NUREG/CP-0 181

International Collaborative

Project to Evaluate Fire

Models for Nuclear Power

Plant Applications: Proceedings of

5 th Meeting

Held at

National Institute of Standards and Technology

Gaithersburg, MD 20899

May 2-3, 2002

U.S. Nuclear Regulatory Commission tpkREG4

Office of Nuclear Regulatory Research 'IO

Washington, DC 20555-0001 Sv
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NUREG/CP-0181

International Collaborative

Project to Evaluate Fire

Models for Nuclear Power

Plant Applications: Proceedings of

5 th Meeting

Held at

National Institute of Standards and Technology

Gaithersburg, MD 20899

May 2-3, 2002

Manuscript Completed: May 2003

Date Published: October 2003

Prepared by:

M. K. Dey

Division of Risk Analysis and Applications

U.S. Nuclear Regulatory Commission

Washington, DC 20555-0001

A. Hamins

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899

S. Miles

Fire and Risk Sciences Division

Building Research Establishment Ltd., UK

(BRE)
-

NUREG/CP-0181, has been reproduced

from the best available copy.
Abstract

The 5' Meeting of the International Collaborative Project to Evaluate Fire Models for Nuclear

Power Plant Applications was hosted by the National Institute of Standards and Technology

(NIST), U.S. Department of Commerce and held at NIST headquarters at Gaithersburg,

Maryland on May 2 and 3, 2002. The organizing Committee for the meeting included Moni Dey

from the U.S. Nuclear Regulatory Commission (U.S. NRC), and Anthony Hamins from NIST.

Thirty three participants from five countries attended the international meeting.

The purpose of the 5' meeting was mainly to discuss the results of Benchmark Exercise # 2,

"Pool Fires in Large Halls," conducted in the project. Validation and regulatory applications of

fire models were also presented and discussed in the meeting. The results presented for Part I of

Benchmark Exercise # 2 were generally quite encouraging. While the general, qualitative, nature

of the experiments had been captured in the simulations, a number of issues had arisen.

Furthermore, the parametric analysis undertaken by a number of participants had yielded useful

information. Different conclusions have been drawn on the most significant, or controlling,

parameters. The combined effect of the choice of heat of combustion, combustion efficiency and

radiative fraction was found to be an important factor. The validation and application of several,

diverse fire models, ranging from empirical equations organized in worksheets to zone, lumpedparameter, and computational fluid dynamic (CFD) models, were presented and discussed at the

meeting. The discussions emphasized the need to validate and determine the accuracy of such

models, especially to understand the differences in the predictive capabilities and margins of

uncertainty for the different types of models over a range of fire scenarios. This information is

needed to establish safety factors and implement effective applications of these models in a

regulatory framework. The need to define credible fire scenarios and generate data for fire

sources, especially cable tray fires, was emphasized.

iii
Table of Contents

Abstract ................................ iii

Executive Summary ................... ............................. vii

Foreword . ......................................................... xi

Acknowledgments ........................................................... xiii

Acronyms and Initialisms ................................................. xv

1 Introduction ................................................ 1

2 Background ................................................ 3

3 Meeting Summary ............... ................................. 5

3.1 Benchmark Exercise # 2, "Pool Fires in Large Halls" ............ ............... 5

3.2 Validation and Regulatory Applications of Fire Models ....... ............... 11

3.3 Future Tasks and Benchmark Exercises ............ ...................... 11

Appendix A: Agenda for Meeting A-1

Appendix B: Specification of Benchmark Exercise # 2 B-1

Appendix C: Summary Papers C-1

Appendix D: View Graphs Used for Presentation D-1

v
Executive Summary

The 5' Meeting of the International Collaborative Project to Evaluate Fire Models for Nuclear

Power Plant Applications was hosted by the National Institute of Standards and Technology

(NIST), U.S. Department of Commerce and the U.S. Nuclear Regulatory Commission (NRC),

and held at NIST headquarters in Gaithersburg, Maryland on May 2 and 3, 2002. Thirty-three

participants from five countries, France, Germany, UK, Finland, and the US attended the

international meeting. Seventeen organizations including regulatory agencies, research

institutions, nuclear utilities, industry groups, professional organizations, consultants, and

academia were represented at the meeting.

The objective of the International Collaborative Project to Evaluate Fire Models for Nuclear

Power Plant Applications is to share the knowledge and resources of various organizations to

evaluate and improve the state of the art of fire models for use in nuclear power plant (NPP) fire

safety analysis. The project is divided into two phases. The objective of the first phase is to

evaluate the capabilities of current state-of-the-art fire models (empirical, zone, lumpedparameter, and computational fluid dynamic) for fire safety analysis in NPPs. The second phase

will implement beneficial improvements to current fire models that are identified in the first

phase, and extend the validation database of those models.

The 1st planning meeting of the project was held at the University of Maryland at College Park,

USA, on October 25-26, 1999. The summary of the 1st meeting and details of the objectives and

plans established for the project can be found in NUREG/CP-0170 (April 2000). The 2nd

meeting of the collaborative project was hosted by the Institut de Radioprotection et de Suret6

Nucleaire (IRSN), France and held at the IRSN offices at Fontenay-aux-Roses, France on June

19 and 20, 2000. The objective of the 2 d meeting was to discuss the definition of the V

benchmark exercise in the project for analyzing cable tray fires in nuclear power plants. The

summary of the 2nd meeting can be found in NUREG/CP-0 173 (July 2001). The 3rd meeting of

the collaborative project was hosted by the Electric Power Research Institute (EPRI) and held at

the EPRI offices in Palo Alto, California on January 14-15, 2001. The objective of the 3rd

meeting was to discuss the results of the benchmark exercise. Since the results of the 1 '

benchmark exercise were documented in NUREG-1758 (June 2002), formal proceedings of the

3rd meeting were not published. The 4' meeting of the collaborative projected was hosted by

GRS, Germany and included discussions to finalize the report of the 1 benchmark exercise. A

summary of the 4' meeting can be found in Report No. GRS-A-3106.

The purpose of the 5' meeting was mainly to discuss the preliminary results of the 2nd

benchmark exercise in the project on pool fires in large halls. The purpose of the 2nd benchmark

exercise was to challenge the limits of zone fire models by analyzing pool fires in large multilevel spaces, like in a turbine building in a nuclear power plant. A summary of the technical

discussion on the 2nd benchmark exercise is provided below. Since the meeting was co-hosted

by NIST and the NRC, opening remarks were provided by representatives of the two

organizations detailing their interests and research objectives in this topic area. Mark

vii
Cunningham, Chief of the Probabilistic Risk Analysis Branch in the Office of Nuclear

Regulatory Research, NRC described NRC's goals and plans for research to support riskinformed regulation, specifically for fire protection in nuclear power plants. James Hill, Deputy

Director of the Building and Fire Research Laboratory provided a broad overview of the mission

and programs at NIST for building and fire research. His talk was followed by a summary of

ongoing projects at the Fire Research Division at BFRL, NIST provided by Anthony Hamins.

Remy Bertrand of IRSN, France ended the opening session with a discussion of future fire

research at IRSN in France, including the selection and identification of fire scenarios and

research needs. A session was organized on the regulatory applications of fire models which

included presentations of simple analytical tools for use in the inspection process, nuclear utility

interests for the application of fire models in nuclear power plants, and the development of a fire

modeling guide for nuclear power plant applications. A summary of this session is provided

below. A session on the validation of fire models included presentations of extensive efforts by

various organizations to validate fire models. The meeting was concluded with a discussion of

future efforts in the collaborative project.

Validation and Regulatory Applications of Fire Models

Papers were presented on the regulatory application of fire models by a user in a utility, and staff

in a regulatory agency and industry research group. The papers identified the need for

technology transfer from the research community to users, and education and training of both

regulatory inspectors and plant staff. Increased dialogue between inspectors and plant staff and

use of the same tools will lead to a common understanding of the models. There is a need for

guidance on the use of models, and a good user interface for effective application of the models

to prevent misuse. Worksheets based on empirical models available from handbooks were

presented both by regulators and industry as a 1 systematic application of quantitative fire

hazard analysis for nuclear power plants. These worksheets provide a means to transition from

qualitative to quantitative inspection methods, and also serve as a design guide to support day-today operations. However, presenters and participants noted that although these empirical models

provide a good start, they should not be treated as "gospel." It is necessary to establish the

margins of uncertainty in these correlations by conducting validation exercises. These margins

can then be used to establish safety factors in fire hazard analysis methods that will lead to

acceptability of the analysis methods.

Participants also presented descriptions and validation results of a wide range of zone, lumpedparameter, and CFD models. Participants discussed and identified a need to transition from

simple to more comprehensive and accurate tools. In order to identify the right tools for various

regulatory applications, it is necessary to benchmark the different tools to develop their accuracy

for a wide range of fire scenarios.

Participants discussed and noted that any type of fire model analysis requires establishing

credible fire scenarios. Participants noted that current documents on the use of fire models in

NPP applications have not addressed this item as yet. The absence of such information is a

challenge in the current inspection process. Fire scenario definition should be identified as a

viii
priority in the research plan. Flame spread rate data in cable trays was also identified as a

priority research item. The development of a comprehensive database of mass loss rate profiles

for combustible materials in NPPs is essential for the efficient and broader application of fire

models in fire safety analysis.

Technical Results of Benchmark Exercise # 2. Part L. "Pool Fires in Large Halls

The results presented for Part I were generally quite encouraging. While the general, qualitative,

nature of the experiments had been captured in the simulations, a number of issues had arisen.

Furthermore, the parametric analysis undertaken by a number of participants had yielded useful

information. Different conclusions have been drawn on the most significant, or controlling,

parameters, that impact the results presented in Part I.

For the purpose of calculating layer height and temperature, for which most of the measurement

data had been collected, the zone model (CFAST) appeared to be fit for purpose. This was

encouraging given the complexity introduced by the roof shape, for which an 'equivalent' flat

ceiling sufficed. Analyses of the size and location of the 'infiltration' openings for case 1 and 2

indicated that the predictions were not sensitive to these parameters. This finding was supported

by zone, lumped parameter, and CFD models.

While different models were in broad agreement, participants had not always agreed on the most

sensitive parameters, i.e. what parameters were particularly critical in terms of their influence on

the final predictions. An example here was the heat losses to the walls and ceiling.

The combined effect of the choice of heat of combustion, combustion efficiency and radiative

fraction was found to be an important factor. It seems that the choice of 80% for the combined

effect of combustion efficiency and radiative fraction was not ideal, resulting in too much heat

being convected into the upper layer (and hence the predicted temperatures being higher than the

measured ones). By selecting an appropriate balance of convective heat release rate (by

modifying the combustion efficiency and/or radiative fraction) and heat losses to the boundaries,

modelers could replicate the measured layer temperature quite closely.

Finally, there was a general trend to predict lower layer depths (i.e. closer to the floor) than those

derived from the measurement data. This is perhaps a consequence of the post processing of the

thermocouple data to derive smoke layer information.

ix
Foreword

The U.S. Nuclear Regulatory Commission, in collaboration with the National Institute of

Standards and Technology (NIST), U.S. Department of Commerce, is pleased to publish the

proceedings of the 5' meeting of the International Collaborative Project to Evaluate Fire Models

for Nuclear Power Plant Applications. Since the inception of the project in 1999, the U.S. NRC

and NIST established an inter-agency memorandum of understanding and collaborated in

conducting research to provide the necessary technical data and tools to support the use of fire

models in nuclear power plant fire safety analysis. The joint sponsorship of the 5' meeting of

the project and publication of these proceedings is one product of this collaboration. As is

apparent from these proceedings, the international collaborative project is resulting in a

significant exchange of useful technical information between participants in the project. The

U.S. NRC appreciates and values the technical information provided by all participants in this

project. It would be difficult for a single organization to generate the diverse technical

information collected through such a broad collaborative effort. The U.S. NRC is pleased to be a

partner and provide its contribution to the international collaboration through its participation in

the project and publication of these proceedings.

Scott Newberry, Director 

Division of Risk Analysis anpplications

Office of Nuclear Regulatory Research

U.S. Nuclear Regulatory Commission

xi
Acknowledgments

Support for administration and audio-visual arrangements for the meeting was provided by

Wanda Duffin and Kevin McGrattan. Walter Jones and George Mulholland hosted the lunches

for the participants at the NIST executive dining room.

Xiii
Acronyms and Initialisms

BRE

CIB

CFAST

CFD

COCOSYS

EdF

EPRI

FDS

GRS

HRR

iBMB

IRSN

JASMINE

NII

NIST

NPP

NRC

PRA

VTT

WPI

Building Research Establishment

International Council for Research and Innovation in Building and Construction

Consolidated Model for Fire and Smoke Transport

Computational Fluid Dynamics

Containment Code System

Electricite de France

Electric Power Research Institute

Fire Dynamics Simulator

Gesellschaft fuer Anlagen-und Reaktorsicherheit

Heat Release Rate

Institut fuer Baustoffe, Massivbau und Brandschutz

Institut de Radioprotection et de Sfiret6 Nucleaire

Analysis of Smoke Movement in Enclosures

H. M. Nuclear Installations Inspectorate

National Institute of Standards and Technology

Nuclear Power Plant

Nuclear Regulatory Commission

Probabilistic Risk Analysis

Valtion Teknillinen Tutkimuskeskus

Worcester Polytechnic Institute

xv
1 Introduction

The objective of the International Collaborative Project to Evaluate Fire Models for Nuclear

Power Plant Applications is to share the knowledge and resources of various organizations to

evaluate and improve the state of the art of fire models for use in nuclear power plant (NPP) fire

safety analysis. The project is divided into two phases. The objective of the first phase is to

evaluate the capabilities of current state-of-the-art fire models (empirical, zone, lumpedparameter, and CFD) for fire safety analysis in NPPs. The second phase will implement

beneficial improvements to current fire models that are identified in the first phase, and extend

the validation database of those models.

The 1st planning meeting of the project was held at the University of Maryland at College Park,

USA, on October 25-26, 1999. The summary of the 1st meeting and the details of the objectives

established for the project can be found in NUREG/CP-0170 (April 2000). The 2nd meeting of

the collaborative project was hosted by the Institute for Protection and Nuclear Safety (IPSN),

France and held at the IPSN offices at Fontenay-aux-Roses, France on June 19 and 20, 2000.

The objective of the 2nd meeting was to discuss the definition of the 15 benchmark exercise in the

project. The summary of the 2nd meeting can be found in NUREG/CP-0173 (July 2001). The 3 rd

meeting of the collaborative project was hosted by the Electric Power Research Institute (EPRI)

and held at the EPRI offices in Palo Alto, California on January 14-15, 2001. The objective of

the 3 rd meeting was to discuss the results of the 1st benchmark exercise. Since the results of the

ISt benchmark exercise were documented in NUREG-1758 (June 2002), formal proceedings of

the 3 rd meeting were not published. The 4 meeting of the collaborative projected was hosted by

GRS, Germany and included discussions to finalize the report of the 1 benchmark exercise. A

summary of the 4t meeting can be found in Report No. GRS-A-3106.

The 5 Meeting of the International Collaborative Project to Evaluate Fire Models for Nuclear

Power Plant Applications was hosted by the National Institute of Standards and Technology

(NIST), U.S. Department of Commerce and held at NIST headquarters at Gaithersburg,

Maryland on May 2 and 3, 2002. The organizing Committee for the meeting included Moni Dey

from the U.S. Nuclear Regulatory Commission (U.S. NRC), and Anthony Harnins from NIST.

The following thirty three participants from five countries attended the international meeting:

1. Stewart Miles, BRE, UK

2. Olavi Keski-Rahkonen, VTT, Finland

3. Remy Bertrand, IPSN, France

4. Chantal Casselman, IPSN, France

5. Marina Roewekamp, GRS, Germany

6. Walter Klein-Hessling, GRS, Germany

7. Doug Brandes, Duke Power Co., USA

8. Bijan Najafi, SAIC/EPRI, USA

9. Francisco Joglar-Billoch, SAIC/EPRI, USA

10. Doug Beller, NFPA, USA

11. Jonathan Barnett, WPI, USA

1
12. Fred Mowrer, UMD, USA

13. Boro Malinovic, Fauske Associates, USA

14. Marty Plys, Fauske Associates, USA

15. Alan Coutts, Westinghouse, USA

16. Amber Martin, Westinghouse, USA

17. Fred Emerson, NEI

18. Phil DiNenno, Hughes Associates/NEI, USA

19. Jim Hill, NIST, USA

20. Anthony Hamins, NIST, USA

21. Kevin McGrattan, NIST, USA

22. Walter Jones, NIST, USA

23. George Mulholland, NIST, USA

24. Jason Floyd, NIST, USA

25. Louis Gritzo, SNL, USA

26. Steve Nowlen, SNL, USA

27. Mark Cunningham, NRC, USA

28. Moni Dey, NRC, USA

29. JS Hyslop, NRC, USA

30. Naeem Iqbal, NRC, USA

31. Mark Salley, NRC, USA

32. Chris Bajwa, NRC, USA

33. Sharon Steele, NRC, USA

The purpose of the 5t meeting was to discuss the preliminary results of the 1st part of the 2nd

benchmark exercise in the project on pool fires in large halls. The specification of the 2nd part of

the exercised was also discussed. Other topics discussed at the meeting included the regulatory

application and validation of fire models. The full agenda of the 5t' meeting is included in

Appendix A.

2
2 Background

The first task of the collaborative project was to undertake a benchmark exercise to evaluate the

current capability of fire models to analyze the hazard associated with cable tray fires of

redundant safety systems in nuclear power plants. These systems are required to shutdown the

reactor during an emergency, and when located inside the same compartment must be separated

by a specified distance to ensure that a fire in one system does not cause the other to fail also.

The exercise involved a series of hypothetical scenarios to predict cable damage inside an

emergency switchgear room, and were fairly tightly specified in respect of the input and

modeling parameters to be used. Due to the size of the room and the nature of the fire scenarios,

the differences in the conclusions obtained using the various fire models were not significant.

Target cable damage was predicted to be unlikely in almost all cases studied. A summary of the

main results, findings and conclusions is included in NUREG-1758 (June 2002).

This section summarizes the second benchmark exercise. The main objectives taken into

consideration when selecting the second benchmark exercise were:

* To examine scenario(s) that provide a harder test for zone models, in particular with

respect to fire spread in large volumes representative of, say, a turbine hall.

* If possible, to make use of experimental data to fulfil the requirement of more thoroughly

testing the predictive capability of both zone and CFD fire models. Again, the emphasis

when selecting scenarios was on large smoke filling volumes.

Benchmark Exercise # 2 is divided into two parts. For the first part there are experimental

measurements of temperature and velocity against which model predictions can be compared.

The second part extends the scope of the exercise to examine the consequence of larger fires, but

for which there are no experimental measurements against which to compare.

Part I includes three cases, based on a series of full-scale experiments inside a test hall with

dimensions 19 m high by 27 m long by 14 m wide (i.e. floor area 378 m2). Each case involves a

single fire (2 - 4 MW), and for which there are experimental measurements of gas temperature

and doorway velocity. The height of a turbine hall within an NPP (c. 25 in) is similar to that of

the test hall although it is acknowledged that the area of a turbine hall (c. 3500 M2 ) is much

greater. However, the test hall is one of the largest enclosures for which fire test data is

available for comparison with model predictions. The preliminary results of Part I were

presented and discussed at the 5 meeting.

Part II includes three additional cases for which experimental measurements do not exist, but

extend the scope of the benchmark exercise to examine the effect of a bigger fire and larger floor

area representative of a hydrocarbon pool fire in a real turbine hall. These are optional cases for

participants to investigate if time and resources allow. The specification of Part II was discussed

at the 5h meeting.

Although most input parameters are defined, Benchmark Exercise # 2 does in a few respects

3
involve a greater degree of user judgement in setting up the problem compared to the first

benchmark exercise. This applies in particular to the treatment of the sloping roof (with zone

models) in Part I. Appendix B includes the full specification document for Benchmark Exercise

#2.

4
3 Meeting Summary

The following provides a summary of the main topics discussed at the meeting, the 2nd

benchmark exercise, and the validation and regulatory application of fire models. Summary

papers submitted for the proceedings and slides used by the presenters are included in

Appendices C and D, respectively.

3.1 Benchmark Exercise # 2, "Pool Fires in Large Halls"

Summary

Session IV was devoted to the second benchmark exercise (Fire in a Large Hall). This has been

selected to challenge fire models in respect to issues not addressed in the first exercise, e.g.

effects of fire in a large volume representative of, say, a turbine hall. Furthermore, it includes

some scenarios for which there are experimental measurements, allowing comparisons to be

undertaken.

Benchmark Exercise # 2 is divided into two parts. For the first part there are experimental

measurements of temperature against which model predictions can be compared. The second part

extends the scope of the exercise to examine the consequence of larger fires, but for which there

are no experimental measurements to compare against.

The session was devoted mainly to presentations and discussions on simulations of Part I, where

various participants had made comparisons between predicted and measured data. This was

followed by a discussion of the format for Part II of the benchmark exercise, so that the problem

definition could be finalized before participants undertook simulations.

Benchmark Exercise # 2 - Part I

S. Miles introduced Part I at the start of the session. It includes three cases, based on a series of

full-scale experiments inside a test hall with dimensions 19 m high by 27 m long by 14 m wide.

Each case involves a single fire, in the range 2 to 4 MW, and for which there are experimental

measurements of gas temperatures at various locations inside the hall, in particular at the

location of three vertical thermocouple trees.

The problem specification included in Appendix B contains full details of the tests, and the

requirements for the numerical simulations. It was released in conjunction with a summary of the

measurement data against which to compare predictions, and so Part I is therefore an informed

study rather than a blind simulation exercise. Nevertheless, participants have been invited to

make quantitative comparisons between predictions and measurements, and to draw conclusions

where possible.

Six presentations were made at the meeting, covering ten sets of predictions, including three

examples of CFAST, two of FDS, two of JASMINE and one each of COCOSYS, HADCRT and

CFX.

5
Presentations

Jonathan Barnett - Class Exercise using CFAST, JASMINE and FDS

The presentation was made by J Barnett on behalf of nine students studying performance-based

fire design as part of an undergraduate course at Worcester Polytechnic Institute. Most students

had some experience in the fire protection industry. However, prior to the exercise they had only

had limited experience of zone models, and none had any CFD experience.

The students had been divided into three groups, one group using FDS, one group using

JASMINE (via the JOSEFINE user interface) and one group using CFAST. The presentation

focussed more on general observations rather than detailed comparisons. With all three models

the students had found the sloping roof a challenge. For the zone model (CFAST) an equivalent

flat ceiling had been specified. For both CFD models they had found setting up the sloping roof

to be time consuming. Probably the biggest 'complaint' of the CFD models was the long

simulation times compared to zone models, making sensitivity analysis difficult. Another issue

was in calculating layer heights and temperatures from CFD data.

Two options had been investigated for setting the height of the equivalent flat ceiling in CFAST;

conserving the enclosure volume and conserving the enclosure surface area. However, it was

found that the choice had no significant effect on the results. The students had been unsuccessful

in specifying mechanical exhaust ventilation for case 3.

Predictions for gas temperature were considered to appear reasonable for all models. Given that

they had used the models with little, or no, prior fire modelling experience and were left in the

main unsupervised, the outcome of the exercise was quite promising. However, the students had

found the models quite difficult to use, and stressed the need for good guidance on their use.

Walter Klein-Hessling - COCOSYS (lumped parameter) and CFX-4 (CFD)

W Klein-Hessling presented work that he had undertaken with the lumped parameter model

COCOSYS and that his colleague, W Heitsch, had performed with the CFD model CFX-4. Most

work had been undertaken with COCOSYS at this stage.

COCOSYS had been set up with approximately 500 (lumped parameter) control volumes, with

individual ones located the thermocouple locations so that a detailed comparison against those

measurements could be made. The COCOSYS simulations had taken about three hours for each

case.

Reasonable agreement between predicted and measured temperatures at the three thermocouple

trees had been achieved with COCOSYS once the combustion efficiency had been reduced by a

further 40%. In the specification document a plume radiative fraction of 20% had been

suggested, which had been equated to a reduced combustion efficiency. Another useful finding

from the COCOSYS study was that varying the location of the infiltration openings for case 1

and 2 had little effect on the results. Heat loss to the walls and ceiling had been varied, but while

6
this modified the gas temperatures by up to 20'C, this was less than the effect produced by

reducing the combustion efficiency.

COCOSYS had under predicted the plume temperature, which is a consequence of there being

no plume model and the control volumes above the fire being relatively large (compared to those

typically used in CFD). Furthermore, the spread in temperatures at the thermocouple column

locations was greater in the COCOSYS results than in the measurements, which may be a

consequence of not solving for momentum conservation. It was suggested that the COCOSYS

pyrolysis model could have been used, which predicts the mass release rate of fuel. However,

additional information about the fire source would have been required.

Only preliminary simulations had been performed with CFX. However, the temperature

predictions were currently too high. Furthermore, numerical stability problems had been

encountered, especially with case 3 (with mechanical ventilation). The problem of generating

layer interface and temperature information from a CFD simulation was raised. The CFX

simulations had taken about one week each.

A general remark was made that the use of a fixed convective heat transfer coefficient (10 J s-1

m-2 K-1) was too simplistic.

Amber Martin - CFAST (zone)

This presentation was from a practicing consultant's perspective. CFAST version 3.1.6 had been

used to simulate Part I. As the presenter had not received the experimental summary data, the

simulations had been performed blind. It was encouraging to see that the CFAST predictions for

layer height and temperature were in line with those produced by the other participants. Upper

layer temperatures were quite close to the measurements, and the predicted layer height

descended to a lower value than that indicated by the measurement data. As for the other CFAST

participants, an equivalent flat ceiling had been modeled (conserving enclosure volume).

Boro Malinovic - HADCRT (lumped parameter)

This presentation covered the second of the lumped parameter models. HADCRT was developed

initially for explosions and other accidents, but is being extended to include fire modelling. In

contrast to the COCOSYS simulations, relatively few 'junctions' were employed and so the

modelling was more akin to that of a zone model. Consequently, simulations took only a few

minutes.

The upper layer temperature predictions were quite close to the experimental values but the layer

was predicted to descend closer to the floor. Although radiation had been ignored in the

simulations reported, about 20 to 25 % of the heat was transferred to the boundaries (by

convection).

It was suggested that a parametric analysis of the effect of varying the size and location of the

infiltration openings for case 1 and 2 be performed, as this may be important. In particular, it

7
may influence the lower layer temperature.

Kevin McGrattan - FDS (CFD)

The FDS simulations were undertaken as specified, except that 35% of the heat release rate was

assigned to plume radiation (instead of 20%). FDS version 2 was used, with five mesh blocks

(one at the plume with a mesh resolution of 10 cm and four in the rest of the hall with a

resolution of 40 cm). A total of approximately 200,000 grid cells were used in the simulations.

Using this grid, good agreement between predicted and measured temperatures at the three

thermocouple columns was demonstrated.

There was some discrepancy in the plume temperatures, particularly at the lower thermocouple

location (about 100'C discrepancy for case 1). This was attributed to limitations of the

combustion model, and it was suggested also that if the plume had leaned slightly in the

experiments then this feature would most likely be missed in the simulation, which would still

'pick up' the hot temperature on the plume centre-line. Better plume temperature agreement was

achieved in case 2 and 3 (with the larger fire size), which was attributed to there being more grid

cells across the width of the plume compared to case 1.

Earlier simulations had been undertaken with a single mesh block, resulting in a coarser grid at

the plume. The temperature agreement was not as good with this grid, with the predicted values

being too high. This was attributed to the grid size being too great, with the result that the air

entrainment was under-predicted and thus the ceiling layer was then too hot. It was stressed that

grid size in the plume was critical in the LES approach, and that 6 to 8 grid cells across the

diameter of the fire source were required. This led onto a discussion on how engineers should be

guided on this, and also on related numerical and modeling issues.

Stewart Miles - JASMINE (CFD) and CFAST (zone)

This presentation covered simulations using JASMINE and CFAST (used in conjunction with

the FAST graphical interface). A sensitivity analysis had been performed with CFAST on a

number of parameters, in particular the heat losses to the boundaries and the size and location of

the infiltration openings for case 1 and 2. A more limited sensitivity analysis had been

undertaken with JASMINE, examining again the boundary heat losses and the infiltration

openings. A grid sensitivity analysis had been performed with JASMINE.

In common with the approach adopted by other participants, CFAST was run with a flat ceiling

with a height set to conserve the volume of the enclosure for most simulations. Sensitivity to

ceiling height had been investigated. 'Baseline' CFAST simulations were performed using the

specified combination of sheet metal and mineral wool. However, to investigate the sensitivity to

boundary heat loss, simulations had been performed with metal only, mineral wool only and

non-conducting (adiabatic) surfaces. For case 1 and 2 the sensitivity to the size and location of

the 'infiltration' openings had been investigated. Here the original 0.5 m2 openings were

replaced first by 0.01 m2 openings and then by two large (16 m2) openings. The effect of

increasing/decreasing the height of the openings (above the floor) had been studied too.

8
The CFD (JASMINE) simulations had been performed using a numerical mesh of approximately

130,000 elements. A mesh resolution sensitivity study, using a mesh with eight times the number

of elements, was reported. Heat losses to the boundaries had been modeled using a thermal

penetration model, assuming only the mineral wool material. The effect of increasing the

boundary heat losses (by modifying the thermal properties of the material) had been investigated.

The presentation reported that probably the most important finding, demonstrated by both the

zone and CFD models, was the sensitivity of the gas temperatures to the conduction losses at the

walls and ceiling. In the CFAST simulations the closest agreement with measurement was

obtained by using either a sheet metal and mineral wool two-layer combination or by using the

sheet metal alone. In the JASMINE simulations closer agreement with measurement was

obtained when the conduction losses were increased. It was suggested that the conduction into

the steel might be important. The smoke layer height, however, seemed to be less sensitive to the

boundary conduction loss calculation.

The CFAST study indicated that while the upper layer temperature is sensitive to the choice of

ceiling height, the layer height is sensitive only during the initial stage of the fire. Both the zone

model and CFD simulations had indicated that the exact choice of 'infiltration' openings in case

1 and 2 was not critical.

Reasonable agreement has been shown between measured plume temperatures and those

predicted in the JASMINE simulations. The mesh refinement study had indicated some

sensitivity to this parameter, with the finer mesh producing results closer to those measured.

Summarizing Remarks

The results presented for Part I were generally quite encouraging. While the general, qualitative,

nature of the experiments had been captured in the simulations, a number of issues had arisen.

Furthermore, the parametric analysis undertaken by a number of participants had yielded useful

information. Different conclusions have been drawn on the most significant, or controlling,

parameters.

For the purpose of calculating layer height and temperature, for which most of the measurement

data had been collected, the zone model (CFAST) appeared to be fit for purpose. This was

encouraging given the complexity introduced by the roof shape, for which an 'equivalent' flat

ceiling sufficed. Analyses of the size and location of the 'infiltration' openings for case 1 and 2

indicated that the predictions were not sensitive to these parameters. This finding was supported

by zone, lumped parameter and CFD models.

While different models were in broad agreement, participants had not always agreed on the most

sensitive parameters, i.e. what parameters were particularly critical in terms of their influence on

the final predictions. An example here was the heat losses to the walls and ceiling.

The combined effect of the choice of heat of combustion, combustion efficiency and radiative

fraction was found to be an important factor. It seems that the choice of 80% for the combined

9
effect of combustion efficiency and radiative fraction was not ideal, resulting in too much heat

being convected into the upper layer (and hence the predicted temperatures being higher than the

measured ones). By selecting an appropriate balance of convective heat release rate (by

modifying the combustion efficiency and/or radiative fraction) and heat losses to the boundaries,

modelers could replicate the measured layer temperature quite closely.

Finally, there was a general trend to predict lower layer depths (i.e. closer to the floor) than those

derived from the measurement data. This is perhaps a consequence of the post processing of the

thermocouple data to derive smoke layer information.

Benchmark Exercise # 2 - Part II

Part II is a 'hypothetical' example for which there are no experimental measurements. However,

the dimensions of the building are greater than in Part I, and have been selected to more closely

represent a turbine hall.

The current specification for Part II (as at the time of the meeting) was summarized by S Miles.

The fire source was representative of a large hydrocarbon pool fire. 'Target' cables and beams

had been included, for which the likelihood of thermal damage was to be estimated. Although

the building geometry was rectangular, in some of scenario cases there was the added complexity

of an internal ceiling, effectively dividing the space into two connected compartments. There

then followed a general discussion on what, if any, modifications should be made before

participants proceeded to model the cases.

Modelers seemed keen to undertake simulations of Part IL. However, while some participants

wished for a bigger fire (> 200 MW), others wanted a smaller one. It was decided to keep the fire

size as it was currently specified (i.e. growing to about 70 MW). The other main changes that

were agreed or suggested were:To reduce the number of cases to be modelled to three.

* To include the internal ceiling, dividing the hall into a lower and upper deck, in all cases.

* To introduce a second opening in the internal ceiling.

* To increase the mechanical extraction rate to 24 m3s-1 and 120 m3s-1 for the cases where

this is included.

There was an interest in the ability of models to predict the flow distribution through the hatch

opening(s), which might be quite complex. It was agreed to add the calculation of net up/down

mass and heat fluxes through the opening(s) to the list of predicated variables.

Note that following the meeting the specification for Part II was revised and presented on the

web pages of the collaborative project for comment. The final specification was made available

to participants on 5th June 2002.

10
3.2 Validation and Regulatory Applications of Fire Models

Three papers were presented on the regulatory application of fire models by a user in a utility,

and staff in a regulatory agency and industry research group. The papers identified the need for

technology transfer from the research community to users, and education and training of both

regulatory inspectors and plant staff. Increased dialogue between inspectors and plant staff and

use of the same tools will lead to a common understanding of the models. There is a-need for

guidance on the use of models, and a good user interface for effective application of the models

to prevent misuse. Worksheets based on empirical models available from handbooks were

presented both by regulators and industry as a lt systematic application of quantitative fire

hazard analysis for nuclear power plants. These worksheets provide a means to transition from

qualitative to quantitative inspection methods, and also serve as a design guide to support day-today operations. However, presenters and participants noted that although these empirical models

provide a good start, they should not be treated as "gospel." It is necessary to establish the

margins of uncertainty in these correlations by conducting validation exercises. These margins

can then be used to establish safety factors in fire hazard analysis methods that will lead to

acceptability of the analysis methods.

Participants also presented descriptions and validation results of a wide range of zone, lumpedparameter, and CFD models. Participants discussed and identified a need to transition from

simple to more comprehensive and accurate tools. In order to identify the right tools for various

regulatory applications, it is necessary to benchmark the different tools to develop their accuracy

for a wide range of fire scenarios.

Participants discussed and noted that any type of fire model analysis requires establishing

credible fire scenarios. Participants noted that current documents on the use of fire models in

NPP applications have not addressed this item as yet. The absence of such information is a

challenge in the current inspection process. Fire scenario definition should be identified as a

priority in the research plan. Flame spread rate data in cable trays was also identified as a

priority research item. The development of a comprehensive database of mass loss rate profiles

for combustible materials in NPPs is essential for the efficient and broader application of fire

models in fire safety analysis.

3.3 Future Tasks and Benchmark Exercises

Session V of the meeting included presentations and discussion of proposed benchmark

exercises for the project. Participants agreed to proceed with planning of these proposed

exercises (which are summarized below) at the 6kh project meeting scheduled for October 2002.

1. Benchmark Exercise # 3, "Cable Targets in Single Compartment Fires": This

benchmark exercise will entail blind simulation of tests in a full-scale single

compartment that will be sponsored by NRC and conducted at NIST. The size of the

compartment will be representative of those in NPPs, and the fire source will be

moderate sized hydrocarbon fires. The goal of these tests is to confirm the findings

11
of Benchmark Exercise # 1 and focus on the issues that arose from that exercise,

namely, the prediction of heat flux incident on target cable trays and the thermal

response of the target.

II. Benchmark Exercise # 4, "Large Kerosene Pool Fires": This benchmark exercise will

entail blind simulation of large kerosene pool fires in a single compartment. The tests

will be sponsored by GRS and conducted at iBMB. The goal of the tests is to

develop basic data for simulating kerosene fires under different boundary conditions,

and to examine the ability to calculate the fire effects for selected scenarios. The

benchmark exercise will focus on one of the test scenarios in the program.

III. Benchmark Exercise # 5, "Flame Spread in Cable Tray Fires": This benchmark

exercise will entail simulation of cable tray fires and their effects in a single

compartment. The tests will be sponsored by GRS and conducted at iBMB. Vertical

and horizontal cable trays, different types of cables, and degree of cable preheating

will be examined in the test program. The benchmark exercise will focus on one of

the test scenarios in the program.

IV. Benchmark Exercise # 6, Target Heating in Divided Compartments: This benchmark

exercise will entail the blind simulation of tests in the compartment used in

Benchmark Exercise # 3, but divided with half walls to be more representative of

NPP compartments. The exercise will focus on the effects of the half walls on flow

and radiation shielding within the compartment. These tests will be sponsored by

NRC and conducted at NIST.

V. Benchmark Exercise # 7: This benchmark exercise will be conducted in the

compartment used for Benchmark Exercises #s 3 and 6 and focus on examining

issues that are identified in those exercises and require further examination. These

tests will be sponsored by NRC and conducted at NIST.

12
Appendix A: Agenda for Meeting
Agenda

5 th Meeting of the International Collaborative Fire Model Project

Co-sponsored by the U.S. Nuclear Regulatory Commission, and the

National Institute of Standards and Technology,

U.S. Department of Commerce

May 2-3, 2002

National Institute of Standards and Technology,

Gaithersburg, Maryland, USA

Meeting Co-chairs: Moni Dey, U.S. NRC and Anthony Hamins, NIST, USA

Meeting Location: Lecture Room E, Administration Building (101), NIST, Gaithersburg,

Maryland

May 2 2002

8:30-9:50 AM Session I: Opening Remarks and Research Programs

Session Chair: Anthony Hamins, NIST, USA

Introductions: Workshop Participants

Opening Remarks and Research Programs

1. "U.S. NRC Goals and Plans for Research to Support Risk-Informed Regulation," Mark

Cunningham, Chief, Probabilistic Risk Assessment Branch, Office of Nuclear Regulatory

Research, U.S. NRC

2. "Mission and Programs at NIST for Building and Fire Research," James Hill, Deputy

Director, Building and Fire Research Laboratory (BFRL), NIST, USA

3. "Summary of Ongoing Projects at the Fire Research Division at BFRL, NIST," Anthony

Hamins, Leader, Analysis and Prediction Group, BFRL, NIST, USA

4. "Future Fire Research at IPSN: Selection and Identification of Fire Scenarios and Research

Needs," Remy Bertrand, IPSN, France

9:50-10: 10 AM Coffee Break

A-1
10:10-1 1:40 AM Session II: Regulatory Applications of Fire Models

Discussion Leader: MoniDey, U.S. NRC

1. "First Applications of a Quantitative Fire Hazard Analysis Tool for Inspection in U.S.

Commercial Nuclear Power Plants," Naeem Lqbal and Mark Salley, U.S. NRC

2. "Risk-Informed Applications of Fire Models," Doug Brandes, Duke Power Company,

USA

3. "EPRI Fire Modeling Project: A Guide for Nuclear Power Plant Applications," Bob

Kassawara, Bijan Najafi, and Francisco Joglar-Billoch, EPRI, USA

11:40 AM - 1:00 PM Lunch

1:00 - 4:45 PM Session III: Validation of Fire Models

Discussion Leader: Anthony Hamins, NIST, USA

4. "Summary of Validation Studies for the FLAMMES Code," Chantal Casselman, IPSN,

France

5. " Zone Model Validation for Room Fire Scenarios," Olavi Keski-Rahkonen & Simo

Hostikka, VTT, Finland

6. "The Zone Fire Model, MAGIC: A Validation and Verification Principle," Bernard

Gautier, EdF, France

7. "Enhancements to the FIVE Methodology, Fred Mowrer, UMD, USA

Break

8. "Zone Modeling Theory, Applications and Certainty - the Verification and Validation of

CFAST," Walter Jones, NIST, USA

9. "CFD Simulation of a 3.5 MW Oil Pool Fire in a Nuclear Power Plant Containment

Building Using Multi-block Large Eddy Simulation," Jason Floyd, NIST, USA

10. "Verification, Validation, and Selected Applications of the VULCAN and FUEGO Fire

Field Models," Louis Gritzo, SNL, USA

4:45-5:30 PM "NIST Large Fire Facility," George Mulholland, NIST, USA

Presentation and tour of test facility.

7:30 PM No Host Dinner - Joe's Crab Shack, Kentlands, Gaithersburg

A-2
May 3. 2002

8:30 AM - 12:00 Noon Session IV Preliminary Results of Benchmark Exercise # 2,

Part I, Evaluation of Fire Models for Nuclear Facility

Applications: Pool Fires in Large Halls

Discussion Leader: Stewart Miles, BRE, UK

1. "Specification of Benchmark Exercise # 2, Part I," Stewart Miles, BRE, UK

Preliminary Results

Presenter

2. Walter Klein-Hessling, GRS, Germany

Code Exercised

COCOSYS (lumped

parameter)

3. Mathias Heitsch, GRS, Germany CFX (CFD)

4. Jonathan Barnett, WPI, USA WPI Class Exercise

5. Amber Martin and Alan Coutts, Westinghouse, USA CFAST (zone model)

6. Boro Malinovic, Fauske Associates, USA HADCRT (lumped paramet.

12:00-1:00 PM Lunch

1:00-2:30 PM Session IVContinued: Benchmark Exercise #2

Discussion Leader: Stewart Miles, BRE, UK

7. Kevin McGrattan, NIST, USA FDS (CFD)

8. Stewart Miles, BRE, UK JASMINE (CFD), CFAST

9. "Proposal for Part II of Benchmark Exercise # 2, Stewart Miles, BRE, UK

10. Comments on Proposal for Part II of Benchmark Exercise # 2, Workshop Participants

2:30-2:45 PM Break

2:45-4:00 PM Session V: Future Tasks and Benchmark Exercises

Discussion Leader: Moni Dey, U.S. NRC

1. "Detector Response Modeling," Doug Beller, NFPA, USA

2. "A New Model for the Time Lag of Smoke Detectors," Olavi Keski-Rahkonen, VTT,

Finland

er)

A-3
3. "Proposed Benchmark Exercise for Cable Fire Tests in NPP-Type Compartments,"

Marina Rowekamp, GRS, Germany

4. "Proposed Benchmark Exercise for Kerosene Pool Fire Tests in Containment Building,"

Marina Rowekamp, GRS, Germany

5. "Challenges in use of State-of-the-Art Fire Modeling Tools in Nuclear Power Plant

Applications," Bob Kassawara, Bijan Najafi, and Francisco Joglar-Billoch, EPRI,

USA

6. "NRC Plans for Fire Tests for Model Benchmark Exercises," Moni Dey, U.S. NRC

4:00-5:00 PM Session VI: Task Scheduling and Project Management

Discussion Leader: Moni Dey, U.S. NRC

5:00 PM Workshop Concludes

5:00-5:30 PM Optional Tour of NiIST Fire Detector Laboratory

All papers are allotted 20 minutes for presentation and 5 minutes for discussion.

A-4
Appendix B: Specification of Benchmark Exercise # 2
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications

Specification for Benchmark Exercise # 2

Fire in a Large Hall

Issue 1 - February 2002

Introduction

In October 1999 the U.S. Nuclear Regulatory Commission and the Society of Fire Protection

Engineers organised a planning meeting of international experts and practitioners of fire

models to discuss the evaluation of numerical fire models for nuclear power plant applications

[1]. Following this meeting an international collaborative project was set up with a view to

sharing knowledge and resources from various organisations and to evaluate and improve the

state of the fire modelling methods and tools for use in nuclear power plant fire safety.

The first task of the collaborative project was to undertake a benchmark exercise to evaluate

the current capability of fire models to analyse the hazard associated with cable tray fires of

redundant safety systems in nuclear power plants. These systems are required to shutdown

the reactor during an emergency, and when located inside the same compartment must be

separated by a specified distance to ensure that a fire in one system does not cause the other

to fail also. The exercise involved a series of hypothetical scenarios to predict cable damage

inside an emergency switchgear room, and were fairly tightly specified in respect of the input

and modelling parameters to be used. Results and analyses were presented at a meeting at

EPRI, California, in January 2001. Due to the size of the room and the nature of the fire

scenarios, the differences in the conclusions obtained using the various fire models were not

significant. Target cable damage was predicted to be unlikely in almost all cases studied.

This document defines the second benchmark exercise. It has been selected to challenge fire

models in respect to issues not addressed in the first exercise, e.g. effects of fire in a large

volume representative of, say, a turbine hall. Furthermore, it includes some scenarios for

which there are unpublished experimental measurements, allowing comparisons to be

undertaken.

Objectives of Benchmark Exercise # 2

Benchmark Exercise # 1[2] focussed on an evaluation of fire models for predicting cable

damage in an emergency switchgear room. A summary of the main results, findings and

conclusions is included in the Technical Reference Report [3].

The main objectives taken into consideration when selecting the second benchmark exercise

were:

1. To examine scenario(s) that provide a harder test for zone models, in particular with

respect to fire spread in large volumes representative of, say, a turbine hall.

Specification for Benchmark Exercise # 2 B-1 February 2002
2. If possible, to make use of experimental data to fulfil the requirement of more thoroughly

testing the predictive capability of both zone and CFD fire models. Again, the emphasis

when selecting scenarios was on large smoke filling volumes.

Summary of Selected Scenarios

Benchmark Exercise # 2 is divided into two parts. For the first part there are experimental

measurements of temperature and velocity against which model predictions can be

compared. The second part extends the scope of the exercise to examine the consequence

of larger fires, but for which there are no experimental measurements against which to

compare.

Part I includes three cases, based on a series of full-scale experiments inside a test hall with

dimensions 19 m high by 27 m long by 14 m wide (i.e. floor area 378 mn2). Each case involves

a single fire (2 - 4 MM, and for which there are experimental measurements of gas

temperature and doorway velocity. The height of a turbine hall within an NPP (c. 25 m) is

similar to that of the test hall although it is acknowledged that the area of a turbine hall (c.

3500 mr) is much greater. However, the test hall is one of the largest enclosures for which

fire test data is available for comparison with model predictions.

Part II includes three additional cases for which experimental measurements do not exist, but

extend the scope of the benchmark exercise to examine the effect of a bigger fire and larger

floor area representative of a hydrocarbon pool fire in a real turbine hall. These are optional

cases for participants to investigate if time and resources allow.

Although most input parameters are defined, Benchmark Exercise #2 does in a few respects

involve a greater degree of user judgement in setting up the problem compared to the first

benchmark exercise. This applies in particular to the treatment of the sloping roof (with zone

models) in Part I.

Scheduled Activities

1. February 2002

Release final version of the problem definition for Benchmark Exercise # 2, to be made

available from the collaborative project document library, together with a summary of the

experimental measurement data analysis for the Part I cases. The released data for Part I

will include temperatures at three thermocouple tree locations, velocities in the open

doorways (case where they are open) and calculated layer height and upper layer

temperature (derived from the thermocouple measurements and a two-zone assumption).

2. February to Seotember 2002

Participants to perform simulations of Part I, and if time and resource allows, Part II.

3. 2nd/3rd May 2002 (5th proiect meeting at NISTJ

Participants invited to present any preliminary numerical predictions and analysis for Part

I at the 5th project meeting at NIST, USA. This will provide an opportunity for those

participants who have started work on Part I of the benchmark exercise to discuss their

initial results and findings.

Specification for Benchmark Exercise # 2 B-2 February 2002
4. 6h September 2002

Participants to send to BRE their 'final' numerical predictions for Parts I and 11 (if

undertaken) in either a text file or Excel spreadsheet. Participants should also provide a

brief summary of the modelling assumptions used for each case reported. Guidelines on

the information required are given in the case descriptions below.

5. October 2002 (6t proiect meeting at BRE)

BRE to present an overview of the results based on the information supplied.

Participants to present their results and findings for Parts I and 11 (if undertaken0. This will

follow a similar format to that adopted for the first benchmark exercise at the 3r project

meeting at EPRI, USA.

6. December 2002.

Draft technical reference document on the second benchmark exercise released. To be

compiled by BRE and including technical annexes from the other participants as for the

first technical reference document.

Specification for Benchmark Exercise # 2 B-3 February 2002
Part I - Large Hall Tests

Introduction

The three cases defined here are based on a series of full-scale fire tests inside a large hall.

In each case a pool of heptane burned for approximately five minutes, during which time gas

temperatures were measured at three thermocouple columns and at two thermocouple

locations directly above the fire source. In two cases the hall was nominally closed, while for

the third case a mechanical extract system was operational and two 'doorway' openings were

provided.

For each case, two tests were performed under nominally identical conditions. Performing a

repeat test allowed the variation in measured values due to changing ambient conditions (and

other factors) to be investigated. In all three cases the repeatability of the measurements was

reasonably good. The mass release rate of fuel for each of the three cases given below is the

average from the two tests for that case.

Geometry

Figure 1 shows the geometry of the hall, comprising a rectangular space with a pitched roof

structure above. A Cartesian axis system is defined, with the origin as indicated. All

dimensions are in metres. The four walls are labelled as west (x=0), east (x=27 m), south

(y=O) and north (y=13.8 n). Here the west and ast walls known collectively as the end walls

and the south and north walls as the side walls.

In cases 1 and 2 there are two open doorways, 0.8 m wide by 4 m high, one located in each

end wall. Both doorways open to the external ambient environment, and are located such that

the centre is 9.3 m from the south wall (y=9.

3 m>. The doorway openings are labelled as the

west doorway (door 1) and the east doorway (door 2).

Figure 2 shows the internal geometry of the test hall for Part I, including the location of the fire

source.

A single mechanical exhaust duct is located in the roof space, running along the centre yplane. It has a circular section with a diameter 1 m, and opens horizontally to the hall at a

distance 12 m from the floor and 10.5 m from the west wall (x=10.5 m).

Figure 2 shows the location and dimensions of two obstructions were present inside the hall

during the experiments and may have influenced the internal air movement. If included in

simulation these should be treated as simple rectangular obstructions. The small circles

indicate the location of the thermocouples and velocity probes, which are discussed below.

Figures 3, 4 and 5 contain plan, side and end views of the hall respectively, and should

further clarify the geometry and dimensions.

Participants should decide for themselves how to incorporate the roof geometry. For a zone

model it might be decided to set the (flat) ceiling height such that the volume of the hall is

preserved. Participants are free to undertake a series of simulations using alternate

strategies, and to comment on the findings.

Material properties

The walls and ceiling consist of a 1 mm (0.001 m) layer of sheet metal on top of a 0.05 m

layer of mineral wool. The floor is constructed from concrete. Table 1 presents the thermal

properties of the sheet metal, mineral wool and concrete materials.

Specification for Benchmark Exercise # 2 B 84 February 2002
Table 1 Material properties for Part I

Material Thermal properties

conductivity density specific heat

(Js 1 mK') rr I (kg m-4) (J kg7 K)

metal sheet 54 7850 425

mineral wool 0.2 500 150.

concrete 2 2300 900

If included by the participant, the internal obstructions can be modelled as concrete

(properties as given in Table 1). However, as the choice of material properties for the internal

obstructions is not likely to have an important bearing on the numerical predictions, the

obstructions can optionally be treated as adiabatic, i.e. no heat transfer.

All surfaces are assumed to have an emissivity of 0.95, i.e. almost black body, and a

convective heat transfer coefficient of 10 J s7' m-2 K.

Ambient conditions

Ambient pressure and temperature are 101300 N rf 2 and 20 C respectively.

Ventilation conditions

Mechanical exhaust ventilation is operational for one case, with a constant volume flowrate of

I11 mns-1drawn through the 1 m diameter exhaust duct. For this case there are two doorway

openings as described above.

For the other two cases the mechanical exhaust system does not operate and the doors are

closed. Ventilation is restricted to infiltration through the building envelope. Exact information

on air infiltration during these tests is not available. However, following discussions with the

scientists involved in the experiments, it is recommended that air infiltration be modelled by

including four small, square openings to the outside ambient environment, each opening

having an area 0.5 n9. For the purpose of the benchmark exercise it is suggested that two

openings be located in the east wall, one at floor level and 12 m above the floor, and two at

the opposite end of the hall in the west wall. Table 2 shows the co-ordinates of the centre of

the four openings.

Note that air infiltration should be ignored in the two cases with mechanical ventilation and

doors open.

Specification for Benchmark Exercise # 2 B-5 February 2002
Table 2 Openings to simulate effect of air infiltration in Part I

Opening Co-ordinates of centre

(0.707m x 0.707m) X y Z

(m) (m) (m)

1 0 6.9 0.35'

2 0 6.9 12

3 27 6.9 0.35a

4 27 6.9 12

4

4

Fire Source

A single fire source was used in each test, its centre located 16 m from the west wall and 7.2

m from the south wall (x=16 m, y=7.2 m) as indicated in Figure 2. For all tests heptane was

burned on top of water in a circular, steel tray. The fuel surface was 1 m above the floor. Two

tray diameters were used, 1. 17m for one case and 1.6 m for the other two. The trays were

placed on load cells, and the mass release rate then calculated from the time derivative of the

load cell weight readings.

For the three cases defined below the fuel mass release rate (1 ) is provided as an input

parameter. The choice of combustion mechanism is left to the participant. However, it is

suggested that the fuel rate of heat release be modelled as

Qf = mhf AH, (1)

Here the heat of combustion (H 0) is taken as 44.6x106 J kg1. The recommended combustion

efficiency () value of 0.8 may be interpreted also as a radiative fraction of 0.2. For the

purpose of the benchmark exercise, it is suggested that as in the first benchmark exercise a

value of 12% be assigned to the lower oxygen limit parameter in those combustion models

that make use of it. However, participants are encouraged to investigate other values if they

believe this to be important.

Instrumentation

Data was obtained from the instrumentation described below, against which numerical

predictions can be compared:

1. Three vertical thermocouple trees, located as shown in Figure 6, on the centre y-plane at

distances 1.5 m, 6.5 m and 20.5 m from the west wall. The vertical distribution of

thermocouples, the same for all three trees, is shown in Figure 7. Individual

thermocouples are labelled as shown in Figure 7, where T2.5, for example, refers to the

fifth thermocouple on tree number 2. Each thermocouple was a 0.1 mm K-type. Note that

the readings from these thermocouples were used to calculate a layer height and upper

layer temperature as described below.

2. Two horizontal thermocouple grids centred directly above the fire source at a height of 7

m and 13 m. Both grids consisted of nine 0.5 mm K-type thermocouples arranged in a 3

by 3 array. However, for the benchmark exercise attention is focussed only at the centre

Specification for Benchmark Exercise # 2 B-6 February 2002
thermocouple at each height, directly above the centre of the fire tray. These are labelled

as TG. 1 and TG.2 in Figure 7.

3. For the case with mechanical ventilation and open doorways, a vertical column of bidirectional probes to measure gas velocity was located in each doorway opening. Each

column contained three probes located on the vertical centre-line of the opening at the

heights shown in Figure 7. Note that a positive value indicated flow from the outside to

the inside of the hall. The velocity measurements may be used to estimate the net flow of

air through the opening.

Two-layer data reduction

A two-layer zone model will predict upper and lower layer properties, and the height of the

interface separating the layers. Therefore, to make comparisons between experimental

measurements and zone model predictions, the thermocouple data must be reduced in some

way.

Participants will be provided with the measurement data for all thermocouple locations, and

will be free to make their own data reduction to generate upper/lower layer and interface

height 'measurements'. However, the method described below will be used as a 'baseline'

method and the resultant layer values will be provided along with the 'raw' measurement data.

Furthermore, participants using CFD and network models will be invited to calculate 'upper

layer' and 'lower layer temperatures and an 'interface height' for comparison against zone

model predictions. For consistency, the method described below, based on predictions of

temperature at the thermocouple tree locations, should be used. If they wish, participants

may in addition use their own methods for calculating 'upper layer' and 'lower layer'

temperatures and an 'interface height' (and should document these methods).

Layer temoerature and interface calculation

The one-dimensional analytical method presented here allows an upper layer temperature

(Tp), lower layer temperature (T,0o) and interface height (zin) to be calculated given a discrete

set of temperatures (T) at heights above floor level (z,), i=1,N.

Consider a continuous function T(z) defining temperature as a function of height z, from 0

(floor level) to H (ceiling).

ZAL

H ----------------------- --

Zint1 ----- -- - -- --- - --

z

T111. T.. T

Then, from the zone model concept and the conservation of mass, we may write

(H - Zi. JTP + zintb = I T(z)dz = I, (2)

0

Specification for Benchmark Exercise # 2 B-7 February 2002
(H - Zint + zi.t f=|T( dZ = I2 (3)

Algebra then gives

Zit T. ( I, H 2 ) (4)

Zi + - TIO -2T 0.H

Here, T, is taken as the temperature at the loviest discrete measurement location (T,) and

11X12 are calculated from the discrete data set using a quadrature rule, e.g. Simpsons Rule. T,,

is then calculated by applying the mean value theorem over the interval z=zt to z=H

H

H 1- fT(z)dz (5)

int Z 2N

In reducing the thermocouple tree data it is proposed that the average of the three values

(one from each tree) is taken at each distance above the floor.

Exercises

The three cases to be simulated are summarised below. Details of geometry, material

properties, ambient conditions, ventilation rates and instrumentation are as defined above.

The specifications given here represent the 'baseline' scenarios. Participants are invited to

perform study variations on these cases in order to gain insight into the performance of the

fire models used. However, the three 'baseline' cases should be given priority, and

furthermore case 1 should be given highest priority.

The fire source should be taken as pure heptane, located as described above. For case 1 the

pool diameter is 1.17 m while for cases 2 and 3 it is 1.6 m. Table 3 defines the fuel mass

release rate for each case at discrete times in minutes. A piecewise linear polynomial should

be assumed, i.e. interpolate linearly between the given points.

Table 4 summarises the ventilation conditions for the three cases. Natural leakage should be

modelled as described above.

Each case should be modelled for the duration of the fire, assuming the fire to have stopped

after the last entry in Table 3, i.e. 7.5 minutes of case 1, 7 minutes for case 2 and 6 minutes

for case 3.

Specification for Benchmark Exercise # 2 B-8 February 2002
Table 3 Fuel mass release rates for Part I

l

Case 1

t (min) dmt/dt (kg s-)

Case 2

t (min) dm/dt (kg s)

_ T

0 0

0.22 0.033

1.5 0.045

4.8 0.049

5.45 0.047

6.82 0.036

7.3 0

0 0

0.23 0.057

0.5 0.067

1.52 0.081

3.22 0.086

4.7 0.083

5.67 0.072

6.2 0.06

Case 3

t (min) dm/dt (kg s-1)

0 0

0.22 0.064

1.05 0.084

2.77 0.095

4.27 0.096

4.87 0.091

5.5 0.07

5.75 0

6.58 0

Table 4 Ventilation conditions for Part I

Case 1 Case 2 Case 3

doors closed doors closed doors open (0.8 m x 4m)

no mech. exhaust no mech. exhaust mech. exhaust (11 m3 s-)

natural leakage natural leakage ignore natural leakage

Reporting procedure

The reporting schedule is summarised in the Scheduled Activities above. This section

documents the format to be adopted when submitting predictions to BRE in September 2002.

Participants should submit data in either a text file or Excel spreadsheet, and also summarise

their findings and modelling assumptions.

The 'raw' prediction data at each reported time will occupy a single record (text file) or row

(spreadsheet), with each quantity (e.g. layer height) occupying one field (text file) or column

(spreadsheet). While the first field or column should be the time value, the ordering of the

remaining fields/columns is left to the participant. However, each field/column should be

clearly labelled and the units stated. Numbers may be formatted as deemed appropriate, e.g.

fixed number of decimal places, scientific notation (1.5e+2), etc. As a hypothetical example,

part of a text file format might appear as below,

Specification for Benchmark Exercise # 2 B-9 February 2002
Time(s) T1.1(C) T1.10(C) V1.1(m/s) Layer height(m)

0. 0. 0. -0.05 19.

10. 0. 0.2 -0.06 19.

30. 0.1 2.8 1.1 16.

It is suggested that results be reported at 1 O-second intervals. However, this is a guideline

only and not a formal requirement (sufficient points to produce representative graphs is the

minimum requirement).

Table 5 includes a list of suggested variables to be reported for zone and CFD models

(acknowledging that for network models the number of reported variables will be somewhere

in between). If a fire model does not output a particular variable, then the participant should

ignore it. The number of variables to be reported depends in part on the fire model, with CFD

models allowing for a greater number of outputs. Participants are free to include other

variables that they consider important.

In addition to the tabulated results, participants are asked to summarise the main modelling

assumptions and inputs used. This will include a short summary on the following topics at

least (one or two paragraphs on each topic):

* Heat release (combustion) mechanism. This could be a combustion model or a simple

heat release source term. Issues such as the lower oxygen limit should be reported.

* Radiation treatment (if included. Important issues may include the treatment radiation

transfer to solid surfaces, the absorption/emission in the gas phase and radiation from

soot plume.

* The zonal approximations used and main empirical correlations (in the case of a zone

model).

* The number of control volumes or elements (in the case of a CFD model), or equivalently

the number of network elements (in the case of a network model).

* The turbulence model (in the case of a CFD model).

* Roof geometry assumptions (this relates mainly to zone models).

Specification for Benchmark Exercise # 2 B-10 February 2002
Table 5 Reported variables for Part I

Zone CFD

Heat release rate of fire

Interface height

Upper layer temperature

Infiltration flow rate (cases I & 2)

Mass flow rate in/out door 1 (case 3)

Mass flow rate in/out door 2 (case 3)

Total heat loss rate to solid boundaries

Heat loss through mech. exhaust (case 3)

Plume temperature

Temperatures at thermocouple trees

(T1.I ,...,T1 .10,T2.1,...,T2.10,T3.1,...,T3.IO)

Temperatures at plume thermocouples

(TG1.1 &TG.2)

Infiltration flow rate (cases 1 & 2)

Mass flow rate in/out door 1 (case 3)

Mass flow rate in/out door 2 (case 3)

Velocities at the two doorways (case3)

(V1.1,...,V1.3,V2.1,...,V2.3)

Total heat loss rate to solid boundaries

Heat loss through mech. exhaust (case 3)

Interface height

(using reduction of thermocouple tree data)

Upper layer temperature

(using reduction of thermocouple tree data)

Total heat release rate

(within whole hall)

Specification for Benchmark Exercise # 2 B-11 February 2002
Part 11 - Extended NPP Scenarios

Introduction

Part II has been added as an optional extension to the benchmark exercise. It includes three

scenario cases inside a rectangular building with dimensions comparable to those of a real

turbine hall. The fire size has been chosen to produce temperatures that may be capable of

damaging equipment or cables.

As in Part I mechanical exhaust is specified in a sub-set of cases. Targets have been added

to Part II to allow the onset of damage to be studied.

Geometry

Figure 8 shows the geometry and dimensions of the building, which are comparable to those

of a real turbine hall. For the benchmark exercise there is a doorway opening in the west wall

and at the opposite location in the east wall.

Material properties

To simplify the modelling task, assume the floor, walls and ceiling to be constructed from

concrete, with the thermal properties as given in Table 1, and a thickness of 0.15 m. Again,

assume an emissivity of 0.95 and a convective heat transfer coefficient of 10 J s '-mt 2 K'.

Ambient conditions

As specified for Part I.

Ventilation conditions

Ventilation is provided in all three cases through a doorway opening in the west and east

walls as shown in Figure 8. In two cases both openings have dimensions 1 m wide by 4 m

high, while for the third case the openings are 4 m square. Figure 9 shows the location and

dimensions of the doorway opening more clearly. The dashed line indicates the location of the

larger square doorway in the third case.

In two cases there is mechanical exhaust through 12 vents at ceiling level. Each vent is

square with dimension 1 m. Figure 8 shows the location of the 12 vents.

Fire Source

For all cases, heptane is burned in a square, 4 m by 4 m, tray such that the surface of the fuel

is 1 m above the floor. The fire is located centrally inside the hall as indicated in Figure 10.

Fuel and combustion properties are as specified for Part I.

