Purpose 2P2A ZC2B37AA CVCS Charging Pump 2P2A ,

2P2A-1 ZC2B37AD CVCS Charging Pump 2P2A 2P2B ZC2B37BA CVCS Charging Pump 2P2B 2P28-1 ZC2837BD CVCS Charging Pump 2P2B CK05 ZC2B37AC CVCS Charging Pump 2P2A ZC2B37AF CVCS Charging Pump 2P2A I

<S ZC2B37BC CVCS Charging Pump 2P2B s/ ZC2B37BF CVCS Charging Pump 2P2B FUO4 ZC2837AA CVCS Charging Pump 2P2A ZC2B37AB CVCS Charging Pump 2P2A ZC2B37BA CVCS Charging Pump 2P2B ZC2B37BB CVCS Charging Pump 2P2B i ZC2B38BA Power Supply to MCC 2B32 FUO6 ZC2B37AA CVCS Charging Pump 2P2A '

y ZC2B37AB CVCS Charging Pump 2P2A y ZC2B37BA CVCS Charging Pump 2P2B

, ZC2B37BB CVCS Charging Pump 2P2B

, ZC2B38BA Power Supply to MCC 2B32

• HA01 ZC2B37AB CVCS Charging Pump 2P2A 1

ZC2B37AC CVCS Charging Pump 2P2A l t ZC2B37AF CVCS Charging Pump 2P2A l ZC2B37BB CVCS Charging Pump 2P2B i

ZC2B37BC CVCS Charging Pump 2P2B ZC2B37BF CVCS Charging Pump 2P2B l

[ JV04, 05 ZC2B37AC CVCS Charging Pump 2P2A l ZC2B37AF CVCS Charging Pump 2P2A ZC2837BC CVCS Charging Pump 2P2B ,

g-) ZC2B37BF CVCS Charging Pump 2P2B l \J l

I

i 452 Fire Zone 4: Drawing and Cable Schedule Page 4-63 Cable Tray Cable Scheme No. Purpose Division A-Continued JX03 ZC2B37BA CVCS Charging Pump 2P2B ZC2B37BB CVCS Charging Pump 2P2B JX04, 05 ZC2B37AA CVCS Charging Pump 2P2A ZC2B37AB CVCS Charging Pump 2P2A ZC2B37BA CVCS Charging Pump 2P2B ZC2B37BB CVCS Charging Pump 2P2B DIVISION B Conduit Cable Scheme No. Purpose FV-3 ZD2B28AC CVCS Chargind Pump 2P2C 2N11 2B29BE CVCS Charging Pump 2P2C 2P2C ZD2B28AA CVCS Charging Pump 2P2C 2P2C-1 ZD2B28AA CVCS Charging Pump 2P2C r) 2NP2C ZD2B28AD ZD2B28AB CVCS Charging Pump 2P2C CVCS Charging Pump 2P2C ZD?B28AF CVCS Charging Pump 2P2C 2NP2C-1 ZD2B28AF CVCS Charging Pump 2P2C ~

/~N

\_

9 - + e

4.6 Fire Area 5 Page 4-64

(~h sl 4.6 FIRE AREA 5: AUXILIARY FEEDWATER PUMP ROOM Description Fire Area 5 is located in the west side of the Control Building at elevation 8'0" and all walle have three-hour-rated fire seals. The area boundaries are three-hour-rated fire bar-riers with three-hour fire-rated doors , and the area surrounds a three-hour fir e-rated tunnel between turbine halls. The height of the ceiling is 17 feet 2 inches. Pertinent room dimensional data are contained in Tabl e 4. 6-1 Evaluation Parameters Summary and Figures 4.6-1 and 4.6-2.

This area contains four (4) auxiliary feedwater pumps (2 steam-driven, 2 electric motor-driven), the remote shutdown pa-nels fo r operation of the electric auxiliary feed water pudps, containment cooling fan s , and room ventilation equipment. The auxiliary feed wa ter system ie .~equired for sa fe hot sh ut di. cn .

Each steam-driven pump is 100% capacity and dedicated to a single unit while each electric motor-driven pump is 50% capacity and capable of supplying feedwater to one division of either Unit 1 or 2. Each pump is in an individual bay isolated from the other pumps by a floor-to-ceiling non-rated concrete wall one (1)-foot thick.

Each emergency feedwater pump contains approximately one-hal f (1/2) gallon o f lubricating oil . The lubricating oil is

~ contained within the pump and can only be considered combustible (hf -1f it is sprayed upon a hot surface which raises its temperature

--to above its flash point , i.e. above approximately 450 F. The

4.6 Fire Area 5 Page 4-65 O

lubricating oil is not pressurized except during system operation and test. The lubricating oil could not be sprayed from a pos-sible system breach more than approximately 1% of the time (assu-ming 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> of test per year) . Suitable hot surfaces do not exist except during pump operation. Operating personnel provide an effective fire watch during periods of pump testing. There-fore, due to the limited quantities of lubricating oil, the limited pump operation time, and limited probability of a credi-ble ignition source, lubricating oil is not considered as a source of combustibles for Fire Area 5 The fixed combustible loading within this area is due almost entirely to the cable density and the overall fire loading is l'a

(,_/ three (3) lb/ft2 ,This area has been classified as C-moderately severe according to NFPA standards and the expected fire duration of an uncontrolled, fully developed fire is 30 minutes, which correlates to an equivalent fire severity of 20 minutes.

Plant administrative procedures and insurance carrier re-quirements prohibit the storage of combustible materials in this fire area. The auxiliary feedwater pump room is not a path for personnel traffic . The security requirements for access to this room make it inconvenient for storage of transient materials.

While transient combustible materials can be expected to be l brought into this area for maintenance purposes their expeditious removal is required.

<~s Fire Area 5 is provided with eleven (11) photoelectric smoke V ,, detectors suitably arranged throughout the area which alarm indi-3

4.6 Fire Area 5 Page 4-66 (m

(_) vidually r. c a local control panel, subsequently providing a common fire area alarm in the control room. Two manual one-and-one-half (1-1/2) hose reel stations are located outside the zone and manual coverage from both hose reel stations is possible for Fire Area 5 In addition, an automatic single fail ur e-proo f halon suppression system is being installed in this area.

Analysis of Fire Area 5 The first step of the analysis for Fire Area 5 was to sepa-rate sa fe shutdown circuits according to the applicable unit.

The Unit 1 cables are generally located in the southern section of this area and the Unit 2 cables are located in the northern section. Next, those circuits already meeting the requirements of Appendix R were identified.

• Cables fo r Service Water pumps are already in compliance with the requirements of 10CFR50 Appendix R, Section III.G.2.b in that redundant circuits are separated by at least twenty -(20) feet of horizontal distance with no intervening combustibles or fire hazards. Any two of the six Service Water Pumps will pro-vide sufficient service water to maintain sa fe hot shutdown conditions. As sho wn on the cable schedules and sketches in Section 4.6.2, the redundant cable trays for Service Water pump po wer are trays EC and FR in the south section of the room and trays FU and FV in the north section. Trays FV and EC contain cables for two (2) Service Water pumps in each tray; ther e fo re ,

(') in order to cause failure of redundant Service Water trains, a

. single exposure fire would have to cause failure of both trays FV i

l t

4.6 Fire Area 5 Page 4-67

)

('J

~

and EC. These trays are separated by a minimum horizontal dis-tance of at least fifty (50) feet and for this reason the analy-sis of fire area 5 does not consider servico Water pump cables.

The cables for auxiliary feedwater pumps were also examined for adequate separation. Both of the steam driven auxiliary ,

feedwater pumps are mounted on pedestals such that direct flam e impingement on the pump itself is not possible. To damage both ofthese massive, strictly mechanical pumps by radiation only  ;

would require an exposure fire of such a magnitude that hot gas stratification would cause prior failure of redundant cable trays of other safe shutdown systems in this area. In addition, these pumps do not require any electrical power for local manual con- i

() trol and the motor operated steam supply valves are located outside of fire area 5 Ther e fo re , fire damage to the steam supply valves could not affect operation of the electric motor driven auxiliary feedwater pumps. Each steam driven pump is also separated from at least one electric motor driven pump by more l

l than twenty C'0) feet of horizontal distance. For this reason  ;

l .

i the analysis of Fire Area 5 does not consider the auxiliary l feedwater pump cables.

I Unit 1 Exposure Fire Effects Model ( Area 5 - Pre-Modification)-

l The exposure fire effects of convection and str ati fic ation were first modeled to demonstrate the degree of passive protec-7s tion provided by the existing configuration for Unit 1 circuits

(-) in Fire Area 5 In the stratification model, horizontal separa-

4.6 Fire Area 5 Page 4-68

() tion offers little inherent protection and the fire area ceiling and cable tray heights are the important parameters. The lim-iting configuration for stratification is the two highest redun-dant cable trays, i.e., trays FR and FK or FJ and FM with the lower of the trays at a height of 13'10". The smallest quantity of acetone necessary for failure is 12 9 gallons spilled over a circular area at least 7 1 feet in diameter with the failure criteria not exceeded for at least 245 seconds. The model fire would involve an acetone pool be approximately 12mm in depth, a depth which is almost fifteen (15) times greater than that expec-ted from a spill of acetone on a horizontal surface of concrete.

Unit 1 Exposure Fire Effects Model ( Area 5 - With Modifications)

Prior to modeling the exposure fire effects of radiation , on Unit 1 circuits, a specific modification was proposed for Fire Area 5 Cond uit 1P2C1 will be wrapped with a 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> rated fire barrier over its entire length through Fire Area 5.

For Unit l' i n fire area 5 the limiting redundant cables are all located west of the tunnel through the room. The minimum horizontal separation between redundant cables west of the tunnel 4

is 11'6" with the lowest trays of concern being FJ of Division A l

l (Section 4.6.2) at a height of 13'10" and FM o f Division B at a height o f 12 ' 10" . Both trays contain Pressurizer Heater power cables. The smallest quantity of acetone necessary for redundant failure of trays FJ & FM due to radiation would be 12 7 gallons wi~th the fire centerline equidistant from both trays.

(]) The fire diameter would have to be 10.2 feet and the failure criteria

4.6 Fire Area 5 Page 4-69 (m

(-) would not be exceeded for at least 123 seconds. The model fire would be approximately 6mm in depth, a depth which is almost eight (8) times greater than that expected from a spill of ace-tone on a horizontal surface of concrete.

The minimum required volumes of acetone necessary for fail-ure due to radiation and stratification are within 2% of one another. Additional modifications would not enhance fire protec-tion of the safe shutdown capability for Unit 1 in fire area 5 Unit 2 Exposure Fire Effects Model ( Area 5 - Pre-Modifications)

As with Unit 1, the limiting redundant hot sa fe shutdown circuits for Unit 2 are located west of the tunnel. Cable trays O FU and FV east of the tunnel contain only Service Water cables which do not require analysis as previously discussed.

The exposure fire effects of convection and stratification were first modeled to demonstrate the degree of passive protec-tion provided by the existing configuration for Unit 2 circuits in Fire Area 5 The limiting configuration for strati fic ation is the two highest redundant cable trays, i.e., trays FT and FX, with the lower tray at a height of 14'10". The smallest quantity of acetone necessary for failure is 11 5 gallons spilled over a circular area at 1 cant 6 9 feet in diameter with the failure criteria not exceeded for at least 252 seconds. The model fire would involve an acetone pool approximately 12mm deep, a depth whic h is almost fifteen (15) times greater than

(]) that expected from a spill of acetone on a horizontal surface of concrete.

4.6 Fire Area 5 Page 4-70 Unit 2 Exposure Fire Effects Model ( Area 5 - With Modifications)

Prior to modeling the exposure fire effects of radiation on Unit 2 circuits; certain specific modifications were proposed for Fire Area 5 Cable tray FU will have an appropriate fire plume impingement barrier placed directly beneath the tray. The bar-rier will extend the entire length of tray FU from five (5) feet west of where the dividing wall between redundant trains ends to the point where tray FU is over the tunnel ceiling. Cable tray FT will have a thermal shield placed directly beneath the tray, and this shield will extend five (5) feet west of where the wall between the redundant trains end to the point where tray FT is

() over the tunnel. For Unit 2 fire area 5 the minimum horizontal separation between redundant hot safe shutdown circuits is 3 f'eet 6 inches. The limiting con figuration is the lowest redundant trains, i.e., cable trays FU and FV at 12 feet 10 inches. The smallest quantity of acetone neessary for redundant failure would be 15.2 gallons spilled over a circular area at least 8 feet in diameter with the failure criteria not exceeded for at least 235 seconds. The model fire would involve an acetone pool at least 11 min d ee p , a depth which is almost fifteen (15) times greater than that expected from a spill of acetone on a horizontal sur-face of concrete. Because the minimum required volume for radia-tion failur e is greater than chat necessary for stratification A

failure, the proposed modifications provide adequate protection

\"

to Unit 2 hot shutdown circuits.

4.6 Fire Area 5 Page 4-71

() The postulated fire diameter is as important as the volume in specifying the smallest quantity of fuel necessary to achieve the damage criteria. Increasing or decreasing the fire diameter would necessitate a fire involving greater quantities of acetone in order to provide the same energy flux at the locations 'o f interest. Smaller diameters would require longer-burning fires with greater fuel depth in order to achieve the same incident energy flux on a cable while larger fires would implicitly neces-sitate larger quantities of fuel to cover the wicer area. These results further demonstrate that for the extremely conservative assumptions utilized in these models, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for both divisions under any circumstances irrespective of fire location.

Results and Conclusions The existing plant storage provisions and operating prac-tices demonstrate that it would be extremely difficult to accumu-late anywhere in the plant the specific quantities of acetone determined by this analysis to be necessary to initiate cable failur e . The further restriction of these quantities of acetone to the precise geometries and locations determined by this analy-sis to be necessary to initiate cable failure is an unrealistic condition.

In reality, the exis ,ing configuration can be expected to provide sufficient passive protection against even greater quan-(]

U tities of acetone with the precise value depending on how realis-

4.6 Fire Area 5 Page 4-72 O tically a "best estimate" analysis is per formed . Elements to be considered in such realistic analyses could include the response of automatic detectors and of installed automatic and manual sup-pression systems in the area, the value of administrative con-trols in reducing the likelihood of substantial fuel quantities, and anticipated operator actions relative to achieving safe shut-down while a fire is i progress.

Fire Area 5 relies upon a properly balanced approach to fir e l protection which includes a comprehensive site fire prevention f

and combustible material control program, the inherent protection provided passively by the existing configuration, automatic det-ection, single failure-proof automatic fire suppression, and manual fire fighting. This balanced approach was developed

(]) '

in response to the Browns Ferry fire and reflects the guidance provided by Branch Technical Position APCSB 9 5-1. '

The conservative quantitative fire hazards analysis des-cribed herein demonstrates that the addition of the proposed '

plant modifications will protect Fire Area 5 safe (hot) shutdown cables from radiation- induced electrical failure from any rea-sonable exposure fire regardless of horizontal separation. Fire detection and automatic fire suppression is provided for Fire Area 5 in compliance with Appendix R Section III.G. This and other fire protection features described in this analysis demon-strate that additional modifications would not enhance fire pro- ,

tection of the safe shutdown capability in fire zone 5

()

4.6.1 Fire Area 5: Evaluation Parameters Page 4-73

() Table 4.6-1 FIRE AREA 5: AUXILIARY FEEDWATER PUMP ROOM EVALUATION PARAMETERS

SUMMARY

A. Area description

1. Construction

a. Walls North - 1'6" concrete; 3-hour-rated fire seals South - l'6" concrete; 3-hour-rated fire seals l i

East - 1'6" concrete; 3-hour-rated fire seals West - 1'6" concrete; 3-hour-rated fire seals

b. Floor - 10" concrete; basement y c. Ceiling - 10" concrete; 3-hour-rated fire seals

2. Ceiling height - 17'2" -

3 Room volume - approx. 63,000 ft3

4. Ventilation - 8000 cfm

5. Congestion - Access to this area is automatically con-trolled by the station security system. General access for manual suppression is considered excellent.

B. Safe Shutdown Equipment

1. Redundant systems in area

a. Division A: circuits as listed in Section 4.6.2

b. Division B: circuits as listed in Section 4.6.2

2. Equipment in area required for hot shutdown are Em er-gency Feedwater pumps. The postulated exposure fire .is f^T assumed to be contained within the area.

V

~

l

4.6.1 Fire Area 5: Ev al ua tion Parameters Page 4-74

() C. Fire Hazards Analysis

1. Type of combustibles in area:

a. Emergency Feedwater system lubricating oil

b. Electrical cable

2. Quantity of combustibles: the area gererally contains very low quantities of combustible material

a. 2 gallons of oil in lubricating oil systems 2 fixed combustible loading due

b. 30 lb/ ft almost entirely to cable insulation.

3 Ease of ignition and propagation:

a. Oil flash point (requires raising oil bulk volume temperature above 450 F)

b. Cable is polyvinylchloride jacketed with polyethy-O lene insulation; appropriate propagation retardan-cy is assumed to exist where necessary.

