WORST-CASE CONSEQUENCE ANALYSIS HYDROGEN AND GASOLINE FUELING STATION IN BERKLEY, CALIFORNIA

Transcription

1 WORST-CASE CONSEQUENCE ANALYSIS HYDROGEN AND GASOLINE FUELING STATION IN BERKLEY, CALIFORNIA Prepared For Fiedler Group 299 N. Euclid Avenue, Suite 550 Pasadena, CA Prepared By Quest Consultants Inc th Avenue N.W. Norman, OK Telephone: Fax: CAS01-RevD0

2 7094-CAS01-RevD0 Page i WORST-CASE CONSEQUENCE ANALYSIS HYDROGEN AND GASOLINE FUELING STATION IN BERKLEY, CALIFORNIA Table of Contents 1.0 INTRODUCTION OVERVIEW OF PROPOSED AUTOMOTIVE FUELING STATION Facility Location Meteorological Data Description of the Proposed Siting Requirements for the Hydrogen Automotive Fuel System in the Existing Gasoline Automotive Fueling Station POTENTIAL HAZARDS Hazards Identification Introduction to Physiological Effects of Fires and Explosions Selection of Accidental Release Case Studies Overview of Methodology Development of Hazard Scenarios Initial Screening via Hazard Zone Analysis Final Selection of Hazard Cases WORST-CASE CONSEQUENCE MODELING RESULTS Releases Resulting in the Largest Downwind Hazard Zones Description of Potential Hazard Zones Flash Fires Fire Radiation Vapor Cloud Explosions Summary of Maximum Hazard Zones CONCLUSIONS REFERENCES Page

3 7094-CAS01-RevD0 Page 1 WORST-CASE CONSEQUENCE ANALYSIS HYDROGEN AND GASOLINE FUELING STATION IN BERKLEY, CALIFORNIA 1.0 INTRODUCTION Quest Consultants Inc. was retained by the Fiedler Group to perform a worst-case consequence analysis on the proposed hydrogen fueling equipment additions to an existing gasoline fueling station. The proposed project will involve adding hydrogen unloading, storage vessels, compressors, transfer, and dispenser equipment to an existing gasoline fueling station. The worst-case analysis was designed to satisfy the hazards analysis requirements under the California Environmental Quality Act. The study was divided into three tasks. Task 1. Determine the maximum credible potential releases, and their consequences, for existing gasoline automotive fueling operations. Task 2. Determine the maximum credible potential releases and their consequences for proposed hydrogen automotive fueling equipment. Task 3. Determine whether the consequences associated with the proposed additions generate a potential hazard that is larger than the potential hazard which currently exists in the station. Potential hazards from the existing and new equipment are associated with accidental releases of flammable gas (hydrogen) or flammable liquids (gasoline). Hazardous events associated with gas releases include jet fires, flash fires, and vapor cloud explosions. Hazardous events associated with flammable liquids include pool fires, flash fires, and vapor cloud explosions. The hazard of interest for flash fires is direct exposure to the flames. Flash fire hazard zones are determined by calculating the maximum size of the flammable gas cloud prior to ignition. These hazard zones are defined by the lower flammable limit (LFL) of the released hydrocarbon mixture. For vapor cloud explosions, the hazard of interest is the overpressure created by the blast wave. The hazard of interest for jet and pool fires is fire radiation. For each type of hazard identified (radiant, overpressure), maximum distances to potentially injurious levels are determined. The hazard levels are based on events that could cause an injury to persons in the area.

4 7094-CAS01-RevD0 Page OVERVIEW OF PROPOSED AUTOMOTIVE FUELING STATION 2.1 Facility Location The proposed location for the addition of the hydrogen automotive fueling equipment is an existing gasoline automotive fueling station located in Berkley, California. The station is bounded by Bonar Street to the west and University Avenue to the north. Layout of the station and major roads bounding the facility are presented in Figures 2-1 and Meteorological Data Meteorological data for the Berkley area were reviewed to determine representative values for temperature and relative humidity. Wind speed and stability class were also reviewed to determine the range of conditions that are possible at the site. In this study, a low wind/stable condition 1 m/s (2.2 mph) wind, F stability was evaluated for each dispersion calculation. These conditions often approximate the worst-case weather conditions for dispersion analysis. For the purposes of this analysis, the vapor cloud was assumed to travel in any direction with equal probability. When performing pool fire and jet fire calculations, a high wind that bends the flame is considered a worst-case condition. In this study, all fire radiation calculations were performed using 5 m/s (11.2 mph) winds. 2.3 Description of the Proposed Siting Requirements for the Hydrogen Automotive Fuel System in the Existing Gasoline Automotive Fueling Station The automotive hydrogen system design is in conformance with the National Fire Protection Association (NFPA) 2 Hydrogen Technologies Code [2016], as it will be the adopted code for the local jurisdictional fire department. One of the requirements of NFPA 2 is that radiant impacts greater than 1,500 Btu/hr ft 2 are not allowed offsite. The design of the hydrogen fueling system in the existing Berkley gas station satisfies this requirement, often due to the addition of mitigation in the form of solid barrier walls. The locations of the hydrogen and gasoline unloading equipment and fuel dispensers, as well as barrier walls, are presented in Figure 2-1.