The mass release rate of the pool fire (f) grows from zero to a steady value 1.55 kg s-'

(derived from published data for heptane pool fires [4]) as follows,

m = 2 (6)

Specification for Benchmark Exercise # 2 B-12 February 2002
I

Here t is the time in seconds from the start of the fire, and a is a constant with value

5.325x0 kg s 3. This value is derived from an assumed NFPA ultra fast t-squared growing

fire [5]. Equation (6) defines the mass release rate for the first nine minutes, at which time it

reaches the steady value 1.55 kg s1 which is maintained for the next 11 minutes (giving 20

minutes total duration).

Targets

To make Part II relevant to practical applications three cable targets have been introduced,

similarly to the first benchmark exercise. Each cable is a 50 mm (0.05 m) diameter power

cable, assumed to consist entirely of PVC. The thermal properties of the cable material are

the same as in the first benchmark exercise, repeated below in Table 6.

Table 6 Material properties for cable targets

conductivity density specific heat emissivity convective htc

(J s" ' K') (kg m3) (J kg> K1) pJ S-1 m-2 K)

0.092 1710 1040 0.8 10

A structural beam target is included also. To simplify the modelling, this is approximated as a

horizontally orientated rectangular slab of steel with cross-sectional dimensions of 0. 15 m

wide and 0.006 m thick. Table 7 provides the material properties to be assumed for the steel

'beam' target, where the conductivity, density and specific heat correspond to steel (0.5%

carbon) at 20 C [6]. It is assumed for the purpose of this exercise that property values are

temperature independent. A damage temperature of 538 C is assumed.

Table 7 Material properties for 'beam' target

conductivity density specific heat emissivity convective htc

(J s 1 m61 K1) (kg m 3) (J kg1 K) (J sl m 2 K)

54 7833 465 0.8 10

Figures 9 and 10 show the locations of the three cable targets and the 'beam' target. The

cables extend the full length of the hall (x direction), and the 'beam' extends the full width (y

direction). The centre-lines of the three cables are 1 m from the south wall, and 9 m, 15 m

and 19 m above the floor respectively. The 'beam' centre-line is midway across the width of

the hall and 0.5 m below the ceiling.

Internal ceiling

For the exercises described below, an internal ceiling has been added for some cases,

effectively dividing the turbine hall into two levels. This makes the geometry more

representative of a 'real-life' situation.

It is assumed that the internal ceiling is located 10 m above ground level and again

constructed from 0.15 m thick concrete (material properties as given in Table 1). Furthermore,

there is a hatch opening with dimensions 10 m by 5 m within the internal ceiling, providing a

connection between the lower and upper levels. Figure 11 shows the location of the internal

ceiling and hatch opening.

Specification for Benchmark Exercise # 2 B-13 February 2002
Exercises

The exercises are divided into two groups of three, where there the first group (cases la, 2a

and 3a) does not include the internal ceiling (e. a single compartment), and the second

group (cases b, 2b and 3b) includes the internal ceiling (i.e. two compartments) and the

hatch opening.

The cases to be simulated are summarised below in Table 8. Note that case lb is the same

as case la but with the addition of the internal ceiling, and likewise for the other cases. Each

case lasts for 20 minutes, or until the participant decides there is no need to proceed further,

e.g. the cables and 'beam' are damaged.

Case 1 takes highest priority in both the 'a' and 'b' groups. While the cases with the internal

ceiling are perhaps the more interesting, and arguably warrant priority, it is acknowledged that

these are more complex to model and so participants are free to concentrate on the 'simpler'

single compartment cases if preferred.

Table 8 Cases for Part II

Case la Case 2a

lm x 4m doorway openings m x 4m doorway openings

no mechanical exhaust ventilation 16 m3 s1 mechanical exhaust ventilation

(divided evenly between the 8 vents)

Case 3a Cases 1 b, 2b and 3b

4m x 4m doorway openings As for cases la, 2a and 3a, but with

80 m3 s- mechanical exhaust ventilation addition of the internal ceiling partition,

(divided evenly between the 8 vents) dividing the volume into two levels

Reporting procedure

Predictions should be reported in September at the same time as for Part I.

Cases la. 2a and 3a

The format and variables for group 'a' cases (single compartment) are as for Part l, with the

following additions or amendments:

* The three vertical thermocouple trees are at the locations shown in Figure 10. These are

of relevance to CFD models, where it is requested that gas temperatures be provided at

1 -meter intervals in height (labelling the locations Tl. 1 - Ti. 19 etc similarly to that done

for Part I).

* As for Part , the gas temperature directly above the fire is requested at two locations

(CFD models), but now at heights 9 m and 19 m.

* Three doorway velocities should again be considered at 0.5 m, 1 m and 3.5 m height, on

the vertical centre line of each opening.

Specification for Benchmark Exercise # 2 B- 14 February 2002
* The total heat loss through the doorway opening should be provided if possible.

* Upper and lower layer oxygen concentration should be provided in the case of zone

models. For CFD models the oxygen concentration at the thermocouple tree locations

should be provided.

* For each cable target and the 'beam' target the following should be provided, where

possible, at each reported time:

w maximum incident flux

= maximum surface temperature

X maximum centre-line temperature

Here the maximum refers to the maximum along the length of the cable or 'beam'. If they

wish, participants may provide the values at the mid-point (i.e. at x=40 m for the cables

and y=20m for the 'beam') allowing a simpler conduction modelling approach to be used.

Participants should provide comments on the likelihood of damage to the targets, and if so at

what time into the fire the damage occurs.

Cases lb, 2b and 3b

The reporting procedure is as for the group 'a' cases above, except that the two levels should

be accounted for. This means that interface heights and upper layer temperatures should be

provided for each level (compartment). Furthermore, the transfer of mass and heat through

the hatch opening should be reported.

Where gas temperatures are reported, these should be at the same locations as for the group

'a' cases (except that there is no temperature at locations T1. 10 and T2. 10 because of the

presence of the internal ceiling, and so a blank entry should be provided for this location).

Specification for Benchmark Exercise # 2 B-15 February 2002
References

1. International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant

Applications - Summary of Planning Meeting (24th-25th October 1999, University of

Maryland, USA), NUREG/CP-0170, February 2000.

2. International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant

Applications - Benchmark Exercise # 1 - cable tray fires of redundant safety trains, 11

September 2000.

3. International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant

Applications - Technical Reference Report on Benchmark Exercise # 1, to be published.

4. Babrauskas, V. Estimating large pool fire burning rates. Fire Technology, vol. 19, pp. 251-

261, 1983.

5. NFPA 204M - Guide for Smoke and Heat Venting. National Fire Protection Association,

1985.

6. SFPE Handbook of Fire Protection Engineering, 2nd Ed., National Fire Protection

Association, 1995.

Acknowledgements

The experimental measurements for Part I were collected by VTT as part of the European

Coal and Steel Community (ECSC) project NFSC2, and are used by permission of the

executive committee, SERDEC.

Specification for Benchmark Exercise # 2 B-16 February 2002
8.9

Figure 1 Hall and doorway dimensions for Part I

Specification for Benchmark Exercise # 2 B-17 February 2002
4~~~\ o ~~exha=d-uct_ nl2

obstru c _ lll

9.4

72 1 - - 16

10.5 Xlk\

/2 ~5 7

Figure 2 Internal geometry for Part I

FebruarY 2002

sp3ecification for Benchmark Exercise B-1-8
A 18

1.21*

L

I--

4 5 1 7

obstruction I 2.8 2. obstruction 2

fire tra L

13.8

9.7

/

exhaust duct 6.9 7.2

j

V r FI V

10.5

16

-

27

Figure 3 Plan view for Part I

Specification for Benchmark Exercise # 2 B^19 February 2002
10.5

I

19

I X

.4

16

Figure 4 Side view for Part I

27

Specification for Benchmark Exercise # 2 B-20 February 2002
4 _ 4 4.9 l

l_ 'l I

[ A

T A

1.9

5.1

4

4

4

6.9

obstruction 1

doorway

obstruction 

- I Y -. *

12

9.4

2.8 7.2

8.9

-

9.7

Figure 5 End view for Part I

Specification for Benchmark Exercise # 2 B-21 February 2002
thermocouple tree 3

velocity probes

thermocouple tree 2

thermocouple tree 1

Iz

6.5 1.5 velocity prob

Figure 6 Experimental instrumentation for Part I

es

Specification for Benchmark Exercise # 2 B-22 February 2002
1 Tl.10 t- * n.10 D T3.10

1 - Tl.9 72.9 T3.9

TI.8 72.8 - T3.8

_ T.7 72.7 T3.7

2 rl.6 T2.6TG.2 1T16i 

2

- -- TI. 5725 13 T3.5

TI.4 72.4 T3.4

2 ~~~~~~~~~~~~~~~~~~TG. I

2- : T1.3 T2.3 T3.3

- \ - TJ.2 7 T2.2 7 T3.2 V2.3

T1. I 72.1 T3.1 2 

Vl.2

Vl.l

1.5

1.5

o-.s

Figure 7 Individual thermocouples and velocity probes for Part I

Specification for Benchmark Exercise # 2 B-23 February 2002
mechanical vent (Im x m square)

0>\40

t20

80

Figure 8 Geometry for Part 11

Specification for Benchmark Exercise # 2 B-24 February 2002
Figure 9 End view for Part 11

30

Specification for Benchmark Exercise # 2 B-25 February 2002
east doorway

power cable

(0.05 m diameter)

'beam target'

(0.15 x 0.006 m horizontal slab)

fire source 

(4 m x 4 m tray)

temperature profile

location T3

temperature profile

location T2

A

X

4

r

40

CL -

20

it

temperature profile

location TI

Y r ] - 4; _I

west doorway

is

'.4 - > 

10 :1

20

1

Figure 10 Plan view for Part II

Specification for Benchmark Exercise # 2 B-26 February 2002
open hatch between

lower and upper levels

(I O m x 5 m)

1< ,1~~~~~1 * ~~~~~~~35

5 7.5

Figure 11 Internal ceiling partition and hatch for Part II cases lb, 2b and 3b

Specification for Benchmark Exercise # 2 B-27 February 2002
Appendix C: Summary Papers
CONTENTS

Opening Remarks and Research Programs Page

C. "Summary of Ongoing Projects at the Fire Research Division at BFRL,

NIST," Anthony Hamins, Leader, Analysis and Prediction Group, BFRL,

NIST, USA C-1

C.2 "Future Fire Research at IRSN: Selection and Identification of Fire Scenarios

and Research Needs," Remy Bertrand, IRSN, France C-5

Regulatory Applications of Fire Models

C.3 "First Applications of a Quantitative Fire Hazard Analysis Tool for Inspection

in U.S. Commercial Nuclear Power Plants," Naeem Iqbal and Mark Salley,

U.S. NRC C-9

Validation of Fire Models

C.4 "Summary of Validation Studies for the FLAMMES Code," Chantal

Casselman, IRSN, France C-39

C.5 "Zone Model Validation for Room Fire Scenarios,"

Olavi Keski-Rahkonen & Simo Hostikka, VTT, Finland C-59

C.6 "The Zone Fire Model, MAGIC: A Validation and Verification Principle,"

Bernard Gautier, EdF, France C-73

C.7 "CFD Simulation of a 3.5 MW Oil Pool Fire in a Nuclear Power Plant

Containment Building Using Multi-Block Large Eddy Simulation,"

Jason Floyd, NIST, USA C-77

Presentation and Tour of Test Facility

C.8 'NIST Large Fire Facility," George Mulholland, NIST, USA C-81

Preliminary Results of Benchmark Exercise # 2, Part I, Evaluation of Fire

Models for Nuclear Facility Applications

C.9 Walter Klein-Hessling, GRS, Germany - COCOSYS (lumped parameter)

& CFX (CFD) C-85

C.10 Jonathan Barnett, WPI, USA - WPI Class Exercise C-117

C-iii
C. 1 Amber Martin and Alan Coutts, Westinghouse, USA - CFAST (zone model) C-155

C. 12 Kevin McGrattan, NIST, USA - FDS (CFD) C-157

C.13 Stewart Miles, BRE, UK - JASMINE (CFD), CFAST C-161

Future Tasks and Benchmark Exercises

C.14 "Detector Response Modeling," Doug Belier, NFPA, USA C-165

C. 15 "A New Model for the Time Lag of Smoke Detectors,"

Olavi Keski-Rahkonen, VTT, Finland C-171

C-iv
FIRE SAFETY RESEARCH AT NIST

Anthony Hamins

Building and Fire Research Laboratory (http://www.bfrl.nist.gov/)

National Institute of Standards and Technology

Gaithersburg, MD 20899

The Fire Research Division is one of four Divisions in the Building and Fire Research

Laboratory (BFRL) at the National Institute of Standards and Technology (NIST). The

Division is composed of approximately 58 full time employees, 25 Guest Scientists and

several post-doctoral associates. The technical background of the staff includes

engineering, mathematics, chemistry, and physics. The Fire Research Division Budget in

2002 was approximately $13 M, with half of the support coming from government

agencies and private industry. The goal of Fire Loss Reduction is one of four technical

research areas in BFRL. The intent of this research is to provide engineered fire safety

for people, products, facilities and enhanced firefighter effectiveness. The goal is broken

into the four component programs described below.

The objective of the first component program is to eliminate the risk of flashover costeffectively by enabling 1) new/improved materials whose fire resistance does not

negatively impact performance, cost, or the environment; 2) early and certain fire and

environment sensing; and 3) automatic fire suppression technologies compatible with

occupants and the environment. Flashover is the dramatic and sudden transition from a

relatively small, slowly developing fire to a much larger and dangerous fire in which all

flammable surfaces within the enclosure are involved. Flashover is generally

accompanied by a significant increase in the heat release rate, extension of flames out

open doors and windows, and a dramatic increase in the production of toxic fire products.

Fire statistics do not report directly the occurrence of flashover. Estimates based on the

extent of fire damage indicate that roughly 30 % of reported fires transition to flashover

and that these were responsible for 80 % of fires deaths and property damage in buildings

in 1999. Reducing the risk of flashover offers an opportunity to significantly reduce the

high human and property costs of fire. Means exist to prevent flashover: e.g., by having a

fire fighter always on the scene, by installing sprinklers, or by limiting the contents of the

room.

The problem is that these means of prevention lack public acceptance because they are

not affordable, reliable, flexible, and/or predictable. Standard test methods are generally

not applicable to new technologies, and models for fire growth on realistic objects do not

yet exist. The lack of effective fire spread and growth models is recognized as a major

obstacle to the implementation of performance-based codes. A major impediment to

efforts to reduce the risk of flashover is insufficient understanding of fire growth and

spread on room contents. The unavailability of appropriate fire growth and spread models

is a serious roadblock to the implementation of performance-based fire standards. A

substantial effort is being undertaken to improve the experimental and theoretical

understanding of fire growth and spread within enclosures, with the goal of developing a

modeling capability for real-world room contents that can be reliably used for fire safety
engineering, product design, and materials assessment. BFRL has made significant

progress in cost-effective approaches that reduce the flammability of polymers while

improving or maintaining physical characteristics. Introduction of these materials into the

market will accelerate fire safety. Active measures to limit fire growth require reliable

early fire detection and effective suppression approaches. As an example, elimination of

false alarms would allow detector systems to be wired directly to the fire fighting service,

which, in turn, would reduce the response time to a fire. Directed research designed to

enhance fire detector sensitivity while reducing the number of false alarms and to

improve suppression effectiveness are being carried out. Component projects include:

* Real-scale specification and testing

* Flame radiation

* Early, fault-free detection

* Flammability measures for electronic equipment

* Micro-scale high throughput optimization of flame retarded polymers

* Bench-scale high throughput flame retardancy measures

The objective of the second component program is to enhance fire fighter safety and

effectiveness through research and help achieve a 50% reduction in line-of-duty fatalities

and burn injuries in the United States by 2012. Fire fighting operations proceed with very

limited information about the extent of fire involvement, structure safety, hazards, and

even the location of fire fighters. To be safer and more effective, incident commanders

and fire fighters need access to reliable and timely information regarding fire conditions,

developing hazards, and the location and condition of resources. Efforts are underway to

explore new technology for protective clothing, wireless transfer of information from fire

alarm systems, evaluation of performance of thermal imagers and exploring the use of

thermal imagers for hazard sensing, acoustic sensing of weak roof structures, and

capabilities of durable agents to protect structures from external fires. Component

projects are:

* Developing a heat transfer model for fire fighter protective clothing under wet and

dry conditions with associated material property database, which will be assembled

into an effective training tool and software to assist in design.

* Working with a fire alarm manufacturers and the BFRL effort in Cybernetic

Buildings, wireless means to deliver timely emergency information about conditions

inside of buildings and predictions of developing hazards to first responders before

they arrive at the scene is being demonstrated.

* The capabilities and limitations of the current generation of thermal imagers.

* A fundamentally based computational model is being developed to predict major

features of the interaction of structures with wind-driven fires utilizing FDS.

* The capabilities of acoustic sensing to determine weakness in roof structures.

* Nano-particles added to polymer gels used to protect external structures against fire

have been shown in laboratory scale experiments to greatly increase the durability of

the gel. Based upon work completed last year in a grant, a standard method to

determine the performance in full scale will be investigated to allow durable agents

with different nano-particle formulations o be evaluated.

* To aid the fire services in keeping abreast of developments in research, information

on fire service related research is being distributed electronically.

C-2
The objective of the third component program is to lead the world in fire

measurement and predictive methods, enabling engineered fire safety for people,

products, facilities, and first responders. Engineering correlations developed through

fire testing over the past 25 years have improved fire codes and technologies in the

U.S. and produced a slow decline in the number of deaths and injuries due to

unwanted fires; however, the total economic burden of fire in the U.S. continues to

rise. To counteract these losses, new fire safety technologies and performance-based

codes are needed that can only be achieved by a higher level of understanding of the

dynamics of fire, and more certain measurement methods. Component projects

include:

* basic research on the physics of fire to improve our knowledge and capabilities in

quantitative methods in heat release rate, heat flux (including spectral and total

radiation), room flows, soot/smoke, and water sprays.

* advanced instrumentation with emphasis on measurement accuracy, precision,

and interpretation of measurements through models and analysis

* mass and heat transport phenomena involving gas phase and condensed phase

processes and their interaction

* gas phase model enhancement - radiation submodel, boundary layer submodel,

water spray submodel, flow boundary sensitivity, experimental validation

* combustion submodel development - pyrolysis submodel, soot

formation/destruction submodel, experimental validation

* building structure fire model enhancement - real-scale fire validating

demonstrations, HVAC/smoke flows

* expanded numerical simulations and computational fluid dynamics models of

transport processes to encompass higher accuracy radiation, droplet and sprays

models and semi-empirical sub-models of phenomena at the fuel/flame interface

* a Large Fire Laboratory (LFL) with advanced measurement capabilities that

promote the understanding of full and reduced-scale fire phenomena

* reference data for model input against which predictions can be compared and

validated and made available electronically to the fire community

* tools and knowledge that enable the implementation of performance based fire

codes, allow assessment of key test methods and address international barriers to

standards and the role of uncertainty in regulations.

* transfer of BFRL research results to industry as well as to organizations that

create fire standards and codes.

* guidance to U.S. fire testing laboratories to identify and address research needs.

* FRIS as the source of easily-accessible fire information and data.

The objective of the fourth component program is to investigate the building

construction, the materials used, and the technical conditions that combined to cause

the World Trade Center (WTC) disaster. This work is under planning and will serve

as the basis for improvements in the way buildings are designed, constructed, and

used; improved tools, guidance for industry and safety officials, revisions to codes

and standards, and improved public safety.

C-3
- 1 -

Future Fire Research in IRSN

R. BERTRAND

Institut de Radioprotection et de SOretd NucIaire (IRSN)

This presentation indicates first the IRSN strategy related to the fire research. Then the

dominant fire scenarios that can occur in the French NPP and that need data from

research to be assessed are presented. At last, IRSN needs in fire research are indicated.

Strategy of IRSN in fire research: The axes of research are mainly defined according to

the safety assessment issues. The tight connection between expertise and research

inside IRSN as well as the dialogue between utilities (such as COGEMA) and IRSN allow

to fix clearly the priorities and the purposes of the research programs.

The research is divided into two complementary parts : experimental tests and modelling.

The strong connection between the experiments and the modelling allows to develop and

to assess the computer codes used to realise fire safety assessment. Two modelling

approaches are developed: a simplified and empirical approach for fast and global safety

assessment and a more detailed approach for more precise assessments in specific

complex configurations. The experimental work is also composed of two parts: rather

global, full scale, representative tests for getting direct information on specific

configurations or equipments (the knowledge gained from this applied research can be

directly used for safety analysis and for the global assessment of computer codes);

analytical tests designed to improve the basic knowledge of the fire and help in models

development and qualification.

The main objective of fire modelling is to provide well-qualified computer codes essential

for performing safety assessment. Actually for this purpose the FLAMME-S code is used.

For the future, the SYLVIA code will provide a set of models for simulating the fire

development (two zone and CFD approaches), the ventilation network components

behaviour and the aerosols (soot, radioactive materials) deposition and transfer between

the rooms and through the ventilation network. Furthermore, the SYLVIA code will be

coupled to the IRSN statistical tool, named SUNSET [5], thus allowing uncertainty

propagation and sensitivity studies on code input data and model parameters. The main

objectives of this new code development are to perform the coupling between all the main

phenomena involved during a fire in a nuclear plant (fire propagation, ventilation

behaviour, radioactive aerosols and soot transfers) and to provide different modelling

Texte relatifa la presentatio
levels for various users (a simplified approach for fast-running calculations used for

instance for PSA analyses; a detailed approach mainly for research activities).

Experimental programs in progress: IRSN is performing or is preparing 3 series of fire

tests:

* FLIP test: these tests are related to TPB/TPH fire interacting with a wall in an

confined and forced ventilated compartment,

* CARMELA test: these tests aim at providing knowledge of electrical cabinet fires.

In a first test, analytical approach is implemented in order to understand the

complex phenomena of electrical cabinet fires and notably the impact of some

parameters (ventilation effect, spatial arrangement, cabinet filling, effect of the

ignition location, quantity of combustible). In a second step, tests will be

performed in a real electrical cabinet in order to study the consequences of such a

fire notably on adjacent electrical cabinets and generation of inadvertent order,

* DIVA tests: this program firstly aims at studying all the consequences a fire,

located in a room, has on neighbouring rooms and on the ventilation network:

thermal propagation, smoke and fire spread, consequences of the fire on the

ventilation and room equipments, management of the ventilation during a fire. For

this program a new large-scale experimental facility has been built. It consists of

three rooms (L=6m, 1=5m, h=4m), a common corridor connecting these rooms, a

room located above the third room and the neighbouring area of the corridor. The

rooms are connected by a ventilation network and openings such as doors.

Fire scenarios selected: The fire scenarios that need research in order to improve the

fire risk assessment have been identified by IRSN personal that is involved in safety

assessment. These fire scenarios have been ranked to focus the fire research on

dominant needs. For NPP, the fire scenarios selected are:

* an electrical cable fire induced by a fixed or transient combustible fire,

* a fire on a process control relay rack in a relay room,

* an electrical cabinet fire,

* a fire propagation to a compartment located above,

Texte relatif A la prisentatio C-6
-3 -

* a fire in a containment (unconfined fire),

* a fire in a benchboard of the control room.

IRSN fire research needs: Basic research topics are clearly identified by IRSN in order

to improve the knowledge and modelling of the complex phenomena involved in fire

scenarios.

For the fire study, the topics are:

/ combustion parameters,

v' soot production,

/ improvement of the plume model in a confined and ventilated configuration,

/ explosion hazards due to the non-burnt residues,

/ fire propagation towards other fire sources,

/ criteria for the failure of equipment and the electric cables.

A complementary research program is conducted for the transfer of radioactive aerosols

inside a plant (including the ventilation network) and for the behaviour of the ventilation

and confinement devices submitted to the thermo-mechanical stresses induced by a fire.

The topics selected are, for example:

/ Plugging of the filters by the aerosols of combustion,

/ Setting up the suspension of radio-elements in the event of a fire,

/ Mechanical resistance of the filters,

/ Evolution of the aerosols of combustion outside the flame.

A first fire research program has been defined for the 3 first topics (combustion parameter,

soot production, improvement of the plume model). This program that foresees to begin

the research related to the combustion parameter in 2003 will be proposed in the frame of

the next budget.

Texts relatif a la presentatio C-7
FIRST APPLICATIONS OF A QUANTITATIVE FIRE HAZARD

ANALYSIS TOOL FOR INSPECTION IN THE

U.S. COMMERCIAL NUCLEAR POWER PLANTS*

* *Z * .@g+

Naeem qbal and Mark Henry Salley, P.E.

Office of Nuclear Reactor Regulation

Division of Systems Safety and Analysis

Plant Systems Branch

Fire Protection Engineering and Special Projects Section

ABSTRACT

Fires in a nuclear power plant (NPP) are a significant safety concern. The U.S. Nuclear Regulatory

Commission's (NRC's) new Reactor Oversight Process (ROP) uses a risk-informed approach to evaluate

the safety significance of inspection findings. As a part of this approach, the inspectors use a significance

determination process (SDP) to evaluate the significance of fire risks to the operating reactor, as required

by the new NRC inspection manual. A key step in the SDP is determining whether a credible fire scenario

is possible. The paper titled "Development of a Quantitative Fire Scenario Estimating Tool for the U.S.

Nuclear Regulatory Commission Fire Protection Inspection Program" -* introduced the new quantitative

analytical tools for performing fire hazard analyses (FHAs) being developed by the NRC Office of Nuclear

Reactor Regulation (NRR) fire protection engineering staff. These tools are designed for use by the regional

fire protection inspectors. The paper notes that a FHA is intended to permit fire protection inspectors to

quickly evaluate the potential for credible fire scenarios to cause critical damage to essential fire safeshutdown (FSSD) systems, components, or equipment. It also discusses the process of creating an

analytical quantitative tool based on the fire dynamics equations and pre-programmed correlations using

Microsoft Excels worksheets. These worksheets form the basis to be used to perform quick, easy, accurate

calculations. The first paper discussed how to estimate burning characteristics of fire (heat release rate,

flame height and burning duration), and hot gas layer temperature. Since then a second series of

computational worksheets with different concepts of fire dynamics have been developed and taught to the

regional inspectors. Applications which are discussed in this paper include: flame heat flux from a fire

source to a target fuel using a point source and solid flame radiation model, centerline temperature of a

buoyant fire plume, sprinkler actuation time and heat release rate (HRR) required to cause flashover in a

compartment. The NRR fire protection engineering staff is in the process of developing additional

worksheets to promote greater application of fire science engineering in the field during inspection.

Key words: fire hazards analysis, nuclear power plant, fire protection inspection finding, credible fire

scenario, fire dynamics, correlations, worksheet, quantitative methods

This paper was prepared by the NRC staff. The views presented do not represent an official staff position. The NRC has

neither approved nor disapproved h technical content.

This paper was presented at the Structural Mechanics in Reactor Technology (SMIRT) Post-Conference Fire Protection

Seminar No. 1, August 20-23,2001, at the Millstone Nuclear Power Station Conference Facility In WaWord, Connecticut

C-9
INTRODUCTION

One purpose of a fire hazard analysis (FHA) is to determine the effect of fires on the ability to operate the

facility safely, that Is, to protect the reactor and prevent the release of radiation to the environment. There

are a variety of methods of performing a FHA. In this second paper we describe more analytical methods

of quantitatively assessing fire hazards in NRC-licensed nuclear power plants (NPPs).

The NRC/NRR method uses simplified quantitative FHA calculation techniques to evaluate the potential for

credible exposure fire sources to cause critical damage to essential fire safe-shutdown (FSSD) systems,

components, or equipment, either directly or by igniting intervening combustibles, which in turn could cause

critical damage. The NRCINRR methods are based on material fire property data used in engineering and

scientific calculations. The fire hazard calculations used in these worksheets are simple empirical

correlations based on accepted fire dynamics principles.

REGULATORY BACKGROUND

The primary objective of the fire protection programs at U.S. NPPs is to minimize the probability and

consequences of fires. Fire protection programs for operating NPPs are designed to provide reasonable

assurance, through defense-in-depth (DID), that a fire will not prevent the performance of necessary safeshutdown functions and that radioactive releases to the environment will be minimized. Regulatory Guide

1.189, Fire Protection for Operating Nuclear Power Plants," April 2001, summarizes the multilevel approach

to fire safety. The fire protection DID program has three objectives:

1. To prevent fires from starting.

2. To detect rapidly, control, and extinguish promptly those fires that do occur.

3. To provide protection for structures, systems, and components important to safety so that

a fire that is not promptly extinguished by the fire suppression activities will not prevent the

safe shutdown of the plant.

The NRC's regulatory framework for nuclear plant fire protection programs (FPPs) is described in a number

of regulations and guidelines, including General Design Criterion 3 (GDC 3), 10 CFR 50.48, Appendix R to

10 CFR Part 50, Regulatory Guide 1.189, and other regulatory guides, generic communications (e.g.,

generic letters, bulletins, and information notices), NUREG reports, the Standard Review Plan (NUREG0800) (SRP), and branch technical positions (BTPs).

FIRE HAZARD ANALYSIS FOR NPPs

NPPs achieve the required degree of DID for fire protection using echelons of administrative controls, fire

protection systems and features, and safe-shutdown capabilities. A FHA should be performed to

demonstrate that the plant will maintain the ability to perform safe-shutdown functions and minimize

radioactive material releases to the environment in the event of a fire. Regulatory Guide 1.189 states that

the objectives of a FHA are to,

1. Consider potential in-situ and transient fire hazards.

2. Determine the consequences of fire in any location in the plant according to the ability to

safely shutdown the reactor and minimize and control the release of radioactivity to the

environment.

('-10
3. Specify measures for fire prevention, fire detection, fire suppression, fire containment, and

alternative shutdown capability for each fire area containing structure, systems, and

components important to safety in accordance with NRC guidelines and regulations.

NPP FIRE SCENARIO DEVELOPMENT

A fire scenario can be thought of as a chain of events that begins with the ignition of combustibles and ends

either with successful plant shutdown or core damage. A fire is postulated to occur at a specific location

in a specific fuel package and to progress through various stages of growth. As the fire grows, it may

damage plant equipment directly or indirectly (most often through electrical cables). For a given fire source,

the FHA may postulate damage to different equipment, depending on how long the fire burns and the initial

size of the fire. The postulated or predicted fire damage either directly or indirectly causes an initiating event

such as a plant trip, or loss-of-offsite power.

When developing a fire scenario, the inspector should conservatively postulate a significant fire provided

that the potential for a large fire is possible in the fire zone, area, or room. For example, in a large cabinet

fire the initial fire damage extends beyond the cabinet where the fire started. A large cabinet fire in its initial

stages may damage overhead cabling, an adjacent cabinet, or both. Assuming that electrical power is

interrupted the initial size of a pump or motor fire may largely depend upon the size of the oil spill. If the

configuration of the compartment, adjacent combustibles, etc., support the growth of a large fire, a large

fire should be postulated. Since large-fire scenarios are normally expected to dominate the risk significance

of an inspection finding, small-fires scenarios (for example a small electrical cabinet fire) are generally not

analyzed when large-fire scenarios can be postulated. Suppression is not credited unless suppression

could prevent the damage to the component. Automatic suppression, fire brigade, operator response, and

fire frequencies are accounted for in other parts of the SDP.

FIRE PROTECTION INSPECTION FINDINGS

A fire protection inspection finding usually concerns a failure or partial failure in meeting one of the

objectives of DID. If there are no DID-related findings against a fire protection feature or system, the fire

protection feature and system is considered capable of performing its intended function and remaining in

its normal (standby) operating state.

EFFECTS OF FIRE ON NPP OPERATIONS

Recent studies indicate that fires are a significant risk to the safe operation of an NPP (NUREG-1742). In

addition to local damage, heat transfer and the spread of smoke may cause damage far from the burning

object. A toxic mixture of combustion products in the smoke can hinder work in the area by reducing

visibility and creating a potentially lethal environment for plant personnel. Furthermore, the probability of

failures in electrical components increases as temperatures rise and smoke becomes more concentrated.

Empirical data indicates that a nuclear power facility experiences more event precursors (small fires that

have little impact on nuclear safety) than actual fire events such as the Browns Ferry Nuclear Power Plant

(BFN) Unit 1 fire (NRC Bulletin 75-04. March 1975). Many fire protection experts argue that no fire in an

NPP is without nuclear safety implications because every fire is a threat to safety through its effects on

equipment or operating personnel. Statistically however, a NPP is expected to experience a fire that affects

nuclear safety equipment every 6 to 10 years (Ramsey and Modarres 1998). The NUREG-1742 review of

individual plant examinations of external events (including some detailed fire probabilistic risk assessments

(PRAs)] showed that fire can be a significant contributor to a given plant's core damage frequency because

a single fire and its effects can result in the loss of an otherwise highly reliable redundant safety capability.

The loss of a redundant safety capability reduces possible success paths and may lead to core melt

damage accidents

C-1l
FIRE DEVELOPMENT

Fire hazards to NPP equipment may result from thermal destruction, fouling, corrosivity, and other sources.

Fire is essentially a rapid self-sustaining oxidation process, producing heat and light of varying intensities.

The chemical and physical reactions that take place during a fire are very complex and difficult to describe

completely.

A fire starts when in-situ or transient combustibles ignite and then release heat to the surroundings by

conduction, convection, andlor radiation. The rise in temperature in the fire compartment increases the

volume of gas and forces it out of the compartment. The flow of expanding gas out of the compartment

continues as the temperature rises. The pressure differential of the expanding gas across the compartment

boundary depends on a number of factors including (1) the leakage area (including the ventilation system

if applicable), (2) the volume of the fire compartment, (3) the rate of temperature rise, and (4) the rate of gas

generation from the combustion process. When the fire temperature reaches a steady-state value, the

gases in the fire compartment cease to expand. A balance is established as smoke moves out of the

compartment (primarily by buoyancy) and air moves in to replace the smoke.

DEVELOPMENT OF THE FIRE DYNAMICS WORKSHEETS

Our challenge was to develop a method that could be itaught to regional inspectors and put to use in a short

time. Regional inspectors have diverse backgrounds typically in electrical, mechanical, nuclear, chemical,

and civil engineering. We had to present the fire dynamics correlations so they could be understood by

engineers who had little or no formal education in the field of heat and mass transfer. We also had to

present the fire dynamics equations and correlations in a user-friendly format. After discussions with the

fire protection engineers from the U.S. Bureau of Alcohol, Tobacco and Firearms (ATF) we decided to

develop a series of Microsoft ExceP worksheets similar to ATFs' with the equations and correlations preprogrammed and locked in. The worksheets would allow quick, easy, accurate calculations. The

worksheets would also list the physical and thermal properties of materials commonly encountered in the

NPP. To begin the process, we had to select a series of fire dynamics correlation methods. We decided

to base our program on state-of-the-art methods from the SFPE Handbook of Fire Protection Engineering,

NFPA Fire Protection Handbook, and if necessary to modify the equations for use in specific NPP

application. The paper titled, Development of a Quantitative Fire Scenario Estimating Tool for the U.S.

Nuclear Regulatory Commission Fire Protection Inspection Program," presented at the Structural Mechanics

in Reactor Technology (SMiRT) Post-Conference Seminar No.1, 2001, discussed the first set of worksheets

that were put into use by the regional inspectors.

The following section describes the second addition of fire dynamics worksheets recently developed to

complement the first series.

METHODS OF PREDICTING HEAT FLUX FROM FIRE TO A TARGET FUEL

Introduction

The McCaffrey, Quintiere, and Harkleroad (MQH) and Foote, Pagni, and Alvares (FPA) temperature

correlations are not valid for analyzing a fire scenario in a large open compartment. Very large spaces such

as the reactor building in a boiling-water reactor (BWR) or the turbine building have too large of a volume

for a uniform hot gas layer to build up. In these scenarios, we must look at other forms of heat transfer such

as radiation. This section addresses radiation heat transfer when the target is at floor level.

Thermal radiation can be the significant mode of heat transfer for situations where a target is located

laterally from the exposure fire source. An example is a floor-based fire adjacent to an electrical cabinet

or a vertical cable tray in a large compartment.

C-12
Fire normally grows and spreads by direct burning, which results from impingement of the flame on

combustible materials or by heat transfer to other combustibles. The three modes of heat transfer are,

conduction, convection, and radiation. All these modes may be significant in heat transfer from fires. For

example, conduction is particularly important in allowing heat to pass through a metallic object in a solid

barrier and ignite material on the other side. Most of the focus on heat transfer in fires involves convection

and radiation. It is estimated that in most fires some 75% of the heat emanates by convection. The hot

products of combustion rising from a fire typically have a temperature in the range of 800 -1200 C (1472

-2192 F) and a density a quarter that of air. However, in an open industrial facility much of the convective

heat is dissipated into the atmosphere. Conversely, in a smaller building compartment the heat is contained

by the ceiling and walls. Radiation usually accounts for a smaller proportion of the heat generated from the

fire. Radiated heat is transferred directly to nearby objects. However, in large open spaces where a hot gas

layer is not established, radiation may be the most significant mode of heat transfer to evaluate. Thermal

radiation is electromagnetic radiation of wavelengths from 2 to 16 ptm (infrared). It is the net result of

radiation from substances such as H20, C02, and soot (often dominant in pool fires).

Critical Heat Flux to a Taraet

Radiation from a flame or any other hot gas, depends on the temperature and emissivity of the gas.

Emissivity is a measure of how well the hot gas emits thermal radiation. Emissivity is a value between 0

to 1, where 1 is a perfect radiator. The radiation that an observer feels depends on the emissivity and height

of the flame.

The incident heat flux required to raise the surface of a target to a critical temperature is termed the critical

heat flux. Measured critical heat flux levels for representative electrical cable samples typically range from

15 to 25 kW/m2 (1.32 to 2.2 Btu/ft2-sec). To account for inaccuracies, critical heat fluxes should be

established for screening purposes with values of 10 kW/m2 (0.88 Btu/ft2/sec) for IEEE-383 qualified cable

and 5 kW/m2 (0.44 Btu/ft2/sec) for non-IEEE-383 qualified cable. These values are consistent with selected

damage temperatures for both types of cables as referenced in EPRI's Fire-induced Vulnerability Evaluation

(FIVE) methodology.

Numerous methods have been developed to calculate the heat flux from a flame to a target located outside

the flame. Flames have been represented as cylinders, cones, planes and point sources to evaluate the

effective configuration factor or view factor between the flame and the target. The configuration or view

factor is a purely geometric quantity. It gives the fraction of the radiation leaving one surface that strikes

another surface directly. The predictive methods range from very simple to very complex methods. The

more complex methods involve correlations and detailed solutions to the equations of radiative heat transfer

and computational fluid mechanics. Routine FHAs are usually based on simple correlations because of the

macroscopic goals of the analyses and the limited resources available for routine evaluation. As a result

of the widespread use of these methods, a great deal of effort has gone into their development. Burning

rates, flame heights, and radiative heat fluxes can be predicted by these methods.

POINT SOURCE RADIATION MODEL

A point source estimate of radiant heat flux is the simplest and the most widely used flame representation.

To predict the thermal radiation field of a flame, the flame is modeled as a point source at the center of a

flame. More realistic radiator shapes entail very complex configuration factor equations. With the point

source model radiant heat flux varies as the inverse square of the distance to the target, R. With an actual

point or spherical source of thermal radiation, the distance R is simply the distance from the point, or from

the center of the sphere, to the target (Drysdale 1998 and SFPE Engineering Guide 1999).

The thermal radiation hazard of fires depends on the composition of the fuel, the size and the shape of the

fire, the duration of the fire, its proximity to the object at risk, and the thermal characteristics of the object

C-13
exposed to the fire. A point source exposure fire may start from either fixed or transient combustibles (e.g.,

electrical cabinet, pump, liquid spill, switchgear or motor control center (MC), or intervening combustible

some distance above the floor). For example, the top of a electrical cabinet is the point source we use for

a postulated switchgear fire. The point source of a transient combustible liquid spill or pump fire is located

on the floor.

The point source model assumes that radiant energy is released from the center of the fire. The radiant

heat flux is inversely related to the horizontal distance of the target from the fire. This is expressed

mathematically, in the following equation:

XrQ qw X.Q'_ = (1 )

where: = radiative heat flux (kW/m2 [Btu/seclft2)]

Q = heat release rate of the fire [kW (Btu/sec)]

R = radial distance from the center of the flame from edge of source fire [m (ft)]

y, = fraction of total energy radiated

In general, X, depends on the fuel, flame height, and configuration. It varies from approximately 0.15 for lowsooting fuels, such as most alcohols, to 0.60 for high-sooting fuels. In very large fires (several meters in

diameter), cold soot can envelop the luminous flames and reduce X, considerably. (See Figure 1.)

The heat release rate (HRR) of the fire can be determined by laboratory or field testing. In the absence of

experimental data, the maximum HRR for the fire, Q is calculated by the following equation (Babrauskas

1995):

Q = rAHc,1,ffAf (2)

where:

= heat release rate (kW)

m"= burning or mass loss rate per unit area per unit time (kg/m2-sec)

A, = horizontal burning area of the fuel ( 2)

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._1-

Figure 1 - Illustration of Radiant Heat Flux From a Point Source Fire to a Target Fuel

Appendix A gives an example of the use of a Microsoft Excel* worksheet to estimate flame heat flux to a

target fuel using point source radiation model.

SOLID-FLAME RADIATION MODEL WITH TARGET LOCATED ABOVE GROUND LEVEL

This worksheet provides a method for assessing the impact of radiation from pool fires to potential targets

using view or configuration factor algebra. The method included in this worksheet contains a range of

detailed calculations. Some methods are most appropriate for first order, initial hazard assessments, while

greater engineering effort is required for more detailed methods which are capable of better predictions.

The method presented in this section has been included in the Society of Fire Protection Engineering

(SFPE) Engineering Guide on Thermal Radiation. The accuracy of this method has been examined in the

SFPE Engineering Guide through comparisons of the method with available experimental data (SFPE

Engineering Guide 1999).

The solid-flame model assumes that the fire can be represented by a solid body of a simple geometrical

shape, with thermal radiation emitted from its surface, and that non-visible gases do not emit much

radiation. (See Figure 2.) The geometries of the fire, target, and their relative positions must be taken into

account since part of the fire may be obscured as viewed from the target thus changing the effective volume

of the fire. The thermal radiation intensity to an element outside the flame envelope is calculate by the

following equation:

4'=EF12 (3)

where:

= incident radiative heat flux (kW/m2)

E = average emissive power at flame surface (kW/m2)

F,,2= configuration or view factor

Emissive Power

Emissive power is the total radiative power leaving the surface of the fire per unit area per unit time.

Emissive power can be calculated by the use of Stefan's law, which gives the radiation of a black body in

relation to Its temperature. Because fire is not a perfect black body, the emissive power is a fraction (e) of

the black body radiation:

E = ea (4)

C-15
where:

E = flame emissive power (kW/m2)

T = temperature of the fire (K)

e = emissivity

a = Stefan-Boltzmann constant = 5.67 x 1 011 (kW/m2-K4)

Pad~ow~ FctwCN.

logu

Figure 2 - Solid Flame Radiation Model With No Wind and Target Above Ground Level

To use Stefan-Boltzmann's law to calculate radiation the inspector must estimate the fire's temperature and

emissivity. Turbulent mixing causes the fire temperature to vary. Therefore, it can be useful to calculate

radiation from data on the fraction of heat liberated as radiation, or to rely on measured radiation values.

Shokri and Beyler (1989) correlated experimental data on flame radiation to external targets in terms of the

"average emissive power" of the flame. The flame is assumed to be a cylindrical, black-body, homogeneous

radiator with an average emissive power. The effective power of the pool fire in terms of effective diameter

is given by the following correlation:

E = 58(10t°°-D) (5)

where:

E = flame emissive power (kW/m2)

D = diameter of pool fire (m)

* The effective power is the average emissive power over the whole flame and is significantly less than local

emissive power level. The emissive power decreases with increasing pool diameter because black smoke

outside the flame dims the radiation of the luminous flame.

For noncircular pools, the effective diameter is the diameter of a circular pool with an area equal to the

actual pool area. The effective diameter is obtained by the following equation:

D= 4 (6)

where:

Al = surface area of the noncircular pool

D = diameter of pool fire (m)

C'-16
Configuration Factor. View Factor or Shape Factor. F.,2

The configuration factor is a purely geometric quantity. It is the fraction of the radiation leaving one surface

that strikes another surface directly. In other words, it is the fraction of hemispherical surface area (or solid

angle) viewed by the differential element when looking at another differential element on the hemisphere.

The configuration factor is a function of target location, flame height, and fire diameter. Its value is between

0 and 1. When the target is very close to the flame, the configuration factor approaches 1 since the target

views only the flame. The flame is modeled as a cylinder with a diameter equal to the pool diameter, D, and

a height equal to the flame height, H,. If the pool has a length-to-width ratio near 1, a circular source of

equivalent area can be used to determine the flame height, H. for non-circular pools. (See Figure 3.)

The flame height of the pool fire is obtained by the following correlation (Heskestad 1995):

2

H, = 0235Q5 - 1.02D (7)

where:

H, flame height (m)

Q = heat release rate of the fire (kW)

D = diameter of the fire (m)

Figure 3 - Two-Cylinder Representation of the Configuration Factor for Target

Located Above Ground Level

As previously discussed, HRR of the fire can be determined by laboratory or field testing. In the absence

of experimental data, the maximum HRR for the fire, Q, is estimated by Equation 2. The radiation

exchange factor between a fire and an element outside the fire depends on the flame's shape, the distance

between the fire and the receiving element, and the orientation of the element to the fire. The turbulent

diffusion flame is approximated by a cylinder. Under wind-free conditions, the cylinder is vertical (Figure

2).

Given the diameter and height of the flame, Equations 9 is used to obtain the view or configuration factor,

F1.,2, for a cylindrical radiation source whose target is above the ground . Two cylinders are used to

represent the flame for a target above the floor. One cylinder represents the flame below the height of the

target, and the other represents the flame above the height of the target (Figure 3).

For targets above ground level, Equations 8 and 9 are used to estimate the two configuration factors for

Equation 9:

C-17
F S+1) (I) 

Fl. 2.V, = Ah, tan J(A + 1)(S -1) (8)

S2; (,1)(S + 1)

where:

h 2Hf,

D

2L

D

h,2+S2 +1

2S -

A}l2 _ han tan__(+ ]

A2 ,2 i (A2 +lXS-l) (9)

2rS4 An (A 2 -l~s+)

where:

h2 = 2Hf;

S = 2L

D 2

A- h2+S2+1

and:

L = distance between the center of the cylinder (flame) and the target

H. = height of the cylinder (flame)

D = diameter of cylinder (flame)

The total view or configuration factor at a point is the sum of two configuration factors:

F1.zv = Fj >2,v + 1-,2,V2 (10)

Appendix A provides an example of the use of a Microsoft ExceP worksheet to estimate flame heat flux to

a target fuel above ground level using solid flame radiation model with no wind.

A METHOD FOR ESTIMATING THE CENTERLINE TEMPERATURE OF A BUOYANT FIRE

PLUME

Introduction

A fire plume is a buoyant rising column of combustion products, not-yet-burned fuel vapor, and entrained

air. The plume of a fire in a building impinges on the ceiling unless the fire is very small or the ceiling very

high. A fire plume usually contains smoke particles. Surrounding air mixes into the plume and dilutes the

smoke which reduces the temperature. This mixing is called entrainment. To predict the course of a fire,

C-18
it is necessary to know the rate at which air is entrainmed into the plume. There are correlations for

calculating the rate of entrainment, but the results are not entirely reliable because small disturbances in

the air near the plume can have large effects on the entrainment rate. If combustion occurs only in the

lower part of the plume, there is approximately an order of magnitude more entrained air above the

combustion zone than the stoichiometric requirement.

A fire plume has two zones: the flaming (reacting) zone and the nonflaming (nonreacting) zone. The flaming

zone is just above the fire source; the fuel vapors released by the combustibles bum in this zone. The air

for the reaction Is entrained by the upward movement of the reactants. Above the flaming zone of the

column of hot combustion products is called the nonflaming zone since no reactions take place there.

Fire Plume Characteristics

Fire plumes are characterized in various ways depending on the scenario. The most common plume for

fire protection engineering applications is the point source thermal plume or buoyant axisymmetric plume,

which is caused by a diffusion flame just above the burning fuel. An axis of symmetry is assumed along the

vertical centerline of this plume. Another type of fire plume is the line plume. This is a diffusion flame

formed above a long narrow burner. Air is entrained from both sides of the burner as the hot gases rise.

Some examples of line fires are flames spreading over flammable wall linings, a balcony spill plume, a

burning long-sofa, a burning row of townhouses, and the advancing front of a forest fire.

Plume Temperature

The highest temperature Is at the plume centerline. The temperature decreases toward the edge of the

plume, where more ambient air is entrained, thus cooling the plume. The centerline temperature, Tp,.,*.),

varies with height. It is roughly constant in the continuous-flame region and represents the mean flame

temperature. The temperature decreases sharply above the flames as more ambient air is entrained into

the plume. The symbol &Tp,,..) represents the difference between the centerline plume temperature and

the ambient temperature, To. Thus ATp,,,-,)= Tp=,wb)- To.

There are numerous ways of correlating the height above the fire source and HRR to estimate the plume

centerline temperature. For example, consider a region of a ceiling jet at a radial distance from the fire axis

equal to the vertical distance from the fire source to the ceiling. In this region, the maximum velocity in the

jet drops to half the value near the fire axis, and the temperature (relative to the ambient temperature) drops

about 60 percent near the fire axis. The maximum velocity and temperature occur at a distance below the

ceiling equal to about 1 percent of the distance from the fire source to the ceiling. If the walls are very far

away, the temperature and velocity of the ceiling jet decay to negligibly low values before the jet reflects

when It reaches the wall. If the wall is close, the jet reaches the wall. The reflected jet goes back toward

the fire axis, just under the original jet. Thus the hot layer under the ceiling becomes thicker.

If the compartment has an open door or window and fire continues, the hot layer ultimately becomes thick

enough to reach the top of the opening, at which point the hot smoke-laden gases start to exit the

compartment. If the fire is next to a wall (or a corner), the behavior of the ceiling jet can be predicted

provided the fire is assumed to be twice (for wall) or four times (for corner) as large as the actual size.

Heskestad 1995, provided a simple correlation for estimating the maximum centerline temperature of a fire

plume as a function of ceiling height and HRR:

32

Tap,) - To = X(11)

(Z -Z0 )

C-19
where:

Tpt,,,,s,= plume centerline temperature (K)

To = ambient air temperature (K)

0. = convective HRR (kW)

g =acceleration of gravity (m/sec2)

cp = specific heat of air (kJ/Kg-K)

po = ambient air density (kg/m3)

z = distance from the top of the fuel package to the ceiling (m)

z = hypothetical virtual origin of the fire (m)

The virtual origin is the equivalent point source height of a finite area fire. The location of the virtual origin

is needed to calculate the thermal plume temperature for fires that originate in an area heat source. The

thermal plume calculations assume that the plume originates in a point heat source. Examples of area heat

sources are pool fires and burning three-dimensional objects such as electrical cabinets and cable trays.

A point heat source model is made for an area source by calculating the thermal plume parameters at the

virtual point source elevation rather than the actual arfa source elevation.

The virtual origin, 20, depends on the diameter of the fire source and the total energy released. The virtual

origin is given by:

2

D = -1.02 + 0.083 Q( (12)

D D

where:

z = virtual origin (m)

D = diameter of fuel source (m)

Q = total HRR (kW)

For noncircular pools, the effective diameter is the diameter of a circular pool with an area equal to the

actual area (Equation 5).

Total HRR,(O), is used when calculating the mean flame height and the position of the virtual origin. In

estimating other plume properties the convective HRR,(), is used since this is the part of the energy

release rate that causes buoyancy. The energy losses due to radiation from the flame are generally about

20% to 40% of the total HRR,(Q). Sootier and more luminous flames, often from fuels that bum

inefficiently, will have higher energy losses. The convective HRR is therefore often in the range Qc= 0.6

to 0.8 Q, where Q Is the total HRR and q, is the convective heat release from the fire.

Appendix A provides an example of the use of a Microsoft ExceP worksheet to estimate the centerline

temperature of a buoyant fire plume.

A METHOD FOR ESTIMATING SPRINKLER ACTUATION TIME

Introduction

It is often useful for an inspector to be able to determine if, or when automatic suppression will activate for

a postulated fire scenario.

Automatic sprinklers are thermosensitive devices designed to react at predetermined temperatures by

automatically releasing streams of water and distributing them in specified patterns and quantities over

C-20
designated areas. The automatic distribution of water is intended to extinguish a fire or control its spread.

A closed-element sprinkler is only activated when it absorbs a sufficient quantity of heat.

The effectiveness of a sprinkler installation depends upon the characteristics of the system itself (e.g., the

thermal rating and spacing of the sprinklers, how far the sprinklers are mounted below the ceiling, and their

pressure/flow characteristics), the characteristics of the building in which the system is installed (e.g., the

height of the ceiling, the volume of the compartment, the presence of openings, joists, or ventilation currents

at ceiling level), which can affect the flow of hot gases from a fire to the sprinklers, the type of combustibles.

and their closeness to the ceiling.

Sprinkler Activation

In a fire protection analysis, it is often important to estimate the burning characteristics of selected fuels and

their effects in enclosures including when fire protection devices such as automatic sprinklers, and thermal

and smoke detectors will activate for specific fire conditions. There are equations available based primarily

on experimental correlations, for estimating these effects.

Sprinklers are primarily activated by the convective heat transfer from the fire. Convection transfers heat

through a circulating medium, typically, air. The air heated by the fire rises in a plume, entraining additional

room air. When the plume strikes the ceiling, it spreads to produce a ceiling jet, in a shallow layer beneath

the ceiling surface, driven by the buoyancy of the hot combustion products. The thickness of the ceiling jet

flow is 5 to 12 percent of the height of the ceiling above the fire source, with the highest temperature and

velocity at 1 percent of the distance from the ceiling to the fire source. Heat-sensing elements of sprinklers

and thermal detectors are activated by the ceiling jet.

Computer programs have been developed to calculate the response time of sprinklers installed below the

ceilings of large compartments. These programs estimate the time to operation for a set-specified fire HRR

history. They are convenient because they avoid the tedious repetitive calculations needed to analyze a

growing fire. The same calculations can be easily done with a scientific hand calculator for stead-state fires

that have a constant HRR. If cases where a more detailed analysis of a fire that has important changes in

HRR over time is required, the fire may be represented as a series of steady-state fires one after another.

The following equation gives the time needed to heat the sensing element of a suppression device, from

room temperature to operation temperature, in a steady-state fire:

RTI ( T(), - T, (13

where:

tava~c, =sprinkler head activation time (sec)

RTI = Response Time Index (m-sec)' 2

us<,, = ceiling jet velocity (/sec)

Tie = ceiling jet temperature C)

To = ambient air temperature (C)

Tacvat activation temperature of sprinkler head (C)

RTI is the fundamental measure of the thermal sensitivity of sprinklers. The RTI is determined using plunge

tests in which the sprinkler is exposed to a uniform gas flow of constant temperature and velocity. The test

results can be used to predict the activation time of sprinklers in any fire environment. The RTI assumes

that conductive heat exchange between the sensing element and supports is negligible. The RTI is a

function of the time constant. , of the sprinkler head which is related to the mass and surface area of the

sensing element. Faster sprinklers have lower RTI and smaller time constants. Sprinklers with low time

C-21
constants typically have low ratios of mass to surface area. This is the basis of quick response sprinklers.

The RTI concept was developed by Factory Mutual Research Corporation (FMRC). It is given by the

following equation:

Rfl= hA 4 - (14)

where:

m = mass of element (kg)

cp(, = specific heat of element (kJ/kg-K)

h = convective heat transfer coefficient (kW/m2-K)

A. = surface area of element (m2)

u = velocity of gas moving past the sprinkler (m/sec)

The expressions for estimating the maximum ceiling jet temperature and velocity as a function of ceiling

height, radial position, and HRR were developed by analyzing of experimental data on large-scale fires

having HRRs between 668 kW to 98,000 kW. The expressions are given for two regions: where the plume

directly hits the ceiling and the surrounding region and, where the flow is horizontal.

The ceiling jet temperature and velocity correlations are given by the following equations (Alpert 1972, and

Budnick et al.,1997):

2

16.9Q 3 r

T - TO for H 018 (15)

H3 H

538(-) for --- >018 (16)

H

Uid =09 6(.Q r (17)

5' H for->.15 (18)

where:

T.,,, = ceiling jet temperature (C)

To = ambient air temperature (C)

Q = heat release rate of the fire (kW)

r = radial distance from the plume centerline to the sprinkler head (m)

H = distance from the top of the fuel package to the ceiling level (m)

upt = ceiling jet velocity (mn/sec)

These correlations are widely used to calculate the maximum temperature and velocity in the ceiling jet at

any distance, r, from the fire axis. Note, the regions where each expression is valid are given as a function

of the ratio of the radial distance, r, to the ceiling height, H. As the ratio of r to H increases with distance

from the centerline of the plume jet, r/H increases. For example, regions where rH>18, use Equation 16.

Equation 15 is used for a small radial distance where the hot gases have just begun to spread under the

ceiling.

(a-22
As with the temperatures there are two velocity regions in the ceiling jet flow, u: (1) one close to the

impingement point where velocities are nearly constant and (2) the other farther away where velocities vary

with radial position.

The ceiling jet temperature is important in fire safety analysis because sprinklers are usually on the ceiling.

Knowing the temperature and velocity of the ceiling jet as a function of radial distance enables inspectors

to estimate the response times of sprinklers.

The temperature and velocity of a ceiling jet also vary with the depth of the jet. Near the ceiling, the

temperature is at a maximum, then decreases downward. The temperature profile of a ceiling jet is not

symmetric like the temperature profile of a plume, where the maximum temperature is along the plume

centerline.

Knowing the ceiling jet temperature and velocity, the actuation time of a sprinkler can be estimated if the

spacing of the sprinkler and the RTI is known.

Appendix A provides an example of the use of a Microsoft Excel worksheet to estimate the sprinkler

actuation time.

A METHOD FOR PREDICTING COMPARTMENT FLASHOVER

Introduction

The likelihood of flashover can be estimated by determinating the temperature within a compartment during

a fire. Flashover occurs when the surface temperatures of combustibles rise, producing pyrolysis gases,

and the compartment heat flux ignites the gases. Flashover is assumed if the temperature of the smoke

layer exceeds 450 C (842 F). Flashover generally occurs when the smoke layer reaches temperatures

between 500 C (932 F) and 600 C (1 112 F). The hot-smoke layer is considered almost a black-body

radiator. At 450 C (842 F) the radiation from the smoke would be approximately 15 kW/m2 (1.32 Btu/ft 2-

sec). Fuel burning above 450 C (842 F) has a higher incident heat flux if the fire is in the open.

The International Standards Organization (ISO), defines flashover as "the rapid transition to a state of total

surface involvement in a fire of combustion material within an enclosure and the relatively abrupt change

from a localized fire to the complete involvement of all combustibles within a compartment" (Glossary of

Fire Terms and Definitions," ISO/CD 13943, International Standards Organization, Geneva, 1996).

NFPA 555 Guide on Methods for Evaluating Potential for Room Flashover," defines room flashover in terms

of temperature rise and heat flux at floor level. The NFPA guide gives a gas temperature rise at flashover

of 600 0C (1112 F) and a floor-level heat flux at flashover of 20 kW/m2.

Heat Release Required to Cause Flashover

The minimum HRR necessary to cause flashover in a compartment has been widely studied. The minimum

rate increases with the size of the compartment, and depends, on the ventilation in the compartment. If

there is too little ventilation, flashover cannot occur. If there is too much excess air flow, it dilutes and cools

the smoke, requiring a higher HRR to reach the critical temperature for flashover. The materials of

construction and the thickness of the ceiling and upper walls are also important factors in determining

whether flashover will occur and, if so, how soon.

There are several methods of estimating the onset of flashover in a compartment. The methods are usually

based on simplified mass and energy balances for single-compartment fires and correlations with

experimental data on fires.

C-23
Observations from full-scale fire tests and fire fighter experience describe flashover as a discrete event.

Numerous variables affect the transition of a compartment fire to flashover. Thermal influences are clearly

important when radiative and convective heat flux are assumed to be predominate. Ventilation,

compartment volume, and the chemistry of the hot-gas layer can also influence the occurrence of flashover.

Although the speed of the transition to flashover increases the uncertainties, the onset of flashover can still

be estimated by correlating with the considerable body of full-scale test data on flashover.

Thomas (1981), developed a semi-empirical correlation of the HRR necessary to cause flashover in a

compartment. He used a simple model of flashover in a compartment to study the effect of wall-lining

materials and thermal feed-back to the burning objects. He predicted a temperature rise of 520 C (968 F)

and a black-body radiation of 22 kW/m2 to a surface distant from burning wood fuel at the predicted critical

HRR necessary to cause flashover. According to the NFPA 555, room flashover potential is best estimated

by using Thomas's flashover correlation (Equation 18).

Thomas' flashover correlation simplifies the energy balance of a compartment fire. The correlation gives

the minimum HRR for flashover (Thomas 1981, Walton, and Thomas 1995, and NFPA 555 2000 Edition):

QFO = 78AT + 378A47 (19)

where:

Qua = heat release rate to cause flashovber (kW)

AT = total area of the enclosing compartment surfaces (M2), excluding the area of the vent

opening(s)

A = area of the ventilation opening(s) (M2)

H = height of the ventilation opening(s) (m)

The constants in Equation 18 represent values correlated to experiments producing flashover.

This equation requires that the duration of the fire be known or that the fire has been burning for a long

period of time and the heat conduction has become steady-state.

Typically a few minutes up to around 30 minutes is a reasonable range of time for estimating the likelihood

of flashover. Firefighter response time is also usually within this range (Karlsson and Quintiere 2000).

Appendix A provides an example of the use of a Microsoft Excel worksheet to estimate the HRR necessary

to cause flashover.

SUMMARY

The additional fire scenario estimating tools described In this paper will advance the NRC risk-informed

inspection process in several ways:

1. The use of simple fire dynamics correlations will enable regional fire protection inspectors to

transition from purely qualitative fire risk evaluations to evaluations based on both qualitative and

quantitative methods. The correlations will decrease the reliance on opinion and reduce the

uncertainties in fire risk evaluations.

2. The worksheets with locked-in equations and correlations will allow regional inspectors to more

easily perform fire hazard analyses, reduce the potential for mathematical errors and the

misapplication of the SFPE Handbook of Fire Protection Enaineerina and NFPA Fire Protection

Handbook equations.

C-24
3. Regional inspectors gain insights into the fire risk scenarios by having tools that can rapidly be

changed to calculate potential fire dynamics effects.

LESSONS LEARNED AND IMPROVEMENTS

Lessons learned and improvements have come about primarily during training of the inspectors in the

quarterly NRC regional fire protection inspectors workshops and the inspector's applications of the

worksheets In actual NPP inspections. There are three major areas where lessons learned/improvements

have been made to date.

I1. One advantage of worksheets is the tabular listing of material fire property data. Collecting the input

to the fire dynamics equations and correlations for this is a project in itself. There were three

lessons learned identified. First, when there are several values in the literature for the same

material, which value should be used? This was a problem with HRRs for cable jackets. The

solution was to pick the "best" value and use only that value in the worksheet. If the licensee has

a more precise value the inspector can input that value. The second problem is unavailable or

incomplete data. This problem was discussed in training workshop sessions. Much of the HRR

data currently available was funded and developed for a specific end-user. For example, the

General Services Administration (GSA) (which deal mostly with office environments) HRR values

may not be applicable to NPPs. At times inspectors have to correlate the scenario they are

developing with known data that may not, at first, seem applicable to NPPs. Third, some of the

existing data does not fully describe the potential hazard. A good example of this is the HRR for

electrical cabinets. The published data focus on combustibles in the cabinet (typically cable

insulation) and neglect possible large energy release [amperes squared multiplied by time (12t)].

The fire at San Onofre Nuclear Generating Station, Unit 3, on February 3, 2001, showed that heat

from an electrical fault in a cabinet can vaporize copper conductors and destroy surrounding metal

cabinets. For medium- and high-voltage applications, preliminary NRC research indicates that

these HRR values may be under predicting by a factor of 1000. Inspectors are aware of this and

are instructed to use higher values to include the electrical energy when they can justify the higher

values. Additionally, the inspector are trained in the fundamentals of fire dynamics and the use of

the engineering correlations to recognize those configurations where the correlations are

appropriate and where they should not be used. The NRC/NRR staff fire protection engineers are

always available for inspector consultation to ensure the proper application of these analysis tools.