4. Heat release potential:

a. Lubricating oil Heat Relgase Rate

( kW/ M )

5 convective 728 radiative 816 actual 1544 t

b. PE/PVC cable Heat Relgase Rate

( kW/ M ) l convective 228 radiative 131 actual 359 m

a 4.6.1 Fire Area 5: Evaluation Parameters Page 4-75

(]) 5 Transient combustibles - Essentially none; only limited quantities (less than one (1) pint) of acetone used in welding stainless steel.

6. Suppression damage to equipment - Water spray damage potential to the equipment due to manual suppression is negligible to the confined area, which is separated from other safety-related equipment.

D. Fire Protection Existing

1. Fire detection systems - smoke detection systems; ele-ven (11) photoelectric smoke detectors

2. Fire extinguishing systems

a. Automatically actuated single failure proof Halon system t

b. Manual 1-1/2-inch ho se reel system ,

c. Manual portable extinguishers

1) 20# D.C. ( B)

2) 150# D.C. ( A, B, C) wheeled

3) 20# D.C. ( B)

4) 20# D.C. ( A, B, C) 3 Hose station / extinguisher

a. Distance to hose stations

1) 30' east on nortn side

2) 15' east on south side

b. Distance to extinguishers 1).10' east on south side

2) 15' cast on south side l

3) 5' west on north side

{} 4) 25' east on north side 1.

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4.5 2 Fire Area 5: Dr awing and Cable Schedule Page 4-78

(

UNIT 1 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTD0l!N Fire Area #5 - Auxiliary Feed Pump Room Control Building, El. 8'0" DIVISION A Conduit Cable Scheme No. Purpose P38A ZE1812CA Aux. FW Pump P38A Cable Tray Cable Scheme No. Purpose 1EC01 ZE1B10CA SW Pump P38A ZE1B10CD SW Pump P38A ZE1B11CA SW Pump-P38B ZE1811CD SW Pump P38B FJ01, 02, 03, 04 1B12BA Pressurizer Heater, Group C

(]}

FK02, 03 ZA1B14BA Sa feguards MCC 1B32 FPO4 ZED 1128A 125 VDC Distribution Panel, D11 ZED 1201A 125 VDC Distribution Panel, D12 ZED 1211A 125 VDC Distribution Panel, D12 ZED 1620A 125 V DC Distribution Panel, D16 FP05, 06 ZA1B13AA CVCS Charging Pump 1P2A ZA1B13AB CVCS Charging Pump 1P2A ZA1813AF CVCS Charging Pump 1P2A ZA1813BA CVCS Charging Pump 1P2B ZA1D13BB CVCS Charging Pump 1P2B ZA1813BF CVCS Charging Pump 1P2B DIVISION B

, Cable Tray Cable Scheme No. Purpose r~ FLO1, 02 1B21BA Pressurizer Heater, Group D l

( )s 1B22CA Pressurizer Heater, Group E l

l l

j i

452 Fire Ar'ea 5: Drawing and Cable Schedule Page 4-79

(]) Division B - Cont'inued FM02, 03 1B21BC Pressurizer Heater , Group D l FR02 ZF1820CA SW Pump P32C

ZF1820CD SW Pump P32C

Cable Tray Cable Scheme No. Purpose I

FR03 ZB1B20AB CVCS Charging Pump 1P2C ZB1B20AF CVCS Charging Pump 1P2C ,

l ZB1823CA Safeguards MCC 1B42 j ZF1820CA SW Pump P32C ZF1B20CD SW Pump P32C e

3 4

1 l-l (:)

f  :

4.5 2 Fire Area 5: Drawing and Cable Schedule Page 4-80

() UNIT 2 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN Fire Area #5 - Auxiliary Feed Pump Room Control Building, El. 8'0" DIVISION A ,

Cable Tray Cable Scheme No. Purpose FT01, 02, 03 2B36BA Pressurizer Heater, Group C FUO1 ZE2B34BA SW Pump P32F ZE2B34BB SW Pump P32F FUO2 ZE2B34BA SW Pump P32F ZE2B34BB SW Pump P32F FUO3, 04 ZC2B37AA CVCS Charging Pump 2P2A ZC2B37AB CVCS Charging Pump 2P2A

_ ZC2B37BA CVCS Charging Pump 2P2B O ZC2B37BB ZC2B38BA CVCS Charging Pump 2P2B Safeguards MCC 2B32 .,

DIVISION B Conduit Cable Scheme No. Purpose P38B ZF2B31CA Aux . FW Pump P38B Cable Tray Cable Scheme No. Purpose FV03 ZF2B27BA SW Pump P32D ZF2B27BB SW Pump P32D ,

~

ZF2B27CA SW Pump P32E ZF2B27CB SW Pump P32E FV04 ZF2B27BA SW Pump P32D ZF2B27BB SW Pump P32D i ZF2B27CA SW Pump P32E ZF2B27CB SW Pump P32E FV05, 06, 07 ZD2B28AB CVCS Charging Pump 2P2C FW51, 02, 03 ZD2B32CA Safeguards MCC 2B42

.O

(_) FX01, 02, 03, 04 2B29BA Pressurizer Heater, Group D 2B30CA Pressurizer Heater, Group E

47 Fire Area 6 Page 4-81

()

V 47 FIRE AREA 6: 4160 SWITCHGEAR ROOM Dascription Fire Area 6 is located in the center of the Control Building at elevation 8'0" immediately east of Fire Area- 5 The walls enclosing area 6 are three-hour-rated fire barriers with three-hour-rated fire seals. The west wall door to Fire Area 5 and the south wall door to the Unit 1 turbine hall are three-hour fi r e-rated doors and the doors to the plant battery rooms are one-and-one-half (1-1/2)-hour fire-rated doors. The height of the ceiling is 17 feet 2 inches. Pertinent room dimensional data are contained in Table 4 7-1 Evaluation Parameters Summary and Figures 4.7-1 to 4 7-4.

(m Fire Area 6 contains safeguards switchgear for both trains A

'd and B of Units 1 and 2. Sa fety-related cable trays, condu't,i distribution panels and battery chargers for the station ESF batteries are also present. The fixed combustible loading within this area is due almost entirely to the cable density and results in a fire loading of 13 5 lb./ft.2 This area has been classi-fied as C-moderately severe according to NFPA standards and the expected fire duration of an uncontrolled , fully-developed fire is 115 minutes which correlates to an equivalent fire severity of 100 minutes.

Because of its location and security access requirements, Fire Area 6 is not a path for personnel traffic. No quantities l

l of transient combustible material are expected to be transported

\

(_) through this area nor are any such materials expected to be

47 Fire Area 6 Page 4-82

() introduced for maintenance purposes. Plant administrative p'ro-cedures and insurance carrier requirements prohibit material storage in this area and such material should be readily noticed and expeditiously removed.

Fire Area 6 is provided with six (6) photoelectric smoke detectors suitably arranged throughout the area which alarm indi-vidually at a local control panel, subsequently providing a common fire area alarm in the control room. Manual one-and-one-hal f (1-1/2)-inch hose reel stations are located immediately north and south of Fire Area 6 for manual fire suppression capa-bility. In addition,' a single failure-proof, automatic Halon fire suppression system will be installed in this area. The suppression system will discharge sufficient Halon for fire ex-A

\- tinguishment approximately ninety (90) seconds after ignition, and will provide positive indication of system operation to the control room.

Analysis of Fire Area The first step of the fire hazards analysis for Fire Area 6 was to identify those circuit redundancies within the area not <

meeting the horizontal separation requirements of 10CFR50 Appen-i dix R,Section III.G.2. Each cable tray and conduit required for sa fe hot shutdown was segregated as according to unit or common plant function. For each functional grouping the cables were t

, further divided in Division A and Division B. These cables are ,

L i

{} listed in section 4 7 2. Division A cables are generally located in the south and east sections while Division B cables are gener- [

x,-

47 Fire Area 6 '[ Page 4-83 ally located in the nort$ 'and west sections of this area.

Detailed sketches of Unit 1, ,

Unit 2<and common plant cable trays and conduit. are contained in Section 4 7 2.

After id en ti fic ation of cable trays and conduits required for hot shutdown , each was examined t'o determine if that particular cable had a redundant circuit within fire area 6. Once circuit redundancies were identified, those circuits separated by at least twenty (20) fee t of horizontal distance were eliminated from consideration as already meeting the requirements of Appendix R. Those few re-maining r ed und an t circuits required quantitative fir e hazards analysis to justify existing configurations or to recommend plant mod i fic atio ns . These redundant circuit pairs are listed in Sec-() tion 4 7 3 Once the circuits requiring further analysis were identif'ied several Sounding calculations were performed to identify the circuits requiring specific detailed analysis. The first step was to determine the limiting redundant hot shutdown circuits which could fail due to ceiling stratification of hot combustion gases. Because failure due to this process is by hot gases forming a stratified layer at the ceiling, the limiting co n fig-I uration would be the highest redundant hot shutdown circuits.

The redundant trains closest to the ceiling are cable trays EC, FR and FV all containing service water pump power as their common element with the lowest tray elevation at 14'10". The smallest i

j quantity of acetone necessary to cause redundant failure of these

,~

trays is 13 3 gallons spilled over a circular area at least 72

- -- y 3

~p 6v> -

3 -* ,

w c...

47 Fire Area 6 .

\"

5 s'

+

A," [q Pa'ge 4-84

, s p

a feet in diameter with the fhilb,re criteri& not' exceeded - fo r

y. '

at least 237 seconds. The model fire >would inv'olv e an acetone pool R

approximately 12 mm deep, a depth aldost'15 : times greater -than b

that expected from -a spillsoAssetouc on a horizontal surface of concrete. \\ ,

s t .

Exposure Fire Effects Model (Area 6)

. A The exposure fire effects of radiNtfon were then modeled- to s justify existing configuration / crN c'enfigurations' including ~~

cer-tain specific modifications. T. h,L ,se pu> pose was'to demonstrate that t

the passive protection provided, by w, tw axisting circuit location',

t plus any proposed modifibations,1 would require' a minimum volume i 4 s. ,

of acetone necessary" fo,r failure s greater i thanithe 13 3 gallons Q

V t

which could cause redundant \ failure due to st,r atification o f h. ot combustion gases. Furtlier podificationsito protect cables from-radiation-induced damage 3Scudd(not be'tequired because the hot gas stratification would causa) Ndundadt fa.il'ur e o f th e , se r v ic e

,, - ; _c ' ' s . ,

water cables as previously'd'esdrLUed. -

'~

Due to the 1arge quant'ity of conduit in Fire Area 6, .a-T ,

bounding calculation $3s4 performed to determi_ne the snecescary a

horizontal separation for bare \ conduit. s' To.be conservative the "s ,. s 4 s t conduit was assumed to 'oe at the sWtchps ca, binet height of 7 5 feet. The fire diameter was not 1.imited even though fr ee floor s': . g i

+

space between cabinet rde is / leo t' han '

6 fedt. ' In the modeling N -.

's i ,

e f fo rt the fire was ass'um.id t6_be placen\> dit*ectiy' between the' .

n- ,

l redundant conduits'even tko' ugh'$hisisnot\ possible' in '

most l ' . ,i' .

j cases. No thermal lag of the conduit was assumed nor was credit

'i e.., .- ,

\N \,  :

.,  % i 1

gas i 4

, .- s ,

• w , , _N

___ _ -- ~ , .

b, - -

l l

47 Fire Area 6 Page 4-85 O taken for the shielding effects of the switchgear cabinets. It was d etermin ed that for redundant conduits 15 feet apart the minimum volume of acetone required for radiation caused failure would be 14.6 gallons, a volume which is larger than the volume

required for stratification failure of the most limiting cables.

The acetone would have to be spilled over a circular area at i least 7 4 feet in diameter with the cable failure criteria not 4

exceeded fo r at least 271 seconds. The model fire would be approximately 13 me deep, a depth almost 17 times greater than that expected from a spill of acetone on a horizontal surface of concrete. The results of this bounding radiation calculation imply that, as long as both divisions are greater than 7 5 feet

[]) from the floor, redundant conduits require only 15 feet of horizontal separation. If this separation does not exist, protec-tion is needed only up to the point where 15 feet of separation is achieved. The redundant trains of conduit along with the proposed modifications resulting from this analysis are sum-marized in Section 4 7 3 Redundant conduits will be wrapped with an appropriate fire barrier until the requisite 15 feet of horizontal separation is achieved.

The various redundant cable trays were analyzed individually for radiation effects due to an exposure fire. There are no Unit 1 cable trays with less than 20 feet of horizontal separation, but there is a single set of Unit 2 redundant trays requiring protection. These are trays ET and EW in Division A and tray 'EK

c. -

l in ' Division B. Physical location of these trays is shown on the

47 Fire Area 6 Page 4-86 g/

(_ Unit 2 sketch in Section 4 7 2. To protect against possible j cable failure due to exposure fire radiation, non-combustible thermal shields will be installed. These shields will- completely enclose redundant divisions until at least 8 fect of horizontal separation is achieved, and after that a shield will be placed beneath both trays EK and ET until 15 feet o f horizontal separa-tion is achieved. By completely enclosing redundant divisions the cables will not be exposed to an external radiant energy flux until the trains are 8 feet apart. With 8 feet of horizontal separation and a thermal shield beneath both trays, the minimum volume of acetone necessary for failure would be 13 6 gallons, a quantity larger than the smallest quantity of acetone necessary for stratification failure of the most limiting cables. The O '

energy shield beneath trays EK and ET will extend out to thermal the point where 15 feet of horizontal separation is achieved.

Appropriate protection will be provided to ensure that other cable trays due not all to the heat load of the initial fi r e .

Further protection past 15 feet is not required as demonstrated in the bounding calculation performed for sections of conduit.

The proposed modifications will be more than adequate because the location of the trays over the switchgear cabinets will not accommodate placement of a fire directly between the trays as was assumed in the analysis.

The remaining contents of Fire Area 6 requiring analysis are

! common plant cable trays. The first of these redundant circuits examined was trays EC and FV. Both trays are 14'10" above the

({])

floor and separated by a horizontal distance of 10 feet. To l

47 Fire Area 6 Page 4-87 fh

,'- protect these cables from redundant failure due to energy deposi-tion from an exposure fire a thermal shield will be placed be-neath redundant divisions until 12 feet of horizontal separation is achieved. With the shields in place, the minimum volume of acetone required to cause failure at the end-to-end separation distance of 10 feet would be at least 21 9 gallons spread over a circular area at least 9 8 feet 19 diameter and 11 mm in depth.

To cause failure of the unprotected cables at a height of 14 feet 10 inches with 12 feet of horizontal separation would require a minimum quantity of acetone of at least 13 9 gallons spread over a circular area of at least 10 7 feet in diameter and to a depth of 6 mm. Because the minimum required volume of acetone for

(} radiation failure is greater than that necessary for str ati fic a-tion failure, the proposed modifications provide adequate prot' c- e tion for the analyzed cable trays. Ther e fo re , any radiation modifications above those proposed would not provide any addi-tional protection.

Redundant trays FH and EH are vertical trays rising out of pull boxes along the east wall. To protect tray EH from damage it will be enclosed along its entire length by a thermal shield protecting all exposed sur faces. The pull box associated with tray EH will be similarly protected.

Red und an t trays GA and GE are vertical trays which run up the north wall. To protect tray GE it will be completely en-closed along its entire length by a thermal shield protecting all O)

(_ ex posed sur faces.

47 Fire Area 6 Page 4-88

() The postulated fire diameter is as important as the minimum volume in specifying the smallest quantity of fuel necessary to achieve the damage criteria. Increasing or decreasing the fir e diameter would necessitate a fire involving greater quantities of acetone in order to provide the same energy flux at the locations of interest. Smaller diameters would require longer-burning fir es with greater fuel depth in order to achieve the same inci-dent energy flux on a cable while larger fires would implicitly necessitate larger quantities o f fuel . These results further demonstrate that for the extremely conservative assumptions uti-lized in these models, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for both divisions under any circumstances irrespective of fire location.

Results and Conclusions The stratific'ation model results demonstrate that contain-ment of the 13 3 gallons of acetone to a depth cf 13 mm. almost 15 times its unconfined spill depth and a 72 foo t diameter-necessary to initiate damage to both divisions is an unrealistic condition. Actual plant storage provisions and operating prac-tices further demonstrate that it would be extremely difficult to accumulate 13 3 gallons of acetone anywhere within the plant, much less at the precise location and in the precise geometry determined by this analysis to be necessary for redundant cable, fail ure .

(~} In reality, the existing configuration can be expected to s-l provide sufficient passive protection against even greater quan-l

47 Fire Area 6 Page 4-89 O tities of acetone with the precise value depending on how realis-tically a "best estimate" analysis is performed . Elements to be included in such realistic analyses could include the response of automatic detectors and of installed manual suppression systems in the area, the value of administrative controls in reducing the likelihood of substantial fuel quantities, and anticipated opera-tor actions relative to achieving safe shutdown while a fire is in progress.