5 7094-CAS01-RevD0 Page 3 Figure 2-1 Location of Automotive Fueling Equipment in the Existing Gasoline Fueling Site

6 7094-CAS01-RevD0 Page 4 Figure 2-2 Aerial View of Automotive Hydrogen/Gasoline Fueling Site

7 7094-CAS01-RevD0 Page POTENTIAL HAZARDS 3.1 Hazards Identification The potential hazards associated with the existing gasoline automotive fueling station and those associated with the proposed addition to the existing station involving hydrogen fuel for automobiles are a function of the materials being handled, transportation systems, procedures used for operating and maintaining the facility, and hazard detection and mitigation systems. The hazards that are likely to exist are identified by the physical and chemical properties of the materials being handled and the process conditions. For hydrocarbon fuel facilities, the common hazards are: flash fires (gas or liquid releases) jet fires (gas releases) pool fires (liquid releases) vapor cloud explosions (gas or liquid releases) The automotive facility under evaluation was divided into two types of areas. The hazards expected to be identified are listed in Table 3-1. Table 3-1 Summary of Hazards Areas Automotive Hydrogen Equipment Automotive Gasoline Equipment Type of Hazards Found in Area Breach of vapor line or vessel resulting in: Jet fire Flash fire Vapor cloud explosion Breach of liquid line or vessel resulting in: Pool fire Flash fire Vapor cloud explosion 3.2 Introduction to Physiological Effects of Fires and Explosions The analysis performed on the automotive gasoline station modifications involved the evaluation of potential hazardous material releases. The potential releases may result in one or more of the following hazards: Exposure to fire radiation Pool fire (spill onto concrete substrate) Jet fire (rupture of line followed by ignition) Flash fires (ignition of flammable vapors) Exposure to explosion overpressure Vapor cloud explosion (dispersion & explosion of a flammable vapor cloud following release) In order to compare the hazards associated with each type of hazard listed above, a common measure of consequence or damage must be defined. In consequence and risk analysis studies, a common measure for such hazards is their impact on humans. For each of the fire and explosion hazards listed, there are data available that define the effect of the hazard on humans.

8 7094-CAS01-RevD0 Page 6 When comparing a flammable hazard to an explosive hazard, the magnitude of the hazard s impact on humans must be identically defined. For instance, it would not be meaningful to compare human exposure to nonlethal overpressures (low overpressures which break windows) to human exposure to lethal fire radiation (34,500 Btu/hr ft 2 for five seconds). Thus, in order to compare the hazards of fires and explosions on humans, equivalent levels of hazard must be defined. The endpoint hazard criterion defined in this study corresponds to a hazard level which might cause an injury. With this definition, the injury level must be defined for each type of hazard (radiant heat or overpressure exposure). Table 3-2 presents endpoint hazard criteria approved by the Air Quality Management District (AQMD) for previous studies of this type. Hazard Type Flash fires (flammable vapor clouds) Table 3-2 Consequence Analysis Hazard Levels (Endpoint Criteria for Consequence Analysis) Injury Threshold Exposure Duration Hazard Level Reference Instantaneous LFL 40 CFR 68 [EPA, 1996] Radiant heat exposure 40 sec 1,600 Btu/hr ft 2 * 40 CFR 68 [EPA, 1996] Explosion overpressure Instantaneous 1.0 psig** 40 CFR 68 [EPA, 1996] 40 CFR 68. United States Environmental Protection Agency RMP endpoints. * Corresponds to second-degree skin burns. ** Corresponds to partial demolition of houses. 3.3 Selection of Accidental Release Case Studies Overview of Methodology The purpose of the hazard case selection methodology is to define the maximum credible hazard scenario for fuel equipment type that might result in an impact to the public. The methodology is developed in three major steps: Development of hazard scenarios o Initial review o Detailed review of process flow diagrams o Review of process conditions o Review of available safety studies Screening of hazard scenarios via hazards analysis Final selection of hazard cases Development of Hazard Scenarios The analysis begins with a general review of the gasoline and hydrogen fuel handling processes. Any written description of the new or modified processes is studied to determine the physical and chemical transformations occurring and the general flow of material. After the process features are known, process flow diagrams (PFDs) are reviewed and compared to the written descriptions.