2. Most of the equations and correlations in the worksheets are simple mathematical expressions.

The mathematical expressions are not limited and sometimes give physically impossible values.

To prevent such errors, the worksheets have red warning flags added. If a value exceeds known

limits, a red flag appears. For example a red flag appears when an equation increases room

temperature values well beyond those physically possible.

3. For convenience the new worksheets use pull-down menus and dialog boxes. This enhancement

will allow the users to select the single input, instead of entering all the parameters associated with

the input. For example, an inspector can simply click on "concrete" in the menu and the correct

parameters appear in the equation. This enhancement will also eliminate manual errors in entering

the table values in the equations.

C-25
CONCLUSION

Using commercial available spreadsheet software (like Microsoft Excen) to create a series of computational

worksheets, the techniques of fire dynamics analysis can be taught to and reliably applied by inspectors.

The worksheets also reduce mathematical complexities and errors.

The NRR fire protection staff is continuing to develop additional worksheets for regional inspector

application In the area of fire risk evaluation. The worksheets discussed in this paper are the second set

completed and put into use. The NRC/NRR fire protection engineering staff expects to complete the full

suite of fire dynamics worksheets in about 3 years.

ACKNOWLEDGMENTS

The authors would like to thank Gary Holahan, Director, Division of Systems Safety and Analysis, NRC/NRR,

John Hannon, Chief, Plant Systems Branch, NRC/NRR and Eric Weiss, Chief, Fire Protection Engineering

and Special Projects Section, Plant Systems Branch, NRC1NRR for the opportunity to develop this project.

The authors also thank the NRC regional managers and fire protection inspectors for their contributions.

C-26
REFERENCES

Alpert, R. L., "Calculation of Response Time of Ceiling-mounted Fire Detectors," Fire Technology, Volume

8, 1972, pp. 181-195.

Babrauskas, V., "Burning Rates," Section 3, Chapter 3-1, SFPE Handbook of Fire Protection Engineering,

2nd edition, DiNenno, P. J., editor-in-chief, National Fire Protection Association, Quincy, Massachusetts,

1995.

Budnick, E. K., Evans, D. D., and Nelson, H. E., Simplified Fire Growth Calculations" Section 11, Chapter

10, NFPA Fire Protection Handbook. 18 edition, Cote, A. E., editor-in-chief, National Fire Protection

Association, Quincy, Massachusetts, 1997.

Drysdale, D. D., Chapter 4, "Diffusion Flames and Fire Plumes," An Introduction to Fire Dynamics 2d

edition, John Wiley and Sons, New York, 1998, pp.109-158.

Foote, K. L., Pagni, P. J., and Alvares, N. J., Temperatures Correlations for Forced-Ventilated

Compartment Fires," Fire Safety Science-Proceedings of the First International Symposium, International

Association of Fire Safety Science (IAFSS), pp. 139-148, Grant and Pagni, editors, Gaithersburg Maryland,

Hemisphere Publishing Corporation, New York, 1985.

Heskestad, G., Fire Plumes," Section 2, Chapter 2, The SFPE Handbook of Fire Protection Engineering,

2nd edition, DiNenno, P. J.,editor-in-chief, National Fire Protection Association, Quincy, Massachusetts,

1995.

lqbal, N., and Salley, M. H., "Development of a Quantitative Fire Scenario Estimating Tool for the U.S.

Nuclear Regulatory Commission Fire Protection Inspection Program," Structural Mechanics in Reactor

Technology (SMIRT) Post-Conference Fire Protection Seminar No. 1 August 20-23, 2001, at the Millstone

Nuclear Power Station Conference Facility in Waterford, Connecticut.

ISO/CD 13943, "Glossary of Fire Terms and Definitions," International Standards Organization, Geneva,

1996.

Karlsson, B., and Quintiere, J. G., Chapter 6, "Gas Temperature in Ventilated Enclosure Fires," Enclosure

Fire Dynamics, CRC Press, New York, 2000, pp. 115-140.

McCaffrey, B. J., Quintiere, J. G., and Harkleroad, M. F., "Estimating Room Temperature and Likelihood

of Flashover Using Fire Test Data Correlation," Fire Technology, Volume 17, No. 2, pp. 98-119, 1981,

NFPA 555, "Guide on Methods for Evaluating Potential for Room Flashover," National Fire Protection

Association, Quincy, Massachusetts, 2000 edition.

NRC Regulatory Guide 1.189, "Fire Protection for Operating Nuclear Power Plants," April 2000.

NRC Bulletin 75-04, "Cable Fire at Browns Ferry Nuclear Power Station," March 24, 1975.

NUREG-1742, Volume 1, "Perspectives Gained From Individual Plant Examination of External Events

(IPEEE) Program," draft report for public comments, U.S. Nuclear Regulatory Commission, Washington,

DC, April 2001.

Ramsey, C. B., and Modarres, M., Commercial Nuclear Power Assurance Safety for the Future, John Wiley

& Sons, Inc., New York, 1998.

C-27
Shokri, M., and Beyler, C. L., Radiation from Large Pool Fires," SFPE Journal of Fire Protection

Engineering, Volume 1, No. 4, pp.141-150, 1989.

SFPE Engineering Guide, Assessing Flame Radiation to External Targets from Pool Fires," Society of Fire

Protection Engineers, Bethesda, Maryland, June 1999).

Thomas, P.H., Testing Products and Materials for their Contribution to Flashover in Rooms," Fire and

Materials, Volume 5, Number 3, September 1981, pp. 130-111.

Walton, W. D., and Thomas, P. H., 'Estimating Temperatures in Compartment Fires," Section 3, Chapter

3-6, SFPE Handbook of Fire Protection Engineering, 2nd edition, DiNenno, P. J., editor-in-chief, National

Fire Protection Association, Quincy, Massachusetts, 1995.

C-28
APPENDIX A

SAMPLE PROBLEM

This is an example of how to do an engineering FHA using the NRC/NRR fire dynamics Microsoft Excer

worksheets.

STATEMENT OF PROBLEM

During a routine fire protection inspection, a NRC inspector discovers a significant oil leak in a station air

compressor. It is important to determine whether a fire involving 20 gallon spill of lubricating oil from a

compressor could damage the safety-related cable tray and electrical cabinet in an access corridor in the

fuel building. The compressor is on a pedestal approximately 1.0 foot above floor level and has a 12 f2

(1.12 M2) oil retention dike. The safety-related cable trays are located 8 ft (2.45 m) above the corridor floor

with a horizontal distance of 4 ft (1.2 m) from edge of the compressor's dike. The horizontal distance

between the compressor dike and the electrical cabinet is 5 ft (1.52 m).

The access corridor has a floor area of 20 x 15 ft (6 x 4.6 m), a ceiling height of 10 ft (3 m), and has a single

unprotected vent opening (door) of 4 x 6 ft (1.22 x 1.4 m). The compartment has no forced ventilation. The

compartment construction is 1 ft thick concrete. The corridor has a detection system and a wet pipe

sprinkler system. The nearest sprinkler is rated at 165 F (74 OC) with a RTI of 235 (m-sec)"2) and located

9.8 ft (2.98 m) from the center of the dike. Determine if there is a credible fire hazard to the safety-related

cable trays and electrical cabinet.

Use the following worksheets to evaluate fire scenario.

1. Heat flux to the target (electrical cabinet) using point source model, q:_

2 Heat flux to the target (cable trays) using the solid-flame radiation model, ,

3. Centerline plume temperature, Tp( 0,,,a)

4. Sprinkler activation time, t

5. HRR necessary to cause flashover, QFO

ANALYSIS

Accidental spills of flammable and combustible liquid fuels and resulting fires depend on the composition

of the fuel, the size and shape of the fire, the duration of the fire, its proximity to the object at risk, and the

thermal characteristics of the object exposed to the fire. Liquids with relatively high flash points (like lube

oil or diesel fuel) require localized heating to ignite. However, once started, a pool fire spreads rapidly over

the surface of the liquid spill. To perform a conservative FHA, it will be assumed that the 20 gallons of

lubricating oil will be spilled into the diked area and the over heated compressor ignites the oil.

The summary results of the calculations are given in table. See Microsoft Excel* worksheets for details of

the calculations.

C-29
Fire Hazard Calculation for Compressor Lubricating Oil Spill in Access Corridor

Heat flux to target Heat flux to target Centerline plume Sprinkler activation HRR necessary to

(electrical cabinet) (cable trays) temperature time cause flashover

,,, 40 Traceso %W10

(kW/m2) (kW/m) [ OC (F)] (min)Q0

I__ _ _ _ _ _ _ _ _ _ _ _ _I__ _ _ _ _ _ _ _ _ _ _ _ _ I__ (kW )

12.50 17 689 (1272) 2 2100

It should be noted that exposure to high plume temperatures could potentially cause the unprotected safetyrelated cable trays to fail. The flame heat fluxes to the electrical cabinet and the cable trays are high

enough to damage them.

The results of the calculation demonstrate that a pool fire with a 12 ft2 dike area in an access corridor could

damage unprotected safety-related cable trays and electrical cabinets. The analysis also suggests that for

the postulated oil fire, the sprinkler system, if operabhq, should activate and should provide some protection

to the safety-related cables and equipment.

C-30
METHOD OF ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET

LIQUID FUEL AT GROUND LEVEL UNDER WIND-FREE CONDITION

POINT SOURCE RADIATION MODEL

INPUT PARAMETERS

Mass Burning Rate of Fuel (m')

Net Heat of Combustion of Fuel (AHw)

Fuel Spill Area or Dike Area (As*)

Distance between Pool Fire and Target (L)

Radiative Fraction (x)

THERMAL PROPERTIES FOR

BURNING RATE DATA FOR LIQUI

Where q' = Incident radiative heat flux on the target (kW/M2)

Q = pool fire heat release rate (kW)

X, = radiative fraction

R 2 distance from center of the pool fire to edge of the target (m)

C,-31
Pool Fire Diameter Calculation

Ad~* = xD2/4

D=

D=

(4 Ag1)2

1.19 m

Heat Releae Rate Calculation

a = m"AH¢Ad

Where 0 = pool fire heat release rats (kW)

W = mass burning rate of ful per unit surface area (kg/m2-sec)

eHc= net heat of combustion of fuel (kJ/kg)

Adm= surface area of pool fire (area Involved n vaporization) (m2)

Q = 2000.02 kW

Dltance from Center of the Pool Fire to Edge of te Target Calculation

R = L+Dt2

Where R= distance from center of the pool fire to edge of the target (m)

L = distance between pool fire and target (m)

D = pool fire diameter (m)

R= 2.12 m

Radiative Het Flux Calculation

q-= Q74 OxR

*12.40 kIWhm . .09 TUW-ec ANSWER

FAILURE CRITICAL HEAT FLUX FOR CAI3LES

Cable Type Damage Threshold Damage Thieshold

Heat Flux (IW/m)

IEEE-3 qualified 10

IEEE-383 unquaified 5

Reeroe Flre-IrApoed \hdeabilty Evaluation (FIVE), page 6-14

C-32
METHOD OF ESTIMATING RADIANT HEAT FLUX FROM FIRE TO A TARGET

LIQUID FUEL ABOVE GROUND LEVEL UNDER WIND-FREE CONDITION

SOLID FLAME RADIATION MODEL

Mass Burning Rate of Fuel (m)

Net Heat of Combustion of Fuel (AHEA)

Fuel Spill Area or Dike Area (Adm)

Distance between Pool Fire and Target (L)

Vertical Distance of Target from Ground (Hi = -

THERMAL PROPERTIES FOR

ESTIMATING RADIATIVE HEAT FLUX TO A TARGET FUEL

~skmm. D~rR~P~g~qs~47')

SOUD FLAME RADIATION MODEL

q'= EF12

Where q' = Incident radiative heat flux on the target (kW/m2)

E = emissive power of the pool fire flame (kWm2)

F12 = view factor between target and the flame

Pool Fire Diameter Calculinion

Am = RD9/4

D= (4 0AId2

D= 1.19

Eisnlsive Power Calculation

E = Ss (

1 0 oooaaD)

E = S6.71

m

(IcWfm~

C-33
View Factor Calculation

Fjv = /(KS)tan-'(h,(S-1 )"2HhS)tan-'((S-ly(S+I))"2 +AhES(A,2 -1)"2

tan-'((A,+1 )(S-y(A-1 )(S+1))2

F1zv2 = 1I(xS)tan-'h 2(SP-1 )

1

'Hh 2 S)tan ((S-i y(S+ 1))" 2

+A2h CxS(A2

2 1-)1

2tan'((A2 )(Sry(A,1 )($1 ))t2

A, = (h,1 +S2+1)12S

A2 = (h2

2+S2+1)/2S

B = (I +S2 2S

S = 210D

h, = 2H,,D

h2 = 2H,JD

F1zv= Fjzv, + Flzv2

Where F,2V = total vertical view factor

R distance from center of the pool fire to edge of the target (m)

Ht= height of the pool fire flame (m)

D= pool fire diameter (m)

Distance from Center of the Pool Fire to Edge of the Target Calculation

R = L+D12 = 1.815 m

Heat Relase Rate Calculation

= m-H 0A.

a . 2000.02 kW

Pool Fire Flame Height Calculation

H= 0235 Q02-1.02 D

H.= 3.699 m

S =2R/D= 3.047

h= 2H,,ID = 3582

N = 2HuD = 2(H1-Hn)/D = 2 8

A, = (h,2+S2+1,)2S = 3.793

A,= (h2+S2+1)2S = 2.821

B = (1+S2 )t2S= 1.687

F1ZH= 0.153 0.093 0.231 0,388 0.750 o.13 F1zv1

F1ZV = 0.143 0.077 0.170 0294 0.800 0.143 Fiav2

Fzv = 0296

Raditive Heat Flux Calculation

q = EF12

16.70a Wn' 1.4 DlUfee ANSWER

FAILURE CRITICAL HEAT FLUX FOR CABLES

Cable Type Damage Threshold Damage Threshold

Heat Flux (kW/M 2)

IEEE-S3quallfled 11.4

IEEE-383 unqualified 5.7

Reience Fire-Indiced Vunembilty Evalon (FIVE), page 0-14

C-34
METHOD OF ESTIMATING TEMPERATURE OF A BUOYANT

FIRE PLUME

P~ a should Bh _d ONLY 11 TH YUOWl PUT PAMEI mOXp *.

1 s _ - -- _ e

INPUT PARAMETERS

Net Re. Rate of Mi. Fire JO)

Dlstarc from Ii. Top of to Fuel to te Celing (z) ks o Cambuwtib Fuel ( li 12 ft, ' sX

AMBIENT CONDITIONS

AmlenfArTerprature (To) 77.00 F 4 1

Specific Heat of Air (ev) 1 00 K

Amblent Air Derly (P) 1204m

Acceleration of Grity () 9.81 iVsee

Convective Heat Releae Fracton 050

ESTIMATING PLUME CENTERUNE TEMPERATURE

T._,. T. * 91 fug ci 2 P Q" 4 (z -z'

Wher 0. Corecti porlion of to hea re rate (W)

To ambent adr temperate (K)

g - accelon of Wm*v mii)

c spec hea ofdar Vl.l

PO amblent alr drul 0kghn

z . dm from Ie bp of the UW padag to the °te (im)

zo. hypodheca viruhl orin of tire (im)

Canveemth Heet Rel"e Ret. Calculation

0.- 2.Q

Where 0 - heat releae rae of ti firs (M

Z. - onvecive heat releas frecion

4. loo kW

Pool Fire Dlsm*e Csouhalon

D . (4 '

D* 1I m

Hypoltcel Virual Orgn Caleubon

z.10 - 1.02 + 0.oo3 (Q)/D

Whr z. * cdghn o oflthe fre (m)

O . heal r ab s of s lW)

o . demelr of pool ire (m)

zoll* 0.44

Z0- 0.52 m

Ceuaerflne Plum Temperatie. Calcuation

T-Me) 9.1 i P N4( ZZOZ* 1 0

T.*) -To - 8e422

T_ - . 962.22 K

Yiseeq S ^ . , ~ l , A.. .S:WE... ..

C-35
METHOD OF ESTIMATING SPRINKLER RESPONSE TIME

Parameta should be Mfed ONLY U T7HE YELLOW WPMT PARAMETER BOXES.

INPUT PARAMETERS

Heat Release Rate of the Fire (Q) 2 0 w

Sprinkler Response Time Index (RTI) 235 (reec)"2

Activation Temperature of the Sprinkler Head ( 165 VF)

Distance from the Top of the Fuel Package to the Ceiling Level (H) M-0t '*-YSm

Radial Distance from the Plume Centerline to nearest Sprinkler Head (r) 9.80 t) fl.

Ambient Air Temperature (To) 68.00 (F) ,.t; ;

Convective Heat Release Fraction k) 0.70

r/H= 1.09

GENERIC SPRINKLER RESPONSE TIME INDEX (RTL FOR Standad response bulb

- * NE P#1I

*Note: The actual RTI should be used when the value Is muaIhlall

GENERIC SPRINKLER TEMPERATURE RATING (Tuf".,)- FOR I Ordinary

*Nobe: The actual trnorature ratina should be used =Ie the valueIs available.

ESTIMATING SPRINICLER RESPONSE TIME

taw-o (RTI)u ,,2 In (Tj, -To)/Ti, T2aw)

Where to- = sprinkler activation response time (sac)

RTI = sprinkler Response Tirne Index (m-sec)

uw = ceiling et velocfly (m/sec)

T. = ceiling jet temperature (IC)

To = ambient air temrperature ( eC)

TWhere = activation temperature of sprinler head (C)

C-36
Coing Jet T _nipture Calation

T1 -T. 1. 9 (Q 4" or H * 0.18

TI -T. 5.3 (QJW2M for > ,18

Whom Tit caing Jet OMPture (C)

To * ambient air temprature (C)

l.* oonvective podfon of the heat rlase rabl ()

H * istare from the top of t lunl padca to t coling level (n)

r - dat dsanoo rom Om plume cenbilne to the sprntler hoad ()

Convewc HWt R _ase Rae Colcul0n

0.- 2Q

Whe Q ht release rate o ()

X. ccnvrcvo heat release fraction

0. 1400 kW

Radd Den to Ceil Heht Rallo Ca ton

dH. 1.06 rIH > 0.1B

Tp, -To * 5.38 (QCO"/H

TO -To - 118.34

T. 138.34 (-C)

Cang t Vabft CalcAtion

4m *S Q (QiH) br rM - 0.15

., - (0.1 0 Q H')r for r > .15

,. clig fat Velocity (ec)

W*hat rms t of n fWe NW)

H - cldano from the top of to fuel pacae to the cellng lVel (n)

= mst diance from th plume cenlte o tw pdnler head (m)

Radil Detanoe to Coing Heiht RAio Calcuation

dH 1.09 r/H > 0.15

L4. - (0.195 Q Hyr

Lu- 1.36 mec

SpeiniaeAstfation Time C ealldon

t_. . (RTt)hA'* In Ts -T.)Yi -T..

l.. s,.ea 111.60

7kaapaddaruU rp 1111iVIII l lJim nimdwlth ANSWER

NOTE: I tpMm . NUM' Sprlnkdr Is not actvat

C-37
METHOD OF PREDICTING VENTED COMPARTMENT FLASHOVER

INPUT PARAMETERS

COMPARTMENT INFORMATION

Compartnt Width (w.) | 2*,

Compant Length (I.) | jetw 4 32

Compartnent Height (h,) | M.

Vent Width tW4) r 4.00t , - w*

Vent Height (H,) F &oo - m 

METHOD OF THOMAS

QFo . 7.8 AT + 378 H )"

Where OFo = host release rate of the fire (kW)

AT - otal area of the compartrent enosicng surface boundarlee (m)

A - area of ventilation opening (in2)

K * height of ventilation opening (m)

Ar of Venafiofn Opnng Calmitlon

A. W.)(H.)

A. 2.2 m

2

Are of Comparmnt Encebing Surface Boundaries

AT * (WcXW + 2(hxw.) + 2(h.4c)] -A

AT- 11&54 i

2

Mirdmu Rat of Hea Relern for Flashover

QO - 7.8 AT + 378 A (HA )

.o4A 314.4 kW ANSWER

C-38
SESHP/GMEIPS/FLSIC4

O/NT/02.337

INSTITUT DE RADIOPROTECTION ET DE SURETE NUCLEAIRE

DEPARTEMENT DE RECHERCHES EN SECURITE

, .; I , 1,

;<7

, , r

I , N / 'N \ J >

;q 3 I '

j•L ~~ '.

L- -

14 -

REDACTION VERIFICATION QUALITE APPROBATION

NOM E. Bouton C. Casselman P. SOUSSAN R. Gonzalez,

DATE V'/2&t ),1o6ioT | t4/06/02 |4ZS/o6I

VISA

REV. A

REV. B

Titre Overview of the FLAMMES code validation matrix

Auteur(s) E. Bouton

Type: NT Numero:

SESHP/GME/IPS/FLS/C40/NT/02.337

Service d'Essais de Sret6 Hors Pile

Groupe Mod6lisation et Etudes des Feux

La diffusion des informations contenues dans ce document aupres d'un tiers exterieur a l'IRSN est

soumise a 1'accord de 1'unit6 emettrice de 1'RSN.

This document, which contains proprietary or other confidential or privileged information, and any reproduction in whole or in part,

shall not be dissininated outside the organization of the recipient without prior approval of the IRSN.

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Page 2/19

IRSN/DRS/SESHP/GMEF Cadarache, le 25/06/2002

SESHP/GME/IPS/FLS/C40/NT/02.337

Overview of the FLAMMES code validation matrix

E. Bouton

La diffusion des informations contenues dans ce document aupres d'un tiers exterieur a 1'IRSN est

soumise a I'accord de I'unit 6mettrice de 1'IRSN.

This document, which contains proprietary or other confidential or privileged information, and any reproduction in whole or in part,

shall not be dissiminated outside the organization of the recipient without prior approval of the IRSN.

C-40
IRSN/DRS/SESHP/GMEF Overview of the FLAMMES code validation matrix

SESHP/GME/IPS/FLS/C4

O/NT/02.337

Page 3 /19

SERVICE D'ESSAIS DE SURETE HORS PILE

Groupe Mod6lisation et Etudes des Feux

Nat. Document NT

TITRE Overview of the FLAMMES code validation matrix

Auteur(s) E. Bouton

Type de diffusion: "Mots c16sm: Nbre de pages: 199

Normale Nbre de figures: 3

RESUME:

Ce document presente une vue d'ensemble de la matrice de qualification du code

FLAMMES.

ABSTRACT:

This document is an overview of the validation matrix of the FLAMMES code.

Rep~re bureautfique: SESHP/GMEtIPS1FLS/C40/NT/02.337

BP 3 - B4ilment 346 -13115 SAINT PAUL LEZ DURANCE

Y :04 42 25 31 77 - Fax :04 42 25 48 74

Sibge social: 77-83, avenue du G6neral de Gaulle - 92140 CLAMARTStandard: (33) 01 46 54 88 88 - RCS Nanterre B 440 546 018

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O/NT/02.337

1 INTRODUCTION

This note has been written in the framework of the International Collaborative Project

to Evaluate Fire Models for Nuclear Power Plant Applications organized by the NRC. Its aim

is to give to the participants or the FLAMMES users an overview of the validation matrix of

the code. Therefore, in this document, only the FLAMME-S major features anfithe test

conditions are described. More detailed information can be found in the references, mostly

written in French and not open to release.

2 OERvIEW OF THE FLAMME_S CODE

The FLAMMES code was developed to compute the consequences of a fire in

nuclear power plants or in industrial facilities. This code is based upon a classical two zones

model and it can be applied to a single or a multi-room configuration. The main

characteristics of the FLAMN4E_S code are:

* The flame and the plume above the fire pool are described with the

empirical correlations set by Heskestad. The Mac Caffrey's plume model is

currently under development.

* The calculation of the radiative exchanges inside the room (on walls and on

targets) due to the flame relies on a classical point source approach.

* The heat loss of the gases through the walls by conduction is taken into

account and can induce the heating of the gases of a target room near the

fire room.

* The rooms of the facility can be connected with a ventilation system (at a

constant or variable flow rate) or with vertical vents like doors.

* No ceiling jet or horizontal vent models are available.

FLAMMES can be used autonomously or coupled with the SIMEVENT code

devoted to the calculation of flow rates in complex ventilation networks. But the description

of this ventilation code is beyond the scope of this paper.

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O/NT/02.337

3 VALIDATION DOMAIN

The objective of the validation process of the FLAMMES code is to evaluate the

calculation results for several different configurations, in terms of:

* the room's number of the facility (up to 3 rooms),

* the location of the pooFfire (in the middle of the room or against a wall),

* the ventilation conditions (forced or natural),

* the kind of fuels used.

All the tests series considered in the validation matrix are listed in the following table:

Cnfiguratonn; 00--Loationofth -sTt pool ire e series Number f tests

Single room In the middle of the room LIC, LPI, PEPSI 13

Single room Against a wall FLIP 5

Multi rooms In the middle of the room Cooper 19

Multi rooms Against a wall Peacock 7

Table 1 List of the test series considered in the validation matrix

Additional information about the test conditions is indicated below or may be found in

the references. Furthermore a "rough" criteria, the relative error, has been used to evaluate the

quality of the agreement between calculations and test results. When the relative error is less

than 20 %, FLAMME_S can be used with confidence for similar calculation conditions. All

the tests listed in this document satisfy this condition, except some Peacock's test (See §

3.3.2).

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3.1 Fuel used during the test

The different kind of fuel used during the tests are indicated in the following table.

TPH LIC2.CB

70% TPH - 30% TBP 70% (C12H26) - 30% LIC/FLIP

(C12H27 04 P)

Ethanol C2H60 1 LICI.14/FLIP

Mineral Oil C31,34H63,9 LPI

(DTE medium) _ _

Domestic fuel C15,55H29,3 LPI13

Methane CH4 Cooper

Methane/acetylene Peacock

Table 2 : List of fuels

TPH: Hydrogened Tetra Propylen

TBP: Tri Butyl Phosphat

More detailed characteristics of the fuel are given in annexe.

3.2 Single room tests performed at IRSN

3.2.1 Centred fire pool

The different tests achieved with the fire pool in the middle of the room [5], [6] are

indicated in the table below.

Area of the pool Fuel Facility Ventilation Test

(M2 ) (Volume m3

) conditions

(LxlxH) ou (SxH)

(wall material)

0,0314 Mineral oil 4,35 m3 confined LPI 7

(DTE medium) (0,856 mx5,35 m) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ( t e e l w a l )_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

0,0314 Mineral oil

(DTE medium)

4,5 m3

(2,011 m2 x2,24 m)

(steel wall)

confined LPI 9bis

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0,0629 Mineral oil 4,5 m3 confined LPI 10

(DT'E medium) (2,011 m2X2,24 in) _____________ medium)___ _ (steel wall)

1 70% TPH - 30% 400 m' mechanical LIC 2.3

TBP (9 mx6 mX7,6 m) (3 V/H)

(concrete wall)

1 70% TPH - 30% 2000 rn3 Natural LIC 2.8.1

TBP (10 mxlO mx20 m)

(concrete wall)

1 70% TPH - 30% 3600 mft confined LIC 2.CA

TBP (20 mxl5 mxl2 m)

(concrete wall)

1 TPH 3600 m' confined LIC 2.CB

(20 mxl5 mxl2 in)

______________ _ (concrete wall)

1 Mineral oil 400 in3 mechanical LPI lA

(DTE medium) (9 mx6 nX7,6 m) (5 V/) LPI 11

(concrete wall) PEPSI I

1 ethanol 400 mn mechanical LIC 1.14

(9 mx6 mx7,6 m) (5 V/H)

(concrete wall)

2 Mineral oil 400 m3 mechanical LPI 12

(DTE medium) (9 mx6 mx7,6 m) (5 V/H) (concrete wall)

5 70% TPH - 30% 2000 n' Natural LIC 2.8.5

TBP (10 mxlO mx20 in)

(concrete wall)

5 Mineral oil 2000 3 Natural LPI 13

(DTE medium) (10 mxlO mx20 m) (concrete wall)

5 Domestic fuel 2000 in3 Natural LPI 19

(10 mxlO mx20 in)

(concrete wall)

Table 3: List of IRSN tests (centred fire)

3.2.2 Fire pool against a wall

In the FLIP tests [1], [8], the fire pool was located against the south wall of the

PLUTON facility (V = 400 in3, lxwxh 9 mx6 mx7,6 in). In this facility, all the walls are made

of concrete except the south wall which was covered with a thermal insulating material made

of thermipan. Whatever the test considered, the steady ventilation flow rate before the onset

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of the fire was 3 volume changes per hour. The squared inlet (0.5 x 0.6 m2) is located in the

bottom and in the middle of the north wall ; the squared outlet (0.5 x 0.8 m2) is in the top and

in the middle of the west wall (cf. Figure 1).

Inlet

Outlet

Fire Dool

U

Figure 1: overview of the PLUTON facility

Additional information about the FLIP test is listed below:

Area of the pool Kind of fuel Q (kW) Test

(m2)__ _ _ _

A:0.4. TBPITPH 360( i

0.4 Ethanol 215 FLIPIA

1.0 ~ !:~TBP/TPH- :645. L;.

1.0 Ethanol 510 FLIP2A

-f: 1.5- ;}f0 . 0 0BPITPH T i i: ; ; of 1 pi- of - LIP7

Table 4: List of IRSN FLIP test (fire pool against a wall)

Remark: Q is the average heat release rate (W)

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3.3 Multi-room tests

The FLAMvES code was validated in multi-room configurations by using the tests

performed by Cooper [4], [91, [10] and Peacock [7], [2], [3].

3.3.1 Cooper tests

The facility used by Cooper has 2 or 3 rooms, with a variable length for the corridor.

The surface of the total floor is in the range of 40.6 In2 to 89.6 m2 .

a~~~~~~~~~~~~~~~~~m~~~~~~~

. .. . I f: _ ~~~~~~~~~~~I'.

V a£ 

Camuu IUl jM -' FUNCl;Z4 I ml

Figure 2: Overview of the Cooper facility

A square gas burner (0.3 x 0.3 m2) is set in the middle of a room and is supplied with

methane. In the tests, the fire duration does not exceed 10 mn. The steady heat release rate of

the fire (Q) is 25, 100 or 250 kW. The growth of the fire is modeled as:

Q(t) = 30 t with 0 < t < 10 mn (Q in kW)

The other test conditions are listed in the following table:

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. ~ ~ ~ i . or C or'-o t: : k.m or; Q (kW) 1⁄2 corridor codor or Ccoridor Corridor Corridor Coridor CorridOr

and lo:bby 11 oo 14dor 1door

25 x x x x

100 x x x x x x x

225 x x x x

Ramp x x x x

fire

Table 5: List oZ Cooper tests

3.3.2 Peacock tests

An overview of the facility used by Peacock is displayed on the following scheme. It

is composed of two or three rooms connected by doors.

Door 2

Hood I Door Door 3

Room 3

Corridor

Door 1

Room 1

*'- - Gas burner

Figure 3: Overview of the Peacock facility

The burn room walls are made of ceramic fiber and those of the second and third room

are covered by gypsum board. Furthermore, the room dimensions are indicated in the

following table:

-fRoom L (n) x width(in) x height(i)-

Voum e (i )

1 2.34 x 2.34 x 2.16 (11.83 m3)

2 12.19 x 2.44 x 2.44 (72.6 m3)

3 2.22 x 2.24 x 2.43 (12.1 m

3 )

Table 6 Room dimensions of Peacock's facility

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A gas burner is set against a wall of the first room. The fuel is a gas mixture made of

methane and acetylene. The heat release rate of the fire (HRR) is varied in the range of 100 to

500 kW. The combustion products are collected by a hood located just behind the second

door. By using the 2 consumption method, the HRR of the fire is deduced from hood

measurements and not directly recorded with a weight device. This is the main difference

with the other tests performed and listed in the validation matrix.

The conditions of the Peacock's tests are summed up in the table below:

Test number Q (kW) Dor Thir roomi 

(crior)J

1 100 Open No

L; : i4 0 ; 4000 100 ::5 Open ; Yes.

5 300 Open No

6 0 :; 0300 -; 0 iClosed Yes

7 300 Open Yes

8E 500 Open V No

9 500 Open Yes

Table 7: List of Peacock's tests

Concerning these tests, some restrictions about the agreement between calculations

and test results must be made. Whatever the test considered, the average room temperature is

well estimated ; the maximum value reached in the fire room in the case of the 500 kW heat

released rate is very high around 550 C. The flow rates through the door connecting the fire

room to the corridor is also in good agreement with measurements. This is not true for the

other doors of the facility probably due to the uncertainty on measurements. Furthermore, the

upper layer temperature is enough over-estimated and the lower layer temperature underestimated; for these variables the relative error is beyond 20 % criteria.

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4 CONCLUSION

Some general remarks can be drawn from the validation process about the limitations

and the validation domain of the code. The upper layer temperature (resp. the lower layer

temperature) is generally over-estimated (resp. under-estimated) even if the agreement

between calculations and measurements is good. Given a facility and a forced ventilation flow

rate before-the-start-of the fire, the accuracy of the calculation decreases as a function of the

heat release rate of the fire. These results are in agreement with the literature and not limited

to the FLAMMIE_S code. They are likely link to the two zone approach.

Given the previous limitations, the FLAMME_S code is well validated over a large

range of test conditions derived from the literature or from experiments performed at IRSN

(more details of the tests used are given below). The main results of the comparison between

the calculations and the experiments are the following:

1/ The relative error is less than 20 percents for the main thermodynamical

parameters like the pressure in the room, the oxygen concentration and

temperature in each layer, the average temperature of the wall and the

ventilation flow rate, except in some Peacock tests (See § 3.3.2).

2/ The FLAMMES code is validated for single room configurations (18 IRSN

tests) and for multi-room configuration (19 tests performed by Cooper and 7

experiments achieved by Peacock).

Therefore the FLAMME_S code can be used with confidence in the following

conditions:

* The room walls are made of concrete or of steel.

* The height of the room is equal or greater than the smallest horizontal

dimension of the room.

* The room is sealed or connected to the outside with vertical openings or

with a ventilation network (the flow rate is in the range of 3 to 5 volume

changes per hour before the start of the fire).

* The fire pool is set in the middle of the room or against a wall.

* The fuel is a gas or made of mineral oil or of an organic liquid.

* The ratio of the pool area to the area of the floor of the facility is less than 5

percents.

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* The pyrolysis rate of the fuel is an input data.

* The ratio of the heat release rate to the volume of the facility is less than

5kW/m3 .

In the next future, new validation exercises are planned. FLAMMES will be used tosimulate the resultsobtained ina multi-room configurations with naturaLand mechanical

ventilation (DIVA tests).

5 REERENCES

[1] Bouton E., (1999), "Qualification du code FLAMMES (v2.3) dans le cadre de la 1

serie d'essais de feux de liquides en interaction avec une paroi",

SESHP/GME/IPSIFLS/C40/RA-99.1332.

[21 Bouton E., (2000), "Qualification du code FLAMME_S en configuration multilocal

Essais Peacock: Etude preliminaire", IRSN/DRS/SESHP/GME[IPSIFLSIC50/RP01.797.

[3] Bouton E., (2001), "Essai Peacock et Al (1988) - Etude de qualification du code

FLAMME_S (Contrat EURIWARE n 4020 2 B043220 - lot 2)",

SESHP/GME/IPS/IFLS/C50/RP-01.836.

[4] Cooper L. Y., Harkleroad M., Quintiere J., Rinkinen W., (1982), "An experimental

study of upper hot layer stratification in full-scale multi-room fire scenarios", Journal of

Heat Tranfer, Vol. 104, pp 741-749, 1982.

[5] Malamas M., (2000), "Logiciel FLAMMES Version 2.3 Notice de qualification",

SESHP/GME/IPS/FLS/C40/RA/00. 115, Contrat n°4020 28COR01 80.

[6] Malamas M., (2000), "Logiciel FLAMMES Version 2.3 Rapport de qualification",

FLAMME_S_99/NT/006, Contrat n°4020 28COR0180.

[7] Peacock R. D., Standford D., Billy T. L. (1988), " An Experimental Data Set for the

Accuracy Assessment of Room Fire models", National Bureau of Standards,

Gaitherburg, MD 20899, NBSIR 88-3752.

[8] Pernot B., (2000), "Qualification du code FLAMMES / SIMEVENT partir des

essais FLIP", GME/IPS/FLS/lRP/0l.036l.

[9] Tourniaire B., (1998), "Etude bibliographique d'essais de feux grande chelle en

configuration multilocal", SESHP/GMEF/n°EF.30.40.R/98.414.

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O/NT/02.337

[10] Tourniaire B., (1998), "Qualification du code FLAMME_S v2.3 en configuration

multilocal: 1 partie - Essais de Copper, Harkleroad, Quintiere et Rinkinen",

SESHP/GMEF/n0 EF.30.40.R198. 1234.

Remark:

Reports written in French are the IRSN's property and not open to release.

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ANNEXEl : CHARACTERISTICS OF THE FUELS

Legend:

M: molar mass

- - PCI: standard heat of combustion-(MJ/kg)

X,: heat fraction released by the flame as radiation

p: density

Kind of fuel M lm)-. Va. P.C MJ;k) p (- T;st 

Ethanol 46 25.6 0.25 794 FLIP

46 26.78 0.25 794 LIC1. 14

TBP/TPH 195.25 36 0.35 836 FLIP

195.25 40 0.35 816.8 LIC2.3

LIC2CA

195.25 32 0.35 816.8 LIC2.8.1

LIC2.8.5

Mineral Oil 439.98 41.86 0.35 870 LPI

PEPSI

Domestic fuel 215.9 40 0.35 840 LPI19

TPH 170 40 0.35 749 LIC2CB

Methane 16 55 0.24 Cooper

Methane/actetylene 20.96 46.54 0.25 Peacock

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ANNEXE 2: CHEMICAL REACTIONS

In the validation process, the combustion products are composed by 120, 05P2 C2, C

and the chemical reaction is written in the following way:

--CaHbOcPd +8 [02 +3.7742N 2}- >b/210+d/205 P 2 + aC02 + PC

It is possible to compute the mole number of each product with the following

assumptions:

* Every hydrogen atom is combined with oxygen to product water,

* Phosphor atoms in the fuel form 05P2,

* The mass fraction of soot to mass of burnt fuel is p.

Given these assumptions, the different mole numbers are written as:

a =a- (pI10)MfejMso = (/l00)Muej 1/M.,0, 8 =0.5 [b/2+ (5/2)d+ 2 a - c]

TBP/TPH

Test i 02 O2 C %)

LIC23 18.298 11.929 0.071 10*

LIC2.8.1 16.02 9.651 2.349 24*

LIC2.c.a 16.107 9.738 2.262 13.9

LIC2.8.5 16.042 9.673 2.327 14.3

FLIP 16.091 9.722 2.278 14

*,B= (p/l00) Mfi /M~so - (l)MOSP21Msoo

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Mineral oil

''T- est';'-'5:'; %<; CO2 C - p(%)-tf-$f-- 

LPI7 43.905 27.93 3.41 9.3

LPI9bis 43.282 27.307 4.033 11

LPI10 44.125 28.15 3.19 8.7

- LPI11A

LP111

LPI12 45.738 29.763 1.577 4.3

L P I13 _ _ _ _ _ _ _ _ _ _ _ _ _6

PEPSI 44.525 28.55 2.79 7.62

Other fuels

Fuel V0CO2 C p - )

Domestic fuel 20.356 13.031 2.519 14

TPH 17.083 10.583 1.417 10

Methane 2 1 0 0

Methane/acetylene 2.428 1.329 0.046 2.63

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International Collaborative Project to Evaluate Fire Models for

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ZONE MODEL VALIDATION OF ROOM FIRE SCENARIOS

0. Keski-Rahkonen and S. Hostikka

VTT Building and Transport, P.O. Box 1803, FIN-02044 VTI, Finland

Tel. +358 9 456 4810, Fax +358 9 456 4815, e-mail: Olavi.Keski-Rahkonen@vtt.fi

ABSTRACT

Part of tre results of the Scenario B of the CIB W14 Round Robin for

computer fire code assessment are presented. The scenario consisted of

three subscenarios. Each of them was a single room with natural

ventilation and a wood material fire source. Sixteen participants from

ten countries using eleven different computer codes demonstrated the

calculation of scenario B. The participants used two CFD-codes and

nine two-zone models from 1997 to 1998. In this short report

calculation results using codes developed at NIST are compared with

measurements and discussed in general.

INTRODUCTION

Zone and field models describing fire development and smoke movement are

commonly used as a part of advanced design or fire safety evaluation of buildings.

Although numerous efforts to compare fire models with experiments have been

published, systematic validation of the plethora of existing fire codes is lacking. This

deficiency has become critical due to the introduction of performance based building

codes, which often encourage the use of numerical simulations. Designers and

authorities, which may not be knowledgeable about fire simulation, should be given

guidance on which codes to use and on the limits of the models. VTT organized a

round robin of fire simulation within the auspices of CIB W14. Two rounds of

calculations were arranged. In the first, scenario A, users, programs, and their

technology were studied simultaneously. The main result was, that the user is the

most critical component. No further details are given here on scenario A. In scenario

B the major objective was to test te performance of the technology although also it

revealed a lot from the user contribution. This presentation summarizes the most

important findings from that round concentrating on technology contained in CFAST

and FIRST model codes originating from NIST.

OVERVIEW OF SCENARIO B

Scenario B consisted of three subscenarios B, B2 and B3. The experiments

corresponding to the subscenarios were conducted during the years 1983, 1985 and

1986 in the VTT testing hall, shown in Figure 1, jointly by VTT and Technische

Universitfit Braunschweig (Hagen & Haksever 1985). Originally, the aim of the test

series was to study full compartment fires. Subscenarios B 1 and B2 shown in Figures

2 and 3, consisted of a single room with a door/window open to ambient. The names

of the tests during the test programme and the room sizes are shown in Table 1.

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Table I - The subscenarios. Test times were actually longer than the times mentioned

here, but the given times were chosen for the Round Robin.

Test label Room size

(M3)

Fire load

(kg)

Fire load density

(MJ/m 2 )

Peak RHR

(MW)

Test time

(min)

Bl SF83-3 15 x 7.2 x 3.5 1989 330 1 100

B2 SF85-10 20 x 7.2 x 3.6 1815 220 14 180

B3 SF86-10 7.4 x 7.2 x 3.6 2 x 500 330 5.2 120

0 5m lOm

Figure 1. Schematic longitudinal cut of the testing hall. Dimensions are in mm.

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Plan view

I. I

240l

. ... -. I -

1

AAn- I 44U

Side view

Figure 2. Subscenario BJ.

Plan view Side view

Figure 3. Subscenario B2.

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EXPERIMENTAL DATA REDUCTION FOR FIRE MODEL VALIDATION

Here only data reduction of calculation of interface height and layer temperatures is

treated. The height of the smoke layer interface is one of the key variables studied

during the fire safety analysis of the buildings. It is a natural output variable for two

zone model fire codes where the assumed existence of the interface is part of the

model. However, when the question is about experimental or CFD data, where

temperature is measured/calculated in discrete number of points, there is no general

consensus about the correct calculation method for the interface height.

Kawagoe (1958) presented a one-zone model for a post flashover fire with

ventilation to ambient and discovered that the flow rate was proportional to the vent

factor AJH. The two-layer concept was introduced by Thomas et al. (1963) who

presented the relationships of the layer heights, temperatures and the flow rates.

Prahl and Emmons (1975) and Rockett (1976) further studied the hydrodynamic vent

flows and presented the relationships between the interface and neutral plane heights

and the mass flows in/out of the vent. A careful presentation of the flow equations in

the vent has been given by Tanaka (1978), later included in zone model code BRI2

(Tanaka & Nakamura 1989). More recent reviews about the subject have been given

by Thomas (1992) and Cox (1995).

In principle, when the fire is sufficiently small compared to the size of the

compartment two layers will form. The height of the layer interface can be found by

determing the inflection point of the vertical temperature profile. However, in the

case of a relatively strong fire, as is the situation in the present scenarios, a single

layer may form, with very small vertical temperature gradients. This is demonstrated

in Figure 4 showing the development of the vertical temperature profiles inside the

compartment in B3. Each line represents one time point. The absolute level of the

temperature has been removed for linear presentation by transformation using:

T(zi, t) = T(Zmin t) + tI (1)

where T is in 0C and t in minutes. It can be seen that the development of the hot layer

is clear up to the 20 minutes or flashover, after which the difference between the

uppermost and lowest measurement is small and no large gradient exists, not to

mention a true discontinuity assumed in the papers of Thomas et al. (1963) and

Rockett (1976).

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One of the most common methods to determine the interface height is to use the socalled N percent rule, suggested by Cooper et al. (1982). The interface height at time

t is defined to be the elevation z; at which the temperature first satisfies

3

2

I 1.5

0.5

D 20 40 B0 00 100 120 140

Time (min)

Figure 4. Mean temperature profiles during the experiment B3.

T(zj,,t) -T, N (2)

T(z, P, 0 t) - Tanb 100

In the literature the values suggested for N range from 10 to 20. The method was

applied to the current scenarios with a value of N = 15. The average temperatures in

the upper and lower layers were then calculated as mean values of the measurements

in the upper and lower sides of zi, respectively. In cases where z = 0 the lower

layer temperatures are meaningless.

Mathematically the question is: "How to calculate three unknown variables, zi, Tu

and TL, from the series of temperature measurements at discrete number of heights?"

Quintiere et al. (1984) introduced a method to calculate the upper layer temperature

Tu as an arithmetic average of the upper thermocouple readings. One then solves zi

and TL from integral equations

H (3) J T(z)dz = (H - zi)Tu + ziTL 

0

=(H - z)--+ z.-.4

0T(z) TU TL

where H is the ceiling height. Equation (3) describes the mathematical averaging

procedure of the zone model, but has no physical meaning, although it is quite close

to the requirement for enthalpy equivalency. Equation (4) is a requirement for mass

equivalency.

The goal of this experimental data reduction is to produce data that can be directly

compared with the zone model results. The applied calculation method should

therefore be able to give interface height and average temperatures that produce the

same hydraulic flows as the zone models. Janssens and Tran (1992) introduced a

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International Collaborative Project to Evaluate Fire Models for

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method that combined the mass flow equations of Prahl and Emmons (1975) and

Rockett (1976) with the mass integral (4). The problem of this method was that at

high temperatures, the mass flow out of the vent is very insensitive to small changes

of temperature and the mathematical solution of the system became difficult. They

also presented an alternative method where the interface height was taken from the

inflection point of the temperature profile. As their example cases had clear layer

structures they had good results but here this method can not be applied.

For the round robin comparison the following procedure was used:

1. The lower layer temperature TL is taken to be the average of the thermocouple

readings of the lowest measurement points.

2. The interface height and upper layer temperature were solved from the integral

equations (3) and (4). Combining these equations gave expression for the

interface height

3.

TL 2 - H2 ()I 

II+ 2TL2-2TLH (5)

where

H H

II= JT(z)dz and 12 =TZ ) (6)

0 0~~~ T(z)

The problem of this method is the calculation of integrals (6) using relatively few

measurement points. Interface heights calculated by this method will be presented

together with those calculated with the N-percent rule with N =15.

Shortly after these analyses were made He at al. (1998) treated the problem in a

through way. They also concluded the N-percent rule results deviated from the two,

methods to define the layer height: integral ratio method (given by equations (3) and

(4)) and a more refined least squares method. The algorithm of CFAST produced

data close to integral ratio and least squares methods.

PARTICIPANTS

CFAST

The model code CFAST comes from the package HAZARD I, developed at NIST

(Peacock et al. 1997). CFAST was used by Jason D. Averill from NIST, Petra

BUttner from Hosser, Hass & Partner (HHP) and Daniel Joyeux from Centre

Technique Industriel de la Construction Metallique (CTI).

Version: 2.21 (HHP and CTI) and 3.1 (NIST)

Physical models:

* Multi-room two layer model

* McCaffrey entrainment law

* Pyrolysis / Heat release rate given by user

* Maintained carbon-hydrogen-oxygen balance

* Ceiling-floor and inter compartment heat transfer

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FIRST

The model code FIRST (FIRe Simulation Technique) was developed at the National

Bureau of Standards (NBS), (Mitler & Rockett 1987). During the round robin it was

used by Daniel Joyeux from CTI.

Version: September 1987

Physical models:

* One compartment two zone model

Several plume models: Morton-Taylor-Turner (virtual and fire base source points),

McCaffrey, Zukoski, Delichatsios and Kawagoe

RESULTS

For shortness in this paper only subscenario B 1 is presented. Results are similar from

other scenarios described in the full paper (Hostikka & Keski-Rahkonen 2002).

Comparisons of the measured and calculated interface heights are shown in Figure 5.

Calculation results for two different methods are presented: the 15 %-rule in

Equation (3) and the density integral method in Equation (5). The quality of the

agreement between the measurements and the calculations depends on the method

used. As mentioned before, in this subscenario, the existence of an interface is

questionable due to the very small vertical temperature gradients. The following

observations can be made:

There is a lot of deviation between both the different CFAST curves and between the

CFAST simulations and the measurements. Only NIST and HHP's open round

simulations are close to each other during the first 60 minutes.

CFAST show very high interface heights where the height of the base of the flame

was assumed by the modellers to be 1.4 m.

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International Collaborative Project to Evaluate Fire Models for

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3. - - - - - - v , vI Measured (15%) 1

3 l Measured ' ~ - - -(p) - 2 B1^ 

3 - CTI-CFA ------ - - -

i - - HHP-CFA-B

2.5 - - HHP-CFA-0O ..... NIS-CFA

~- - - - - - - -

a1.5 -- C.,.,,, , 

0 .5 - - - - - - - - - - - - --

20 40---- 60 a --------1 0

Time (min)

FigureS. Comparison of interface heights given by CAST zone model and

measurements in subscenario BJ. The major change in the HHP-simulations was the

different base of the flame height.

CFAST

CTI

The comparison between calculations with CFAST and experimental results

indicates in a first approach rather bad calculations results. This is the results of the

fact that a lower (cold) zone has to exist during calculations while the experimental

data do not imply that. The calculation results of the upper layer temperature are

always higher than the measured, with 300 or 400 C. According to author, this result

is a good result because such codes have to be used for fire safety calculations, their

results have to be in a safe side. According to the author a more convenient

comparison could be made by calculating a mean temperature of the whole

compartment, ie. by using a one zone model. However, a two zone model as CFAST

can also be used and can give good temperature results as an envelop of the

experimental results.

HHP

There is a great deviation between experimental and measured data especially

concerning the interface height and the species concentrations. While the

experiments show a room which remains nearly completely filled with the smoke

layer, the code calculates an increasing interface height after the burning peaks. In

B 1 the interface height calculation results were enhanced when the height of the

flame basis was decreased. The deviation may also be caused by the 15%-rule used

for the experimental determination of the interface height.

The maximum temperatures of the upper layer show a good agreement with the

measured values. In this field the code shows a sufficient accuracy. The calculated

upper layer temperatures are somewhat higher than the measured ones but this is

consistent to the fact, that, according to the calculations, a part of the room (the lower

layer) has only temperatures between 200 and 400 'C.

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The measured 02 concentration is well approximated by the calculation, whereas

there are some differences concerning the concentrations of CO and C02. Especially

the CO production is strongly depending of the course of the fire and difficult to

predict.

FIRST

Simulation of the scenario B was not possible with the Delitchatsios and Kawagoe

air entrainment models. The run with Zukoski model did not converge. The MortonTaylor models and the McCaffrey models gave results and converged all along the

simulations. The results obtained with the three models were rather similar. The

reported results were given using the McCaffrey model.

The comparison between calculations with FIRST (Figure 6) and experimental

results indicated very bad results as the scenarios were not very good applications for

a two zone model. In terms of interface height, as the two zone model needs a lower

zone, the lower zone had to exits in all three subscenarios. The upper layer

temperatures were always lower than the experimental ones. A difference of about

200'C between measured and calculated temperature was generally obtained in the

upper layer temperature comparison.

The oxygen concentration calculations are rather closed to experiments but the

carbon dioxide calculations under-estimate the experimental results. This happened

partially because the calculation results were given in mass fractions but the

experimental data in mole (volume) fractions.

3. v

I v Measured (15%) Bi

3 - ------- i Measured (p) - -

3P-- _- CTI-FST

g2.5 . IPS-FLS -----

x *ee I - , I ~~~~~~~~...........................

CD

vi , I I

Z 2 --- --

.Time (min)

Figure 6. Comparison of interface heights given by FIRST and FLAMME-S zone

models and measurements in subscenario B].

Comparison of the measured and calculated upper layer temperatures are shown in

Figures 7 and 8. The limits of the temperature averaging are based on the interface

heights calculated by the 15%-rule. However, the method used for the interface

calculation had very little effect on the averaged temperatures. Effects of the

radiation on the operation of thermocouples were not considered. Below are listed

the visual observations concerning the comparison.

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International Collaborative Project to Evaluate Fire Models for

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CFAST calculations by HHP show a very good agreement with the measured

temperature during the first 50 minutes. CTI and NIST in turn achieved considerable

over- and underestimations of the maximum temperatures, respectively.

FIRST show good agreement during the first 25 minutes. After that FIRST starts to

underpredict.

1400

1200 ---- -- 4- 

800 -~~~ -

i 1, 1 --------- ------ 1 000 -? 

A)800 _.-i _ - - -2a __.__

1 600 -- - - . ----------------

Measured

400 - CTI-CFA

--- HHP-CFA-B

200 -... HHP-CFA-C

. NIS-CFA

o 20 40 60 80 100

Time (min)

Figure 7. Comparison of upper layer temperatures given by CFAST zone model and

measurements in subscenario B.

1800

i1600 -i B1

1 60 0 - - - - - - - - L- - - - - - - - - - - - - - - -: - - - - --

1400 ---- -- - __ I I------ I

1200 -------- - Measured

6'1000- - , --- --- IPS-FLS

I 

n E ' | hi_ " |~~~~...... IP -C IS

A' 800 _ _ sZ_ 

400 -, - --- --

200 - o - - -- -- - - - -- - - --------- __-- - --- ___ t ___ 

0 20 40 60 80 100

Time (min)

Figure 8. Comparison of upper layer temperatures given by FIRST, FLAMMES and

CISNV zone models and measurements in subscenario BJ.

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GODNESS DETERMINATION OF THE RESULTS

Based on the previous sections one can say, that each of the codes reproduces the

qualitative behaviour of the layer height and upper layer gas temperature. It is not

easy to see from the tens of plots, which of the codes performed better than the other

ones. A summary of the calculation results of the two-zone models is here given to

facilitate making conclusions. The purpose of the summary is not to judge or rank the

codes, but to estimate the state of the art of the technology. Since the user seems to

be the biggest source of error, it is reasonable to try to decouple the effects due to the

user and due to the code itself. Therefore, only the simulation, that seemed to have

the best overall agreement with the measurements, was selected for the summary.

Here no distinction was made between the blind and open calculations. The summary

cannot be complete, because some of the codes were used by only one participant. In

these cases the comments of the participants should be taken into account to decide

whether the simulation is representative or not.

Goodness of fit by formal methods like least squares analysis of multivariable

functional relationships or any alternative test is not yet worthwhile. Pearson has

shown (Cramer 1946) squares of differences in the form

E i( _g) (7)

where f is the normalized function in points i to be compared against function g in

the corresponding points, become x2 -distributed with N-i degrees of freedom, if the

weights are chosen as inverse square roots of functions g

X2 = (fi gi)2 (8)

Formula (8) is a starting point for nonlinear curve fitting by x2 minimum method

(Abramowitz & Stegun 1972). A successful application of this method in a noisy

environment is described in Routti & Prussin (1969).

If we cannot be sure, that the difference fi -gi is not totally random and normally

distributes, there is not much point of using x2 -distributions for comparison. To get

a simple quantitative measure for the goodness of predictions in ad hoc manner,

relative error indicators were calculated. For the upper layer temperature the variable

to consider is the temperature rise from the initial value 6(t) =T(t) - T(O) . The

thickness of the smoke layer hsmok and the depletion in the oxygen concentration AC2

were used to measure the goodness of the interface height and species predictions,

respectively. Interface height was here calculated using the density integral method.

The simplest way would be to calculate the average of the relative value of absolute

deviation

E 100% . s (t)6m(t) dt (9)

to o m (t)

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International Collaborative Project to Evaluate Fire Models for

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where to is the simulation time, 0s is the simulation result and is the measured

value. For applications in fire safety engineering this indicator alone would be rather

misleading, since errors at irrelevant times would gain much weight. For evaluating

the suitability of the technology for design purposes indicators are needed which give

weight for those values indicative for dimensioning. As for the selected variables the

large values are important, a weighted average Ema, is defined, where the relative

error weighted by the measured value.

t 7 a t |0 (t)dt

Eia. =100%- toI t ° 1 to

-f 0,,(t)dt (10)

to 0

to

l, (t) -Om wt)d

O m(t)dt

If low values are important for design, then the weighting by small values, like the

inverse of the measured value, would be appropriate.

The results are given in Table 2 for each code-scenario combination calculated. The

accuracy of the upper layer temperature predictions ranges from 17 to 42 %. Smoke

layer heights vary from 20 to 65%, and oxygen depletion from 7 to 76%. It is

possible to make some conclusions of the mutual order of the codes, but the order of

best codes varies from scenario to scenario. Based on the experience from these

simulations we could conclude that two-zone models predict e.g. heating of

structures for these types of fire scenarios at best at 20 % level of accuracy, if used

properly. The technology on smoke layer height and oxygen depletion prediction is,

on the average, slightly more inaccurate than for temperatures. CFAST and FIRST

performe better than average.

Table 2. Mean relative errors E,,,. (%) of the two-zone model results. ARG = Argos,

CFA = CFAST, MRF = MRFC, FIG = FIGARO, FW = FIREWIND, FST = FIRST,

FLS = FLAMME-S, FIS = FISBA.

Code ARG CFA MRF FIG FW FST FLS FIS Average

Variable

Tup B 25 13 14 14 21 21 48 26 23

TWp B2 27 27 25 26 NA 15 36 33 27

Tup B3 32 10 20 12 NA NA 41 35 25

Average 28 17 20 17 21 18 42 32 24

h 0,, B 72 23 14 27 20 19 25 19 27

hs,,, B2 69 62 81 88 NA 86 70 65 74

hs,,,,, B3 54 36 10 28 NA NA 51 32 35

Average 65 40 35 48 20 52 49 39 43

A0 2Bl a 33 2.7 2.0 3.0 7.4 1.7 1.1 1.8 3

A02 B2 37 38 36 31 NA 54 53 38 41

A02 B3 31 34 42 43 NA NA 175 67 65

Average 24 25 27 26 7 28 76 36 31

Only the first 20 minutes are taken into account.

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International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

CONCLUSIONS

A group of fire models was evaluated in the compartment fire scenario by comparing

the simulations against the experimental results. The main limitations of the

evaluation are due to the type of the fires, that were not well suited for the zone

models, and due to the limited resources of both the participants and the organisers of

the round robin. This report should not be considered as a thorough validation or

ranking of the codes or the users.

All of the codes had features that indicated a discrepancy with the experimental data

in the blind simulations, but which could be improved during the open round by

choosing alternate submodels and/or changing some optional parameters. According

to the summary of the quantitative error estimates the deviations from the

experimental data range from ±10 % up to a factor of 2. These deviations are of the

same order with the uncertainties related to the experimental measurements and input

data, especially the burning rate. The conclusion is that, for this kind of fire

scenarios, the expected uncertainty of the zone models is about 25 % in temperature

and smoke layer height predictions, if the codes are used properly. Where several

persons used the same code, the dependence of the results on the user was

demonstrated (not detailed here). It was indicated very clearly, that the user is the

most critical link in the chain of using computer fire simulation models for fire safety

engineering. This was true even though this group represented code developers, and

other well educated fire science and engineering practitioners. The effect is expected

to be much more pronounced when the whole group of computer fire code users is

considered.

ACKNOWLEDGEMENT

Authors wish to thank Dr. J. Barnett for his help and valuable contribution to this

report.

REFERENCES

Abramowitz, M. & Stegun, I.A. 1972. Handbook of Mathematical Functions, Dover,

New York, 1046 p.

Cox, G. 1995. Compartment Fire Modelling. In Cox, G. (ed.) Combustion

Fundamentals of Fire, Academic, London, pp. 329 - 404.

Cooper, L.Y., Harkleroad, M., Quintiere, J. & Rinkinen, W. 1982. An Experimentral

Study of Upper Hot Layer Stratification in Full-Scale Multiroom Fire Scenarios,

Journal of Heat Transfer. Vol. 104, pp. 741-749.

Cramer, H. 1946. Mathematical Methods of Statistics, Princeston University Press,

Princeston, 575 p.

Hagen, E. & Haksever, A. 1985. Contribution for the Investigation of Natural Fires

in Large Compartments. In: International Association for Fire Safety Science, Fire

Safety Science. Proceedings. 1st International Symposium. October 7-11, 1985,

Gaithersburg, MD. Hemisphere, NY. pp. 149-158.

C-71
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

He, Y., Fernando, A. & Luo, M. 1998. Determination of Interface Height from

Measured Parameter Profile in Enclosure Fire Experiment, Fire Safety Journal 31, 19

- 38.

Hostikka, S. & Keski-Rahkonen, 0. (eds.), 2002. Results of CIB W14 Round Robin

for Code Assessment, Scenario B, (to be published).

Janssens, M. & Tran, H.C. 1992. Data Reduction of Room Tests for Zone Model

Validation. Journal of Fire Sciences, Vol 10, pp. 528-555.

Kawagoe, K. 1958. Fire Behaviour in Rooms. BRI Report No. 27, Building Research

Institute, baraki-Ken, Japan, 74 p.

Mitler, H. E. & Rockett, J. A., 1987. Users' Guide to FIRST, A Comprehensive

Single-Room Fire Model, NBSIR 87-3595, National Bureau of Standards,

Gaithersburg, MD, 138 p.

Peacock, R. D., Reneke, P. A., Jones, W. W., Bukowski, R.W. & Forney, G. P.

1997. User's Guide for FAST: Engineering Tools for Estimating Fire Growth and

Smoke Transport, NIST SP 921, National Institute of Standards and Technology,

Gaithersburg, MD, 188 p.

Prahl, J. & Emmons, H.W. 1975. Fire Induced Flow Through an Opening.

Combustion and Flame, Vol. 25, pp. 369-385.

Quintiere, J.G., Steckler, K. & Corley, D. 1984. An Assessment of Fire Induced

Flows in Compartments, Fire Science and Technology, Vol. 4., No. 1, pp. 1-14.

Rockett, J.A. 1976. Fire Induced Gas Flow in and Enclosure, Combustion Science

and Technology, Vol. 12, pp. 165-175.

Routti, J.T. & Prussin, S.G. 1969. Photopeak method for the computer analysis of

gamma-ray spectra from semiconductor detectors, Nuclear Instruments and Methods

72, 125 - 142.

Tanaka, T. 1978. A Model on Fire Spread in Small Scale Buildings. Building

Research Institute, Japan, 44 p. + 47 p. App.

Tanaka. T. & Nakamura, K. 1989. A Model for Predicting Smoke Transport in

Buildings based on Two Layers Zone Concept, Report of the Building Research

Institute No. 123, 277 p., (in Japanese).

Thomas, P.H., Hinkley, P.L., Theobald, C.R. & Simms, D.L. 1963. Investigations

into the flow of hot gases in roof venting, Fire Research Technical Paper No. 7,

London, UK: Ministry of Technology.

Thomas, P.H. 1992. Two-Dimensional Smoke Flows from Fires in Compartments:

Some Engineering Relationships, Fire Safety Journal, Vol. 18, pp. 125-137.

C-72
International Collaborative Project to evaluate fire Models for NPP applications 2-3 may 2002

Fire zone model MAGIC:

The validation and verification principles

Bernard GAUTIER

6, quai Watier, 78401 CHATOU France

Abstract

This paper present the principles used in the validation and verification of MAGIC (EDF Zone

Model for simulation of fire in multi-compartment building). The general problem of validation

of zone model is discussed: validation of the sub-model (classic laws, empirical correlation,..)

and validation of the global model. Then a short presentation of MAGIC validation is provided:

principles, list of references, examples and future prospects.