Fire Area 6 relies upon a properly-balanced approach to fir e protection which includes a comprehensive site fir e prevention and combustible material control program, the inherent protection

~

provided passively by the existing configuration, automatic de-() tection, automatic suppression and manual fire fig hting . This balanced approach was developed in response to the Browns Ferry fire and re flec ts the guidance provided by Branch Technical Position APCSB 9 5-1.

The conservative quantitative fire hazards ar.alysis de-scribed herein demonstrates that the addition of the proposed radiant energy shields will protect Fire Area 6 hot shutdown cables from electrical failure resulting from any reasonable l n

exposure fire in compliance with Appendix R, Section III.G. The ceiling stratification model of this analysis demc astrates that Fire Area 6 is adequately protected from the effects of a postu-lated exposure fire regardless of horizontal separation between redundant cables. Fire detection and automatic fire suppressi'on T

(l is provided for Fire Area 6 in compliance with Appendix R, Sec-

- . - _ ~ . - _ _ - - _ _ - . - _ . - . . . . - - . _ ~ . _ _ _ _ . . - . - . _ _ _ . . ~ . _ - . _ . . . _- . . . - - - - _ .

} ,

4 47 Fire Area 6 Page 4-90 i

i O tion 111.0 2. This and other fire protection feetures descrihet in this analysis demenstrate that additional modifications would t

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-not enhance fire protection of the safe shutdown capability.

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4.7 1 Fire Area 6: Evaluation Parameters Page 4-91 O)

(_ Table 4.6-1 FIRE AREA 6: 4160 SWITCHGEAR ROOM EVALUATION PARAMETERS

SUMMARY

A. Area description

1. Constr uc tion

a. Walls North - 8 inch concrete block ; 3-hour-rated fir e seals.

South - 1'-6" concrete ; 3-hour-rated fire seals Ea st - 1'6" concrete; 3-hour-rated fire seals West -

1'-6" concrete; 3-hour-rated fire seals

b. Floor - 10" concrete; basement O c. Ceiling - 10" concrete, 3-hour-rated fire seals

2. Ceiling height - 17'2" 3 Room volume - approx . 30,000 ft 3

4. Ventilation - 3750 CFM 5 Congestion - Access to this area is automatically controlled by the station security system. General access for manual suppression is considered excellent.

B. Fire Hazards Analysis

1. Type of combustibles in area: electrical cable

2. Quantity of combustibles: with the 13 5 lb/ft 2 fixed .

l combustible loading due almost entirely to cable insul-ation.

() 3 Ease of ignition and propagation: Cable is polyvinyl-chloride jacketed with polyethylene insulation; appro-l

471 Fire Area 6: Evaluation Parameters Page 4-92 O priate propagation retardancy is assumed to exist where necessary.

4. Heat release potential:

PE/PVC Cable Heat Relgase Rate

( kW/ M )

convective 228 radiative 131 actual 359 5 Transient combustibles - Essentially n'one; there is no reason for any quantities of flammable liquids within this area.

6. Suppression damage to equipment - Water spray damage potential to the electrical equipment due to manual b suppressior could be significant; however, the single failure proof Halon suppression system will extinguish any area fires so water suppression will not be re-quired.

C. Fire Protection Existing

1. Fire detection systems - smoke detection system; six (6) photoelectric smoke detectors

2. Fire extinguishing systems l a. Automatically actuated single failure proof Halon i

b. Manual 1-1/2-inch water hose reel system

c. Manual portable extinguisher 1

e

471 Fire Area 6: Evaluation Parameters Page 4-93

($) 3 Hose station / extinguisher I a. Distance to hose . stations -

1. 70' on northside

2. 70' east on northside 3 5' west on southside

b. Distance to c.xtinguishers -

1. - 15# D.C. ( B, C) in room

2. 150#D.C. ( A, B, C) in room wheeled l 3 20# D.C. ( B) 10 ft west on south side 4

4. 150#D.C. ( B) 40ft. west on southside wheeled

5. 20# D.C. ( B) 40 ft, west on northside

6. Three (3) 2 5-gallon pressurized water-in room 7 5' west on southside i

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472 Fire Area 6: Drawing and Cable Schedule Page 4-98 O UNIT 1 CABLE TRAYS AND CONDUIT NECESSARY FOR SAFE HOT SHUTDOWN Fire Area 6: 4160V Switchgear Room i

Control Building - E1.8'0" DIVISION A Conduit Cable Scheme No. Purpose 1A05-1 ZA1A58B St a . Se rv . Tr an s . Bkr .1 A52-58 ZA1A58C Sta. Serv.Trans.Bkr.1A52-58 ZA1B16BB St a . Se rv . Tr an s . Bkr .1 B 52-16B 1X13 ZA1A58A Sta . Serv . Tr an s . Bkr .1 A52-5 8 D11-5 ZAD1109A 125 V DC Distrib. Panel,D11 ZAD1111A 125 V DC Distrib . Panel , D11 Cable Tray Cable Scheme No. Purpose k'

1ET03 ZA1A58B Sta. Serv.Trans.Bkr.1A52-58 ZA1A58C Sta. Serv.Trans.Bkr.1A52-58 ZA1B16BB Sta. Serv.Trans.Bkr.1B52-16B 1ET04 ZA1A58B Sta . Serv . Tr an s . Bkr .1 A52-5 8 ZA1A58C St a . Se rv . Tr an s . Bkr .1 A52-5 8 ZA1B16BB Sta. Serv.Trans.Bkr.1B52-16B DIVISION B Conduit Cable Scheme No. Purpose 1X14 ZB1A64A Sta. Serv.Trans.Bkr.1A52-64 D13-5 ZBD1309A 125V DC Dist . Panel, D13 ZBD1311A 125V DC Dist . Panel, D13 Cable Tray Cable Scheme No. Purpose 1EM02 ZB1A64B Sta. Serv.Trans.Bkr 1A52-64 ZB1A64C St a . Serv . Tr an s . Bkr .1 A52-64 ZB1B17BB St a . Se rv . Tr an s . Bkr .1 B52-17B 1EM03 ZB1A64B Sta . Se rv . Tr an s . Bkr .1 A52-64 ZB1A64C St a . Se rv . Tr an s . Bkr .1 A52-64

(~)N ZB1817BB Sta. Serv.Trans.Bkr.1B52-17B

472 Fire Area 6: Drawing and Cable Schedule Page 4-99 n

UNIT 2 CABLE TRAY AND CONDUIT NECESSARY FOR SAFE HOT SHUTDOWN Fire Area 6-4160V Switchgear Room Control Building El.8'0" i

DIVISION A Conduit Cable Scheme No. Purpose 2X13 ZC2A75A Sta. Serv.Tr.Bkr.2A52-75 D11-6 ZCD1110A 125 VDC Dist . Panel, D11 ZCD1112A 125 VDC Dist . Panel, D11 Cable Tray Cable Scheme No. Purpose 2ET03 ZC2A75B St a . Se rv . Tr . Bkr . 2 A52-75 ZC2A75C St a . Se r v . Tr . Bkr . 2A52-75 ZC2B40BC Sta. Serv.Tr.Bkr.2B52-40B 2EWO1,02 ZC2A75B Sta . Serv .Tr .BKR. 2A52-75 '

ZC2A75C St a . Se rv . Tr . Bkr . 2B 52-75 ZC2B40BC Sta. Serv.Tr.Bkr.2852-40B DIVISION B Conduit Cable Scheme No. Purpose 2X14 Z D2A69 A Sta . Serv . Tr . Bkr . 2A52-6 9 D13-6 ZDD1310A 125 V DC Dist . Panel D13 ZDD1312A 125 V DC Dist . Panel D13 Cable Tray Cable Scheme No. Purpose 2EK02 ZD2A69B Sta . Se rv . Tr . Bkr . 2A52-6 9 ZD2A69C Sta. Serv.Tr.Bkr.2A52-69 i ZD2B25BC St a . Se r v . Tr . Bkr . 2B 52-25B 1 2EK03 ZD2A69B St a . Se rv . Tr an s . Bkr . 2A52-69 ZD2A69C St a . Se r v . Tr an s . Bkr . 2A52-69 ZD2B25BC Sta. Serv.Trans.Bkr.2B52-25B i

472 Fire Area 6: Drawing and Cable Schedule Page 4-100 PLANT COMMON CABLE TRAYS AND CONDUIT (v')

NECESSARY FOR SAFE HOT SHUTDOWN Fire Area 6: 4160V Switchgear Room Control Building El. 8'0" DIVISION A Conduit Cable Scheme No. Purpose 1A05-2 ZE1A60C Emer . Gen . Bkr .1 A52-60 ZE1A60D Emer. Gen.Bkr.1A52-60 1A05-3 ZEG0101F Diesel Generator G01 1A05-4 ZEG0101G Diesel Generator G01 1A05-5 ZE1A60D Emer . Gen . Bkr .1 A52-60 ZE2A73D Emer. Gen.Bkr.2A52-73 ZEG0010F Diesel Generator G01

{} 2A05-1 ZE2A73D Emer. Gen.Bkr. 2A52-73 D01-1

• ZED 0106A Main 125V DC Dist . Panel,' D01 D01-2 ZED 0105A Main 125V DC Dist. Panel, D01 D01-3 ZED 0108A Main 125V DC Dist . Panel, D01 i C34-1 ZE1A60E Emer . Gen . Bkr .1 A52-60 ZE2AS-01E Bus 2A05 ZE2A5-01F Bus 2A05 ZE2A73E Emer. Gen.Bkr. 2A52-73 C34-2 ZEG0101D Diesel Generator G01 ZEG0101E Diesel Generator G01 G01-1 ZE1A60A Emer . Gen . Bkr .1 A52-60 G01-2 ZE2A73A Em er . Gen . Bkr . 2A52-73 P32F1 ZE2B34BA SW Pump P32F P32F2 ZE2B34BB SW Pump P32F r"s '

V

472 Fire Area 6: Drawing and Cable Schedule Page 4-101

() Division A-Continued Cable Tray Cable Scheme Nc. Purpose 1EC01 ZE1810CA SW Pump P32A ZE1B10CD SW Pump P32A ZE1811CA SW Pump P32B ZE1B11CD SW Pump P32B 1ET01,02 ZE1A60D Emer. Gen.Bk. 1A52-60 ZE1A60E Emer. Gen.Bkr.1A52-60 ZE2AS-01E Bus 2A05 ZE2A5-01F Bus 2A05 ZE2A73D Emer. Gen.Bkr.2A52-73 ZE2A73E Em er . Ge n . Bkr . 2 A52-7 3 ZEG0101D Diesel Gen.G01 ZEG0101E Diesel Gen.G01 ZEG0101F Diesel Gen. G01 1ET03 ZE1A60C Emer . Gen .Bkr .1 A52-60 ZE1A60D Emer. Gen.Bkr.1A52-60 ZE1A60E Emer . Gen .Bkr .1 A52-60 ZE2AS-01E Bus '2A05 ZE2A5-01F Bus 2A05 ZE2A73E Emer. Gen. Bkr. 2A52-73 O ZEG0101D ZEG0101E Diesel Gen. G01 Diesel Gen . G01 .

ZEG0101F Diesel Gen . G01 1ET04 ZE1A60C Emer . Gen . Bkr .1 A52-60 ZE1A60E Emer . Gen . Bkr .1 A52-60 ZE2AS-01E Bus 2A05 ZE2A5-01F Bus 2A05-ZE2A73E Emer. Gen.Bkr.2A52-73 ZEG0101D Diesel Gen. G01 ZEG0101E Diesel Gen. G01 2ET01 ZE2A73D Emer. Gen.Bkr.2A52-73 2ET03 ZE2A73C Em er . Gen . Bkr . 2A52-73 ZE2A73D Emer. Gen.Bkr.2A52-73 2ET04 ZE2A73C Em e r . Gen . Bkr . 2A52-73 )

ZE2A73D Emer. Gen.Bkr.2A52-73 1EV01 ZE2834BA SW Pump P32F ZE2B34BB SW Pump P32F i l

l 2EWO1,02 ZE2A73C Emer . Gen .Bkr . 2A52-73

()

9

472 Fire Area 6: Drawing and Cable Schedule Page 4-102

() Division A-Continued Cable Tray Cable Scheme No. Purpose FH01 ZE1810CA SW Pump P32A ZE1B10CD SW Pump P32A ZE1811CA SW Pump P32B ZE1B11CD SW Pump P32B FP02,03,04 ZEG0101H Diesel Gen . G01 ZEG0101N Diesel Gen . G01 ZEG0101R Diesel Gen . G01 ZEG0101S Diesel Gen. G01 FUO1,02 ZE2B34BA SW Pump P32F ZE2B34BB SW Pump P32F GA01 ZED 0101A Main 125 V DC Dist. Panel GB01 ZED 0101B Main 125 V DC Dist. Panel GJ01 ZE1A60D Emer. Gen.Bkr.1A52-60 ZE1A60E Emer. Gen.Bkr.1A52-60 ZE2A5-01E Bus 2A05

() ZE2A-01F ZE2A73D Bus 2A05 Emer. Gen.Bkr. 2A52-73 .

ZE2A73E Emer. Gen.Bkr. 2A52-73 ZEG0101D Diesel Gen.G01 ZEG0101E Diesel Gen.G01 ZEG0101F Diesel Gen .G01 ZEG0101H Diesel Gen.G01 ZEG0101N Diesel Gen .G01 ZEG0101R Diesel Gen .G01 ZEG0101S Diesel Gen.G01 DIVISION B t Conduit Cable Scheme No. Purpose 1A06-1 ZFG0201F Diesel Generator G02 1A06-2 ZFG0201F Diesel Generator G02 ZFG0201G Diesel Generator G02 1A06-3 ZFG0201G Diesel Generator G02 1A06-5 ZFIA66D Em er . Gen . 2:r . 1A52-66 ZF1A66E Emer. Gen.Bkr. 1A52-66 D02-1 ZFD0206A Main 125V DC Distribution Pan el , D02

472 Fire Area 6: Drawing and Cable Schedule Page 4-103  :

(~) Division B-Continued Cable Tray Cable Scheme No. Purpose D02-2 ZFD0205A Main 125V DC Distribution Pan el , D02 D02-3 ZFD0208A Main 125V DC Distribution Pan el , D02 C35-1 ZF2A6-01E Bus 2A06 ZF2A6-01F Bus 2A06 C35-1 ZF2A67D Emer. Gen.Bkr.2A52-67 ZF2A67E Emer. Gen.Bkr.2A52-67 ZFG0201D Diesel Generator G02 ZFG0201H Diesel Generator G02 C35-2 ZFG0201N Diesel Generator G02 FV-1 ZFG0201R Diesel Generator G02 ZFG0201S Diesel Generator G02 G02-1 ZF1A66A Dner. Gen.Bkr.1A52-66 G02-2 ZF2A67A O Em er . Gen . Bkr . 2A52-67 k/ 1EM02 ZF1A66C Dner. Gen.Bkr.1A52-66 ..

ZF1A66E Emer. Gen.Bkr.1A52-66 ZFG0201E Diesel Generator G02 1EM03 ZF1A66C Emer . Gen . Bkr .1 A52-66 ZF1A66D Emer. Gen.Bkr.1A52-66 ZF1A66E Emer. Gen.Bkr.1A52-66 1EX01 ZF1B20CA SW Pump P32C ZF1B20CD SW Pump P32C 2EK02 ZF2A6-01E Bus 2A06 ZF2A6-01F Bus 2A06 ZF2A67C Emer . Gen .Bkr . 2A52-67 ZF2A67D Emer. Gen.Bkr. 2A52-67 ZF2A67E Emer . Gen .Bkr . 2A52-67 ZFG0201D Diesel Generator G02 ZFG0201H Diesel Generator G02 ZFG0201N Diesel Generator G02 ZFG0201R Diesel Generator G02 ZFG0201S Diesel Generator G02

(/

l 472 Fire Area 6: Drawing and Cable Schedule Page 4-104

() Division B-Continued Cable Tray Cable Scheme No. Purpose EH01 ZF2B27BA SW Pump P32D ZF2B27BB SW Pump P32D ZF2B27CA SW Pump P32E ZF2B27CB SW Pump P32E FR01,02 ZF1B20CA SW Pump P32C ZF1B20CD SW Pump P32C FV01,02,03 ZF1A66D Emer . Gen . Bkr .1 A52-66 ZF1A66E Emer. Gen.Bkr.1A52-66 ZF2A6-01E Bus 2A06 ZF2A6-01F Bus 2A06 ZF2A67D Emer. Gen. Bkr.2A52-67 ZF2A67E Emer. Gen. Bkr. 2A52-67 ZF2B27BA SW Pump P32D FV01,02,03 ZF2B27BB SW Pump P32D ZF2B27CA SW Pump P32E ZF2B27CB SW Pump P32E ZFG0201D Diesel Generator G02 ZFG0201N Diesel Generator G02 ZFG0201R Diesel Generator G02

() ZFG0201S Diesel Generator G02 GE01 ZFD0201A Main 125V DC Dist. Panel '

GF01 ZFD0201B Main 125V DC Dist. Panel GM01 ZF1A66D Emer. Gen.Bkr.1A52-66 ZF1A66E Emer. Gen.Bkr.1A52-66 ZF2A6-01E Bus 2A06 ZF2A6-01F Bus 2A06 ZF2A67D Emer. Gen.Bkr.2A52-67 ZF2A67E Emer . Gen . Bkr . 2 A52-67 ZFG0201D Diesel Generator G02 ZFG0201F Diesel Generator G02 ZFG0201H Diesel Generator G02 ZFG0201N Diesel Generator G02 ZFG0201R Diesel Generator G02 ZFG0201S Diesel Generator G02 l

473 Fire Area 6: Proposed Specific Modifications Page 4-105

() CABLE TRAY CONDUIT IN FIRE AREA 6 WITH PROPOSED SPECIFIC MODIFICATIONS Division A Division B Resolution Unit 1 Conduit: 1x13 1x14 wrap all of 1x14 in 1hr. barrier D11-5 D13-5 wrap all of D13-5 in 1hr. barrier Unit 2 2x-13 2x-14 wrap 2x-14 in 1 hr.