9 7094-CAS01-RevD0 Page 7 The detailed review of the PFDs begins by tracing the major process flow lines. When the major flows within are found, the material balances or process condition information are reviewed for each major line to determine the exact nature of the material within the line or vessel. Each of the major flow lines is taken individually and evaluated to determine the potential for producing a major hazard if a leak or rupture occurred. At this point in the analysis, a list of potential areas of concern is started; this list is continually refined and added to during the remaining analysis steps. Several factors are involved in the initial selection of hazard areas: Flammability of the material Line size Normal flow rate in the line Severity of the process conditions The factors described above are not weighted equally in the evaluation. The flammability and process conditions are given more weight than the other factors. Any available safety studies (primarily process hazards analysis studies such as a HAZOP) are reviewed to ensure that all potential hazard areas are identified and the list of potential release scenarios is complete Initial Screening via Hazard Zone Analysis The hazard zones resulting from the worst-case releases of similar hazard scenarios are evaluated to determine the process areas that could release material with a potential for public impact. When performing site-specific consequence analysis studies, the ability to accurately model the release, dilution, and dispersion of gases and aerosols is important if an accurate assessment of potential exposure is to be attained. For this reason, Quest uses a modeling package, CANARY by Quest, that contains a set of complex models that calculate release conditions, initial dilution of the vapor (dependent upon the release characteristics), and the subsequent dispersion of the vapor introduced into the atmosphere. The models contain algorithms that account for thermodynamics, mixture behavior, transient release rates, gas cloud density relative to air, initial velocity of the released gas, and heat transfer effects from the surrounding atmosphere and the substrate. The release and dispersion models contained in the QuestFOCUS package (the predecessor to CANARY by Quest) were reviewed in a United States Environmental Protection Agency (EPA) sponsored study [TRC, 1991] and an American Petroleum Institute (API) study [Hanna, Strimaitis, and Chang, 1991]. In both studies, the QuestFOCUS software was evaluated on technical merit (appropriateness of models for specific applications) and on model predictions for specific releases. One conclusion drawn by both studies was that the dispersion software tended to overpredict the extent of the gas cloud travel, thus resulting in too large a cloud when compared to the test data (i.e., a conservative approach). A study prepared for the Minerals Management Service [Chang, et al., 1998] reviewed models for use in modeling routine and accidental releases of flammable and toxic gases. CANARY by Quest received the highest possible ranking in the science and credibility areas. In addition, the report recommends CANARY by Quest for use when evaluating toxic and flammable gas releases. The specific models (e.g., SLAB) contained in the CANARY by Quest software package have also been extensively reviewed.