Zone model approach of fire

A zone model results from the association of various sub-models:

- Integration of classical laws of physics

- energy and mass balance on different layers (homogeneous temperature and

concentrations, hydrostatic pressure, Perfect Gas assumption, etc..).

- simplified conduction in walls (1, 2 or 3D) or in some targets

- simplified radiation (semi-transparent assumptions in concave rooms)

- Semi-empirical models which can be found in fire source , plume, ceiling jet, convection

heat exchange coefficient, openings and vent, detection, suppression etc..

Due to this nature, we must first say a few words about sub-model validation.

Validation of the sub-models

The General laws are accepted by the scientific community. Empirical models have most of the

time been directly obtained from specific experiment, and have been qualified according to it.

Both have shown a certain accuracy and validity domain. (ex: Alpert correlation for ceiling-jet

was studiedfor r/H<3). The control of the right use of it must be done inside the code (for

instance: produce "warnings" when getting out of a validity domain).

So, the sub-model validation has to be considered during the zone-model conception.

Nevertheless, a sub-model used outside of its validity domain does not necessarily mean that the

global code results will not be acceptable. Moreover it is not possible to deduce the accuracy of a

code from its component ones. For those reasons, a global validation process remains always

necessary to validate the zone model itself.

C-73
International Collaborative Project to evaluate fire Models for NPP applications 2-3 may 2002

Validation of the global zone-model

The objectives of the zone model validation are the accuracy of the calculation data and the

validity domain. Both are linked: the acceptable accuracy domain is the validity domain.

Accuracy of the code seems impossible to determine theoretically, but it can be displayed by

confrontation to experimental fire, and estimated by this means. The criterion of "sufficient"

accuracy themselves, can be discussed.

The accuracy of a fire model, observed by comparison to experimental fires, remains quite rough

because too many parameters are involved in the fire process, and some complex phenomena

(combustion, mass flow, etc..) cannot be completely described. Furthermore, when using the

model in a real life risk study, the input control will be much worse and will interfere with the

calculation relevance.

Consequently, it is not crucial to get a very high level of accuracy when confronting experimental

and numerical results. The most important issues are to show that the code provides realistic

quantitative results in its current application field and respects the qualitative tendencies in the

fire dynamics and the significant effect of input variations.

In fact, the validation process is mainly demonstrative : it has to prove that, when the input

parameters are efficiently controlled, the code results are sufficiently realistic, in the range of the

code current application field. To make the demonstration efficient, the way of using the code in

this process must be similar to the way it is used for typical fire risk studies.

Validation "code of ethic"

If we had to list the most important issues of a "good" validation process, we would retain:

a- The quality of the reference tests:

To be demonstrative, the tests must be well known, approved and accepted by the

scientist community. Of course, the quality of the experiment is the main factor of this

acceptance, and has been discussed a lot (ex: ASTM E603)

b- The conditions of the code use:

To enhance the confidence and decrease the user effect, the input of the code during the

test must be clearly identified.

Any user modeling choice (fixed exchange coefficient., plume model, etc..) specific to the

calculation must be identified, or, as much as possible, avoided.

c - The Field covered by the tests:

The tests should cover the field of application of the code. First building configuration:

mall to medium scale compartment configuration, multi-compartment and large scale tests,

opened or confined condition for instance. Also, fire parameters: kinds of combustible, heat

release rates, etc..

The validation File of MAGIC

MAGIC is EDF code for determinist fire risk studies in NPP. The validation process of the code

is based on comparison to real scale fires : about 60 real scale fire tests are available in the base.

The file is used to define the validation domain of the code. This includes volumes from 10 to

1300 m3 (a 200 000 m3 case is at work), heat release from 100 kW to 2.5 MW (a 60 MW case is at

C-74
International Collaborative Project to evaluate fire Models for NPP applications 2-3 may 2002

work) , ventilated and post-flashover fires, Mono-compartment and multi-compartment varied

configurations, gas burner, liquid pool or solid fires, linear or axisymetrical fire source.

MAGIC has a large validation file, including among others the following references:

- Semi-natural fires in a room: Hognon B. CSTB/ DGRST-CSTE 1980 and Carmier, Curtat,

Hognon, Bertin - CNRS - CSTB 1984

- Semi-natural fire in a commercial hall corridor: N. C. Markatox, M.R. Malin "Int J Heat

transfer" Vol. 25 n 1 p. 63-75 BRE/FRS 1986

- Fires in ventilated room: (Alvares N.J., Hasegawa H.K., Lipska.Quin A.E.) Report UCRL53179, LLNL, Univ. of California, Livermore 1982

- Fire in a compartimented building (Cooper L.Y& al.) J. of Heat Transfer vol. 104 pp 714-749

NBS (1982)

- Real-size tests in multi-compartimented buildings : R.D Peacock, S. Davis, V. Babraukas

"Data for room Model Comparisons", Journal of research of the NIST, vol 96, N 04, 1991.

- Control-room tests FM/SNL: S. Nowlen NUREG/CR-4681 1987

- 20-foot separation tests ULISNL: NUREG/CR-3192 1983

- Large cable fire tests (2 compartiments) EDF-CNPP: CNPP TR 96 5045 P1 -1997

- CTICM Hotel-room: H. Lebotgne Test reprt 96S51 1 (1996) Linen-room (2 compartments,

post-flashover): H. Leborgne TR 97S031 (97) Large hall tests : TR 98-x-406 (97) ; TR 94-R242 (94)

MAGIC Code quality assurance

In accordance with the code Quality Assurance process, a selection of about 20 tests from the

validation file is used systematically to guarantee no regression of new versions. Any difference

between versions must be justified in the validation report. The code is always in standard

conditions when launching the reference tests. The validation process report is part of the

documentation and the tests can be easily re-played by the user.

At this point it is important to underline the differences between verification and validation of the

code: the verification of the code specification consists in controlling the respect of sub-model

specifications, the different parts (user interface functionalities, calculation options, etc..). It is a

different task than validation, also done through the MAGIC code Assurance Quality process.

This aspect must not be neglected because the validation tests are not necessary covering all the

code possibilities.

Direct comparison of numerical and experimental data

The model necessary input for comparison are: the building materials and configuration,

boundary conditions, the combustible properties and location and the mass loss rate scenario.

The commonly available data for comparison are (in decreasing frequency) : local temperatures,

average temperatures, heat exchanges on targets obtained on fluxmeters, interface height (which

estimation may follow different point of view) gas velocities, species concentrations (02, C02 ,

CO, CnHm NOx, SOx,..), pressure, mass flow through openings.

The first comparison is generally done on gas temperature and fluxes, considering at less the

range and delay of the peaks. Those variables represent the thermal boundary condition for the

C-75
International Collaborative Project to evaluate fire Models for NPP applications 2-3 may 2002

materials to protect. Nevertheless, they are not easy to obtain, being very unstable, linked to mass

flows and radiation. In some cases it seems that internal temperature of targets could be an

interesting alternative to develop. The other measurements are less frequent, some like pressure

or mass flows are rarely provided.

The comparison is first a "visual" analysis of differences. Numerical analysis can be done, based

on relative difference (ex: (Tmes-Tcalc)/ (Tmes-To) as a error percentage). Sensitivity to input

variation has been done in the process of qualifying the physic model adjustments.

,CONCENTRATION 02 ZC TEMPERATURE ZC

a ~~~~~~~~~~~~~~~~target 1 b.t Mbm

0 250 00iOCO~

I L/>e...... . . . > d 0 .............. asoO I oDo

or Ul,__t1,,, ok~~~~~~~~~~~~~~~~~~~~~~~000 LE0D00EW0A,,AP, 1 .

am ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I 2 .3+0

anS. o . _ C _ wtWa0 Lo aao baw Iot1 V, 131 ad

Mono-compartment test (CSTB 84)

figure 1: comparison of numerical and experimental data

Future prospects

The validation process of code MAGIC is in constant progress. The file is to be reinforced by

tests focusing targets temperature. Those variables fluctuate less than gas temperature and are more

relevant for risk studies (dysfunction, ignition). Tests are to be done in 2002. Pressure measurement

and interaction with ventilation system will be studied through specific tests, also programmed in

2002. The next field of investigation should concern fire suppression effect and complex multiroom configurations: horizontal openings and duck-board.

Conclusion of EDF experience

The validation file is the key of code acceptance. Comparison to real-size and a large field of

experiment data is the only way to guarantee an efficient demonstration of the code efficiency.

The experimental tests and measurement must be of good quality, available to and accepted by the

scientific community. At last, the process of code validation must be independent of modeling choices and

available to the final user.

The results obtained with MAGIC on a selection of experimental data has allowed us to get

confident for its use in a large range of volumes, heat release and configurations.

C-76
CFD SIMULATION OF A3.5MW OIL POOL FIRE IN A NUCLEAR POWER PLANT

CONTAINMENT BUILDING USING MULTI-BLOCK LARGE EDDY SIMULATION

Jason Floyd

Building and Fire Research Laboratory

National Institute of Standards and Technology

100 Bureau Drive Stop 8663

Gaithersburg, Maryland, 20899, USA

P: (301) 975-6855, F: (301) 975-4052, jason.floyd@nist.gov

Introduction

Implementing performance-based regulations require the presence of analytical tools and

analytical methods [1]. In the case of fire safety regulation, there are three categories of tools available

for demonstrating the performance of a structure and its fire protection systems [2]. These categories

include hand calculations, lumped-parameter models, and field models. For most scenarios, one of the

first two methods should be all that is required to demonstrate performance. However, there will be

instances where neither of the first two methods will be enough. Situations, for example, with highly

complex geometry or where detailed knowledge of spatial effects are needed may require the use of field

models. In some sense, this is unfortunate, since the use of field models requires a much large

expenditure in terms of both time and computational resources [3]. However, the time required to use a

field model can be greatly reduced by the use of a multi-block solution scheme. To demonstrate the

potential of a multi-block field model for fire simulation, a multi-block version of FDS was used to

simulate a portion of an oil pool fire experiment that took place in the HDR facility in Germany [4].

HDR Facility

The HDR test facility [slide 7] was the containment building from a decommissioned nuclear

reactor in Germany. The facility was a cylinder 20 m in diameter and 50 m in height and was topped by a

10 m radius hemispherical dome. The facility had eight levels and over 60 compartments. Multiple

vertical flowpaths were present in the form of two axially located sets of equipment hatches, two

staircases, and an elevator shaft. The total free air volume in the facility was 11,000 m3 of which the

dome contained 4,800 m3 [5].

The test simulated for this work is test T52.14 [slides 8-11] an oil pool fire test done in 1987 that

occurred on the level below the dome. The T52.14 test used a 2 m pool of Shellsol-T, a liquid

hydrocarbon, placed on a weighing platform in a firebrick lined compartment beneath the dome. This

compartment was connected to a second firebrick lined compartment beneath one of the equipment'

hatches. The hatches both above, leading to the dome, and below this compartment were open. The test

started by igniting 50 liters of oil followed by adding additional oil at a rate of 5.6 L/min once the initial

volume nearly depleted as determined by the weighing platform. The entire facility was instrumented

with 56 velocity sensors, 155 thermocouples, and 43 gas sampling lines [5].

Multi-block FDS

FDS, Fire Dynamics Simulator [slide 3] has recently been released as version 2 by the National

Institute of Standards and Technology [6]. FDS is a CFD model that solves the low-Mach number form

of the Navier Stokes equations using a Smagorinski turbulence model. The FDS uses a simple mixture

fraction combustion model [7] where the user can define basic parameters of the fuel chemistry. The FDS

radiation model is a finite volume method radiation solver for the gray gas radiation transport equation

[8]. RADCAL [9], a narrow band radiation model, is used to determine absorption coefficients based on

the local mixture fraction and temperature. In both version 1 and version 2 of FDS, a single-block solver

was implemented.

C-77
Single-block solvers [slide 4], common in many field models, use one computational grid that

spans the entire domain of interest. For many fire problems, this is an efficient method of defining the

computation. In fire simulation, a lower grid resolution is needed to track smoke movement than is

required to adequately simulate the region of active combustion. Thus, with one grid being used, the

requirement to finely node the fire means that many more cells than necessary are located in regions

where only smoke transport is occurring [slide 5]. Also, if more than one compartment is being

simulated, than there is the potential for many grid cells to be defined as dead space in order to encompass

the compartments [slide 6]. Both situations, large numbers of dead cells or higher than needed resolution,

increase both the time required for a computation and the computational resources needed.

In a multi-block solver, the user may define more than one computational grid. Thus a fine grid

could be defined for the region of combustion and a coarser grid defined for non-combusting regions.

Also each compartment could have a separate grid defined for it, eliminating the need to carry a large

number of dead cells. However, as with many numerical schemes, while multi-block solvers remove

some computational effort by eliminating grid cells, they do increase the overall computational overhead

for a problem. This is because the solver must expend effort to share information between grids at their

shared boundaries. This extra effort, however, can be easily outweighed by the time saved be reducing

the number of nodes. As part of the development effort for the next release of FDS, a multi-block solver

has been added.

Multi-block FDS Model of HDR Test T52.14

The T52.14 test was simulated using a multi-block version of FDS. The region modeled included

the entire dome and the two firebrick lined compartments on the level beneath the dome, slides 17 and 18.

An open vent located beneath the room adjacent to the fire room and in the dome floor opposite the fire

room simulate the connections to the remainder of the HDR facility. A reasonable nodding of the fire

room entails using grid cells on the order of 10 cm in size. Since the computational domain is 20 m x 20

m x 26 m, this would require over 1.2 million grid cells. However, this would result in many dead cells as

only a small fraction of the space beneath the dome is being simulated, the fire room and its adjacent

space. Also, in the dome there is no combustion occurring. Thus, the dome does not need to be as

densely noded as the other two compartments. Instead three grids were used: one for the fire room, one

for the room adjacent to the fire room, and one for the dome. The first two grids had a 10 cm resolution

and the dome grid had a 25 cm resolution. This resulted in the use of 600,000 grid cells, a savings of

50%. A second FDS run was performed with a grid at 3/4 the linear resolution. [slides 13,14]

The FDS simulation was done for the steady-state portion of the test and was run until

temperatures at the upper dome measurement grid were observed to reach a quasi-steady state solution.

Both cases were run on a 2.2 GHz, Pentium IV, Linux machine. The full resolution case required 7.5

minutes of CPU time to one second of realtime, and the 3 resolution case required 2.5 minutes/s. [slide

151

Results

Computational results of the two models show that the multi-block version of FDS performs well

for a number of parameters. FDS results for the fire room [slide 16] compared to both the collected data

and some hand calculations show that FDS is accurately predicting the major conditions of the fire room.

One great advantage of a field model, the ability to generate 3D data for visualization can be seen in the

image showing the calculated flame sheet superimposed on a temperature contour centered over the pool

of oil [slide 17]. This image shows that the flame sheet is entirely within the room; however, with the fire

size being simulated one would expect that external burning would be occurring. DS would appear to

be under predicting the flame lengths. In the door way, FDS matches well the measured velocity profiles;

however, temperatures are not as well predicted in this location [slide 18]. The measured data shows

flame temperatures, which would suggest external burning. Since FDS is not predicting external burning,

its doorway temperatures are low. An animation of the entire plume structure shows how the velocity is

C-78
smoothly continuous across all three grids [slide 19]. An indication that the multi-block solver is

handling the grid transition well.

Comparisons of temperatures in the hatch leading to the dome show that FDS is underpredicting

temperatures at this location by 100 K [slides 20,211 and that FDS is predicting the plume in a slightly

different location in the hatch. The velocities, however, appear to be reasonably well predicted by FDS

[slide 22]. Some of these differences are probably due to the external boundary conditions. DS

simulates these as open boundaries, whereas in the HDR facility the two external openings were actually

hydrodynamically coupled. In the dome, comparisons of temperatures [slides 23,24] show that FDS is

now over predicting the bulk temperature by 30-40 K, but matching well the plume center temperature.

This may be due to FDS not transferring enough heat to the dome structures as compared to the test. The

predicted velocities [slides 25,26] indicate that FDS is predicting a somewhat narrower plume, which

could result from the numerical grid and a slightly different location of the plume centerline. However,

this measurement location is close to 20 m from the fire, and the EDS plume center is <2 m from the

position given by the data. An animation of the plume in the dome is shown. [slide 27]

Concluding Remarks

A multi-block version of FDS clearly has tremendous potential as a tool for simulating fires in

large, multi-compartmented structures. The current prototype version maintains well flows across grid

boundaries, even for grids of varying mesh sizes. Energy fluxes across the boundary also appear to be

well maintained. Lastly, FDS was able to accurately predict the location of the plume after 20 m of travel

from the fuel source.

References

[1] Bertrand, R., and Dey, M., 2001, "International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications: Summary of 2nd Meeting," NUREG/CP-0173, US Nuclear Regulatory

Commission, Washington, DC.

[2] Floyd, J., 2002, "Comparison of FDS and CFAST for Fire Simulation with HDR T51 and T52 Tests,"

NISTIR-6866, National Institute of Standards and Technology, Gaithersburg, MD.

[3] Floyd, J., 2002, "Numerical Simulation of a Compartment Fire in a Nuclear Power Plant Containment

Building," ICONE10-22299, Proceedings of the 10t International Conference on Nuclear Engineering,

ASME, Alexandria, VA.

[4] Schall, M., and Valencia, L., 1982, "Data Compilation of the HDR Containment for Input Data

Processing for Pre-Test Calculations", PHDR Working Report 3.143/79, Project HDR Nuclear Center,

Karlsruhe, Germany.

[5] Floyd, J., and Wolf, L., 2000, "Evaluation of the HDR Fire Test Data and Accompanying

Computational Activities with Conclusions From Present Code Capabilities, Volume 4: Test Series

Description and CFAST Validation for T52 Oil Pool Fire Test Series," NIST GCR 01-809, National

Institute of Standards and Technology, Gaithersburg, MD.

[6] McGrattan, K., Baum, H., Rehm, R., Hamins, A., Forney, G., Floyd, J. and Hostikka, S., 2000, "Fire

Dynamics Simulator (Version 2): Technical Reference Guide." NISTIR-6783, National Institute of

Standards and Technology, Gaithersburg, MD.

[7] Floyd, J., Baum, H., and, McGrattan, K., 2001, "A Mixture Fraction Combustion Model for CFD Fire

Simulation," Proceedings of the International Conference on Engineered Fire Protection Design, Society

of Fire Protection Engineers, Bethesda, MD.

[8] Hositkka, S., and McGrattan K., 2001, "Large Eddy Simulation of Wood Combustion," Franks, C.

ed., Proceedings of Interflam '01, Interscience Communications, London, England, Vol 2., pp 755-765.

[9] Grosshandler, W., 1993, "RADCAL: A Narrow-Band Model for Radiation Calculations in a

Combustion Environment," NIST Technical Note 1402, National Institute of Standards and Technology,

Gaithersburg, MD.

C-79
NIST Large Fire Laboratory

George W. Mulholland and David Stroup

The purpose of the NIST Large Fire Laboratory (LFL) is to apply quantified measurements, realtime analysis, and large area diagnostics to validate models for fire phenomenon including fire

dynamics, detection, and suppression. The LFL is also used for obtaining product yield data and

HRR data for model input for fire models and for carrying out large scale tests requiring

specialized instrumentation and data interpretation. An overview of the LFL development,

recent experiments and planned enhancements will be described below.

Capabilities of the Renovated Exhaust System

In 2000, the exhaust facility for our large scale facility was upgraded to remove smoke

particulate using a baghouse and acid gases with a scrubber. In addition, the exhaust capacity of

the facility was increased more than 20 fold to a flow of 42 m3/s. The increased flow allows fire

experiments to be carried out with heat release rate (HRR) as large as 10 MW for the 9 m x 12 m

hood. This is near the peak HRR for a small house. A 6 m x 6 m hood is available for fire tests

as large as 3 MW. In addition there are two smaller hood assemblies with dimensions of 2.5 m

x 2.5 m and 1.2 m x 1.2 m that in the future will allow smaller bums when connected to the

exhaust system. The full suite of hoods/exhaust capabilities will allow fire experiments ranging

in size from about 5 kW to transient peak HRRs as large as 15 MW. The total high bay floor

space for enclosure assemblies is 9 m x 30 m. The height of the base of the 9 x 12 m hood is

6.4 m allowing fire tests for a two story structure.

Quantitative HRR Calorimetry

The heat release rate (HRR) is the single most important quantity characterizing the hazard

resulting from the burning of a given fuel package. It will determine the temperature within the

enclosure, and the concentration of the combustion products including the smoke particulates

and the toxic gases (CO and HCN) will be proportional to the HRR. A major focus of the LFL

for the past two years has been the accurate measurement of HRR including a quantitative

uncertainty assessment.

Our method is based on oxygen consumption calorimetry. The scientific basis of the method is

that the HRR is proportional to the oxygen consumption together with the finding that for most

materials found in buildings the heat of combustion per kg of oxygen consumed, H,, is 13.1 MJ.

The equation for the HRR is given by':

Q = (X (0 2) - X(0 2 )HCp(0 2)1V

where X(02 ) is the oxygen mole fraction, P(02) the density of oxygen, is the volumetric flow of

ambient air into the combustion zone. There are a number of complications in performing

quantitative measurements. First, the value of Hc is affected by incomplete products of

combustion such as CO. Secondly, the exhaust flow is measured rather than the inlet ambient

flow and the flow must be corrected to account for the changes in stoichiometry as oxygen is

C-81
consumed and CO, CO2, and H 20 are produced. Thirdly, the uncertainty in the measurement

increases for small fire sizes because of the small change in the oxygen concentration.

Our methodology for performing the measurements is to collect all the combustion products in

the 6 m square hood, pass the flow through a flow straightener, measure the duct flow velocity at

eight locations using bi-directional probes, and sample the smoke at multiple locations using a

sampling probe cross. A high flow diaphragm pump rapidly directs the smoke flow to the 02,

CO2, and CO analyzers from the sampling location on the roof of the Laboratory through a

heated line about 20 m to the instrumentation room on the first floor. The moisture is removed

with a dry-ice trap before the gas enters the analyzers. There is approximately a 15 s delay from

the time the smoke leaves the flame until the gas sample is detected by the gas analyzers and this

delay time is compensated for in the data analysis. During the upcoming year a helium tracer gas

method will be use for accurately characterizing the duct flow.

Three additional capabilities critical to enhancing the accuracy and usefulness of our heat release

measurements are a calibration burner, a data acquisition/control system capable of providing

nearly real-time output, and a natural gas heat of combustion "meter."

Calibration Burner

The burner consists of 11 tubes in a 1.6 m x 1.2 m planar array with holes spaced approximately

every 2.5 cm along the tubes Valves control the fuel flow to various sections of the burner so

that the flame dimensions will be similar to that of a buoyancy dominated diffusion flame as the

flow is increased. The Fire Dynamics Simulation Code was used in designing the burner. The

heat of combustion of the natural gas used by burner is measured by an accurate gas calorimeter.

Other important design features are the use of industrial control devices for monitoring and

controlling the flow rate and for shutting off the flow if the flame extinguishes. The flow

monitoring device is calibrated at the NIST flow metering facility. The burner has been

successfully tested over the heat release range from 50 kW to 6 MW.

Data Acquisition System

A dual processor workstation computer with National Instruments' hardware has been assembled

with a LabVIEW program designed to compensate for different measurement times to achieve

near real-time analysis and display of processed data. In typical use, 1 second averages for 60

channels are scanned at 200 Hz during a one hour test. In addition, the system can be used to

control the fuel flow to have step changes or quadratic time dependence to simulate the typical

growth rate for fires. The controlled burner and the heat release apparatus has been used for

assessing the repeatability of the HRR calorimeter for fire sizes of 50 kW, 700 kW, to 3 MW.

The hood was operated at two exhaust flow rates and 3 repeat measurements were made for each

condition. For the larger two HRRs, the measured value agreed with the calibration burner to

within 2 % and the measurement repeatability was within 6 %. The variation in the smallest

' Certain commercial equipment or materials are identified in this paper to specify adequately the experimental

procedure. Such identification does not imply recommendation or endorsement by the national institute of

Standards and Technology , nor does it imply that the materials or equipment are necessarily the best available for

the purpose.

C-82
HRR was over 20 % and found to be a result of drift in the output of the oxygen meter. Efforts

are underway to correct for the background drift of the analyzer and to purchase a lower drift

oxygen meter.

Recent Large Scale Tests

The following major studies have been carried out in the LFL since its renovation: bed fires,

smoke detector study, and sub-lethal toxicity measurements. These studies illustrate the range of

capabilities in the LFL.

Bed Fires

The objective of the bed fires, sponsored by the Sleep Products Safety Council, was to quantify

the relation between the heat release rate from a burning bed and the distribution of heat flux to

the space around it2. Such heat fluxes might ignite other objects, leading toward room flashover.

The information was in turn used to infer the largest tolerable bed fire that would both preclude

other item ignition and minimize casualties due to heat and toxic gas exposures. The LFL six

meter hood provided a unique capability to measure a very diverse range of bed fires which

varied 100 kW to 5 MW.

Smoke Detector Study

In co-operation with the United States Fire Administration (USFA), other sponsors, and U.S.

Consumer Product Safety Commission (CPSC), NIST coordinated the evaluation of current and

emerging smoke alarm technology responses to common residential fire scenarios and nuisance

alarm sources. The measurements were all carried out in a manufactured home contained within

the LFL. Unique capabilities provided by NIST include the detailed characterization of the

environment near the detector including the temperature, flow, gas concentrations, smoke

particle concentration, particle size and optical density. The quality of the data was greatly

enhanced by fully characterizing the response of the 150 gas and particle detectors used in the

study with the unique Fire Emulator/Detector Evaluator developed at NIST.

Sub-lethal Effects Experiments

This study funded by the Fire Protection Research Foundation of National Fire Protection

Administration is focused on characterizing the yields of toxic gases and smoke particulate

produced by both pre-flashover and post-flashover fires. The room contents included electric

cables, sofa mockups, or bookcases with and without a sheet of PVC. The test required

characterization of the environment at two sampling locations with sensors for temperature (bare

and aspirated thermocouples), velocity (bi-directional probes). Standard gas analysis included

CO, CO2 , and 02. An innovative feature of the experiments was the use of multiple FTIRs

monitor the concentration of additional gases, such as HCl, HBr, HCN, and acrolein. In addition,

for the first time at NIST, smoke was sampled in the upper layer leaving the doorway during

flashover conditions. The smoke sampling included a temperature controlled filter assembly and

a quantitative method for removing smoke deposited on the walls of the sampling tube.

C-83
Measurements at upstream and downstream locations enable estimation of the loss of smoke

components to the walls.

Future Capabilities

We plan to develop the following challenging capabilities during the next year: soot volume

fraction in the hot upper layer, heat transfer measurements to steel elements, to cable trays, and

to the walls, and surface temperatures for metals, insulating materials, and cables.

There is also great interest in the application of large area imaging optical diagnostics to large

scale fires. The current status of projects for measuring water spray and doorway flows are

briefly described below.

Water Spray

An advanced measurement method is under development, with the goal of providing

simultaneous measurement of sprinkler spray drop size and velocity. The method illuminates a

0.5 m by 0.5 meter area of the spray field with laser pulses, and uses laser induced fluorescence

to image the droplets. Velocity is determined by analysis of the distance between two-color

droplet pairs, and droplet size is determined from the size of the droplet images. Droplet sizes

over the range of approximately 200 m to 3000 Am can be measured, with low levels of

uncertainty. Droplet velocities are accurately measured over the range 0.5 m/s to 50 m/s.. Data

has been collected and analyzed data for 27 different parameter sets for an axially-symmetric

sprinkler. The long term plan is to characterize the droplet size and velocity in the LFL for a

sprinkler interacting with a fire plume.

Particle Imaging Velocimety

Particle Image Velocimetry (PIV), a non-intrusive laser-based measurement technique, is being

applied to measure two-dimensional fields of velocity vectors in the lower layer of a fire-induced

doorway flow. The technique significantly improves upon the spatial and temporal resolution of

traditional bi-directional probe measurements. Two-dimensional images of gas velocity vectors

were recorded last year using the PIV technique for a 26cm x 26cm region along the axis of a

surface opening for ambient conditions. The data included instantaneous velocity field,

instantaneous vorticity field, and mean flow streamlines, respectively. This year The PIV system

was upgraded to 3D so that all three components of the velocity vector can be measured in a

single acquisition. A reduced scale buoyant He plume and enclosure were designed and

fabricated. It is anticipated that measurements will be completed this fall and the measurement

of doorway flows for a full scale experiment are planned for 2004.

l Parker, W.J., "Calculations of the Heat Release by Oxygen Consumption for Various Applications," J. Fire

Sciences, 2, 380-395 (1984).

2 Ohlemiller, T.J. and Gann, R.G., "Estimating Reduced Fire Risk from an Improved Mattress Flammability

Standard," NIST Technical Note 144b, 2002.

C-84
A oCoaYS

Technical Note

TN - KLH 2/2002

Fire Benchmark #2

Part 1:

Fire in a large Hall

CFX and COCOSYS

Preliminary Results

- DRAFT VERSIONW. Klein-HeBlling

April 2002, Draft Version

C-85
Content

1 Introduction ......................... 1

2 Nodalisation and used Models ......................... 1

3 Preliminary results ........................ 4

3.1 Case 1 ......................... 4

3.2 Case 2 ........................ 11

3.3 Case 3 ........................ 18

3.4 Comparison between the cases ........................ 23

4 Conclusions - Next steps........................................................................ 25

C-87
List of figures

Fig. 2-1 COCOSYS Nodalisation: side view .................................................. 2

Fig. 2-2 COCOSYS Nodalisation: top view .................................................. 3

Fig. 2-3 COCOSYS Nodalisation .................................................. 3

Fig. 3-1 Case1: temperatures at lower part of tree 1 ................................................ 5

Fig. 3-2 Casel: tempertures at upper part of tree 1 ................................................ 6

Fig. 3-3 Casel: temperatures at lower part of tree 2 ................................................ 6

Fig. 3-4 Casel: temperatures at upper part of tree 2 ............................................... 7

Fig. 3-5 Case1: Temperatures at lower part of tree 3 ............................................... 7

Fig. 3-6 Casel: Temperatures at upper part of tree 3 .............................................. 8

Fig. 3-7 Casel: Comparison between the different variations of calculation ............ 8

Fig. 3-8 Case1: Plume temperatures .................................................. 9

Fig. 3-9 Visualisation of the fire plume (temperature) in COCOSYS ........................ 9

Fig. 3-10 Visualisation of the fire plume (temperature) in CFX .10

Fig. 3-11 Casel: Interface height .10

Fig. 3-12 Casel: Upper layer temperature .11

Fig. 3-13 Case2: Temperatures at the lower part of tree 1 ................................... 12

Fig. 3-14 Case2: Temperatures at the upper part of tree 1 ................................... 13

Fig. 3-15 Case2: Temperatures at the lower part of tree 2 ................................... 13

Fig. 3-16 Case2: Temperatures at the upper part of tree 2 ................................... 14

Fig. 3-17 Case2: Temperatures at the lower part of tree 3 ................................... 14

Fig. 3-18 Case2: Temperatures at the upper part of tree 3 ................................... 15

Fig. 3-19 Case2: Temperatures inside the plume .15

Fig. 3-20 Case2: Heat flow to the wall structures .16

Fig. 3-21 Case2: Calculated mass flow rates through the infiltrations .16

Fig. 3-22 Interface height in case 2 .17

Fig. 3-23 Upper layer temperature in case 2 .17

Fig. 3-24 Case3: Temperatures at lower part of tree 1 ................................ 18

Fig. 3-25 Case 3: Temperature at upper part of tree 1 ................................ 19

Fig. 3-26 Case 3: Temperature at lower part of tree 2 ................................ 19

Fig. 3-27 Case 3: Temperature at upper part of tree 2 ................................ 20

Fig. 3-28 Case 3: Temperature at lower part of tree 3 ................................ 20

Fig. 3-29 Case 3: Temperature at upper part of tree 3 ................................ 21

Fig. 3-30 Case 3: Plume temperatures .21

Fig. 3-31 Case 3: Injected and burned heptan mass .............................. 22

C-88
Fig. 3-32 Case 3: Interface height ........................ ................................... 22

Fig. 3-33 Upper layer temperature............................................................................ 23

Fig. 3-34 Calculated heat release rates for the 3 cases ........................ ................... 24

Fig. 3-35 Comparison of the measured and calculated temperatures at T1.10 ........ 24

Fig. 3-36 Comparison of CFX and COCOSYS for all cases ..................................... 25

C-89
1 Introduction

In the frame of the "International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant Applications" a second benchmark exercise have been performed. In

this exercise different pool fire experiments in a large hall have been investigated. In

this technical note first results of performed COCOSYS calculations and some CFX

preliminary results are discussed.

COCOSYS is a so-called lumped-parameter code. To simulate the local conditions

(natural convection, temperature stratification) the fire hall is divided into a quite high

number of control volumes. The main idea is to have for each temperature measurement a separate control volume and to have separate control volumes around the fire

plume, the ventilation system and the doors.

CFX is a CFD program. The k-e model has been used for the simulation of turbulence.

For the reaction the eddy-break-up model has been used. CFX has a separate radiation model RAD3D to consider the heat distribution of the flame.

The CFX calculations have been performed by M. Heitsch. The results of

COCOSYS and CFX are preliminary.

2 Nodalisation and used Models

For COCOSYS a detailed subdivision of the fire hall has been used. Fig. 2-1 to Fig.

2-3 show the nodalisation of the fire hall. With this subdivision nearly all temperature

measurements have a separate control volume. There a direct comparison between

experimental measurements and calculated results is possible. The total number of

control volumes is 543.

The control volumes above the pool have an area of 6 M2 . This leads to some averaging of the temperatures in the fire plume. COCOSYS itself has no specific plume

model.

C--91
The flow between the control volumes is mainly buoyancy driven. A momentum balance is not calculated.

For the calculations the given pyrolysis rates are used. In the first calculation the calculated temperature has been calculated to high. Therefore the reaction rate above the

pool has been reduced by an additional factor FEFF of 60%. The remaining unburned

heptan may be burned in upward direction. 20% of the reaction heat is distributed by

radiation to the wall structures. The view factors used have been calculated by the new

grid generator for COCOSYS. For the heat exchange between the walls and atmosphere the specified heat transfer coefficient and the COCOSYS heat transfer models

for free convection have been used, respectively.

In the CFX calculations following standard models have been used:

- for the simulation of combustion the eddy-break-up model (for each cell)

- k-e model for turbulence

- the radiation is simulated by RAD3D

- the Magnussen-Model for the simulation of soot behavior

4 4.9

I -I _ _ _ I

.9 . i

~Is

obsucti I .4~~~~~

r----_

9.4 Ados

Dbs~2

12

i. z

Y 

2.8 87.2

_ 89 

9.1

Fig. 2-1 COCOSYS Nodalisation: side view

C--92
1s

132

Ob tcwl 2 .

8 2.SI absucti=c2

fineta.-.

16

I

27

Fig. 2-2 COCOSYS Nodalisation: top view

Fire benchmark #2

COCOSYS nodolisotion

Fig. 2-3 COCOSYSNodalisation

C-93
3 Preliminary results

In the following sections the preliminary results will be discussed. The figures show the

actual status of the COCOSYS results for the three specified cases of part 1 and some

CFX results for comparison reason.

3.1 Case 1

Fig. 3-1 to Fig. 3-6 show the comparison between the optimal COCOSYS calculation

and the measurements at the 3 temperature trees. The quality of the results is quite

well. The stratification of the temperatures at the upper measurement points is calculated somewhat too high. The main reason is the missing momentum balance in the

COCOSYS calculation. The mass flow between the control volumes is mainly induced

by the buoyancy leading to stratified results.

It has be pointed out, that the reaction efficiency is adjusted to the temperatures. Unfortunately there is no additional possibility to check this modeling assumption, like concentration measurements or measurement data of the temperature decrease after the

burning process.

Fig. 3-7 shows the temperatures at T1.6 and T1.10 for the different variations of

COCOSYS calculations and the CFX results. The CFX result is similar to the COCfull

case of COCOSYS. Both calculation assume a full reaction of the heptan. The differences between the green (COCbase) and red (COCopt) curve results from the different

assumptions for the heat transfer to the boundary and the infiltration. In the COCopt

case the COCOSYS heat transfer models for free convection are used, the walls are

handled non-adiabatic on the outer side and a the half of the infiltration from the upper

position are shifted to the top of the roof. Assuming the full reaction the calculated temperatures are about 50 K too high. The influence of the different assumptions for heat

transfer and infiltration leads to a temperature decreasing of about 15 to 20 K. Therefore the main effect results from the decreasing of the reaction efficiency.

The beginning of the temperature decrease after the burning process shows the right

behavior. But the time period is too short, to conclude that the calculated heat loss into

the walls and through the infiltration is simulated correctly.

C-94
Fig. 3-8 presents the comparison of the plume temperatures TG1 and TG2.

COCOSYS has no specific plume model. As already mentioned the plume is simulated

of a column of control volumes above the pool. The area of these volumes is 6 M2 .

This lead to an averaging of the calculated temperatures. In the CFX calculation the

temperatures are much higher and the behavior seems to be more realistic, also the

temperature level is somewhat to high. A three-dimensional impression of the fire

plume can be drawn from Fig. 3-9 for COCOSYS and Fig. 3-10 for CFX. Both figures

show the temperature distribution in the middle yz-plane.

In the following figures the average values are presented. These have been calculated

according the formulas specified in the benchmark description. Although the correspondence between the measured and calculated temperatures are quite well, the calculated interface height is too low (red curve).

COCOSYS: Fire benchmark #2 casel

U

I0.

E

0

0

0

F140 _ ...............................

CA ASZXCE

CAL_GAS_Z_XA

120 X CAL GAS Z - ........... ........ *CAL GAS..ZZK

A CAL GASZ_YM

100 A T1.2 -------------

* T1.3

* TIA.

60-- --_ag

40_- ' - - ' =

20 __I- - -_ -

I 0 

0 so 100 1S0 200 250 300

time t(s)

350 400 4S0

Fig. 3-1 Case1: temperatures at lower part of tree 1

C-95
COCOSYS: Fire benchmark #2 case1

I-I.

8

a

E

I.-

140 ...... t.... ...........

1 CALGASZYM -

_* CAL_GAS_Z_EP i E i 

120 x CALGASZKP. .......... ...........

oCAL .A-Z OP

T1.6 ' .-. ,

A TI.5

100- T ATI.8 1 7 . ....., ......-- _~i -~---------- *

0 ....... r. "- n m- " 1 _ m_ 1

60 .......-- > W3 Y -~~~~--- -~~-

20 .......... __.. _ .....__..._...... ......... ...... ....... ....

0

0 50 100 150 200 250 300 350 400 450

time t(s)

Fig. 3-2 Casel: tempertures at upper part of tree 1

COCOSYS: Fire benchmark #2 casel

1 00

I

r 80 4)

E

4)

4) 60

I--

0 50 100 150 200 250 300 350 400 450

time t(s)

Fig. 3-3 Casel: temperatures at lower part of tree 2

C-96
COCOSYS: Fire benchmark #2 case1

E4I.-

E

4)

4)

I140 -- ----- .... ---- -- ..

*CALASP

120 *CALPAS Z Z

OCAL-G9ASZDQ

*T2.6

A T2.7

100 *T2.8

40

20

0 r.mr ,---Ill1r--,,i --r- r ""-T"in 'I "i" '- "" -nn'-n6r

0 S0 100 1S0 200 250 300

time t(s)

Fig. 3-4 Casel: temperatures at upper part of tree 2

350 400 450

COCOSYS: Fire benchmark #2 case 1

I.

03

E

03

03

I.-

140 -- _._ _._. ... . .... .... .... _--.-- -.

A CAL GAS Z TE | i * 

CALGASZUF

120 . *CAL GASZKJ .......... .. °CALGASZQL

A CAL GASZPN

* T31

100 A T3.2 .* ........... ................ ..... ... ........

*T3.3

80 T354 80 .V TT3.5 ........ ..-- ------ ---- -......... -_ - -

60

40-

20-

0 - . . .. .

0 50 100 150 200 250 300 350 400 450

time t(s)

Fig. 3-5 Casel: Temperatures at lower part of tree 3

C-97
COCOSYS: Fire benchmark #2 casel

j - ! .- i _ _ _ _ _ 4 An I _ _ _ L -

120 =

a CALGAS_Z_PN

CALGAS_Z_ZR

x CALGAS Z BS

* CALGASZVS

u T3.6

A T3.7

+ T3.8

* T3S

V T3.10

i-- -------- .......... . . ... . ....

i

I

0.

E

4)

,eCD)

I100 -: ...._..____.... ..--. -- -. ................................................... 

80- -_.._.--_...,.__-__....

40 .................

0 .. ---.--- ----- -................. ............................ ........... __v 

20-. ..... _,_.__ ._j.__.____j_

0.'" r~rr ~m - 7 .i"" "t'" ,"~ r r '~~r~ T ' 

0 50 100 150 200 250

time t(s)

300 350 400 450

Fig. 3-6 Case1: Temperatures at upper part of tree 3

COCOSYS: Fire benchmark #2 case1

250 -

O COCopti GASYM

COCoptiGASZOP .

200 . COCbaseGASM --.............. - .. COCbase GASZ_OP

COCfuIlGASZYM

- COCfuIlGASZOP

T1.6S

'- 150 V T1.10 4) Ncfxrl .6

0 cfxT1 0O

a.

S

1 O - .......... ............. .................... ._.

P)

0 So 100 1S0 200 250 300 310 400

time t(s)

Fig. 3-7 Case1: Comparison between the different variations of calculation

450

C-98
COCOSYS: Fire benchmark #2 case 1

*200 c - -

ATE

0 So 100 150 200 250 300 3E

Te s)

Fig. 3-8 Casel: Plume temperatures

Fire Benchmark #2 case 1

COCOSYS calculation

0 400 450

Fig. 3-9 Visualisation of the fire plume (temperature) in COCOSYS

C-99
Fire Benchmark #2 part 1

CFX calculation casel

Fig. 3-10 Visualisation of the fire plume (temperature) in CFX

COCOSYS: Fire benchmark #2 case 1

l | arx A in~Cocterface| CFX4terf ce

15- -- _.-._ .. *8._ exp

10 A ; t. -

0 so 100 ISO 200 250 300 350 400 450

time t(s)

Fig. 3-11 Casel: Interface height

C-100
COCOSYS: Fire benchmark #2 case1

LLL.

I 100- 

so ....... , .... . i

0 50 100 1S0 200 250 300 350 400 450

time t(s)

Fig. 3-12 Casel: Upper layer temperature

3.2 Case 2

Similar to case 1 COCOSYS simulates the temperatures quite well. The Fig. 3-13 to

Fig. 3-18 show the comparison between the calculation and the measurement for the 3

measurement trees. As for the case 1 the calculated temperature stratification is calculated somewhat to strong. A similar behavior is also found for the calculated plume

temperatures. Fig. 3-19 shows the different values of plume temperature for a calculation with a complete reaction of heptan over the pool surface (CO full) and the optimal

case with a 60% reaction efficiency. Because only the temperatures can be compared,

an additional consistency check is not possible (for example for CO2 concentration).

Fig. 3-20 presents the comparison of the heat loss to the wall structures for different

calculated variations. The red curve corresponds to the optimal COCOSYS case. In the

base calculation of COCOSYS (COCbase) the infiltration, heat transfer conditions are

set according the benchmark specification. The heat loss calculated in the CFX calculations is lower. This is a reason for the higher calculated temperatures too.

C-101
The mass flow rate through the infiltration depends strongly on the specified boundary

conditions. Fig. 3-21 presents the comparison between the three COCOSYS calculations. In the first calculation (COCfuOl all environmental control volumes are started

with a total pressure of 1.013 bar. Because the total pressure in the roof part of the fire

hall is smaller a convection loop in the wrong direction (from upper to the lower infiltration) starts. In the calculations COCbase and COCopt all mass flows are positive (from

inside to outside) during the heat up phase. Later at about 150s a convection loop in

the right direction starts. The differences between the red and green curves show the

effect of the moved upper infiltration to the top of the hall roof.

Fig. 3-22 and Fig. 3-23 show the average values for the interface height and upper

layer temperature. Also the correspondence between calculated and measured temperatures looks quite well, the calculated interface layer height is somewhat lower.

COCOSYS: Fire benchmark #2 case2

120 -

i) 100

PI4)

X 80- is

e

4)

e 60- 4)

P- 7

40 -

20 

_I

time t(s)

Fig. 3-13 Case2: Temperatures at the lower part of tree 1

C-102
COCOSYS: Fire benchmark #2 case2

120

U 100

E

I-

,- 60 a)

40

20

# I--r ----- 

* I II

n COC-Opt-OASZ YM

COC-opt_GAS_ZEP

COC-opt GASZ KP

° COC-optGASZOP

+ TI.8

* T1.9

V T1.10 

I 1 , I 

I .. . . .. .. . I . . .. .. I. . . .. .. . I .. . .. .. . .I ff --

0 50 100 150 200

tkne t(s5)

250 300 350 400

Fig. 3-14 Case2: Temperatures at the upper part of tree 1

COCOSYS: Fire benchmark#2 case2

. - CALGAS ZDE .

CAL GAS ZYA

120- CALGASZBJ -_-_ °CAL-GAS Z AL

A CALGAS-ZZM.''

U 100 T2.2 ------ r-------'---

V 80 - O T25 ------- 

60 ----------

0 50 100 150 200 250 300 350 400

time t(s)

Fig. 3-15 Case2: Temperatures at the lower part of tree 2

C-103
COCOSYS: Fire benchmark #2 case2

UIa

E

4)

ti

time t(s)

Fig. 3-16 Case2: Temperatures at the upper part of tree 2

COCOSYS: Fire benchmark #2 case2

140 -

120 -

U 100- I

4)

CL

E

4) 60

a)

40 -

20 -i

0-

I , , . , ,I

, , , , I I I .~ ~~~~~~~~~~~ n--- -- -- -- ---- ---- -------r----r

UCALASZTE

-CAL GAS-ZJUF , , , a I ,- -

° CAL GAS ZQL

A CAL GAS PN a , ,

| T3.1 , A T3.2 ~~~--------___ iZ__LE

T3.3 _ .O T3.4 ______

V T3.5

0 50 100 150 200 250

time t(s)