Conduit: until 15ft of separation D11-6 D13-6 wrap D13-6 in Ihr.

barrier until 15 ft. of separation Unit 2 Cable tray: 2ET03&2EWO1;02 2EK02,03 radiant energy shields:

1) enclose EK until 8 FT of separation 2)beneath EK&ET until

([) 15 FT of separation Common plant conduit: 1A05-3 1A06-1 . wrap all of 1 A0G-1 ,

in 1 hr. barrier 1A05-4 1A06-2 wrap all of 1 A06-2 in 1 hr. barrier D01-1 D02-1 no modifications required greater than 15 ft of separation D01-2 D02-2 no modifications required greater than i 15 ft of seperation D01-3 D02-3 no modifications required greater than 15 ft of seperation G01-1 G02-1 wrap all G02-1 in 1 hr. barrier f'] G01-2 G02-2 wrap all G02-1 hr. barrier in 1 a

4.7 3 Fire Area 6: Proposed Specific Modifications Page 4-106

() Division A Division B Resolution Common Plant Cable tray: 1EC01 FV01-4 radiant energy shields beneath EC until 13 ft of horizontal  ;

separation 2ET01-4 2EK02 same as above for Unit 2 2EWO1,2 EH01 radiant energy shield on all exposed '

surfaces of EH GA01 GE01 radiant energy shield 1 on all exposed j surfaces of GE  :

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4.8 Fire Zone 7 Page 4-107

() 4.8 FIRE ZONE 7: CONTAINMENT SPRAY ADDITIVE TANK AND MONITOR AREA Description Fire Zone 7 is located in the center section (east) of the Auxiliary Building at elevation 26'0". The cable spreading room wall to the east of Fire Zone 7 is a three (3)-hour fire rated concrete wall and the walls to the north and south are at least 18-inch-thick concrete non-fire rated. There is an open floor area to the west extending approximately 60 feet with an open hatch and stairway in both the floor and ceiling. Eig ht-foo t high open archways provide access to the zones to the nortn and south. The riser trays along the east wall penetrate the floor

_, through three-hour-rated fire seals behind a 6" hig h concrete

\~) curb that extends 3'6" out from the east wall. The height , of the ceiling is 18'6". Pertinent room dimensional data are con-tained in Table 4.8-1 Evaluation Parameters Summary and Figures 4.8-1 and 4.8-2.

Fire Zone 7 contains the following equipment: containment spray additive tanks, boric acid filters, boric acid transfer and recirculation pumps, and the boric acid heat tracing transformers and recorder racks. Also present are the non-sa fe t y-rel ated chemical and volume control system monitor tanks and pumps, and the boron recycle and waste disposal system control panels.

Safety-related 480v motor control cabinets 1842 and 2B42 are also present. None of the equipment present in this zone is required

()

for sa fe shutdo wn . The four boric acid tr an s fer pumps are aligned in a row with centerlines three feet apart; however, l

4.8 Fire Zone 7 Page 4-108 O'~'

these pumps are canned type and contain no lubricating oil. The only hot shutdown circuits of concern are those cables required for charging pump operation and pressurizer heater power.

The fixed combustible loading within this zone is due almost entirely to the cable density and results in a fire loading of approximately 4.5 lb./ ft2 This area has been classified as C-i moderately severe according to NFPA standards and the expected fire duration of an uncontrolled , f ull y-d ev eloped fire is 35 minutes, which correlates to an equivalent fire severity of 25 minutes. Controlled quantities of transient combustible mate-rial are expected to be transported through the immediate vicini-ty but not stored or accumulated in this zone. The floor space

(]) immediately in front of the curb along the east wall is the only clear aisle space between the north and south wings of the ux-iliary Building. The necessary aisle passage practically elimi-nates the potential for accumulation of any material in this space. A controlled amount of combustible material in the form of drawings and notepads is necessary at the Auxiliary Building operator station located in this fire zone.

Fire Zone 7 is provided with seventeen (17) photoelectric smoke detectors suitably located throughout the zone which alarm individually at a local alarm panel, subsequently providing a i

common fire zone alarm in the control room. Four manual one-and-one-half (1-1/2)-inch hose reel stations are located immediatel y-north of, south of, and at the west side of the zone. Each area O

\/ of the zone is capable of being covered by a hose stream from at I ,

4.8 Fire Zone 7 Page 4-109

("s least two hose reel stations.

V Exposure Fire Effects Model (Zone 7-Pre-Modification)

The exposure fire effects of convection and str ati fic ation were first modeled to determine the degree of passive protection provided by the existing configuration for Fire Zone 7 In this model, horizontal separation is of no consequence and the fire zone ceiling and cable tray heights are the important parameters.

The limiting configuration for stratification is the two highest redundant cable trays. For Fire Zone 7, this was trays FL and FJ containing Unit 1 Pressurizer Heater power cables with tray FL penetrating the ceiling height and tray FJ at a height of 16'6".

The smallest quantity of acetone necessary for failure would be

) 14 5 gallons spilled over a circular area at least 7.6 feet .in diameter with the failure criteria not exceeded for at least 243 seconds. The model fire would involve an acetone pool approx-imately 12 mm deep, which is a depth almost fi fteen (15) times greater than that expected from a spill of acetone on a horizon-tal surface of concrete.

Exposure Fire Effects Model (Zone 7-with Modifications Prior to modeling the effects of radiation from an exposure fir e , certain specific modifications were proposed for fire zone 7 cable trays FL, CN, CK, and FX will have radiant energy shields installed on all exposed surfaces. Only the east sides of J

s the trays facing the east wall will not require any protec-tion.

These shields will assure that at least one train of safe i

4.8 Fire Zone 7 Page 4-110 O

shutdown cables for each Unit will not experience failure due to the radiation effects from an exposure fire.

The postulated fire diameter is as important as the volume in this model. Increasing or decreasing the fire diameter would necessitate greater quantities of acetone in order to exceed the cable failure criteria. Smaller diameters would require longer-burning fir es with greater fuel depth in order to achieve the optimum combination of heat and energy fluxes while larger fires would implicitly necessitate larger quantities of fuel. These results further demonstrate that fo r the extremely limiting assumptions utilized in this model, it is not possible for lesser quantities of acetone to exceed the cable damage criteria for

(]) both divisions under any circumstances irrespective of fire loca-tion.

Results and Conclusions The stratification model results demonstrate that contain-ment of the 14 5 gallons of acetone necessary to initiate failure in both divisions to almost 15 times its unconfined spill depth without exceeding 12 mm of depth with a minimum 7 6 foot diameter is an unrealistic condition. Actual plant storage provisions and operating practices further demonstrate that it would be extreme-ly difficult to accumulate 14.5 gallons of acetone anywhere within the plant much less at the precise location and in the -

precise geometry determined by this analysis to be necessary fo r O-- redundant cable failure. -

4.8 Fire Zone 7 Page 4-111

() In reality, the existing configuration can be expected to provide sufficient passive protection against even greater quan-tities of acetone with the ' precise value depending on how realis-tically a "best estimate" analysis is per formed . Elements to be included in such realistic analyses might include the response of automatic detectors and of installed manual suppression systems in the area, the value of ' administrative controls in reducing the likelihood of substantial fuel quantities, and anticipated opera-tor actions relative to achieving safe shutdown while a fire is in progress.

Fire Zone 7 relies upon a properly balanced approach to fire protection which includes a comprehensive site fir e prevention 7, and combustible material control program, the inherent protection

(.) provided passively by the existing configuration, automatic de-tection, and manual fire fighting. This balanced approach was developed in response to the Browns Ferry fire and reflects the guidance provided by Branch Technical Position APCSB 9 5-1.

The conservative quantitative fire hazards analysis de-scribed herein demonstrates that the addition of the proposed modifications will protect Fire Area 7 hot shutdown cables from electrical failure from any reasonable exposure fire in compli-ance with Appendix R Section III.G. The ceiling stratification model of this analysis detaonstrates that Fire Area 7 is adequate-

,, ly protected from the effects of a postulated reasonable exposure fir e regardless of horizontal separation between redundant cab-(m) les. The moderate combustible loading of Fire Area 7 together with fire protection. features described in this analysis demon-

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4.8.1 Fire Zone 7: Evaluation Parameters Page 4-113

) Table 4.8-1 )

FIRE ZONE 7: CONTAINMENT SPRAY ADDITIVE TANK AND MONITOR TANK ROOM EVALUATION PARAMETERS

SUMMARY

A. Area description

1. Construction

a. Walls fiorth -2'0"-inch concrete South -2'0"-inch concrete East - 2'0"-inch concrete West - 3'6"-inch concrete

b. Floor -1'6"-inch concrete 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated fire seals O for combustible pathways ,

c. Ceiling -1'6"-inch concrete 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> rated fire seal for combustible pathways

2. Ceiling height .18'6" 3 Room volume - dependent on width of room used in analy-sis

4. Ventilation - 8500 CFM 5 Congestion - Access to east wall area is generally good B. Safe Shutdown Equipment

1. Redundant systems in area

a. Division A: circuits as listed in Section 4.8.2

b. Division B: circuits as listed in Section 4.8.2 C) v

4.8.1 Fire Zone 7: Evaluation Paraaeters Page 4-114

2. Equipment in area is not required fo r shutd o wn .

(]} hot The postulated exposure fire is asssumed to be con-tained within north, south and east walls.

C. Fire Hazards Analysis

1. Type of combustibles in area: electrical cable

2. Quantity of combustibles: the area generally contains very low quantities of combustible material end the 4 5 lb/ft 2 fire loading is almost entirely due to electri-  :

l cal cable <

i 3 Ease of ignition and propagation: cable is pol yv in yl-chloride jacketed with polyethylene insulation; cable is flame retardant and resists propagation

4. Heat release potential:

(} a. PE/PVC cable Heat Release d Rate'

( kW/ M i

convective 228 radiative 131 actual 359 5 Transient combustibles - Essentially none; only limited quantities (less than one (1) pint) of acetone used in welding stainless steel.

6. Suppression damage to equipment - Water spray damage potential to the equipment due to manual suppression is negligible to the confined area which is separated from other. sa fety-related equipment .

\

4.8.1 Fire Zone 7: Evaluation Parameters Page 4-115 D. Fire Protection Existing

1. Fire detection systems - smoke deteation systems; seventeen (17) photoelectric smoke detectors

2. Fire extinguishing systems i a. Manual 1-1/2-inch hose reel stations i b. Manual portable extinguishers 3 Hose station / extinguisher a.. Distance to hose stations

1) 5 ft north

2) 5 ft south

3) in zone

4) in zone

b. Distance to extinguishers

1) 20#D.C. ( A, B, C) in zone

2) 20#D.C. ( A, B, C) 40ft. north

3) 10#D.C. ( A, B, C) Sft. south

([) 4) 20#D.C. ( A, B, C) 50ft. west i

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4.8.2 Fire Zone 7: Drawing and Cable Schedule Page 4-118 UNIT 1 CABLE TRAYS AND CONDUIT NECESARY FOR HOT SAFE SHUTDOWN Fire Area 7: Monitor T0!k Room Auxiliary Building, El. 26'0" DIVISION A Conduit Cable Scheme No. Purpose PP13 1B12BA Pressurizer Heater, "roup C Cable Tray Cable Scheme No. Purpose I

CS02 ZA1813AC CVCS Charging Pump 1P2A ZA1813BC CVCS Charging Pump 1P2B FJ04 1B12BA Pressurizer Heater, Group C JD01 ZA1B13AC CVCS Charging Pump 1P2A O ZA1B13BC CVCS Charging Pump 1P2B ,

DIVISION B ,

Conduit Cable Scheme No. Purpose  :

PP14 1B21BA Pressurizer Heater, Group D Cable Tray Cable Scheme No. Purpose CNO3 ZB1820AC CVCS Charging Pump 1P2C FLO2 1B21BA Pressurizer Heater , Group D 1B22CA Pressurizer Heater, Group E i  ;

i 1

l 1

4.8.2 Fire Zone 7: Drawing and Cable Schedule Page 4-119

{} UNIT 2 CABLE TRAYS AND CONDUIT NECESSARY FOR HOT SAFE SHUTDOWN Fire Area 7: Monitor Tank Room Auxiliary Building, El. 26'0" DIVISION A Conduit Cable Scheme No. Purpose PP19 2B36BA Pressurizer Heater , Group "C" Cable Tray Cable Scheme No. Purpose CK01 ZC2B37AC CVCS Charging Pump 2P2A ZC2B37AF CVCS Charging Pump 2P2A ZC2B37BC CVCS Charging Pump 2P2B ZC2837BF CVCS Charging Pump 2P2B FT03 2B36BA Pressurizer Heater, Group C t'

V) '

DIVISION B Conduit Cable Scheme No. Purpose PP18 2B29BA Pressurizer Heater, Group D Cable Tray Cable Scheme No. Purpose CF03 ZD2B28AA CVCS Charging Pump 2P2C -

ZD2B28AC CVCS Charging Pump 2P2C ZD2B28AF CVCS Charging Pump 2P2C CG03 ZD2B28AA CVCS Charging Pump 2P2C ZD2B28AF CVCS Charging Pump 2P2C '

FXO4 2B29BA Pressurizer Heater, Group D 2B30CA Pressurizer Heater , Group E k

u-) .

e

49 Fire Protectior. From Hydrogen Hazard Page 4-120 4.9 Fire Protection from Hydrogen Hazard An open item from the 1977 fire hazards analysis per formed in accordance with Branch Technical position APCSB 9 5-1 Appendix A was that of protection against a postulated hydrogen header break and ignition in general areas. Despite the high flame temperature of a hydrogen burn, such a fire fails to produce soot and is not expecially luminous making detection of this postulated fire by the existing fire detection system a difficult process. Re fl ec tins this situation passive protection was analyzed and no credit taken for fire brigade response.

In analyzing the effects of such a fire, a hydrogen leak rate was postulated at more than double the leak rate which c~ould

(~T occur undetected anywhere in the plant. This leak rate was then

'V postulated to be in the fire zone with the worst case configu'r a-tion for ceiling stratification. In this case the event was not considered to be realistic because the hydrogen piping in ques-tion does not run through the designated fire zone. The focus o f the analysis was to determine whether the heat flux produced by ceiling stratification of hot gases and water vapor would produce a situation where redundant safe shutdown circuits would experi-ence failure.

Comparison of the hydrogen analysis results with the postu-lated acetone fire effects resulted in the acetone fire being the most severe event. On this basis it is concluded that the hazards of hydrogen fires are bounded by those associated with  ;

("%

(_) liquid hydrocarbon spills and the proposed mod ific ations which

l 49 Fire Protection From Hydrogen Hazard Page 4-121 O provide eae9uete protectioa to reauaaeat not sautaowa circuite from liquid hydorcarbon fires also protects these same circuits from hydrogen fire damage.

O ..

4. Analytical Methods Page 4-122 i

O References l I

(1) Special Review Group, " Recommendations Related to Browns Ferry Fire", NUREG-0050, U.S. Nuclear Regulatory Commission ,

Washington, DC, February, 1976.

(2) NRC, " Guidelines for Fire Protection for Nuclear Power Plants", Auxiliary Systems Branch Technical Position 9 5-1, Revision 1, U.S. Nuclear Regulatory Commission, Washington, DC, November 1977 (3) NRC, " Fire Protection Guidelines for Nuclear Power Plants",

(For Comment), Regulatory Guide 1.120, Revision 1, U.S.

Nuclear Regulatory Commission , Washington, DC, November, 1977 (4) NRC, " Physical Independence of Electric Systems", Regulatory Guide 1 75, Revision 1, U.S. Nuclear Regulatory Commission ,

Washington, DC, January, 1975.

(5) NRC, " Fire Protection Program for Operating Nuclear Power Plants", 10CFR Part 50, U.S. Nuclear Regulatory Commission ,

45FR76611, November 19, 1980, corrected 45FR79409, December 1, 1980, U.S. Nuclear Regulatory Commis' ion , Washington , DC.

() (6) NFPA, " Fire Protection for Nuclear Power Plants", NFPA-803-1978, National Fire Protection Association, Boston, MA, June 6, 1978.