10 7094-CAS01-RevD0 Page 8 For vapor cloud explosion (VCE) calculations, Quest uses QMEFS, which is a variation of the Baker- Strehlow-Tang (BST) method. QMEFS [Marx & Ishii, 2017] is based on experimental data involving vapor cloud explosions, and is related to the amount of confinement and/or obstruction present in the volume occupied by the vapor cloud. Quest s QMEFS model is based on the premise that the strength of the blast wave generated by a VCE is dependent on the reactivity of the flammable gas involved, the presence (or absence) of structures such as walls or ceilings that partially confine the vapor cloud, the spatial density of obstructions within the flammable cloud [Baker, et al., 1994, 1998], the average size of those obstacles, and the overall size of the confined or congested space. This model reflects the results of several international research programs on vapor cloud explosions, which show that the strength of the blast wave generated by a VCE increases as the degree of confinement and/or obstruction of the cloud increases. The following quotations illustrate this point. On the evidence of the trials performed at Maplin Sands, the deflagration [explosion] of truly unconfined flat clouds of natural gas or propane does not constitute a blast hazard. [Hirst and Eyre, 1982] (Tests conducted by Shell Research Ltd., in the United Kingdom.) Both in two- and three-dimensional geometries, a continuous accelerating flame was observed in the presence of repeated obstacles. A positive feedback mechanism between the flame front and a disturbed flow field generated by the flame is responsible for this. The disturbances in the flow field mainly concern flow velocity gradients. Without repeated obstacles, the flame front velocities reached are low both in two-dimensional and three-dimensional geometry. [van Wingerden and Zeeuwen, 1983] (Tests conducted by TNO in the Netherlands.) The current understanding of vapor cloud explosions involving natural gas is that combustion only of that part of the cloud which engulfs a severely congested region, formed by repeated obstacles, will contribute to the generation of pressure. [Johnson, Sutton, and Wickens, 1991] (Tests conducted by British Gas in the United Kingdom.) Researchers who have studied case histories of accidental vapor cloud explosions have reached similar conclusions. It is a necessary condition that obstacles or other forms of semi-confinement are present within the explosive region at the moment of ignition in order to generate an explosion. [Wiekema, 1984] A common feature of vapor cloud explosions is that they have all involved ignition of vapor clouds, at least part of which have engulfed regions of repeated obstacles. [Harris and Wickens, 1989] The strength of the blast wave predicted by the QMEFS VCE model is directly related to the size of the obstructed or partially confined volume that is filled with a flammable mixture of gas and air, and five additional parameters. Fuel Reactivity: A fuel s reactivity is characterized by its laminar burning velocity (LBV). Because the QMEFS model is based on the BST model, certain LBVs match the BST categories of high, medium, and low. For example, ethylene, with an LBV of approximately 75 cm/s, was explicitly

11 7094-CAS01-RevD0 Page 9 defined as a high reactivity fuel in the BST test series that defined that model. Most other fuels (propane, natural gas) have an LBV around 43 cm/s, making them medium reactivity fuels. Volume Blockage Ratio (VBR): The density of obstacles within the flammable cloud influences the peak overpressure due to the generation of turbulence along the flame front. VBR is defined as the fraction of a particular volume that is occupied by obstacles. Number of Confining Planes: The number of confining planes affects the strength of an explosion, potentially limiting the expansion of the flame front. The number of planes can be any number from 0 to 6, but is typically limited to values of 1 ( 3-D flame expansion with ground reflection), 2 ( 2-D expansion, or what occurs between flat, parallel surfaces), or 1.5 ( 2½-D, for situations that begin as 2-D and quickly transition to 3-D, or have one confining plane that is semi-porous or frangible). Flame Run-up Distance: This dimension is a descriptor for the maximum distance which a flame front can travel within the burning cloud. This value is typically limited to the longest horizontal dimension of the congested area. Average Obstacle Diameter: As the size of obstacles decreases, the turbulence generated in a burning cloud increases, which increases the peak overpressure that is produced. The default value, from the BST test series, is 2 inches ( m). CANARY also contains models for pool fire and jet fire radiation. These models account for impoundment configuration, material composition, target height relative to the flame, target distance from the flame, atmospheric attenuation (includes humidity), wind speed, and atmospheric temperature. Both models are based on information in the public domain (published literature) and have been validated with experimental data. More information on CANARY is available upon request Final Selection of Hazard Cases Using the data collected for potential hazardous releases and the initial screening hazard zone calculations, a final selection of hazard cases is made. These selections generally define the maximum extent of any credible potential hazard that could occur in the process area being evaluated.