Fig. 3-17 Case2: Temperatures at the lower part of tree 3

300 350 400

C- 104
COCOSYS: Fire benchmark #2 case2

140 ---- _ -'--- - - -- - -- ----- r -- - - - - -'~--~ -n--~---

120 - ----- --- - ------ - ------

U 80o --_____---

6i 60-- ] r)|ty ,CAL_GASZ_2

40 - 50 100 150_._ 2 23 30

400 - --------- ------- T3.1

I I s T

~~~~~~~~~I I I 

w_ '' rL''''X' trrrl- '' ' I ' I IwTsrlrrr I a~ COCtG..U.s 

0 50 100 150 200 250 300

tirne t(s)

Fig. 3-18 Case2: Temperatures at the upper part of tree 3

COCOSYS: Fire benchmark #2 case2

400 

COCopt.GASZJJ *

-COCopt_GAS_ZUQ . .

COCtull_GAS_ZJJ I

COCtul_ GAS.ZUQ .. . .....

A TG2

a..

2~~G

1i 00 - ---- ------ --- ~ ---------- --- ----- --

0 50 100 150 200 250 30

time t(s)

Fig. 3-19 Case2: Temperatures inside the plume

350 400

30 350 400

C- 105
COCOSYS: Fire benchmark #2 case2

2000

0

'a

'U

0 50 100 150 200

time t(s)

Fig. 3-20 Case2: Heat flow to the wall structures

250 300 350 400

COCOSYS: Fire benchmark #2 case2

3

3- ~~~~~~~~~~~~~~~~~ -- - -- -- -; 

2- -----------------------r------- ------- ----- ~---~~r~~~~

.I I I I I I I I I I I I

I I I_ 1 -- I . I 

Ior;t v 7L *4 - E 1 - - -- - --' --- - - ' ---.- - ' - -- - -'- - ---- ----- - --------- '- -- -- - -- --- 

-3.. , .

x COCopt_LEAKVJ1

* COCoptLEAKEU1

A COCoptJLEAWOI

° COCcptLEAKEOI

+ COCaptLEAKTI

O COCbaseLEAKWU1

^ COCbaseLEAKEUI

M COCbaseLEAKVV1

* COCbeseLEAKEOI

COCftulljEAiOwu1

COCIUILLEAKEUI

COCIULCLEAKNO1

COClulLEAKEOI

0 50 100 150 200

tkme t(s)

250 300 350 400

Fig. 3-21 Case2: Calculated mass flow rates through the infiltrations

C-106
COCOSYS: Fire benchmark #2 case2

20

15

H \ ~~~ ~ ~ . ~ ~ .I ~I 

0 50 00 ISO 200 250 3

time t(s)

Fig. 3-22 Interface height in case 2

COCOSYS: Fire benchmark #2 case2

200*

COC-Tlow

ACOC-Tup

*exp

1S0 - exp ---- -... --------... J-------

so - I -- I -------- -------- I -- -I

U

3:

0 50 100 150 200 250 30

timet(s)

Fig. 3-23 Upper layer temperature in case 2

00 350 400

0 350 400

C-107
3.3 Case 3

Allthough the ventilation system has been used and the doors are open in case 3, the

behavior is very similar to case 1 and 2. Fig. 3-24 to Fig. 3-30 show the results of the

optimal COCOSYS calculation compared with the experimental measurements.

Fig. 3-31 presents the injected and burned mass of heptan. About 30% of the heptan

mass remains unburned. This value is compared to the value specified in the benchmark description relatively high.

COCOSYS: Fire benchmark #2 case3

140- . -r-------- r- -- -- ---r- -- -- --r- --- -- -- -Ir-- -- -- --r

a CALGASZCE

-CALGOAS ZXA I

120 - < CALGASZ AJ _---._ -- _ -- _----____- - -- -- - -- __ -- __ - ____ o CAL-GASZZK

A CALGAS_ZYM I

U 100 A T1.2 ----------- r-------

Ii 80- V T1.5__ '2

6 S-------- r------- -- r-------- r--- 

40 ---+ -' 

20 -~ ^ ---------- -------- r-------- r-------- r0 50 1 00 1 S0 200 250 300 350

time t(s)

Fig. 3-24 Case3: Temperatures at lower part of tree 1

C-108
COCOSYS: Fire benchmark #2 case3

y100- T ---

_ T1.9 0 __

e T.0 - - -- - - - -- - -

40 -- z _ L - -- -- -- -L- -- - ---- - - --

20- If t-------- ---~~~------------ --------

° 0

0 S0 100 150 200 250

time t(s)

Fig. 3-25 Case 3: Temperature at upper part of tree 1

COCOSYS: Fire benchmark #2 case3

140 ------- --- r-- -- r-------- r

UCALGASZDE

- CALGAS Z YA

100. ~ ~ I ~~~I II

120 x CALGAS_1eJ -, .L -- .

.

p 10 ------ T2 --- ---- r------------ r4 0 ------------- >>--r--S-:'----

0 

0

0 50 100 150 2-- 250

Fig. 3-26 Case 3: Temperature at lower part of tree 2

C-109
COCOSYS: Fire benchmark #2 case3

140- .-.- r-------r- --- -- -- - -- r--- -- -- -r- -- -- --- r- -- -- -- - CAL_OAS_ZZM 

CALGASZTP |||J 

120 CAL_GAS ZZP ----- __. --------- ___ _,_ 

* T2.S 

5.~~~T. 9 100 T2.'8 

" PT2.19; r -

60 - - fi;gg)f<r;f---r-----------------r------ ~r ~------

40 - C - - - L ------ -- -- ------- --- -- 0.

I I I I I

0 S0 100 150 200 250 300 3

timre t(s)

Fig. 3-27 Case 3: Temperature at upper part of tree 2

COCOSYS: Fire benchmark #2 case3

140 - I- 1--------r--------r-------- r--------r--------r- a CALGASZTE

120 - CALGASZKJ -- _ -- -- _- - -- -- - - -__ - I L -- -- _ _ - L -------- ___ ° CALGAS_Z_iL

A CALGASjPN

U 100 A T32 --- r-------- r-------- r-------- r--- -t~r- - + T3 3 r

oT3.4 80 - VTrs - - i- f 

E

s0 60 - -- -- -- -- r - f ~ -- ~ -- -- - -- - -------

20 20 -- -- - r--------T r--- --- r --- -- -r -------- r r-, 4, .r Ir 

0 S0 100 150 200 250 300 350

time t(s)

Fig. 3-28 Case 3: Temperature at lower part of tree 3

C-l10

S0
COCOSYS: Fire benchmark #2 case3

I,

9C

I

4

2

40-. l ~~~~-- r-- -- --- r-- - -- - -- -r- -- -- - -- r - :~~~~--- r a CAL_GASZPN s @ ,, _ _ _ *CALGASZR i I , S_ I > Ie 

CALGAS_3ZS L - . L..

100- T _ S I I I 

V TS.10 S I I , I

eo~~~~~~~~~~~- t-r ---------''f':0------- r-------- r-------- --------- 

O-.0 - -7 - ----- < r------ - - --- - --- - -- r -- - - --- r -- -- ----- r

0 50 100 150 200

time t(s)

250 300 350

Fig. 3-29 Case 3: Temperature at upper part of tree 3

COCOSYS: Fire benchmark #2 case3

U

I

E

a.

0 so 100 150 200 250 300 350

time t(s)

Fig. 3-30 Case 3: Plume temperatures

C-lll
COCOSYS: Fire benchmark #2 case3

30

25

20X --------- r-------- r-------- r---r- f

--------- --------- r -- -------

- I , I I 2

0 S0 1 00 1 50 200 2

time t(s)

Fig. 3-31 Case 3: Injected and burned heptan mass

COCOSYS: Fire benchmark #2 case3

20-

_ , * n CC£-Werfece

t0 exp

. l l O ~~~~~exp 1 5 -- _- _ ---.--- _ ____L_______ - - -- -- -

CD

0 so 100 150 200 250

time t(s)

Fig. 3-32 Case 3: Interface height

50 300 350

300 350

C-112
COCOSYS: Fire benchmark #2 case3

0 50 100 150 200 250 300 350

time t(s)

Fig. 3-33 Upper layer temperature

3.4 Comparison between the cases

Between the different experiments (casel to case 3) the experimental boundary conditions have been somewhat changed. From case 1 to 2 the surface of the pool have

been increased. And in case 3 the ventilation system has been used and the doors are

open. The calculated heat release rates (Fig. 3-34) and temperatures at T1.10 (Fig.

3-35) show a consistent behavior according to the modifications. The increasing of the

pool surface leads to an increased heat release rate and increased temperature. Starting the ventilation system (with open doors) lead to a further increase of heat release

rate and a reduced burning time. The difference between case 2 and case 3 is relatively small (compared to that between case 1 and 2) because in each case there are

oxygen rich conditions. An additional ventilation has only a minor effect in this case.

Although the temperatures are to high, the CFX code delivers consistent behavior too.

Fig. 3-36 presents the results of CFX and COCOSYS (COCfuII variation) in comparison with the experimental data.

C-113
COCOSYS: Fire benchmark #2

5000

4000

3000

a

a)

CDa 2000

1000

0

time t(s)

Fig. 3-34 Calculated heat release rates for the 3 cases

COCOSYS: Fire benchmark #2

a m ; ; ; , a - , ; 

140- .----- -- -- ar----- --------- -- - --- I

o COC-casel _GAS_Z OP I I

COC-case2_GAS ZOP , a

120 A. COCcase3_GASZOQP I--------- + T1.10 _ r '-° V 

* T1.10

U -V T1.1 IO

U is0600 -~ ------ f ------ ------ r---r~~-------

6 0 - -- - - - r - -im - - -t- - - - - - -I - - - - - -I - - - - - --r- - - - - --

Fi . 335 CmIso of th mesue an caclae tepraue a TI .1

20 - ~------- --- ~---r--~----------------------

°~~~~~~~~~~- 1, 1l 1 1l1l1 -- ---- ---- 1, ---- 1- - -1--

o S0 1 00 1 S0 200 250 300 350 400 450

time t(s)

Fig. 3-35 Comparison of the measured and calculated temperatures at T1.10

C-114
COCOSYS: Fire benchmark #2

250 -

I T1.10

' ' 4 ~~~~~~~~~T1.10

__-~~~~~~~ ~~~~g ~~~~~ ~COUfiiI-rAselGASZO 200- .-_ -- I __-r_- A, - COCcA.seGAS Z OP

_ J * -> > .* U.. COCfuI-case3_GAS_ZOP

&- 100~v 1 

_~~~~~~~~~ ; -0----gj-n -r - -: -f - -- - -- - - ---------.--- : -cae

10 - - -- -- - -$ --- - -- -~ - --- -- -- -

4? * , g 

s - -- -- - -- - -- -------------------------- 1-- I-- --- -- --1

0 50 100 150 20 250 300 350 40 450

time i(s)

Fig. 3-36 Comparison of CFX and COCOSYS for all cases

4 Conclusions - Next steps

COCOSYS show for the temperature good results in comparison with the experimental

data. The calculated temperature stratification in the hot gas layer is somewhat to high.

The missing plume model leads to some restriction for the calculated plume temperatures. It has to be pointed out, that the reaction efficiency has been adjusted to the experimental data. The resulting value of about 70 % burned heptan mass seems to be

somewhat low. Therefore it would be nice if some more experimental data would be

available (concentrations, temperature decrease after burning, velocities). Up to now,

COCOSYS has also no model to simulate the soot behavior.

The influence on temperature on different simulation of some boundary conditions

(heat transfer to walls, infiltration) leads to a temperature decrease of about 20 K. In

comparison to the effect of the efficiency factor this is rather low. One reason may be,

that there are oxygen rich conditions, why the differences between case 2 and case 3

are also very small.

C-115
The CFX results are delivering too high temperature, corresponding to the initial

COCOSYS calculations with complete burning of heptan. Concerning CFX the stability

has to be improved (especially for case 3), the infiltration has to be checked. It has already be found, that an reduction of the so-called eddy-break-up-factor would improve

the results.

For COCOSYS it is planned to use the detailed model, where the pyrolysis rate is calculated by the program. Therefore some additional initial data is necessary. The efficiency factor should be checked against other experiments.

C-116
Group Project 1

International Collaborative Project

to Evaluate

Fire Models

for Nuclear Power Plant

Applications

Nick Williams

Toby White

Scott Kelly

Performance Based Design FP 571

Professor J. Barnett

Spring 2002

C-117
Table of Contents

1. Introduction

2. Initial Assignment

3. Purpose of Benchmark Exercise #2

4. Objectives of Benchmark Exercise #2

5. Description of Benchmark Exercise #2

6. Expected Model Output Part 1

7. Expected Model Output Part 2

8. Key Issues

9. Part 1 Case 1

10. Group Background

11. JASMINE

12. Main Modeling Assumptions and Inputs

1. Materials

2. The Fire

3. Geometry

4. Preparing a grid

5. Radiation

6. Turbulence Model

7. Running the simulation

13. Results

14. Conclusion

Appendix 1 Part 1, Case 1 HRR vs Time curve

Appendix 2 JASMINE 3D representation of initial geometry

Appendix 3 JASMINE 3D representation of final geometry

Results Graphed

JASMINE 3D Temyerature Contour 2ranhs

C-118
FP 571 PERFORMANCE BASED DESIGN

SPRING 2002

GROUP PROJECT 1

1. Introduction:

The purpose of this project is to evaluate the ability of computer fire models to

predict fire growth in a large hall; such as the turbine hall in a nuclear power

plant. Fire protection engineers (FPE) are frequently asked to conduct fire safety

evaluations of buildings and structures. Following a performance based design

approach, FPE' s draw upon risk analysis in selecting the most probable fire

scenarios that may take place in the structure. These fire scenarios are then

scrutinized to predict heat transfer, room temperatures, and smoke movement.

This information allows the FPE to evaluate the performance of the structure

according to pre-established fire safety goals and objectives. Due the complexity

of fire and fire growth in a structure, FPE's are forced to make broad assumptions

in order to achieve useful results. Until recently, FPE's were limited to hand

calculations using numerical analysis techniques. Similar to most scientific fields,

computers have greatly enhanced the FPE's ability to take fire scenarios and

predict building performance. This report is part of a class assignment undertaken

by graduate FPE students at Worcester Polytechnic Institute. Our class results

will be forwarded as part of the International Collaborative Project to Evaluate

Fire Models for Nuclear Power Plant Applications. Our group was tasked with

using JASMINE, a computation fluid dynamics computer model described below,

to model Part 1, Case 1 of Benchmark Exercise #2. This report is written with the

general assumption that the reader is familiar with this international collaborative.

2. Initial Assignment:

Our initial class assignment is described below:

1. Identify key issues in Benchmark Exercise #2 as part of the International

Collaborative Project to Evaluate Fire Models for Nuclear Power Plant

Applications.

2. Describe model and associated challenges with using the model to

complete Benchmark Exercise #2.

3. Complete item 2 using Jasmine, a CFD model. First complete Part 1 of

the exercise and then attempt Part 2.

3.0 Purpose of Benchmark Exercise #2:

To challenge fire models in respect to issues associated with predicting the

effects of fire in a large volume.

C-119
1. Objectives of Benchmark Exercise #2:

1. To examine scenario(s) that will provide a harder test for zone

models, in particular with respect to fire spread in large volumes

representative of, say, a turbine hall.

2. If possible, to make use of experimental data to fulfill the

requirement of more thoroughly testing the predictive capability of both

zone and CFD fire models. Again, as noted in the exercise description, the

emphasis when selecting scenarios was on large smoke filling volumes.

1. Description of Benchmark Exercise #2:

1. Part 1 includes three cases based on full-scale experiments inside a

test hall using two Heptane fires of different diameter. Thermocouples

were used to record temperatures directly above the fire and at locations in

the test hall. Bi-directional probes were used to measure gas velocity in

the case with open doors. The geometry, material properties of walls and

ceilings, ambient conditions and ventilation conditions are provided in the

exercise. The following table is a summary of Part :

Case 1-Priority Case 2 Case 3

doors closed doors closed doors open (0.8 m x

no mech. Exhaust no mech. Exhaust 4m)

natural leakage natural leakage mech. Exhaust (11 m|

pool diameter = 1.1 7m pool diameter =1 .6m ignore natural leakage

pool diameter = 1.6m

C-120
2. Part 2 is an optional exercise. This part includes three cases inside a

rectangular building with dimensions similar to a real turbine hall. As part of our

assignment, we will model a two level building more representative of a turbine

hall. The geometry, material properties, and conditions are also provided. We

are also asked to include an open gated hatch in the floor/ceiling between levels.

For Part 2, we are asked to find the effect of the fire on cable targets inside the

hall. Since we will have two levels, we will model one cable target just under the

lower level ceiling, and model two cable targets near the roof as steel structural

members. The difference between the three cases in Part 2 is in the ventilation

for the hall.

2. Expected Model Output Part 1:

CFD

Temperatures at thermocouple trees

(T1. 1,...,T1.1 0,T2.1,...,T2.1 0,T3.1,...,T3.10)

Temperatures at plume thermocouples

(TG1.1 & TG.2)

Infiltration flow rate (cases 1 & 2)

Mass flow rate in/out door 1 (case 3)

Mass flow rate in/out door 2 (case 3)

Velocities at the two doorways (case3)

(V1.1,...,V1.3,V2.1,...,V2.3)

Total heat loss rate to solid boundaries

Heat loss through mech. Exhaust (case 3)

Interface height

(using reduction of thermocouple tree data)

Upper layer temperature

(using reduction of thermocouple tree data)

Total heat release rate

(within whole hall)

C-121
7.0 Expected Model Output Part 2:

1. Similar to Part 1, but different locations for the thermocouple trees. The gas

temperatures are to be provided at 1-meter intervals.

2. The gas temperature directly above the fire is requested at two locations (CFD

models), but now at heights 9 m and 19 m.

3. Three doorway velocities should again be considered at 0.5 m, 1 m and 3.5 m

height, on the vertical enter line of each opening.

4. The total heat loss through the doorway opening should be provided if possible.

5. Upper and lower layer oxygen concentration should be provided in the case of

zone models. For CFD models the oxygen concentration at the thermocouple tree

locations should be provided.

6. For each cable/steel structural member target, the following should be provided,

where possible, at each reported time:

1. maximum incident flux

2. maximum surface temperature

3. maximum enter-line temperature

1. Key Issues:

For the purpose of this assignment, we first defined key issues as one of the

following:

1. Expected model outputs

2. Main modeling assumptions and inputs (to be developed as the report

is completed.

3. Issues in need of clarification, or additional research.

4. Issues which will be difficult to model.

1. Using the model to produce the expected outputs of the exercise.

2. Assumptions for the heat release mechanism.

3. Assumptions for radiation treatment (if included, important issues may

include the treatment radiation transfer to solid surfaces, the

absorption/emission in the gas phase and radiation from soot plume.

4. The number of control volumes or elements.

5. Assumptions in turbulence model.

6. Modeling the two obstructions inside the hall (Part 1)

7. Modeling the air infiltration.

8. Accounting for the air movement with mechanical ventilation.

9. Effective selection of elements accounting for long computation times

associated with CFD model.

10. Choosing a combustion mechanism (stoichiometric ratio, mass bum rate).

11. Utilize the data from Table 3 (Fuel mass release rates) to model the fire.

12. Selecting nodes to compare to experimental data.

13. Modeling the cable/structural steel targets.

C-122
14. Reconstructing the model for case 2 (new geometry, added physical

features)

2. Part 1 Case 1:

Our second and final class assignment was to use the fire model provided

to our group to model Part 1 Case 1.

10.0 Group Background:

Based on the fact that this project is being completed both as a class

assignment and as a submittal as part of the aforementioned exercise, it is

appropriate to describe the group members for any particular reader of this report.

The group consists of three members who are all pursuing Master of Science

(M.S.) degrees in Fire Protection Engineering (FPE). Two group members are

senior Mechanical Engineering undergraduate majors who are pursuing the M.S.

FPE degree under a 5 year B.S./M.S. program. One group member has a

Bachelor of Science degree in Civil Engineering accomplished prior to the

introduction of Windows based computer programs. This is the second semester

in the FPE program for all group members. The first semester includes core

courses in Fire Dynamics, Building Firesafety, and Suppression courses. Prior to

this project, no group members had any Computational Fluid Dynamics (CFD)

experience or fire modeling experience with any fire modeling program. One

group member utilized extensive AUTOCAD experience to assist in using the fire

model.

11.0 JASMINE:

According the software manufacturer BRE, "JASMINE (Analysis of

Smoke Movement In Enclosures) uses the numerical technique of computational

fluid dynamics (CFD) to describe the heat and mass transfer processes associated

with the dispersion of combustion products from a fire. The processes of

convection, diffusion and entrainment are simulated by the Navier-Strokes

equations. JASMINE has been developed, validated and improved over a twenty

year period and includes the key processes of buoyancy, convection, entrainment,

turbulence, combustion, thermal radiation and boundary heat transfer relevant to

the movement of smoke."

In summary, JASMINE is a complex CFD fire modelling program that can

produce accurate results, when compared to other models, provided the program

users have extensive fire dynamics knowledge and fully understand the program.

JASMINE does come with several example sessions and a help manual.

However, our group found the fire and geometry in the example sessions to be

simplistic and did not assist in preparing the model to evaluate the fire and

geometry presented in this exercise. The help manual is thorough but more of a

dictionary listing of terms than something that can be used to troubleshoot some

C-123
of the problems we encountered. Most noteworthy were problems encountered

with creating a geometry which reflected the pitched roof and then creating a grid

for analysis. More details regarding these issues and the assumptions taken to

obtain results are included throughout this report.

12.1 Materials:

For the large hall structure considered in Benchmark #2, the walls and

ceilings are constructed of a .OOlm layer of sheet metal on the outside with a .05m

layer of mineral wool on the inside. The floor is constructed of concrete. The

two objects inside the building were treated as adiabatic concrete. Our first

attempt to model the walls and ceilings was to use a function provided by

JASMINE that allows the user to insert objects. Using this function the walls

were constructed of sheet metal and mineral wool was wrapped as individual

objects inside the entire structure. This process was very time consuming and

actually inhibited the program from producing results. JASMINE appears to

place permanent grid lines on all geometry lines; therefore, this produced too

many nodes within the wall materials for an analysis.

Our second attempt for selecting the materials was to create an equivalent

material using thermal circuit principles from heat transfer theories. However, as

our fire is the heat source, this is a transient heat transfer, and this does not allow

the materials to be simplified into one material using this principle.

Our final approach was to consider the relative thickness of the inner

mineral wool as compared to the thin sheet metal and to also consider the limited

conductivity of the mineral wool. Therefore, in our effort to continue with our

first attempt to achieve results for Case 1, Part 1, we decided to input only the

mineral wool as the wall material and make this material "thermally thin" or

isothermal in the model. This may not truly reflect the heat loss through the walls

and ceiling, but as mentioned earlier, it may eliminate some of our problems with

JASMINE placing too many grid nodes inside the walls.

12.2 The Fire:

The single fire source was constructed using equation 1 provided in

Benchmark Exercise #2:

The combustion efficiency was .8, the heat of combustion used was

44,600 kJ/kg, and the fuel mass release rate was taken from the data for Case 1 in

Table 3 of Benchmark Exercise #2. This data was placed into an Excel

spreadsheet and graphed for each given time in a scatter plot and curve fit to

represent the HRR curve that needed to be placed into JASMINE. The graph

showing our results is included as Appendix 1 of this report.

C-124
JASMINE utilizes various windows for inputs and allows the user to

select an option that will design the fire. The following is a copy of the

JASMINE fire originally used in our analysis:

The fire in Part 1 Case 1 is a circular Heptane fire with a 1.17 m diameter.

Since JASMINE, as shown above, only models the fire with X & Y dimensions,

an equivalent area was calculated to allow for a square fire of equivalent area.

Any data difference in the model values from the experiment due to this

equivalent area should be nominal based on the size the test hall. JASMINE

allowed us to select Heptane as the fuel. In order to match the HRR curve

extracted from the exercise data, our JASMINE fire was modeled in three phases.

The first phase or growth phase was modeled as an ultrafast t squared fire. The

function was modified to provide a growth that is similar to the experimental fire.

The second phase was modeled as steady state with a time period that closely

matches the steady period shown in Appendix 1. The last phase was a decay

phase using the JASMINE default value for the decaying phase of the fire. The

time for the end of the fire also matches the data provided.

12.3 Geometry:

All group members spent extensive time trying to model the geometry of

the large hall in JASMINE. The pitched roof provided a challenge since all

angles for compartments modeled in JASMINE are right angles. The roof was

created by placing block objects into a rectangle room with incremental steps to

represent the pitched roof. Although this increases the surface area available for

heat transfer, it allows for a more accurate prediction of smoke movement.

Appendix 2 of this report shows the modeled test hall for Case 1 with the vents

included to represent natural leakage. The duct for the mechanical exhaust

C-125
system is not included in the space based on the assumption that this small

amount of material in a large test hall would not greatly affect our model results.

Although this created a room which was similar to the test hall, we found

this geometry to be too complex to achieve results. In order to create a slope

similar to the diagonally pitched roof, many steps were placed into the space.

This presented great problems when taking the next step to prepare the CFD grid.

JASMINE creates permanent grid lines matching the geometry created by the

user. Therefore, each individual step along the roof became a node for the model

to evaluate. The spacing was less than 50 mm which seemed to prevent

JASMINE from conducting any analysis.

In order to obtain results for Case 1 our group calculated an equivalent

volume rectangular piped to prevent further problems with the grid. Using

calculations for an equivalent volume, the height of the hall became 15.84 meters

while the other dimensions remained the same. Our group recognized that this

changes the predicted the smoke movement, and presents a different surface area

for heat transfer. Our modeled upper layer will develop at a different rate due to

this geometry change. Four vents were placed in the locations prescribed in the

exercise to represent the natural leakage that would actually take place. A picture

of this geometry is provided in Appendix 3.

12.4 Preparing a Grid:

This aspect of the modeling was the most demanding aspect of the

exercise for our group. A large pare of our difficulty is most likely due to our

overall lack of CFD experience. Our group was provided two versions of

JASMINE, one limited to 5,000 elements, and one not limited. Since the CFD

computation is time comprehensive, the number of elements needs to be smartly

managed to obtain results in a reasonable time. Our intention was to limit the

initial selection of control volumes by preparing a grid that only concentrated on

placing elements near and above the fire and near the vents. This would provide a

shorter initial analysis and allow our group to examine results and make

adjustments. However, as noted in our 'geometry' section (12.3) above,

significant problems were encountered when JASMIME placed grid lines

coincident with all geometry lines. Since our step period was so small to

duplicate the pitched roof, elements were spaced too close for analysis. The

original grid was over 450,000 nodes.

Using our final geometry, the grid spacing was manipulated manually to

place more control volumes in areas that required more accuracy. These areas

including near and above the fire and near the vents in the walls. This grid

placement focuses the computer model on these areas and smartly limits our

nodes to reduce computation time. Our final grid was 117,000 nodes.

C-126
12.5 Radiation

JASMINE allows the user to select none, near node, six flux, and a DT

method. Our group selected a six flux radiation model. Our fire is modeled using

the total heat release rate (HRR). Selecting six flux for radiation allowed for

JASMINE to account for the radiation emitted and absorbed from the 4 walls, the

ceiling, and floor. The materials values were taken as .95 as prescribed in the

exercise. The two objects were treated as adiabatic. Modeling radiation in this

manner increases the computational time for the model, but should yield more

accurate results.

12.6 Turbulence model

JASMINE has options available for the selection of turbulence. Our group

selected the Eddy breakup combustion default selection recommended by the

JASMINE users manual for most problems. In selecting Eddy breakup,

turbulence model is automatically selected as K-Epsilon to appropriately model

the gas flow supporting combustion. The heat transfer for function for the wall

was the general default function in JASMINE.

12.7 Running the Simulation:

Our original intention was to run the model with the simplified geometry

and the ones elected material and then attempt to run further simulations with the

original stepped roof geometry with one selected material. If the simulation was

successful, this would tell us that our original modeling of the sheet metal and

mineral wool together as "thermally thick" or with transient conduction was the

source of error. However, our first simulation took over 80 hours to complete

only 400 seconds of the intended 800 second fire simulation. Therefore, our

results are based on one simulation with geometry and material noted above. Due

to computer speed and capacity, data was saved every 40 seconds. In obtaining

400 seconds of data, we were able to reach the decay or third phase of our

modeled fire which began at approximately 360 seconds.

1. Results:

Each data set was saved over 40 second intervals to save computing time

and space. Again, our group found retrieving specific results from JASMINE

difficult at first and time-consuming. We were to find data for specific points on

the thermocouple trees used in the experiment. However, our results in

JASMINE are presented according to each node in the grid spacing. Therefore,

we had to match the node spacing with the thermocouple spacing the retrieve the

desired results. The results obtained are reasonable considered our inputs and

assumptions. For graphed results, see here.

C-127
Thermocouple Temueratures

The following table shows thermocouple temperatures provided in the

format requested in the exercise:

Time (s) T. )T.2() T1.3 C) T1.4 (C) T1.5 C

0C) ~ T. C *T. C T1.2 CC) IT TT. C 17,. 0

0.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0

40.0 20.0 20.0 20.0 20.0 20.0 200 20.0 20.0

80.0 20.8 20.4 20.4 I20.9 22.9 24.8 26.8 31.7

120.0 21.6 21.6 21.6 23.4 36.1 40.1 42.6 43.2

160.0 22.6 24.0 35.8 41.3 44.5 46.2 47.4 46.9

200.0 26.6 29.8 40.6 46.4 51.3 54.7 57.4 58.0

240.0 30.0 .34.6 43.0 51.4 58.4 629 66.1 6.

280.0 34.2 38.6 45.5 57.4 65.1 69.6 72.8 70.0

320.0 37.2 41.6 52.2 62.6 70.1 74.6 77.7 73.6

360.0 40.3 45.6 572 66.5 74.0 78.4 81.3 76.3

40.0 42.7 50.7 606 69.4 76.6 808 83.7 77.3

Time (5 T2.1 CC) IT2.2 C) T2.3 (C) T2.4 CC) T2.5 (C) T2.6 CI T2.7 (C)C T2.8 (cQi

0.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0

400 020.0 20.0 20.0 20.0 20.0 20.0 20.0

80.0 20.6 20.4 20.3 20.4 21.5 23.9 29.0 373

120.0 21.6 21.6 21.5 22.5 35.4 40.5 45.6 47.7

160.0 22.8 25.2 34.0 40.8 44.5 47.0 50.1 53.7

200.0 27.4 29.9 40.2 45.4 50.6 550 61.1 6.

240.0 30.0 35.4 41.9 50.4 5763.70042

280.0 .34.4 38.8 t;42.8 56.9 64.6 70.1 76.9 80.0

320.0 37.4 42.0 49.7 62.0 69.6 75.2 81.7 84.0

360.0 40.4 45.6 53.7 66.2 73.6 79.0 85.4 87.0

400.0 .42.1 j47.0 160.5 68.9 76.1 81.4 87.4 85.9

Time s T3.1 C) T3.2 (C) T3.3 C) T3.4 (C) T3.5 (C) ThJC T. C T3.8 ec)

0. 0.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0

40.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0 20.0

80.0 21.0 20.6 20.4 20.4 209 24.4 32.6 5.

120.0 22.3 22.3 22.4 23.8 34.0 40.3 '46.9 55.5

160.0 23.4 24.9 31.9 39.8 44.5 47.5 53.4 69.3

200.0 27.5 31.4 39.1 43.9 49.1 54.4 63.6 87.5

240.0 30.6 37.0 40.2 48.9 56.4 62.8 7296.

280.0 34.8 40.0 42.3 55.7 63.4 69.8 79.5 102.6

320.0 38.1 43.3 47.3 61.8 68.7 747 4.5 ~j 107.3

360.0 39.7 46.7 53.6 65.7 72.5 78.5 88.0 =111.5

400.0 41.2 .49.4 [I59.5 68.3 74.9 80.9 89.1 96.5

The last thermocouple (#8) is at the roof height 15.84m.

C-12 8
Infiltration Flow Rate

The following table shows the infiltration flow rate through the vents:

VELOCITY S LOWER VENT EAST WALL VELOCITY OLOWER WEST WALL

Lower Upper Lower ^ Upper

Vent Middle Vent Vent Middle of Vent

Time (a) Edge of Vent Edge _ Edge v Vent Edge

0.0 0.00 0.00 00. _ 0.00 0.00 0.00

40.0 L ; 0.00 . -0.68 F -0.83 i 8.33E-02 0.53 0.52

80.0 . -0.19 -0.81 -0.40 5.53E-02 - 1.06 0.96

120.0 -0.21 -0.81 -0.42 __ 4.25E-02 - 1.06 1.01

160.0 _ -0.11 -0.40 -0.21 _ -6.85E-03 - 0.54 0.51

200.0 _ 1.87E-02 4.34E-02 -1.02E-03 i -2.25E-02 - -6.90E-02 -1.66E-02

240.0 0.13 0.43 - 0.20 e -7.80E-02 -0.34 -0.12

280.0 9.06E-02 0.74 0.56 _ ^ -0.12 0.50 0.20

320.0 - 5.07E-02 0.97 0.86 ___ -0.16 -0.68 -0.29

360.0 7.50E-02 1.21 1.15 ___ -0.20 -0.85 .' -0.37

400.0 0.15 2.29 A 2.25 _ -0.37 -1.58 1 -0.71

(The node alignment in our model only allowed data to

upper vents)

Velocity @ Middle of East and West Wall

Upper Vents

be collected for the middle of the

EAST WALL WEST WALL

Time(s) | (m/s) V(m/s)

0.0 - 0.00 0.00

40.0 0.71 0.75

80.0 _ 1.54 I 1.62

120.0 2.08 2.11

160.0 2.24 2.31

200.0 2.58 2.70

240.0 2.90 3.03

280.0 3.10 3.24

320.0 3.22 3.37

360.0 3.25 3.42

400.0 2.03 2.17

Variation in velocity reflects are movement affected by the two objects in the space.

Interface Height

In order to extract an interface height, we used two different methods.

The first method was to simply use the 3D contour visual aids provided by

JASMINE (see pictures) to see the change in temperature in the test hall. We were then

able to change temperature contours to represent a two layer 3D picture. Placing the grid

spacing over this contour picture we were able to find the interface height. This became

C-129
more difficult as the mixing of temperature layers increased as the time period increased.

The following table shows the interface height (in terms of distance from the floor):

_ Layereight.m) Layer height (m)

Time sir (NIST)

0.0 15.84

40.0 15.84

80.0 13 12.06

120.0 10.8 8.6

160.0 7.'-98X 0 4.89

200.0 6.84 4.81

240.0 54 3.36

280.0 3 2.76

320.0 3 .j , 1.53

360.0 i 2.0 1.09

400.0 1.0 .24

(Contour means first method, NIST means second method below)

The second method was drawn form the Journal of Research of the National

Institute of Standards and Technology, "Data for Room Fire Model Comparisons,"

(Peacock, Davis, & Babrauskas, 96,4,1991). This paper describes a method to" take a

limited number of point-wise measurements to determine a layer interface and

temperature."

Here are the steps taken to obtain data using this method:

1. Temperature data for all three thermocouple trees was averaged at each

thermocouple height (as suggested in the Benchmark Exercise)

2. As described by Peacock, Davis & Babrauskas, the equivalent two layer

zone height is the height where the data temperature equals Tn,

where . In this equation, Cn is a coefficient,

normally .2, Th is the temperature at the bottom of the room. Tax is the

maximum temperature.

3. Also described by Peacock, Davis, & Babrauskas, the interface height is

calculated by iterating between data points to find the interface height at

Tn.

4. The upper layer temperature is the average temperature from all three

thermocouple trees above the interface height.

C-130
Thermocouples above fire

The temperature at two thermocouples above the fire:

Time (s) TG. CC) _TG.2 CC)

0.0 20.0 20.0

40.0 122 21.0

80.0 573 136

120.0 218 85

160.0 385 123

200.0 496 - 174

240.0 681 188

280.0 641 192

320.0 656 197

360.0 670 _ 208

400.0 a 1 3 118

The upper layer temperature:

Again, we used both JASMINE 3D contours and the NIST method described

above. _

Upper Layer ¢Upper Layer

T:emperatu r ::Temperature

Time (s) Contour ) ( f'iS

0.0 

40.0 --

80.0 2 31.5

120.0 40.5 39.2

160.0 42.5i 4 43.1

200.0 47 50.9

240.0 X 56.6 53.8

280.0 5 58.8

320.0 63.2~ 63.1

360.0 _ 66.9 66.6

400.0 _ 68.8 68

The total heat release within the whole hall is 513.2 MJ.

1. Conclusion:

As participants in this international exercise, we do not have access to the

measured results from the experiment to compare our modeled results. Therefore,

we cannot comment on how comparing our model results with the experimental

data.

However, our results appear to be reasonable and comparable to other

groups within our class. More importantly we have proven that computer fire

model results cannot be taken at face value as hard and fact predictions for

C-131
building evaluation or design. CFD models are powerful tools and a complex

model such as JASMINE can be used to provide more accurate results then most

computer simulations. However, a tool such as this can be dangerous. Basic

knowledge of fire dynamics and fire protection engineering may allow a user to

obtain results from these models that may not be accurate or worse, not

conservative. In order to achieve results that can be used in building evaluation

and design, the user needs extensive fire dynamics and fire protection engineering

experience couple with total understanding of CFD and the computer model at

hand. Our experience in this exercise highlights the need for great caution when

making fire protection decisions based on fire model simulations.

C-132
Appendix 1 Part 1, Case 1 HRR vs Time curve

C-133
Appendix 2 JASMINE 3D representation of initial geometry

C-134
Appendix 3 JASMINE 3D representation of final geometry

C-135
FP 571: Performance Based Design Lars Sorthe

Benchmark Exercise #2: Fire in a Large Hall Jim Shannon

February 25, 2002 Garrett Kaye

Introduction:

As part of the curriculum for Professor Barnett's Performance Based

Design course (FP571, Spring 2002), our class is participating in the International

Collaborative Project to Evaluate Fire Models for Nuclear Power Plant

Applications. Specifically, we are dealing with Benchmark Exercise #2, which is

entitled "Fire in a Large Hall". Our class of nine students was divided into three

separate groups, and each group was assigned a different computer model to

evaluate the scenario described later in this paper. It is important to note that we

were told to ignore the fact that the hall is actually a nuclear power plant facility,

and simply model the space as a large hall. This is because as fire protection

engineering students, our main concern is to determine how accurately fire

models can represent fires in a large space, rather than dealing with any

additional nuclear power related complexities.

Casel:

Large Hall

Dimensions: 27 m x 13.8 m x 19 m .4

Pitched roof -i _ 

Two large obstructions on floor

Fire source located 16m from west

wall and 7.4 m from south wall

Heptane pool fire with a diameter of

1.17 m

Figure1: Picture of modeled space

C-137
The Fire Model:

Our class looked at a total of three (3) computer fire models: two

computational fluid dynamics (CFD) models, and one zone model. The CFD

models we looked at are called Fire Dynamics Simulator (FDS) and Jasmine,

respectively, while the zone model is called CFast. Our group was assigned the

FDS model.

FDS is a CFD model of fire-driven fluid flow, developed by the National

Institute of Standards and Technology (NIST). FDS software numerically solves

a form of the Navier-Stokes equations, and is appropriate for low-speed,

thermally driven flow with an emphasis on the smoke and heat transport from

fires. The first version of FDS was released in February 2000, while the second

version was released recently in December 2001. Both versions of FDS are

written in Fortran.

The Combustion Model:

Our group chose to use the second version of FDS for Benchmark

Exercise #2 because of the improvements that were made since the first version

was released. The first version of FDS contains a relatively simple combustion

model that utilizes "thermal elements". Thermal elements are "massless"

particles convected with a flow and heat release at a specified rate. According to

the user manual', this model is easy to implement and relatively cheap

computationally; however, it lacks the necessary physics to accommodate under

ventilated fires.

The second version of FDS is more comprehensive, and handles oxygen

consumption more naturally by solving an equation for a conserved scalar

quantity, known as the "mixture fraction". The mixture fraction is defined as the

fraction of gas at a given point in the flow field that originated as fuel. The model

assumes that combustion is mixing-controlled, and that the reaction of fuel and

oxygen happens infinitely fast (i.e. instantaneously). The mass fractions of all the

major reactants and products can be derived from the mixture fraction by means

C-138
of "state relations", which are empirical expressions solved by a combination of

simplified analysis and measurement.'

FDS is based on a set of complex equations that describe the transport of

mass, momentum, and energy resulting from fire-induced flows. However, the

actual forms of the equations that FDS uses have been simplified to reduce the

calculation time required. The technical user manual 2 says that this simplification

of equations is justified because the general equations of fluid dynamics describe

a rich variety of physical processes, many of which have nothing to do with fires.

As a result of this simplification, FDS models scenarios as quasi-steady, where

the characteristics of each cell (such as gas temperature and velocity) are

uniform throughout the cell at any given time. The accuracy with which the

actual fire dynamics can be simulated therefore depends on the number of cells

that can be incorporated into the simulation, which is ultimately limited by the

performance of the computer used to run the simulation. Given the processing

speed and memory of today's computers, simulations are typically limited to less

than one million cells. In real life, combustion processes take place at scales of 1

mm or less, while the scales associated with building fires are on the order of

meters to 1 O's of meters. Therefore, in order to simulate all relevant fire

processes, the range of scales for length that need to be accounted for is roughly

104 to 105. The lesson to be learned from all of this is that FDS cell size and

distribution could have a significant impact on the accuracy of results.

C-139
FDS Input:

The FDS input file is a text file with the file extension `*.data'. In the input file,

the name of the output files need to be specified. If this detail is forgotten, earlier

output files with the same case name will be overwritten and the data will be lost.

The input file determines the characteristics of the fire scenario through written

Fortran code. Listed are some of the inputs for this exercise, however this is not

a complete list of all the variables that can be specified:

* Time limit for the run

* Global parameters

* Describing the fire,

* Physical dimensions (x, y and z),

* Cell distributions (x, y and z),

* Obstructions

* Boundary conditions

* Vents

* Detectors and thermocouples

* Output files

In addition to the input file there is a database file that gives the user the ability to

specify thermal properties for different materials. There are several default

properties given-by NIST that the user can utilize.

The input file is written by the user and is the only way for the user to

affect how FDS will do calculations. Since the user must write the input in code,

this gives an unnecessary dependence between the results and the user's

knowledge of FDS and Fortran code.

Benchmark Exercise No. 2, Case 1:

As mentioned previously, case 1 is a small fire with only natural ventilation.

C-140
The Fire:

In the handout, the fire is described using mass loss rates at given times

during the fire. Using this data with the heat of combustion (AH:) for heptane, a

heat release rate for the fire is easily created. Furthermore this gives us the

possibility to specify a heat release rate per unit area. Since this is a pool fire, it

is reasonable to assume the fire to grow instantaneous after ignition and no

growth time normally associated with t

2 fires.

Heat Release Rate

2,000

1,500 

1,000 

0

0 60 120 180 240 300 360 420 480

Time [sec]

C-141
The decay period of the fire can be specified using FDS by inputting when

a decline occurs in the hear release rate at a certain time in the simulation. This

requires more understanding on Fortran code which is beyond the knowledge of

our group, so we only ran the simulation for 300 seconds.

With a fire area of 1 .09m2, the heat release rate per unit area can easily

calculated which gives the following graphical presentation.

Heat Release Rate Per Unit Area

1,800 _

1,600 1,200 --Atle

.1,00

800

IL 600

400

200 -

0

0 60 120 180 240 300 360 420 480

Time [sec)

C-142
Physical Dimensions and Cell Grid:

FDS allows the user to specify the physical dimensions and number of

cells associated with each direction. Unless otherwise instructed, FDS will

distribute the cells normally over each dimension. A Poisson solver based on

Fast Fourier Transforms in the calculations also limits the number of cells in each

direction. The dimensions of the grid should be of the form 2m3n5I, where m, n

and I are integers. A good example of how this works is the number 72, which

can be written as: 2333; however numbers like 51, 73, and 109 cannot be

specified.

Since all surfaces must line up with the grid, no objects or other physical

shapes can be circular or diagonal. In this exercise the roof is diagonal, and the

fire and mechanical vent is circular. For those shapes, an equivalent area must

be found that will simulate the same shapes.

i_ .: _ . 1 . n xi#

R.. . __,Z"

_ Ex ====_, in d=_=n 

==== _::: : = 0 __-- = ,___ 

~0ti 1 3--fb "| |_-

Fiur 2:Exm l fri in -irecin

FDS gives the user the option to concentrate cells around areas of interest

which helps minimize the number of cells used. This in turn reduces the

computational time of the scenario. This option is described later in the sensitivity

study.

C-143
Fire, Objects and Vents

The fire is located 1 m above the floor near the center of the room and

there are two large rectangular objects on the floor in the hall. The surfaces of

these two obstructions were modeled as concrete, with properties specified in the

handout. This is fairly easy incorporated in the input file. All objects in the hall

must be given specific x, y and z values describing where they are located

(xl,x2, yl,y2, zl,z2). If the dimensions do not line up with the grid, FDS will

move them to the closest grid. This is because all calculations are done from cell

to cell and there can not be anything dividing a cell.

When modeling the roof geometry, there is a trade off between surface

area and volume since there cannot be any diagonal lines. Instead we had to

make the roof with only vertical and horizontal lines thus making it look like steps.

This will impact the flow near the roof, but FDS2 does have a solution to this

problem. To lessen the impact from these steps, a parameter must be written into

each surface line in the input file. According to the user manual', this is not a

perfect solution to the problem, but it does lessen the impact from velocities

around sharp corners.

Surfaces

As mentioned earlier, the obstructions inside the hall are simulated as

concrete blocks. The floor is also concrete, while the walls and the roof is a

combination of sheet metal and mineral wool. According to the user manual',

FDS has the capability to simulate sheet metal over an insulated surface.

However, while trying this option, the program would not start and gave an error

for the surface. Even with the default sheet metal in the database file given by

NIST, the same error occurred. Describing a surface as only mineral wool was

possible, but to see if there were any significant differences in the results, several

runs with different surfaces were done. Details regarding this are discussed later

in the report.

A solid surfaces affected by convective or radiative heat transfer from the

surrounding gasses can be specified as either thermally-thin or thermally-thick.

C-144
Specifying the thermal properties of the surface in the database file does this. For

thermally-thin surfaces, a product of the specific heat, density and the thickness

of the layer are specified. A thermally-thin layer can further be specified as

insulated so no heat is lost to the backing material. Thermally-thick surfaces are

specified through the thermal diffusivity, the thermal conductivity and the

thickness of the material. Setting these parameters will direct the code to perform

a one-dimensional heat transfer calculation across the thickness of the material.

In neither case does the heat get transferred through the entire wall into the next

room, but for this case it doesn't matter since we are only modeling one room.

Runs

As a part of the sensitivity study, several runs were completed. The differences in

these runs were:

o Number of cells

o Cell distribution

o Surfaces

o Heat release rate

Casela Casei b Caseic Caseld Casele*

HRRPUA 1700 kW m-2 1700 kW m 2 1700 kW m-2 1500 kW m-2 1700 kW m-2

Surfaces Concrete and ~Concrete and Concrete and Concrete and Surfaces mineral wool All concrete mineral wool mineral wool insulated seet

_______________ ~~~~metal

x- 27m/1 08 x- 27m/1 08 x- 27m/1 08 x- 27m/1 08 x- 27m/1 08 Pdim./ cells y- 13.8m/30 y- 13.8m/30 y- 13.8/56 y- 13.8m/30 y- 13.8m/30

z- 19m/75 z- 19m/75 z-19m/75 z- 19m/75 z- 19mf75

Cell distribution Transformed in Transformed in Normal Transformed in Transformed in

the y-dir. the y- dir. the y-dir. the y dir.

* Casel e did not work

We used Casel a as the base run, while the other runs where done to see if the

changes had any significant impact on the results. Case1 e was supposed to be

the base run, but since this case did not give any results we had to choose

another one.

C-145
Sensitivity Study:

Surface, for the different surfaces the difference in 'All concrete' and the

'Concrete and mineral wool' runs showed some difference in the heat of the

smoke layer. The difference was not significant, but in the order of about 10%

lower for the temperature rating of the thermocouples. The change in the

thermal values for the surfaces are of the wall might give different values for the

hole run, so to be conservative the higher temperature will give more severe

results.

The grid size and grid spacing is of more interest. The runs with denser

cells around the fire had fewer cells than the runs with a normal distribution of

cells. There could not be found any change, less than 5% in the temperature

ratings, but the number of tracer-particles fell drastically with normal distribution.

This is expected from the fact that the fire will happen in an area of fewer cells

and this will have an effect in how the fire will 'burn' in the model. The details

regarding this is outside the knowledge of the members of the group, but as long

the runs with fewer, but denser cells around the fire, give somewhat same results

we can assume that this error is within the expected range.

Changing the fire size give lower themperature reading of the thermocouples, as expected. The model is reacting to the change in the heat release

input, so the model is not doing anything unexpected here.

Results

Finding the smoke layer is not easily determined with a CFD model. The

visual output in 'Smokeview' show the tracer particles as the model runs. From

these visual readings, it is shown that the smoke layer is not descending below 4

C-146
meters, which is the height of the smaller object in the space.

Figure 3: Smoke layer interface at 300s

In the handout, a method is described using the temperatures given by the

thermocouples. This method uses a one-dimensional analysis utilizing upper and

lower temperatures and conservation of mass.

H

(H - int up + zil.= I T(z)dz =1,

0

(H- zt )up + Z T= I dz =I2

which can be rewritten as

T, II I2 - H2) 7i =T1. H) t +I2TW - 2TkWH

Where Tow is the temperature at the lowest discrete measurement location

(TN.1) and 11 and 12 are calculated from the discrete data set using a quadrature

rule, e.g. Simpson's Rule. Tup is then calculated by applying the mean value

theorem over the integral Z=Zint to z=H

C-147
TP T1 _ 1 T(z)dz H - zit, ZZ

Mass Flow Rates

For Casel there was only natural leakage. In order to simulate this, four

openings to the exterior were placed on the east and west walls. The location

and size of the vents were specified in the handout.

FDS2 uses thermocouples to measure different quantities. So a

thermocouple can measure temperature and velocities as well as other

characteristics. Locating thermocouples near the vent openings and measuring

the velocities at those openings found the mass flow rates. The mass flow rate

can then be found by assuming a uniform velocity throughout the opening.

Where positive direction is into the enclosure.

Location Velocity Density Area Mass flow rate

[m/sec] [m3/kg] [M2] [kg/sec]

West, bottom 1.7 1.20 0.5 1.0

West, top -2.6 1.07 0.5 -1.4

East, bottom 1.7 1.20 0.5 1.0

East, top -2.6 1.07 0.5 -1.4

Total heat loss can be measured, but only as a visual presentation through

Smokeview. The technical way of showing this is found in the Smokeview user

manual, but it must be specified in the input data file. The heat loss is shown as

a change in the color on the surfaces. This feature takes a lot of computational

time and was only done in the base run. The smoke view file and the associated

files take a lot of computer storage space and will be made available on a CD.

Another way of measuring heat loss to the walls is to place thermocouples along

that are, but the uncertainty in the location and number of thermocouples needed

were outside the limits of this group.

c-148
The upper layer temperature was found with the thermocouples in the building. A

total of three (3) thermocouple trees were located in the space. The temperature

measuring of these trees are presented below in charts.

Thermocouple Tree 1

0 

- TI A

TI.1O

aa

0 180 300

Time [s]

C-149
Thermocouple Tree 2

120

100

80

h..q

45

1w

0

a.

I--

60

40

20

0

0 60 120 180 240 300

Time [s]

C-150
Thermocouple Tree 3

- aT

}0~~~~~~~~~~~~~~~~~~~~~~~~~~~T

AK~~~~~~~~~~~~~~~~~~~~~~~3

T3'

60 120 180 240 300

Time [si

C-151

0
Plume Thermocouples

120-

100-

80 -

- TO

- TO

40

20

0 60 120 180 240

Time sJ

300

C-152
Heat Release Rate

>

-Handout

- FDS

-FDS Trendline

0 60 120 180 240 300

Ticm [s1

C-153
Reference:

1. Fire Dynemics Simulator (Version 2) - User's Guide, Kevin B. McGrattan

et al, NIST, November, 2001

2. Fire Dynamics Simulator. (Version 2) - Technical Reference Guide, Kevin

B. McGrattan et al, NIST, November, 2001

3. Handout regarding Benchmark 2 exercise

C-154
Analysis of Benchmark Exercise Two:

An Examination of Large Turbine Hall Fires with the CFAST Fire

Modeling Code

Westinghouse Safety Management Solutions LLC

A. R. Martin and D. A. Coutts

amber.martin@ wxsms.com

allan.coutts @wxsms.com

The Savannah River Site (SRS) has an obligation to fulfill Department of Energy (DOE)

expectationsf1 2]. The DOE expectation is that software quality assurance (SQA) is in place that

will ensure that computer software will perform its intended functions in a consistent manner and

that software modifications will not result in unanticipated problems. SRS is in the process of

improving the site SQA program.

The SQA program is currently being applied to CFAST, Version 3.1.6. In the process, code

capabilities and limitations are being evaluated. A typical problem requiring analysis at SRS is

evaluating heat transfer to a liquid filled process tank and estimating evaporation from the tank.

An understanding of how to accomplish this using the output available from CFAST is required.

In addition, several sample problems must be established that provide input and output so that,

when the code is initially installed, it can be demonstrated that the installation was successful.

As part of the SQA effort, Benchmark Exercise 1 (Part 1) was developed into a sample problem

format and work is in progress on Benchmark Exercise 2 (Part 1) for use as an additional sample

problem. Under this present effort, preliminary evaluation of Benchmark Exercise 2 (Part 1) has

been completed for cases 1, 2 and 3. Since CFAST is limited to a rectangular geometry, the

ceiling height was adjusted to 15.84 m to maintain the turbine hall volume. A lower oxygen

limit of 12%, as used in Benchmark Exercise 1, a radiative fraction of 20% and a relative

humidity of 50% were used. For the wall layers, the specification stated sheet metal on top of

mineral wool. A three layer material with mineral wool (5 cm thick) between two layers of sheet

metal (each layer 1 mm thick) was created. Pyrolysis rates and ventilation conditions are as

identified in the specification for part one of Benchmark Exercise 2.

In conclusion, SRS is charged with verifying and validating the CFAST software.

Demonstration of code capabilities and limitations as well as establishment of sample problems

has been accomplished by exercising benchmark problems 1 and 2. In addition, a non-fire

mechanical ventilation flow case has been established.

IImplementation Guide for use witi DOE Orders 420.1 and 440.1 Fire Safety Program. G-420.1/B-0 G-440.1/E-0.

September 30, 1995.

2 Quality Assurance for Safety-Related Software at Department of Energy Defense Nuclear Facilities.

DNFSB/TECH-25. January 2000.

C-155
Large Eddy Simulations of Fire Tests in a Large Hall

Kevin McGrattan and Jason Floyd

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, Maryland 20899

USA

In cooperation with the fire protection engineering community, a numerical fire model, Fire Dynamics Simulator (FDS), is being developed at NIST to study fire behavior and to evaluate the

performance of fire protection systems in buildings. Version 2 of FDS was publicly released in

December 2001 [1, 2]. The model is based on the low Mach number form of the Navier-Stokes

equations and uses a large eddy simulation (LES) technique to represent unresolved, sub-grid

scale motion. The fire is modeled by solving a transport equation for the conserved scalar quantity

known as the mixture fraction, a linear combination of the fuel and oxygen that indicates the mass

fraction of the gas originating as fuel. The advantage of the mixture fraction approach is that all

of the species transport equations are combined into one, reducing the computational cost. Thermal radiation is modeled by solving the radiative transport equation for a non-scattering gray gas

using what is known as the Finite Volume Method [3]. Using approximately 100 angles, the finite

volume solver requires about 15% of the total CPU time of a calculation, a modest cost given the

complexity of radiation heat transfer.

FDS has recently been applied to a series of benchmark fire tests performed as part of the "International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant Applications." The

tests analyzed here make up Benchmark Exercise #2. Three fire tests were performed in a large

fire test hall. In each, a pool of heptane was burned for about 5 minutes, during which time gas

temperatures were measured in three vertical arrays and at two points within the fire plume. The

fire size and ventilation configurations were changed from test to test. Details of the tests can be

found in these same proceedings.

The heat release rate of the fires in each case was calculated from the measured mass loss rate

of fuel, thus the model is not making a prediction of the total energy output. While it is possible

to predict the fraction of the total energy output that is emitted from the fire as thermal radiation,

we chose to apply an empirical fraction of 35 % based on numerous experiments. The purpose

of the numerical model in this exercise is to predict how the energy from the fire is transported

throughout the test hall as a function of time. The key to handling this problem properly is to

simulate well the mixing of hot combustion products and fresh air within the fire plume. The

technique adopted by FDS for this purpose, Large Eddy Simulation (LES), is not widely used in

the fire community because of the extensive development of various Reynolds-Averaged NavierStokes (RANS) models, some of which are demonstrated within these proceedings. The benefit of

LES over RANS is that it renders a more faithful representation of the fire and plume dynamics

because it captures fluid motion at length and time scales consistent with the underlying numerical

grid. For example, animations of the fire and smoke plume show the pulsating and oscillating

behavior observed in actual experiments. With the RANS approach, this motion is filtered out and

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the fire and plume are rendered as time-averages of the actual flow fields. While both approaches

have been demonstrated to work in a variety of fire applications, we believe that that LES approach

will eventually be adopted more widely because of its more faithful rendering of fire behavior.

Of course, the outcome of an LES calculation is only as good as the underlying numerical grid. If

the governing equations of motion are approximated on a numerical grid whose cells are too large

relative to the characteristic length scales of the fire or fire plume, not only will the realistic fluid

dynamics be lost, but the mixing will be under-estimated, and in the case here, the upper layer

temperatures predicted by the model will be hotter than those measured. For this reason, up to

now the LES technique has not been considered of practical use to the fire protection engineer.

What has made the technique useful is faster, cheaper computers and better numerical methods.

A recent advancement for FDS has been the implementation of multiblock gridding, that is, the

use of more than one structured numerical grid in a single simulation. Until recently, EDS used a

single uniformly-spaced rectangular mesh to divide up a largely rectangular space into hundreds

of thousands or millions of cells. The benefit is ease-of-use, the downside is that it is difficult

to adequately resolve the numerical grid in regions of interest, like the fire plume, when a large

space is to be modeled. Preliminary calculations of the benchmark fire tests required on the order

of 80 CPU hours on a 1.7 Ghz Pentium IV processor. By using more than one numerical grid,

the CPU time was reduced to 20 hours, and the resolution in the region of the fire and plume was

improved.

The figures in the accompanying presentation show the geometry of the test hall and the layout of

the various numerical grids used in the simulation. The finest grid surrounding the fire is 4 m by

4 m by 10 m high, with grid cells 13 cm on a side. Five other separate grids are used to cover

the rest of the space at a resolution of 40 cm. Within each grid, the cells are uniform in size. In

all, 216,000 grid cells are used in the calculation. Ten minutes of real time are simulated. Some

simplifications to the geometry include making the burner and the exhaust duct square rather than

round, and approximating the sloped ceiling as a series of stair steps. Otherwise, everything else

is as specified in the problem description. Heptane (C7H1 6) is used as a fuel. Temperature and

velocity predictions are recorded at all of the specified locations.

The results of the three calculations agree well with the measurements. For Test 1, the predicted

temperatures at the 5 upper thermocouple locations in each array are within 10 'C of the measured

temperatures, usually on the high side. The lower 5 temperature locations show good agreement as

well, with the greatest difference being for the lowest two thermocouples, which under-predict the

measured temperatures by roughly 10 C. Given slightly higher temperatures in the upper layer,

it is not surprising to see slightly lower temperatures somewhere else since the model is energy

conserving. The model assumes that there is no air movement in the hall except for that induced

by the fire or the ventilation system, thus one would expect for the level of mixing to be slightly

under-predicted. The prediction of the temperature at the lower thermocouple location in the fire

plume is about 100 'C higher than the measurement. The prediction at the higher location is about

10 "C higher.

For Test 2, the agreement between model and experiment is better than in Test 1. The reason

for this is that the predicted and measured temperatures within the plume are within 10 C of

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one another. The simulations of Tests and 2 were conducted with the exact same gridding and

assumptions. The reason for the better agreement in Test 2 stems from the better agreement in the

plume itself. In general, for a given level of grid refinement, a larger fire is easier to model than a

smaller one, as in this instance. Another explanation of disagreement in plume temperatures is that

often in large scale fire tests air movements within the test space throw the fire plume slightly off of

its natural centerline, in which case numerical predictions are often high. In any case, in all three

tests, the agreement between model and experiment at the upper plume thermocouple location is

within 10 C meaning that the gases filling the hot upper layer are within a very close range to the

actual gas temperatures.

When these calculations were first attempted with a single numerical grid spanning the entire hall

with cells between 20 and 30 cm in size, the temperatures in the upper layer were over-predicted.

The difference in predicted and measured temperatures was reduced as the grid cells in the region of

the fire were reduced in size. This effect is made obvious by looking at animations of temperature

contour plots through a vertical centerline plane. When the grid cells are too large to resolve the

eddies that entrain fresh air into the plume, the hot gases are not diluted as much in the simulation

as in reality, and upper layer temperatures tend to be over-predicted. As in many studies we

have performed in the past on fire plumes, we find that very good agreement with experiment is

achieved when the fire is spanned by roughly 6 to 8 grid cells. Of course more is better, but this

level of resolution has been found to produce very good results at a modest computational cost.

Research continues to reduce computational effort by means of the multiple grids employed here,

plus parallel processing of the different grids.

[1] K.B. McGrattan, H.R. Baum, R.G. Rehm, G.P. Forney, J.E. Floyd, and S. Hostikka. Fire

Dynamics Simulator (Version 2), Technical Reference Guide. Technical Report NISTIR 6783,

National Institute of Standards and Technology, Gaithersburg, Maryland, November 2001.

[2] K.B. McGrattan, G.P. Forney, JE. Floyd, and S. Hostikka. Fire Dynamics Simulator (Version 2), User's Guide. Technical Report NISTIR 6784, National Institute of Standards and

Technology, Gaithersburg, Maryland, November 2001.

[3] S. Hostikka, H.R. Baum, and K.B. McGrattan. Large Eddy Simulations of the Cone Calorimeter. In Proceedings of US Section Meeting of the Combustion Institute, Oakland, California,

March 2001.

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5 th meeting of the International Collaborative Fire Model Project

Preliminary Results for Benchmark Exercise # 2 using CFAST and JASMINE

Stewart Miles, Fire and Risk Engineering Centre, BRE, UK

Part I of Benchmark Exercise # 2 is based on a series of fire experiments, performed in the

VTT test hall in Finland between 1998 and 1999 as part of the ECSC Steel Research

Programme. Each test involved a heptane pool fire one meter above the floor, lasting

approximately six minutes. The instrumentation included thermocouple readings at three

vertical columns, extending from the floor to the ceiling, and at various locations within the fire

plume. These readings provide the main measurements against which numerical predictions

are being compared for the current benchmark exercise. The measured temperatures have

been processed to give estimates of upper layer temperature and layer height, where it is

here assumed that a two-layer representation holds, and these are being used in the

comparison against zone model predictions.

The benchmark specification document [1] contains full details of the test hall and the three

cases being modelled. This was released in conjunction with a summary of the measurement

data against which to compare predictions.

For case 1 and 2 there was no mechanical exhaust and the doorway openings to the hall

were closed. However, the building is not airtight, and so the effect of air infiltration must be

modelled somehow. The suggested approach [1] is to include four small openings, each of

area 0.5 m2, two at ground level and two at a height of 12 m. For case 3 there was

mechanical extraction at 11 m3S through a duct 12 m above the floor, and for this case the

two doors were each opened to an area of 3.2 M2. An additional complication is provided by

the sloping cross-sectional shape of the ceiling, providing a further challenge to zone models

in particular.

This extended summary describes briefly some simulations undertaken by the author and the

findings drawn from them, and accompanies the presentation slides. Simulations of all three

cases have been performed with a zone model (CFASTIFAST version 3.1.6) and a CFD

model (JASMINE version 3.1.2). A sensitivity analysis has been undertaken for a number of

parameters, including the thermal properties of the walls and ceiling, the size and location of

the restricted ventilation openings (cases 1 & 2) and the 'equivalent ceiling height' in the

CFAST simulations. A CFD mesh sensitivity analysis has been conducted also.

All CFAST simulations have been performed with a single compartment with one or two

horizontal flow vents to the outside, and for case 3 an additional vertical HVAC vent to the

outside. The ceiling has been approximated as being flat, and for the majority of simulations

was located at a height of 15.84 m, which gives the same enclosure volume as inside the

actual test hall. The sensitivity to the choice of ceiling height has been investigated by

performing simulations with the ceiling at 13 m and 18 m. The fire source for each case has

been defined in terms of the specified time-dependent pyrolysis rate and a heat of combustion

of 44.6 x 1 O6 J kg-1. Furthermore, the radiative fraction was set to 0.2. For the 'baseline'

simulations the walls and ceiling were defined as conducting boundaries consisting of sheet

steel on top of mineral wool, with thermal properties and thicknesses as specified in the

problem definition. The sensitivity to the choice of thermal boundary condition at the walls and

ceiling has been investigated by using sheet metal only, mineral wool only and nonconducting (adiabatic) boundaries.

A further parameter that has been investigated in the CFAST simulations for cases 1 and 2 is

the size and location of the restricted ventilation wall openings for the 'infiltration' process.

Here the four original 0.5 m2 openings have been replaced by four 0.01 m2 openings in one

simulation and by two large openings of 16 m2 (at floor level only) in another. The effect of

increasing and decreasing the height above ground of the upper openings in the original

specification has been investigated also. Note that in the CFAST simulations, where there are

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two vents at the same distance from the floor they are combined into a single opening (with

an area equal to the sum of that for the individual openings).

JASMINE simulations of all three cases have been performed. The geometry of the test hall

was modelled as accurately as possible with a Cartesian mesh, with the result that the sloping

sections of the ceiling were approximated by a staggered (staircase) boundary. This gives the

correct volume within the ceiling space, but will have some influence on the heat and

momentum transfer at these sections of the ceiling. JASMINE models the Reynolds Averaged

Navier Stokes (RANS) equations of fluid motion, and employs a K-e turbulence model to

represent the effect of the turbulent motions on the flow field. Time-dependent simulations

were performed using a one-second time-step and the fuel pyrolysis rate given in benchmark

specification. An eddy break-up combustion model was employed, using a single step

reaction mechanism for heptane and an effective heat of combustion of 0.8 x 44.6 x 10 6 J kg-

'. Radiation transfer was calculated using a six-flux model, combined with an emissive power

model to calculate the radiation exchange from C02 and H20 combustion products.

Convection and radiation heat transfer to the solid boundaries was included. Conduction into

the boundaries was calculated approximately using the concept of a time-dependent

conduction depth into a semi-infinite material. Furthermore, the steel sheet was ignored in

these calculations, so that the conduction losses will in general have been under-estimated.

However, the conductivity of the solid was increased for some simulations to investigate the

effect of increased conduction losses on the gas temperatures and smoke layer height.

The ventilation openings have been modelled exactly as specified. However, additional

simulations have been performed for case 1 with narrow slot openings instead of the square

ones (but with the area of each maintained at 0.5 M2), and with partially porous east and west

walls, where the porosity was set to give an equivalent flow area as the vents.

A numerical mesh containing approximately 130,000 elements was used in most of the

simulations. A mesh refinement study was performed for two simulations, where the first 60

seconds was repeated using a mesh containing eight times as many elements, i.e. the

resolution was increased by a factor of two in each direction.

The preliminary results from the CFAST and JASMINE simulations are reasonably

encouraging and informative. Comparison plots of predicted and measured temperatures and

layer depths are shown in the presentation slides. The effect of varying conduction losses,

ventilation opening sizes etc are illustrated too.

Probably the most important finding, demonstrated by both the zone and CFD models, is the

sensitivity of the gas temperatures to the conduction losses to the walls and ceiling. In the

CFAST simulations the closest agreement with measurement was obtained by using either a

sheet metal and mineral wool two-layer material or by using the sheet metal alone. In the

JASMINE simulations the effect of ignoring the steel was apparent, with closer agreement

with measurement obtained when the conduction losses were then increased. The results so

far seem to indicate that the conduction into the steel is important. The smoke layer height,

however, seems to be less sensitive to the boundary conduction loss calculation.

An important issue in the use of the zone model is the choice of 'equivalent ceiling height'.

The sensitivity analysis performed so far indicates that while the upper layer temperature is

sensitive to the choice of ceiling height, the layer height is sensitive only during the initial

stage of the fire.

Both the zone model and CFD simulations indicate that the exact choice of openings in cases

1 & 2, to represent the infiltration process, is not critical. The only exception to this finding was

in the CFD simulation with porous walls, which indicated a break down of stratification after

about three minutes. However, the physical significance of implementing slightly porous walls

in a CFD simulation is somewhat uncertain and this result should be treated with caution at

this stage. The CFAST simulation with the very small openings produced high pressures

inside the enclosure, at a level that would have been greater than anything achieved in the

experiments. This supports the assumption that the building is not particularly airtight.

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Reasonable agreement has been shown between measured plume temperatures and those

predicted in the JASMINE simulations. The mesh refinement study has indicated some

sensitivity to this parameter, with the finer mesh producing results closer to those measured.

Further JASMINE simulations are currently being performed to investigate the mesh

resolution and boundary conduction issues in more depth.

CFAST and JASMINE simulations will be performed for Part II of Benchmark Exercise # 2.

This is a 'hypothetical' example for which there are no experimental measurements. However,

the dimensions of the building are greater than in Part I, and have been selected to more

closely represent a turbine hall. Full details of the geometry and cases to be modelled are

provided in the specification document [1]. The fire source is representative of a large

hydrocarbon pool fire. 'Target' cables and beams are included, for which the likelihood of

thermal damage is to be estimated. Although the building geometry is rectangular, in some of

scenario cases there is the added complexity of an internal ceiling, effectively dividing the

space into two connected compartments.

1. Specification for Benchmark Exercise # 2 - Fire in a Large Hall, February 2002.

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DETECTOR RESPONSE MODELING

Doug Beller, PE

NFPA International

1.0 INTRODUCTION

The purpose of this paper is to present information regarding current fire detector response

modeling. Fire detector response modeling in this paper refers to heat detectors, including

sprinkler links. While smoke detectors can be modeled using current heat detection models, this

is not highly recommended due to the magnitude of the uncertainties associated with the

predictions.

It is hoped that this brief paper will provide sufficient information regarding heat detector

modeling such that decisions can made regarding their applicability in nuclear power plants

(NPP). If it is decided that the current model is insufficient for such applications, then this paper

should provide enough information upon which to base a decision regarding future work.

2.0 DISCUSSION

2.1 Detector Modeling

The overall [smoke] detection process has been organized into five categories; property

generation, bulk property transport, local property transport, sensor modulation, and alarm

condition. [6] The first three categories are required by all detection models: the fire generates

the hazard to be detected; the plume transports the hazard conditions to the ceiling; the ceiling jet

transports the hazard condition to the point in space of interest. The final two categories are

detector specific: "sensor modulation" can be thought of as modeling how the sensor "knows"

what conditions are present; "alarm condition" is essentially the set point of the detector. In the

case of a sprinkler or heat detector, sensor modulation models the heat transfer to the sensing

device and the alarm condition is either a temperature (range) or a rate of temperature rise.

2.2 DETACT-QS

Currently, DETACT-QS is the only heat detector model that is publicly available. Other fire

models may also be used to predict detector activation; however, this is not necessarily their only

purpose.

2.2.1 Intent

DETACT was developed to calculate the response time of ceiling mounted heat

detectors/sprinklers and smoke detectors, installed under large unobstructed ceilings, for fires

with user defined, time dependent heat release rate curves [1]. DETACT is based on quasisteady ceiling jet assumptions [2,3]. The thermally activated device must be located under the

ceiling and within the ceiling jet.

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2.2.2 Assumptions and Limitations

1) The detector is ceiling mounted and located at the points of maximum temperature and

velocity within the ceiling jet below a ceiling [2]. The detector must be within 6% of the

ceiling height from the ceiling [4].

2) The ceiling is unconfined, unobstructed, smooth, flat, and horizontal. The model does

not account for hot gas layer effects due to walls or obstructions. The minimum wall to

wall distance is 2 to 4 ceiling heights. Vertical obstructions are required to be less than

1 % of the ceiling height for the ceiling to be considered smooth [2].

3) Only convective heat transfer is considered between the ceiling jet and the thermal

detector; no conductive or radiative heat transfer is considered. The detector is treated as

a lumped mass model [5]. The lumped mass model assumes that the thermal gradients

are neglected within the thermal element.

4) Smoke detector activation is assumed at a ceiling temperature increase of 13'C [1].

(Although this is a gross over-simplification of the phenomenon, it is an all too

commonly used assumption.)

5) Within the plume impingement area, temperature (r/H < 0.18: r = radial distance between

plume centerline and detector; H = height of ceiling above the fuel) and velocities (r/H <

0.15) are uniform an assumed to be the maximum values in the plume [2].

6) The fuel package and the plume are assumed to be in an unobstructed vertical axis. No

ventilation or stratification effects are considered. The heat release rate or the fire needs

to be sufficiently large so that the plume can be assumed to be vertical and axisymmetric

[2].

7) No transport time (or lag time) is considered for the hot gases to travel from the fuel to

the detector [2]. Therefore, increases in heat release rate will effect the temperature and

velocity of the ceiling jet immediately.

8) For each heat release rate input interval, the heat release rate is averaged over the interval

and assumed constant. Fire heat release rate should not double in less than one minute

[2].

9) Detector must be spot type [4].

2.3 SFPE Computer Model Evaluation Task Group Report

2.3.1 Intent

The draft report of the SFPE task group [4] states as its purpose: "This evaluation report provides

information on the technical features, theoretical basis, assumptions, limitations, sensitivities and

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guidance on the use of DETACT. This evaluation is based on comparing predictions from

DETACT with results from full-scale fire experiments conducted in compartments with ceiling

heights ranging from 2.44 m to 12.2 m and peak fire heat release rates ranging from 150 kW to

lOMW."

The type of evaluation that DETACT was subjected to is classified in ASTM E-1355 [7] as a

"specified calculation." In the specified calculation, the model user is provided with a complete

detailed description of model inputs, including geometry, test conditions, and the heat release

rate history of the fire [7].

2.3.2 Conclusions

Actuation temperature is the most sensitive input parameter; i.e., for a given percentage change

in the value of actuation temperature used by DETACT, it predicted a larger percentage change

in the output parameter(s) of interest.

When slow t-squared fires are used, the predicted actuation time will greatly increase due to the

relatively slow development of the fire. Very small source fires, especially smoldering, fall

outside the bounds of the analysis and are unlikely to be accurately predicted, either for ceiling

jet temperatures or detector actuation, by DETACT [4].

"Based on the comparison to predictions with measured values:

* As the ceiling height increased from 3.0 m to 12.2 m, the agreement between the

predictions and the data improved. The lower ceiling heights are more sensitive to

uncertainties in the experiment.

* There was better agreement between devices with higher RTIs (response time index) than

with devices with lower RTIs.

* The compartment evaluation scenarios demonstrate that DETACT should not be used in

situations where the limitations/assumptions of the model cannot be met, since the model

cannot be used with any reasonable expectation of reliability. For example, the use of

DETACT would not be appropriate in small areas where a gas layer would develop prior

to activation." [4]

2.4 Proposed Tasks

2.4.1 Scenarios to be Modeled

The first task is to define those scenarios requiring the prediction of fire detector activation. The

scenario definition should include a geometrical description of the room of fire origin (turbine

hall, control room, etc.) and specify the fire that may be experienced in that space. Presumably,

the type of heat detector and its description is a "given" for each NPP.

2.4.2 Scenario Differences

The scenarios described in 2.4.1 are next compared to the limitations presented in 2.2.2. Any

inconsistencies are to be noted for the following step.

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2.4.3 Questions

The series of questions below (in no particular order) is intended to facilitate the discussion:

1) Do the limitations shown in 2.2.2 preclude using DETACT in NPP?

2) Are the identified NPP scenarios sufficiently similar to those used in the development of

DETACT (see 2.2.2) to justify further work?

3) If they are not sufficiently similar is it still worthwhile to investigate using DETACT in

NPP scenarios? For example, since there is no other detector model available, are we

"forced" to use it?

4) Is there a "best" way to use DETACT in NPP? Some of the choices for "best" include:

* as is (i.e., no changes)

* modify program based on available data

* develop post-processor adjustment factors (may require using CFD models to

generate ceiling jet temperature and velocity profiles and develop correlations

based on the results)

* develop a new DETACT for NPP (i.e., extract property generation, bulk property

transport, and lumped mass models from DETACT and couple those to NPPspecific ceiling jet temperature and velocity correlations)

5) Is ceiling jet temperature and velocity experimental data available for the scenarios of

interest?

2.4.4 Benchmark Exercise

If there is sufficient interest in pursuing detection modeling in NPP the questions posed in 2.4.3

must be addressed first. Assuming that the decision is to proceed, some sort of benchmark

exercise will be needed. In order to undertake such an exercise experimental data sets depicting

the scenarios of interest must be readily available. The number of data sets needed will depend

on the nature of the exercise.

The nature of the exercise will depend on the answer to Question 4 of 2.4.3. If the decision is

made to compare DETACT prediction to experimental data and develop post-processor

adjustment factors, then a relatively small number of data sets is required (probably three to

four). If the decision is made to use the DETACT lumped mass model as the "sensor

modulation" and "alarm condition", and the "property generation" and "bulk property transport"

portions of DETACT along with a NPP specific ceiling jet correlation, then more data sets will

be required: at least six. The idea here is that three data sets could be used to develop the NPP

specific ceiling jet correlations, and the other three could be used to benchmark the resulting

model.

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It may be advantageous to use ASTM 1355 [7] as guidelines for this benchmarking exercise.

Several types of model evaluations are presented: blind calculation (basic description of scenario

provided); specified calculation (detailed description of model inputs provided); and open

calculation (most complete information provided, including experimental or other benchmarking

data). Using ASTM 1355 would provide some structure and formality to the exercise.

3.0 SUMMARY

The limitations imposed on the use of DETACT will most likely preclude its widespread use in

NPP. However, assuming that there is a need for detector modeling in NPP, the question then

becomes one of deciding what is the best (most expedient, most defensible...) course to meet this

need.

Presumably, four of the five components necessary for NPP detector modeling are present in the

current version of DETACT-QS. The DETACT component which needs either replacement or

augmenting is that describing "local property transport." In order to address NPP specific local

property transport, post-processing adjustment factors or a new component must be developed

for DETACT.

4.0 REFERENCES

1) Evans, D.D and Stroup, D. W., Methods to Calculate the Response Time of Heat and Smoke

Detectors Installed Below Large Unobstructed Ceilings, NBSIR 8503167, Building and Fire

Research Laboratory, U.S. Department of Commerce, Gaithersburg, MD, 1985.

2) Alpert, R.L., "Calculation of Response Time of Ceiling -Mounted Fire Detectors," Fire

Technology, 9, 1972.

3) Alpert, R.L., Turbulent Ceiling-Jet Induced by Large-Scale Fires," Combustion Science and

Technology, 11, 1975, pp. 197-213.

4) Evaluation of the Computer Fire Model DETACT-QS, August 2000 draft report, Society of

Fire Protection Engineers, Bethesda, MD, 2000.

5) Heskestad, G. and Smith, F.H., Investigation of a New Sprinkler Sensitivity Approval Test:

The Plunge Test, FMRC 22485, Factory Mutual Research Corp., Norwood , MA, December,

1976.

6) lerardi, J.A. and Barnett, J.R., "A Methodology for Predicting Smoke Detector Response",

Proceedings 4th International Conference on Performance-Based Codes and Fire Safety Design

Methods, Society of Fire Protection Engineers, Bethesda, MD, 2002.

7) ASTM E1355-97 Standard Guide for Evaluating the Predictive Capability of Deterministic

Fire Models, American Society for Testing and Materials, 1997.

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International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

A NEW MODEL FOR TIME LAG OF SMOKE DETECTORS

0. Keski-Rahkonen

VT Building and Transport, P.O. Box 1803, FIN-02044 VEr, Finland

Tel. +358 9 456 4810, Fax +358 9 456 4815, e-mail: Olavi.Keski-Rahkonen@vtt.fi

ABSTRACT

For smoldering fires existing time lag theories and observations of

smoke detectors are reviewed shortly and shown to be unsatisfactory.

The author showed earlier by that fluid dynamic phenomena cannot

explain in an acceptable manner the observed controversy. Using

general theory of filtering a model is proposed for time lag, where

small smoke particles partially separate from the carrier fluid while

penetrating into the smoke detector. At small flow velocities the

separation seems so effective that detection time is delayed much or

smoke may remain undetected totally. Since only scattered direct

experiments are available for comparison, and no resources for own

measurements were avialable at this phase, the model is presented for

fire science community to be tested and evaluated.

INTRODUCTION

Earliest possible detection of fires has been the goal of active fire prevention through

ages by any possible means. Since the introduction of numerical room fire simulation

codes there has been detailed tools to predict conditions and times for fire detector

response. Majority of these tools treat phenomena outside the detector. The long

chain from the incipient fire to detector has been modelled at different degrees of

sophistication starting from experimental plume models combined with zone type

room fire models and ending with various kinds field model simulations. At the

moment large eddy simulation (LES) techniques (McGrattan et al. 1998) to

determine smoke properties at detector location presents possibly the heaviest end of

the calculation tools available for the problem (Cleary at al. 1999, Farouk et al.

2001).

Despite that there are links not yet modelled to the same degree of accuracy as LES

simulation treats smoke transport and coagulation; one of these is smoke penetration

into the detector. A smoke detector has partially permeable walls separating the gas

volume in the detector from the volume around it. Walls of commercial detectors

consist mostly of mesh, or perforated plates. In each form they delay fire detection as

compared to a fully open detector. Heskestad (1977) modelled coupling of conditions

inside the detactor to outside conditions based on scaling principles. Since then

practically all modelling of smoke penetration into detectors has based on his work.

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International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

TIME LAG THEORIES AND DATA

Heskestad (1977) drafted a theory using dimensional analysis arguments for the time

lag At of a products-of-combustion fire detector

At= 1/v (1)

where is the mean convective flow velocity around the point detector, the

characteristic length scale, and y a non-dimensional coefficient characteristic for the

geometry. According to Heskestad Equation (1) is valid presuming 'viscosity effects

are not considered important'.

Bukowski (1975) as well as Johnson and Brown (1986) observed large delays of fire

detection for artificial cold smoke or smoldering smoke in a real size room although

the behaviour was neither quantified nor fully systematic. Brozovsky's (1991)

measurements showed, that the simple relationship predicted by Equation (1) did not

hold for low ceiling jet velocities. In Figure 1 his observations (dots) are plotted as a

function of velocity . Thin solid lines represent exponential fits by Brozovsky

(1991) on his limited set of data; his exponential fit at low values ( < 0.13 nits) is a

plausible approximation. Unfortunatelly, he did not extend measurements to speeds

exceeding 0.2 m/s. Therefore, it is very uncertain, what the behaviour would be at

higher velocities. Thus the curve crossing the point (0.4 m/s; I s) is only an

extrapolation without experimental confirmation beyond 0.2 m/s. No single set of

data was available covering the whole interesting region of velocities. More recently

Qualey at al. (2001ab) observed long detection times for low velocity ceiling jets as

a result of smoldering fires. Unfortunatelly they did not measure ceiling jet velocities

at detector location or other relevant data to allow quantitative comparison.

1000

100 177

10

1

0 0.1 0.2 0.3 0.4 0.5

Velocity (m/s)

Figure 1. Entry lag time dependence on flow velocity past a detector. Dots

(experimental data, Brozovsky 1991). (1) and (2): The delay time according to

Equation (1) as explained in text. (3): Fit according to Equation (2), critical velocity

To = 0.075 m/s). (4) and (5): Calculated models (Keski-Rahkonen 2001) explained

in text.

C-172
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

EXPERIMENTAL DATA REDUCTION FOR FIRE MODEL VALIDATION

Due to power law dependence on velocity an ad hoc modification of Equation (1)

was attempted (Keski-Rahkonen 2001)

At = ;r /(0 - FO ) (2)

This fit seemed plausible as shown in by line 3 in Figure 1. Since Brozovsky's data

cover only a rather limited range, Equation (2) is only one of the many possible fits

on the data set. Fits of Equation (2) on another data set (Cleary et al. 2000) is shown

in Figure 2. Again, plausible fits were obtained for the delay times. P1 was an optical

detector (. = 0.01 ms) and 1 ionizing detector (0 = 0.02 nm/s). Unfortunatelly,

experimental errors seem still to be rather high.

1000

Brozorsky|

100

1

0 0.1 0.2 0.3 0.4 0.5.

Velocity (m/s)

Figure 2. Detector time lag as a function of ceiling jet velocity according to

experimental observations (dots: Brozovsky 1991, squares: II by Cleary et al., 2000

diamonds: PI by Cleary et al. 2000). Full lines arbitraryfits on data using Equation

(2).

These examples show, critical flow velocity exists, but is hard to explain. The

behaviour described by Equation (2) seems to indicate, if the the fluid is taken as a

continuum, the flow has non-newtonian character plugging at velocities lower than

Vi. Qualitativelly, such a flow occurs, if the fluid, which here is actually an aerosol,

behaves collectivelly like a non-newtonian continuum fluid of Bingham plastic

(Irvine and Capobianchi, 1998). The analytical theories of such fluids would in

principle allow calculation of the flow in and out of the detector (Kawase and MooYoung 1992, Patel and Ingham 1994). However, there seemed not to be available

experimental data of rheological properties of smoke, which could settle this

question. The tacit assumption has always been smoke, like air, behaves as an almost

perfect newtonian fluid. Looking smoke as an aerosol and rejecting one phase

approximation seemed to shed new light on the problem, and to make non-newtonian

flow both unlikely and unnecessary as is shown below. The method is fully described

by Keski-Rahkonen (2002), and is shortly depicted here.

C-173
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

THEORY ON FILTRATION MECHANISMS

In a filter, like in a dense mesh, particles deviate from streamlines due to several

mechanisms. That property has been used for particle size separation for long (Fuchs

et al. 1962, Sinclair et al. 1979), but it is still a subject of intense studies (Lee et al.

1990, Sasse et al. 1994). Particles may collide with the wires on the mesh and stick

on them. The main mechanisms of deposition are diffusion, inertial impaction,

interception and gravitational settling. In the first approximation efficiences due

these factors add linearly when estimating total efficiency of filtration.

Approximating the filtering element by a cylindrical body, simple partial differential

equations can be derived for the aerosol concentration in laminar flow region (Cheng

1993). For derivation of the equation it is assumed: (1) The concentration is in a

steady-state condition; (2) the flow field in the device is a fully developed laminar

flow; (3) the effect of diffusion in the direction of flow is neclected; (4) no

production or reaction of aerosol occures in the device; and (5) the sticking

coefficient of the particle is 100% on the collection surface.

Penetration P of aerosol through these devices can be expressed in a power series of

exponential functions in the form

P = a. exp(-f3m) (3)

,3=1

where a is a numerical expansion coefficient, A an eigenvalue of the differential

equation describing particle diffusion, and m nondimensional argument of the

driving mechanism. Since the eigenvalues A, grow fast with n, for real devices a few

lower terms in the expansion of Equation (3) yields sufficent accuracy.

For diffusion batteries, used here as a model for a wire screen, Cheng and Yeh

(1980), and Yeh at al. (1982) derived an equation

m = A0 Pe 213 +AIR 2 + A2 Pe"112 R2 13 (4)

The pressure drop zAp through the screen is (Yamada et al. 1988)

16tcahu 327a u (5)

4P' = A 2 K d( df d f 

FLOW THROUGH THE SCREEN

To estimate the flow of smoke through the detector the problem is divided into two

formally different modes: flow of air, and flow of smoke particles. The detector is

idealized to a hemisphere surrounded by an insect screen. From air flow in the outer

field modelled using potential flow the continuity equation in steady state form

yields the pressure inside the detector pi. Once it is known, filtration theory can be

applied in the sense of perturbation theory to calculate penetration of smoke particles

through the screen to estimate the detection time. Spherical coordinates are selected

such a way, that flow enters into the detector for azimuthal angle 0 < ( < 0.

The pressure difference 4p through the screen is given by (Truckenbrodt 1980)

C-174
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

P p - p =q(1-a-csin 2 q7) O:V<Apt (6)

P -pi = (b -ahq 4p > V(

where a is a constant to be determined. Applying Equation (6) into Equation (5) a

similar set is obtained for the flow velocity

_ df q 1-a -csin21p O <o< ,

32aq b-a -a, 2 

By a straightforward calculation one can derive an approximate equation for the air

inflow V into the detector

VI go 0.460 'q 2qf (8) 3237

The used symbols are deltailed in the full paper (Keski-Rahkonen 2002)

SOOT FLOW THROUGH THE SCREEN

(To be completed)

o 0.1 C tv ~~~ 0.1 ~ ~ ~ .1g

0.01

. 0.01 / 

1E-3 1E-2 1E-1 1E+O

Flow velocity through mesh (m/s)

Figure 3. Penetration through a mesh as a function of flow velocity for different

diameters of particles.

CONCLUSIONS

Long reaction times of smoke detectors for cold smoke has been known for long.

Reviewing a series of measurements it was shown, there is a finite value of ceiling

jet velocity, below which the time lag becomes large. It was shown by the author,

that neither any presented model nor also in principle any newtonian single fluid

model is able to explain this threshold. A two phase model is proposed here, where

ideal fluid (air) carries solid smoke particles. At small ceiling jet velocities these

particles are selectivelly filtered out of the flow, as smoke penetrates in the detector

through the insect screen. The presented model was carried over from, and verified in

C-175
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

aerosol reaearch. Still, detailed experiments should be carried out for smoke

detectors for direct comparison with the predictions of the proposed theory.

ACKNOWLEDGEMENTS

This study was carried out as a part of the Fire Safety Research project (FISRE)

which is one of the projects in the Finnish Research Programme on Nuclear Power

Plant Safety (FINNUS). The study has been financed by the Finnish Centre for

Radiation and Nuclear Safety, the Ministry of Trade and Industry, Fortum

Engineering Ltd and Teollisuuden Voima Oy. I am indebted to E.L. Brozovsky for

sending me the original experimental data as well as to G. Mulholland, T. Cleary,

and J.R. Qualey, m for material and fruitful discussions.

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Dover, New York, 1046 p.

Baron, P.A., Mazumder, M.K. & Cheng, Y.S., 1993. Direct-Reading Techniques

Using Optical Particle Detection, in K. Willeke & P.A. Baron, (Eds.), Aerosol

Measurement: Principles, Techniques, and Applications, Van Nonstrand Reinhold,

New York, p. 381 - 409.

Baron, P.A. & Willeke, K., 1993. Gas and Particle Motion, in K. Willeke & P.A.

Baron, (Eds.), Aerosol Measurement: Principles, Techniques, and Applications, Van

Nonstrand Reinhold, New York, p. 23 - 40.

Brozovsky, E.L. 1991. A Preliminary Approach to Siting Smoke Detectors Based on

Design Fire Size and Detector Aerosol Entry Lag Time, Master's Thesis, Worcester

Polytechnic Institute, Worcester, MA, 96 p.

Bukowski, R.W., 1975. Results of Full-Scale Fire Tests with Photoelectric Smoke

Detectors, COM-75-11280, National Bureau of Standards, Washington D.C., 50 p.

Bukowski, R.W. & Mulholland, G.W. 1978. Smoke Detector Design and Smoke

Properties, NBS Technical Note 973, National Burea of Standards, Washington,

D.C.,51 p.

Cheng, Y.S. 1993. Condensation Detection and Diffusion Size Separation

Techniques, in K. Willeke & P.A. Baron, (Eds.), Aerosol Measurement: Principles,

Techniques, and Applications, Van Nonstrand Reinhold, New York, p. 427 - 451.

Cheng, Y.S. & Yeh, H.C. 1980. Theory of Screen-Type Diffusion Battery, Journal of

Aerosol Science 11, 313 - 320.

Cheng, Y-S., Yamada, Y. & Yeh, H-C., 1990. Diffusion Deposition on Model

Fibrous Filters with Intermediate Porosity, Aerosol Science and Technology 12, 286

- 299.

Cleary, T., Chernovsky, A., Grosshandler, W. & Anderson, M., 2000. Particulate

Entry Lag in Spot-Type Smoke Detectors, in M. Curtat (Ed.), Fire Safety Science -

Proceedings of the Sixth International Symposium, 5-9 July, 1999, University of

Poitiers, France, International Association of Fire Safety Science, p. 779 - 790.

C-176
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

Cleary, T., Anderson, M., Averill, J., & Grosshandler, W. 1999. Evaluating MultiSensor Fire Detectors In The Fire Emulator/Detector Evaluator, International

Interflam Conference, June 29 - July 1, 1999 Edinburgh, Scotland, 8th Proceedings.

Interscience Communications, London, Vol. 1, p. 453 - 464.

Farouk, B., Mulholland, G.W. & McGrattan, K.B. 2001. Simulation of Smoke

Transport and Coagulation for a Standard Test Fire, in K. Beall, W. Grosshandler &

H. Luck (Eds.), AUBE '01. 12th International Conference on Automatic Fire

Detection. Gaithersburg, MD, 25 - 28 March 2001. Proceedings. National Institute of

Standards and Technology NIST , Gaithersburg, Maryland (2001), 482 - 493.

Fuchs, N.A., Stechkina, I.B. & Starosselskii, V.I., 1962. On the determination of

particle size distribution in polydisperse aerosols by the diffusion method, British

Journal of Applied Physics 13, 280 - 281.

Heskestad, G. 1977. Generalized Characterization of Smoke Entry and Responce for

Products-of-Combustion Detectors, Fire Detection of Life Safety, Proceedings of a

Symposium, March 31 and April 1, 1975, National Academy of Sciences,

Washington, D.C., p. 93 - 127.

Irvine, T.F., Jr., & Capobianchi, M., 1998. Non-Newtonian Flows, in R.W. Johnson

(Ed.) The Handbook of Fluid Dynamics, CRC Press, Boca Raton, Chapter 22.

Johnson, P.F. and Brown, S.K. 1986. Smoke Detection of Smoldering Fires in a

Typical Melbourne Dwelling, Fire Technology 22, 295 - 310.

Kawase, Y. and Moo-Young, M., 1992. Flow and Heat Transfer in Turbulent

Slurries, International Communications in Heat and Mass Transfer 19, 485 - 498.

Keski-Rahkonen, O., 2002. Time lag of smoke detectors for smoldering fires, (to be

published).

Keski-Rahkonen, O., 2001. Revisiting modelling of fluid penetration into smoke

detectors for low speed ceiling jets, in K. Beall, W. Grosshandler & H. Luck (Eds.),

AUBE 01. 12th International Conference on Automatic Fire Detection.

Gaithersburg, MD, 25 - 28 March 2001. Proceedings. National Institute of Standards

and Technology NIST, Gaithersburg, Maryland (2001), p. 506 - 516.

Knutson, E.O., 1999. History of Diffusion Batteries in Aerosol Measurements,

Aerosol Science and Technology 31, 83 - 128.

Lee, K.W. & Ramamurthi, M., 1993. Filter Collection, in K. Willeke & P.A. Baron,

(Eds.), Aerosol Measurement: Principles, Techniques, and Applications, Van

Nonstrand Reinhold, New York, p. 179 - 205.

Litton, C.D. 1977. A Mathematical Model for Ionization-Type Smoke Detectors and

the Reduced Source Approximation, Fire Technology 13, 266 - 281.

McGrattan, K. B., Baum, H. R. and Rehm, R. G., 1998. Large Eddy Simulations of

Smoke Movement, Fire Safety Journal, 30, 161-178.

C-177
International Collaborative Project to Evaluate Fire Models for

Nuclear Power Plant Applications, Gaithersburg, MD, May 2-3, 2002

Mohr, P.J. and Taylor, B.N. 2000. CODATA Recommended Values of the

Fundamental Physical Constants: 1998, Reviews of Modem Physics 72, 351 - 495.

Patel, N. and Ingham, D.B., 1994. Flow and Heat Transfer in Turbulent Slurries,

International Communications in Heat and Mass Transfer 21, 75 - 84.

Qualey, J.R. Ill, Desmarais, L. & Pratt, J.W., 2001a. Fire Test Comparisons of Ion

and Photoelectric Smoke Detector Response Times, in Fire Suppression and

Detection Research Application Symposium, February 7-9, 2001, Orlando, Florida.

Proceedings. The Fire Protection Research Foundation, p. 385 - 424.

Qualey, J.R. III, Desmarais, L. & Pratt, J., 2001b. Response-Time Comparisons of

Ionization and Photoelectric/Heat Detectors, in K. Beall, W. Grosshandler & H. Luck

(Eds.), AUBE '01. 12th International Conference on Automatic Fire Detection.

Gaithersburg, MD, 25 - 28 March 2001. Proceedings. National Institute of Standards

and Technology NIST , Gaithersburg, Maryland (2001), p. 283 - 299.

Sasse, A.G.B.M., Nazaroff, W.W. & Gadgil, A.J. 1994. Particle Filter Based on

Thermophoretic Deposition from Natural Convection Flow, Aerosol Science and

Technology 20,227 - 238.

Sinclair, D.& Countess, R.J., 1979. Automatic Analysis of Submicron Aerosols, in

D.A. Lundgren, M. Lippmann, F.S. Harris, Jr., W.E. Clark, W.H. Marlow & M.D.

Durham, (Eds.), Aerosol Measurements, University Press of Florida, Gainesville, p.

544 - 563.

Tamm, E., Mirme, A., Sievert, U. & Franken, D., 1999. Aerosol particle

concentration and size distribution measurements of test-fires as a background for

fire detector modelling, 11. Internationale Konferenz liber Automatische

Brandentdeckung, AUBE 99, Proceedings, 16.-18. Marz, Duisburg, Germany, p. 150

- 159.

Truckenbrodt, E., 1980. Fluidmechanik, Springer, Berlin, Band 2,426 p.

Yeh, H.C., Cheng, Y.S. & Orman, M.M., 1982. Evaluation of Various Types of Wire

Screens as Diffusion Battery Cells, Journal of Colloid and Interface Science 86, 12 -

16.

Yeh, H.-C., 1993. Electrical Techniques, in K. Willeke & P.A. Baron, (Eds.),

Aerosol Measurement: Principles, Techniques, and Applications, Van Nonstrand

Reinhold, New York, p. 410 - 425.

C-178
Appendix D: View Graphs Used for Presentations
Contents

Opening Remarks and Research Programs Page

D.1 "U.S. NRC Goals and Plans for Research to Support Risk-Informed Regulation," D-1

Mark Cunningham, Chief, Probabilistic Risk Assessment Branch, Office of

Nuclear Regulatory Research, U.S. NRC

D.2 "Summary of Ongoing Projects at the Fire Research Division at BFRL, NIST," D-7

Anthony Hamins, Leader, Analysis and Prediction Group, BFRL, NIST, USA

D.3 "Future Fire Research at IRSN: Selection and Identification of Fire Scenarios D-17

and Research Needs," Remy Bertrand, IRSN, France

Regulatory Applications of Fire Models

D.4 "First Applications of a Quantitative Fire Hazard Analysis Tool for Inspection D-23

in U.S. Commercial Nuclear Power Plants," Naeem Iqbal and Mark Salley,

U.S. NRC

D.5 "Risk-Informed Applications of Fire Models," Doug Brandes, Duke Power D-39

Company, USA

D.6 "EPRI Fire Modeling Project: A Guide for Nuclear Power Plant Applications," D-51

Bob Kassawara, Bijan Najafi, and Francisco Joglar-Billoch, EPRI, USA

Validation of Fire Models

D.7 "Summary of Validation Studies for the FLAMMES Code," D-69

Chantal Casselman, IRSN, France

D.8 "Zone Model Validation for Room Fire Scenarios," D-79

Olavi Keski-Rahkonen & Simo Hostikka, VTT, Finland

D.9 "The Zone Fire Model, MAGIC: A Validation and Verification Principle," D-87

Bernard Gautier, EdF, France

D.10 "Enhancements to the FIVE Methodology", Fred Mowrer, UMD, USA D-97

D.11 "Zone Modeling Theory, Applications and Certainty - the Verification and D-115

Validation of CFAST," Walter Jones, NIST, USA

D-iii
D.12 "CFD Simulation of a 3.5 MW Oil Pool Fire in a Nuclear Power Plant D-141

Containment Building Using Multi-Block Large Eddy Simulation,"

Jason Floyd, NIST, USA

D.13 "Verification, Validation, and Selected Applications of the VULCAN D-169

and FUEGO Fire Field Models," Louis Gritzo, SNL, USA

Presentation and Tour of Test Facility

D.14 "NIST Large Fire Facility," George Muiholiand, NIST, USA D-179

Preliminary Results of Benchmark Exercise # 2, Part 1, Evaluation of Fire

Models for Nuclear Facility

D. 15 "Specification of Benchmark Exercise # 2, Part I," Stewart Miles, BRE, UK D-189

D.16 Walter Klein-Hessling, GRS, Germany - COCOSYS (lumped parameter) D-193

& CFX (CFD)

D.17 Jonathan Barnett, WPI, USA - WPI Class Exercise D-229

D.18 Amber Martin and Alan Coutts, Westinghouse, USA - CEAST (zone model) D-249

D.19 Boro Malinovic, Fauske Associates, USA - HADCRT (lumped parameter) D-257

D.20 Kevin McGrattan, NIST, USA - FDS (CFD) D-269

D.21 Stewart Miles, BRE, UK - JASMINE (CFD), CFAST D-275

D. 22 "Proposal for Part II of Benchmark Exercise # 2, Stewart Miles, BRE, UK D-287

Future Tasks and Benchmark Exercises

D.23 "Detector Response Modeling," Doug Beller, NFPA, USA D-291

D.24 "A New Model for the Time Lag of Smoke Detectors," D-297

Olavi Keski-Rahkonen, VTT, Finland

D.25 "Proposed Benchmark Exercise for Cable Fire Tests in D-303

NPP-Type Compartments," Marina Rowekamp, GRS, Germany

D.26 "Proposed Benchmark Exercise for Kerosene Pool Fire Tests in D-307

Containment Building," Marina Rowekamp, GRS, Germany

D.27 "Challenges in use of State-of-the-Art Fire Modeling Tools in D-313

Nuclear Power Plant Applications," Bob Kassawara, Bijan Najafi,

and Francisco Joglar-Billoch, EPRI, USA

D.28 "NRC Plans for Fire Tests for Model Benchmark Exercises," D-325

Moni Dey, U.S. NRC

D-iv
U.S. NRC Goals and Plans for

Research to Support RiskInformed Regulation

Mark Cunningham, Chief

Probabilistic Risk Analysis Branch

U.S. Nuclear Regulatory Commission

Goals for Risk-Informed

Regulation

* Commission established new

policies for risk-informed regulation

in 1996

- Focus on licensee activities

commensurate with their significance to

public risk

- Utilize probabilistic risk assessment

(PRA) methods, to the extent feasible, in

a risk-informed regulatory framework

D-1

.S. NRC Goals and Plans for Research 1
Research to Support RiskInformed Regulation

* Availability of analytical tools is key

to success of risk-informed

regulation

* Office of Research, U.S. NRC is

actively conducting research to

improve PRA methods

Key Areas of Research

* Human reliability analysis

- Atheana method developed

* Fire risk analysis

- Fire modeling

- Circuit failure analysis methods

- Significance determination process

- Fire risk requantification

U.S. NRC Goals and Plans for Research D2 2
Fire Modeling Research

* Evaluate capabilities and limitations

of fire models for applications in

nuclear facilities

* Benchmarking and validation of fire

models

* Develop best-estimate methods and

determine uncertainties in

predictions

International Collaborative

Project for Fire Modeling

* Project established in 1999

* Report on 1 t benchmark exercise on

cable tray fires completed

* Contributions from all participants of

significant value to the NRC

* NRC intends to continue its full

support of the project

D-3 [.S. NRC Goals and Plans for Research 3
Memorandum of Understanding

between NRC and NIST

* MOU established in February 2000

* Evaluate NIST fire codes, CFAST and

FDS, for adoption in NRC's

regulatory framework

* NRC staff detailed to NIST

* Mutual interest and benefits to both

government agencies

NRC Proposal for International

Validation Exercises

* NRC will sponsor full-scale tests at

NIST for international benchmark

exercises

* Test program planned for 3 years

from 2002 to 2004

* NRC invites project participants to

exercise respective fire models

* NRC solicits input for program

U.S. NRC Goals and Plans for Research D4
NRC Goals for

Validation Program

* Benchmark range of fire models

- Empirical models used in NRC

inspection process

- FIVE (Revision 1) methods to be used in

NRC/EPRI requantification program

- CFAST and other zone models

- FDS and other CFD models

- Lumped-parameter models

NRC Goals for

Validation Program - Cont'd

* Determine suitable models for bestestimate predictions for range of

scenarios

* Determine margins in predictions for

different types of models

* Determine uncertainty in predictions

.S. NRC Goals and Plans for Research D5 5s
F IRE SAFETY

RESEARCH AT NIST

Fire Research Division

Building and Fire Research Laboratory (BFRL)

National Institute of Standards and Technology (NIST)

http:/www.btrl.nist.govl

Anthony Hamins

NST May 2, 2002 iW~nw hulm" of - dm* ad TdOg7

Tdvo~ogy ~ Abnfr. U& D o9wftnu ofCwiwf

"".. .".|"f.I

D-7 1
I. ~ . - -I e we- %w f '"_..::. ,-.Y:S Y :I.-t§ -1~ ;:.: 1-e1".1- I".. - I- a-

* Staff 5alazies

/-_32 % *Sb2%

D Sules, lel ad Otr Objects

4 *hete* d Rqs nt

Exubrmi Uliveili Grobs

7% a Sn Business Conacts

2% 11% I SdtafBenet snd Overhad

BFRL Fire Research Badt (FY02): STRS ($6 M); OA ($6 M)

Staff 58 FrE (24 PhDs), 25 Guest Scientists (ATF, NRC, Univ.) & 3 post-docs

Backeround: engineers, mathematicians, chemists, physicists

NSr

MaI I Imila. ofsUvndo* ad T s

TchewohwAn~nlmU&cp. LLS DpoComttnuS1. o' f Cmiim."

BFRL Focus: Four Technical Goals

Design P=i ntiomsiOcpMhN; J-R=Oo

EPUAAEC Owner

Life Cycle Facility Performance

NISr 

hbeh o. fbg s, ud ad hnslow h mcg MST "4^ Wwdi,01M *"k~o, UJ D9W*l of Cmwree

D-8 2
Fire Loss Reduction Goal

Cig: Enable engineered fire safety for people, products, facilities; and

enhanced fire fighter effectiveness

Customers: Manufacturers (fire protection equipment, fire

retardant chemicals, commodity polymers); Fire Service;

Engineering fims, Fine testing labs, Building code fllals

Insurance indut._

Design Pocu CoMMuc ommisson OcuyMaint. epenov

. ----- % #1 n_ 

EPC(AEC Owner

Life Cycle Facility Performance

Nafla d _Sndm s a Ta d min t~d 1

. nfr i U Ds f W of Co m~ le C BN190M h41k

Strategy to Reduce Fire Losses (1/2)

Reduce residenialfie deaths, injuries andproperty losses by

* adapting measurement and predictive methods to better understand

conditions leading to P i

* enabling early and certain fire and environment sensing,

* advancing cost-effective fire suppression technologies; and

* enabling new/Improved materials whose fire resistance does not negatively

impact performance, cost, or the environment.

Reducefirefighter line-of-service deaths and burn injuries by

* providing new techne, measurement standards, and training tools; and

* enabling shift to an information rich environment.

Enable cost-effective engineered fire safety for people, products,

facilities, and first responders by

* advancing Rc meaurement and ylon ed

* accunmulating and archiving data, and

* accelerating their transfer to practice.

NIS

Pmndm, d s U'nd w a IWTS&Dw "latl 

Tecbovg M nm*cfn, U Dafiniao o CmmcilwIT1114

D-9 3
Strategy to Reduce Fire Losses (2J2)

Reduce fire fighter and occupant vulnerability in extreme fire

events which threaten homeland security by

* applying measurement and predictive methods to Indga rok f

Jhe in World h%& Center oc. and

* Improving methods otswcgrala OWAor and gt

NOT'

TnoW41mAi**ionw, UL1 DvpailnMM of COnMrM=

Technical Challenges to Fire Research

1010 10 t 106 104 10-2 10° 102 104 (m)

1-9 1 (S)

computational domain

meter-stlck, yr 2000

Challenge: Understand/predict fire behavior over 14 orders of

magnitude in length (and time) scale

Ntsr

b, o.f Slad ad %*dimhg _ Tbd noxoW M,nZd-fek UJS . Dpawmit of Comma mot 96"V5"M

D-10 4
Fire Dynamic Simulator (McGrattan)

- fire protection applications

* performance based design

-fire investigations

. . education/training £1 

* runs on fast PC

* large eddy simulation (LES) of gas phase flow

* mixture fraction

* Finite volume method for radiation transport equation

based on 100+ discrete angles

NtSr 

huuhu. off Sda ed a T..I.a TEcioymiuro LLS Dwnof Cobra

Fire Reconstruction Modeling Project (Madrzykowskl)

*NYC - 3 ire fighters die Inside apt. bldg.

following fashover & wind driven fire

*DC - 2 fire fighters fatally burned In

townhouse ire

*Keokuk, IA - 3 fire fighters die inside

house following flashover

* New tool used to gain Insight Into fire events

resulting In some fire fighter fatalities

* Continuing to improve model capabilities In

response to needs and feedback from

Investigations

NISr

U&-m Mmrola, U.S Dopoctmet of Corcmc

D-11 5s
COMMUNITY-SCALE FIRE SPREAD (R Rehm)

Site Specific Fire Model

* Fire spread between buildings and the

natural environment

* Fire protection strategies

* Quantitative planning & training tool

physics-based fire spread

calculation using NIST FDS model

Full-scale performance data

of building materials and 

assemblies._

93LAPM

Nsr

Naim ha _. o Suwrwa a" TfdM~qff

Tdudqp4tofs~ogon, 14 Depatmw* of Cammws

Large Fire Laboratory Operations (Mulholland)

* renovated facility on-line ($ 7 M)

* implement advanced measurement capabilities ($1.5 N)

*Best-practices to ensure

minimal, quantified

uncertainty reported

NewI m abtwn tema air j

_18MW h{\leat roe _ j _ 02 -depleton calorimetry

* mass flow measurement

New caibratlo burn., in duct using He doping -N b~es t-i New B haraW$f

D-12 6
Wind Effects (Rehm)

* effects of topography & obstacles on wind fields

* effects of external winds on flows inside of the LFL

Simulated surface pressure

on the LFL

I Hoane

"... 91..,.M..AL

Simulated flow vectors 4 m above the ground

near the LFL

Information and Data (Reneke)

Fire Research Information System (FRIS)

* unique fire library (60,000 holdings)

* Planning underway for transition to e-FRIS _7

Fire Data Management System

* create a centralized database of fire data and exchange

format for use by researchers & testing laboratories

Codes And Standards (Bukowski)

* NFPA Standards Council (+15 other NFPA Technical Committees)

* CIB W14 (Fire, TG37 - Performance-based Bldg. Regulations)

* ISO (TAG8, TC92)

d ASTM (ES, Fire Standards,...)

* Korean test method used for measuring fire resistance of wood construction

* Cigarette Ignitability test methods

* ICC Performance Code Development Coin.

NLSr

N 1 - of 4 and *'Tufaw

ob'Adk7. uS DSPNrWmu Of C&t WA

D-13 7
Planar laser measurements of Sprinkler Flows (Putorti)

- Simultaneous sprinkler droplet size & velocity

for input and validation of CFD fire models

* Implement in LFL

* Fluorescing droplets for sizing

* Particle tracking for velocity

* Non-intrusive, instantaneous

* Large area (Im by m)

* Laser sheet. 2D measurements.

* 2 lasers, 2 wavelengths, 2 pulses.

* High resolution film camera

Less Fire-prone Materials Project (Ginan)

Commodity polymers with mn-sized Inorganic layers interspersed can

improve mechanical, thermal & flame resistant properties.

grpielayered PP H_

nanocomposite simulationlI_

As ~silicateday layersin P

viability of high-throughput

to forulate/screen Uapproaches 

sJI~~~~~r~~new fme retardants/fre_

resistant materala explored r

M__a letf " o ad Todl - _

1Wwwkw ~U.s. Oepar1nunt of CWOOMc

D-14 8
Prediction of Fire Growth and Spread (W. Pitts)

Predict detailed fire behavior:

*effects of geometry (realistic items)

_' i -materlals (dripping, bubbling,

chemical effects)

* charring

Challenge: develop a physics-based

pyrolysis model relating fuel flux to

beat feedback

NOTr

Ndobely Cmnr~edit~ D$iti~ie Commerc

Characterization of Thermal Imagers (Wldmann)

Develop an evaluation facility to test the capabilities and

limitations of commercially available thermal imagers.

Infrared viewers see through

smoke for fire fighting

applications.

Thermal Imager Unifcrm hot smoke layer Adjustable surface

I -* : - ,I);4 I temperature

NST 1Z I' time" e dle_ ndf d. ad b_ nwq

Wit o~og~~I~a, UJ Duatm ofCCmwQ

D-15 9
Protective Clothing Project

(EL Lawson)

* Develop instruments & methods for

measuring thermal environments

for fire fighters' protective clothing

and equipment - NIST, USFA,

NIOSH & FDNY

Decision Aids Project

(W. Jones)

Develop a prototype

advanced (smart) fire

alarm panel that will

* identify the location of a fire In a

building

* determine fire characteristics

* operate as part of the cybernetic

building systems

* Develop prototype fire service devices

* standardized graphic/icons for

Information

* scalable, prioritized

communication

* wireless transmission _ NISI

t4Ud Imskt1 o a, d 1a"dimha

Tcfnog Admrtftn, UIS Depwtms of Comn

NIST Response to 9/11 Events

I. National Building and Fire Safety Investigation of the

World Trade Center Disaster

I. Structural Fire Protection

m. Human Behavior, Emergency Response & Mobility

IV. Building Vulnerability

Reduction

V. National Construction

and Infrastructure

Foram

NlOT

bTmdyAdnlofon, US DepaWmm of Conym ao

D-16 10
IRSN Putuv mmisembat N 

* MSN aey in Fire Resech

* Experimental progrms in progress

I Fire scenarios selocted

*e Fire reserch re

MAy 23. 2002 J ta I

IRSN IRSN tafsw ifi.Rmsmh I

U Strategy of IPSN In fWe safety research

Global' approachI 

O Zone Code -

13 Reprosentatlv

test

Ma 2-3, 2002

Detailed approach

d CFD Code Q

a Analytical tests

-i^jp N 2

D-17 I 
IRSN rr|

a FIr Modelling

X Approach of Modelling

put W 11" m"iutif A~oet~ ;akwroh

PLAM Me w 4

To Prode dlfferent Modellng level

#s for 2-3. 2002 i

Msy 2-3200 X Z\Wt f uvi 3 

IRSN ipev6aI prram In wre 

X Representative tests

* FLIP: Fire scenario In a confined and forced ventilated

enclosure

* DIVA: Fire propagation through several rooms

X Analytical tests

* CARMELA: Electrical cabinets

#Ay 2-3, 2002 IAP 51* on '4

D-18 2
IRSN n (umceudssied1) I

U Fire scenarios rankln Approach

X Lists of fire scenarios of each IRSN team:

x Emergency plans

x Deterministic fire risk assessment

X NPP fire PSA

X First ranking by each team (Ignition source frequency,

dominant scenarios of fire PSA or mportancy of releases)

X Last ranking of all fire scenarios

May 2-3. 2002 .W bM eM 5

IRSN Fk..emls Sebted (112)I

Glove lire box lo1 Nuclear facility

cidwse ...~eo I WM4-

I TDP/ftPHre fire 2~ric Nuclear facilt

Fre nvadat 60uan 2' NPePfcl

_owd aov --------

j~~ect~ic~~cablefIire ar* I NPP

A~~~y le2amo3ir IMAW MNP

D-19 3
IRSN _11| NM 

1 TopIks slecti

X Combustion parameters

X Soot production

X Improvement of the plume model In a confined and

ventilated configuration

X Explosion hazards due to the non-burnt residues

X Fire propagation towards other fire sources

X Damage criteria for equipment and electrical cables

May 2-3. 20a1 Xwff*W ., 7

IRSN F .

* Objectivs

* Caracterlsation of the fire source (estabilshement models to estimate

the combustion mass rate, the combustion efficacity, famme spread

velocity)

* Stat of the Art

* Combustion parameters:

HRR * m. S. AH

m: combustion mass rate

S: combustion area

AH: combustion heat

Vf: vitesse de flamme

AH =X. At

X: combustion efficiency

AM: complete combustion heat

Ay 2-3, 2002 MAfP 5ft S

D-20 4
IRSN 11

State of the art (cont)

• Parameters taken Into account

+^, 4ft et Vf are combusti ie caracieristcs

4m et Vfdependt on sie and geometry of the combusdblk, of its

postion vertical or horizonal and of its temperature

4m, Zet Vf change durng thefire scenario

* Tests

4m can be measurd in a coe calorimeter

+Drlngfull scaefire gt the mass oss rate can be measured

continuously but it Is not easy to measure the HRR, moreover

duringflame propagation orfire extingushing the combustion

surface changes strongly

• Usually exdsting data are for unconfined fire (fire over oxygened)

May 2-3. 2002 AMP a.tO 9

IRSN msd

Objectivs ond pproach

X Models for computer zone codes

* to estimate m according to the fire (combustb, geometry, position ...)

* Taldng Into account S evoludon notably duing the fire growth and

witingushing

* impact of ambient confined (02 concenrati CO, C02, soot., Tga&..) on m,

wandz

X Approach

* State of art report fln progress) * In tie first stage, study of fluld and solid combustible without radlonucild

4 Scl effiect on and 

4effect of abxt conAos on - and z

4 Effect of seale and ambnt conditons on Vf

* Development and qualification of a model for a flrst combustble

* Adptation of the model to the combustibles of selected fire scnaros

May 2-3, 2002 JraP ft slfy 10

D-21

5
FIRST APPLICATIONS OF A QUANTITATIVE FIRE HAZARD

ANALYSIS TOOL FOR INSPECTION IN THE

U.S. COMMERCIAL NUCLEAR POWER PLANTS

Naeem Iqbal and Mark Henry Salley

Division of Systems Safety and Analysis

y Plant Systems Branch

W Fire Protection Engineering and Special Projects Section

0

~~s ~

Presentation at 5th Meeting of the International Collaborative

Project to Evaluate Fire Models for Nuclear Power Plants Applications

May 2-3, 2002

National Institute of Standards and Technology, Gaithersburg, Maryland, USA

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF NUCLEAR REACTOR REGULATION

WASHINGTON, DC 20555-0001
PURPOSE

(*,)I

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Support the NRC Goal of using Risk Insights with the Regulation in the

new Reactor Oversight Process (ROP).

(In the new ROP the NRC is moving towards a more risk-informed, objective, predictable, understandable, and focused

regulatory process. Key features of the new program are a risk-informed regulatory framework, risk-informed

inspections, a significance determination process to evaluate inspection findings, performance indicators, a streamlined

assessment process, and more clearly defined actions the NRC will take for plants based on their performance).

* Advance the Fire Hazard Analysis (FHA) process from a primarily

Qualitative Approach to more of a Quantitative Approach.

N)

* Apply fundamental Fire Protection Principles using a simplified

Quantitative FHA tool developed by the NRR staff.

* Quantitatively assess fire hazards at NRC-licensed nuclear power

plants (NPPs).
PURPOSE (Cont'd) is

* * *4

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Evaluate potential for credible fire scenarios that could cause damage

V to essential fire safe-shutdown (FSSD) systems, components or

LA equipment as a part of the ROP.

* NRR developed a Quarterly Regional Inspector Fire Protection

Training/Workshop Program as a part of ROP.

* Sample Problem and Worksheets include in this presentation:

* Radiative heat flux calculations

* Centerline plume temperature

* Sprinkler actuation time

* Heat release rate necessary to cause compartment flashover
CURRENT LIST OF WORKING

WORKSHEETS ** * I

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Compartment hot gas layer temperature and smoke layer height with natural ventilation.

* Compartment hot gas layer temperature and smoke layer height with mechanical ventilation.

* Burning Characteristics of Fire, Heat release rate, Flame height, and Burning duration.

* Full-scale heat release rate of cable tray fire.

* Burning duration of solid combustibles.

* Flame heat flux from a fire to a target at ground level under wind free condition using point source radiation

model.

* Flame heat flux from a fire to a target at ground and above ground level under wind free condition using solid

flame radiation model.

* Centerline temperature of a buoyant fire plume.

* Sprinkler response time.

* Smoke detector response time.

* Heat detector response time.

* Ignition time of target fuel exposed to a constant radiative heat flux.

* Wall fire flame height.

* Line fire flame height.

* Corner fire flame height.

* Compartment flashover calculation.

* Pressure rise in a closed compartment due to fire.

* Explosion calculation.

* Fire resistance of structural members.
GOALS

* to~~

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Support the Qualitative assessment Quantitative values in FHA.

y * Provide a tool which can be quickly used to assess potential for a

--4 credible fire scenario during NPP fire protection inspections on site.

* Integrate FHA tools and risk analysis.

* Over 3 year period, continue to develop more worksheets and improve

upon the current worksheets in use.

* NRR is currently at the 1/2 way point.
NRC REACTOR OVERSIGHT PROCESS

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* The primary objectives of the Fire Protection Program (FPP) at the

U.S. commercial NPPs are to minimize both the probability of

occurrence and consequences of fire.

* To meet these objectives the FPPs for NPPs are designed to provide

reasonable assurance, through Defense-in-Depth (DID) that a fire will

not prevent the performance of necessary safe shutdown functions and

that radioactive releases to the environment in event of a fire will be

minimized.

* NRC new ROP uses a risk-informed approach to evaluate the safety

significance of inspection findings.
NRC REACTOR OVERSIGHT PROCESS

(Cont'd) 4* * A

Y

r'3

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* As part of ROP inspectors use a Significance Determination Process

(SDP) to evaluate the significance of potential fire risks.

* Establishing Creditable fire scenario is an important step to SDP.

* Qualitative methods primarily used until now to evaluate fire scenarios.

* The worksheets add Quantitative values to inspection findings.
METHODS TO ESTABLISH THE FIRE

SCENARIO

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Fire load (BTU/ft2) does not consider these other factors which greatly

Y affect the compartment fire intensity:

* the form of the combustible material (material/thermal properties)

* ventilation openings

* compartment dimensions

* insulating capacity of walls

* NFPA 805, Performance-Based Standard for Fire Protection for

Light Water Reactor Electric Generating Plants, Appendix C, provide

guidelines for detail fire modeling.
QUANTITATIVE FIRE HAZARD ANALYSIS

METHODS **

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Worksheets are modeled after the U.S. Bureau of Alcohol, Tobacco,

y and Firearms (ATF) Fire Investigation Program.

* ATF Fire Investigators use similar approach.

* Selected a series of state-of-the-art Fire Dynamics Correlation from

SFPE Handbook of Fire Protection Engineering, NFPA Fire

Protection Handbook, Fire Dynamics by Drysdale, Principles of Fire

Behavior by Quintiere, and Enclosure Fire Dynamics by Karlsson and

Quintiere.
QUANTITATIVE FIRE HAZARD ANALYSIS t

WORKSHEETS *

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* User-friendly, developed using Microsoft Excel® based on fire

dynamics equations/correlations pre-programmed.

* quickly apply fire dynamic principles found in the handbooks.

* worksheet are protected to prevent tampering.

* automatic unit conversion.

* related material fire property data listed within each worksheet.

* to reduce input errors from in accurate manual entries pull-down

menus allows user to select the single input from the material fire

property data table.
VALIDATION

* *.,,

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* Majority of handbook correlations in worksheets were developed

from experimental data.

* Correlations used in the worksheets were validated in SFPE

Handbook of Fire Protection Engineering, NFPA Fire Protection

Handbook and new SFPE Engineering Guides.
REGIONAL INSPECTOR TRAINING 'f* R t

*

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

Y

* Cover basic principles of fire dynamics, limitations, and bounding

analysis.

* Quarterly training led by NRR Fire Protection Engineers.

* Inspectors independently developed fire scenarios and solve realistic

problems.

* New worksheets presented at each quarterly training session.

* Provided with a detailed manual which contains fire dynamics theory

and basis of worksheets.
CONCLUSION

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

* By taking a commonly available computer spreadsheet software (like

Microsoft Excel"), and creating a series of computational worksheets,

i71 different concepts like fire dynamics can be taught to, and put into

reliable field application by inspectors.

* The use of the worksheet further reduces mathematical complexities

and errors, and promotes greater application of fire science and

engineering in field use.

* The NRR fire protection staff is in the process of developing additional

worksheets for regional inspector application in the area of fire risk

evaluation. The worksheets discussed in this paper are the second set

completed and put into use. A complete suite of worksheets is

expected to be completed in 2003.
SAMPLE WORKSHEET PROBLEM

US. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

This is an example of how to do an engineering FHA using the NRC/NRR fire dynamics Microsoft Excel" spreadsheets.

PROBLEM STATEMENT

During a routine fire protection inspection, a NRC inspector discovers a significant oil leak in a station air compressor. It is

important to determine whether a fire involving 20 gallon spill of lubricating oil from a compressor could damage the safetyrelated cable tray and electrical cabinet in an access corridor in the fuel building. The compressor is on a pedestal

approximately 1.0 foot above floor level and has a 12 ft2(1 .12 M2) oil retention dike. The safety-related cable trays are located

8 ft (2.45 m) above the corridor floor with a horizontal distance of 4 ft (1.2 m) from edge of the compressor's dike. The

horizontal distance between the compressor dike and the electrical cabinet is 5 ft (1.52 m).

The access corridor has a floor area of 20 x 15 ft (6 x 4.6 m), a ceiling height of 10 ft (3 m), and has a single unprotected vent

opening (door) of 4 x 6 ft (1.22 x 1.4 m). The compartment has no forced ventilation. The compartment construction is 1 ft

thick concrete. The corridor has a detection system and a wet pipe sprinkler system. The nearest sprinkler is rated at 165

OF (74 OC) with a RTI of 235 (m-sec)" 2) and located 9.8 ft (2.98 m) from the center of the dike. Determine if there is a credible

fire hazard to the safety-related cable trays and electrical cabinet.

Use the following worksheets to evaluate fire scenario.

1. Heat flux to the target (electrical cabinet) using point source model,4q

2 Heat flux to the target (cable trays) using the solid-flame radiation model, 4,

3. Centerline plume temperature, TP(tedin)
SAMPLE WORKSHEET PROBLEM (cont'd)

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

4. Sprinkler activation time, tact~tn

5. HRR necessary to cause flashover, o

ANALYSIS

Accidental spills of flammable and combustible liquid fuels and resulting fires depend on the composition of the fuel, the size

and shape of the fire, the duration of the fire, its proximity to the object at risk, and the thermal characteristics of the object

exposed to the fire. Liquids with relatively high flash points (like lube oil or diesel fuel) require localized heating to ignite.

However, once started, a pool fire spreads rapidly over the surface of the liquid spill. To perform a conservative FHA, it will

be assumed that the 20 gallons of lubricating oil will be spilled into the diked area and the over heated compressor ignites the

oil.

The summary results of the calculations are given in table. See Microsoft ExcelO worksheets for details of the calculations.

Heat flux to target Heat flux to target Centerline plume Sprinkler activation HRR necessary to

(electrical cabinet) (cable trays) temperature time cause flashover

4 4 q.Tp(centedine) tactivalion (P

(kW/m 2) (kW/m2) [ C (F)] (min) (kW)

12.50 17 689 (1272) 2 2100
SAMPLE WORKSHEET PROBLEM (cont'd)

U.S. Nuclear Regulatory Commission

Office of Nuclear Reactor Regulation

It should be noted that exposure to high plume temperatures could potentially cause the unprotected safety-related cable trays

to fail. The flame heat fluxes to the electrical cabinet and the cable trays are high enough to damage them.

co The results of the calculation demonstrate that a pool fire with a 12 ft2 dike area in an access corridor could damage

unprotected safety-related cable trays and electrical cabinets. The analysis also suggests that for the postulated oil fire, the

sprinkler system, if operable, should activate and should provide some protection to the safety-related cables and equipment.
D-39 1
D-40 2
D-41 3
D-42 4
D-43 5
D,44 6
D-45 7
D46 8
D-47 9
D-48 10
D49 11
The EPRI Guide to Fire

Modeling: An Overview

B. Najafi, F. Joglar,

Science Applications International Corp.

R. Kassawara

EPRI Project Manager

erI2I

IDevelpmmt ofCMTbchnokog0e hnlemuttlo GuIde Appkiafion

 I ~ RM1,1ll12

tDeVeOIPoohscoms totoo modeling

to0ts for.

* Ea of Implemtentation in te fist

*Ufe int PrevtingO Ooresdinfl of basic te modeling pricptos

4educingcostof.Mpisio,

l

DeMolp 5 Sod. foresofdtis

methods snd toots i the NFPA PB

edsrdo6

Ckwto a iiia, -E0.se fire emits dota sputtittlo

rsk so PB eBalssiom

nDetermine roiability of fino pnotectisn

rifenIdeanify sid addness vakness in the

tire risk olosion nott

3LWAJIf--

8/19/2002 Slide: 2 lEPlaZ

D-51
- ~~~~~~~~~~~~~~~ I -Il 