(7) T.Z. Harmathy, " Relationship Between Fire Resistance and Fire Tolerance", Fire and Materials, V2, N4 (1978).

(8) T.Z. Harmathy and T.T. Lie , " Fire Test Standard in the Light of Fire Research", Fire Test Performance, ASTM STP464, American Society for Te'sETng and Materials (197UT--

(9) T.Z. Harmathy, "The Possibility of Characterizing the Severity of Fires by a Single Parameter", Fire and Materials, V4, N2 (1980).

(10) A. Tewarson, " Ex perimental Evaluation of Flammability Parameters of Pol ymeric Materials", FMRC J. 1.1A6R1, Prepared for Products Research Committee, National Bureau of Standards by Factory Mutual Research Corporation under Grant RP-75-1-33A, Norwood , MA, February, 1979.,

(11) A. Tewarson,. J.L. Lee, and R.F. Pion, "The Influence of Oxygen Concentration on Fuel Parameters for Fire Modeling",

Eighteenth Symposium (International) on Combustion, The Combustion Institute , 1981.

~

3. Analytical Methods Page 4-123 r

O (12) A. Tewarson and R.F. Pion, " A Laboratory Scale Test Method for the Measurement of Flammability Parameters", FMRC No .

22524, Prepared for Products Research Committee by Factory Mutual Research Corporation under Grant No. RP-75-1-33A, Norwood , MA, October, 1977 (13) A. Tewarson, J.L. Lee, and R.F. Pion , " Categorization of Cable Flammability Part 1: Laboratory Evaluation of Cable Flammability Parameters", NP-1200, Part 1, Electric Power Research Institute , Palo Alto , CA, October, 1979 (14) M.A. Delichatsios, " Categorization of Cable Flammability Detection of Smoldering and Flaming Cable Fires", NP-1630, Electric Power Research Institute , Palo Alto, CA, November ,

1980. ,

(15) J.S. Newman and J.P. Hill, " Assessment of Exposure Fire Hazards to Cable Trays", HP-1675, Electric Power Research Institute, January, 1981.

(16) A.T. Modak, "Ignitability of High Fire Point Liquid Spills",

NP-1731, Electric Power Research Institute , Palo Alto, CA, March, 1981.

"s (17) J.L. Lee, " A Study of Damageability of Electrical Cables in

( Simulated Fire Environments", NP-1767, Elec tric Power Research Institute , Palo Alto , CA, March, 1981.

(18) A. Tewarson, " Fire Hazard Evaluation of Mine Materials",

Technical Report RC80-T-77, Factory Mutual Research Corpora-tion, Norwood, MA, October, 1980. ,

(19) J.L. Boccio , " Requirements for Establishing Detector Siting Criteria in Fires Involving Electrical Cable Materials",

BNL-29939, Department of Nuclear Engin eering , Brookhaven National Laboratory, Upton, NY, May, 1981.

(20) Memorandum from Saul Levine , Director, Office of Nuclear Regulatory Research to Robert B. Minogue, Director, Office of Standards Development, and H.R. Denton, Director, Office of Nuclear Re ac to r Regulation,

Subject:

"Research Information Letter #46, ' Effectiveness of Cable Tray- Coating Materials and Barriers in Retarding the Combustion of Cable Trays Subjected to Exposure Fires and in Preventing Propagation between Cable Trays (Horizontal Open Space Con-figuration)'", November 9, 1978.

O

(\sJ

() APPENDIX A Basis for Heat Release Rates This appendix provides the basis for the fuel heat release rates utilized in fire models described in this analysis. The quantities reported herein and the underlying concepts are from the' combustion literature and reflect the current state of know-ledge in the fire sciences. In areas of uncertainty, conserva-tive assumptions are made so as to ensure that the integrity of the analytical method is maintained.

The heat release rate associated with a fire is related to

. the fuel's mass loss rate (pyrolysis) and the heat of combustion 3

- [ Tewarson (1)] by the following relationship:

I

.n QT* *b HT i .n where QT= t tal theoretical heat. release rate m = mass loss rate in burning H

T= _ total theoretical heat of combustion i

!O

- , . - 4 -s- +,,-.m.-, , e

Appendix A, Basis for lleat Release Rates A-2

( The mass loss rate itself is a variable which in a realistic sense is dependent upon multiple factors such as fire stage, gaseous temperature and fuel type. In general, the mass loss rate may be described by the net heat flux delivered to the fuel's surface and its heat of gasification.

.n

." 9n "b

• g where q" = net heat flux received by the fuel O L = heat required to generate '

a unit mass of fuel vapors The dependency of the mass loss rate on the net heat flux delivered to the fuel surface and the associated feedback effects illustrates the historical difficulty of analysts to derive a meaning ful and precise model of flame behavior. The net heat flux itself represents a heat balance at the fuel surface and is given as .the difference between the total heat flux receis ud by

() ~

the fuel and that flux lost through a variety of processes. This balance under steady state conditions may be modified , however,

i Appendix A, Basis for Heat Release Rates A-3

() by such factors as the relative concentration of oxygen entrained in the combustion zone, the externally applied heat flux and the optical path length of the gases. The principal effect of these considerations becomes evident in the actual heat of combustion which reflects different oxidation reactions.

At a detailed level these multiple parameters are all inter-i related. Howev er , it is possible to select a single parameter 1 fo r the purpose of illustrating the sensitivity of the heat release rate to its variation. That single parameter would be the fraction of stoichiometric oxygen to fuel ratio given by:

!' A"o (a)

O =

• b"Ko 2 -

l i

where D = fraction of stoichiometric oxygen to fuel ratio a = fraction of oxygen entrained in combustion K

g

= stoichiometric mass oxygen 2 to fuel ratio -

.n Mg = mass flow rate of oxygen to 2 fire vicinity O

~ - - - - , - - - ,w - - , - s =

Appendix A, Basis for Heat Release Rates A-4 O The effect of variation of this parameter on combustion may be illustrated for the case of pol ymethylmethac rylate over a range of values of the stoichiometric oxygen / fuel fraction:

Fuel Chemical Combustion HA D Condition Reactions Efficiency (kJ/g)

(

I

> 1. 0 Lean CH0 38 2 + 602+ 5C0 2 + 4H2O 100 24.9  !

I i

0.81 Lean CH0 s3 2 + 4.90 2 + 4CO 2 + 35H2O 80 19.9 0.63 Rich CH0 3 g 2

+ 3.80 2 + 4C0 2 + 3.5H 2O 60 14.9

+ 0.25C0 2 + 0.25CH g + 0.75C

(]} -

0.42 Rich C3 H8 0, + 2.50 2 + 200 2 + 2H 2O 35 8.7

+ CO & CH g +C As may be evident from this table, oxygen and combustion efficiency have a significant effect on the overall heat release rate. Moreover, it should be noted that lower combustion effi-ciencies produce increasing amounts of carbon which lead to higher smoke-rates, lower optical transmission path lengths, and

'() higher soot concentrations, thereby reducing even further the effect of the released heat on a target material.

I Appendix A, Basis for Heat Release Rates A-5 O

The stoichiometric oxygen / fuel fraction affects heat release rates through its influence on the value of X, in the standard 1

equation:

.., H,7 )

Qi=Xi (@) i,,n L

where X fraction of total theoretical heat I = release rate associated with mode i This equation and the in fluence o f X on its results is the fundamental relationship for bounding the rate energy is released r~ in a fire. The remainder o f this appendix will focus on each of V;

the following three elements in developing an appropriate rate-for the fuels used in this analysis:

(1) X.

1 fraction of energy released in mode i 9n (2) m b= -

fuel mass loss rate L

(3) H A

ctual heat of combustion

-The objective of the discussion will be to provide a scientific

() basis for selecting bounding values fo r each parameter in

, subsequent analyses.

i Appendix A, Basis for Heat Release Rates A-6

'( ) The close relationship between parameters and the associated feedback effects was presented earlier in this appendix where the inherent difficulties in precisely modeling fir es was demonstrated. Ideally, if bounding values for X i ,

mb and HA could be selected, then one may be assured that the heat release rate is adequately bound through the assumption of a suitably intense fire. ' In order to achieve this goal, it is important to l

relate the three parameters of interest to experimental data and i

sensitivities. Fo r the purpose of illustrating a general con-l l cept, the case of acetone will be discussed beginning with the l

mass loss rate. <

The mass loss rate for a liquid hydrocarbon was previously

() given by: ,,

mb L [from Tewarson (1)]

where q...

n *9 e +9fr + 9fc + 9o -91 4" = external heat flux incident on the fuel q# = flame radiative heat flux incident on the fuel 4"c = flame the fuel convective heat flux incident on I

q = other heat flux incident on the fuel

() q" = heat flux' lost

--w,- ,e--. e- ---, - ~ , -

--- -,,,,,,e , - ,

Appendix A, Basis for Heat Release Rates A-7 0 ... .. .. ..

For small fires, qfc >" kr f while for larger fires, qfp >> qfc where turbulent effects are dominant.

In the region where radiative heat flux to the fuel's sur-face is signi fic ant , it has been found on the basis of ex perimentation that all important parameters are independent of ox ygen concentratioJi [Tewarson (4)]. The affected parameters include:

(1) Those parameters with slight oxygen dependency Actual heat of combustion (HA )

2 - CO 2 yield (YCO2)

(2) Those parameters which decrease with increasing oxygen concentration O -

coaveotive neat or oombustioa caC )

- Convective heat flux incident on the fuel (dhc)

CO yield (YCO)

- Optical path length - fuel vapor concentration ratio (3) Those parameters which increase with increasing oxygen

' concentration l Radiative heat of combustion (HR )

- Fuel vaporization rate (inh)

- Radiative heat flux incident on the fuel (k p)

From this important result, it is apparent that if a conservative ,

assumption is made for ventilation, i.e., that ideal fuel-oxygen ratios above a minimum value (> 5 mole fraction 02) is always .

postulated to exist, then it is possible to bound the value for a liquid hydrocarbon's heat release rate. Further, one also I

Appendix A, Basis fo r Heat Release Rates A-8 O obteins esymptotic ve1ues ror the fue1 steedy stete mess 10ss rate as a function of fire area and the associated heats of combustion (radiative, convective and actual). From this result the remaining parameter is the value of X i. The method of determination for this parameter will be illustrated for the case of acetone, although the nature of the selected hydrocarbon is unimportant.

It has been shown experimentally that the mass loss rate for most liquid hydrocarbons approaches an asymptotic limit at higher rates of 4" [Tewarson (4)], especially for aromatic , i.e., ben-zene-like compounds [Tewarson (3)]. In particular, Te war so n (1) demonstrated that acetone, an aliphatic ketone, exhibits charac-teristics similar to such aromatic liquids which suggests the validity of the asymptotic limit assumption for its fuel vapori.

zation rate. This characteristic limit appears to' be related to the maintenance of a constant q" ratio as sur fac e radiation achieves a dominant role in fuel vaporization. For most hydro-carbons, this limit is bounded by vaporization rates of 40g/m 2 -s, a mass flux supported by experimental data by Tewarson ( 3, 5),

where a value of 30g/m 2 -s is suggested , and by Blinov and Khudia-kov (7). The steady-state fuel vaporization rate used in this analysis is 40 g/m 2 -s.

With this parameter in mind, it is necessary at this point to focus on the heat of combustion associated with the fuel; in this case, acetone. Using a bomb calorimeter which accounts for O 1aea11zea neat measure = eat resu1tias rrom tote 1 mo1eeuter aisso-ciation, Weast (2) reports a theoretical heat of combustion (HT )

Appendix A, Basis for Heat Release Rates A-9 of 426.8 kG-cal /GMW or 30.8 kJ/g. Turning to the experimental literature for the purpose of obtaining a value of xA, Tewarson (2) reports a value of H /L=36 for acetone while Tewarson AT (1) reports HT /L=47 48 This suggests that XA has a laboratory value of 0 76. On this basis, the following heats of combustion may be calculated :

Actual Heat o f Combustion : 23 4 kJ/g Theoretical Heat of Combustion: 30.8 kJ/g These calculated values may be compared to experimental data obtained by Tewarson (6) for acetone:

Actual Heat of Combustion: 21 71 kJ/g Theoretical Heat of Combustion: 28.49 kJ/g .

Recognizing the relatively consistent values obtained under dif-ferent circumstances and assumptions, this analysis utilizes the 4

higher heats of combustion for purposes of conservatism.

It should be noted at this point that Tewarson (6) also reports the following data for acetone in the experiments per-formed :

Actual Heat Release Ra te : 262 kW/m2 actual = 0 762 convective = 0 5666 radiative t( ) luminous = 0.20 highly luminous = 0 37 t

Appendix A, Basis for Heat Release Rat..es A-10

() i It is apparent from a review of this data that a fuel vaporiza-tion rate for acetone of 12.1 g/m2 was characteristi,c of the tests repo ted in Tewarson (6). This vaporization rate may be best described as non-turbulent or transitory, a condition which would be expected to occur at lower oxygen concentrations where i flame convection is the dominant mechanism for fuel vaporization.

In Jarger fires where flow is truly turbulent, it has been seen

[Tewarson (4)] that radiation begins to dominate convective heat release. Utilizing the higher value of 37% for the radiative component associated with highly luminous fl am e s , the following values are assumed for acetone :

{) actual = 0 76 radiative = 0 37 - -

convective = 0 39 This yields the following results for acetone:

Heat of Combustion (kJ/g) convective = 12.0 kJ/g radiative = 11.4 actual = 23 4 complete combustion = 30.8 Vaporization Rate (g/m 2-sec.)

! highly luminous flame = 40.0 l

(

l

i Appendix A, Basis for Heat Release Rates A-11

, () Heat Release Rate (kW/m2)  ;

convective = 480.0 radiative = 456.0 actual = 936.0 In a similar fashion , one may obtain heat release rate data for other fuels. For lubricating oil, Tewarson (4) reports the following data as representative for typical high-temperature hydrocarbons:

Laboratory Large Scale Scale j l

Heat of Combustion (kJ/g) ,

l convective 18.2 -  !

radiative 20.4 16 3 "

actual 38.6 -

complete combustion 46 3 -

T Vaporization Rate (g/m 2_3) highly luminous flame 40.0 26.8 ,

Laboratory Large Scale Scale l Heat Release Rate ( kW/m2) l i

convective 728 534 I l

radiative 816 415 I actual 1544 949 l

Appendix A, Basis for Heat Release Rates A-12 O

(/

Tewarson (4) reports the following data for heptane:

Laboratory Large Scale Scale Heat of Combustion (kJ/g) convective 21.6 -

radiative 17 4 14.4 actual 39 0 -

complete combustion 44.6 -

Vaporization Rate (g/m 2_3) highly luminous flame 70 70.1 Heat Release Rate ( kW/m2) convective 1512 1514

() (estimated)

{ radiative 1218 1009 (estimated) actual 2730 2523 (estimt'.ed)

This analysis utilizes the laboratory scale turbulent values fo r fuel vaporization rate and heat release rates in calculating the e f fec ts of exposure fires on electrical cables and plant equipment. The impact of this practice is that this effectively 4

assumes that the most efficient combustion achievable in the laboratory occurs in general plant areas as well.

h

Appendix A, Basis for Heat Release Rates A-13 A

V

References:

(1) A. Tewarson, " He at Release Rate in Fires", Fire and Materials, V4, pp. 185-191 (1980).

(2) R.C. Weast, Ed i to r , " Hand boo k of Chemistry and Physics",

61st Edition (1980-81), Chemical Rubber Com pan y , Cleveland, 1 OH, 1980.

(3) A. Tewarson, "Physico-Chemical and Combustion / Pyrolysis of Pol ymeric Materials", Report RC80-T-9, Prepared for U.S.

Department o f Commerce , National Bureau of Standards, Center for Fire Research by Factory Mutual Research Co r po r ation ,

Norwood, MA, November, 1980.

(4) A. Tewarson, " Fire Behavior of Transformer Dielectric Insu-lating Fluids" , DOT-TSC-1703, Prepared fo r U . S . Department of Transportation , Transportation Systems Center by Factory Mutual Research Corporation , Norwood, MA, September, 1979 1

(5) A. Tewarson and R.F. Pion, " A Laboratory-Scale Test Method for the Measurement of Flammability Parameters", FMRC 22524, Factory Mutual Research Corporation , Norwood, MA, October,

(]e) 1977 (6) A. Tewarson, " Ex pe r im en tal Evaluation of Flammab ilit y' Parameters of Polymeric Materials", Report FMRC J.1.1A6R1, Prepared for Products Research Committee , National Bureau of Standards by Factory Mutual Research Corporation , February, 1979 (7) V.I. Blinov and G.N. Khudiakov, "Di f fusion Burning of Liquids", Moscow Academy of Sciences (1961) .