12 7094-CAS01-RevD0 Page WORST-CASE CONSEQUENCE MODELING RESULTS The results of the worst-case consequence modeling calculations for the existing and modified automotive fueling station are presented in this section. In addition, several hazard zones are overlaid onto the facility map in order to demonstrate the possible public exposure to the defined hazard levels. 4.1 Releases Resulting in the Largest Downwind Hazard Zones With the completion of the hazard identification and consequence modeling calculations described in Section 3 for both the existing and proposed automotive fueling station configurations, the release which generates the largest hazard zone can be identified. These releases are listed in Table 4-1. Table 4-1 Potential Accidents Resulting in Maximum Potential Hazard Operation Automotive Gasoline Automotive Hydrogen Status of Potential Hazard (E) Existing, (N) New E N Potential Release (Hazard) Rupture of liquid unloading line from gasoline tank truck (pool fire) Rupture of hydrogen unloading line leaving hydrogen tube trailer (jet fire) 4.2 Description of Potential Hazard Zones Flash Fires A release of flammable fluid, if not ignited immediately, will create a vapor cloud that travels downwind and disperses. The extent of the flammable zone is defined by the lower flammable limit (LFL). If the flammable cloud is ignited after reaching its full extent, the largest possible flash fire will result. This hazard extends approximately 30 ft downwind from the point of release for the existing gasoline automotive fuel station as well as the new hydrogen system. The flash fire hazard zone has a vulnerability zone (a circle centered at the point of release whose radius is equal to the maximum hazard distance) that covers a much larger area than the actual vapor cloud Fire Radiation The most significant fire radiation hazards that might occur are pool fires from gasoline tank truck unloading releases and jet fires from a hydrogen release. Unlike the dispersion calculations, the worstcase atmospheric conditions for fire radiation calculations occur when the winds are high, allowing the flame to bend downwind. The largest vulnerability zones for the automotive gasoline and hydrogen releases are presented in Figure Vapor Cloud Explosions One of the possible results of a flammable liquid or gas release is the ignition of flammable vapors, which could result in a VCE. An example of an event tree showing the sequence of events that could lead to a VCE is presented in Figure 4-2. The 1.0 psi vapor cloud explosion overpressure hazard footprint following a rupture of the hydrogen unloading line from the tube trailer extends 11 feet from the hydrogen unloading area where flammable vapors originate. Gasoline vapors are not capable of producing a 1.0 psi overpressure when ignited in open areas (such as this fueling station) due to their lower reactivity as compared to hydrogen.

13 7094-CAS01-RevD0 Page 11 Figure 4-1 Maximum Vulnerability Zones for Worst-Case Gasoline and Hydrogen Releases

14 7094-CAS01-RevD0 Page 12 Release Size Ignition Timing Outcome Immediate Pool Fire, Jet Fire Rupture Delayed Flash Fire, VCE, Pool fire, Jet Fire None Dissipation Immediate Pool Fire, Jet Fire Release of Flammable Fluid Major Leak Delayed Flash Fire, VCE, Pool fire, Jet Fire None Dissipation Immediate Pool Fire, Jet Fire Minor Leak Delayed Flash Fire, VCE, Pool fire, Jet Fire None Dissipation Figure 4-2 Event Tree for a Flammable Gas Release 4.3 Summary of Maximum Hazard Zones Table 4-2 presents a listing of the type and size of the largest potential hazards which dominate the gasoline and hydrogen automotive fuel operations. Note that for each automotive fuel, the status is defined as E or N (existing or new). Table 4-2 Maximum Hazard Distances for Maximum Credible Event for Each Automotive Fuel Gasoline Hydrogen Automotive Fuel Release Release from unloading line from the gasoline tank truck Release from unloading line on hydrogen tube trailer Status of Potential Hazard (E) Existing (N) New Maximum Distance (ft) from Release Point to Flash Fire (LFL) Explosion Overpressure (1.0 psi) Pool/Jet Fire Thermal Radiation (1,600 Btu/hr ft 2 ) E N Overall, the proposed addition of automotive hydrogen to the existing automotive gasoline station results in no increases in the size of potential hazards. Another way to say this is that the potential impacts due to hydrogen releases are smaller than the potential impacts of gasoline releases that currently exist in the fueling station.

15 7094-CAS01-RevD0 Page CONCLUSIONS Quest Consultants Inc. was retained by the Fiedler Group to perform a worst-case consequence analysis on the existing automotive gasoline operation and the proposed automotive hydrogen operation at an existing station in Berkley, California. The worst-case analysis was designed to satisfy the hazards analysis requirements under the California Environmental Quality Act. The following three tasks were completed as part of the study. Task 1. Determine the maximum credible potential releases, and their consequences, for existing automotive fuel (gasoline). Task 2. Determine the maximum credible potential releases and their consequences for the proposed hydrogen automotive fuel operations. Task 3. Determine whether the consequences associated with the proposed hydrogen fueling generate a potential hazard that is larger than the potential hazard which currently exists in the station. The primary conclusion that can be drawn from the completion of these tasks is that the proposed modifications to the existing station do not result in larger potential hazard zones than those posed by the existing automotive gasoline station configuration. This result is primarily due to the nature of the hydrogen fueling equipment additions, and the compliance with NFPA 2, including barrier walls to limit the potential offsite impacts. With the maximum hazard zones defined for each fuel type, the fuels can be divided into three categories, dependent on their potential to impact the public. The categories are defined as: Units with no potential pre- or post-project off-site impacts (hazard zones are contained on-site). Units with potential pre- or post-project off-site impacts, but post-project impacts are no larger than pre-project (existing) impacts. Units with potential off-site impacts. Post-project impacts are larger than pre-project impacts. HYDROGEN FUELING OPERATIONS GASOLINE FUELING OPERATIONS NONE One specific conclusion can be drawn from a review of the worst-case consequence modeling results: The existing automotive gasoline station has the ability to create a hazard that could extend slightly off the property. It should be kept in mind that for the worst-case scenarios evaluated in this study to occur, the following conditions must be met. (1) A full rupture of the line occurs. (2) The release ignites within minutes of the rupture. (3) The wind speed is low (less than 3 mph) for flash fire or high (larger than 10 mph) for pool or jet fires. This sequence of events is highly unlikely and only results in an off-site hazard (flammable vapor dispersion or radiant impacts) for a limited number of potential releases.