* Introduction

- About fire modeling

- Objectives

- Fire Modeling Guidelines

* Scope and development

* Steps to perform fire modeling

- 5 steps to perform fire modeling

- Supplemental guide

* Conclusions

s~AW~Ems-a 8/19/2002 Slide: 3 aionel

* Fire modeling:

- an approach for predicting various aspects of fire

generated conditions inside a compartment

- requires an idealization and/or simplification of the

physical processes involved in fire events

* Any departure of the fire system from this

idealization can seriously affect the accuracy and

validity of the approach

,> CM8/19/2002 Slide: 4 IFI121

D-52
- * |~~~~~~~~~~~~~~~~~~~~~~~~~~~~

- I '| , j ' IfI 1 :, -

* Exposure

- Fire Plumes

- Ceiling jets Es 

- Upper layer

- Flame radiation

Venuwatiaa

* Effects

- Heat detection

- Target response

* Fire

- Predefined intensity

-d -. - 8/1912002 Slide: 5 Sl~l21

I I

* NPP's present a number of fire modeling challenges

- The ability to address all this challenges is usually restricted by

model capabilities

- A procedural approach can help practicing engineers through the

process of fire modeling

* In response to the need for this procedural approach,

EPRI developed the Fire Modeling Guidelines

Add, 8/19/2002 Slide: 6 SE1=021

D-53
Develop a process through which fire protection

engineers in commercial nuclear facilities may

use fire modeling to support day-to-day operation

of their facilities.

8/19/2OO2 Slide: 7 1=1a1

* The guide is a complement and not a substitute to:

- fire dynamics text books

- code validation studies

- user's guide(s) for a particular code(s)

* The guide does not address the issue of selection of fire scenarios.

* Users with the following characteristics will benefit the most:

- Understanding of algebraic equations

- General knowledge on compartment fire behavior

- General knowledge on basic engineering principles, specifically heat transfer

and fluid mechanics

811912002 Slide: 8 1121

D-54
-~ -i-;' 

* Library of fire scenarios

* Modeling of fire scenarios

- Scenario description

- Prediction of fire conditions

* Lessons learned

- The evaluation of the scenarios generated the

knowledge base to develop the actual guidelines

* Methodology to perform fire modeling

5hAI:.72 8/19/2002 Slide: 9 e I2I

_R~IMSE

* US NPP design and operation

- Typical geometries and equipment layouts

* Risk significance

- Fire IPEEE

* Industry experience

- Utility and NRC surveys: How and where fire modeling

has been used in the past.

- -,t, 8/19/2002 Slide: 10 e I2I

D-55
* Switchgear room

* Cable spreading room

* Main control room

* Pump room

* Turbine building

* Multi-compartment corridor

* Multi-level compartments

* Containment

-aI~ 8/19/2002 Slide: 11 1 2 1

* Issues and

challenges

- High energy events

- Fire barriers

.~~~4IL ~~~8/19/2DD2 Slide: 12 2 ~2

D-56
* Issues and

challenges

- Fire spread in cable

trays; horizontal,

vertical, or sloped

- Fire propagation between cable trays; stack, parallel, or

crossing

- Congested ceiling (with cable trays) and

impact on ceiling let

- Obstructed detection

and suppression

St 8/19/2002 Slide: 13 1121

* Issues and challenges - Fire propagation inside Main

Control Board

- Panel-to-panel fire

propagation and timing

- Habitability

8/19/2002 Slide: 14 ~ =~

D-57
* Issues and

challenges

- Large fires in small

compartments

- Flashover

- Integrity of

boundaries

SIc 811 92002 Slide: 15 I1=E

* Issues and

challenges

- Large fires in large

enclosures

- Non-concrete, open

boundary

- Hydrogen fires

Ai .A 8/19/2002 Slide: 16 SPe

D-58
* Issues and challenges - Smoke/hot gas spread upward

- Fire propagation to floors below

- Size and location of opening and

use of single- or multicompartment model

, S 8/19/2002 Slide: 17 IE1E

* Issues and challenges

- Different ceiling heights

- Soffits and their impact on

propagation of hot gases

s4iC: 8/19/2002 Slide: 18 f1IrIa 

D-59
* The guide does not include a modeling example

for the containment building

* Modeling issues in the containment building are

addressed in other scenarios:

- Large enclosure

- Cylindrical boundaries

- Domed ceiling

fACv 8/19/2002 Slide: 19 Sle2i

Hand CaIcs Zone Models

* FIVE-Rev1

- Excel tool

- Most of hand

calbs in FIVE

- DETACT

- MQH room

temperature

model

* Negli ible

calculation time

* CFAST (NIST)

* MAGIC (EDF)

* COMPBRN-lIle

* Calculation

times in the

order of minutes

Field Models

* Not included in

the guide

* Calculation

times in the

order of hours to

days

r- -a I, 8a19/2002 Slide: 20

D-60
* Microsoft Excel tool with hand calculations included as

Excel built-in functions.

* The library of functions include most of the hand

calculations in FIVE plus the DETACT and the MQH

models for detection and room temperature respectively

* The built in functions combined with Excel capabilities

allow to perform sensitivity and uncertainty analysis.

* Available from EPRI

8/19/2002 Slide: 21 tEIf2I

* Developed in the 90's for a broad range of

applications including buildings, power plants etc.

* DOS based software with a GUI interface

* Multi-fire, multi-room, multi target fire simulation

* Available from NIST

8/19/2002 Slide: 22 -I=I02

D-61
* Developed in the 90's by EDF for a broad range of

applications including buildings, power plants etc.

* Windows based, user friendly graphical interface

* Multi-fire, multi-room, multi-target fire simulation

* Available from EPRI

8119/2002 Slide: 23 S1121

* Developed in the early 80's mainly for nuclear applications

* Still a DOS computer application

- Difficult to input modeling parameters (vs. Windows applications)

- Difficult to evaluate modeling results (vs. Windows applications)

* Single compartment model with one opening

* Uncertainty Analysis

* Available from EPRI

8/19/2002 Slide: 24 MFl2I

D-62
~~~~~~~~~~~~~~~~~~~~~ - I - ~ ,II~ ... ~ 

* Step 1: Define modeling objectives

g * Step 2: Describe the fire scenario

* Step 3: Select appropriate model(s)

* Step 4: Estimate fire generated conditions

* Step 5: Verify and interpret results

5Ad~ 8/19/2002 Slide: 25 e - ra

* Define modeling objectives

- Need to be expressed in terms of output parameters

from fire models

* Example

- "Evaluate the temperature at the surface of the target"

^SUC 8/19/2002 Slide: 26 M a

D-63
I I ; , .: ~ ~ ,~ - 1- ~ '~ ~ .' ,,~ j - : ~ ~ -~ -~ I II ~ -

* Describe the fire scenario

- Compartment: geometry, ventilation, fire protection

- Targets: location, flammability parameters, intervening combustibles

- Fire: heat release rate

* Scenario characteristics are the basis for model selection

* The model may require more or less information than the

one already collected.

8/19/2002 Slide: 27 e(l

I~~~~~~~~~~~~~~~~~~~~~

__I - r 

* Select appropriate model(s)

- The guide provides a table that summarizes the

capabilities of each zone model

- The characteristics of the scenario are required

to use the table

- Additional description may be required based on

the specific inputs to the selected model(s)

'/1' tD<:>:4,8/19/2002 Slide: 28 -

D-64
* Estimate fire generated conditions

- Prepare input file to the model

- Run the model

- Process output file

SW,,:, 8/19/2002 SlIde:29 aIPI2I

D-65
* In many fire scenarios, these 5 steps can not be

readily implemented for reasons that include:

- Enclosure geometry

- Modeling capabilities

- Input parameters

* Supplemental guidance in these areas help

analyst perform fire modeling studies without

compromising technical validity.

* Supplemental guidance is also provided in the

area of interpreting fire modeling results

ARK7. 8/19/2002 Slide: 31 IEI1I-0

* Library of NPP fire scenarios

* Modeling examples of the library of fire scenarios

* Fire modeling guide

* Excel template: Five-Revl

r#>b:e1-~ ,AIC 8/19/2002 Slide: 32 11

D-66
l E>

. - I ~ ~I 1.|1

* Understanding of fire dynamics is essential:

- Physical phenomena

- Assumptions in the development of each model

- Capabilities and limitations of each model

* Combination of modeling tools is usually necessary to evaluate

complex situations in nuclear power plants

* The fire modeling guidelines help engineers to organize information

and select appropriate models

* EPRI is preparing a two-day training course on compartment fire

behavior and the use of the FM guide

b819/2002 Slide: 33 lr-I~ N

* Areas where fire modeling can be applied

- Thermal effects of plumes, ceiling jets and radiation

- General room heat up, and hot gas layer

- Elevated fires and oxygen depletion

- Multiple fires

- Multi-compartments: corridors and multiple elevations

- Generation, migration and density of smoke

- Partial barriers and shields

- Detection

SAEC 8/19/2002 Slide: 34 (r=elal

D-67
, P ., : i~ -1 :. f : ; . . : :..: . 2 .. I t I! .' } .' I_

* Areas for future research

- High energy fires: explosions

- Hydrogen or liquid spray fires

- Fire growth within main control board

- Fire propagation between control panels

- Fire suppression

- Cable fires

* EPRI method uses empirical models based on a

combination of operating experience and applicable fire

tests to estimate consequences of such fires

--n, 8/19/2002 Slide: 35 -Q2

* Duke Power

* Exelon

* Public Service Electric & Gas

* Pacific Gas & Electric

* EDF

* NIST

* NRC

8/19/2002 Slide: 36 a I-2I

D-68
IRSN

FLAMMEfiS code qualification

- 4 series of tests for qualification:

1.: Centred Pool fires (IPSN tests)

2. Pool fires against a wall (IPSN tests)

3. Multi- room tests ; centred fire (Cooper and al);

4. Multi rooms tests ; fire against a wall (Peacok and al.)

E' Objectives of IPSN tests

I. To study the development of a poolfire in a semi-confined

compartment withforced or natural ventilation

2. To study the interaction between the wall and thefire

3NUOM 1

IRSN FLAMfi-S qualification

Fuels

Cbwmcal formla

s TPH

0 70% TPH - 30% TBP

> Ethanol

# Mineral Oil (DTE medium)

i Domestic fuel

r Methane

C12

70% (C12H26) - 30% (Cl2H2704P)

CAO

C31,34H,9

CH4

30M12002 2

D-69 I
IRSN FLAMME-S code qualification

FLIP tests

> fire pool against the south wall

> PLUTON facility : V = 400 m3, LxlxH

9 mx6 mx7,6 m concrete walls

S the normal ventilation flow rate of the room : 3

volume changes per hour.

30)04/2002 3

IRSN FLAbME S code qualification

Area of the

(MI)

0.4

0.4

1.0

1.0

1.5

3042002

pool Mean HRR

kW

360

215

645

510

910

Kind of fuel

TBPnTPH

Ethanol

TBP/TPH

Ethanol

TBP/TPH

Test

FLEPI

FLIPIA

FLIP2

FLIP2A

FLIP7

4

D-70 2
IRSN FLAME S code qualification

Rqerimental data

perimentail e:

Liquidfuel mass

t Plume temperature

O Gas temperature

k Wall temperature

u Total and radiative thermal fluxes on the walls

' Gas pressure

; Flow velocity in the plume

i Species concentrations: 02 C 2, CO, soot (C)

30A4,202 5

IRSN FLAMME S code qualification

Ventilation network

> Admission and extraction flow rates

> Pressures at different location (ex : up and down

strea of the filters)

3P Gas temperature

> Species concentrations : 02' CO2 , CO, soot (C)

304V2002 6

D-71 3
IRSN FLAMME S code qualification

) Data used to qualify FLAMME-S code

Imput data:

v' Mass Combustion rate : measured mass loss rate in

function of time

1 Soot fraction : mean experimental value (mass balance

after the test)

304r"2 7

IRSN FLAMME S code qualification I

Test Data used for the comparison with code results

V Gas temperature: mean temperature, lower zone

temperature, upper zone temperature

v Gas pressure

V Gaseous species fractions: 02 CC 2, CO

/ Wall temperatures

I Ventilation network : gas flow rates (admission and

extraction)

3042OO2 8

D-72 4
IRSN FLAMMES qualification

Comparison of Me experimental and calculated values

Experimental and calculated values plotted on graphes

AO Determination of the relative variations between the

maximum values

> Determination of the largest deviations

Qualifcation criteria:

Relative deviation between experimental and calculated

values less than 20% for the main variables

gas mean temperature, gas pressure, oxygen concentration,

wall temperature

lower and upper zone temperatures interface height

admission and extraction gasflowrates

30i04120M2 9

IRSN FLAMME_S code qualification I

Domain of qualification

s room walls : concrete or of steel.

> height of the room: equal or greater than the smallest horizontal dimension of

the room.

l room : sealed or connected to the outside with vertical openings or with a

ventilation network (flow rate: 3 to 5 volume changes per hour).

o fire pool: centered in the room or against a wall (see FLIP tests).

) fuel: mineral oil or of an organic liquid.

7 the pool area to the area of the horizontal surface of the facility ratio : less than

5%

r combustion rate of the fuel: input data

3 heat release rate to the volume of the facility ratio is less than 5kW/m3

D-73

5
IRSN FLAME S code qualification

Future steps for qualification

- Electrical cabinets fires tests (CARMELA CARMELO tests):

i to develop a model for describing the heat release rate evolution for

this material

First series of tests is achieved ; an empirical model is proposed;

complementary analytical and global tests are planed in 2002

; Multi room tests:

A DIVA tests (first preliminary campaign : 2002) : study of smoke and

heat spreading in multiroom configurations (natural and mechanical

ventilation)

30#04/2O2 If

IRSN FLAMMES code qualification I

Comments:

/ Results are not satisfying for calculation of large pool

fires (ex: 2 MW, 400 m 3 )

Linitation of zones model to simulate fires with large

vertical thermal gradient into the gaseous volume

30/ 12

3OiV4t2002 12

D-74 6
en

Area of the Fuel Facility: Volume m 3 Ventilation Test

pool (LxlxH) ou (SxH) conditions

(m2) wall material

0,0314 Mineral oil 4,35 m 3 confined LPI 7

(DTE medium) (0,856 m 2x5,35 m)

(steel wall)

0,0314 Mineral oil 4,5 m 3 confined LPI 9bis

(DTE medium) (2,011 m x2,24 m)

(steel wall)

0,0629 Mineral oil 4,5 m3 confined LPI 10

(DTE medium) (2,011 m 2x2,24 m)

(steel wall)

1 70% TPH - 30% TBP 400 m3 (9 mx6 mx7,6 m) mechanical LIC 2.3

(concrete wall) (3 V/H)'

1 70% TPH - 30% TBP 2000 mi Natural LIC 2.8.1

(10 mxlO mx2O m)

(concrete wall)

1 70% TPH - 30% TBP 3600 n 3 confined LIC 2.CA

(20 mxl5 mxl2 i)

(concrete wall)

1 TPH 3600 m 3 confined LIC 2.CB

(20 mxl5 mxl2 m)

' The value indicated corresponds to the ventilation flow rate at the start of the fire.
(concrete wall)

y

1 Mineral oil 400 m 3 (9 mx6 mx7,6 m) mechanical LPI 1 1A

(DTE medium) (concrete wall) (5 V/H) LPI 11

PEPSI 1

1 ethanol 400 m 3 (9 mx6 mx7,6 m) mechanical LIC 1.14

(concrete wall) (5 V/H)

2 Mineral oil 400 m3 (9 mx6 mx7,6 m) mechanical LPI 12

(DTE medium) (concrete wall) (5 V/H)

5 70% TPH - 30% TBP 2000 mr Natural LIC 2.8.5

(10 mxlO mx2O m)

(concrete wall)

5 Mineral oil 2000 m 3 Natural LPI 13

(DTE medium) (10 mxlO mx20 m)

(concrete wall)

5 Domestic fuel 2000 m 3 Natural LPI 19

(10 mxlO mx2O m)

(concrete wall)
Q 1/2 /4 corridor Corridor Corridor Corridor Corridor

(kW) corridor corridor and 1/2 door 1/4 door 1/8 door

I _ __ __lobby _ _ _ _

25 x x x x 

100 x x x x x x X

225 x x x x

Ramp x x x x

I fire ,II -

-j

List of Cooper tests T 4' List of Peacock's tests

Test number Q (kW) Door Third room

(corridor)

1 100 Open No

4 100 Open Yes

5 300 Open No

6 300 Closed Yes

7 300 Open Yes

8 500 Open No

9 500 Open Yes
International Collaborative Project to Evaluate Fire Models

for Nuclear Power Plant Applications

Gaithersburg, MD, May 2-3, 2002

ZONE MODEL VALIDATION OF

ROOM FIRE SCENARIOS

0. Keski-Rahkonen and S. Hostikka

VTT Building and Transport

-4/7-

r adzMS MM MM^. t-s

Contents

* Introduction

* Overview of scenario B

* Experimental data reduction for fire model

validation

* Participants

* Results

* Godness determination of the results

* Conclusions

30.4.2002 24

D-79 1
i; nw 1,c1MMIUM

Introduction

* Performance based code usage

* Zone model technology evaluation

* Round robin within CIB W14

* NIST codes considered here

* CFAST

* FIRST

* Excerpt of a full report

30.4202 3

Scenarios

Test label Room size Fire load Fire load density Peak RHR Test time

(M3) (kg) (MJfm 2) (MW) (min)

BI SF83-3 15x7.2x3.5 1989 330 11 100

B2 SF85-10 20 x 7.2 x 3.6 1815 220 14 180

B3 SF86-10 7.4 x 7.2 x 3.6 2 x 500 330 5.2 120

30.42002 4

D-80 2
Testing hall

0 s5 105

Ova-07

:

Subscenario B1 plan view

Side view

I 30..2002

D-81 3
Subscenario B2

-eV-7T 3D.4.a 0 7

I1

Temperature profiles

I E 0 D I II 1---1

i i f L : 

I0 80 e 100 120 140

Time (min) aL

30.42002 8

D-82

4
Layer definitions

T(zi, t) - Tb N

T=z~~ 100N-percent t) rule T (z,,p, t) - Tb 1 00

H

T(z)dz= (H - i )T + iT,

d Quintiere et al.

__ 1d1 1984 (DIM)

f Z (H - ) T+ Z 

0T(z) X0 TL

30.4.2=

l

ljmmlmam

Density integral method (DIM)

TL (II * I2 - H2 )

i + 2T22TLH

H

1 = I T(z)dz

0

I = f

T(z)

4. 2M 10

D-83 5
wa .. :. . su 6 1 2:

Layer height

,V.4.= I7I -I71-w

Temperatures

3042002 12

D-84 6
'Goddness of fit'

E=100% f f 95(t-m (t|dt

E 1 03 ~(t)

f 0 m (t) *9 (t)dt

E,,= 1o0% . to () to 0 m0

-lo(tO.m(t)dt 119 (t. ) )d )d(t 

= 100% to 

f 9, (t )dt

0 PvL 30.42002 13

Mean relative errors

Code

Variable

ARG CFA MRF FIG FW FST FLS FIS Average

T0pB i 25 13 14 14 21 21 48 26 23

T, B2 27 27 25 26 NA 15 36 33 27

T, B3 32 10 20 12 NA NA 41 35 25

Average 28 17 20 17 21 18 42 32 24

h5,,0, B 1 72 23 14 27 20 19 25 19 27

h5 ,,,, B2 69 62 81 88 NA 86 70 65 74

h5 0,, B3 54 36 10 28 NA NA 51 32 35

Average 65 40 35 48 20 52 49 39 43

A 2 B a 3.3 2.7 2.0 3.0 7.4 1.7 1.1 1.8 3

AO2 B2 37 38 36 31 NA 54 53 38 41

A 2 B3 31 34 42 43 NA NA 175 67 65

Average 24 25 27 26 7 28 76 36 31

-AVT 30.42= 14

D-85

7
Izmmzi

Conclusions

* Results improved from blind to open simulations

* Selection of alternative submodels important

* Deviations from experimental data 10% ... factor of 2

* The user the most critical factor

* CFD calculations was not superior to zone models

3D.4202 15

D-86 8
-aj

II,~~~~~~Ia

Barrad GAUUER

EDF R&D

8, qiui waUr. 78401 CI4ATOU FRance

eDiscusSIon on0 th oelV~agn 

Short the M AGsICva da lon 

am :

Page 1 1
a

A nul modal rink tram It.. umodaUmaE vdouub.nadds:

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Page 2

2
vadhy doi.

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am

--

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Page 3

3
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Page 4
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Page 5

5
I ' S . . .. ..

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Page 6

6
T

t~~~~~~~~~~~I : floW&itIa :,,

* lbmudim1Minthrim. oaN

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secondary %op"tMins

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Il -

~~~~~~~~~ -~~~~~~~~Pw 1m

Page 7 7
- * 

O8ON5k.gazbrn,1381 mI 

I~ ~ - -

k~~~~~~~~~~~~~~~~~~~~~~~~~~N

1 O,g * *9

.Fmac.:cEA cads ________

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Page 8 8
y

tn

Enhcmet cd the validabion tGoe; -Taargatsiperaturo: fkwbaeboe than gas temp admore :

r oelevat for rsek stud

~. U

.. M) -

bo"::f: 

: : 0 : :~~2

I I I . 0 . 0 . -- U - - -

ho* ldatonFile is thekey ofaea p tan.