I'l

\m/

4

("#

APPENDIX B Stratification The str ati fic ation model used in this section has its origins in work performed by J.S. Newman and J . P. Hill of Factory Mutuel Research Co rpo ration on behalf of the Electric Power Research Institute (1). This EPRI research related the radiative and convective heat flux associated with stratified layers of hot gases developed in an enclosure fire to the room's dimensions, the height above the floor, the fuel's flammability parameters and the ventilation rate. Data was obtained in a series of experiments involving 14 methanol and heptane enclosure fires at elevations ranging from 30%-98% of the ceiling height for up to (V-)

12 room air changes per hour. Among the general observations, FMRC scientists noted the following :

(1) Varying the location of the pan fir e within the enclosure had no appreciable effect on the measured heat fluxes or gas temperatures at any given position.

This suggests the lack of sensitivity of strati fied heat flux to horizontal separation.

(2) Differences in gas temperature or heat flux measurements at the same vertical position at different locations were, in general, inconsequential and within the variation expected from the measuring instrument.

(3) In terms of horizontal variation, measurements indicate a tendency for the enclosure corners to be slightly cooler and receive lower total heat fluxes than at other locations within the enclosure.

(4) The ventilation rate does not appear to have a dominant e f fec t on gas temperatures or heat flux es within the

. enclosure, with ventilation rates below approximately'

_) one and one-half room changes per hour having virtually no effect.

Appendix B, Strati fic ation B-2 O)

(_ (5) The total heat flux measured at any point in the enclosure is approximately 5-10% radiative and 90-95%

convective for all conditions investigated independent of fuel. Since the heat flux data collected was for an expored sphere, this suggests predicted values which would actually be conservative for cylindrical cable bundles found in cable trays.

(6) Because of the observed stratification, the application of these empirical results would be appropriate for any room shape as long as the floor area of the particular room is greater than or equal to the floor area of a comparable room of the same height with dimensions of 2:1:1.

Newman and Hill reported empirical spatially dependent transient and steady state heat fluxes. Figure B-1 illustrates the course of heat flux over time following ignition. The transient heat flux was shown to be related to a time constant gs unique to each fuel that was obtained by a power curve fit to the O fire diameter. Heskestad (2) provides the basis for such a, i

response in the early stages of a fire.

Co r relations of the data were obtained by Newman and Hill (1) and are reproduced below:

2 (1) 4sH h -8 h*73 f

[3p ] = 0.24 - y (Steady State) 9t 13V (2) [-h ]-% = [0.52 + f ] [ ,t ] 0 . 9 (Transient)

H r

q H V2 ss

/ /

Appendix B, Strati fic a tion -- B-3 These results were reviewed for accuracy against the origi-nal data in the EPRI report presented in Table 3-4 of Newman and Hill (1), wnich is reproduced as Tabl e B-1. Plotting the reported data onto Newman and Hill's Figure 3-2 (reproduced herein as Figure B-2) suggests.that the original EPRI correlation defines a poorly behaved function with respect to the ventilation component such that with higher ventilation rates, a refrigera-tion effect may be noted. In reality, while higher ventilation rates will in general have a disruptive effect on any enclosure fire to the point where some mitigation is possible, it was felt that use of the EPRI correlations would be non-conservative at

_ some points. It should be noted, however, that for relatively small exposure fires which are not ventilation-limited , the fire severity is reduced as ventilation increases. This point is discussed in some detail by T.Z. Harmathy (2,3).

Nevertheless, to provide assurance that the function remains well behaved in a conservative fashion and that the experimental data provides bounding results, a mod i fied correlation was obtained as follows :

0.7854k"T 0.05585 0.01031 -0.153),

h

[0.01161 - .h_ f,3 '

g 2 [ (1,193 _ T))2' ( 2.13 H

i f 1H /2 [0.01161 - 0.01031(2.13 - h) 2)

(3) 6 ", = < .

V 0.78546 T gj2 [ __

0.05585 ,

7 f

2 .5 j-0.153.

(1.193 h H g ) Y2 hp 2. H 5/2[0.01161 - 0.01031(2.13 - ) ']

s J

1 Appendix B, Stratification B-4 ,

,l O 13V p i

." ... t , , , , , ,

l (4) qt=qss ( r) 0 . 9 [ Hh ) %' [ 0 . 5 25/2

+ J ; qt<qss '

l H

1 .;

Utilizing these revised correlations, the analysis applies 5 classical optimization techniques for. non-linear functions' Lto i 1 .

determine the minimum fuel volunies and associated geometries

! (i.e., fire area and spill depth) necessary to exceed the damage criteria for the cables of concern at the elevations of interest I within an enclosure. ,

k i .. I

'[]. - 1 a ,

a I ,

4 ,

l

-J .j

% e i

1p i - t 4

i i t

.d

'a , y 1

z

+

-  ; I l

I i e.

k, eI t

[

O e

4 y

?

T

~ ~

O l

4 ..

e

( t

' . f'

,- l I \

s' -

l .i. ,

i

/

3' -4 ,,

I #. $ I

,f &

t t 's -

f. d(E.[,

i i 1' J' r

_f

l l

i Appendix B, Strati fic ation B-5 O

V

References:

, (1) J.S. Newman and J.P. Hill, " Assessment of Exposure Fire Hazards to Cable Tray.1", EPRI-NP-1675, Electric Power Research Institute, Palo Alto , CA, January, 1981.

(2) Heskestad and M.A. Delichatsius, "The Initial Convective G.

Flow in Fire", Report R C7 9 s-T-2, Factory Mutual Research Co rpo ra tio n , Norwood, MA, January, 1979 i (3) T.Z. Harmathy, "Some Overlooked Aspects of the Severity of Compartment Fires" , Fire Safety Journal, 3(1980/1981), pp.

261-271.

(3) T.Z. Harmathy, " Ef fec t of the Nature of Fuel on the Characteristics of Fully Developed Compartment Fires" , Fire and Materials, V3, N3 (1979), PP. 49-60.

1 g

L t

I t

I

{-

S -- .

T I

- , _ _ . . - - . ~ - - - -

., , - .~. ,

. _. _ . - - . ~ . _ - . . ._. -- -_.

I s

- 1

(- f\Q -

GAS TEMPERATURES, CAS VELOCITIES AND TOTAL liEAT FLUXES

. I i

VERSUS POSITION FOR ENCLOSURE FIRE TEST EPOO8 i l 4

(70 s AFTER IGNITION)

Gas Gas Total  !

Vertical Temperature Velocity Percent i HeatFgux Station Position (*C) (m/s) (kW/m ) Radiative 1 0.98H 387 5.0 20.4 7.9 ,

2 458 6.4 24.9 9.4 3 429 5.1 20.5 6.5 4 457 5.3 23.1 7.9 5 406 2.8 17.1 7.1  !

1 0.90H 364 1.5 12.5 6.5 2 356 1.9 12.2 6.8 l 3 328 2.1 11.8 5.2 4 0- 342 1.9 12.5 6.0 5 385 1.4 13.4 7.1 1 0.70H 315 1.5 11.0 7.4 2 294 1.5 9.7 4.3 3 299 1.5 10.0 7 /3 l 4 297 1.9 11.0 7.6 i 5, 311 1.1 10.1 9.9

(. 1 0.50H 269 2.4 10.9 8.9 v . 2 268 2.7 10.9 9.1 i

3 267 1.7 9.1 5.6 4 258 1.3 7.9 3.9  !

5 256 0.8 7.1 5.7 ,

l 1 0.30H 232 1.7 8.0 5.0

2 241 2.8, 9.2 4.7 .

i 3 218 2.2 7.7 5.8 i 4 222 1.7 6.1 7.5 l i 5 217 0.5 4.7 5.0 .

I Table B-1 .

,1 -; .

i Reproduced from Newman, J.S. and Hill, J.P., " Assessment

of Exposure Fire Hazards to Cable Trays", EPRI-NP-1675, Slectric Power Research Institute, Palo Alto, CA, January, 1981 I

t-I

(p V -

Smoke Detector Activation ( 1)

/ Sprinkler Activation (138 *C Link)

(

25 '

50C f

a

.5

. o 5 20 400 .,c

< o E 515 Nm 300 U 3: #. e x6 y

=

a

• u C =

s 10 200 E

[8 [

~

( 7 Onset of le Damage g Human Response To I 5 Fire Detection By g

10 0 Smoke Detector  ;

e 0 ,

20 0 60 120 180 240 300

, Time From ignition (s)

Heat flux and gas temperature at ceiling (Station 4) '

versus time from ignition for Test EP008 Figure B-1 -

e i

f

) Reproduced from Newman, J.S. and Hill, J.P., f

" Assessment of Exposure Fire Hazards to Cable * '

Trays", EPRI-NP-1675, Electric Power Research Institute, Palo Alto,'CA, January 1981.  ;

k.

0 l

t i

1.0

'O' Methanol '( 0.615 m dio.pon)' )'h = 0.98'H O Methanol (l.22 m dia.pon) e h = 0.90 H '

I A Methanol (l.74 m dio. pan) Oh 2 0.70 H i  ! i i i - 1 i V Heptone (0.61 m dio. pan Oh = 0.50H ~~~i '

i '

n i  ; i i Oh = 0.30H j' id 1 I i l ll 8 i i i ! Ii i i I O _ __ _I l I l _!I l ll  ! l l l I!* llI 9 f F - i*.-L.iJJDj NM i I

I I

i I  : j._ I I I i

$ i'7~ ^ -!hQ F ..

i ; ]l -

~ -

Correlation

,j '1 $

l v . 4 i'ib 7

'i'l -]

I F-.- i  ! '

Obtained g

,b E b -- ! [l i l i ih- h,' ,

i.Ll by Plotting tr

, P-- - -

7-g4'i H-  ! l : ! ll EPRI Data O.1 5 ----

C\ y E i i I i N  !\i e '! I I i I -

l\ i\

L, I i

!  ! 1 i l \ i

- i

l ,

L \- -k---j-+t-l- r-i h

_ l _1C, ai

! ' i t I

. !\; 1. t '

,  ? i I 6 ' i \ ,_ ' ' -

~

! l i i h ii I kl .'!

l  !

! l

- r_ _

i 1

I  !\ _l ' l li i I i I l '

l l ,

~

i

!. -}

t  ;

j l

'O.0 01 0.01 SCALED FORCED VENTILATION RATE. -

Of I

(

H 5/2 ml/2.s )

Scaled !! eat Flux versus Scaled Forced Ventilation Rate i

Figure B -2 - l im

\-i ) Reproduced from Newman, J.S. and Hill, J.P., " Assess-ment of Exposure Fire Hazards to Cable Trays", EPRI-NP-1675, Electric Power Research Institute, Palo Alto, CA, January 1981.

O t)

% APPENDIX C Diffusion Plumes A low-level fire in an enclosure develops a turbulent, b uo ya n t , diffusion plume which flows upward towards the ceiling or the first horizontal sur face. Driving the upward flow of hot gases are the gravitational forces acting on the difference in density between the plume and its ambient environment, a condition which poses a problem for the analyst to consider. An understanding of the physics of such plumes is esential to the modeling of the effects of such plumes on immersed materials and components. Fo r tun atel y , recent developments as discrised in the literature allow for the prediction of the effects of such plumes.

O The history of the modeling of turbulent buoyant diffusion plumes is fairly recent. An early description of the flow of buoyant plumes published in 1941 is attributable to Schmidt (1).

In a series of experiments involving convective plumes of air above small sources, Schmidt noted the tendency of buoyant plumes to exhibit conical patterns in turbulent vertical flo w . Assuming symmetry conditions existed, Schmidt generated velocity and temperature profiles for constant ambient temperatures involving point and line sources and v eri fied their accuracy against experimental data.

Batchelor (2) extended Schmidt's results to both stratified and uniform environments in a manner similar to Rouse et al. (3).

(]) These classical relationships ar reproduced below:

Appendix.C, Diffusion Plumes C-2 (2) u= Fa 1/3Z-1/3 r i f 1(E) j g' = Fa 1/3Z-5/3 fI}r 2E I

i d = Az 1

where F E buoyancy / unit time a

j source 1 -

j. = 2w / U g'rdr i O O

Ap g' E buoyancy = 8 p a

3 j () z E height above source i r E radial distance from plume axis or centerline 1

i' g = acceleration of gravity

}

Ap = density difference between local and i ambient gas a.

p = ambient density

a

{ U = mean vertical velocity in plume i

i j d = plume radius i

A = dimensionless constant O

t 4

-w .,m. - - _. .,.--...._.,e ,oryn.n- -.,-4 . . . _ . _ . _ , _ _ , - . , we. .m., .,_..v._,=c ,_-,...-3, , .,.,,.,.wm,. , , . ,

Appendix C, Diffusion Plumes c-3 In defining these relationships , and the forms o f f)(r/z) f2 (r/z) were initially undetermined although it may be apparent that boundary conditions require that they be at once continuous and well-behaved. This consideration was confirmed through a series of experiments involving hot air in a large room by Rouse et al. (3) where it was demonstrated that both the mean tempera-ture and the velocity profiles were essentially Gaussian. On this basis, Batchelor's relationships become:

2 U -

4 7F a 1/3Z -1/38 _( 96r )

2 C'~ 1/33 -5/3e -( 71r )

g, = 3jy a

z At this point, the development of a theory for buoyant diffusion plumes is limited by the mixing lengF1 theories which fo rm the basis for the similarity solution approach taken by Batchelor (2). These assumptions imply a loss of generality of Batchelor's functions for plumes diffusing into non-uniform gas temperatures. However, this difficulty is overcome through the l

l use of an entrainment assumption attributable to Taylor (4) for l air blast phenomena associated with nuclear detonations. This l

very fundamental assumption relates the mean in flow velocity across a plume edge to the local mean vertical velocity primarily.

l () through entrainment. Morton et al. (5) applied this asumption to the study of convection currents.

~

Appendix C, Diffusion Plumes C-4 As reported in Stavrianidis (6), three principal assumptions are made by Morton et al. (5).

(1) The largest local variations of density in the field of motion are small in comparison to some chosen reference density.

(2) The mechanics of entrainment can be represented fully by taking a mean radial in flow velocity across some suitably defined "mean outer boundary" as proportional to the mean vertical velocity on the plume axis at that height. Equivalently, V = Eoo U

where E 0.1 from Stavrianidis (6) and Turner (2) o=

U o= mean vertical velocity on plume centerline (3) The mean profiles of longitudinal velocity, temperature and density are similar in shape at all elevations in the plume.

These relationships apply to weakly buo yant plumes.

Extension of the theory to strongly buoyant plumes initially leads to a redefinition of the local entrainment function due to Morton (8):

P h E E =

[0 3 4

O With this mod i fic ation for the local entrainment function, solution of the general plume conservation equations for the case i

of the strongly buoyant plume was shown by Morton to be essen-tially equivalent to that of the weakly buoyant plume with larger convective heat release rates. Heskestad (9) subsequently

() con firmed this generality inside the flame envelope in a series o f experiments.

Appendix C, Di f fusion Plumes C-5 O

LJ With this background, it is apparent that turbulent, buoyant, diffusion plumes could be described mathematically in terms of convective heat release rates and position above the

. source. Stavrianidis (6) extended this basis in a series of experiments involving large scale hydrocarbon fires which measured the actual heat release rate in the plume. The red e fin ed plume laws correlated to.Stavrianidis' data yield, independent of fuel type:

)

AT = 0.092Q c (*-Zo)~

• z2 ,

U = 1.20Q c i Z-Z o) e 2

(:) .

where IT = normalized excess temperature on plume centerline T-T a Ta T = mean plume temperature T ambient temperature a=

1 O c= ctual convective heat release rate z = height above physical source z height of virtual source above o= physical source ,

/O b

- ~ _ . - ,

> Appendix C, Diffusion Plumes C-6

. ) Stavrianidis demonstrated the validity of these correlations well into the flame envelope to a point of divergence noted for ,

plume gas temperatures. The data reveals a constant maximum value for temperature of 1235 K for heptane, methanol, and

-silicone oil fires. The point of divergence is defined as the critical height, a function solely of the convective heat release rate, and given by:

z 0.130 c e= +Z o i

The determination of the height of the vertical source is given by:

z 7 54F /5 ( ,b 8 /5 5 o= ) - 0.15Qc i

T pa where F =

i Pa8 m = fuel vaporization rate

= Qc a

c AHT H

e = convective heat of combustion H

T= theoretical heat of combustion S = stoichiometric fuel-oxygen ratio

,~

()

- a

Appendix C, Diffusion Plumes C-7

(]) With these experimentally derived relationships, it is possible to calculate a number of parameters of interest relative to the exposure fire problem, in particular:

(1) Plume temperatures above a pool fire, (2) Gas velocities above a pool fire, (3) Heat flux delivered to a point above a pool fire, (4) Radiative heat flux associated with luminous fl am e s .

Each of these calculations is of value in the quantitative fire hazards analysis contained in this report. This appendix will cover those aspects related to the heat flux associated with diffusion plumes.

The problem of plume impingement is treated in this analysis in three distinct approaches:

(1) Stagnation heat flux issociated with direct plume, impingement on a horizontal surface.

(2) Cross flow heat flux to a cylinder (cable) associated with immersion in a turbulent buoyant plume.

(3) Parallel flow along a plate associated with immersion in a turbulent buoyant plume.