16 7094-CAS01-RevD0 Page REFERENCES Baker, Q. A., M. J. Tang, E. Scheier, and G. J. Silva (1994), Vapor Cloud Explosion Analysis. 28 th Loss Prevention Symposium, American Institute of Chemical Engineers (AIChE), April 17-21, Baker, Q. A., C. M. Doolittle, G. A. Fitzgerald, and M. J. Tang (1998), Recent Developments in the Baker- Strehlow VCE Analysis Methodology. Process Safety Progress, Vol. 17, No. 4, Winter, 1998, pp Chang, Joseph C., Mark E. Fernau, Joseph S. Scire, and David G. Strimatis (1998), A Critical Review of Four Types of Air Quality Models Pertinent to MMS Regulatory and Environmental Assessment Missions. Mineral Management Service, Gulf of Mexico OCS Region, U.S. Department of the Interior, New Orleans, November, EPA (1996), Accidental Release Prevention Requirements: Risk Management Programs Under the Clean Air Act, Section 112(r)(7). Environmental Protection Agency, 40 CFR Part 68, Hanna, S. R., D. G. Strimaitis, and J. C. Chang (1991), Hazard Response Modeling Uncertainty (A Quantitative Method), Volume II, Evaluation of Commonly-Used Hazardous Gas Dispersion Models. Study cosponsored by the Air Force Engineering and Services Center, Tyndall Air Force Base, Florida, and the American Petroleum Institute; performed by Sigma Research Corporation, Westford, Massachusetts, September, Harris, R. J., and M. J, Wickens (1989), Understanding Vapour Cloud Explosions An Experimental Study. The Institution of Gas Engineers, Communication No. 1408, Hirst, W. J. S., and J. A. Eyre (1982), Maplin Sands Experiments 1980: Combustion of Large LNG and Refrigerated Liquid Propane Spills on the Sea. Proceedings of the Second Symposium on Heavy Gases and Risk Assessment, Frankfurt am Main, May 25-26, 1982: pp Johnson, D. M., P. Sutton, and M. J. Wickens (1991), Scaled Experiments to Study Vapour Cloud Explosions. IChemE Symposium Series No. 124, Hazards XI, New Directions in Process Safety, Manchester, United Kingdom, April, 1991: pp Marx, J.D. and B.R. Ishii (2017), Revisions to the QMEFS Vapor Cloud Explosion Model AIChE Spring Meeting & 13 th Global Congress on Process Safety, San Antonio, TX, March 26-29, NFPA 2 (2016), Hydrogen Technologies Code. National Fire Protection Association, Quincy, Massachusetts, ISBN (Print) ISBN (PDF) TRC (1991), Evaluation of Dense Gas Simulation Models. Prepared for the U.S. Environmental Protection Agency by TRC Environmental Consultants, Inc., East Hartford, Connecticut 06108, EPA Contract No , May, van Wingerden, C. J. M., and J. P. Zeeuwen (1983), Flame Propagation in the Presence of Repeated Obstacles: Influence of Gas Reactivity and Degree of Confinement. Journal of Hazardous Materials, Vol. 8, 1983: pp Wiekema, B. J. (1984), Vapour Cloud Explosions An Analysis Based on Accident (Part I). Journal of Hazardous Materials, Vol. 8, 1984: pp

17 7094-CAS01-RevD0 Page 15 Wiekema, B. J. (1984), Vapour Cloud Explosions An Analysis Based on Accident (Part II). Journal of Hazardous Materials, Vol. 8, 1984: pp