* Rds$e nd a lai flod if et mknent q data is knporba

* Testsmsbeod quali y,w e _ n a iep byth osciotwifc 

u audy. - - * l lb.: p ss fcb o dv all t use I ci ped entcimoe lng; , colces and av-ilvablo t oo' user. :6 

* Th results odd with MAGICma a etin spenWal data has 8a6d iadouatr uh ina o en0 o s, heatrlee mi cn fgumta m i

: U: I~~ 0 :

Page 9

9
Enhancements to the

FIVE Methodology

Frederick W. Mowrer

Fire Protection Engineering

University of Maryland

18 6

A Ls1~

Acknowledgements

The "heavy lifting" for this project was

performed by Francisco Joglar-Billoch,

currently with SAIC

Partial support for this project was

provided by Brookhaven National

Laboratory and the USNRC

m 2002 F.W. Mowrer FlreMD - Slide 2

D-97

1
Background on FIVE

Developed by EPRI in early 1990s for nuclear

utilities to use in IPEEEs

Included two parts

* Overall methodology developed by PLC

* Methods of quantitative fire hazard analysis

developed by Mowrer

Fire hazard analysis methods intended for

screening purposes

o' Widely used for qualification purposes

0 2002 F.W. Mowrer FireM -Sie 3

The FIVE methodology

Developed as series of lookup tables for

one-zone one-room analysis

6 Average gas temperature

Unventilated enclosure (base case)

Naturally ventilated enclosure

Mechanically ventilated enclosure

'Fire plume sublayer

o Ceiling jet sublayer

3 Thermal radiation

0 2002 F.W. Mowrer FireMD -Slide 4

D-98

2
0465'7

18 56 The FIVE methodology ,&_,Barney, IMM

2002 F.W. Lwer FlreMD- Side 5

The FIVE methodology

2 Average hot gas layer temperature

AvTg = T [exp(Q,,, /Q 11

; Plume temperature

ATpi = ATavg +25 3 5/3

2 Ceiling jet temperature

a7e>_ 0.32

6 2002 F.W. Mowrer ATM ( / H ) 2 /

3 FreMD - SJide 6

D-99

3
FireMD features

A one-room two-zone fire model with the

following features:

Implemented In Access and Excel (97 / 2000)

S Natural and mechanical ventilation

Floor / wall / ceiling vents

Specified injection / extraction rates

a Plume / ceiling jet sublayers

* Detection algorithm with RTI / conduction

* Target / boundary heating

0 2002 F.W. Mawrer FIreMO - Slde 7

FireMD diagram MO?$. S,,h aVMW

jM0 2002 F.W. Mowrer FtreMD - Slide 8

D-100

4
FireMD - General

0 2002 FW. Mworr FirMD Slide 9

FireMD - Fire

0 2002 F.W. Mowrer FireMD - Slide 10

D-101 5
1..? 0. AAeo~f

FireMD atla - Compartment idAls~'SA'>mg .§.~~,3i-.~_ I ii .. a' fB'i ~iE/;<Ri I 'iZs9Ss~U ............... .

I>i

0 2002 F.W. Mowrer FlreMD -SlIde 11

St, FIreMD - Ventilation~~~~~~~~~~~~~

0 2002 F.W. *Slide 12

D-102

6
FireMD - Plume / CJ R

- 200 F.W .Mowrer Fire Sid e 13

.~~~~~~~~~~~~~~~ [

,~~~~~~ :

4 9

S -. t s.. 9 

P~~~ E ¶,g| 

.,. 9 ~S ; E

0 2002 F.W. Mowrer FlreMD Slide 13

FireMD Detection

_ I

5 1l

0 2002 F.W. Mowrer FreMD Slide 14

D-103 7
c,

jJ, 4

FireMD - Results D;,&'" ':Z,  Ro,LaKy,Lm- I u', W 11 0,1 11 . I 11,,,, I ZL  ,4-,  I;

0 2002 F.W. Mowrer FIreMD - Slide 15

D-104

8
FireMD - Temperatures LoNws ..: I~s< ..3, i., ._:_. . z z: . .... ,,l 4t. e ^ w .v- E" S`, T' .'.7'-k' s E e .,C2X.,. -7 ' 4

- s

- 5

- 41

-31

eto 0

am

How

0 2002 F.W. Mowrer FlrelMD - Slide 7

FireMD - Pressures

0 2002 F.W. Mowrer FireMD - Slide 18

D-105

9
FireMD - Ceiling/floor S6Sit<L&-a<;~, P I s 6 ^_ MWI > WQraa g ;>I:^u -- ~ ki Bij~i s< m~ X~vs -

l8 5

DRYL

stng. ;..w. .j.A- .

0 2002 F.W. Mofrer FIreMD - Side 19

FireMD - Vertical flows M vft . , q"," z !,,,Afghanistan,

0 2002 F.W. Mowrer FireMD -Slide 20

D-106

10
FireMD - Heat fluxes

F W E20 More FgM Slide 21

l 1( .I ^ ', 2 :. . |Heat Fluxsto Boundghs 

Omor

~~a3 -- - NtROCH~-NdOFH- a NotRFHw E

2002 F.W Mwrer FlreMD - Side 21

I

F. Sty',S

FireMD - Detection

fteDeft Tommob"w

~~ ~~~ 20W 20~~~2

2001t 20~ 

20rn .~~~ ~~ 2049 000 m a

-Tdi -CJTrO

0 2002 F.W. Mower FireMD Sld 81e22

D-107 11
FireMD - Target

11 2181 02-~-H~k

a . C . am

0 2002 F.W. Mowrer FlreMD - Side 23

FireMD validation studies §

FMSNL baseline validation enclosure fire

tests

LLNL mechanically ventilated enclosure

fire tests

0 2002 F.W. Mowrer FireMD - SlIde 24

D-108 12
FMSNL series

Enclosure

A18.3 m (60' x 12.2 m (40' x 6.1 m (20) high

Fire sizes / durations

a 500 - 2000 kW / 10 - 20 minutes

Ventilation

Mechanical injection through 6 vents located

1.2 m (4' below ceiling

0.4 - 3.8 m 3/s (1 - 10 changes/hour)

0 2002 F.W. Mawrer FreMD - Slide 25

FMSNL instrumentation

05 15.0

3A 79 A 6

N l20 ' U I® 

30) 20 A 1e 

A,- Sectors .- Corner Rakes

0 - Expanded statlons - Exhaut Port 0 -StalIone - Vent In et Ports

- Fire Sdurce Lomati ona

0 2002 F.W. Mowrer FireMD - Slide 26

D-109 13
FMSNL series

Test 4:

1 air change per hour (0.38 m 3/sec)

Peak HRR = 500 kW, Growth time = 240 sec.

Test 5:

10 air changes per hour (3.8 m 3/sec)

Peak HRR = 500 kW, Growth time = 240 sec.

Test 9:

8 air changes per hour (3.3 m 3/sec)

Peak HRR = 1000 kW, Growth = 480 sec.

O 2002 F.W. Mawrer FireMD -SlIde 27

D-11O

14
V.P So'

FMSNL Test 5 R

Upper Layer and Plume Temperatures (Test 5)

120-

Plume Temp

E7 U° 0 A,

40

el-lo Up~~~~per Layer Temp

20

0 50 100 150 200 250 300 350 400 450 500

Time [sec]

0 2002 F.W. Mowrer FreMD -Slide 29

FMSNL Test 9

Upper Layer Temperature (Test 9)

100 

- FireMD

80 Data collected from

- ~~Station 10. tp

n. 61)1

40-

20

0 200 400 600 800

Time [sec]

0 2002 F.W. Mowrer FreMD - Slide 30

D-111 15
,P SI,)

LLNL series (Mod27B)

Enclosure

6.0 m (20) x 4.0 m (13') x 4.5 m (15) high

Fire size

Steady 400 kW fire

Ventilation

Mechanical extraction at 0.25 m3/s through vent

located 0.36 m (1.1) above floor

Makeup air through 0.24 m2 inlet 0.1 m above floor

0 2002 F.W. Mawrer FireMD -Slide 31

LLNL Mod27B

Upper layer temperature

t3eAMp. *. aud C*IUag Jet TUpear.1

300

li. W.~ ~ : ~ ~ ~ ~ ~ ~~~~3 ) r~~~~~~~~~~~~~P.~mai

tO0 _~~~~~~~~~~~~~~~~~~~

0 500 1000 1500 2000 2500 3000 3500

0 W 00 1500 . .2WV 200 20 00 T.im it-al]

0202o.-reUp"L Fre -Sylide2

0 2002 F.W. Mowrer RireMD - Slide 32

D-112 16
LLNL Mod27B

Oxygen concentration

2S

X m ~Tim l r's w ,

0.

0 50 IODO ISOO 2000 200 300 350

Tr [..I

D 2002 F.W. Mowrer FireMD - Slide 33

1fr50

LLNL Mod27B

Wall heat flux

Total Beat "MC to Walls

4f00

3000

.,X; _ + ff ff ~~~~~~~~~2000

D . t l | 4 I | I | ~~~~~~~1000 o e 50. lw laoe ! 1 2Dt

0

500 1000 150D 2000 2500 3000

.1000

Tw 1s]O~

0 2002 F.W. Mowrer FireMD - Slide 34

D-113

17
I

LLNL Mod27B

-- Inlet / outlet air flow .

.

.*W- ab"awftw . im - aftfts"Sivi

I: ", , I". h, Ai-1-AL

-.- j!T"P:WT1n t' V

..f. 41 4 i. - M I i"

Ft.wThb,.S V.MU.. Optag

i 0.20

.0.10

.0.10F 

Tb.. br.l3

0 2002 F.W. Mowrer FireMD -Slide 35

Summary

FireMD provides useful enhancements to FIVE

FireMD predictions compared with experimental

measurements for a range of enclosure sizes,

fire intensities and ventilation conditions

4 FireMD predictions are generally within 20% of

measurements for temperatures and flow rates

Further work needed on 02 concentration and

higher temperature fire conditions - No work currently being done on the model

0 2002 F.W. Mowrer FireMD - Slide 36

D-14 18
Verification and Validation of

CFAST

Walter W. Jones

Analysis and Prediction Group

Building and Fire Research Laboratory

5th Meeting of the International

Collaborative Fire Model Project

May 2-3, 2002
N .

The Three Legs of Modeling for

Public Safety

* Zone Modeling

* CFAST (and the GUls)

* Validation and Verification

* Through statistical analysis

* Data for comparisons

* FASTData database development

May 2, 2002 l7ft
N IModeling

* CFAST -zone model

* Large (complex) building simulation

* Inputlmodel/output Yi

H

* FAST/FASTLite/F i reWalk/Fi reCAD

* GUI interfaces for fire models

* Includes simple back of the CRT calculation

May 2, 2002 17M
Nu5.

Concept of a Zone Model

Each compartment is subdivided into "control volumes,"

or zones. Conservation of mass and energy is

V applied to each zone.

X0 A few zones (2 to 1 0)

Predictive equations are derived from conservation of

energy and mass (momentum at boundaries)

Use ordinary differential equations rather than partial

differential equations

Adding phenomena is relatively easy

May 2, 2002
Nu I

Concept of a Zone Model

...... Y. r

r~~~~~~~ 77,~~~~~~per~e

QFORL

May 2, 2002
NuS,

Why Is this Modeling Important?

* Speed - algorithm implementation is very important

* Do parameter studies of complex buildings

* Complex and numerous connections

* Predict (small variations do not matter)

* Environment (CO, mg)

* Insult to the structure

May 2, 2002
N I -

Zone Models in the U.S.

CFAST - 2.0.1 - HAZARD I version 1.2

CFAST - 3.1.5 being used in fire reconstruction

Compbrn I - UCLA - consulting with EPRI

BRI2 (Japan) - Factory Mutual Risk Analysis

Many specialize tools such as FPETool (ASET, ASCOS, ...

'-

May 2, 2002 QFRL
Phenomena

Multiple compartments (60->~100)

* Variable geometry

Multiple fires

* Ignition: time, flux or object temperature

Fire plume and entrainment in vent flow

Vitiated or free burn chemistry

Four wall and two layer radiation

Four wall conductive heat transfer through multilayered walls,

ceilings and floors

Wind effects

3D specification of the location of the fire and non-uniform

heat loss thru boundaries

May 2, 2002 a
Phenomena

Generalized vent flow

* Horizontal flow (doors, windows, ... )

* Vertical flow (holes in ceilingslfloors)

* Forced flow (mechanical ventilation)

Intercompartment heat transfer

Ceilingifloor

Horizontal - compartment to compartment

Horizontal smoke flow

Detection - smoke, heat

Suppression - heat releae knocKdown

Separate internal and external ambient(s)

May 2, 2002 IRA.
Nl

Intercompartment Heat Transfer

(Horizontal Conduction)

Flux at rear of room 1 = weighted

average of fluxes from front of rooms

2, 3 and 4 or ...

q~r= Fjq#f-: 0-:::i ::I V i,avg I

t'a

4 _ _O

qiavg Average flux at rear of wall i

F. Fraction of flux from the front of wall j

contributing to the back of wall i

qJ Flux striking front of wall j

Wall joining compartments 1, 2, 3,4 Frontwall(compartment1)

Back wall (compartments 2, 3, 4)

Front wall (compartments 2, 3, 4)

Back wall (compartment 1)

May 2, 2002 qiFRL
N)

Ln

N IXYZ Positioning of Objects, Fires and Surfaces

z=HR DR = Depth

BR = Width

HR = Height

|(opo,o~ *0 = BR

Center =(DR/2, BR/2,O)

x= DR

May 2, 2002 1 ,FRL
N I

Vertical Flow

(Horizontal Vents)

0o t I,

Horizontal

Vent

May 2, 2002 QFRL
N***

Corridor Flow

$EM 1 I Z PME "M "ME KAUJL 2.4

2.2

2.0

la 

1.5

I 4

.5

.5

.4

.2

0

I? a I I 4 a

MgJMFA

* 7 I 3 la

2.4

2.2

2.0

I's4 Z.5

.4

.2

a

0 1 7 a 4 15

MC1Ke

a 7 a 3 10

May 2, 2002 QFRL
N 

Leakage - Specification Errors

0% -- 10 - 50% --- 100%

0

-2

0.

2000

1500

1000

500

-4

-8

-1

-10 0

0 100 150 200

Time (a)

May 2, 2002 FR.L
Nc I

Effects we can examine closely

0

E

-

0

0

4000

2000

D

-2000

-4000

-6000

-8000 _ 250

I I I I I I I

* Extended coiling fx using RA2

V Ceiling flux using R4

* Upper well flux winig RAD4

I I I I I I I

300 350 400 450 500 550 600 650

Ceiling Temperature (K)

May 2, 2002 NZIMl
NU-.

Verification vs Validation

* Verification: insuring that the phenomenology is

implemented correctly in the model

* Validation: insuring that a model makes the

correct (expected) prediction for a given set of

input data

* For public safety and finding economies of scale,

both are important

May 2, 2002 OML
N m.

Issues Related to Verification

* Comparison with experimental data, including error analysis

* Open system - published code (verification, not validation)

Y

* Documentation - crucial

* Sensitivity analysis (suite)

May 2, 2002 lifL
Niu

Quotes on Verification

* "The simulations generally compare favorably with the experiments"

* "Upper layer temperatures were not predicted well by either model"

* "Layer heights are well predicted by both models only in the bum room"

* "All of the models simulated the experimental conditions quite

satisfactorily"

* "For the 4 MW fire size, all of the model do reasonably well"

May 2, 2002 qFRL
N .

Statistical Verification

1

0

ytH

t,

(A -0

c

-

CD

C

-2

-2

0 500 1000 1500

Time (s)

May 2, 2002 QFRL1
N 

Possible "Norms"

-II p I I lx 11 \ X 2

i

1

Y

n

i=l

(Xi - Xi- Yi -Yi-I)

X31 --OI --.

*

y =

t. - tMay 2, 2002 QFRL
N .-.

Example of Metrics

Expeiment

Model I

Model 2

Model 3 'i

w

U1

W

E(D

2!

w

GMV

r"

2D-

* /

/

I

/

product definitions

Geometry Model Relative Cosine

Difference

Euclidean I 0.10 1.00

2 0.40 0.92

3 0.20 0.98

Hellinger 1 0.10 1.00

2 0.94 0.58

3 0.74 0.77

Secant I 0.10 1.00

2 0.92 0.58

3 0.66 0.83

Hybrid 1 0.10 1.00

2 0.64 0,78

3 0.43 0.91

_ _ . . . ................... _ 4__ ................... e _ _L__

0.

I I I - .I S

0 2) 4 ei S) am

TrB

May 2, 2002
No-"

One of our real room comparisons

E

o 1 000 

_ Rel. Diff. = 0.36, Cosine = 0.95

S

C

800 Rel. Diff = 0.31, Cosine = 0.93

4.

F-4 6 0M 0 | 

0) 0

at 200 - jI - -- ~~~~~~~~Experiment

0 S~o 1000 1 500 2000

Time (s)

May 2, 2002
N _~m.

1, 3, 4 and Multistory Configurations

r-- -- -- - -- - I

A

22W

Il

0

H a]

U-CWidw

Imlu I - I

--j

* F"lY .W. 

~4 * H.en~m Wun wmm"u, ICO Gs as & U GWM#AS_ M CM auU. * S_"Pm&w _

I

11

FwuuM W kW

* FkSUOUUg b9W

o Aw"naasKw

Humfhmxb1

* 00ruMdm (00. 00 a 02

H am vMOONy Tw

%S 4.. a-+ +

mw

Fkouinaw.bflw

* Owmhm tumyuuix Pig)

a GuamommiNW1,0OM0

Gkm amuk*00i ( OD 0)

p4 DiIjpmwnmwnw

A mae. uonmi

Rr uaur% WpOmen mtm ke

GM concmnurg

Doreflu pemmo u (oom 2 to room 4

do May 2, 2002 QF,3L
N.>i

An example with four real scale experiments

r I~~~~~~~POSWtOU/ I1~e~ve TRelatve

IflO...Artin Dference lCoine D)ifference cosine 'ienc cosine

Upper Layer Temperature ~~wr~e .prtr LtraePsto

WUMQ ea- ... ... 6 Q.....4-1.-

........... 0.93,2 0.9 -0 10 0.7..9 

W"--t PresureQ Release. and Vent Fl.

~~~~~~~ .81:z:..,1~~~~~~~~~~~~~~~~~

.~~~~~Z92 _ KQ~~~~~~~.1 P-4

May 2, 2002 QFR. L
N. i

Steps for Verification

* 1) Maintain a set of test data: small scale to real scale

FASTData (US), several others; not as useful as it should be

* 2) Maintain a set of data files which have given us problems in the past

Many of these are usability issues, but that affects predictions as well

* 3) Do are formal comparison of a "released" model with the results of past

calculations

bintoasc, compare, compinfo - variable.dat includes allowable variance

Appendix in technical guide

Did through 3.1.6

* 4) Maintain a history of CFAST - earliest is March, 19894

In principle, one can reconstruct the executable for each release including intermediate

versions. In reality this is not a practical exercise.

May 2, 2002 NWRL
N IConclusion

Validation and Verification are important

Statistical comparison (with metric) is possible

Needs more work

y

CD

May 2, 2002 NIZM

,IN
Numerical Simulation Of A Compartment

V Fire In A Nuclear Power Plant Containment

H

Building

Jason Floyd

May 2002
Overview

* Multi-block FDS

* HDR facility and the T52.14 oil pool fire test

* Results
FDS

* Fire Dynamics Simulator v2 (Dec. 2001)

* Computational fluid dynamics - LES/DNS

* Building and Fire Research Laboratory, NIST

* Submodels

V - Mixture fraction combustion

- Finite volume, gray gas radiation

- ID heat conduction

- Pyrolysis (solid and liquid fuel)

- Sprinkler dynamics and droplet evaporation

* Smokeview for data visualization
Multi-Block

* Single-block: One grid used to span computational

domain

* Multi-block: Multiple grids used

* Multi-block can reduce the number of grid cells at

the expense of more complex boundary conditions

* For some problems the grid cell time savings >>

boundary condition time penalty
Multi-Block Example 1

* Resolution needed for the fire > resolution needed

for smoke movement Uk~~ 0- r -

EMMON _l~- ilS MEME 

Vn l_

10000 Cells 1400 Cells
Multi-Block Example 2

* Complex geometries may

cells

result in many dead

0an

1600 Cells 1120 Cells
HDR Facility

I

+ 50.00 .

* Decommissioned Main PenSoNUel

Sti + 40.00 

containment building in

Karlsrhue, Germany

Secoebau

Equipment

Hatc\

TS2 Fure

RoOM

.- 4Aevator

Sha[

Rescu + 30.85 .

Y. * 20 m diameter + 25.30

* 60 m high Semirdary

Spl-]

Stay

Eqnent

H oatway + 20.60 s

(Gentrally

Opt)

* 8 levels

* >60 compartments

* 1 1000 m 3

* 5 vertical flow paths

U41, E42

lr Raem

T51 ire

ReCWA(O"

Of mmue forTipk Crew

So&ie)

+ 15.05s

+ 10.00.

+4.50.

-1.10.

-11.00-

270' 90.

I
HDR Fire Testing Program

10000-

7 test groups kW

* 33 tests

co ~~~~~~~~~~5000- * 4 fuels: propane,

wood, oil, and cable

4 locations 4g~ 4 T s

2 30 kN V to > 1 0 IN'W Gas 1 Wood Cnbs Gas 2 Hydrocarbon Hydrocarbon Hydrocarbon Cable Fire 230 >10 kW to M W ~~~~~~~~~~~~~~Open Open Closed

T51.11-19 84/85 T51.21-25'86 T52.11-15'87 E41.1-4 '88 E41 5-10 '90 E42 '91

Level 1.400 Level 1.900 Level 1.500
T52 Test Series

* Four tests (T52.1 1-T52. 14)

* Liquid hydrocarbon fuel (Shellsol T)

* Level 1.9 (Below dome operating deck)

* 1 mx 1 mto 1 mx3 mpools

* Measured temperature, velocity, CO2 throughout

facility
T52 Test Layout

('

0

R .902

38 .

.C

0Z

Hatch

j

18

E

a)

R 1.908

Fire Room

E 1.78 m

E

rwayI ~~~CM

1.00 m

0.2 MT

Doc

- I I H'atch H a t c h I . I .I I .I .. . .. . . .w v .
Test T52.14

0.12

0.11 i_

0.10

0.09 I _

9' -0.08

It 006 

.0.06

0.05 C ~~~~~~~~~Constant Oil ________ ~Addition 0.04

0.03 Burning of

Initial Oil

0.02 

0.01 I _ I 

o.00< 1 0 20 30

Time (min)
Input Parameters

* Fire Power: 2.65 MW (Steady-state power)

* Fuel

- C 12H 26: 170 g/mol, 42500 kJ/kg

Hi * Surface definitions

- Fire room: firebrick

- Walls of hatch area: fire resistant fiberboard

- Remainder: concrete
FDS Model

* Fire room, hatch room, dome

* Steady state portion

* Three grids, 650,000 grid cells:

- Fire room, 10 cm, 48x25x32 (38 knodes)

F-IY~ - Hatch, 10 cm, 40x36x72 (104 knodes)

- Dome, 25 cm, 80x80x80 (512 knodes)

* One grid ,10 cm, 1,216,000 grid cells

* Also ran 3/4 linear resolution
FDS Model

_. *...... "....* .. Z..Z~". .......... Z........ .H

a na ME ---- -a 

_: .'.fu2 o"M ,::n:::mpnqn:ra:::::::6a 'llsom"M- mln--i a :::::::::: *a- jhjaai H'Ms.N. 

-SSESSS..it.:is.,iai*nasanamaannau5aaaaammaaaaamammamai a::.anm aanuaa.uu.a

|w_.l~~..:L l!::::::::SESsEE j~ p am naaaaalaaaamm 

i-, ruh.asam aamaasaaaamnmaag.a am ma agmaam::wag: sas% ma::ma

Us a.;..:l:.^|saau..5.:::.L jam ,:3-ss"::::s! .aaoi -ani

a~somnafffh gmsaaausaaaa. anmsaamals

anasms. 1 ema..as .smmnss Meaa uaama Uamsaa m Xn

ssaasaasmaassaass8sssaaalaaaaaa iiua aaaaanaaamaaaaaaaasaaamasaaaaaaaaa aammminsaan m aimassa Y ammaaanmaasaaaaasaaasaaaaanaaaaaamaaamamaamaa a ama as samamama, ataflaaaaaa~~~~~II' m~~~~~~sdh:;2:lr~~~~~~~ C

I-' aaaaaaam aalaaaasaaaaaaannaaa aai,2"*I a

Elwmalaaaammmsma22be aasa owmelEaasa*aaa-Ism mam mmmmsifimamlmms Ln so Me was~~mata~a~ima aaaafFltmam anu
Time Required

* 2.2 GHz Pentium IV, 1 Gb RAM, Linux

- Full resolution case (654,080 grid cells)

* 7.5 min CPU/s realtime

iy - 3/4 resolution case (275,292 grid cells)

2C

Lq~~~ 2.5 min CPU/s realtime
Integral Fire Room Results

Parameter HDR Hand* FDS 3/4 FDS

hn (m) 1.4 1.0 1.2 1.2

Tout (C) 870 1210 793 827

(kg/s) 1.90 2.13 2.30 2.14

Us

as

M-

*Hand calculation following -layer method of

Karlsson and Quintiere, 2000, Enclosure Fire Dynamics,

CRC Press.
FDS Flame Surface

C 7 W

1-'-; ' a "l'-,* . .', r, v. T~ ~*~ W4 ,. .j4 
Fire Room Doorway

8

7 HDR A 1400

6 =_ _FD 34 

6 1300 20 _ _ _ _ F 12 I / ____ 00F

1100

1000

-2 a60,, 0 - _ - -

-3 , ! , 00

k -0~~~~~~~~~~~~~~~~~~0

-I 2~~~~~~~~~~~~~~~~00

100

001
Plume Animation

kul

I pf Oevdav I
Hatch Temperature Full Grid

Tempeature (C): 0 40 80 120 160 200 240 280 320 360 400 440 480

5.00

4750

4.50_a. : .fX .; ;.;.,.g .+

Temperature (C): 0 40 80 120 160 200 240 280 320 360 400 440 480

y

4.25

>I 4.00

3.75

3.50

3.25

>` 4.00

2.50 J .J 

x ()

3.50

x ()
Hatch Temperature 3/4 Grid

T

o

Temperature (C): 0 40 80 120 160 200 240

5.00

4.75 W 

4.50

4.25

4.00

3.75

3.50

3.25 _. 2 i; .,

360 400 440 480 

-I nJ

5.00

4.75

4.50

4.25

Temperature (0C): 0 40 80 ,120 6 200 2

|Temperature (C): 0 40 80 120 160 200 240 280 320 360 400 440 480|

>'- 4.00

3.75

3.50 . Hv - i ..

.. AVi'S :0: :: 70S S E ?- f ,,:f

iD o y c:e

2: V

t; .g'I'

4.50

3.25

x~ (in) x ( x (m)
Hatch Velocity

Full Grid 3/4 Grid

IVelocity(mls): -06 -0.1 0.4 0.9 1.4 1.9 2.4 2.9 3.4 3.9 4.4 49 5.4 5.9 6.4 6.9 7.4

VelocIty~m/s): -0.6 -0.1 0.4 0.8 1.3 1.8 2 3.2z 3 4 . I Velocky (s): 40.6 -0.1 0.4 0.8 1.3 1.8 2.3 2.7 3.2 3.7 4.1 4.6 5.1 5.5 6.0 6.5 7.0 7.4|

5.00

Y

I-i 4.75

K)

4.50

4.25

i

% 4.00

3.75

3.50

3.25

5.00i

4.75

4.50

, 4.25 i

>% 4.00 =

3.75

3.50

E

x ()

3.50

x ()
Dome Temperature Full Grid

-11107- I,: 1IS _ X I1

Temperature (C) 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

6 : i," L i : I ', 

TernIcrature 40 45 50 5 60 5 70 I0 85 I 

ITemperature (C): 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120|

5.5

5

5

2 4.5

4.5

As 4

3.5

3

2.5

3.5

3

2.5

4

x (m)

2 3 4

x (m)
Dome Temperature 3/4 Grid

iTemperature(°C): 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120

6 ;i .; ., V I 6 a .ag s . Af.. ......... a

~~~~~~~~ I I~s .xi,.. 

|Temperature(IC): 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115

5.5

$

'I

HA ) .D

5

5

4.5

4.5

'4

3.5

3

2.5

s

4

3.5

3

2.5

i 5

x ()x(m) x (m)
Dome Velocity Full Grid

|Velcity(m/s): -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

- - S <1t

|Velocity(m/s): -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

5.5

H~n

U,

5.5

5

4.5

5

4.5 _

3.5 3.5

3

2.5 2.5

L 4

x (m) x (m)
Dome Velocity 3/4 Grid

Velocity(m/s): -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

6 711 1717 T

|Velocity(m/s): -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 |

5.5

5.5

5

4.5

5

4.5_

4

3.5

3

2.5

3.5

3

2.5

L-.

2 3 4 3 4

x (m) x (m)
Dom'e W-velocit Animation

y~~~~~~~~~~

a__

_ - ii I!

I -     -, I I 11 I 1 1 I KVt,~ : -. " ;I

I-C -I I - , , I
Concluding Remarks

* Multi-block FDS shows great promise in enabling

a user to simulate fires in very large, multicompartment structures.

* Mass flux across grids is well maintained

Xo i* Energy flux across gris is well maintained
.

Verification, Validation and Selected

Applications of the VULCAN and

FUEGO Fire Field Models

Louis A. Gritzo, Ph.D.

Manager

Fire Science and Technology Department

Sandia National Laboratories

Albuquerque, NM

(505) 844-8353

lag=rsandla5gov

www.esc.sandia.gov/firescience.htmI

F,w

Start FY02 Fire Program Profile

FY02 Funding Directly Related to Fire > 6.5 Smililon

Work Type

a m

a c e b n a

O ~a i y i

Hi i

Work Area

2 Rmearch

Cod. Dwlopment

0 cod. VWidaon

0 AppIcdons

_ .. ..;

D-169
IF

Sandia's Fire Science & Technology Program Provides

Solutions to Problems of National Importance

Vulnerability Analyses * Fadliftie, Vehicles (DOE, NRC, DoD)

Fire Suppression Solutions

* Improved use of Les.Ellective Halon Alternative Suppressant._ * Aircraft (LFT&E, Air Force, NAVAIR, FAA. NTSB)

* Ground Vehices (ARMY)

• Ships (NRL, NAVSEA)

* Structure (DOE)

Smoke and Fire Detection and Analysis * Aircraft(Ships (FAA, NAVSEA)

* Nuclear Power (NRC)

Active Memorandum of Understanding (MOU) *_USFS- RMRL, NASA- GRC, NRC. CESTA -

D-170
D-171
PPPE- nis

.wEnclosi Lire Fire Heat Fluxes Characterized

Time = -90. seconds

's.' Ceilin

in ,"4< I.- 18. fttaill

MII.

FlM''

H se 2 (12 Nwel) -Open Dor, Closed Colln Vento

1Ee't x 4uN rPSfa arb r'

Ea"

D-172
D-173
IF - __ ___ __ - __ - 

Integral Validation Experiments Underway in FLAME

Key Set of Fire Data for

FUEGO Validation

* Airflow Control

(<10% variation with

Grid-Scale Resolution

* Temperature Distributions

* Soot Measurements

* TDL Measurements

* Fast-Scanning IR Data

_~~~L

r

V&V Process Overview

Applicatlon Application (Reauty) Phenornena

Simulation Identificatlon

and UQ ed. * | and Ranking

Computational Mathematical

Model Models

Trained & IQE based

Certified Development

Analyst Computer and Verification

Formulation %;Oae N 

---

D-174
Irk 0

PIRT Driven

Minimum Math Model Suite

I

I

I

I

I.

I

I

D-175
p.

SQE and Code Verification Processes In Place

Verification

methodology

testing (&S butmlne level)

*Velflion Pmism Testng

Approaches to Verificaton Problem Testing

Anhlc & seAnia aic SutM

eNurraoal Benwhmak WtOns

Mmlatured Solutios

Test Suite of 17 formal problems

_ 

v ,

I

OFP

Verification Test Suite Coverage

; .. :- . .: - ... , ., _ _ ... '.;:.. A: .,

I

I ~~~~~~~~~~~~~~I U"--

M ._

U . i _

ID C. "

a .

LT IIT

D-176
D-177
NIST Large Fire Facility

George Mulholland, Fire Metrology Group

Leader

David Stroup, Facility Manager

5th meeting of the InternationalSub-panel for Fire

Research

January 24, 2001

Purpose of Large Fire Laboratory

Apply quantified measurements, real-time

analysis, and large area diagnostics diagnostics

to validate models for fire phenomenon

including fire dynamics, detection, and

suppression.

D-179

1
Large Fire Laboratory Exhaust

Capabilities

* Scrubber for removal of

acid gases and baghouse for

removal of particulate

* Variable from 0 to 42 m3/s

* Two Fixed Exhaust Hoods

- 6mx6m,3MW

- 9mxl2m,6MW

* Three Connection Ports

- 0.2 m Diameter

- 0.5 m Diameter

- 0.5 m Diameter

Picture of facility

Current Capabilities, 1/02

* 6 m x 6 m Hood, Heat Release Rate in real time

* Calibration burner up to 6 MW

* 9 m x 12 m Hood - Exhaust Only

* 4 m x 4 m x 2.4 m Burn Enclosure

* Data system developed with near real time

analysis/presentation of results

D-180 2
Current Projects

* CPSC funded Smoke Detector study in

manufactured home

* Fire Research Foundation study of Sub-Lethal

Toxicity including flashover conditions

* STRS funded effort to plan experiments

designed to support WTC fire models and fire

resistance performance prediction

* STRS project to quantify the uncertainty in

heat release rate calorimeter measurements

Quantify Uncertainty in Heat Release Rate

Calorimeter

* Why important: Heat release rate is the single

most important quantity for characterizing the

hazard by a given fuel package.

* Approach:

- Develop real-time data acquisition/analysis

capbility

- Develop calibration burner

- Quantify the uncertainty of the measurement

quantites

D-181

3
Heat Release Equation

Q = ( 2 - X 0 2 )HCpo 2 V

Where Hc is often assumed to be 13.1 kJ/kg and the duct flow,

V, is taken to be equal to the ambient flow.

Complications:

* Hc is affected by CO production.

. V is affected by the change in stoichiometry as oxygen is

consumed and CO, C0 2, and H 20 are produced.

Illustration of Measurement System

Show sampling location, bi-direction probes and TC's,

sampling line, trap, gas analyzers, "He flow system".

D-182

4
Data Acquisition/Analysis/Control Challenges

* Assembled dual processor workstation computer, National

Instruments hardware

*Currently 192 analog input channels, 16 digital I/O

channels

* Developed LabVIEW program for compensating for

different measurement times to achieve near real-time

analysis and display of processed data

-Typical use: 1 second averages for 60 channels scanned at

200 Hz during 1 hour test

* Capable of controlling/measuring calibration burner fuel

flow rate

Calibration Burner/Flow Facility

Show the following components:

* natural gas inlet, shut-off valve,

programmable flow-controller, flow

meter with pulse generator, "heat of

combustion analyzer"

* pilot flame, flow control to various

regions to maintain flame height, burner

dimension, 'fire-eye"

D-183

5
HRR Calibration System

Elements

Natural Gas (daily basis)

Caloric determination of Hc of natural gas

Flow Control

* Safe (industrial control design)

* Accurate (NIST Calibrated)

* Lab View Flow Control & Measurement

Tube Burner

* High turndown Ratio (50 kW-6 MW)

* Design used FDS calculations

FDS Average Flame Height

4 MW Fire in Tube Burner

Calibration Burner, 3 MW

D-184

6
Comparison of the Burner Output Based on

Flowrate to the Heat Release Rate

3000

CalculatedBuner HRRi

-- Calrmetry HRR j

2500 . . . ... .......... ....... ............. r ......

2500

2000 ..-. ___ i 

m! 1500 -. . .. 

0

1000 1500 2000 2500 3000

Time, s

Calibration Burner t2 Burn Designed for a Peak

Heat Release of 2.04 MW

2 0 ....... :.................................. Xe tim Initiated i. .... i ..... ............. ; i .....

2000 .... , ............ ... ,.,.,.. 

1000 .... ... . ........ ............... ........... - .- ............-..-

500 ............ ......... ........ .

0

0 50 100 150 200 250 300 350 400

Time, s

D-185

7
Calibration Burner Range Test

6 MW with 11 Tubes

Two of 11 tubes used to see if

a blowoff condition could be

attained

Close-up of lower section of 1.5 MW natural

gas flame (using 2 tubes). Note low soot level

D-186

8
Calibration Burner Range Test in Large Hood

6000

|-umr out

5000 ... . .. - 1. a'... ..tubes--:- .... 2 tubes 1

4000 ....................-.........- ---- .

3000 .................. ....................... ...................

2000 ....... ............ -..................... . . .

0 .. ... . .. 6 0 ... . 0 

0 200 400 600 Boo 1000

Time, s

Future Capabilities

* Soot volume fraction in upper layer

* Heat transfer measurements in upper layer

* Surface temperature

* Chemical analysislFTIR

* Doorway Flow Measurements

* Water Spray Measurements

* ISO 17025 Testing Laboratory Competence

* Integrated research approach - model used for

designing and interpreting results

D-187

9
Future Large-Scale Capability: Simultaneous

Droplet Velocity and Size

Fluorescing sprinkler spray, Droplet trajectories fluoresced

70 cm by 60 cm measurement by laser sheets

area

D-188

10
#1

Benchmark Analysis # 2

Fire in a Large Hall

Specification for Part I

Stewart Miles

klreand RsEnouerf CeNre, BRE, UK

T 4(9)19# 664924

Fx.: . 0)1923 664910

NST, Gaftherslarg BendM Anab # 2 -Specdjkalionfor Partl 2-3 May 2002

#2

Summary of Benchmark Ex # 2

* To further the findings from exercise # 1:

* comparison with experimental measurements

* fire within a large space - e.g. representative of a turbine hall

* To investigate the influence of modelling assumptions and

approaches

* incorporation of geometrical complexities - non-rectangular buildings - compartmentation

* Part I

* comparison with measurements form fire tests in the VTT test hall - undertaken as part of a EU program

* Part II

* 'hypothetical' simulations for a large fire in a 'real' turbine hall

MIST, c dersbur Bench*Anysis#2 -Specionfor Pan 1 2-3 May 2002

D-189

I
#3 Schedule of Activities

(Pa landilD

* February 2002

* release final specification

* February 2002 - September 2002

* participants to perform simulations

* May 2002 (NIST meeting)

* present preliminary findings for Part I

* further discussion of problem definition for Part It

* Early September 2002

* final results sent to BRE for collation

* October 2002 (BRE meeting)

* present findings for Parts I and II

NiST Gaitersburg Bewwna*Awbd #2 -SpedcfcafionforPan! 2-3 May 2002

#4

VTT Testing Hall

mS2 CW&ztcrsburg Bmdmaw* Anald # 2 -Spedoatkfr a I 2-3 JVay 202 Bwsdaw*Analyrii#2 -Spedflcation for Pan I 2-3 May2002

D-19

2
#5

Internal Geometry and Fire Tests

.. . ,

CnI

1.17m in s4

(- 2MW)

4025

(20h20Un)

no 9Mi. 

CM62

1.8nt I2d0es

(-4MW)

00 ml hn)0.

nom xa. O

(-4 MW)

bo dc0s4( 0.004 Xi)

Muh. _ ,04041 1 3 '1

2 or 3 tests performed for each Case

Heptane fuel - fuel mass loss rate recorded

Thermocouple readings taken

.1S, Gdhersburg BncharkAalysis #2 -Spedficadonfor Pan 1 2-3 May 2002

#6

Derived Upper Layer Temp & Height

Uurteolrtrc St S0

Upper layer height and temperature

derved from thermocouple readings 4' (= | _Tt ~~~~~~~~at three locations (trees)

0 0 20 0 a 0 7 ,0 _ _

Moasured tee0dsrw dt ma 

* / 3 - TK 20

0 ¶0 20 01 40 0 0 70 0

NTGhrwBnr*ny#2SetuofraE-Ty0

MlS, GaIdw8 Bedwi Anlyi 2 -Specdflcadanfr Part 1 2-3 May 202

D-191

3
#7

I

Summary of Tasks

Lumped parameter models to ickchi ZOne CFD taksaappropriate

Hod rof... rate ottire Tw~prale at ttwmnooupia BfM

Tacrerauras at pkumethrmooouples

Up~per ay~rtrepwdur Cr-A,., &i

Intlratkrn flow rate (ore 1 & 0 Irifh floW rate (o* &t2

Mans flow rate Wadtf door I (inS) mam flow rats Irvout door I(M O)

Mans flow rat. In'oul door 2 (inS ) Mms flow at. Wrot door 2 to-wa)

Total hast Wes rate to acd~ bottndedr. Vsotuas at the two doray (sineS

Hsaa lo ftug mook, stm auat Tr*Ml had hea rat to md boundawie

pitsmterrpmore Hog osalth rough meat,. radiut (ma)

lnbodwoe hdWd

LWer a~-tas'nwalura,

( gatofWessoo.4rI.te 0 

Total thow ret..., rate

(Wm t. bwt

MIST Gedrsbarg Bewdmxa, Analysla # 2 -Speftlcadmnfbr Pan 1 2-3 May 2002

D-192

4
 SRS

First Results of COCOSYS and CFX Calculations for

Benchmark Exercise #2 part 1

Fire in a large Hall

Gesellschaft fr Anlagen- und Reaktorslcherhelt (GRS)mbH

hma dnajOaR&fh. Pajt to EOIhAa Rmr Mbdeb

hW Nukw Poww P Appliaro

Qatthesburg, May2 , 2002

W. KIU.n4HolIng, M. eflh (CFX msufts)

1%.MNN..a

Content

* Nodalisation and used models

* Performed calculations and variations

* First results - special aspects

* Conclusions - next steps

D-193
COCOSYS Nodallsatlon

* Side view * Top view

V

COCOSYS Nodallsatlon (cont.)

* 3D view

FIre benchmark 12

COCOSYS no@guan

* Characteristics

- 543 nodes

- 1475 connectIons

- 421 wall structures

L

D-194
COCOSYS Model

* Pyrolysis model

- Use of user-defined pyrolysis rate

- Introduction of a factor for reaction efficiency of 60% above the pool

- Use of a mixing factor of 2.4

- Radiation fraction of 20%o

* Radiation

- Wall-to-wail radiation according specified view factors

- Distribution of radiated heat (from reaction) according specified view

factors from control volumes to wall nodes

- - IW..EEh.-F

COCOSYS Model

* Heat loss through walls

- 1 D-heat conduction model

- Use of correlations for free convection /or specified value

* mitatlons

- No plume model

- No momentun balance

- No soot model

D-195
CFX grid and model

* CFX model

- Use of eddy-break-up combustion

model

- Use of Magnussen-soot model

- Use of k-e turbulence model

- Use of radiation model of CFX

* CFXgrid

Fire Benchmark 2 part I crx W

%.Mom..a

Performed calculations - preliminary results

* COCOSYS

- 3 variations for each case

* full reaction of pyrolyzed heptan (COCul0

* reduce efficiency of reaction at surface to 60o (COCbass)

* change boundary condibns (COCopt

- COCOSYS heat transfer models

- non-adiabatic walls

- move part of inf itration to top of roof

* CFX

- variation of eddy-break-up rate constant (from 23.5 to 19.)

D-196
Preliminary results: Casel

* Tree 1 ower part) * Tree 1 (upper prt)bmIcu

I

.1

COOOSY Fft bwIcrfumk#2cmI

El

14 I I I I

.:M

:. : rly

:"a

I M. 1 94

I I ___,a log !-:::

X. --

0 a M IN 2x no 300

= MI 

Preliminary results: Casel

* Tree 2 (lower part) * Tree 2 (upper part)

coSt nnsumwn a e X coccsrs: mormea Sas

.~ m ' A-_ - s a . S I s a U

-7~~~~~~~~~~~~~~~ o000W

i

D-197
Preliminary results: Casel

I

I

* Tree 2 (ower part)

COCOgSY Fabwf k2 'I

:IU ~ ~~~

r e s _ _ _ _ _ _ _ _

_ a" _ iSS _ ffi :Mc_^

e _ .~~~~aO

I 

I* I I I

!tAr.- I

M ------ t - ---

- - I

I M

I

0. I I- I

- - - - - - -

* Tree 2 (upper part)

COCOSYt Fnt tSSIWUIC2UCNI

. . - 1. - - - -

ft."

e

Preliminary results: Casel

coorn Fre kMMurk 02 CM

* Comparable results for CFX

and COCOSYS (variation

so 1>1 _ _ I _ CO~~0 fulo

E 1 [ .colS _ __ l _ * Less stratification in CFX '30 dMS XtlllJQ_ to ? t X;<>_ meassurement _according 

- 00- _ - } Introduction _ z local

efficiency of 60% leads to

. ] t _ _ l _ ~~~~~good temperatures

0 so I is 20 s 

"O)

D-198
%.I -

Preliminary results: Casel

I W I

9 _ 1 ___ _ 

. . M M = M _ ..

* ,Average' temperatures inside pluMe

* No plume model in COCOSYS

* Temperatures inside CFX

calculations much higher

Preliminary results: Casel

Pme in COOACO YS

Fire Benhmark #2 case I

COCOSYS CakUi1ulo

* Plume in CFX

Fire Benchmark 2 part 1

CMf elculatwn cewel

D-199
V..IMMh..O

Preliminary results: Casel

e Interface height

COCOSYS:t od51otS2 ieI

* Upper layer temperature

COCOSM Fftif.Wffk2 CaM

0~~~~~~ 1'

II. 2 _ _ - I 

II ,_ Oa*

ao 0 IM 10 =D M = M M

-X*

%MEKM

First results: Case 2

* lower part tree 1 * upper part of tree 1

a _.4...;............e. .......... .......--. '-------..-------..------.-------..--..-.............

zip .. nJ.... .... d ; ,+,,, ,+,,,,, j vcilffle~l 

| ° [wn3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~. ... . . . . .

." .. .. .~ ... . .. .. . ..

D-200
G2S

First results: Case 2 (cont.)

* lower part of tree 2 * upper part of tree 2

0COccMtFfl t2 Cklad

12

I. I I

.. . .. . .. ... . ....

CCOcSYMRM b.Iad42CMd

IC - - .. .C U.. ... ..

* 1 t ,

# 0 la M M M M = "

First results: Case 2 (cont.)

* lower part of tree 3

COCalM h bW2CNm

* upper part of tree 3

eC=yt FftbffMU1*dtd

D-201
C=M.

First results: Case 2 (cont.)

* Plume temperatures * Heat loss to wall structures

tocOvt FMit Wdu*U2 CsO c pit "om #2sUc

E~~~~~---- -- 'M,< ......... ...... T ..................... ............. , 

sal ~~~~~~~... ...... ............. ......... .............................. '' '#7 '-'r

io _te NOa N 3 _tr~~~cie- M

~~w -%-)~~~~

_ __~

First results: Case 2 (cont.)

~~~~~~~........

A_....... . .. ^__,.

W~~~

D-202
First results: Case 2 (cont.)

* Height of interface layer

ccc RI au.." Oun

* Upper layer temperature

corn nh C 2 C"

.4 ; ; j i i i i

x

I Vk::---- 1-I 

I .,.

I..

IC - l:a

I

:. -L 'r f I : : I : - D . .. - . . .: . I G a li M = i a a N

_nM

I S 'S ia S a a _

-S.

_.on.

First results: Case 3

* lower part d tree 1

ccovu bnc"Ma an

* upper part of tree 1

C5CDMS~ "bWalkanu3

i' I

I

I

S. S................. ;..

FD27- - --- ~~~~~~...................

..... ..... .... ......... .. ... .. ... ..

S i fi~~~~~~~~~~------------------'........... F---. -j-.'

58A

D-203
INMEMM-0

First results: Case 3 (cont.)

* lower part of tree 2

COMM DWOMM02 CPO

I *C AL ....... ... .... ... . .....

i

W i

upper part of tree 2

COOOSYS FkV bWdWOR02 COW

i ......................

NO. TAB

..........

... ........ ...... -------- ........ ..... ..... ......... ... .... ..........

................. jzl -i ; ; I I

i : : : :

- .. ........ * a 'm IN, NO NO W 5I

First results: Case 3 (cont.)

* Iower part of tree 3 * upper part of tree 3

cocoY*m FnbxrP#w2wIM cocoUMMg-t

.. .I.. . ......

sz . ; , : 4A. >-- ------ --;.-;

Eve ............ ; 4 .......... .....

!""~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.... ............ .........

X~~~~~~~~~~. . . .. ........ .........I 

*_X 101 NO NOa 

D-204
First results: Case 3 (cont.)

* Plume temperature

cocosy Fn D usa.2 en

* Injected/burned heptan mass

(about 70% is bumed)

CCOM n.s.uMS

. i i i i.. i 

# I.LS-_ew~eww*~--v

Io *---- .- 'S---.i-----l/--.

I

I

0 U 0 I i o r s i

First results: Case 3 (cont.)

* Height d inteface layer

aCOWMFtbwiceJWS

... .. .. t... ..... i- . -. .... F.... --. l

.. r ....... XO 

* Upper layer temperature

is

..... t-------- .*-o ......*

|"D~~~~~~. . . . . . i

= : -: - 4- " -

.. _- _ __- . . .

0 d i s D O is a a

_-D

D-205
Comparison between the cases

* Heat release * Temperature (Tree 1 top position)

cocoS F bed~f OOCO#Mfl brWI ~ kN

: f : ' axoses~~~~~ : : : : : : : r sa . aGcgJ . 02:~~~~~~~~ ,* --------- ~~~------ .. .. -

fjj'::j;j' ° s1i---- --- +................................ -- ...... f4o-0 - -- --F -......... -' -- | a ..................... -- -- 

l .= ,............. o,,5,,v

"~~~~~~~~~~~~~~~~. i... ..... - ----t .---- $1 ..;- ;i; ....

, ..... ..... _ .... _ * *

ZIE I

Comparison between the cases (cont.)

* Preliminary CFX results and COCOSYS results with complete reaction

cacOSMs FkI beWMrW1 2 J T.10

- ------------- ~ ~ *-*--4 Y1.I

so ............. A . .~. ... ...

I

I-dmo-p 3-04-Z-OP

T

0 so M ISO M M)

JO SD go 

D-206
Conclusions - next steps

* COCOSYS

- Temperature results

* good results after introducing reactions efficiency of 60% above the

pod

* to strong stratification in the hot gas layer

* no plume model (- temperature behavior TGI, TG2)

- Additional experimental data available?

- Temperature decrease (to check heat loss)

- Concentration measurements

1%.MMM.-F

Conclusions - next steps (cont.)

COCOSYS (cont.)

- Infiltration positioniheat loss to walls

* only small effects on the results

* care have to be taken for the definition of boundary conditions

(environment pressure)

* CFX

- too high temperatures (similarto COCOSYS results with full reaction) - variation of eddy-break-up rate constant

- hot gas layer temperature homogeneous mixed (as measured)

- still some problems with boundary conditions

D-207
- --- - %.Job.--j

Conclusions - next steps (cont.)

* Next steps

- Continue with CFX calculations

- Use of detailed oil burning model in COCOSYS

* some more Initial data is necessary (oil + water mass, geometry)

- Additional tests against other experiments

D-208
I

The Setting

o FP571 performance based design.

o Nine students divided into three

groups.

o Students are typically 2nd semester

post graduate students with

undergraduate degrees in

mechanical or civil engineering.

Am4 rnd t. i , x

D-209

1
Student Subject Background

o Fire dynamics (Drysdale's text).

o Building analysis (primarily code

analysis with an introduction to

performance issues).

o Fire suppression systems.

~~~. i Al S-...1 tiin' FC * Jb Qr~~Ad Liti; 

Work Experience

o Typically one year working for a fire

protection consultancy. Some

students had no experience, one

had over five dealing with shipboard

firesafety

~~~~~~Ace A=~~~~~~~ fI .rV Nv' a

r W t Mid~~~st w ,w ilr. l82

D-210

2
Computer Experience

o Minimal exposure typical for an

engineering undergraduate

o Limited exposure to the use and

concept behind zone models

o Some students had knowledge of

CAD, all had basic windows skills

V7 .5lr t.:mvcrAg;d Uot

Assignment

o Complete part I of benchmark

exercise # 2 "fire in a large hall."

o Duration: 4 weeks (final week for

report writing)

o Tools:

* Jasmine

* FDS

* CFAST

An7, rln v(

E ;# w r y ,,,,ji~~~~Lff7J)*'~hls

D-211

3
Common Issues - CFD

o Tedium in setting up geometry

I Aad Ldi. 

---- . - ------ - - --. 

Common Issues - CFD

o Grid

* Difficulty in matching mesh to the

sloped ceiling, often resulted in

very fine grid just to match

geometry, not needed from a

modeling perspective . Minor but annoying: modeling circular fire with

square/rectangular grid, matching grid oints with thermocouple locatons.

_ -A, wined Lif.

D-212

4
Common Issues - CFD

o Long computation times, especially

with JASMINE

o Lack of time to evaluate sensitivity to

grid - makes results questionable

o Interpretation of results - as there

was no hot layer, how do you report

a hot layer temperature? Even when

there is a hot layer, how do you

determine its location?

W PI L ,X, He ArAd ote.

Issues With CFAST

o Modeling sloped roof

-~~

D-213 5
Jasmine - The Fire

o Equivalent area.

o Default values for Heptane.

o Modified Ultra-fast t-squared fire,

then

o Steady state, finally

o Jasmine default for decay phase.

A.rd Lii.'

Case 1 - HRR v. Time 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

200 A

I . l | i

o s0 100 ISO 200 260 300 30 400 450 500

Ti () J Vv ! -

.ntis i, i

D-214

6
JOSEFINE: Fire Specification

QW

2.

c 05 1.0 1.5 20 25 . 15 X0 5 s0

a-~~~~~~~~~~~~~~~~~~~~~~~~r -0 *1 1

@ 7 P ~~~~~~,, v 

D-215

7
*t'1r / ,nrz.>i~~~l; |

Major Assumptions I ~ ~

o Material

o Fire

o Geometry

o Radiation

o Turbulence

~~~~~~~~~~~~~~~~~~1 sv;,I:. ...->-;

D-216

8
Running the Simulation

o 400 secs/80 hours

o Data saved every 40 secs

o Reached decay phase

9MPI 9t1L0I~ e{rz~w

Part 1 -Expected Model

Output

o Temperatures at 3 Thermocouple

trees

o Temperature at 2 Plume

Thermocouples

o Infiltration flow rate

o Interface Height (reduction of

thermocouple data)

wP I ~AI llt

D-217

9
Part 1 -Expected Model

Output

o Upper Layer Temperature

o Total Heat Release Rate (within

whole hall)

i;:t1|~~~~~~.~ . -.. "--,!i

Height v. Temperature @ 120 s

,~~~~~~~~~~N Tp __, - :

10 E , 51

f 

0 20 40 00

*Tmpwatwre (0) T~~

j Af: '. Bj 

D-218

10
Height v. Temperature @ 240 s ..

1.

ao 40 X

T.P/C)

a0 100 ISO

NA" l.at

Height v. Temperature @ 360 s

10

14

12-

-. 10. Ilo

20 40 so

Tomp (C)

10 100 120

.i I a -- .i-

?}a A.4 :..:;ur ..,'t IIJ I -",

v _.,I I ,o s ,

D-219

11
Time v. Temp Above Fire _

IC

.00

0

40

822

- CO

MCO

0

0 N so 120 1do 2M

M1-.

220 no 380 do A0

rI"-"www awffD-Mlil *L21R0'ft,

Sample Profile

a Ilac IeI. -As- 

_ F I :t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~d Llis.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

D-220 12
Interface Height v. Time

12C0 14 A1gW~jt 

t~oo

0 40 so 120 ISO 2 0 240 260 320 #0 400 440

Tno () 

t-o- rXv -wpstt 1w 

D-221 13
Conclusion (JASMINE) -

According to the Students

o Results appear reasonable

(assumptions)

o Fire Modeling can be dangerous

CFAST

o Geometry

o The Fire

o Interpretation of results

@ ; i~~~~w- : :- siv i

D-222

14
CFAST - Geometry

o Conserving the volume of the

sloped ceiling,

o Conserving the surface area of the

sloped ceiling.

o No significant difference in results:

Use rectangular parallelogram with

15.8 m ceiling height (vs actual peak

height of 19 m)

Three Cases

o Case 1 uses a pool fire of radius

1.17 meters, assumes the doors are

closed, assumes no mechanical

exhaust, and uses natural room

leakage in the form of four small

vents.

D-223

15
Three Cases

o Case 2 assumes a pool fire of radius

1.6 meters, doors closed, no

mechanical exhaust, and natural

leakage.

o Case 3 assumes a pool fire of radius

1.6 meters, doors open (0.8 m x 4

m), mechanical exhaust on, and no

natural leakage.

A i m~~~~~A i....zllr;xs aEwry-M;t,t~t Silat

Problem

o Couldn't model mechanical

exhaust...used natural exhaust

WI'1~ I' ~ 'A ^ Al Lb.:. -f 

D-224

16
HRR for Each Case

4.OOE+06 ~~~~~~Case 

3.50E0t6E2 X:C;gase 3

2.50E+06

C2OOE+06 R 

1.00Eo.06

5.006E.05

O OOE+0 0 m

0 100 200 300 400 500 600

Time (see)

*- WlI .

Upper Layer Temperature

- --*-~~Case,-

140 -Cse

120 Case 

100 tI

80 

C.

J5 60

40

20

0

1

2

3

0 100 200 300 400 500 600

Tlme (8ec)

s,4uLi ~ ;;!uOr, 

D-225

17
CFAST - Summary

o Results only as good as zone model

approximation

o Thermocouple predictions limited to

layer temperatures

FDS Results Imilar issuestoJASMIN

o Similar issues to JASMINE

w wrl A X i i~~~Ul. lC,..

D-226

18
Overall

o All models created problems for

users

o Users highly frustrated with

software

o CFAST easiest to use, and therefore

sensitivity studies conducted

Acknowledgments - Students

oJason Cardinal

o Garrett Kaye

o Scott Kelly

o Matthew Klaus

o Jonathan Rich

o Jim Shannon

o Lars Sorthe

o Toby White

o Nick Williams

s W E'I "'' .'- ' '; - he s '; 

D-227

19
_______ Misusing

The University of I

Science and Technology. ing And Life.,

Fire Models

au Jonathan Barnett

94 Center For Firesafety

Studies

Worcester, MA 01609

The Setting

o FP571 performance based design.

o Nine students divided into three

groups.

o Students are typically 2nd semester

post graduate students with

undergraduate degrees in

mechanical or civil engineering.

A........~And;.. 4E,....

D-229

1
Student Subject Background

o Fire dynamics (Drysdale's text).

o Building analysis (primarily code

analysis with an introduction to

performance issues).

o Fire suppression systems.

T';.;11W.'X~T!