Ax is ymmetric fir e-ind uc ed flow beneath a flat horizontal

, sur face such as a ceiling has been discussed in the literature for some time. Early work includes that of Pickard et al. (10) and Thomas (11). The theory, however, did not progress to the level of generality until Alpe r t (12) developed a basis for the accurate prediction of turbulent ceiling jets as a function of the heat release rate and distance to the ceiling. Alpert's analytical work, which was verified through experiments, demon-strated the validity of using small-scale models to predict the

Appendix C, Diffusion Plumes C-8 r

(h) behavior of large-scale ceiling jets.

The basis for Alpert's work includes the top-hat source pro files of Morton et al. (5) and the Gaussian tempera-ture/ velocity profiles of Rouse et al. (3). Alpert's model views the ceiling jet as a boundary layer divided into two regions: an outer region where entrainment occurs as a result of turbulent mixing and a viscous essentially laminar sublayer at the horizon-tal sur fac e . Data taken in Alpert's experiments indicates a decline in entrainment by an order of magnitude 3-4 ceiling heights from the fire axis. A significant decline in ceiling temperature as well as an increase in jet thickness is also noted 3-5 ceiling heights from the fire axis. Finally, the stagnation fg region is considered to extend radially outward to a distance of U approximately 20% of the ceiling height prior to transitioning to.

a uniform stratified layer. Semi-Gaussian profiles are assumed for the transition or turning region.

You and Faeth (13) extend Alpert's work and determine a heat flux within the stagnation region ( r/h < 0.2) as a function of gas properties and the fire's heat release rate:

q'H2 = 31. 2Pr- 3/s Ra~ !6 l Q i when Pr = Prandtl number (-0 7)

Ra = Rayleigh number

= 88DH2 9 (10 <Ra<10 14 )

pC v 3 p

t

.. .-_. -- . .-- ._ _. . = . . .. - ___ . .- . . - .

! I Appendix C, Diffusion Plumes C-9 O

t Hp

< 15 H ,

l H = ceiling height  ;

H p= free flame height i

i g = gravitational constant

} B = coefficient of columetric expansion i

i p = density ,

v = ceiling radial velocity for the jet

! O- q

= heat flux .,

c heat capacity

p=

~

I si 2 4 .H 1/3

= 0 . 0 34 ( # )

Q H j

for 1010<Ra<2 x 10 13 1

1 i '

Pr-0 7 H

f

^

<0.6 H

f I

LO I

i r

r-,ea-'- --=r -- - - -- ywH = - -- -

Appendix C, Diffusion Plumes C-10

/"N

(_),

References:

(1) W.Z. Sc hm id t , " Turbulent Propagation of a Stream of Heated Air", Z. Agnew Math. Mech.; V21, pp. 265-351, (1941).

(2) G.K. Batchelor, " He a t Convection and Buoyancy Effects in Fl uid s" , Quarterly Journal of the Royal Meteorological Society; V80, pp. 339-358, (1954).

(3) M. Rouse, C.S. Yih, and H.W. Humphreys, " Gravitational Conv ec tion from a Boundary Source"; Tellus, V4, pp. 201-210, (1952).

(4) G.I. Taylor , " Dynamics o f a Mass o f Hot Gas Rising in Air",

U.S. Atomic Energy Commission , MCCD, 919, LADC, 276, (1945).

(5) B. R . Morton, G.I. Taylor and J.S. Turner, " Turb ulen t Gravitational Co nv ec.tio n for Maintained and Instantaneous So u r c e s" , Procedings of the Royal Society, A236, pp. 1-23, (1956).

(6) P. Stavrianidis, "The Behavior of Plumes Above Pool Fires",

A Thesis Presented to the Faculty of the Department of Mechanical Engineering of Northeastern University, Boston M A, August 1980.

i O (7) J.S. Turner, " Buo yanc y Effects in Fl uid s" , Cambridge, University Press , Cambridge, England, 1973 (8) B.R. Morton, " Mod eling Fire Plumes", Tenth Symposium (International) on Combustion, The Combustion Institute, Pitt sb urgh , PA, 1T65 (9) G. Heskestad, " Optimization of Sprinkler Fire Protection",

FMRC Report 18972, Factory Mutual Research Co rpo ratio n ,

Nor wood , MA, 1974.

(10) R.W. Pickard, D. Hird, and P. Nash, JFR0 Note 247, Fire Research Station, Boreham Wood , Huts, England, 1957 (11) P.H.- Thomas, JFR0 Note 141, Fire Research Station, Boreham Wood, Huts, England, (1955).

(12) R.L. Alpert, " Turbulent Ceiling--Jet Induced by Large-Scale Fires"; Combustion Science and Technology, V11, pp. 197-213 (1975).

(13) H.Z. You and G.M. Faeth, " Ceiling Heat Transfer During Fire Plume and Fire Impingement", Fire and Materials, V3 N3, pp.

140-147, (1979).

m l, ) APPENDIX D Cable Failure Criteria A concept of an electrical cable damage criterion with a sound technical basis is essential to the modeling of the effects of fire. The approach utilized in this report focuses on the flammability properties of the materials of concern and the effects of incident heat flux on the ability of the cable to function properly.

Electrical cables consist of several individual insulated I

I cables bounded within a jacket designed to protect the cables from external hazards while ensuring adequate cooling under normal conditions. Generally, both the insulation and the jacket

(]) are manufactured from polymeric materials. Typical of such macromolecules is polyethylene, a long molecule based on th8 ethylene monomer (-CH 2 CH2 -)n chain. Pol ymeriza tion of vinyl monomers with chloride as the pendant group yields pol yv in ylchlo rid e , a jacket material found in electric cables in older nuclear units.

Thermal decomposition of polymeric materials (pyrolysis) results in the physical degradation of a cable's insulation and produces combustible gases that may ignite in the presence of an ignition source. The process of pyrolysis requires a minimum heat flux exposure and may be measured in terms of the insulation and jacket mass loss rate. Higher mass loss rates at a particu-lar heat flux exposure suggest that more rapid combustion and' higher overall heat re' lease rates are possible with the material.

i .. . . . .

Appendix D, Cable Failure Criteria D-2

() The detailed study of material flammability properties and an understanding of the pyrolysis / combustion process requires the use of a calorimeter capabla of measuring mass loss rates, analyzing gaseous products, and determining heat release rates under varying incident fl ux e s . Such an apparatus has been in use for several years at Factory Mutual Research Corporation as described by Tewarson and Pion (1). This apparatus presents results for ignition , mass pyrolysis / burning rate, product mass generation rates, heat release rates, optical transmission through the products, and material thermal inertia. Experimental data for common polymeric solids and liquid hydrocarbons is presented in Tewarson (2) and Tewarson et al. (3).

With the objective of understanding the physical processes underlying electrical cable flammab ilit y , the Electric Po wer, Research Institute funded research at Factory Mutual Research Corporation utilizing the Tewarson apparatus. Initial results were reported in Tewarson et al. (4) for twenty (20) different cable specimens which included a number of IEEE-383 qualified cables [IEEE (5)]. Cables evaluated in this program are listed in Table D-1. This program was the most comprehensive study of electrical cable flammability then in existence. With the Tewar-son work as a basis, the transition from a fundamental and com-prehensive understanding of the electrical cable flammability l parameters to a damageability criteria is not especially d i f fi-cult. Before making that transition, however, it is important to

() discuss the relationship of the flammability parameters to the IEEE-383 fire test and the meaning of the standard itself. ,

Appendix D, Cable Failure Criteria D-3 The criteria giv en fo r the IEEE-383 flame test is as follows :

(1) The fire test should demonstrate that the cable does not propagate fire even if its outer covering and insulation have been destroyed in the area of flame impingement.

(2) The fire test should approximate installed conditions and should provide consistent results.

This test is essentially a "go/no-go" test which is generally considered appropriate for all cable arrangement conditions.

Tewarson et al. (4) demonstrated the validity of the intuitive notion, however, that cable flammability is actually dependent on multiple parameters. In that series of tests it was demonstrated that some electrical cables which were not qualified according to IEEE-383 exhibited flammability characteristics more desirable than those of the qualified cables tested. In ?;ct, the only statement that Tewarson could make concerning the IEEE-383 tested cables was that the actual heat release rates were less than about 350 kW/m2 for an external Seat flux of 60 kW/m2 This is not to suggest that IEEE-383 cable does not demonstrate good fire resistance qualities but rather to illustrate the complex pheno-menon associated with fire and to highlight the fact that some un quali fied IEEE-383 cables exhibited equally desirable pe r fo r-mance characteristics.

The value of controlled laboratory experiments in categorizing cable flammability has been clearly demonstrated.

(). As thermal conditions vary.with a fire, different electrical cables undergo physical and chemical changes depending upon their

Appendix D, Cable Failure Criteria D-4 chemical composition. In this context the concept of damageability must be related to the thermal conditions which cause impairment to the cable's function.

This concept of damageability was examined by Lee (6) using data presented by Tewarson et al. (4). Four basic phenomena were examined and are presented below in increasing magnitude of damage.

o Insulation degradation--the onset of jacket mass loss from a cable.

o Elec tric al failure under piloted conditions--the onset of short circuit between conductors f- a 70 VDC signal under piloted conditions.

o Piloted ignition--the onset of ignition in the presence

-)

s-of a small pilot fl am e .

o Auto-ignition--the onset o f self ignition. .

For each cable, Lee plotted the external heat flux incident of the specimen against the inverse of the time to failure.

These plots yielded the following in formation for each specimen :

(1) Critical heat flux--that incident heat flux above which the cable damage process is expected to occur.

(2) Critical energy--that amount of energy exposure necessary to cause cable failure to occur given a heat flux at or above the critical value.

The critical heat fl ux is obtained through the linear extrapola-tion of a regression curve to the heat flux intercept as the time to failure approaches in finity. The critical energy is d e fin ed as the inverse slope of the regression curve on the heat fl ux-( )) . inverse time to failure (x-y) axis. Figures D-1, D-2, and D-3 illustrate the case o f cross-linked polyethylene cables with

Appendix D, Cable Failure Criteria D-5 O

neoprene jackets for the four criteria defined.

It should be emphasized at this point that the data presented for each cable represents fundamental properties of the cable without taking credit for the mitigating effects associated with the use of cable trays. Such effects include and are not necessari1y ,

limited to self-shielding and conductive cooling.

Thus, these values should be considered to be conservative in the usual sense and offer the unique advantage of understanding relative per formanc e characteristics independent of qualifica-tion. This point is especially meaningful when evaluating the relative fire resistance of electrical cables installed in nuclear power plants prior to the implementation of IEEE-383 (O

%/ The fire hazards analysis utilizes this. cuncept for electric cable failure criteria when modeling the effects of exposur fires on safe shutdown equipment. In general, the more limiting criterion of electrical failure is considered unless otherwise s peci fied . The use of electrical failure as a criterion rather than cable ignition is also useful in that it focuses on the loss of function aspect of the fire protection issue. In cases where cable tray fires are postulated , their ignition is investigated using the piloted ignition criteria for cable flammability defined by parameters developed in Tewarson et al. (4). Thus, issues related to variation in the ignition criteria associated with fully developed fires are moot.

O

Appendix D, Cable Failure Criteria D-6 A

V

References:

(1) A. Tewarson and R.F. Pion, " A Laboratory Scale Test Method for the Measur ement of Flammability Parameters", FMRC 22524, Prepared for Products Research Committee , National Bureau of Standards, U.S. Department of Commerce by Factory Mutual Research Corporation, Norwood, M A, October, 1977 (2) A. Tewarson, " Ex perim en t al Ev alua tion of Flammability Parameters of Polymeric Materials", FMRC J.I.1A6R1, Prepared for Products Research Committee, National Bureau of Standards, U.S. Department of Commerce by Factory Mutual Research Corporation, No r wood , MA, February, 1979 (3) A. Tewarson, J.L. Lee, and R.F. Pion , " Fire Behavior of Trans former Dielectric Insulating Fluid s", Report DOT-TSC-1703, U.S. Department o f Commerce , Transportation Systems Center, Cambridge, M A, September, 1979 (4) A. Tewarson, J.L. Lee, and R.F. Pion, " Categorization of Cable Flammability Part 1: Laboratory Evaluation of Cable Flammability Parameters", EPRI-NP-1200 Part 1, Electric Po wer Research Institute, Palo Alto, C A, October, 1979

( )1 (5) IEEE, "IEEE Standard for Type Test of Class 1E Electric Cables, Field Splices, and Connections for Nuclear Po wer.

Generating Stations", ANSI /IEEE STD 383-1974 (ANSI N41.10-1975), The Institute of Electrical and Electronic Engineers, Inc., New YorkJber, October, 1978.

(6) J.L. Lee , " A Study o f Damageability o f Electrical Cables in Simulated Fire Environments", EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.

4

(

Q) i

1 l

V TABLE D-1 CABI.E SAMPLES USED IN THE STUDY Insulation /

Jacket Mata= Insulation Jacket Materials conductor Outer Cable rials (t of remaining as char (t of initial wt. of insulation / IEEE-383 Insulation /Jjcket No. Site Diameter total cable Rating Number Materials (AWC) in. (m) weight jacket materials)

Polyethylene (PE)/No Jacket tow density PE 1 14 0.12810.003) 23.9 0.10 -

1 (idPE), no jacket Polyethylene / Polyvinyl chloride (PE/PVC) 1 - 0.945(0.024) 15.6 21.9 3 PE/PVC 1 12 0.164(0.004) 26.5 0.6 Pail 4 PE/PVC 3 - 0.438(0.011) 49.9 20.8 Pall 5 PE/PVC 5 - 0.748(0.019) 51.0 25.6 6 PE/PVC 7 12 - 1.000(0.025) 57.8 24.4 PE/Pvc Polyethylene. Polypropylene/Chlorosulfonated Polyethylene (PE, PP/Cl*S*PE) 23.2 41.6 Pass O PE.PP/Cl*S*PE 1 - 0.445(0.011)

(silicone coating) 40.2 46.4 Pass 9 PE,PP/rpC1*S*PE 1 6 0.368(0.009) 42.9 45.6 Pass 10 PE,PF/Ci'S*PE 1 12 0.192(0.005) 77.1 48.3 Pass 11 PE.PP/ciaS*PE 5 14 0.668(0.017) 0.426(0.011) 77.4 40.5 Pass 12 PE,PP/Cl*S*PE 2 16 Crose-tinked Polyethylene /Crose-Linked Poyethylene (XPE/XPE) 61.4 44.9 Pass b 13 XPE/rRXPE 3 12 0.458(0.012)

Pass 14 XPE/XPE 2 14 0.377(0.010) 73.5 -

Cross-Linked Polyethylene /Chlorosulfonated Polyethylene (XPE/Cies*PE) 0.368(0.009) 56.2 29.5 Pass 15 PRXPE/Cl*S*PE 4 16 4 16 0.442(0.011) 62.1 31.0 Pass 16 XPE/Cl*S*PE Cross Linked Polyethylene / Neoprene (XPE/Neo) 16 0.369(0.009) 73.2 43.9 Pass 17 XPE/Neo 3 2 XPE/Neo 7 12 0.630(0.016) 53.6 -

Polyethylene, Nylon / Polyvinyl chloride, Nylon (PE, Ny/PVC, Ny) le PE, Hy/PVC, Ny 7 12 0.526(0.013) 39.9 -

19 PE, Ny/PVC, Ny 7 12 0.520(0.013) 43.5 teflon 20 Teflon 34 - 0.516(0.013) 48.9 3.9 y...

Silicone 21 Silicone, glass 1 - 0.363(0.009) 34.0 -

braid .

22 Silicone, glass 9 14 0.875(0.022) 10.5 . 59.4 Pass brald/ asbestos t

1. Ceneric class as given by the suppliers. Cable samples belonging to similar generic class may not be similar because of different types and amounts of unknown additives in the c*ble samples.

b re = with fire retardant chemical (Reproduced frcm A. Tewarson, J. L. Lee, and R. F. Pion, " Categorization of Cable Flammability Part 1: Laboratory Evaluation of Cable Flammability Parameters", EPRI-NP-1200, Part 1, Electric Power Research Insti-tute, Palo Alto, CA, October,1979.) .

i'V t

FIGURE D-1 to i i i

, , i 9 -

e-y 7 -

9 -

~

-7 6 -

7 0 4)

~

5 (3 h -

k Degrodotion Energy, E id f, ,

e l/ Slope / -

()

34 -

2 y Sompie 17 (3/c)

~

[3 -

P h _

~

Sompie 2 -

2 -

g7fej

~

/

l -

l/

/

! Critical Flus of DeGradotion , q'] -

- /j 70 0 30 40 50 60 O 10 20 2

Eaternoi Heat Flum (kW/m 3 Thermal Degradation of XPE/ Neoprene Cables (Reproduced from J. L. Lee, "A Study of Damageability of

~

Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.)

l i

k i

O FIGURE D-2 It i i . i i i i

12 gi _

0 Sompte 5 - PE/PVC -

O Sompie 59 - EPR/Hypolon -

0 Sompte 60 - Telton/ Teflon

• Sample 22 - Silicone /Asbesloe

~

'O e Sompte 56 - Teflon / Teflon

. A Sompte 57 - Silicone /Asbellos .

A Sample 17 - XPE/ Neoprene -

9 -

0 Sompte 2 - XPE/ Neoprene a Samrie 11 - EPR /Hypolon ~

$ Sompte 6 - PE /PVC o

]e -

7 so 7 -

l c .

6 - 0 -

y o 3 -

g5 -

2 *

.9 4 -

e--

5 .

3 2 - I -

I -

i 1

" I

/ i -

l - / / I

/ /s l -

/ // l t I a > . 2 I f f Oo so. 20 3o 40 50 SO 70 to External Hoot Flus ikW/mtg ,

Piloted Ignition of Cables Under Various Extemal Heat Flux f

O (Reproduced from J. L. Lee, "A Study of Damageability of Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.)

(O FIGURE D-3 5 , , , , , i n Ignllion of XPE / Neoprene Cable (No.2) 4 -

sj 9 o

~ -

.-[3 c

. 3 ~Pil9ted Ignition db [$ -

22 -

E r .

h -

l -

Auto ignition

- u g

M , i i

40 50 60 70 10 20 30 2 Entorno! Hoot Flux (KW/m } .

Auto and Piloted Ignition of XPE/ Neoprene Al" l is the Cable (#2) at Various External Heat Flux.

dif ference between the critical flux of piloted ignition and that of non-piloted ignition.

(Reproduced from J. L. Lee, "A Study of Damageability

, of Electrical Cables in Simulated Fire Environments",

EPRI-NP-1767, Electric Power Research Institute, Palo Alto, CA, March, 1981.)

O APPENDIX E Radiation Radiation can be a significant contributor to the overall heat . flux produced as a result of a fire and must be accounted fo r in properly modeling exposure fires in nuclear power plants.

This appendix discusses the approach taken in this report for modeling the effects of radiation from such fires.

The combustion of organic materials such as liquid hydrocarbons is an exothermic reaction. The energy released as a result of such reactions leads to the generation of a high temperature turbulent buoyant diffusion-plume consisting of both gaseous byproducts of combustion and soot particles. The energy (7-)d contained within this plume is transferred to the environment through two processes: (1) convection associated with momentum of the plume and (2) radiation from the plume.

Molecules in an excited state transfer energy via radiation principally through band emission. For the fundamental products o f combustion , i.e., CO2 , CO, H2 O and soot, such emission tends to be concentrated in the visible and infrared regions typically less than 15 (1). The energy transferred by radiation over these wavelengths depends on a number of parameters including average temperature of the source and its constancy.

Historically, fire models and the discipline of fire protection engineering have addressed radiation in considering

() the offect's of an initial exposure fire. Radiant heating has l

been found to be a dominant mechanism in the development of larg-1 I

Appendix E, Radiation E-2

(")

(_/ -

scale conflagrations. This focus is inherently reflected in the use of temperature as a standard of measurement in tests determining fir e resistance. Typical of this genre are the standards published by the National Fire Protection Association for qualifying barriers and doors for commercial structures and the E-152 Test issued by the Americ an Scciety for Testing and Materials (2, 3). These tests are essentially oven tests employing radiant heaters in an attempt to model the dominant heat transfer process in large scale con flagration s involving residential and commercial structures coasisting of and containing high densities of combustible material.

The early application of classical radiative heat transfer

() techniques to the problem of determining sa fe horizontal separation distances for building fires is documented in reportN issued in the post-war period by British and Japanese investigators (4, 5). These and later reports published in the 1950s and 1960s retained the concept cT horizontal separation as a principal means of protecting adjacent combustible material (i.e., neighboring buildings) from the intensive effects of major building fires where radiant heat transfer in the open air is the dominant mechanism for damage. During this period, applications of principles for modeling radiant heating, well known in other scientific disciplines , were also made t, such distinct problems as the effects of fire-induced flows through windows and doors on adjacent structures, effects of wind on fl ame s , the sensitivity ^

i (S

\-)

of radiant energy to different flame temperatures and the impact l

l 1

I l

I Appendix E, Radiation E-3 s () of various wall materials. The conclusions from such studies tended .to emphasize the difficulty of developing generalized empirical relationships independent of scientifically based theory and the im po rtanc e of understanding the effects of material flammability parameters in modeling the radiative effects of fire.

At a more fundamental level, the effects of radiation may be tied to the gaseous dynamics associated with the fire plume itself. With its dominant contributions in both the visible and in fr ared regions of the electromagnetic spectra, the natural focus for a radiation model therefore becomes one based on the material flammability parameters and , in particular, the height of the visible portion of the turbulent buoyant diffusion plume.

In this regard, F.R. Steward's work, (1970), assumes an important role in providing a comprehensive statement of the dynamics of fire plumes for subsequent researchers (6) .

Later work by Dayan and Tien (1974) builda on Steward's research in ~ developing a radiant heat flux model which o ffer s excellent agreement with experimental data (7). This- model assumes good mixing associated with combustion conditions in the burning zone so as to provide an essentially uni fo rm gaseous temperature and chemical species concentration in a cylindrical fo rm . The use of cylindrical form does not appear to suffer a i loss of generality relative to some other shape such as one which is either conical or hyperbolic and, in fact, may well be a more

([). accurate representative of average fire conditions. Of greater significance than fire shape in the modeling of radiant heating

Y [ >

i s r

i Appendix E, Radiation f E -4 5 , .

1 is that of soot and gaseous temperature. ,

s 3 3 3

\ g Soot and gaseous temperattre,. directly, a frect the , emissivity p i'

\

associated with the luminous flames o f a ' fire.

\ This effect . is ,

t 9  %

seen in the following form ' o f, the Ste fan'-Boltzmann law:

,i I

Q = ECT 4 s

.- ~

I s/ -

where Q = radiant energy transfc.c rate t

E = . emissi@ity (dimensionless) .

c

f

, c, 0 = Stefan-Boltzmann constant i

/ *6

\ . \o y.

\

T = absolute blackbcdy temperatur's i

\

l The emissivity of a flame essent'ially ' determines the pro po r tio'n ,

l of energy released in the form _ 'of radiant energy. The individ'ual'  ; >

\

components of the total emissiv~ity may be broken up as follow!s :

f, j i , ,

i t i / 3 l

E = E g+E 3 , il

l - -

where E = total emissivity associated "

with the , fire '

, > \

s E eniissivity of the hot gas '

e 8= within th,e burning zone / -

i 7

E 3

= emissivity of the luminous soot  ;

within the burning zone ,

s.

^ '

/g

.k -

a, 4

\. ' .<

s a $

\

-s Appendix E, Radiation E-5

( Felske and Tien (1973) provide an analytical basis supported by experimental data for understanding the parametric

[ relationships of gaseous and soot emissivity (1). This understanding is a further development of an earlier description

~

provided by Hottel and Saro fim (8). In particular, the relationship of emissivity to spectral wavelength is given for the dominant emission species of water vapor , carbon dioxide and soot. This relationship is strongly affected by the partial pressures of the products of combustion. As in the case of other, well-behaved spectral functions, the use of an effective value for emissivity is supported by the data and may be provided J

over the range of sensitivity. This range occurs at wavelengths

, r~g shorter than the 15p and for infrared band and contains over 96

(/ ,

per cent of the total black body radiation emitted in a fire. ..

Focusing on gaseous emissivity for the moment, with the

/

assumption o f near-optimal fluid mixing and thermal conditions in a fi r e , combustion may be assumed to involve the following f

typical' reaction:

7[

( CH2 )X + ( ) X02+XCO2+XHO 2 Under ideal conditions, the partial pressure of CO is 0.131 atm, 2

given a standard envirou. ant where the partial pressure of oxygen [

is 0.21 atm and the partial pressure of nitrogen-argon is 0.79 atm. From Hottel and Sarofim (8) and Hadvig (10), the gaseous s emissivity is described by:

f, / ETS g = 600.0 (PCO L 2 *}

1

Appendix E, Radiation E-6 O

(-) where Lm= mean beam length '

Tg= gaseous temperature PCO = partial pressure of CO2 2

For the case of an essentially in finite cylinder (i.e., an electrical cable):  !

Lm= 0 94D ,

where D = cylinder diameter This yields the following for the emissivity o f a hot gas:

/~T U [600][(0.131)(0.94D)]

E g= T 8 .

The gaseous temperature is assumed to be a uni fo rm 1255 K (1800 F) based on the work of Stavrianidis (1980) using pool fires consisting of heptane and acetone as fuel (9).

As in the case of gaseous emissivity, the contribution of [

soot to total emissivity may also be characterized by effectively 4

a single value. Here again, Felske and Tien (1) develop a view consistent with earlier work by Hottel and Saro fim (8). This view suggests that the mainstream of conditions involving the '

burning of liquid hydrocarbons, i.e., generally lower gaseous temperatures and longer volume of reaction path lengths asso-ciated with fairly efficient (energetic) combustion, the emis-Os sivity of soot may be bounded for the majority of cases. In

1 Appendix E, Radiation E-7

() these circumstances, a value o f 0.1 for the soot emissivity becomes limiting.

With this perspective, a cylindrical fire model is utilized to analyze the effects of radiant heating on the material of interest. The burning zone is described by a more current analytical model for turbulent buoyant diffusion plumes strongly, supported by excellent correlations with experimental data obtained under controlled conditions involving fairly large scale acetone and heptane fires (9) . This model is described in more detail in the appendix covering diffusion plumes.

! The radiant heat flux to an electrical cable from a l

postulated fire is therefore given by:

O 4" = (5.67 x 10

-12 Tg b

+

1.435 x 10-8 00.412 4 T

8 E) 21

.n where q = radiant heat flux incident on a cable D = cable diameter T g= gaseous temperature = 1200 K (1800 F)

F21 = con fig ur ation factor describing the fraction of heat flux delivered to a i

point by a radiant right cylinder This expression is accurate to within 5% fo r a gaseous l

temperature range of 1000 K-1600 K.

O

Appendix E, Radiation E-8 Heferences:

1 (1) J. D. Felske and C.L. Tien, " Calculation of the Emissivity of Luminous Flames", Combustion Science and Technology, V7, pp.

25-31 (1973).

(2) National Fire Protection Association, " Fire Tests - Building Construction and Materials", NFPA-25-1979 (3) American Society for Testing and Materials, " Standard Methods o f Fire Fests of Door Assemblies", ASTM-E-152-1978.

(4) R.C. Bevan and C.T. Webster, " Investigations on Building Fires, Part IV, Radiation from Building Fires", National i Building Studies Technical Paper #5, H.M. Stationery Office, l

! London, 1950.

(5)

K. Fujita, " Fire Spread in Japan - Fire Spread Caused by Fire Radiant Heat and Methods of Prevention", Tokohu University, Japan, 1948.

(6) F.R. Steward, " Prediction of the Height of Turbulent Di f fusion Buo yan t Fl am e s" , Combustion Science and i Technology, V2, pp. 203-212 (1970). *

() (7) A. Dayan and C.L. Tien , " Radiant Heating from a Cylindrical i Fire Column" , Combustion Science and _ Technology, V9, pp. 41- ,

47 (1974).

(8) II . C . Hottel and A.F. Sa ro fim , " Radiative Transfer" , McGraw '

liill Book Company, New York (1967).

(9) P. Stavrianidis, "The Behavior of Plumes Above Pool Fires",

A Thesis Presented to the Faculty of Northeastern 7 University, Bo ston , M A, 1980.

(10) S. Hadvig, " Gas Emissiv ity and Ab sorptiv ity  : A Thermod yn amic Stud y" , Journal of the Institute of Fuel, April, 1970.

O f

APPENDIX F Thermal Shields This appendix presents an analytical treatment of the e f fic ac y of baffles when used as thermal shields for the purpose of diverting hot fire gases from direct impingenent upon electrical cable. The results of this analysis provide a basis fo r determining the size such baffles need to be in order to protect a vertical stack of trays from convective heating associated with transient combustible exposure fires.

In fire protection reviews per formed subsequent to the Bro wns Ferry fire, licensees considered the guidelines of BTP

() APCSB9 5-1 Appendix A. This document assumes a flexible and multi-layered approach to backfitting fire protection measures to operating power plants. Such measures include the use of flame retardant coatings, suppression and baffles used as thermal shields. As a result of this process many operating plants.

upgraded their overall fire protection capability as ' documented in the safety evaluation report (SER) issued by the NRC Staff.

The BTP Appendix A fire hazards analysis led to the implementation of significant modifications at operating plants.

The value of such modifications was questioned , however, by the Commission in the issuance of 10CFR50 Appendix R in November 1980. While the Commission explicity highlighted the issue of-flame retardant coatings , it may be be inferred that the value of thermal shields was also subject to question. As in the case of

Appendix F, Thermal Shields F-2

) contings, the question turned to the lack of available data.

Phenomenological testing of baffles as thermal shields had been performed at Factory Mutual Research Corporation under the sponsorship of the Electric Potter Research Institute [ Ne wman and 11111 (1)]. In one test in a series involving the use of sprink-1ers and b a f fle s , a fire was ignited in a 1.2 meter diameter circular pan containing 17 gallons of #2 fuel oil located 1.8 meters beneath an electrical cable tray protected solely by a 13 mm. (0 5 in.) thick baffle composed of refractory material.

Temperatures recorded beneath the baffle were generally in excess of 700 0C. After immersion in the 3 7 meter high flames for over 15 minutes before the fire self-extinguished , an examination of the electrical cables showed no visual evidence of charring nor was there a loss of conductor continuity for a 70 Vdc signal at.

any time during the test.

Physical tests of this type are indicative of the pe r fo r-mance of baffles in protecting cable trays against the effects of exposure fires. The process involves the disruption of turbulent flow by a blunt body and may be modeled using standard fluid dynamics computer codes with detailed results available through-out the simulated flow field . This report, however, utilizes a data correlation based on a theoretically coherent approach based on an analysis of the turbulent mixing associated with the wake developed by the baffle. The treatment is by Schlichting (2) who j reports on velocity distributions generated in the mixing zones

() produced by blunt objects. The original data is reported by Tanner (3).

l 7

Appendix F, Thermal Shields F-3 As discussed in Schlichting (2) for a b a f fle o f width, w, located within a flow field characterized by an average velocity, U, the wake velocity at any point in the mixing zone is given by:

u=U 1 + erf

~

2

• )

/ '

y /

> A s

/ <

~ s'

/

>X >

ss N g

s s u U m W <---Xi/ d/  ?

/

/ ,/ )

> .1 b\/

s >

? N N

s 3 Y

> where,erf l is the error -

function of I x

Based on experimental work by Tanner (3) , (T is defined to be a function o f the angle , $ , of the leading edge of the object in the flow: p

/

/ $ 7 I /

s l'

! O' 14 l

30 10 s

l- - 60' 9 U

> l 120" 8 s I s 180a 7

\

l x O s .

i Therefore, a baffle analysis uses a value for 9 equal to 7 l

Appendix F, Thermal Shields F-4 O

If the protected zone boundary is defined to be bounded by u = 0.20 U

the width of the associated baffle in terms of the downstream extent of the protected zone is given by:

1 - erf "

, 0. 2 -

O.20 =

2

= 0.60 erf( 7w 0.2 7w 2X 0.2 w = 0.17 X 0.2 The choice of = 0.20 was based on the assumption that the heat flux will be reduced to 20% of the free stream value, as well as the velocity. Actually, the mixing will further reduce the heat flux by lower fluid temperatures downstream of the b a f fl e . The relationship between w and X0 2 identifies the area within which the velocities are below 20% of the free stream velocity. Thus, to create a protected zone around a vertical stack of trays approximately 6 ft. in height, this analysis

/~T

(_f suggests the installation of a baffle below the lowest tray with a width of at least 13 inches or the width of the tray, whichever l

l

Appendix F, Thermal Shields F-5 r

is larger. Ilowev er , the presence of the trays in the wake will lengthen the extent of the protected zone by inhibiting mixing layer growth. Therefore, the baffle width suggested in this analysis will be more than adequate to protect the stack of trays.

It is concluded on this basis that the barrier effect con-tributed by a vertical stack of closed-sided cable trays combined I

with the wake effect of a baffle will reduce the convective heat  ;

fluxes incident on cables within the trays due to an exposure fire directly beneath the trays, thereby preventing the onset of cable damage.

O -

! I t

+

e i

r O

V r

l l

l -

1 Appendix _F, Thermal Shields F-6 O References (1) J.S. Newman and J.P. Hill, " Assessment of Exposure Fire Hazards to Cable Trays", NP-1675, Electric Power Research Institute; Palo Alto , CA, January 1981.

l (2) H. Schlichting, Boundary Layer Theory, Seventh Edition.

McGraw-Hill Book Company; New York, New York, 1979 l (3) M. Tanner, " Ein flus s des Keilwinkels auf den Ahnlichkeitsparameter der turbulenten Vermischungszone in inkompressibler StrBmung", Forschg., Ing.-Wes., --39, 121-125

(1973).

i

'l O .

O

---

t -

r---->T 4 T w w-9--m*