Work Experience

o Typically one year working for a fire

protection consultancy. Some

students had no experience, one

had over five dealing with shipboard

firesafety

'W MUwry .; Fi. ','ii',,'''''l''

D-230

2
Computer Experience

o Minimal exposure typical for an

engineering undergraduate

o Limited exposure to the use and

concept behind zone models

o Some students had knowledge of

CAD, all had basic windows skills

wWP-L;

Assignment

o Complete part I of benchmark

exercise # 2 "fire in a large hall."

o Duration: 4 weeks (final week for

report writing)

o Tools:

* Jasmine

* FDS

* CFAST

MN.,.,-;,....,

D-231

3
Common Issues - CFD

o Tedium in setting up geometry

@E MS-. ";' Iin rel I 1 'I 

Common Issues - CFD

o Grid

* Difficulty in matching mesh to the

sloped ceiling, often resulted in

very fine grid just to match

geometry, not needed from a

modeling perspective

* Minor but annoying: modeling circular fire with

square/rectangular grid, matching grid points with thermocouple locations.

D-232

4
Common Issues - CFD

o Long computation times, especially

with JASMINE

o Lack of time to evaluate sensitivity to

grid - makes results questionable

o Interpretation of results - as there

was no hot layer, how do you report

a hot layer temperature? Even when

there is a hot layer, how do you

determine its location?

SWN PI''

Issues With CFAST

o Modeling sloped roof

iWPI tf;t

D-233

5
Jasmine - The Fire

o Equivalent area.

o Default values for Heptane.

O Modified Ultra-fast t-squared fire,

then

o Steady state, finally

o Jasmine default for decay phase.

SwPI A;:i:Jl_

Case 1 - HRR v. Time

120

16ao

1400

200

0

00 25 300 3-0 400 450 500

T () W I

D-234 6
JOSEFINE: Fire Specification

__ ~~~~~~~~~20- 

in~~~~~~~~~~~~~~~.6- 

ao U . 15 20 as so as 4.o ts sol

1£11£1-1~~~~~~~~~~~1 

, . n I 

.j .. ^. ^ -. ~~~~~~~~~~~~S 'id 

F i~ i , . .

r1,; '

D-235 7
-I . .

PIKAw tI.,

Major Assumptions

o Material

o Fire

o Geometry

o Radiation

o Turbulence

w w r l S~~~~~,;,llJ,,, it'. lre i

D-236 8
Running the Simulation

o 400 secs/80 hours

o Data saved every 40 secs

o Reached decay phase

SEE .. 1 .-. : t t

Part 1 -Expected Model

Output

o Temperatures at 3 Thermocouple

trees

o Temperature at 2 Plume

Thermocouples

o Infiltration flow rate

o Interface Height (reduction of

thermocouple data)

9

D-237
Part 1 -Expected Model

Output

o Upper Layer Temperature

o Total Heat Release Rate (within

whole hall)

\."t~~!:.{ 1 l.,

Height v. Temperature @ 120 s

9

I

=T1 -12I _-M

I z I ;~'~ ~j~ ~~jCUTREOUINR 20 ~~ ~~~40 60

Tempe~stur (I : i;:,.

D-238 10
Height v. Temperature @ 240 s -

is

is

12

rI0

1T2

-73

20 40 U0 U 10 12D

TsqP(C) *. . .

Height v. Temperature @ 360 s

14

12

10

0 20 40 so 40 1_0 120

P00~ ~~~ ~~~~I :m And if2gX_2Ewt0i.;, O 20 40 tO eo 1co 12C~~~~(0 T ~PtC ,x,, ,.... 

D-239

11
Time v. Temp Above Fire

n. ()

I - w - @ w I Si~~~~~~~~~~~~~~~~~~~~... -,;"; i'..,',.:

Sample Profile

I~~~~~~~ I. - t ,

Ts * .~~~~AA -ii,.

D-240

12
Interface Height v. Time

ow

40 so 12D 14D 240 240 240 0 3w 40 04 440

_ X W Tm I' D(s) a -::~~~~~~~~~~

Upper Layer Temp v. Time

"me (.)

no M~as 4W

W wri~m~-

D-241 13
Conclusion (JASMINE) -

According to the Students

o Results appear reasonable

(assumptions)

o Fire Modeling can be dangerous

"uiXVP ^ . .::- . Iii:^>rs \ l' _ _ _ w W ~ ~~~~~~~~~~~~~~~~~~. , i,;;. i °-sf

CFAST

o Geometry

o The Fire

o Interpretation of results

H W PI i A~i'.;

D-242 14
CFAST - Geometry

o Conserving the volume of the

sloped ceiling,

o Conserving the surface area of the

sloped ceiling.

o No significant difference in results:

Use rectangular parallelogram with

15.8 m ceiling height (vs actual peak

height of 19 m)

O.' Il.i...1).',..

Three Cases

o Case 1 uses a pool fire of radius

1.17 meters, assumes the doors are

closed, assumes no mechanical

exhaust, and uses natural room

leakage in the form of four small

vents.

Ywft15 D-243
Three Cases

o Case 2 assumes a pool fire of radius

1.6 meters, doors closed, no

mechanical exhaust, and natural

leakage.

o Case 3 assumes a pool fire of radius

1.6 meters, doors open (0.8 m x 4

m), mechanical exhaust on, and no

natural leakage.

Problem

o Couldn't model mechanical

exhaust...used natural exhaust

B i t 't~~~~~~~~. I....;..

16

D-244
HRR for Each Case

+Case 1

4005.06 Case 2

3.5015+06-

200OE.06

2.150E.06 2.0015+;06 

1505.05 1 ... ,OOE106 0 iq'i .t0J X tF

5oOOE05; ,Shat~snsl

0 005.00 I

0 100 200 300 400 500 600

Time (sec)

a' fflRi'

Upper Layer Temperature

--.- Case 1

140 X = Case 2

60° 

140

201

0 100 200 300 400 500 600

Time (sec)

~______________ _ .';,:.:,.:

D-245 17
CFAST - Summary

o Results only as good as zone model

approximation

o Thermocouple predictions limited to

layer temperatures

DI V O T~~~ ;|:: isi;-1l w w ry ,\;,,;aJ,,,,]|~~~~~~~~~~.. 1 1 |'{

FDS Results

o Similar issues to JASMINE

w w , *.: ,,....,,,,-,,., ,1,Ir'! ...... w w v v ~~~~~~~.%.,,1 il'.

D-246 18
Overall

o All models created problems for

users

o Users highly frustrated with

software

o CFAST easiest to use, and therefore

sensitivity studies conducted

Acknowledgments - Students

o Jason Cardinal

o Garrett Kaye

o Scott Kelly

o Matthew Klaus

o Jonathan Rich

oJim Shannon

o Lars Sorthe

o Toby White

o Nick Williams

W~~~~~~~~~~ 7 i;, f , 

D-247 19
Analysis of Benchmark Exercise Two:

An Examination of Large Turbine Hall Fires with the

CFAST Fire Modeling Code

A. R. Martin and D. A. Coutts

amber.martin@wxsms.com

a Ho_&*W-.w Westinghouse Safety Management Solutions

SRS Perspective

D SRS has an obligation to fulfill DOE expectations

D DOE Fire Safety Program

". . . the use of such models is predicated on their

being conservative and validated."

D Defense Nuclear Facilities Safety Board

"Given the prominent role played by computer codes in ensuring

the safe operation of DOE facilities, it is imperative that a thorough

and effective approach to guaranteeing their quality be

implemented." ITECH-25]

Westinghouse Safety Msnagement Solutions

2

D-249

1
w WO aoe

-.~i SRS Focus

> Demonstrate code capabilities

> Understand code limitations

> Establish sample problems

> Ensure consistent analytical approach

> Document V & V efforts

Westinghouse Safety Managemvent Solutions

3

Turbine Hall Geometry

Westinghouse Safety Management Solutions

4

D-250 2
Approach

> CFAST Version 3.1.6

> Adjusted ceiling height to maintain constant volume

> Lower Oxygen Limit - 12%

> Radiative Fraction - 20%

> Relative Humidity - 50%

> Wall Layers?

Westinghouse Safely Management Solutions

5

Summary of Cases

Pyrolysis Rates for Part 1

Case case 2 Case 3

t dt/d t: dmfddndt

(n-dn) (kgts) (min) (kgts) (min) (kgts)

0.0 0.0 0.0 0.0 0.0 0.0

0.22 0.033 0.23 0.057 0.22 0.064

1.5 0.045 0.5 0.067 1.05 0.084

4.8 0.049 1.52 0.081 2.77 0.095

5.45 0.047 3.22 0.086 4.27 0.096

6.82 0.036 4.7 0.083 4.87 0.091

7.3 0.0 5.67 0.072 5.5 0.07

6.2 0.06 5.75 0.0

6.58 0.0

Ventilation Conditions for Part 1

Case I Case 2 Case 3

doors closed doors closed doors open (0.8 m x 4m) no mech. exhaust no mech. exhaust mech. exhaust (11 m3

I/s)

natural leakage natural leakage ignore natural leakage

Westinghouse Safety Management Solutions

6

D-251 3
R

Heat Release Rate

4

la

60 120 180 240 300 360 420 480

time (seconds)

Westinghouse Saety MAenagement Solutions

7

Interface Height

LI

E

0 60 120 180 240 300 360 420 480

time (seconds)

Westinghouse Safety Management Solutions

8

D-252 4
-was

Upper Layer Temperature

500

400 Cf M 

300

200

100

0 60 120 180 240 300 360 420 480

time (seconds)

Westinghouse Safety Managent Soiutlona

9

Ws*_

Infiltration Flow Rate (Cases I & H)

S

6-

Case II

2

0 60 120 180 240 300 360 420 480

time (seconds)

Westinghouse Safety Management Solutions

10

D-253 5
Door Flow Rate (Case III)

20

15 

i~~~~~~~~~~~~~~n

5

0 60 120 180 240 300 360

time (seconds)

Westinghouse Safety Management Solutions

11

Mechanical Exhaust Flow Rate (Case II)

12

4

0 60 120 180 240 300 360

time (seconds)

Westinghouse Safety Management Solutions

12

D-254

6
OConclusions

> Demonstrate code capabilities

> Understand code limitations

> Establish sample problems

> Ensure consistent analytical approach

> Document V & V efforts

Westinghouse Safety Management Solutions

13

D-255

7
HADCRT Results for Benchmark Exercise #2

May 3, 2002

Presented to the:

International Collaborative Project to Evaluate Fire Models

for Nuclear Power Plant Applications

Presented by:

Boro Malinovic and Martin G. Plys

Fauske and Associates, Inc.

16W070 West 83rd Street

Burr Ridge, IL 60521

Background

* Nuclear fuel cycle facility source term analysis

code, HADCRT (Hanford Double Contained

Receiver Tanks).

* Logical to extend HADCRT explosion &

accident capability by adding fire models to the

validated baseline code.

May 3, 2001 Fauske and Associates, Inc. 5th 2

Meeting at NIST

D-257

1
Background

* Generic features:

- Arbitrary topology

- Arbitrary specification of chemical species & properties

- Fog formation (vapor/aerosol equilibrium)

- Density-driven counter-current gas flows between

compartments

- Aerosol agglomeration, settling, transport, & source models

- Radiation networks

- Multi-dimensional heat conduction

May 3, 2001 Fauske and Associates, Inc. 5th 3

Meeting at NIST

Background

* Fire features include:

- Stratified layer composition and thickness per

compartment

- Pilot fire definitions (burn rates, yields, etc.)

- Plume model

May 3, 2001 Fauske and Associates, Inc. 5th 4

Meeting at NIST

D-258 2
HADCRT Fire Model Features

Receiver *1

Smoky Layer

Wali

Duct

4+

Source Room

Smoky Layer

I Cable Wall

Tray I

Receiver #2

Smoky Layer

I

I'. * 1 -4fif2'~7!U "I-- , 8 J. :.w." 'G '*"' ' I l E

Door Vented

Equiment

M*WO4MCDR 3-1 A

May 3, 2001 F

IOr

Pilot Fire

and Plume

Fauske and Associates, Inc. 5i 5

Meeting at NIST

HADCRT Model for Benchmark Exercise #2

* Two regions: hal and the environment

- Hall: 5891 W3 , 378 m2 floor area, 1800 m2 wall HX area,

parallelepiped, 22 C, 101350 Pa

- Environment: 20 C, 101350 Pa

* Seven Heat Sinks

- Floor 1 ft thick concrete; adiabatic on the outside

- Sheet metal is neglected

- Walls and ceiling are 5 cm mineral wool

- One HS for floor, six for walls

- Wall HS model the wall as six panels

- Material properties from Table 1 of the problem specification

May 3, 2001 Fauske and Associates, Inc. 5th 6

Meeting at NIST

D-259 3
HADCRT Model for Benchmark Exercise #2

* Junctions: depends on the case

- Case 1: Four junctions, as shown in Table 2 of the problem

specification, but only "z" coordinate matters

- Case 2: Same as Case 1

- Case 3: Two doors, one top junction has 11 m3 /s forced flow

* Code inputs for fires: region, area, burn flux, fuel

properties, start time, fuel mass, yields for CO, C02,

CH, soot, H20; limit of five fires

* Use handbook values for heptane; e.g., 44.6 MJ/kg

* As a first cut, skip radiation; fire is 100% convective

May 3, 2001 Fauske and Associates, Inc. 5th 7

Meeting at NIST

Case 1 Gas Temperatures

90

* 72.1

80 24

70 - T2

c~ 0 60 12 8 20 30 6.20 40 54 0

_~~~~~~r 6

60 7,~~K 2.

1!50 2

a 72.9

i~40

T *2.10

30 - o-mk

- -- -- -- - - -Smoky

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauake and Associatea, Inc. 5th 8

Meeting at NIST

D-260

4
Case 1 Interface Height

* Interface #1 * Interface #2 -Srnoky Layer: |

16

E 14

010

.0 8

6 -

2

0 60 120 180 240 300 360 420 480 540 600

Tine, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 9

Meeting at NIST

Case 1 Flowrates

- Soaom# - -Top #1 - oom #2 - -r Top .

2.5 .- _. .- -.

2.5

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 10

Meeting at NIST

D-261 5s
Case 1 Heat Losses to Floor/Walls

450000 . _ _ . . . _. -

400000 l

350000-

* 300000-

- 250000

200000/

* 150000 /

100000

50000

0 60 120 160 240 300 360 420 480 540 600

Time, seconds

May 3,2001 auske and Associates, Inc. 5th 

Meeting at NIST

Case 2 Gas Temperatures

140

* 2.1

120 2.4

1 0X. .G1

40 -2/ * , _ * I2o6

6 a ~~~~~~~~~~~~~~~~~~~~1~~~2.7

S ~~~~~~~~~~~~~~~~~~~~~~~~T2.8

60 T~~~~~~~~~~~~~~~~~~~~ 2.9

*T2.10

40 --- 

. . .... ....- . ... Smokcy

20

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 12

Meeting at NIST

D-262 6 .
Case 2 Interface Height

-Smoky Layer * Interface Ht. #1 a Interface H-t. #2

18 _

16

E 14 

212

10

8

14 

2

0 

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 13

Meeting at NIST

Case 2 Flowrates

-Bottom#1 -- Top #1 -Bottom 2 -- To #2

5-

'S 2.5- 

0

S-2.5 - \

} *~~~1 and 2 Fwlas coincide; rlows a f same in identical 40ions

-5-

0 60 120 180 240 300 360 420 480 .540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 14

Meeting at NIST

D-263 7
Case 2 Heat Losses to Floor/Walls

800000 -__ __

700000 -l

600000

500000

,,40D00 - \

X300000- 

200000

100000 200

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates. Inc. 5th 15

Meeting at NIST

Case 3 Gas Temparatures

1

e

E

z

a

E

S!

40 -

20 _'

00- / .2

80- ./

60 - . 1

40 - / S

20 . . .. . . . . . .. . . . . . .. . . . . . .. . . . . . .

* 72.1

T2.4

x T2Z

* 72.6

. 72.7

.12.8

- T29

* T2.10

-S . NokySmoky

- Sffo

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

2001 Fauske and Associates, Inc. 5th

Meeting at NIST

May 3,,

D-264 8
Case 3 Interface Height

I -Smky Layer * Interlace H. #1 a Interface Ht. #2 1

0 12

2

10

o

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates. Inc. 5th 17

Meeting at NIST

Case 3 Flowrates

-Door#1 -Door#2 - -Verabon

12.5 

_ 10

7.6S 

* 5

t 2.S

.Y\ Flow throuh each door is identrcal

-2.5 

¢ -S-5

.7.S-\5 

-10

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 18

Meeting at NIST

D-265 9
Case 3 Heat Losses to Floor/Walls

800000 -

700000

600000

500000

i 400000-

300000-

200000 -

0

0 60 120 180 240 300 360 420 480 540 600

Time, seconds

May 3, 2001 Fauske and Associates, Inc. 5th 19

Meeting at NIST

Results Summary

* Non-smoky layer temperatures are low

- Radiation neglected

- Problem specification for junctions creates a chimney effect

that brings cold air into the non-smoky layer

* Junction specification creates no pressure differential

between the hall and the environment

* Parametric studies for leakage areas and infiltration

are desirable

* Smoky layer temperatures are in good agreement

- need to include the 80/20 split between convection and

radiation and consider absorptivity

May 3, 2001 Fauske and Associates, Inc. 5th 20

Meeting at NIST

D-266

10
Future Work

* Parametric studies of leakage and infiltration

* Radiative aspects of the problem; set up radiation

networks to better model gas and heat sink

temperatures in the non-smoky layer, and target

temperatures

* Smoky layer absorptivity

* Report plume temperatures

* Volume vs. height relationships for regions

May 3, 2001 Fauske and Associates, Inc. 5th 21

Meeting at NIST

D-267 11
Kevin McGrattan

Building and Fire

National Ifistftuie

D-269

I
D-270 2
1.1 T1.5 2

so n. ISO 90 ri0IS

80 14 10 __ 70 n1 080

l o go

20~~~~~~~~~~~~~~~~~~~~8

to 10~~~~~~~~~~~~~~~~~~4

0~~~~~~~~~~~~~~~~~~4

0a 50 100 130 200 250 500 350 400 450 500 550 00

TIME (a)

SWC

140 T2..TI.lO la

280 120 n1. 240

' 10.820 La -t- 2.3 200 L

wo . Riz 

0 I0820 

20~ so

5 so 100 150 200 250 300 350 400 45O 500 550 oo

TIME (a)

D-271 3
- ~~~~~~~~~

-~~~~~~~~

- ~~~~~~~ 0I - z~~~~~~~~~~~

.. . . . . . . 3w~~~10

140

20

o

W 40

20

T2.1 -T2.3

mli

-..i:

125 77. a -

280

250

240

220 E

200 U

180

140 U

120 2 soE

40600

40

50 100 150 200 250 300 50 400 450 500 5 

TIME (a)

0

in

816

R 140

120

10X

aI 40

20

T2.G-T2.10

15.5

T2.3

. 1z

- ... ... ... ... .. ... ..I .. .. .I .. ...... . 200

O. '_'_ '' '' :' ' '' . ' '~~~~~~~~ 0 50 100 l50

300 

250 m

soo

200 250 300 20 400 450 0 N0 *00

TIME ()

D-272

4
D-273

5
_ ~~~~~~~~~~~~~~~~~~#1

Benchmark Analysis # 2

Fire in a Large Hall

Preliminary CFAST and JASMINE Simulations for Part I

Stewart Miles

R;> and&RtsEngyweering CeNre, DRE, UK

Tse: .4)*A l923Pe224

NICE Ckterbw~r Decdio*Anlysis#2 -Prdijbay Snofior Par 1 2-3 May2002

U

#2

Summary of Simulations

* Cases 1, 2 and 3 investigated

* CFAST/FAST version 3.1.6

* predictions of upper layer temperature and layer height

* investigation into implementation of geometry (complex roof)

* investigation into boundary (conduction) heat losses

* investigation into restricted ventilation openings (cases 1 & 2)

* JASMINE (CFD) version 3.2.1

* comparison with temperature profiles at thermocouple trees 1,2 & 3

* investigation into boundary (conduction) heat losses

* investigation into restricted ventilation openings (cases 1 & 2)

* grid refinement study

nsr. G oest Betzckma Analysis#2 -Prarhwey SinadadowforPar I 2-3 Afire 2002 N7h7 OaUhersbw2-3 May2002

D--275

I
#3

CFAST Simulations - Cases 1&2

* Baseline simulations (following problem specification)

* 2 horizontal flow vents (1.414 x 0.707 m) at floor level and 12 m

* 'equivalent flat ceiling' height = 15.84 m

* heptane fire source

- AH,44.6x1O6 J kg' - pyrolysis rate as specified

- radiative fraction = 0.2 - hydrogen to carbon ratio = 0.19

* two-layer solid material at walls and ceiling (steel and mineral wool)

* Variant simulations

* steel only and mineral wool only solid material at walls and ceiling

* adiabatic boundaries

* single horizontal flow vent (8 x 4 m) at floor level (e.g. two 4 x 4 m doors)

* 2 horizontal flow vents (0.2 x 0.1 m) at floor level and 12 m

* 'equivalent flat ceiling' height = 13 m and 18 m

* upper vent at 6 m and 14 m

NIST, GWihersburg Benay Ana4tfis#2 -Peb SkurStim for Part! 2-3 May 2002

#4

CFAST Simulations - Case 3

* Baseline simulations (following problem specification)

* 1 horizontal flow vent (1.6 x 4 m) at floor level (two 0.8 x 4 m openings)

* 'equivalent flat ceiling' height = 15.84 m

* heptane fire source

- A>44.6x106 J kg' - pyrolysis rate as specified

- radiative fraction = 0.2 - hydrogen to carbon ratio = 0.19

* two-layer solid material at walls and ceiling (steel and mineral wool)

* 11 m3 s extraction flow rate through HVAC vent at 10 m height

* Variant simulations

* 'equivalent flat ceiling' height = 13 m and 18 m

* HVAC vent at 8 m height

NMST GaiuhrbWvrg &c/markAaalysUs# 2 -PreluniarySimudopcforPan 1 2-3 May 2002

D-276 2
CFAST Analysis - Case 1

CFAST: Ptt I- cs 

Findings:

2. ^ upper layer temperature sensitive to

w d" .. conduction heat loss mechanism AS, |.<. a, 4mx~md _ (but onlyafter2 minutes) .436x4fl1

o a 1 1io 2-0 3W 4 4 upper layer temperature not

Thkm (9) sensitive to size of 'restricted

ventilation openings'.

UAS: Pu I -cam layer height not sensitive to

1: ^ Ewconduction heat loss mechanism

I2 4Sw eNly O< layer height sensitive to size of

i IO^ . _- Wd -oY 'restricted ventilation openings' (but

a e -m~do only after 4minutes)

4 .-* .o.1m 4 xo.m w

0 e0 0 I 0 2W S 340 40 40

MIST. (Cwrskrg Baoxhoark Analysis#2 -Prel oaryS wl auornsfor Part 1 2-3 May 2002

U #0

CFAST Analysis - Case 1

CFST: Pl-ci 1

140 _

1 20 A a"t

I eo,0 -_13mOMcomphw

. *0 A A A 180 ophd

a .. . prWO--b stem

20 > .. tqm.rwfat14m

0 f0 120 1 40 30 30 420 40

7fth1)

CFAOT: Pwt I -c 1

20 -

Is

t'4 , *^ W

10 ~A 13r O - -h1W rm

o A a A . A A

0 6 O 1 24 O6 420 40

Thio (a)

Findings:

location (height) of upper 'restricted

ventilation openings' not significant

upper layer temperature sensitive to

height of 'equivalent flat ceiling'

layer height sensitive to height of

'equivalent flat ceiling' only for first

60 seconds

NIST, Gaers" BRmvoar*Analysis 2 -Preftmoy Siondadonw for Par 2.3 May 2002

D-277 3
_ ~~~~~~~~~~~~~~~~~#7

CFAST Analysis - Case 1

CFAST: Part I - I significant over-pressure with the

____________ very small openings

O } pressure - ambient for other opening

410 M > | -o @ .4m x 4n dOW sizes

.10.0 -O.mO.lm_0o

NIST, Gdarkrabw Bex/mf* wAn* y#2 - fteUimay S daa for ParI 2-3 AQzy 2002

CFAST Analysis - Case 2

CFAST: Pat I -cm 2

140 _ Findings:

1,0 UOA_ | EV upper layer temperture not

EO £: A -4mx4mdw sensitive to size of 'restricted A ao g K. I o.,M.Qm ventilation openings'

0 ~ 421 -r layer height sensitive to size of

T10 2 4) 'restricted ventilation openings' (but

only after 3 minutes)

OFAST: Pafl I -c 2

J2 , 12 AAABO < ~~~~~~~~-4m x4mn door

X ^ ~~~~~~~~01mxO.Im_"f 4 

0 * 10 Io 3oJ10 480

N= Gahersbg Bnchmark Abjfs # 2 -Pfelhnbwy Sd ardu for Pan 2-3 MW 202

D-2 78 4
#9

CFAST Analysis - Case 2

CFAST: PwtI -c 2

____ Findings:

120 *-A .t upper layer temperature sensitive to

2D / layer height sensitive to height of

0 'equivalent flat ceiling' only for first

O 00 1Z1 IN0 20 iMO 9M 4 400 60 seconds

CART: Part I cme 2

20 -

14 *Wt

6 00 120 160 240 O 3 420 40

Thlw(s)

N7ST GaMersburg &,whmarckAniys#2 -Prteimbnary Su wfor Part1 2-3 May 2002

#10

CFAST Analysis - Case 3

CFAST: Pu 1- -e 3

14D ___ _ Findings:

1 ~~~~~~~~~A EO

12D A location (height) of HVAC vent not & ^ SD % "^ -13Mar * significant (within range

6 s0 A' A 1201~ . 1investigated) } 2°0 /2 .~~~~~~~~... ... we aZa

0

o. ___.__.__.__._.__.__.__. upper layer temperature sensitive to O 60 120 16O <0 t 4D height of 'equivalent flat ceiling'

layer height sensitive to height of

CFAST: Pet I - c. 3 'equivalent flat ceiling' only for first

20 _ _ _ 60 seconds

f 12 0 =13m 

A A - Irn cam hi'#4 : st - -1011cmllDhW

24 .... ,dl Mt M

2

4o6 e 0 160 240 XD 3 420 460

th (a)

MIS, Gd*hersbur &ondww Analysis # 2 - Prelamnwuy Sildiowfor Part 1 2-3 Ay 2002

D-279 5
0 CFAST Analysis - Case 3

CFAST: Part I -ce 3

]'-o

I :~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.1 -4 a a - p2

.7 _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ .I__ 

TWO (a)

NLST aafthersbhwg Bnmau*A~uziysiu#2? -Preilmwy Shi~wa11onforPart 1 2-3 May 2002

_ ~~~~~~~~~~~~~~~~~~#12 E JASMINE Simulations - Cases 1&2

RANS with standard ic-e turbulence model Numerical timestep = ls

Eddy break-up combustion model with heptane ( S=O 8 s 44.6x106 J kg1)

Six-flux radiation model (& Ihelove's emissive power model)

Convection (h= 10 I s nr2 K-1) and radiation heat losses to solid bcundaries

Semi-infinite approximation for conduction at boundaries (time-dependent conduction depth) -sted ignored

Ventilation options investigated:

_S n

2 square

0.072 x 6.9 m sb

_sliply peos cm& west walls

Boundary healt losses investigated:

con_ a mod

AWS7 Ga*ersbwT &_awrkAnatyss 2 -Preltimbswy Simuladausar Part 2-S May 2002

6 D-280
U JASMINE Simulations - Case 3

RANS with standard ic-e tuibulence model Numerical time-step, = Is

Eddy break-up combustion model with heptane (AHk=O.8 x 44.6x106 J kg')

Six-flux radiation model (& Thelove's eziLissve power model)

Convection (h,=10 I s in- 2 K-) and radiation heat losses to solid boundares

Semni-infinite approximation for conduction at boundaries (time-dependent conduction depth) -sted ignored

#13

Boundary heat losses investigated:

conlodvity modified

Mesh refinement investigated

.,(C) T I 

'I -''0

NIS, Gthersburg ,eSmr Analys 2 -Preimbwry Siudation fbr Pa I 2-3 May 202

- ~JASMINE Temperatures for Case 1 #4

~~- - ~

I 

!11X ,tfc) 

a* Anabsi ,-

NlST, Gakhersburg DadmadAnlsis #2 - lefinmbary Simumatiosj fr Pa rt I 2-3 May 2002

D-281 7
_ ~~~~~~~~~~~~~~~~~~~~#15

JASMINE Temperatures for Case 3

~~~~~~~~~~~~~~~~~~~T:C Go(CI

| * T ma |T (a

NIST. Gaersburg Bencmaw* Anatysk #2 -Prefimbsty Sbulaufor Par 1 2-3 May 2002

a CFD Mesh Refinement

Predictions of temperature for case 3 at 60s

X., X

- 136 500 eements

C t .

#16

- I 100 000 emeats

(X2 in each direCdon)

NIST. Gacrsbrg BehniamAnalysis#2 - PrelDnav Shn dlmufor Part I 2-3 May 2002

D-282 8
#17

JASMINE Analysis - Case _ _1__ 

4A8U1 ftgl -Tusg *5U Pt ~1.Tm t 17

12 ft 3~~~~~~~~~~~~~~~~~~~~~wf

1t ___ j____. ____- /

0. ,. }" * "

O la 40 nso o o 70 f6 w 1;0 la o s7 va M a 0 M xo 0 V* o 1 

16 AK~~~~~~~~~~~~T".6f

ISAA6A J At -163124 It rt' l-T2

-ow i If I ~~~~~~ - . -~~~~~~~0-I,,

o6 o 7 . 1 - ' ' 6 4 ........ -'

10 MO t 40 0 0 0 I'D cO o Olo o o MD a o 0 *o3 so Mo7 M

Smoke layer temperature sesitive to conduton heat loss mrhanism (ut layer height i less so)

Nanow slot openings give same results as se openings

Porous walls resicted ventilatIon' reducea s an

NISI, Gavuherbs BakmawAwnay -Prelbsbiaiys dasiowfor P1 2-3 May 2002

JASMINE Analysis - Case 1

tAM Pat I -Tm.o I a 2W MWW Put I-Tree 2 d2404

4 4~~~~~~~~R iA1

OD v 50 Pu -M; a 404 11UID ul Pam a~m am air

- - '- - - 14

MT a[*rbj B~m*r~ss0 PU IaySt~dfr at 23My20

D-283 9
_ #~~~~~~~~~~~~~~~~~~~19 U1Eg JASMINE Analysis - Case I

JMz1UPut -Ppaae ME IPlphml2

t. _ - So _ _ _ __.t vngki~~~~~~~~~~~~~~~~~~~~~~Prt lalk

: ~~~~~~~~~~~~~~~~~~~~~~~, lt '

o . . . . . . . . . . . u... ....... m 0 o X tw oM m o 101C0 tom am

:M~ hn I. Rspdmmt24kJ N:t Put I.P.pmma 4

7_t:X ~ .. , ~ * d"

Conducton heat loss mechaism has less prowunoed influence on pume tempmalme

N1_Gaihersburg Bdnckw*A Y#s #2 -PrebarySinwaforPartl 2-3 May 2002

U JASMINE Analysis - Case 2

a It t Pg l-W 

I "

0'

O am 4 so 6 l o 10 o ItO T.tw__

J_:U Put I -1,..2dU.~

a o a . e D l< o Io

T. t Ml~

JAXIN Pwtl TM 2438t

a

, *0 0 01 01

o X t Ao4 co w to Xs

t~~~td*0

JMW0 I .TM. 2 d 2400

o

O tO£d trs ~ 4 r

a 

I

a a 0 0 10 to 1 1

#20

2 k a 2

2-3 Ihay 2002

Smoke layer temperaure sensitive to conduction heat loss me asm ut layer height less so)

rI Gaidtrsbur Bmacxw* Analk #2 -Pdlmboary Si uadoksp r Pan I

D-284 10
_ ~~~~~~~~~~~~~~~~~~~~~#21

JASMINE Analysis - Case 2

MAIfl: Put I.k PM MOft at .AIM~ Pwt I.Rw1*PaMu jIt Is

1'a -o~~~~~~~~~~ ~ otdU~tiDU

o- 14114 l14mIW .m__1. INW

JAXIMM PartIMM1.ptansatb JNM Pot IopW d Ufs

ao oA t DM. m 44014m to 00 14l14lJIM JIM 1 O

NS=,I Gheributr Dewhwa*Analyzl#2 BPreilmarysnSkdsibwjor arf1 2-3 May 2002

U #22

JASMINE Analysis - Case 3

~~tft I -Tfnt stab JASW Pt t l t120

IS . . . 16 4,t a 

o o

0 o 1 to gO 1 1 1 0 gO 14 14 14 114 lo4 114 1*4

TR.0-0SP

umZ Pa tI Tr" 21 af JSMW PW ITr*'. 214Mb

180 

-0-2W~

I 4 1 4 1141 1 1 

0 .? w MD wlb 0 

yttwX.

I

I

Is

14

14

0: 

-0-ao

a 20 4 a o wo.

Vt__" 

Smoke layer tempeabnre sensitive to conduction heat loss mechanism (ut layer hdght less so)

MJlsT, Gaisershu Beisdsmw* Anayis# 2 - etibma SONdomfor Part I 2-3 MaJy 2002

D-285 It
#23

JASMINE Analysis - Case 3

JAUM Pn . w1 oat J. h I -Tr ot

to- .0

Ia O

o ~ ~ ~ ~ ~~S D K W nn 0 4 0 8 O tt A I . . .

A J:: ota 1o 4A~ wl~pr

_ n a a 10 o S0 WW SW0 meIC 

Mesh rn aLso an impo sacnslaion

ANlSr Getrg Bewhmark n*Ss # 2 -Prdyu AmdolmJfr Par 1 2-3 May 2002

#24

* Closing Remarks

* Important general findings:

* conduction losses into walls/ceiling needs care

- sheet metal influences layer temp

* specification of restricted ventilation openings:

- has only small influence on layer temperature

- has a more important influence on layer height (mainly during later stages)

* Important findings for CFAST:

* choice of 'equivalent' ceiling height: - influences upper layer temperature

- but influences layer height only at early stages

* important findings for JASMINE:

* mesh resolution needs consideration

* sloping ceiling approximation ?

NS, Ga~zersbu BHvwhmw* Anabjs # 2 -Pemnwry Simaolmufor Part I 2-3 MJy 2002

D-286 12
#I

Benchmark Analysis # 2

Fire in a Large Hall

Proposalfor Part II

Stewart Miles

RM and &A ngindng CeBE RIM UK

TdTG.44 u&wk92 24924

Pa: .440192l6491

NlS4:CaGersur 8e*na*alwtr#2. wpralbOw 2-3 Ma2

#2

Objectives of Part II

* To extend scope of Part I to include:

* a realistic large volume nuclear power plant building - turbine hall

* larger fires - producing temperatures capable of greater danage

* 'target objects'

- cables

_ stmctural elements

* additional complexities:

- oxygen limitation effects

- multi-compartment (internal ceiling with openings)

Amp, Gauherzbwd Benai Analyl 2 -Pmposfor Pa II 2-3 May 2002

D-287

1
External Geometry and Vents

nudanicalrvea (Im x Im aqum)

II) 12

*$\ * * \ i To simplify task aswtme floor,

s \40 v walls and ceiling costmcted

from conre

80 o x e s s s S \\,, Doorwayseltherl x4mor

-it 4x4m ,"^,_k 

so

NIS: ct -fa 2- O20 3 

NhmE G,*hsighn &vxncan* Anadtl #2 -Proposal for Pan il 2-3 May 2002

Internal Geometry and Targets

-d

0C050smuindwe)_ (.0 

Mla) A4z bIM*eraibwoUrg

t~~~m0404~~~~s f ~~~~- A4 --- -- - -~ -~ ~ i

X11 r dai Apdlhi Yul I 1 Am SOUM,/M ti -- _:~~~~~~~~~~~~~~~~~~~~~j. t

30

N1 Galrhe 4m ayw mwAayar# -Pooslfr a i - ay20

D-288 2
#5

Internal Ceiling

*.u~9

tipma b

3 010 Model as two vertical copartr-ents with

one opening (vent) connecting them?

* - Qis \t

7- .

NlST: Gaw " B*ad : Andysw #2- Proposefor PanIpt 2-3 May 2wit 2

#6

Exercises

Oeee is cam,"a

1mx~mdooryopanft lmr~mdomway ot'eni~ge mhw~owypnn r4loey cpeanflge

no medmw" ofud vordatin lon d if medeej e"swt Venlilelon no medwleua vert etbn (divdd ehy bt'en tho O vmnt

mxo* reopenvVge d s c_ 1 Sftwtwo 

80 i' a' mecturdel tJJ 4g~lo ~on d the mInm l tIog penlion,

(dividd evi bteen the S ve r1e) _ *I ldlg tobn ho t lnbet

Heptane fuel (as in Part I)

S325 x 10'kg 4

\ 2 Am =0 Lit 0:t<S

Reporting procedure as for Part , plus:

oxygen level

target maximum incident flux, surface temp & centrline temp

I9Mhw= (and esmate of ehood of damage)

Af = 1.55 9~t<20minutes

NISZ G zftrsbum &nckhA* Andyhr # 2 -Propsafr Pan 2-3 May 2(W2

D-289 3
Detector Response

Modeling

Doug Beller

NFPA International

Purpose

* Background

* Proposal

D-291 1
Background

* SFPE Computer Model Evaluation

Task Group

* First model DETACT

* 3+ year effort

* Report issued soon

* Next model ASET

* (shouldn't take 3 years...)

DETACT evaluation

* ASTM E-1355: many tasks

* Verification of algorithm

* Sensitivity analysis

* "Blind" runs

* Attempted to compare algorithm to

original data

* New tests conducted

* Problems eventually worked out

D-292 2
DETACT

* Predicts activation time of fixedtemperature detectors

* Not for rate-of-rise

* Smoke detectors...

* Correlations for

* Ceiling jet temperature

* Ceiling jet velocity

DETACT Limitations

* Large, flat, smooth ceiling

* Unconfined, minimal layer formation

* Detector assumed to be exposed to max

C] velocity and temperature

* Implicit accounting of radiation and

conduction

D-293 3
Proposal

* Nuclear installations not

* Smooth

* Flat

m Open

* Does DETACT still apply?

* What happens when DETACT is used?

Proposal

* Is an evaluation of DETACT for

nuclear power plant applications a

good thing to do?

* Focus too narrow?

* Is it possible to develop a "post- prediction" correction factor to

account for nuclear configurations?

*"Implicit" accounting of non-ideal

configurations

D-294 4
Discussion

D-295

5
International Collaborative Project to Evaluate Fire Models

for Nuclear Power Plant Applications

Gaithersburg, MD, May 2-3,2002

A new model for time lag of

smoke detectors

0. KesWi-Rahkonen

VT Building and Transport

4'irContents

* Introduction

* Time lag theories and data

* Theory on filtration mechanisms

* Flow through the screen

* Soot flow through the screen

* Conclusions

SOA.IOC 2

D-297

1
Introduction

* Smoke detection links from the source to the

detector only partially modelled

* Smoke measurements difficult

* Large detection delays observed

* Smoke penetration Into the detector still a problem

OVAT

Time lag theories and data

* Heskestad 1977

At =y / V

ODAMW 4 

D-298 2
Experimental observations

Data:

Brozovsky 1991

;j 100 Cleary at al. 2000

Fits:

10 _Keski-Rahkonen 2001

1 At = l /( -7 F )

0 0.1 0.2 0.3 0.4 0.5 Confirming finite Velocity ~ ceiling jet velocity

DC2 5 _4q

Modelling of time lag

1000

I 10

Calculations:

Heskestad 1977 (1,2)

Keski-Rahkonen 2001 (4,5)

No newtonian fluid dynamic

theory able to explain finite

critical velocity

Li -Vowf

0 0.1 0.2 0.3

Velocity (m/e)

0.4 0.5

n

D-299 3
I. I

I I

New modelling ideas

* Simplified hemispherical detector body

* Insect screen separates inner from outer field

* Outer field from potential flow

* Screen penetration from diffusion battery models

* Air flow In the detector from the continuity equation

* Selective separation of smoke particles on the

screen

Simplified geometry

liy

r U8

0 U-

~(1) U8

(2)

f J

4qvr

4

D-300
Outer pressure field

1.0.

0.5 Curve fitting on experimental and

00 . QO xpotential fow

models around the

*1.0 stagnation point

*.5- ** *** *|**2t II** 0 | 1 6 *dit o 30 OD go 120 ISO 18

an ~ ~ ~ #n

IzVY

D-301

5
Smoke particle penetration

I

Ca

I

S

Cr

IL

0.1

0.01

0.001 v

1E-3 E-2 1E-1 1E+

Flow velocity through msh (m/a)

$*Ag= 11~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I

Conclusions

* Heskestad: At = y / v

* Experimental data show large time lag for slow ceiling jet

velocity

* Brozovsky: a finite critical ceiling jet velocity in variance

with Heskestad's theory

* Keski-Rahkonen: No newtonian fluid flow model able to

explain finite critical velocity

* This work:

* A new model proposed based on selective filtering of smoke

particles

* A closed calculation form derived for smoke penetration

N2A 12

D-302 6
iBMB Room Fire Test IBMB

I0

Foreseen German Real Scale

Cable Fire And Functional Failure

Tests

M. Roewekamp (GRS)

0. Riese, D. Hosser (BMB)

U

t 

U

ambient tenperature 400 

0C

E

M ~~~~~~U

0

Large scale test

Horizontal or

vertical cable tray

Pre-heating up to

400 OC

Local ignition

source (50 kW)

Typical results

* Time to ignition

* Flame spread

* Local temperatures

* Rate of heat release

* CO/CO

2 production

* Smoke production

local flame application 50 kW
0

4Is

Cable Tests Equipment IBMB

o iBMB test furnace

* Vertical

* Horizontal

o Smoke density measurement

o Function loss test equipment according

to DIN 4102-12

o Gas analysis equipment 02, CO, C02

^ Oxygen consumption method for the

determination of the heat release

Cable Fire Tests (horizontal) IBMB

36mI

I I

2
Horizontal / Vertical Cable Tray - IBMB

o Example of a horizontal cable tray

o Position of thermocouples

IA I C

0

door wall

3
a'I 0

Cable Fire And Functional Failure Tests iBMB

iBMB Proced. _

Heater and Gas burner: max 50 kW 1 opening 2.6 m

2

Material PVC PVC PVC PVC

Direction Horizontal Horizontal Vertical Vertical

Type of cables Power cables Signal cables Power cables Signal cables

Pre-heating I,

Functional test yes yes yes yes

I based on DIN 4102-12

Test furnace according to IBMB procedure

4
iBMB TU BRAUNSCHWG

Kerosene Fire Experiments

Dr. M. Roewekamp, GRS

Prof. Dr.-Ing. D. Hosser and Dr.-lng. R. Dobbernack,

iBMB of TU Braunschweig

5% Inlemational Collaborative Project meeting to Evaluate Fire

Models for NPP Applications,

Gaithersburg, MD, May, 2-3, 2002

Contents iBMB

* Goals and work program

* Available results from German research

* First results from literature

* First actual experimental results

* Summary and conclusions

Goals and Work Program iBMB

* Goals

* Estimation of basic data for simulating kerosene fires

under different boundary conditions

* Exemplary calculation of fire effects for selected

kerosene fire scenarios

* Rough estimate of the risk of explosion in case of

sprayed kerosene and the consequences

* Work program

* Kerosene pool fire experiments

* Comparison of the experimental results with data

from literature

* Definition of fire scenarios outside as well as inside

of buildings

* Fire simulations

* Rough estimate of the consequences of explosions

Results of German Research iBMB

* SR 144/1 experiments (1982-1985)

* Experiments with oil fire loads in pans of 2 m2 with

and without continuous feeding of oil and different

ventilation conditions

* Fire compartment temperatures 1080 - 1370 IC

* Burning rate 1,35-3,15 kg I min

* Energy release rate up to 2,2 MW / m2

* HDR fire experiments (1986-1992)

* Experiments with oil fire loads in pans of 1 -3 m2

with feeding of oil for different room geometries

* Fire compartment temperatures up to 1500 'C

* Burning rate up to 3,6 kg I m2-min

* Energy release rate up to 2,6 MW I m2

D-307
Results from Literature (1) iBMB

* Hydrocarbon fires

* Scaled offshore fire experiments

(SINTEF, Norway)

* Fast fire spreading on the pool surface

* Energy release rate 1,7 - 4,9 MW/m2

* Fluid fires in general

* In case of pool fires with sufficient oxygen,

medium "buming velocity'of approx. 3 mm/min

* Energy release rate of kerosene depending

on the heat release approx. 11,7 kWh 1 kg,

i.e. 1,4MW/rM2

lime-temperature Cu rves iBMB

._ _ 1: ISO curve

2: Hydrocarbon =- - curve HC

3: RABT curve

4: Rijkswaterstaat

curve RWS

. _- 5: EBA-curve

100 150 200

fire duration [min]

Results from Literature (2) iBMB

* Kerosene pool fire experiments

* Open kerosene pool fires (SANDIA, USA)

280 m2 pan, 15 cm water + 25 cm kerosene

* Fire spreading on the pool surface within 20 s

* Burning rate 4,1 - 4,9 kg / m2-min (effects of wind)

* Maximum temperatures 1300 -1500 C

* Heat flux density at a wall up to 4,5 m height

100 -130 kW / M2

* Kerosene explosion experiments

* Laboratory scale (Aeronautical Laboratories, USA)

* Flame point and explosion points uncertain

(composition of kerosene not well known)

Recent German Approach iBMB

* Kerosene pool fire experiments

* Kerosene experiments (February 2002) in steel pans of 0,5 M2

, 1,0 m2und o m

2

and kerosene level of 10 cm and 3 cm

* Measuring burning rate, temperature and radiation

heat in the fire compartment

* Definition of relevant fire scenarios

* Pool fires outside buildings

* Fires with combinations of kerosene and other fire

loads inside buildings; comparison with former

experiments

* Fire simulations

* Comparison of calculations with different types of

codes

D-308
Aviation Fuel Fire Experiments iBMB

Foreseen in Germany for 2002/03

* Kerosene pool fire experiments

* Inside confinements

* Outside buildings

* Combustible mixtures from fuel gas and air

inside confinements with the potential for

deflagration / detonation

* Fuel spray formation and fireball outside

buildings

Kerosene Pool Fires- BMB

Goals of the Experiments I

* Basic data for fire simulations

* Burning rate

* Energy release

* Flame temperature

* Heat flux density

* Consideration of dependencies

* Pool size

* Pool height

* Underground material (steel/concrete)

Kerosene Pool Fires Inside iBMB

Confinements

* Roomsize(LxWx H =3,6 m x 3,6 m x5,8 m)

* Pool size: 0,5 m2; 1,0 m2; 2,0 M2; 4,0 m2

* Pool height: 3 cm; 10 cm

* Ventilation

* Ventilation controlled

* Fire load controlled

* Effects of structures and equipment

* Concrete, steel, etc.

* Heat sinks (water tank)

* Cable trays in case of low fire loads

Measuring Equipment for

Kerosene Pool Fires

* Burning rate by mass loss rate

* Temperatures

* Plume

* 3 levels above the fire

* Inside and on structures and heat sinks

* On cable surface (fire inside compartment)

* Velocity

* Vie Plume height and wind velocity

. In the off-gas line (fire inside comparitrent)

* Heat flux at different locations

* Gas analysis (02, CO2 and CO)

* Heat camera

iBMB

D-309
Experimental Layout, iBMB

Measurements

* Fire compartment

* Length 3,6 m

* Width 3,6 m

* Height 5,7 m

* Measurements

* Plume temperature (6 locations)

* Three measurement levels (4 locations)

* Surface temperature (3 locations)

* Heat flux (4 locations)

* Mass loss

Fire Compartment Layout (1) iBMB

FTI 7 ~~T- -

_,

_.

_______

Kerosene Pool Fires Outside iBMB

Buildings

* Pool size: 0,5 m2; 1,0 in2

; 2,0 M2; 4,0 m2; 16 m2

* Filling level: 10 cm

* Ventilation

* No wind

* Effects of wind

* Reference equipment at a wall

* Concrete, steel, etc.

* Heat sinks (e.g. water storage tank)

D-310
Combustible Gas Air Mixtures iBMB

Inside Confinements

* Formation of combustible mixtures from

kerosene and air inside nearly closed

confinements

* Formation of gas clouds

* Spreading of gas and formation of mixtures

* Combustionlexplosion process

(deflagration, detonation, DDT)

Combustible Gas Air Mixtures iBMB

Inside Confinements

* Steps of the investigations:

* Comparison of data for kerosene and hydrogen

* Comparison of combustion process of kerosene

and hydrogen

* Specification of additional experiments (PTB)

* Status of the hydrogen modeling

* Applicability of available models for fuel gas

combustion/explosion (flame acceleration,

possibility of DDT)

* Exemplary analysis for model validation and

applicability

Aviation Fuel Spraying And iBMB

Fireball Outside Buildings

Questions:

* How far will the fuel been distributed after

the impact?

* What is the droplet size of the fuel droplets?

* Which amount of fuel is directly burnt in the

fireball, which amount is available for a pool

fire?

* What are the effects and consequences of

a fireball?

Fuel Spraying And Fireball iBMB

Outside Buildings

Investigation methods

* Fuel spraying =* impact experiments

* Depending on velocity, potential targets, amount,

etc.

* Droplet spectra, distribution

* Combustion w ignition experiments and modeling

* Amount of directly burnt droplets

* Fireball characteristics, potential for scale up

* Comparison with literature including reports on

aircraft crashes

X Model for fireball effects and amount of fuel left

D-311
Fuel Spraying And Fireball iBMB

Outside Buildings

Impact experiments with fluids (ITA Hannover)

* Experimental facility

* Acceleration of pressurized

air up to - oo s -/

* Video observation

* Variation at velocity,

fuel amount, target

* Droplet diagnosis _ -

* Total mass I surface

(gravitationaltoptical)

* Size distribution (mpactor)

* Veloity (PDA)

* First experiments foreseen for July 2002

Fuel Spraying and Fireball iBMB

Outside Buildings

Ignition Experiments (BAM/PTB) and

Fireball Modeling

* Ignition experiments

* Fuel spray ignition (droplet spectra

analogous to ITA-experiments)

* Fireball characteristics

* Amount of fuel for pool fire

* Numerical simulations

* Model validation with experiments

* Scaling up from small scale to real scale

experiments

Summary and Conclusions iBMB

* Goals of the activities

* Gaining important basic data with respect to

kerosene as used in Germany

* First rough estimates of the potential consequences of kerosene fires outside and inside of buildings

* Recent status

* Analysis of experimental data from German as well

as other institutions

* Kerosene pool fire experiments inside buildings)

* Continuation of work

* Definition and simulation of fire scenarios

* Identification of the significant parameters

* Expected results

* Statements with respect to the significance of

kerosene fires

* Assumptions for further investigations

D-312
Challenges in use of State-ofthe-Art Fire Modeling Tools

in Nuclear Power Plant

< S t Act Applications

B. Najafi, F. Joglar,

Science Applications International Corp.

R. Kassawara

EPRI Project Manager

* Introduction

* Fire modeling issues in nuclear power plants

- Areas where fire modeling can be applied

- Areas for future research

I: Slide: 2 . R I ll

D-313

I

1
* Prioritize fire modeling issues in nuclear power plants

* Identify areas where future research can reduce the

uncertainty associated with these fire modeling issues

Slide: 3 IrE=I2I

* Technical issues discussed in this presentation

are based on the capabilities of models

evaluated in EPRI's fire modeling project.

- MAGIC

- CFAST

- CompBrnllle

- FIVE

-!qA'=!-- Slide: 4 cc

D-314 2
* EPRI's Fire Modeling project provides guidance in using

fire models including hand calculations and selected zone

models

- FIVE

- COMPBRN-llle

- CFAST

- MAGIC

* Our conclusions are limited to lessons learned while

using the models.

* Some conclusions may apply to other models, including

computational fluid dynamics (CFD)

Slide: 5 el=2l

Either there is confidence in the modeling tools OR

estimates are adequate to support anticipated applications

1. Thermal effects of plumes, ceiling jets and radiation

2. General room heat up, and hot gas layer

3. Elevated fires and oxygen depletion

4. Multiple fires

5. Multi-compartments: corridors and multi-levels

6. Smoke migration, generation and density

7. Partial barriers and shields

8. Fire detection

Slide: 6 . ~~~~~~~~~~~~~~~~~~~C-1-r ll.

D-315 3
I

* This is typical of many scenarios in NPPs where

critical targets are located in close proximity of

fire source

* Fire conditions, including temperature and heat

flux in these areas can be estimated using hand

calculations

* Hand calculations and zone models can be use

to evaluate target response

Me Slide: 7 g It2I

* Larger, less congested plant areas

* These temperatures can be estimated with hand

calculations and zone models

* Zone models are recommended in cases where

natural and mechanical ventilation are part of the

scenario

Slide: 8 e-0=0

D-316

4
* Typical of cable tray fires

* Zone models can simulate oxygen depletion and

elevated fires

* The amount of oxygen available for combustion

is an indication of the capacity of the fire to burn

* Combustion in low oxygen environments is

subject of research

Or MESlide:9 MI=l2I

* Scenarios involving intervening combustibles,

such as transients and cables

* CFAST and MAGIC can simulate multiple fires

* Fires other that the pilot can be ignited based on

time, temperature and heat flux

* The effects of multiple plumes is captured

Slide: 10 MI=

D-317 5
* Common fire scenarios in auxiliary or turbine building

* Sometimes approximated with larger combined or smaller

separated enclosures

* Zone models can simulate fire conditions in multiple rooms

* CFAST and MAGIC have the capability of connecting

rooms with vertical and horizontal openings

* MAGIC provides an image of the geometry that is useful

when developing input files in multi-compartment scenarios

LAIC Slide: 11 0:1=

. -_ 1 I I   I I BP<;.  I I , :,,: ...11-111- -I ' - ,

* Fires in the main control room specially those resulting in

evacuation

* Smoke generation for the most part is plume entrainment

* Migration refers to the smoke movement between

compartments

* CFAST estimates products of combustion based on yields

4SU4C Slide: 12 Sl1121

D-318

6
* Used mostly as radiation shield to protect against

large fire source such as reactor coolant pump

* Magic can simulate radiation barriers (targets in

lower layer)

* Barriers have no thermal behavior

* Once targets are immersed in the smoke, they

are heated mostly by convection heat transfer.

Slide: 13 CIrfal

* Only a model for heat detection is available: DETACT

* Models for heat detection assumes well defined ceiling jets

* DETACT can be used for smoke detection - ?? - Smoke

detectors are designed to operate before well established

ceiling jets.

* Some hand calculations for smoke detection are also

available

SAIC Slide: 14 Em =2I

D-319

7
* Some of these issues are not amenable to analytical

solutions

1. Cable fires

2. Fire growth inside the main control board

3. Fire propagation between control panels

4. High energy fires

5. Fire suppression

6. Hydrogen or liquid spray fires

* Current EPRI methods rely on empirical models based

on a combination of operating experience and fire tests

SW ~ Slide: 15 Mll2l

* Important in NPP applications since cables are

major contributor to potential fire growth

* Fire propagation or flame spread throughout cable

trays can not be modeled.

* Currently EPRI methods use empirical models

based on cable fire tests

49 Slide: 16 ClI0l

D-320

8
* Such fires can be critical to safety

* The combustion process in low oxygen

environments is still subject of research

* Little empirical data to support the extent and timing

of fire spread

Slide: 17 I2I

* This is critical where source and target are both electrical

panels such as control room and electrical equipment

rooms

* These scenarios could be critical to safety

* Although zone models can simulate multiple fires based

on heat flux or ignition temperature, specification of

required parameters is usually uncertain.

* The problem of ignition of internal components in

electrical cabinets can not be addressed with current

models

* Current EPRI methods use empirical models based on

electrical cabinet fire tests.

Byru' Slide: 18 =I112I

D-321 9
* Such events are result of electrical faults in high voltage

switchgears and transformers (more of a concern when

indoors)

* The intensity and effects of explosions can not be predicted

with fire models

* Currently we use empirical evidence suggesting that

explosions can occur in high energy cabinets. Sustained

fires after the explosion have been observed. Thermal

effects of these fires can be assessed with existing fire

models

Ste Slide: 19 el=2I

* Automatic and manual suppression are one of the primary

feature (in addition to barriers) to mitigate consequences

of fire in NPPs

* Only CFAST can simulate water based fire suppression

with some restrictive assumptions

* Effects of gaseous suppression systems can not be

simulated with current models

* Effectiveness of suppression systems in deep-seeded fires

* EPRI methods relies on codes/standards to demonstrate

effectiveness

e Slide:20 I 2

D-322 10
I~~~~

~ ~~~~1 , ... 11 I-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Not very critical based of operating experience

* Fire models assume fires as a point source of

heat release. Effects of jet fires can not be

predicted

* Little empirical data to support a model

AR9r Slide: 21 UC Mar~l

* Issues that may not be amenable to analytical solutions

- Fire growth inside control room main control board

* CFD codes may have the capability, the scenario description is

questionable

- High energy fires

* Prediction of consequences of initial blast require different type of

models

- Hydrogen or liquid spray fires

* Areas for improvement in current codes

- Cable fires

- Fire suppression

- Panel to panel fire growth

Slide: 22 2f0I0l

YE o'}n~~~~~~~~~~~1 D-L iZ
* Areas of application

* Thermal effects of plumes, ceiling

jets and flame radiation

* Room heat up, and hot gas layer

* Elevated fires and oxygen

depletion

* Multiple fires

* Multi-compartments: corridors

and multi-levels

* Smoke generation and migration

* Partial barriers and shields

* Fire detection

* Areas for future research

* Cable fires

* Fire growth inside the main control

board

* Fire propagation between control

panels

* High energy fires

* Fire suppression

* Hydrogen or liquid spray fires

Slide: 23 evel

* Duke Power

* Exelon

* Public Service Electric & Gas

* Pacific Gas & Electric

* EDF

* NRC

Slide: 24

D-324

12
Proposal for Full-Scale Tests and

Blind Validation Exercises

Moni Dey, U.S. NRC

Outline

* Background and need for validation

* Proposed 3-year plan

* Solicitation of participation

* Proposed schedule for t full-scale test

and blind validation exercise

proposal for Full-Scale Tests and

3tandard Problem Exercises D-325 1
Conclusions of

Benchmark Exercise # 1

* Trends predicted by models are reasonable, and

provide useful information

• Similar results from most codes, including zone

and CFD

* International blind validation exercise, with

emphasis on quantifying uncertainties, will add

confidence to findings

* Flux incident on and thermal response of target

were key issues in exercise

Review of Validation Database

* UK IMC validation database report

* Specific validation of fire models in

benchmark exercise

* Improvement in quantification of

uncertainty needed

* Thermal response of target may benefit

from additional validation

Proposal for Full-Scale Tests and

Standard Problem Exercises D-326 2
Plan for NRC Fire Model

Research Program

Near Term Needs

* Conduct tests for international blind

validation exercises to extend confidence in

current models

Long Term Needs

* Conduct research to improve fire modeling

capability, and validate improved methods

Proposed Test Program

FY02 FY03 FY04

Test Series Cable tray Multi com- Control

fires partment room fires

fires (tentative)

Objective Confirm Examine Examine

present flow issues smoke

findings _ issues

Proposal for Full-Scale Tests and

Standard Problem Exercises 3

D-327
Cable Tray Fire Test Series

* Objective:

* Investigate issues identified in benchmark

exercise

* Establish measurement uncertainties

* Quantify uncertainties in prediction of cable

temperatures for range of scenarios

Proposal for Full-Scale Tests and

Standard Problem Exercises 4

D-328
Specific Investigation of

Effects of Key Variables

* Fire intensity

* Distance between fire source and cable

* Cable diameter and composition

* Elevation of cable

* Bundling of cables in a tray

* Smoke concentration

Solicitation of Participation

* NRC invites participation in international

blind validation exercises with respective

fire models

* Mutual benefit gained through exercise of

different models

* Invite engagement in experimental

program and data analyses

3roposal for Full-Scale Tests and

3tandard Problem Exercises 5

D-329
Schedule for Ist Full-Scale

Test and Exercise

* Develop detailed test specification - August 30,

2002

* Discuss proposed test specification - October,

02 (6th meeting at BRE)

* Finalize test specification - December, 2002

* Submit fire model predictions for defined

problem - March, 2003

• Conduct tests - March 2003

Proposal for Full-Scale Tests and

Standard Problem Exercises D-330 6
C FORM 335 U.S. NUCLEAR REGULATORY COMMISSION 1. REPORT NUMBER

s) (Assigned by NRC, Add Vol., Supp., Rev.,

1,M BIBLIOGRAPHIC DATA SHEET and Addendum Numbers, it any.)

1,3202 BBIGAHCDT HE

(See nstruclions on the reverse)

rITLE AND SUBTITLE NUREGJCP.0181

International Collaborative Project to

Evaluate Fire Models for Nuclear Power Plant Applications: Proceedings of 5th Meeting 3. DATE REPORT PUBLISHED

MONTH YEAR

October 2003

4. FIN OR GRANT NUMBER

NiA

AUTHOR(S) 6. TYPE OF REPORT

M. Dey (NRC), A. Hamins (NIST), S. Miles (BRE) Technical

7. PERIOD COVERED (clusive Dates)

N/A

PERFORMING ORGANIZATION -NAME AND ADDRESS (If NRC. provide Division, Officea or Region. U.S. Nuclear Regulatory Commisson, and mailing address;if contractor,

provide name and mailing address.)

Division of Risk Analysis and Applications Building and Fire Research Laboratory Fire and Risk Sciences Division

Office of Nuclear Regulatory Research National Institute of Standards & Technology Building Research Establishment

U.S. Nuclear Regulatory Commission Gaithersburg, MD 20899, USA Garston, Watford WD25 9XX, UK

Washington, D.C. 20555-0001, USA

SPONSORING ORGANIZATION - NAME AND ADDRESS (IfNRC, type 'Same as above'; if contractor, provide NRC Division, Office or Region, US. Nuclear Regulatory Commission,

and mailing address.)

Same as above

). SUPPLEMENTARY NOTES

See NUREG/CP-0170 and NUREG/CP-0173 for summaries of 1st and 2nd meetings.

I. ABSTRACT (200 words or less)

The 5th Meeting of the International Collaborative Project to Evaluate Fire Models for Nuclear Power Plant Applications was

hosted by the National Institute of Standards and Technology (NIST), U.S. Department of Commerce and held at NIST

headquarters at Gaithersburg, Maryland on May 2 and 3, 2002. Thirty three participants from five countries attended the

international meeting. The purpose of the 5th meeting was mainly to discuss the results of Benchmark Exercise # 2, Pool

Fires in Large Halls,* conducted in the project. Validation and regulatory applications of fire models were also presented and

discussed in the meeting. The results presented for Part I of Benchmark Exercise # 2 were generally quite encouraging. While

the general, qualitative, nature of the experiments had been captured in the simulations, a number of issues had arisen.

Furthermore, the parametric analysis undertaken by a number of participants had yielded useful information. Different

conclusions have been drawn on the most significant, or controlling, parameters. The combined effect of the choice of heat of

combustion, combustion efficiency and radiative traction was found to be an important factor. The validation and application of

several, diverse fire models, ranging from empirical equations organized in worksheets to zone, lumped-parameter, and

computational fluid dynamic (CFD) models, were presented and discussed at the meeting. The discussions emphasized the

need to validate and determine the accuracy of such models, especially to understand the differences in the predictive capabilities and margins of uncertainty for the different types of models over a range of fire scenarios. This information is

needed to establish safety factors and implement effective applications of these models in a regulatory framework. The need

to define credible fire scenarios and generate data for fire sources, especially cable tray fires, was emphasized.

2. KEY WORDS/DESCRIPTORS (List words orphrases that will assist researchers hi locating the report.) 13. AVAILABILITY STATEMENT

Fire Models unlimited

Fire Risk and Hazard Analysis 14. SECURITY CLASSIFICATION

Performance-Based Methods (This Page)

Nuclear Power Plants unclassified

Collaborative Project (This Report)

unclassified

15. NUMBER OF PAGES

16. PRICE

RC FORM 335 (2-89) This lormn was electronically poduced by Elte Federal Forris, Inc.
Printedi

son recycled 

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